Science.gov

Sample records for study fragmentation reactions

  1. Studies of complex fragment emission in heavy ion reactions

    SciTech Connect

    Charity, R.J.; Sobotka, L.G.

    1992-01-01

    Our work involves the study of intermediate energy heavy-ion nuclear reactions. This work has two foci. On the one hand, we desire to learn about the properties of nuclear matter under abnormal conditions, in this energy domain, predominately low densities. This purpose runs abreast of the second, which is the study of the relevant reaction mechanisms. The two objectives are inexorably linked because our experimental laboratory for studying nuclear matter properties is a dynamic one. We are forced to ask how nuclear matter properties, such as phase transitions, are reflected in the dynamics of the reactions. It may be that irrefutable information about nuclear matter will not be extracted from the reaction work. Nevertheless, we are compelled to undertake this effort not only because it is the only game in town and as yet we do not know that information cannot be extracted, but also because of our second objective. The process leads to an understanding of the reaction mechanism themselves and therefore to the response characteristics of finite, perhaps non-equilibrium, strongly interacting systems. Our program has been: To study energy, mass, and angular momentum deposition by studying incomplete fusion reactions. To gain confidence that we understand how highly excited systems decompose by studying all emissions from the highly excited systems. To push these kinds of studies into the intermediate energy domain, with excitation function studies. And attempt to learn about the dynamics of the decays using particle-particle correlations. In the last effort, we have decided to focus on simple systems, where we believe, definitive statements are possible. These avenues of research share a common theme, large complex fragment production.

  2. Isobaric Analogue States Studied in Mirrored Fragmentation and Knockout Reactions

    SciTech Connect

    Bentley, M.A.; Pritychenko, B.; Paterson,I.; Brown,J.R.; Taylor,M.J.; Digen,C.Aa.; Adrich,P.; Bazin,D.; Cook.J.M.; Gade,A.; Glasmacher,T.; McDaniel,S.; Ratkiewicz,A.; Siwek,K.; D.Weisshaar,D.; Pritychenko,B.; Lenzi,S.M.

    2010-05-21

    A Gamma-ray spectroscopic study of excited states of isobaric multiplets has been performed in recent years, with a view to gaining a quantitative understanding of energy differences between excited states in terms of a range of Coulomb and other isospin breaking phenomena. Recently, the experimental programme has been augmented by a study of isobaric analogue states of mirror nuclei populated in mirrored fragmentation reactions. In this presentation, recent results on the T = 3/2 analogue states in the T{sub z} = {+-} 3/2 mirror pair {sup 53}Ni/{sup 53}Mn will be summarised. In this work, further strong evidence is found for the need to include an anomalous isospin-breaking two-body matrix element for angular-momentum couplings of J = 2, in addition the expected Coulomb contribution, in order to account for the experimental data.

  3. Application of isochronous mass spectrometry for the study of angular momentum population in projectile fragmentation reactions

    NASA Astrophysics Data System (ADS)

    Tu, X. L.; Kelić-Heil, A.; Litvinov, Yu. A.; Podolyák, Zs.; Zhang, Y. H.; Huang, W. J.; Xu, H. S.; Blaum, K.; Bosch, F.; Chen, R. J.; Chen, X. C.; Fu, C. Y.; Gao, B. S.; Ge, Z.; Hu, Z. G.; Liu, D. W.; Litvinov, S. A.; Ma, X. W.; Mao, R. S.; Mei, B.; Shuai, P.; Sun, B. H.; Sun, Y.; Sun, Z. Y.; Walker, P. M.; Wang, M.; Winckler, N.; Xia, J. W.; Xiao, G. Q.; Xing, Y. M.; Xu, X.; Yamaguchi, T.; Yan, X. L.; Yang, J. C.; Yuan, Y. J.; Zeng, Q.; Zhang, W.; Zhao, H. W.; Zhao, T. C.; Zhou, X. H.

    2017-01-01

    Isochronous mass spectrometry was applied to measure isomeric yield ratios of fragmentation reaction products. This approach is complementary to conventional γ -ray spectroscopy in particular for measuring yield ratios for long-lived isomeric states. Isomeric yield ratios for the high-spin I =19 /2 ℏ states in the mirror nuclei 53Fe and 53Co are measured to study angular momentum population following the projectile fragmentation of 78Kr at energies of ˜480 A MeV on a beryllium target. The 19/2 state isomeric ratios of 53Fe produced from different projectiles in the literature have also been extracted as a function of mass number difference between projectile and fragment (mass loss). The results are compared to abrabla07 model calculations. The isomeric ratios of 53Fe produced using different projectiles suggest that the theory underestimates not only the previously reported dependence on the spin but also the dependence on the mass loss.

  4. Theoretical Study of Projectile Fragmentations in Relativistic Heavy-Ion Reactions

    NASA Astrophysics Data System (ADS)

    Ogul, R.; Imal, H.; Ergun, A.; Buyukcizmeci, N.; Botvina, A. S.; Trautmann, W.

    2015-05-01

    We have investigated and interpreted the production cross sections and isotopic distributions of projectile-like residues in the reactions 124Sn + 124Sn and 112Sn + 112Sn at an incident beam energy of 1 GeV/nucleon measured with the FRS fragment separator at the GSI laboratory. For the interpretation of the data, calculations within the statistical multifragmentation model (SMM) for an ensemble of excited sources were performed with ensemble parameters. The possible modification of symmetry energy parameter, in the multifragmentation region at the low density and hot freeze-out environment, is studied. It is reconfirmed that a significant reduction of the symmetry energy term is found necessary to reproduce experimental results at these conditions. We have also found a decreasing trend of the symmetry energy for large neutron-rich fragments of low excitation energy which is interpreted as a nuclear-structure effect.

  5. Collision induced dissociation study of ester-based polyurethane fragmentation reactions.

    PubMed

    Gies, Anthony P; Hercules, David M

    2014-01-15

    A combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) collision induced dissociation (CID) and ion mobility separations (IMS) was used to study a complex mixture composed of unreacted polyester starting material (polybutylene adipate) and polyurethane (PUR) end products. Collision induced dissociation fragmentation identified two primary fragmentation mechanisms of PURs, which were used to generate a general fragmentation model. Predicted fragment ions were used to distinguish: (1) linear and cyclic PURs, (2) hard-block and soft-block PURS, (3) the degree of "blockiness" within hard- and soft-block PURs, (4) the location of the MDI linkages within each PUR chain, and (5) the relative intensities of various isobars intermingled within a precursor mass peak. These results were consistent with the observed IMS separations.

  6. Study of near-stability nuclei populated as fission fragments in heavy-ion fusion reactions

    SciTech Connect

    Fotiadis, Nikolaos; Nelson, Ronald O; Devlin, Matthew; Cizewski, Jolie A; Krucken, Reiner; Clark, R M; Fallon, Paul; Lee, I Yang; Macchiavelli, Agusto O; Becker, John A; Younes, Walid

    2010-01-01

    Examples are presented to illustrate the power of prompt {gamma}-ray spectroscopy of fission fragments from compound nuclei with A {approx} 200 formed in fusion-evaporation reactions in experiments using the Gammasphere Ge-detector array. Complementary methods, such as Coulomb excitation and deep-inelastic processes, are also discussed. In other cases (n, xn{gamma}) reactions on stable isotopes have been used to establish neutron excitation functions for {gamma}-rays using a pulsed 'white'-neutron source, coupled to a high-energy-resolution germanium-detector array. The excitation functions can unambiguously assign {gamma}-rays to a specific reaction product. Results from all these methods bridge the gaps in the systematics of high-spin states between the neutron-deficient and neutron-rich nuclei. Results near shell closures should motivate new shell model calculations.

  7. A study to control chemical reactions using Si:2p core ionization: site-specific fragmentation.

    PubMed

    Nagaoka, Shin-ichi; Fukuzawa, Hironobu; Prümper, Georg; Takemoto, Mai; Takahashi, Osamu; Yamaguchi, Katsuhiro; Kakiuchi, Takuhiro; Tabayashi, Kiyohiko; Suzuki, Isao H; Harries, James R; Tamenori, Yusuke; Ueda, Kiyoshi

    2011-08-18

    In an aim to create a "sharp" molecular knife, we have studied site-specific fragmentation caused by Si:2p core photoionization of bridged trihalosilyltrimethylsilyl molecules in the vapor phase. Highly site-specific bond dissociation has been found to occur around the core-ionized Si site in some of the molecules studied. The site specificity in fragmentation and the 2p binding energy difference between the two Si sites depend in similar ways on the intersite bridge and the electronegativities of the included halogen atoms. The present experimental and computational results show that for efficient "cutting" the following conditions for the two atomic sites to be separated by the knife should be satisfied. First, the sites should be located far from each other and connected by a chain of saturated bonds so that intersite electron migration can be reduced. Second, the chemical environments of the atomic sites should be as different as possible.

  8. Studies of complex fragment emission in heavy ion reactions. Progress report, January 1, 1993--September 15, 1993

    SciTech Connect

    Charity, R.J.; Sobotka, L.G.

    1993-09-12

    The study of intermediate-energy heavy-ion nuclear reactions is reported. This work has two foci: the properties of nuclear matter under abnormal conditions, in this energy domain, predominately low densities and the study of the relevant reaction mechanisms. Nuclear matter properties, such as phase transitions, are reflected in the dynamics of the reactions. The process leads to an understanding of the reaction mechanism themselves and therefore to the response characteristics of finite, perhaps non-equilibrium, strongly interacting systems. The program has the following objectives: to study energy, mass, and angular momentum deposition by studying incomplete fusion reactions; to gain confidence in the understanding of how highly excited systems decompose by studying all emissions from the highly excited systems; to push these kinds of studies into the intermediate energy domain (where intermediate mass fragment emission is not improbable) with excitation function studies; and to learn about the dynamics of the decays using particle-particle correlations. The last effort focuses on simple systems, where definitive statements are possible. These avenues of research share a common theme, large complex fragment production. It is this feature, more than any other, which distinguishes the intermediate energy domain.

  9. Application of restriction fragment differential display-polymerase chain reaction in study on differential expression profiles of human diseases.

    PubMed

    Zhou, Hong-ying; Mei, Yan; Lu, You-guang; Li, Ai-dong; Tang, En-jie; Yang, Hui-jun

    2005-06-01

    To establish the restriction fragment differential display-polymerase chain reaction (RFDD-PCR) as an efficient technique for constructing and studying the gene expression profile of human tissues. The tissues of mamma adenocarcinoma (T), cancerometastasis lymph node (L) and normal mammary (N) from one mammary infiltrating ductal carcinoma case were collected, and the gene expression profile of each kind of tissue was constructed using RFDD-PCR technique at equal pace according to the operating manual of Qbio-gene Company. Then all fragments of the three gene expression profiles were separated and displayed by electrophoresis. With the use of gene database at the website http://www.Qbio-gene.com/display, the authors identified the names of the probable fragments by bioinformatics analysis. Through comparison of the three profiles, the numbers and types of most differentially expressed gene fragments were displayed. The expression profiles of the three kinds of tissue have been constructed covering 1716 fragments of mammary adenocarcinoma, 1769 of cancerometastasis lymph nodes and 1922 of normal mammary tissue. Among these 5407 fragments, 39.39% were exactly the same. While 33.9% sequences of T and L showed differences in abundance or presence, 40.9% of T and N and 39.6% fragments of L and N were observed differentially expressed. These differentially expressed gene fragments were found to relate with metastasis, differentiation, inflammation and so on. RFDD-PCR is an efficient technique for research in human diseases genomics as a mass screening for complete gene expression profile with high-flux. Through comparison among three or more profiles, the screening for candidate genes of a certain disease can be accomplished, and there is probably a chance to identify novel gene or expressed sequence tag.

  10. Study on Fragments Emission in the 64Ni + 64Ni Reaction at 40 AMeV

    NASA Astrophysics Data System (ADS)

    Yang, Kun; Cao, Xiguang; Shi, Fudong; Liu, Xingquan; Zhang, Suyalatu; Huang, Meirong; Wang, Jiansong; Chen, Zhiqiang; Wada, R.; Kowalski, S.; Keutgen, T.; Hagel, K.; Bonasera, A.; B. Natowitz, J.; Materna, T.; L., Qin; K. Sahu, P.

    2012-05-01

    The multiplicity of fragments in Fermi energy heavy-ion collisions was experimentally extracted. Compared with the results of calculation using the antisymmetrized molecular dynamics (AMD) model which accounts for the primary fragments only, the results calculated using the AMD together with a statistical decay code GEMINI to account for the deexcitation of excited primary fragments are in better agreement with those extracted from the experiment. This observation indicates that the experimental multiplicity distribution may be significantly different from those of primary fragments.

  11. Studies of complex fragment emission in heavy ion reactions. Progress report, January 1, 1990--August 5, 1992

    SciTech Connect

    Charity, R.J.; Sobotka, L.G.

    1992-09-01

    Our work involves the study of intermediate energy heavy-ion nuclear reactions. This work has two foci. On the one hand, we desire to learn about the properties of nuclear matter under abnormal conditions, in this energy domain, predominately low densities. This purpose runs abreast of the second, which is the study of the relevant reaction mechanisms. The two objectives are inexorably linked because our experimental laboratory for studying nuclear matter properties is a dynamic one. We are forced to ask how nuclear matter properties, such as phase transitions, are reflected in the dynamics of the reactions. It may be that irrefutable information about nuclear matter will not be extracted from the reaction work. Nevertheless, we are compelled to undertake this effort not only because it is the only game in town and as yet we do not know that information cannot be extracted, but also because of our second objective. The process leads to an understanding of the reaction mechanism themselves and therefore to the response characteristics of finite, perhaps non-equilibrium, strongly interacting systems. Our program has been: To study energy, mass, and angular momentum deposition by studying incomplete fusion reactions. To gain confidence that we understand how highly excited systems decompose by studying all emissions from the highly excited systems. To push these kinds of studies into the intermediate energy domain, with excitation function studies. And attempt to learn about the dynamics of the decays using particle-particle correlations. In the last effort, we have decided to focus on simple systems, where we believe, definitive statements are possible. These avenues of research share a common theme, large complex fragment production.

  12. Barrierless electron transfer bond fragmentation reactions.

    PubMed

    Lorance, Edward D; Kramer, Wolfgang H; Gould, Ian R

    2004-11-03

    The ultrafast N-O bond fragmentation in a series of N-methoxypyridyl radicals, formed by one-electron reduction of the corresponding N-methoxypyridiniums, has been investigated as potentially barrierless electron-transfer-initiated chemical reactions. A model for the reaction involving the electronic and geometric factors that control the shape of the potential energy surface for the reaction is described. On the basis of this model, molecular structural features appropriate for ultrafast reactivity are proposed. Femtosecond kinetic measurements on these reactions are consistent with a kinetic definition of an essentially barrierless reaction, i.e., that the lifetime of the radical is a few vibrational periods of the fragmenting bond, for the p-methoxy-N-methoxypyridyl radical.

  13. An Investigation of Fragments Produced in the 58,64Ni + 9Be Fragmentation Reactions

    NASA Astrophysics Data System (ADS)

    Zhang, Y. L.; Ma, C. W.; Wang, S. S.; Qiao, C. Y.

    The cross sections of the fragments produced in the 140A MeV 58,64Ni + 9Be reactions have been studied using the empirical parametrization formula EPAX2 and EPAX3, the modified statistical abrasion-ablation (SAA) model, and the antisymmetrized molecular dynamics (AMD) model. The calculated cross sections of fragments are compared and discussed.

  14. Fragmentation reactions of deprotonated peptides containing aspartic acid

    NASA Astrophysics Data System (ADS)

    Harrison, Alex G.; Young, Alex B.

    2006-09-01

    The fragmentation reactions of deprotonated peptides containing aspartic acid have been elucidated using MS2 and MS3 experiments and accurate mass measurements where necessary. The disposition of labile (N and O bonded) hydrogens in the fragmentation products has been studied by exchanging the labile hydrogens for deuterium whereby the [MD]- ion is formed on electrospray ionization. [alpha]-Aspartyl and [beta]-aspartyl dipeptides give very similar fragment ion spectra on collisional activation, involving for both species primarily formation of the y1 ion and loss of H2O from [MH]- followed by further fragmentation, thus precluding the distinction of the isomeric species by negative ion tandem mass spectrometry. Dipeptides of sequence HXxxAspOH give characteristic spectra different from the [alpha]- and [beta]-isomers. For larger peptides containing aspartic acid a common fragmentation reaction involves nominal cleavage of the NC bond N-terminal to the aspartic acid residue to form a c ion (deprotonated amino acid amide (c1) or peptide amide (cn)) and the complimentary product involving elimination of a neutral amino acid amide or peptide amide. When aspartic acid is in the C-terminal position this fragmentation reaction occurs from the [MH]- ion while when the aspartic acid is not in the C-terminal position the fragmentation reaction occurs mainly from the [MHH2O]- ion. The products of this NC bond cleavage reaction serve to identify the position of the aspartic acid residue in the peptide.

  15. [Fragment reaction catalyzed by E. coli ribosomes].

    PubMed

    Kotusov, V V; Kukhanova, M K; Sal'nikova, N E; Nikolaeva, L V; Kraevskiĭ, A A

    1977-01-01

    It has been shown that 50S subunits of E. coli MRE-600 ribosomes catalyze the reaction of N-(formyl)-methionyl ester of adenosine 5'-phosphate acting as peptide donor, with Phe-tRNA or CACCA-Phe serving as a peptide acceptor. The reaction is stimulated by cytidine 5'phosphate and inhibited by lincomycin, puromycin and chloramphenicol. The obtained results show that the structure of the donor site of peptidyltransferase is completely assembled on the 50S subunit and 30S subunit is not required for its formation.

  16. Theoretical Study of the Reaction Formalhydrazone with Singlet Oxygen. Fragmentation of the C=N Bond, Ene Reaction, and Other Processes†

    PubMed Central

    Rudshteyn, Benjamin; Castillo, Álvaro; Ghogare, Ashwini A.; Liebman, Joel F.; Greer, Alexander

    2013-01-01

    Photobiologic and synthetic versatility of hydrazones has not yet been established with 1O2 as a route to commonly encountered nitrosamines. Thus, to determine whether the “parent” reaction of formalhydrazone and 1O2 leads to facile C=N bond cleavage and resulting nitrosamine formation, we have carried out CCSD(T)//DFT calculations and analyzed the energetics of the oxidation pathways. A [2 + 2] pathway occurs via diradicals and formation of 3-amino-1,2,3-dioxazetidine in a 16 kcal/mol process. Reversible addition or physical quenching of 1O2 occurs either on the formalhydrazone carbon for triplet diradicals at 2–3 kcal/mol, or on the nitrogen (N(3)) atom forming zwitterions at ~15 kcal/mol, although the quenching channel by charge-transfer interaction was not computed. The computations also predict a facile conversion of formalhydrazone and 1O2 to hydroperoxymethyl diazene in a low-barrier ‘ene’ process, but no 2-amino-oxaziridine-O-oxide (perepoxide-like) intermediate was found. A Benson-like analysis (group increment calculations) on the closed shell species are in accord with the quantum chemical results. PMID:24354600

  17. Fragmentation reactions of protonated peptides containing glutamine or glutamic acid.

    PubMed

    Harrison, Alex G

    2003-02-01

    A variety of protonated dipeptides and tripeptides containing glutamic acid or glutamine were prepared by electrospray ionization or by fast atom bombardment ionization and their fragmentation pathways elucidated using metastable ion studies, energy-resolved mass spectrometry and triple-stage mass spectrometry (MS(3)) experiments. Additional mechanistic information was obtained by exchanging the labile hydrogens for deuterium. Protonated H-Gln-Gly-OH fragments by loss of NH(3) and loss of H(2)O in metastable ion fragmentation; under collision-induced dissociation (CID) conditions loss of H-Gly-OH + CO from the [MH - NH(3)](+) ion forms the base peak C(4)H(6)NO(+) (m/z 84). Protonated dipeptides with an alpha-linkage, H-Glu-Xxx-OH, are characterized by elimination of H(2)O and by elimination of H-Xxx-OH plus CO to form the glutamic acid immonium ion of m/z 102. By contrast, protonated dipeptides with a gamma-linkage, H-Glu(Xxx-OH)-OH, do not show elimination of H(2)O or formation of m/z 102 but rather show elimination of NH(3), particularly in metastable ion fragmentation, and elimination of H-Xxx-OH to form m/z 130. Both the alpha- and gamma-dipeptides show formation of [H-Xxx-OH]H(+), with this reaction channel increasing in importance as the proton affinity (PA) of H-Xxx-OH increases. The characteristic loss of H(2)O and formation of m/z 102 are observed for the protonated alpha-tripeptide H-Glu-Gly-Phe-OH whereas the protonated gamma-tripeptide H-Glu(Gly-Gly-OH)-OH shows loss of NH(3) and formation of m/z 130 as observed for dipeptides with the gamma-linkage. Both tripeptides show abundant formation of the y(2)'' ion under CID conditions, presumably because a stable anhydride neutral structure can be formed. Under metastable ion conditions protonated dipeptides of structure H-Xxx-Glu-OH show abundant elimination of H(2)O whereas those of structure H-Xxx-Gln-OH show abundant elimination of NH(3). The importance of these reaction channels is much reduced under CID

  18. Cloning of DNA fragments: ligation reactions in agarose gel.

    PubMed

    Furtado, Agnelo

    2014-01-01

    Ligation reactions to ligate a desired DNA fragment into a vector can be challenging to beginners and especially if the amount of the insert is limiting. Although additives known as crowding agents, such as PEG 8000, added to the ligation mixes can increase the success one has with ligation reactions, in practice the amount of insert used in the ligation can determine the success or the failure of the ligation reaction. The method described here, which uses insert DNA in gel slice added directly into the ligation reaction, has two benefits: (a) using agarose as the crowding agent and (b) reducing steps of insert purification. The use of rapid ligation buffer and incubation of the ligation reaction at room temperature greatly increase the efficiency of the ligation reaction even for blunt-ended ligation.

  19. RxnFinder: biochemical reaction search engines using molecular structures, molecular fragments and reaction similarity.

    PubMed

    Hu, Qian-Nan; Deng, Zhe; Hu, Huanan; Cao, Dong-Sheng; Liang, Yi-Zeng

    2011-09-01

    Biochemical reactions play a key role to help sustain life and allow cells to grow. RxnFinder was developed to search biochemical reactions from KEGG reaction database using three search criteria: molecular structures, molecular fragments and reaction similarity. RxnFinder is helpful to get reference reactions for biosynthesis and xenobiotics metabolism. RxnFinder is freely available via: http://sdd.whu.edu.cn/rxnfinder. qnhu@whu.edu.cn.

  20. Comparative study of Mycobacterium paratuberculosis strains isolated from Crohn's disease and Johne's disease using restriction fragment length polymorphism and arbitrarily primed polymerase chain reaction.

    PubMed Central

    François, B.; Krishnamoorthy, R.; Elion, J.

    1997-01-01

    To obtain insights into the pathogenic mechanisms involving Mycobacterium paratuberculosis in Crohn's disease (CD) we questioned if the strains of M. paratuberculosis isolated from CD are distinguishable from those involved in Johne's disease (JD), a chronic granulomatous enteritis in cattle. Accordingly we compared human and animal strains at the DNA level, both by the analysis of restriction fragment length polymorphism (RFLP) in and around the insertion sequence IS 900 and by the arbitrarily primed chain reaction (AP-PCR). Results are in favour of a common clonal origin for the 4 strains isolated from CD and for 8 of the 11 strains isolated from cattle and sheep JD. PMID:9207733

  1. Structural Studies of Geosmin Synthase, a Bifunctional Sesquiterpene Synthase with αα Domain Architecture That Catalyzes a Unique Cyclization-Fragmentation Reaction Sequence.

    PubMed

    Harris, Golda G; Lombardi, Patrick M; Pemberton, Travis A; Matsui, Tsutomu; Weiss, Thomas M; Cole, Kathryn E; Köksal, Mustafa; Murphy, Frank V; Vedula, L Sangeetha; Chou, Wayne K W; Cane, David E; Christianson, David W

    2015-12-08

    Geosmin synthase from Streptomyces coelicolor (ScGS) catalyzes an unusual, metal-dependent terpenoid cyclization and fragmentation reaction sequence. Two distinct active sites are required for catalysis: the N-terminal domain catalyzes the ionization and cyclization of farnesyl diphosphate to form germacradienol and inorganic pyrophosphate (PPi), and the C-terminal domain catalyzes the protonation, cyclization, and fragmentation of germacradienol to form geosmin and acetone through a retro-Prins reaction. A unique αα domain architecture is predicted for ScGS based on amino acid sequence: each domain contains the metal-binding motifs typical of a class I terpenoid cyclase, and each domain requires Mg(2+) for catalysis. Here, we report the X-ray crystal structure of the unliganded N-terminal domain of ScGS and the structure of its complex with three Mg(2+) ions and alendronate. These structures highlight conformational changes required for active site closure and catalysis. Although neither full-length ScGS nor constructs of the C-terminal domain could be crystallized, homology models of the C-terminal domain were constructed on the basis of ∼36% sequence identity with the N-terminal domain. Small-angle X-ray scattering experiments yield low-resolution molecular envelopes into which the N-terminal domain crystal structure and the C-terminal domain homology model were fit, suggesting possible αα domain architectures as frameworks for bifunctional catalysis.

  2. Structural Studies of Geosmin Synthase, a Bifunctional Sesquiterpene Synthase with Alpha-Alpha Domain Architecture that Catalyzes a Unique Cyclization-Fragmentation Reaction Sequence

    PubMed Central

    Harris, Golda G.; Lombardi, Patrick M.; Pemberton, Travis A.; Matsui, Tsutomu; Weiss, Thomas M.; Cole, Kathryn E.; Köksal, Mustafa; Murphy, Frank V.; Vedula, L. Sangeetha; Chou, Wayne K.W.; Cane, David E.; Christianson, David W.

    2015-01-01

    Geosmin synthase from Streptomyces coelicolor (ScGS) catalyzes an unusual, metal-dependent terpenoid cyclization and fragmentation reaction sequence. Two distinct active sites are required for catalysis: the N-terminal domain catalyzes the ionization and cyclization of farnesyl diphosphate to form germacradienol and inorganic pyrophosphate (PPi), and the C-terminal domain catalyzes the protonation, cyclization, and fragmentation of germacradienol to form geosmin and acetone through a retro-Prins reaction. A unique αα domain architecture is predicted for ScGS based on amino acid sequence: each domain contains the metal-binding motifs typical of a class I terpenoid cyclase, and each domain requires Mg2+ for catalysis. Here, we report the X-ray crystal structure of the unliganded N-terminal domain of ScGS and the structure of its complex with 3 Mg2+ ions and alendronate. These structures highlight conformational changes required for active site closure and catalysis. Although neither full-length ScGS nor constructs of the C-terminal domain could be crystallized, homology models of the C-terminal domain were constructed based on ~36% sequence identity with the N-terminal domain. Small-angle X-ray scattering experiments yield low resolution molecular envelopes into which the N-terminal domain crystal structure and the C-terminal domain homology model were fit, suggesting possible αα domain architectures as frameworks for bifunctional catalysis. PMID:26598179

  3. Photodegradable, Photoadaptable Hydrogels via Radical-Mediated Disulfide Fragmentation Reaction

    PubMed Central

    2011-01-01

    Various techniques have been adopted to impart a biological responsiveness to synthetic hydrogels for the delivery of therapeutic agents as well as the study and manipulation of biological processes and tissue development. Such techniques and materials include polyelectrolyte gels that swell and deswell with changes in pH, thermosensitive gels that contract at physiological temperatures, and peptide cross-linked hydrogels that degrade upon peptidolysis by cell-secreted enzymes. Herein we report a unique approach to photochemically deform and degrade disulfide cross-linked hydrogels, mitigating the challenges of light attenuation and low quantum yield, permitting the degradation of hydrogels up to 2 mm thick within 120 s at low light intensities (10 mW/cm2 at 365 nm). Hydrogels were formed by the oxidation of thiol-functionalized 4-armed poly(ethylene glycol) macromolecules. These disulfide cross-linked hydrogels were then swollen in a lithium acylphosphinate photoinitiator solution. Upon exposure to light, photogenerated radicals initiate multiple fragmentation and disulfide exchange reactions, permitting and promoting photodeformation, photowelding, and photodegradation. This novel, but simple, approach to generate photoadaptable hydrogels portends the study of cellular response to mechanically and topographically dynamic substrates as well as novel encapsulations by the welding of solid substrates. The principles and techniques described herein hold implications for more than hydrogel materials but also for photoadaptable polymers more generally. PMID:21512614

  4. Dissertation: Precompound Emission of Energetic Light Fragments in Spallation Reactions

    SciTech Connect

    Kerby, Leslie Marie

    2015-08-04

    Emission of light fragments (LF) from nuclear reactions is an open question. Different reaction mechanisms contribute to their production; the relative roles of each, and how they change with incident energy, mass number of the target, and the type and emission energy of the fragments is not completely understood. None of the available models are able to accurately predict emission of LF from arbitrary reactions. However, the ability to describe production of LF (especially at energies ≳ 30 MeV) from many reactions is important for different applications, such as cosmic-ray-induced Single Event Upsets (SEUs), radiation protection, and cancer therapy with proton and heavy-ion beams, to name just a few. The Cascade-Exciton Model (CEM) version 03.03 and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) version 03.03 event generators in Monte Carlo N-Particle Transport Code version 6 (MCNP6) describe quite well the spectra of fragments with sizes up to ⁴He across a broad range of target masses and incident energies (up to ~ 5 GeV for CEM and up to ~ 1 TeV/A for LAQGSM). However, they do not predict the high energy tails of LF spectra heavier than ⁴He well. Most LF with energies above several tens of MeV are emitted during the precompound stage of a reaction. The current versions of the CEM and LAQGSM event generators do not account for precompound emission of LF larger than ⁴He. The aim of our work is to extend the precompound model in them to include such processes, leading to an increase of predictive power of LF-production in MCNP6. This entails upgrading the Modified Exciton Model currently used at the preequilibrium stage in CEM and LAQGSM. It also includes expansion and examination of the coalescence and Fermi break-up models used in the precompound stages of spallation reactions within CEM and LAQGSM. Extending our models to include emission of fragments heavier than ⁴He at the precompound stage has indeed provided results that have much

  5. Precompound emission of energetic light fragments in spallation reactions

    NASA Astrophysics Data System (ADS)

    Kerby, Leslie Marie

    Emission of light fragments (LF) from nuclear reactions is an open question. Different reaction mechanisms contribute to their production; the relative roles of each, and how they change with incident energy, mass number of the target, and the type and emission energy of the fragments is not completely understood. None of the available models are able to accurately predict emission of LF from arbitrary reactions. However, the ability to describe production of LF (especially at energies ~ 30 MeV) from many reactions is important for different applications, such as cosmic-ray-induced Single Event Upsets (SEUs), radiation protection, and cancer therapy with proton and heavy-ion beams, to name just a few. The Cascade-Exciton Model (CEM) version 03.03 and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) version 03.03 event generators in Monte Carlo N-Particle Transport Code version 6 (MCNP6) describe quite well the spectra of fragments with sizes up to 4He across a broad range of target masses and incident energies (up to ~ 5 GeV for CEM and up to ~1 TeV/A for LAQGSM). However, they do not predict the high-energy tails of LF spectra heavier than 4He well. Most LF with energies above several tens of MeV are emitted during the precompound stage of a reaction. The current versions of the CEM and LAQGSM event generators do not account for precompound emission of LF larger than 4He. The aim of our work is to extend the precompound model in them to include such processes, leading to an increase of predictive power of LF-production in MCNP6. This entails upgrading the Modified Exciton Model currently used at the preequilibrium stage in CEM and LAQGSM. It also includes expansion and examination of the coalescence and Fermi break-up models used in the precompound stages of spallation reactions within CEM and LAQGSM. Extending our models to include emission of fragments heavier than 4He at the precompound stage has indeed provided results that have much better

  6. A population genetics study of Anopheles darlingi (Diptera: Culicidae) from Colombia based on random amplified polymorphic DNA-polymerase chain reaction and amplified fragment lenght polymorphism markers.

    PubMed

    González, Ranulfo; Wilkerson, Richard; Suárez, Marco Fidel; García, Felipe; Gallego, Gerardo; Cárdenas, Heiber; Posso, Carmen Elisa; Duque, Myriam Cristina

    2007-06-01

    The genetic variation and population structure of three populations of Anopheles darlingi from Colombia were studied using random amplified polymorphic markers (RAPDs) and amplified fragment length polymorphism markers (AFLPs). Six RAPD primers produced 46 polymorphic fragments, while two AFLP primer combinations produced 197 polymorphic fragments from 71 DNA samples. Both of the evaluated genetic markers showed the presence of gene flow, suggesting that Colombian An. darlingi populations are in panmixia. Average genetic diversity, estimated from observed heterozygosity, was 0.374 (RAPD) and 0.309 (AFLP). RAPD and AFLP markers showed little evidence of geographic separation between eastern and western populations; however, the F ST values showed high gene flow between the two western populations (RAPD: F ST = 0.029; Nm: 8.5; AFLP: F ST = 0.051; Nm: 4.7). According to molecular variance analysis (AMOVA), the genetic distance between populations was significant (RAPD:phiST = 0.084; AFLP:phiST = 0.229, P < 0.001). The F ST distances and AMOVAs using AFLP loci support the differentiation of the Guyana biogeographic province population from those of the Chocó-Magdalena. In this last region, Chocó and Córdoba populations showed the highest genetic flow.

  7. Proton Mobility in b2 Ion Formation and Fragmentation Reactions of Histidine-Containing Peptides

    NASA Astrophysics Data System (ADS)

    Nelson, Carissa R.; Abutokaikah, Maha T.; Harrison, Alex G.; Bythell, Benjamin J.

    2016-03-01

    A detailed energy-resolved study of the fragmentation reactions of protonated histidine-containing peptides and their b2 ions has been undertaken. Density functional theory calculations were utilized to predict how the fragmentation reactions occur so that we might discern why the mass spectra demonstrated particular energy dependencies. We compare our results to the current literature and to synthetic b2 ion standards. We show that the position of the His residue does affect the identity of the subsequent b2 ion (diketopiperazine versus oxazolone versus lactam) and that energy-resolved CID can distinguish these isomeric products based on their fragmentation energetics. The histidine side chain facilitates every major transformation except trans-cis isomerization of the first amide bond, a necessary prerequisite to diketopiperazine b2 ion formation. Despite this lack of catalyzation, trans-cis isomerization is predicted to be facile. Concomitantly, the subsequent amide bond cleavage reaction is rate-limiting.

  8. Proton Mobility in b₂ Ion Formation and Fragmentation Reactions of Histidine-Containing Peptides.

    PubMed

    Nelson, Carissa R; Abutokaikah, Maha T; Harrison, Alex G; Bythell, Benjamin J

    2016-03-01

    A detailed energy-resolved study of the fragmentation reactions of protonated histidine-containing peptides and their b2 ions has been undertaken. Density functional theory calculations were utilized to predict how the fragmentation reactions occur so that we might discern why the mass spectra demonstrated particular energy dependencies. We compare our results to the current literature and to synthetic b2 ion standards. We show that the position of the His residue does affect the identity of the subsequent b2 ion (diketopiperazine versus oxazolone versus lactam) and that energy-resolved CID can distinguish these isomeric products based on their fragmentation energetics. The histidine side chain facilitates every major transformation except trans-cis isomerization of the first amide bond, a necessary prerequisite to diketopiperazine b2 ion formation. Despite this lack of catalyzation, trans-cis isomerization is predicted to be facile. Concomitantly, the subsequent amide bond cleavage reaction is rate-limiting.

  9. Simulations of Chemical Reactions with the Frozen Domain Formulation of the Fragment Molecular Orbital Method.

    PubMed

    Nakata, Hiroya; Fedorov, Dmitri G; Nagata, Takeshi; Kitaura, Kazuo; Nakamura, Shinichiro

    2015-07-14

    The fully analytic first and second derivatives of the energy in the frozen domain formulation of the fragment molecular orbital (FMO) were developed and applied to locate transition states and determine vibrational contributions to free energies. The development is focused on the frozen domain with dimers (FDD) model. The intrinsic reaction coordinate method was interfaced with FMO. Simulations of IR and Raman spectra were enabled using FMO/FDD by developing the calculation of intensities. The accuracy is evaluated for S(N)2 reactions in explicit solvent, and for the free binding energies of a protein-ligand complex of the Trp cage protein (PDB: 1L2Y ). FMO/FDD is applied to study the keto-enol tautomeric reaction of phosphoglycolohydroxamic acid and the triosephosphate isomerase (PDB: 7TIM ), and the role of amino acid residue fragments in the reaction is discussed.

  10. Scaling phenomena of isobaric yields in projectile fragmentation, spallation, and fission reactions

    NASA Astrophysics Data System (ADS)

    Ma, Chun-Wang; Huang, Ling; Song, Yi-Dan

    2017-02-01

    Background: The isobaric ratio difference scaling phenomenon, which has been found for the fragments produced in projectile fragmentation reactions, is related to the nuclear density change in reaction systems. Purpose: To verify whether the isobaric ratio difference scaling exists in the fragments produced in the spallation and fission reactions. Methods: The isobaric ratio difference scaling, denoted by SΔ lnR21 , is in theory deduced within the framework of the canonical ensemble theory at the grand-canonical limitation. The fragments measured in a series of projectile fragmentation, spallation, and fission reactions have been analyzed. Results: A good SΔ lnR21 scaling phenomenon is shown for the fragments produced both in the projectile fragmentation reactions and in the spallation reactions, whereas the SΔ lnR21 scaling phenomenon for the fragments in the fission reaction is less obvious. Conclusions: The SΔ lnR21 scaling is used to probe the properties of the equilibrium system at the time of fragment formation. The good scaling of SΔ lnR21 suggests that the equilibrium state can be achieved in the projectile fragmentation and spallation reactions. Whereas in the fission reaction, the result of SΔ lnR21 indicates that the equilibrium of the system is hard to achieve.

  11. Mirrored Fragmentation Reactions--A New Technique for Probing Isospin Symmetry in Exotic Nuclei

    SciTech Connect

    Brown, J. R.; Bentley, M. A.; Taylor, M. J.; Aldrich, P.; Bazin, D.; Cook, J. M.; Diget, C. A.; Gade, A.; Glasmacher, T.; McDaniel, S. M.; Ratkiewicz, A.; Siwek, K.; Weisshaar, D.; Pritychenko, B.

    2008-05-12

    Gamma decays have been observed for the first time in the T{sub z} = -3/2 nucleus {sup 53}Ni. This represents the first gamma-spectroscopy of a T{sub z} = -3/2 nucleus heavier than A = 33. The nucleus was produced via a two-step fragmentation process, along with its mirror {sup 53}Mn. Differences in excitation energy between isobaric analogue states have been calculated and a preliminary interpretation attempted; shell model calculations are required to further understand these results. This work represents the first study of isobaric analogue states via mirrored fragmentation reactions and demonstrates the power of this new technique.

  12. Things fall apart: Fragmentation reactions in the oxidative aging of organic species

    NASA Astrophysics Data System (ADS)

    Kroll, J. H.; Isaacman-VanWertz, G. A.; Wilson, K. R.; Daumit, K. E.; Kessler, S. H.; Lim, C. Y.; Worsnop, D. R.

    2016-12-01

    The atmospheric oxidation of organic compounds involves a wide array of chemical transformations, including functionalization reactions (addition of polar functional groups to the carbon skeleton), fragmentation reactions (formation of lower carbon-number products via C-C bond scission), and accretion reactions (increases in molecular weight by the combination of two chemical species). Each of these reaction classes can lead to large changes in volatility, and hence can have major implications for atmospheric organic aerosol (OA). For example, the formation of OA is predominantly driven by functionalization and accretion reactions, which generally lead to decreases in volatility. Here we describe a series of laboratory studies of the subsequent organic "aging", the multiday oxidation processes that occur after the initial OA formation and growth. In these studies, the multigenerational oxidation of organic compounds in various phases (the gas phase, the condensed OA phase, and the aqueous phase) is carried out within either an environmental chamber or a flow reactor, and monitored using various high-resolution mass spectrometric techniques. In all cases it is found that fragmentation reactions play a major role in the observed aging chemistry, dominated by the formation of small, volatile oxidation products. These results suggest that multi-day oxidative aging processes do not lead to sustained aerosol growth, but rather may serve as a chemical sink for atmospheric OA.

  13. Nuclear fragmentation studies for microelectronic application

    NASA Technical Reports Server (NTRS)

    Ngo, Duc M.; Wilson, John W.; Buck, Warren W.; Fogarty, Thomas N.

    1989-01-01

    A formalism for target fragment transport is presented with application to energy loss spectra in thin silicon devices. Predicted results are compared to experiments with the surface barrier detectors of McNulty et al. The intranuclear cascade nuclear reaction model does not predict the McNulty experimental data for the highest energy events. A semiempirical nuclear cross section gives an adequate explanation of McNulty's experiments. Application of the formalism to specific electronic devices is discussed.

  14. Comparing the gas-phase fragmentation reactions of protonated and radical cations of the tripeptides GXR

    NASA Astrophysics Data System (ADS)

    Wee, Sheena; O'Hair, Richard A. J.; McFadyen, W. David

    2004-05-01

    Electrospray ionization (ESI) mass spectrometry of methanolic solutions of mixtures of the copper salt (2,2':6',2''-terpyridine)copper(II) nitrate monohydrate ([Cu(II)(tpy)(NO3)2].H2O) and a tripeptide GXR (where X = 1 of the 20 naturally occurring amino acids) yielded [Cu(II)(tpy)(GXR)][radical sign]2+ ions, which were then subjected to collision induced dissociation (CID). In all but one case (GRR), these [Cu(II)(tpy)(GXR)][radical sign]2+ ions fragment to form odd electron GXR[radical sign]+ radical cations with sufficient abundance to examine their gas-phase fragmentation reactions. The GXR[radical sign]+ radical cations undergo a diverse range of fragmentation reactions which depend on the nature of the side chain of X. Many of these reactions can be rationalized as arising from the intermediacy of isomeric distonic ions in which the charge (i.e. proton) is sequestered by the highly basic arginine side chain and the radical site is located at various positions on the tripeptide including the peptide back bone and side chains. The radical sites in these distonic ions often direct the fragmentation reactions via the expulsion of small radicals (to yield even electron ions) or small neutrals (to form radical cations). Both classes of reaction can yield useful structural information, allowing for example, distinction between leucine and isoleucine residues. The gas-phase fragmentation reactions of the GXR[radical sign]+ radical cations are also compared to their even electron [GXR+H]+ and [GXR+2H]2+ counterparts. The [GXR+H]+ ions give fewer sequence ions and more small molecule losses while the [GXR+2H]2+ ions yield more sequence information, consistent with the [`]mobile proton model' described in previous studies. In general, all three classes of ions give complementary structural information, but the GXR[radical sign]+ radical cations exhibit a more diverse loss of small species (radicals and neutrals). Finally, links between these gas-phase results and key

  15. Radiation induced redox reactions and fragmentation of constituent ions in ionic liquids. 1. Anions.

    PubMed

    Shkrob, Ilya A; Marin, Timothy W; Chemerisov, Sergey D; Wishart, James F

    2011-04-14

    Room temperature ionic liquids (IL) find increasing use for the replacement of organic solvents in practical applications, including their use in solar cells and electrolytes for metal deposition, and as extraction solvents for the reprocessing of spent nuclear fuel. The radiation stability of ILs is an important concern for some of these applications, as previous studies suggested extensive fragmentation of the constituent ions upon irradiation. In the present study, electron paramagnetic resonance (EPR) spectroscopy has been used to identify fragmentation pathways for constituent anions in ammonium, phosphonium, and imidazolium ILs. Many of these detrimental reactions are initiated by radiation-induced redox processes involving these anions. Scission of the oxidized anions is the main fragmentation pathway for the majority of the practically important anions; (internal) proton transfer involving the aliphatic arms of these anions is a competing reaction. For perfluorinated anions, fluoride loss following dissociative electron attachment to the anion can be even more prominent than this oxidative fragmentation. Bond scission in the anion was also observed for NO(3)(-) and B(CN)(4)(-) anions and indirectly implicated for BF(4)(-) and PF(6)(-) anions. Among small anions, CF(3)SO(3)(-) and N(CN)(2)(-) are the most stable. Among larger anions, the derivatives of benzoate and imide anions were found to be relatively stable. This stability is due to suppression of the oxidative fragmentation. For benzoates, this is a consequence of the extensive sharing of unpaired electron density by the π-system in the corresponding neutral radical; for the imides, this stability could be the consequence of N-N σ(2)σ(*1) bond formation involving the parent anion. While fragmentation does not occur for these "exceptional" anions, H atom addition and electron attachment are prominent. Among the typically used constituent anions, aliphatic carboxylates were found to be the least

  16. Radiation induced redox reactions and fragmentation of constituent ions in ionic liquids. I. Anions.

    SciTech Connect

    Shkrob, I. A.; Marin, T.; Chemerisov, S.; Wishart, J.

    2011-04-14

    Room temperature ionic liquids (IL) find increasing use for the replacement of organic solvents in practical applications, including their use in solar cells and electrolytes for metal deposition, and as extraction solvents for the reprocessing of spent nuclear fuel. The radiation stability of ILs is an important concern for some of these applications, as previous studies suggested extensive fragmentation of the constituent ions upon irradiation. In the present study, electron paramagnetic resonance (EPR) spectroscopy has been used to identify fragmentation pathways for constituent anions in ammonium, phosphonium, and imidazolium ILs. Many of these detrimental reactions are initiated by radiation-induced redox processes involving these anions. Scission of the oxidized anions is the main fragmentation pathway for the majority of the practically important anions; (internal) proton transfer involving the aliphatic arms of these anions is a competing reaction. For perfluorinated anions, fluoride loss following dissociative electron attachment to the anion can be even more prominent than this oxidative fragmentation. Bond scission in the anion was also observed for NO{sub 3}{sup -} and B(CN){sub 4}{sup -} anions and indirectly implicated for BF{sub 4}{sup -} and PF{sub 6}{sup -} anions. Among small anions, CF{sub 3}SO{sub 3}{sup -} and N(CN){sub 2}{sup -} are the most stable. Among larger anions, the derivatives of benzoate and imide anions were found to be relatively stable. This stability is due to suppression of the oxidative fragmentation. For benzoates, this is a consequence of the extensive sharing of unpaired electron density by the {pi}-system in the corresponding neutral radical; for the imides, this stability could be the consequence of N-N {sigma}{sup 2}{sigma}*{sup 1} bond formation involving the parent anion. While fragmentation does not occur for these 'exceptional' anions, H atom addition and electron attachment are prominent. Among the typically used

  17. Sugar fragmentation in the maillard reaction cascade: isotope labeling studies on the formation of acetic acid by a hydrolytic beta-dicarbonyl cleavage mechanism.

    PubMed

    Davídek, Tomas; Devaud, Stéphanie; Robert, Fabien; Blank, Imre

    2006-09-06

    The formation of acetic acid was elucidated based on volatile reaction products and related nonvolatile key intermediates. The origin and yield of acetic acid were determined under well-controlled conditions (90-120 degrees C, pH 6-8). Experiments with various 13C-labeled glucose isotopomers in the presence of glycine revealed all six carbon atoms being incorporated into acetic acid: C-1/C-2 ( approximately 70%), C-3/C-4 ( approximately 10%), and C-5/C-6 (approximately 20%). Acetic acid is a good marker of the 2,3-enolization pathway since it is almost exclusively formed from 1-deoxy-2,3-diulose intermediates. Depending on the pH, the acetic acid conversion yield reached 85 mol % when using 1-deoxy-2,3-hexodiulose (1) as a precursor. Hydrolytic beta-dicarbonyl cleavage of 1-deoxy-2,4-hexodiuloses was shown to be the major pathway leading to acetic acid from glucose without the intermediacy of any oxidizing agents. The presence of key intermediates was corroborated for the first time, i.e., tetroses and 2-hydroxy-3-oxobutanal, a tautomer of 1-hydroxy-2,3-butanedione, also referred to as 1-deoxy-2,3-tetrodiulose. The hydrolytic beta-dicarbonyl cleavage represents a general pathway to organic acids, which corresponds to an acyloin cleavage or a retro-Claisen type reaction. Although alternative mechanisms must exist, the frequently reported hydrolytic alpha-dicarbonyl cleavage of 1 can be ruled out as a pathway forming carboxylic acids.

  18. Fission fragment mass distributions in 35Cl+Sm,154144 reactions

    NASA Astrophysics Data System (ADS)

    Tripathi, R.; Sodaye, S.; Sudarshan, K.; Nayak, B. K.; Jhingan, A.; Pujari, P. K.; Mahata, K.; Santra, S.; Saxena, A.; Mirgule, E. T.; Thomas, R. G.

    2015-08-01

    Background: A new type of asymmetric fission was observed in β -delayed fission of 180Tl [Phys. Rev. Lett. 105, 252502 (2010), 10.1103/PhysRevLett.105.252502] as symmetric mass distribution would be expected based on conventional shell effects leading to the formation of N =50 fragments. Following this observation, theoretical calculations were carried out which predict asymmetric mass distribution for several mercury isotopes around mass region of ˜180 at low and moderate excitation energies [Moller, Randrup, and Sierk, Phys. Rev. C 85, 024306 (2012), 10.1103/PhysRevC.85.024306; Andreev, Adamian, and Antonenko, Phys. Rev. C 86, 044315 (2012), 10.1103/PhysRevC.86.044315]. Studies on fission fragment mass distribution are required in this mass region to investigate this newly observed phenomenon. Purpose: The fission fragment mass distributions have been measured in 35Cl+Sm,154144 reactions at Elab=152.5 ,156.1 ,and 163.7 MeV populating compound nuclei in the mass region of ˜180 with variable excitation energy and neutron number to investigate the nature of mass distribution. Method: The fission fragment mass distribution has been obtained by measuring the "time of flight (TOF)" of fragments with respect to the beam pulse using two multiwire proportional counters placed at θlab=±65 .5∘ with respect to the beam direction. From the TOF of fragments, their velocities were determined, which were used to obtain mass distribution taking the compound nucleus as the fissioning system. Results: For both systems, mass distributions, although, appear to be symmetric, could not be fitted well by a single Gaussian. The deviation from a single Gaussian fit is more pronounced for the 35Cl+144Sm reaction. A clear flat top mass distribution has been observed for the 35Cl+144Sm reaction at the lowest beam energy. The mass distribution is very similar to that observed in the 40Ca+142Nd reaction, which populated a similar compound nucleus, but for the pronounced dip in the

  19. Polymerization behavior of Klenow fragment and Taq DNA polymerase in short primer extension reactions.

    PubMed

    Zhao, Guojie; Guan, Yifu

    2010-10-01

    DNA polymerases amplify DNA fragments through primer extension reactions. However, polymerization behavior of short primers in the primer extension process has not been systematically explored. In this study, we examined the minimal primer length required for primer extension, and the effect of primer length, mismatches and other conditions on DNA polymerization using a non-radioactive method. Under the condition we conducted, the shortest primers polymerized by Klenow fragment (KF) and Taq DNA polymerase in our experiments were respectively heptamer and octamer. The extension efficiency was also affected by the up-stream overhanging structure of the primer-template complex. We hypothesized a simple model to interpret these observations based on the polymerase structures. Furthermore, it was found that the longer the primer, the more efficient is the primer extension. These polymerization behavior of short primers lay foundation about DNA polymerization mechanism and development of novel nucleic acid detection assays.

  20. DFT STUDIES OF DP-3 AMYLOSE FRAGMENTS

    USDA-ARS?s Scientific Manuscript database

    This study extends our work on mono- and disaccharides to structures with three glucose residues by two alpha-[1-4] bridges, denoted herein as DP-3's. DFT optimization studies of DP-3 fragments have been carried out at the B3LYP/6-311++G** level of theory. Different hydroxymethyl conformations (gg...

  1. A Population Genetics Study of Anopheles Darlingi (Diptera: Culicidae) from Colombia Based on Random Amplified Polymorphic DNA-Polymerase Chain Reaction and Amplified Fragment Length Polymorphism Markers

    DTIC Science & Technology

    2007-06-01

    0.029; Nm: 8.5; AFLP: FST = 0.05/; Nm: 4.7). According to molecular variance analysis (AMOYA), the genetic distance between populations was...series of population studies were conducted. using mor- phological and molecular tools (Manguin 1999). ori- ented toward clarifying both taxonomic status...and ge- netic structure within its range of distribution. Lounibos and Conn (2000) recently reviewed the use of molecular markers in the study of the

  2. Scleroderma Autoantigens Are Uniquely Fragmented by Metal-catalyzed Oxidation Reactions: Implications for Pathogenesis

    PubMed Central

    Casciola-Rosen, Livia; Wigley, Fredrick; Rosen, Antony

    1997-01-01

    The observation that revelation of immunocryptic epitopes in self antigens may initiate the autoimmune response has prompted the search for processes which induce novel fragmentation of autoantigens as potential initiators of autoimmunity. The reversible ischemia reperfusion which characterizes scleroderma has focused attention on reactive oxygen species as molecules which might induce autoantigen fragmentation. We demonstrate that several of the autoantigens targeted in diffuse scleroderma are uniquely susceptible to cleavage by reactive oxygen species, in a metal-dependent manner. Multiple features of the fragmentation reaction and its inhibition indicate that these autoantigens possess metal-binding sites, which focus metal-catalyzed oxidation reactions (and consequent fragmentation) to specific regions of the antigens. These data suggest that the autoantibody response in scleroderma is the immune marker of unique protein fragmentation, induced by ischemia reperfusion in the presence of appropriate metals, and focus attention on abnormal metal status as a potential pathogenic principle in this disease. PMID:8996243

  3. Conformational studies of cellulosic fragments by DFT

    USDA-ARS?s Scientific Manuscript database

    The study of cellulosic fragments by DFTr is a continuation of our efforts to produce quality structural data that will be valuable to those working in the field of cellulose structure and enzymatic degradation. Using a reduced basis set and density functional DFTr (B3LYP), optimization of cellulosi...

  4. Growth of fullerene fragments using the Diels-Alder cycloaddition reaction: first step towards a C60 synthesis by dimerization.

    PubMed

    Mojica, Martha; Méndez, Francisco; Alonso, Julio A

    2013-02-13

    Density Functional Theory has been used to model the Diels-Alder reactions of the fullerene fragments triindenetriphenilene and pentacyclopentacorannulene with ethylene and 1,3-butadiene. The purpose is to prove the feasibility of using Diels-Alder cycloaddition reactions to grow fullerene fragments step by step, and to dimerize fullerene fragments, as a way to obtain C₆₀. The dienophile character of the fullerene fragments is dominant, and the reaction of butadiene with pentacyclopentacorannulene is favored.

  5. Acid-catalyzed Grob fragmentation reactions of acetonides derived from terpenes.

    PubMed

    Barluenga, José; Alvarez-Pérez, Mónica; Wuerth, Kirsten; Rodríguez, Félix; Fañanás, Francisco J

    2003-03-20

    [reaction: see text] Acetonides derived from different terpenes undergo Grob fragmentation by treatment with a catalytic amount of acid, triflic acid, or boron trifluoride, giving aldehydes containing a cyclopropane or cyclobutane ring with good yields and complete diastereoselectivity. The structure and the stereochemistry of the starting acetonide have a crucial influence on the reaction course.

  6. Fragmentation of 3-hydroxyflavone; a computational and mass spectrometric study.

    PubMed

    Lewars, Errol G; March, Raymond E

    2007-01-01

    In a recent study of the collision-induced dissociation of protonated and deprotonated molecules of 3-, 5-, 6-, 7-, 2'-, 3'- and 4'-hydroxyflavone, it was observed that the ratio, gamma, of the propensities for cross-ring cleavage (CRC) to ring opening (RO) varied by a factor of 660, i.e., from 0.014:1 (for deprotonated 3-hydroxyflavone) to 9.27:1 (for deprotonated 5-hydroxyflavone). An explanation for the variation of gamma was presented in terms of experimental NMR (13)C and (1)H spectra modified by computation. Deprotonated 3-hydroxyflavone exhibited the highest ion signal intensity for fragmentation following RO relative to that for CRC in that gamma = 0.014:1. Because no chemical computations of the fragmentation of protonated and deprotonated monohydroxyflavone molecules have been carried out thus far, the basis on which fragmentation mechanisms for deprotonated 3-hydroxyflavone have been proposed is principally chemical intuition. The energy states of product ions formed in the fragmentation of deprotonated 3-hydroxyflavone molecules were computed by the CBS-4M method implemented in Gaussian 03. The overly demanding calculations needed to handle diradicals reliably and directly were circumvented by a process in which each of the bond-breaking reactions was approximated by a process that gave two monoradicals. Bond energies were calculated, with one exception, from the approximation reactions as the energy of products minus the energy of reactants.

  7. Isotopic resolution of fission fragments from 238U+12C transfer and fusion reactions

    NASA Astrophysics Data System (ADS)

    Caamaño, M.; Rejmund, F.; Derkx, X.; Schmidt, K.-H.; Andouin, L.; Bacri, C.-O.; Barreau, G.; Benlliure, J.; Casarejos, E.; Fernández-Domínguez, B.; Gaudefroy, L.; Golabek, C.; Jurado, B.; Lemasson, A.; Navin, A.; Rejmund, M.; Roger, T.; Shrivastava, A.; Schmitt, C.; Taieb, J.

    2009-10-01

    Recent results from an experiment at GANIL, performed to investigate the main properties of fission-fragment yields and energy distributions in different fissioning nuclei as a function of the excitation energy, in a neutron-rich region of actinides, are presented. Transfer reactions in inverse kinematics between a 238U beam and a 12C target produced different actinides, within a range of excitation energy below 30 MeV. These fissioning nuclei are identified by detecting the target-like recoil, and their kinetic and excitation energy are determined from the reconstruction of the transfer reaction. The large-acceptance spectrometer VAMOS was used to identify the mass, atomic number and charge state of the fission fragments in flight. As a result, the characteristics of the fission-fragment isotopic distributions of a variety of neutron-rich actinides are observed for the first time over the complete range of fission fragments.

  8. Microscopic Calculation of Fission Fragment Energies for the 239Pu(nth,f) Reaction

    SciTech Connect

    Younes, W; Gogny, D

    2011-10-03

    We calculate the total kinetic and excitation energies of fragments produced in the thermal-induced fission of {sup 239}Pu. This result is a proof-of-principle demonstration for a microscopic approach to the calculation of fission-fragment observables for applied data needs. In addition, the calculations highlight the application of a fully quantum mechanical description of scission, and the importance of exploring scission configurations as a function of the moments of the fragments, rather than through global constraints on the moments of the fissioning nucleus. Using a static microscopic calculation of configurations at and near scission, we have identified fission fragments for the {sup 239}Pu (n{sub th}, f) reaction and extracted their total kinetic and excitation energies. Comparison with data shows very good overall agreement between theory and experiment. Beyond their success as a proof of principle, these calculations also highlight the importance of local constraints on the fragments themselves in microscopic calculations.

  9. Space fragment in studies of the Earth

    NASA Technical Reports Server (NTRS)

    Avanesov, G. A.; Ziman, Y. L.

    1982-01-01

    The fragment apparatus, mounted on board the artificial earth satellite Meteor, was created for the operational study of the natural resources of the Earth in the optical range of electromagnetic waves. The orbit of the satellite at an altitude of about 650 km makes it possible to observe the same sectors of the Earth's surface at the same time of day with a periodicity of 15 days.

  10. Simple plate-based, parallel synthesis of disulfide fragments using the CuAAC click reaction.

    PubMed

    Turner, David M; Tom, Christopher T M B; Renslo, Adam R

    2014-12-08

    Disulfide exchange screening is a site-directed approach to fragment-based lead discovery that requires a bespoke library of disulfide-containing fragments. Previously, we described a simple one-pot, two-step synthesis of disulfide fragments from amine- or acid-bearing starting materials. Here, we describe the synthesis of disulfide fragments that bear a 1,4-substituted-1,2,3-triazole linkage between disulfide and molecular diversity element. This work establishes the compatibility of copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) chemistry with a one-pot, two-step reaction sequence that can be readily parallelized. We performed 96 reactions in a single deep-well microtiter plate, employing 48 alkynes and two different azide linker reagents. From this effort, a total of 81 triazole-containing disulfide fragments were obtained in useful isolated yields. Thus, CuAAC chemistry offers an experimentally convenient method to rapidly prepare disulfide fragments that are structurally distinct from fragments accessed via amide, sulfonamide, or isocyanate chemistries.

  11. Nuclear reaction studies

    SciTech Connect

    Alexander, J.M.; Lacey, R.A.

    1994-11-01

    Research focused on the statistical and dynamical properties of ``hot`` nuclei formed in symmetric heavy-ion reactions. Theses included ``flow`` measurements and the mechanism for multifragment disassembly. Model calculations are being performed for the reactions C+C, Ne+Al, Ar+Sc, Kr+Nb, and Xe+La. It is planned to study {sup 40}Ar reactions from 27 to 115 MeV/nucleon. 2 figs., 41 refs.

  12. Interplay between compound and fragments aspects of nuclear fission and heavy-ion reaction

    SciTech Connect

    Moller, Peter; Iwamoto, A; Ichikawa, I

    2010-09-10

    The scission point in nuclear fission plays a special role where one-body system changes to two-body system. Inverse of this situation is realized in heavy-ion fusion reaction where two-body system changes to one body system. Among several peculiar phenomena expected to occur during this change, we focus our attention to the behavior of compound and fragments shell effects. Some aspects of the interplay between compound and fragments shell effect are discussed related to the topics of the fission valleys in the potential energy surface of actinide nuclei and the fusion-like trajectory found in the cold fusion reaction leading to superheavy nuclei.

  13. Mutagenicity Assessment of Organophosphates using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism Assay

    PubMed Central

    Bhinder, Preety; Chaudhry, Asha

    2013-01-01

    Objectives: In this study we have evaluated the mutagenicity of organophosphate pesticides acephate, chlorpyrifos, and profenofos using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay with the mosquito Culex quinquefasciatus taken as an experimental model. Materials and Methods: Second instar larvae were treated with LC20 of each pesticide for 24 h and mutations induced in the sequence of mitochondrial COII gene (690bp) were studied from restriction patterns generated with AluI, PacI, and PsiI restriction endonucleases. Results: Variations in the number and size of digested fragments were recorded from treated individuals compared with controls showing that the restriction enzymes created a cut at different locations. In addition, sequences of COII gene from control and treated individuals were also used to confirm the RFLP patterns. From the sequence alignment data, it was found that mutations caused the destruction and generation of restriction sites in the gene sequence of treated individuals. Conclusion: This study indicates that all the three pesticides had potential to induce mutations in the normal sequence of COII gene and also advocates the use of PCR-RFLP assay as an efficient, rapid, and sensitive technique to detect mutagenicity of pesticides. PMID:24403735

  14. Construction of an antimyoglobin single-chain variable fragment with rapid reaction kinetics.

    PubMed

    Jang, Jun-Hyuck; Kim, Dong-Hyung; Paek, Se-Hwan; Woo, Eui-Jeon; Kim, Young-Wan

    2016-01-01

    Antibodies with rapid reaction kinetics (high association and dissociation rates), named reversible antibodies, are used to perform continuous monitoring of sensitive disease biomarkers. In cases of acute myocardial infarction (AMI), continuous monitoring and early diagnosis are important. Human myoglobin (Myo) is a useful biomarker for AMI during the early stage after the onset of symptoms. In this study, a single-chain variable fragment (scFv) specific to Myo was derived from an IgG antibody that has rapid reaction kinetics. Enzyme-linked immunosorbent assay revealed that recombinant scFv exhibited 3.8-fold reduced affinity compared with the parent IgG antibody based on the antibody concentration necessary for 50% of the maximum signal. The scFv retained the rapid reaction kinetic mode with average kon and koff of 2.63 × 10(5) M(-1) Sec(-1) and 3.25 × 10(-3) Sec(-1) , respectively, which were reduced to 10- and 2.3-fold compared with those of the parent antibody. The equilibrium constant for the association of the scFv (KA = 8.09 × 10(7) M(-1) ) was 4.6-fold lower than that of its parent IgG antibody. This scFv may be a starting point for further mutagenesis/kinetic and structural analyses providing valuable insight into the mechanism of reversible antibodies.

  15. Exothermic Surface Reactions in Alumina-Aluminum Shell-Core Nanoparticles with Iodine Oxide Decomposition Fragments

    DTIC Science & Technology

    2014-02-22

    AND SUBTITLE Sa. CONTRACT NUMBER Exothennic smface reactions in alumina-aluminum shell-core W911NF-11-1-0439 nanoprui icles with iodine oxide...is observed for aluminum and an iodine -containing oxidizer. This PIR is exothermic and precedes the main exothennic reaction conesponding to aluminum...combustion. For the aluminum and iodine oxide system, exothennic smface chemistiy was recently predicted for I-0 fragments fonning bridge bonds with

  16. Nuclear fragmentation and charge-exchange reactions induced by pions in the Δ -resonance region

    NASA Astrophysics Data System (ADS)

    Feng, Zhao-Qing

    2016-11-01

    The dynamics of the nuclear fragmentations and the charge exchange reactions in pion-nucleus collisions near the Δ (1232) resonance energies has been investigated within the Lanzhou quantum molecular dynamics transport model. An isospin-, momentum-, and density-dependent pion-nucleon potential is implemented in the model, which influences the pion dynamics, in particular the kinetic energy spectra, but weakly impacts the fragmentation mechanism. The absorption process in pion-nucleon collisions to form the Δ (1232) resonance dominates the heating mechanism of the target nucleus. The excitation energy transferred to the target nucleus increases with the pion kinetic energy and is similar for both π-- and π+-induced reactions. The magnitude of fragmentation of the target nucleus weakly depends on the pion energy. The isospin ratio in the pion double-charge exchange is influenced by the isospin ingredient of target nucleus.

  17. The Conversion of Smaller Borane Fragments to Larger Structures. Systematics of Boron Hydride Reactions.

    DTIC Science & Technology

    1984-12-31

    Robert W. Parry and Goji Kodama Contract DAAG-29-8rl-K-Ol0l S. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK S Department of...Entered; THE CONVERSION OF SMALLER BORANE FRAGMENTS TO LARGER STRUCTURES - SYSTEMATICS OF BORON HYDRIDE REACTIONS FINAL REPORT ROBERT W. PARRY AND GOJI

  18. Purification and characterization of Fab fragments with rapid reaction kinetics against myoglobin.

    PubMed

    Song, Hyung-Nam; Kim, Dong-Hyung; Park, Sung-Goo; Lee, Myung Kyu; Paek, Se-Hwan; Woo, Eui-Jeon

    2015-01-01

    Myoglobin is an early biomarker for acute myocardial infarction. Recently, we isolated the antibody IgG-Myo2-7ds, which exhibits unique rapid reaction kinetics toward human myoglobin antigen. Antibodies with rapid dissociation kinetics are thought to be premature IgG forms that are produced during the early stage of in vivo immunization. In the present study, we identified the epitope region of the IgG-Myo2-7ds antibody to be the C-terminal region of myoglobin, which corresponds to 144-154 aa. The Fab fragment was directly purified by papain cleavage and protein G affinity chromatography and demonstrated kinetics of an association constant of 4.02 × 10(4) M(-1) s(-1) and a dissociation constant of 2.28 × 10(-2) s(-1), which retained the unique reaction kinetics of intact IgG-Myo2-7ds antibodies. Because a rapid dissociation antibody can be utilized for antibody recycling, the results from this study would provide a platform for the development of antibody engineering in potential diagnostic areas such as a continuous monitoring system for heart disease.

  19. Influence of fragment reaction of relativistic heavy charged particles on heavy-ion radiotherapy

    NASA Astrophysics Data System (ADS)

    Matsufuji, Naruhiro; Fukumura, Akifumi; Komori, Masataka; Kanai, Tatsuaki; Kohno, Toshiyuki

    2003-06-01

    The production of projectile fragments is one of the most important, but not yet perfectly understood, problems to be considered when planning for the utilization of high-energy heavy charged particles for radiotherapy. This paper reports our investigation of the fragments' fluence and linear energy transfer (LET) spectra produced from various incident ions using an experimental approach to reveal these physical qualities of the beams. Polymethyl methacrylate, as a substitute for the human body, was used as a target. A ΔE-E counter telescope with a plastic scintillator and a BGO scintillator made it possible to identify the species of fragments based on differences of various elements. By combining a gas-flow proportional counter with a counter telescope system, LET spectra as well as fluence spectra of the fragments were derived for each element down from the primary particles to hydrogen. Among them, the information on hydrogen and helium fragments was derived for the first time. The result revealed that the number of light fragments, such as hydrogen and helium, became larger than the number of primaries in the vicinity of the range end. However, the greater part of the dose delivered to a cell was still governed by the primaries. The calculated result of a simulation used for heavy-ion radiotherapy indicated room for improving the reaction model.

  20. Carbon fragmentation measurements and validation of the Geant4 nuclear reaction models for hadrontherapy.

    PubMed

    De Napoli, M; Agodi, C; Battistoni, G; Blancato, A A; Cirrone, G A P; Cuttone, G; Giacoppo, F; Morone, M C; Nicolosi, D; Pandola, L; Patera, V; Raciti, G; Rapisarda, E; Romano, F; Sardina, D; Sarti, A; Sciubba, A; Scuderi, V; Sfienti, C; Tropea, S

    2012-11-21

    Nuclear fragmentation measurements are necessary when using heavy-ion beams in hadrontherapy to predict the effects of the ion nuclear interactions within the human body. Moreover, they are also fundamental to validate and improve the Monte Carlo codes for their use in planning tumor treatments. Nowadays, a very limited set of carbon fragmentation cross sections are being measured, and in particular, to our knowledge, no double-differential fragmentation cross sections at intermediate energies are available in the literature. In this work, we have measured the double-differential cross sections and the angular distributions of the secondary fragments produced in the (12)C fragmentation at 62 A MeV on a thin carbon target. The experimental data have been used to benchmark the prediction capability of the Geant4 Monte Carlo code at intermediate energies, where it was never tested before. In particular, we have compared the experimental data with the predictions of two Geant4 nuclear reaction models: the Binary Light Ions Cascade and the Quantum Molecular Dynamic. From the comparison, it has been observed that the Binary Light Ions Cascade approximates the angular distributions of the fragment production cross sections better than the Quantum Molecular Dynamic model. However, the discrepancies observed between the experimental data and the Monte Carlo simulations lead to the conclusion that the prediction capability of both models needs to be improved at intermediate energies.

  1. Carbon fragmentation measurements and validation of the Geant4 nuclear reaction models for hadrontherapy

    NASA Astrophysics Data System (ADS)

    De Napoli, M.; Agodi, C.; Battistoni, G.; Blancato, A. A.; Cirrone, G. A. P.; Cuttone, G.; Giacoppo, F.; Morone, M. C.; Nicolosi, D.; Pandola, L.; Patera, V.; Raciti, G.; Rapisarda, E.; Romano, F.; Sardina, D.; Sarti, A.; Sciubba, A.; Scuderi, V.; Sfienti, C.; Tropea, S.

    2012-11-01

    Nuclear fragmentation measurements are necessary when using heavy-ion beams in hadrontherapy to predict the effects of the ion nuclear interactions within the human body. Moreover, they are also fundamental to validate and improve the Monte Carlo codes for their use in planning tumor treatments. Nowadays, a very limited set of carbon fragmentation cross sections are being measured, and in particular, to our knowledge, no double-differential fragmentation cross sections at intermediate energies are available in the literature. In this work, we have measured the double-differential cross sections and the angular distributions of the secondary fragments produced in the 12C fragmentation at 62 A MeV on a thin carbon target. The experimental data have been used to benchmark the prediction capability of the Geant4 Monte Carlo code at intermediate energies, where it was never tested before. In particular, we have compared the experimental data with the predictions of two Geant4 nuclear reaction models: the Binary Light Ions Cascade and the Quantum Molecular Dynamic. From the comparison, it has been observed that the Binary Light Ions Cascade approximates the angular distributions of the fragment production cross sections better than the Quantum Molecular Dynamic model. However, the discrepancies observed between the experimental data and the Monte Carlo simulations lead to the conclusion that the prediction capability of both models needs to be improved at intermediate energies.

  2. Fission-fragment mass yields of highly excited nuclei with 119 ≤ A ≤ 218 produced in various reactions

    NASA Astrophysics Data System (ADS)

    Denisov, V. Yu.; Sedykh, I. Yu.

    2017-07-01

    The characteristics of fission fragments of various highly-excited nuclei with 119 ≤ A ≤ 218, which are formed by γ- and α-captures, and by fusion-fission reactions, are discussed in details. The yields of fission fragments of these nuclei are related to the number of states of the two-fragment systems at the two-body saddle points. The various experimental distributions of fission fragments are well described in the model.

  3. Low energy electron induced fragmentation and reactions of DNA and its molecular components

    NASA Astrophysics Data System (ADS)

    Bass, Andrew

    2005-05-01

    Much research has been stimulated by the recognition that ionizing radiation can, in condensed matter, generate large numbers of secondary electrons with energies less than 20 eV [1] and by the experimental demonstration that such electrons may induce both single and double strand breaks in plasmid DNA [2]. Identifying the underlying mechanisms involves several research methodologies, from further experiments with DNA to studies of the electron interaction with the component `sub-units' of DNA in both the gas and condensed phases [3]. In particular, understanding electron-induced strand break damage, the type of damage most difficult for organisms to repair, necessitates study of the sub-units of DNA back-bone, and here Tetrahyrofuran (THF) and its derivatives, provide a useful model for the furyl ring at the centre of the deoxyribose sugar. In this contribution, we review with particular reference to DNA and related molecules, the use of electron spectroscopy and mass spectrometry to study electron-induced fragmentation and reactions in thin molecular solids. We describe a newly completed instrument that combines laser post-ionization with a time-of-flight mass analyzer for highly sensitive ion and neutral detection. Use of the instrument is illustrated with results for THF and derivatives. Anion desorption measurements reveal the role of transient negative ions (TNI) and Dissociative Electron Attachment in significant molecular fragmentation and permit effective cross sections for this electron-induced damage to be obtained. The neutral yield functions also illustrate the importance of TNI, mirroring features seen in recently measured cross sections for electron induced aldehyde production in THF [4]. 1. J. A. Laverne and S. M. Pimblott, Radiat. Res. 141, 208 (1995) 2. B. Boudaiffa, et al, Science 287, 1658 (2000) 3. L. Sanche. Physica Scripta. 68, C108, (2003) 4. S.-P. Breton, et al.,J. Chem. Phys. 121, 11240 (2004)

  4. The Family Circle: A Study in Fragmentation

    ERIC Educational Resources Information Center

    Bronfenbrenner, Urie

    1976-01-01

    Presents data describing the fragmentation of the family, suggests causes for the fragmentation, and offers suggestions for reversing the trend. The suggestions focus on day care, part-time employment practices, enhancing the position of women, and work and responsibility. (IRT)

  5. Study of fragmentation at low excitation energies within a dynamical microscopic theory

    SciTech Connect

    Dhawan, Jatinder K.; Puri, Rajeev K.

    2007-05-15

    We present the theoretical study of fragmentation at low excitation energies within dynamical microscopic theory namely, simulated annealing clusterization algorithm (SACA) and quantum molecular dynamics (QMD) model. For low excitation energy reactions, we choose the balance energies for a large number of reactions throughout the periodic table. We see that SACA gives multiplicities in terms of power law. For light fragments, it is close to 1/3, whereas, for heavier fragments it is nearly mass independent suggesting their origin in terms of participant-spectator picture.

  6. Mass spectrometry of oligosaccharides by chloride-attachment reactions: the origin of fragment loss.

    PubMed

    Promé, D; Promé, J C; Puzo, G; Aurelle, H

    1985-07-01

    The direct exposure, negative chemical ionisation, chloride-attachment mass spectrometry of trehalose and sucrose gave abundant chloride-attached molecular ions. The same feature was observed when these sugars were subjected to fast-atom bombardment (f.a.b.) in a glycerol matrix containing ammonium chloride. No characteristic fragment ion was found when trehalose was analysed by either method. In contrast, sucrose gave intense chloride-containing fragments, arising by glycosidic cleavage, when analysed by the first method, whereas such cleavage was not detectable by f.a.b.-ammonium chloride analysis. However, the mass-analysed ion kinetic energy (m.i.k.e.) spectra of the (M + Cl)- ions from either trehalose and sucrose, generated under f.a.b.-ammonium chloride conditions, showed glycosidic cleavage reactions in addition to a large loss of HCl. These cleavage reactions might be attributed to SN2-like reactions on the acetal carbon atom and to base-induced eliminations, and they were enhanced by collision-induced dissociations. However, the relative abundance of such glycosidic cleavages from the ionic state would be too weak to explain the presence of the large chloride-containing fragments in the direct exposure spectra of sucrose. Thus, these ions were mainly produced by a thermal cleavage followed by chloride-attachment reactions.

  7. Experimental studies of quasi-fission reactions

    SciTech Connect

    Back, B.B.

    1988-01-01

    A large number of recent experimental studies have shown that a substantial fraction of the total reaction cross section in heavy-ion reactions is found in fission-like processes, which do not result from the fission decay of a completely fused system. Following the suggestion of Swiatecki such processes, which represents a complete relaxation of the relative kinetic energy and a substantial amount of net mass transfer between the two fragments, are denoted quasi-fission reactions. They are distinct from compound fission reactions by bypassing the stage of a completely fused-system. This typically means that they are associated with short reaction times, which results in several measurable characteristics such as broken forward-backward symmetries, large anisotropies of the angular distributions and increased widths of the fragment mass distributions. The distinction between quasi-fission and deep inelastic reactions is less stringent and has the character of a gradual evolution from one reaction type to the other, as found also as quasi-elastic reaction evolves into deeply inelastic processes as a function of the total kinetic energy loss. In the present paper some of the experimental data characterizing quasi-fission reactions are reviewed and discussed. 22 refs., 6 figs.

  8. Tungsten fragmentation in nuclear reactions induced by high-energy cosmic-ray protons

    SciTech Connect

    Chechenin, N. G. Chuvilskaya, T. V.; Shirokova, A. A.; Kadmenskii, A. G.

    2015-01-15

    Tungsten fragmentation arising in nuclear reactions induced by cosmic-ray protons in space-vehicle electronics is considered. In modern technologies of integrated circuits featuring a three-dimensional layered architecture, tungsten is frequently used as a material for interlayer conducting connections. Within the preequilibrium model, tungsten-fragmentation features, including the cross sections for the elastic and inelastic scattering of protons of energy between 30 and 240 MeV; the yields of isotopes and isobars; their energy, charge, and mass distributions; and recoil energy spectra, are calculated on the basis of the TALYS and EMPIRE-II-19 codes. It is shown that tungsten fragmentation affects substantially forecasts of failures of space-vehicle electronics.

  9. Ontology aided modeling of organic reaction mechanisms with flexible and fragment based XML markup procedures.

    PubMed

    Sankar, Punnaivanam; Aghila, Gnanasekaran

    2007-01-01

    The mechanism models for primary organic reactions encoding the structural fragments undergoing substitution, addition, elimination, and rearrangements are developed. In the proposed models, each and every structural component of mechanistic pathways is represented with flexible and fragment based markup technique in XML syntax. A significant feature of the system is the encoding of the electron movements along with the other components like charges, partial charges, half bonded species, lone pair electrons, free radicals, reaction arrows, etc. needed for a complete representation of reaction mechanism. The rendering of reaction schemes described with the proposed methodology is achieved with a concise XML extension language interoperating with the structure markup. The reaction scheme is visualized as 2D graphics in a browser by converting them into SVG documents enabling the desired layouts normally perceived by the chemists conventionally. An automatic representation of the complex patterns of the reaction mechanism is achieved by reusing the knowledge in chemical ontologies and developing artificial intelligence components in terms of axioms.

  10. Projectile-breakup-induced fission-fragment angular distributions in the 6Li+232Th reaction

    NASA Astrophysics Data System (ADS)

    Pal, A.; Santra, S.; Chattopadhyay, D.; Kundu, A.; Ramachandran, K.; Tripathi, R.; Roy, B. J.; Nag, T. N.; Sawant, Y.; Sarkar, D.; Nayak, B. K.; Saxena, A.; Kailas, S.

    2017-08-01

    Background: Experimental anisotropy in fission-fragment (FF) angular distribution in reactions involving weakly bound stable projectiles with actinide targets are enhanced compared to statistical saddle-point model (SSPM) predictions. Contributions from breakup- or transfer-induced fission to total fission are cited as possible reasons for such enhancement. Purpose: To identify the breakup- or transfer-induced fission channels in 6Li+232Th reaction and to investigate their effects on FF angular anisotropy. Methods: The FF angular distributions have been measured exclusively at three beam energies (28, 32, and 36 MeV) around the Coulomb barrier in coincidence with projectile breakup fragments like α , d , and p using Si strip detectors. The angular anisotropy obtained for different exclusive breakup- or transfer-induced fission channels are compared with that for total fission. SSPM and pre-equilibrium fission models have been employed to obtain theoretical FF angular anisotropy. Results: Angular anisotropy of the fission fragments produced by different transfer- or breakup-induced fission reactions have been obtained separately in the rest frame of respective recoiling nuclei. Some of these anisotropies were found to be stronger than those of the inclusive fission. Overall angular distributions of transfer or breakup fission, integrated over all possible recoil angles with weight factor proportional to differential cross section of the complementary breakup fragment emitted in coincidence in all possible directions, were obtained. It was observed that the overall FF angular anisotropy for each of these fission channels is less than or equal to the anisotropy of total fission at all the measured energies. Assuming isotropic out-of-plane correlations between the fission fragments and light-charged particles, the overall breakup- or transfer-induced fission fragment angular distributions do not explain the observed enhancement in FF anisotropy of total fission. Pre

  11. Selective control over fragmentation reactions in polyatomic molecules using impulsive laser alignment.

    PubMed

    Xie, Xinhua; Doblhoff-Dier, Katharina; Xu, Huailiang; Roither, Stefan; Schöffler, Markus S; Kartashov, Daniil; Erattupuzha, Sonia; Rathje, Tim; Paulus, Gerhard G; Yamanouchi, Kaoru; Baltuška, Andrius; Gräfe, Stefanie; Kitzler, Markus

    2014-04-25

    We investigate the possibility of using molecular alignment for controlling the relative probability of individual reaction pathways in polyatomic molecules initiated by electronic processes on the few-femtosecond time scale. Using acetylene as an example, it is shown that aligning the molecular axis with respect to the polarization direction of the ionizing laser pulse does not only allow us to enhance or suppress the overall fragmentation yield of a certain fragmentation channel but, more importantly, to determine the relative probability of individual reaction pathways starting from the same parent molecular ion. We show that the achieved control over dissociation or isomerization pathways along specific nuclear degrees of freedom is based on a controlled population of associated excited dissociative electronic states in the molecular ion due to relatively enhanced ionization contributions from inner valence orbitals.

  12. Measurements of charge distributions of the fragments in the low energy fission reaction

    NASA Astrophysics Data System (ADS)

    Wang, Taofeng; Han, Hongyin; Meng, Qinghua; Wang, Liming; Zhu, Liping; Xia, Haihong

    2013-01-01

    The measurement for charge distributions of fragments in spontaneous fission 252Cf has been performed by using a unique style of detector setup consisting of a typical grid ionization chamber and a ΔΕ-Ε particle telescope, in which a thin grid ionization chamber served as the ΔΕ-section and the E-section was an Au-Si surface barrier detector. The typical physical quantities of fragments, such as mass number and kinetic energies as well as the deposition in the gas ΔΕ detector and E detector were derived from the coincident measurement data. The charge distributions of the light fragments for the fixed mass number A2* and total kinetic energy (TKE) were obtained by the least-squares fits for the response functions of the ΔΕ detector with multi-Gaussian functions representing the different elements. The results of the charge distributions for some typical fragments are shown in this article which indicates that this detection setup has the charge distribution capability of Ζ:ΔΖ>40:1. The experimental method developed in this work for determining the charge distributions of fragments is expected to be employed in the neutron induced fissions of 232Th and 238U or other low energy fission reactions.

  13. Fission fragment mass distributions in reactions forming the {sup 213}Fr compound nucleus

    SciTech Connect

    Appannababu, S.; Mukherjee, S.; Deshmukh, N. N.; Rath, P. K.; Singh, N. L.; Nayak, B. K.; Thomas, R. G.; Choudhury, R. K.; Sugathan, P.; Jhingan, A.; Negi, D.; Prasad, E.

    2011-03-15

    The fission fragment mass angle correlations and mass ratio distributions have been investigated for the two systems {sup 16}O+{sup 197}Au and {sup 27}Al+{sup 186}W, leading to the same compound nucleus {sup 213}Fr around the Coulomb barrier energies. Systematic analysis of the variance of the mass distributions as a function of temperature and angular momentum suggests true compound nuclear fission for both the reactions, indicating the absence of nonequilibrium fission processes.

  14. Isotopic effects of fragment-yields in proton induced reactions on Sn isotopes

    NASA Astrophysics Data System (ADS)

    Balabekyan, A. R.; Danagulyan, A. S.; Drnoyan, J. R.; Demekhina, N. A.; Adam, J.; Kalinnikov, V. G.; Musulmanbekov, G.

    2004-04-01

    Analysis of isotopic characteristics of products related to the inclusive data measured using activation method in proton reactions at the energies 0.66, 1.0 and 8.1 GeV with separated tin isotopes is presented. Experimental results are systematized in form of cross section ratios for two targets of different isotope composition. Scaling behavior is observed for reactions with heavy residuals in the same manner as in light fragment production processes. These results are discussed in the light of relevant recent data. Finally, dependence of scaling parameters on the target neutron excess is observed.

  15. Study of leading hadrons in gluon and quark fragmentation

    NASA Astrophysics Data System (ADS)

    Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G. J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Berntzon, L.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Buschbeck, B.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crennell, D.; Cuevas, J.; D'Hondt, J.; Dalmau, J.; da Silva, T.; da Silva, W.; Della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Herr, H.; Hoffman, J.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Jackson, J. N.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Johansson, P. D.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kersevan, B. P.; Kerzel, U.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nicolaidou, R.; Nikolenko, M.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Rames, J.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Taffard, A. C.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.-L.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zhuravlov, V.; Zimin, N. I.; Zintchenko, A.; Zupan, M.; Delphi Collaboration

    2006-12-01

    The study of quark jets in e+e- reactions at LEP has demonstrated that the hadronisation process is reproduced well by the Lund string model. However, our understanding of gluon fragmentation is less complete. In this study enriched quark and gluon jet samples of different purities are selected in three-jet events from hadronic decays of the Z collected by the DELPHI experiment in the LEP runs during 1994 and 1995. The leading systems of the two kinds of jets are defined by requiring a rapidity gap and their sum of charges is studied. An excess of leading systems with total charge zero is found for gluon jets in all cases, when compared to Monte Carlo simulations with JETSET (with and without Bose-Einstein correlations included) and ARIADNE. The corresponding leading systems of quark jets do not exhibit such an excess. The influence of the gap size and of the gluon purity on the effect is studied and a concentration of the excess of neutral leading systems at low invariant masses (≲ 2 GeV /c2) is observed, indicating that gluon jets might have an additional hitherto undetected fragmentation mode via a two-gluon system. This could be an indication of a possible production of gluonic states as predicted by QCD.

  16. Study of leading hadrons in gluon and quark fragmentation

    NASA Astrophysics Data System (ADS)

    DELPHI Collaboration; Abdallah, J.; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, J. E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G. J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Berntzon, L.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Buschbeck, B.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crennell, D.; Cuevas, J.; D'Hondt, J.; Dalmau, J.; da Silva, T.; da Silva, W.; Della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Herr, H.; Hoffman, J.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Jackson, J. N.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Johansson, P. D.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kersevan, B. P.; Kerzel, U.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Mc Nulty, R.; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nicolaidou, R.; Nikolenko, M.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Rames, J.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Sekulin, R.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Taffard, A. C.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.-L.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zhuravlov, V.; Zimin, N. I.; Zintchenko, A.; Zupan, M.

    2006-12-01

    The study of quark jets in ee reactions at LEP has demonstrated that the hadronisation process is reproduced well by the Lund string model. However, our understanding of gluon fragmentation is less complete. In this study enriched quark and gluon jet samples of different purities are selected in three-jet events from hadronic decays of the Z collected by the DELPHI experiment in the LEP runs during 1994 and 1995. The leading systems of the two kinds of jets are defined by requiring a rapidity gap and their sum of charges is studied. An excess of leading systems with total charge zero is found for gluon jets in all cases, when compared to Monte Carlo simulations with JETSET (with and without Bose Einstein correlations included) and ARIADNE. The corresponding leading systems of quark jets do not exhibit such an excess. The influence of the gap size and of the gluon purity on the effect is studied and a concentration of the excess of neutral leading systems at low invariant masses (≲2 GeV/c) is observed, indicating that gluon jets might have an additional hitherto undetected fragmentation mode via a two-gluon system. This could be an indication of a possible production of gluonic states as predicted by QCD.

  17. Studies on the HLA-DRB1 genotypes in Japanese women with severe pre-eclampsia positive and negative for anticardiolipin antibody using a polymerase chain reaction-restriction fragment length polymorphism method.

    PubMed

    Takakuwa, K; Honda, K; Ishii, K; Hataya, I; Yasuda, M; Tanaka, K

    1999-12-01

    The human leukocyte antigen (HLA)-DR genotype was determined in 54 Japanese women with severe pre-eclampsia in order to elucidate the relationship between HLA-DR antigen systems and pre-eclampsia. The patients were divided into two groups according to positivity for the anticardiolipin antibody (ACA), i.e. one patient group negative for ACA (n = 41) and the other patient group positive for ACA (n = 13). The frequency of each HLA-DRB1 allele in both groups was compared with that in 81 normally fertile Japanese women who had not experienced pre-eclampsia. The genotypes of HLA-DR antigens were determined using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The frequency of DRB1*04 and DRB1*0403 in the patient group positive for the ACA was significantly higher compared with that in the group of normal fertile women (P< 0.05). The frequency of each HLA-DRB1 allele was not significantly different between patient group with pre-eclampsia negative for ACA and group of normal fertile women. These results suggest a difference in the immunogenetic background between the patient groups with severe pre-eclampsia positive and negative for the ACA.

  18. Global transformation and fate of SOA: Implications of low-volatility SOA and gas-phase fragmentation reactions

    NASA Astrophysics Data System (ADS)

    Shrivastava, Manish; Easter, Richard C.; Liu, Xiaohong; Zelenyuk, Alla; Singh, Balwinder; Zhang, Kai; Ma, Po-Lun; Chand, Duli; Ghan, Steven; Jimenez, Jose L.; Zhang, Qi; Fast, Jerome; Rasch, Philip J.; Tiitta, Petri

    2015-05-01

    Secondary organic aerosols (SOA) are large contributors to fine-particle loadings and radiative forcing but are often represented crudely in global models. We have implemented three new detailed SOA treatments within the Community Atmosphere Model version 5 (CAM5) that allow us to compare the semivolatile versus nonvolatile SOA treatments (based on some of the latest experimental findings) and to investigate the effects of gas-phase fragmentation reactions. The new treatments also track SOA from biomass burning and biofuel, fossil fuel, and biogenic sources. For semivolatile SOA treatments, fragmentation reactions decrease the simulated annual global SOA burden from 7.5 Tg to 1.8 Tg. For the nonvolatile SOA treatment with fragmentation, the burden is 3.1 Tg. Larger differences between nonvolatile and semivolatile SOA (up to a factor of 5) exist in areas of continental outflow over the oceans. According to comparisons with observations from global surface Aerosol Mass Spectrometer measurements and the U.S. Interagency Monitoring of Protected Visual Environments (IMPROVE) network measurements, the FragNVSOA treatment, which treats SOA as nonvolatile and includes gas-phase fragmentation reactions, agrees best at rural locations. Urban SOA is underpredicted, but this may be due to the coarse model resolution. All three revised treatments show much better agreement with aircraft measurements of organic aerosols (OA) over the North American Arctic and sub-Arctic in spring and summer, compared to the standard CAM5 formulation. This is mainly due to the oxidation of SOA precursor gases from biomass burning, not included in standard CAM5, and long-range transport of biomass burning OA at high altitudes. The revised model configurations that include fragmentation (both semivolatile and nonvolatile SOA) show much better agreement with MODerate resolution Imaging Spectrometers (MODIS) aerosol optical depth data over regions dominated by biomass burning during the summer

  19. Knockout and fragmentation reactions using a broad range of tin isotopes

    NASA Astrophysics Data System (ADS)

    Rodríguez-Sánchez, J. L.; Benlliure, J.; Bertulani, C. A.; Vargas, J.; Ayyad, Y.; Alvarez-Pol, H.; Atkinson, J.; Aumann, T.; Beceiro-Novo, S.; Boretzky, K.; Caamaño, M.; Casarejos, E.; Cortina-Gil, D.; Díaz-Cortes, J.; Fernández, P. Díaz; Estrade, A.; Geissel, H.; Kelić-Heil, A.; Litvinov, Yu. A.; Mostazo, M.; Paradela, C.; Pérez-Loureiro, D.; Pietri, S.; Prochazka, A.; Takechi, M.; Weick, H.; Winfield, J. S.

    2017-09-01

    Production cross sections of residual nuclei obtained by knockout and fragmentation reactions of different tin isotopes accelerated at 1 A GeV have been measured with the fragment separator (FRS) at GSI, Darmstadt. The new measurements are used to investigate the neutron-excess dependence of the neutron- and proton-knockout cross sections. These cross sections are compared to Glauber model calculations coupled to a nuclear de-excitation code in order to investigate the role of the remnant excitations. This bench marking shows an overestimation of the cross sections for the removal of deeply bound nucleons. A phenomenological increase in the excitation energy induced in the remnants produced in these cases allows us to reproduce the measured cross sections.

  20. Orbital deflection of fragments produced through peripheral reactions of heavy nuclei at 290 MeV/nucleon

    NASA Astrophysics Data System (ADS)

    Momota, S.; Kanazawa, M.; Kitagawa, A.; Sato, S.

    2017-02-01

    The orbital deflection phenomenon of reaction products formed through peripheral reactions of heavy nuclei at intermediate energy is studied to examine the contributions of the Coulomb potential and nuclear potential that act between the projectile and target nuclei. The angular distributions of fragments produced in 1-nucleon removal and exchange reactions of 40Ar and 84Kr beams with C, Al, Nb, Tb, and Au targets at 290 MeV/nucleon were observed. A significant deflection effect was successfully identified in observed angular distributions at energies as low as Ei = 100 MeV/nucleon. The deflection effect increases with the atomic number of the target nuclei. The observed deflection effect is consistently explainable using the classical deflection angle, which is obtained with respect to a simple framework of the Coulomb potential and the real part of the energy-dependent nuclear potential, and the characteristic impact parameter between the projectile and target nuclei.

  1. Microfluidic device for integrated restriction digestion reaction and resulting DNA fragment analysis.

    PubMed

    Xie, Hua; Li, Bowei; Zhong, Runtao; Qin, Jianhua; Zhu, Yisheng; Lin, Bingcheng

    2008-12-01

    A microfluidic system combining temperature-controlled reactor, analyte delivery, chip electrophoresis (CE) separation, and fluorescence detection was developed, in which the heaters, resistance temperature detectors, enzymatic reactors, CE channels, and pneumatic valves/pumps were integrated onto a single glass-PDMS chip. The microdevice was used to perform the digestion reaction, followed by on-line electrophoresis separation and detection of the resulting fragments with endonuclease BamHI and FokI as models. Pneumatic valves/pumps served not only for isolating the reaction region from the separation medium to prevent contamination, but also for delivering and quantitatively diluting the fluid from the reaction chamber to the CE section. Thus enzymatic reaction and electrophoresis separation could be insulated and connected as needed. A dynamic coating procedure with the use of PVP and mannitol was firstly adopted for glass-PDMS hybrid chip-based DNA separations, leading to an improved separation efficiency with reproducible migration time and theoretical plates. The expected 263- and 287-bp digestion products of BamHI and FokI were definitely verified by the size-based electrophoretic separation and detection. The whole integrated reaction-CE system can be manipulated in a simple manner with good reproducibility, which is expected to be applied in other on-line analysis of various biochemical reactions.

  2. Substituent effects on the gas-phase fragmentation reactions of sulfonium ion containing peptides.

    PubMed

    Sierakowski, James; Amunugama, Mahasilu; Roberts, Kade D; Reid, Gavin E

    2007-01-01

    The multistage mass spectrometric (MS/MS and MS3) gas-phase fragmentation reactions of methionine side-chain sulfonium ion containing peptides formed by reaction with a series of para-substituted phenacyl bromide (XBr where X=CH2COC6H4R, and R=--COOH, --COOCH3, --H, --CH3 and --CH2CH3) alkylating reagents have been examined in a linear quadrupole ion trap mass spectrometer. MS/MS of the singly (M+) and multiply ([M++nH](n+1)+) charged precursor ions results in exclusive dissociation at the fixed charge containing side chain, independently of the amino acid composition and precursor ion charge state (i.e., proton mobility). However, loss of the methylphenacyl sulfide side-chain fragment as a neutral versus charged (protonated) species was observed to be highly dependent on the proton mobility of the precursor ion, and the identity of the phenacyl group para-substituent. Molecular orbital calculations were performed at the B3LYP/6-31+G** level of theory to calculate the theoretical proton affinities of the neutral side-chain fragments. The log of the ratio of neutral versus protonated side-chain fragment losses from the derivatized side chain were found to exhibit a linear dependence on the proton affinity of the side-chain fragmentation product, as well as the proton affinities of the peptide product ions. Finally, MS3 dissociation of the nominally identical neutral and protonated loss product ions formed by MS/MS of the [M++H]2+ and [M++2H]3+ precursor ions, respectively, from the peptide GAILM(X)GAILK revealed significant differences in the abundances of the resultant product ions. These results suggest that the protonated peptide product ions formed by gas-phase fragmentation of sulfonium ion containing precursors in an ion trap mass spectrometer do not necessarily undergo intramolecular proton 'scrambling' prior to their further dissociation, in contrast to that previously demonstrated for peptide ions introduced by external ionization sources.

  3. Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the 18O + 232Th reaction

    NASA Astrophysics Data System (ADS)

    Léguillon, R.; Nishio, K.; Hirose, K.; Makii, H.; Nishinaka, I.; Orlandi, R.; Tsukada, K.; Smallcombe, J.; Chiba, S.; Aritomo, Y.; Ohtsuki, T.; Tatsuzawa, R.; Takaki, N.; Tamura, N.; Goto, S.; Tsekhanovich, I.; Petrache, C. M.; Andreyev, A. N.

    2016-10-01

    It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the 18O + 232Th reaction are used to study fission of fourteen nuclei 231,232,233,234Th, 232,233,234,235,236Pa, and 234,235,236,237,238U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of 231,234Th and 234,235,236Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation-dissipation model.

  4. Refolded scFv Antibody Fragment against Myoglobin Shows Rapid Reaction Kinetics

    PubMed Central

    Song, Hyung-Nam; Jang, Jun-Hyuck; Kim, Young-Wan; Kim, Dong-Hyung; Park, Sung-Goo; Lee, Myung Kyu; Paek, Se-Hwan; Woo, Eui-Jeon

    2014-01-01

    Myoglobin is one of the early biomarkers for acute myocardial infarction. Recently, we have screened an antibody with unique rapid reaction kinetics toward human myoglobin antigen. Antibodies with rapid reaction kinetics are thought to be an early IgG form produced during early stage of in vivo immunization. We produced a recombinant scFv fragment for the premature antibody from Escherichia coli using refolding technology. The scFv gene was constructed by connection of the VH–VL sequence with a (Gly4Ser)3 linker. The scFv fragment without the pelB leader sequence was expressed at a high level, but the solubility was extremely low. A high concentration of 8 M urea was used for denaturation. The dilution refolding process in the presence of arginine and the redox reagents GSH and GSSH successfully produced a soluble scFv protein. The resultant refolded scFv protein showed association and dissociation values of 9.32 × 10−4 M−1·s−1 and 6.29 × 10−3 s−1, respectively, with an affinity value exceeding 107 M−1 (kon/koff), maintaining the original rapid reaction kinetics of the premature antibody. The refolded scFv could provide a platform for protein engineering for the clinical application for diagnosis of heart disease and the development of a continuous biosensor. PMID:25530617

  5. Polymerase chain reaction-restriction fragment length polymorphism analysis of a 16S rRNA gene fragment for authentication of four clam species.

    PubMed

    Fernandez, Alicia; García, Teresa; Gonzalez, Isabel; Asensio, Luis; Rodriguez, Miguel Angel; Hernández, Pablo E; Martin, Rosario

    2002-04-01

    Specific identification of four clam species, Ruditapes decussatus (grooved carpet shell), Venerupis pullastra (pullet carpet shell), Ruditapes philippinarum (Japanese carpet shell), and Venerupis rhomboides (yellow carpet shell), was achieved by polymerase chain reaction-restriction fragment length polymorphism analysis of a fragment of the mitochondrial 16S rRNA gene. Amplification of DNA isolated from the foot muscle produced fragments of 511 bp for V. pullastra, 523 bp for R. decussatus, 545 bp for R. philippinarum, and 502 bp for V. rhomboides. The restriction profiles obtained by agarose gel electrophoresis when amplicons were digested with endonucleases BsmAI and BsrI allowed unequivocal identification of the four clam species. This approach would be less costly, simpler, and quicker than conventional sequencing of polymerase chain reaction products followed by detailed comparison of individual sequences, especially when large numbers of samples need to be analyzed.

  6. Protein hydrogen exchange studied by the fragment separation method.

    PubMed

    Englander, J J; Rogero, J R; Englander, S W

    1985-05-15

    The potential of hydrogen-exchange studies for providing detailed information on protein structure and structural dynamics has not yet been realized, largely because of the continuing inability to correlate measured exchange behavior with the parts of a protein that generate that behavior. J. Rosa and F. M. Richards (1979, J. Mol. Biol. 133, 399-416) pioneered a promising approach to this problem in which tritium label at exchangeable proton sites can be located by fragmenting the protein, separating the fragments, and measuring the label carried by each fragment. However, severe losses of tritium label during the fragment separation steps have so far rendered the results ambiguous. This paper describes methods that minimize losses of tritium label during the fragment separation steps and correct for losses that do occur so that the label can be unambiguously located and even quantified. Steps that promote adequate fragment isolation are also described.

  7. Protein Hydrogen Exchange Studied by the Fragment Separation Method

    PubMed Central

    Englander, Joan J.; Rogero, Jose R.; Englander, S. Walter

    2012-01-01

    The potential of hydrogen-exchange studies for providing detailed information on protein structure and structural dynamics has not yet been realized, largely because of the continuing inability to correlate measured exchange behavior with the parts of a protein that generate that behavior. J. Rosa and F. M. Richards (1979, J. Mol. Biol. 133, 399–416) pioneered a promising approach to this problem in which tritium label at exchangeable proton sites can be located by fragmenting the protein, separating the fragments, and measuring the label carried by each fragment. However, severe losses of tritium label during the fragment separation steps have so far rendered the results ambiguous. This paper describes methods that minimize losses of tritium label during the fragment separation steps and correct for losses that do occur so that the label can be unambiguously located and even quantified. Steps that promote adequate fragment isolation are also described. PMID:2992314

  8. Feasibility of Traveling Wave Direct Energy Conversion of Fission Reaction Fragments

    NASA Technical Reports Server (NTRS)

    Tarditi, A. G.; George, J. A.; Miley, G. H.; Scott, J. H.

    2013-01-01

    Fission fragment direct energy conversion has been considered in the past for the purpose of increasing nuclear power plant efficiency and for advanced space propulsion. Since the fragments carry electric charge (typically in the order of 20 e) and have 100 MeV-range kinetic energy, techniques utilizing very high-voltage DC electrodes have been considered. This study is focused on a different approach: the kinetic energy of the charged fission fragments is converted into alternating current by means of a traveling wave coupling scheme (Traveling Wave Direct Energy Converter, TWDEC), thereby not requiring the utilization of high voltage technology. A preliminary feasibility analysis of the concept is introduced based on a conceptual level study and on a particle simulation model of the beam dynamics.

  9. Radiation induced redox reactions and fragmentation of constituent ions in ionic liquids II. Imidazolium cations.

    SciTech Connect

    Shkrob, I. A.; Marin, T. W.; Chemerisov, S. D.; Hatcher, J.; Wishart, J.

    2011-04-14

    In part 1 of this study, radiolytic degradation of constituent anions in ionic liquids (ILs) was examined. The present study continues the themes addressed in part 1 and examines the radiation chemistry of 1,3-dialkyl substituted imidazolium cations, which currently comprise the most practically important and versatile class of ionic liquid cations. For comparison, we also examined 1,3-dimethoxy- and 2-methyl-substituted imidazolium and 1-butyl-4-methylpyridinium cations. In addition to identification of radicals using electron paramagnetic resonance spectroscopy (EPR) and selective deuterium substitution, we analyzed stable radiolytic products using {sup 1}H and {sup 13}C nuclear magnetic resonance (NMR) and tandem electrospray ionization mass spectrometry (ESMS). Our EPR studies reveal rich chemistry initiated through 'ionization of the ions': oxidation and the formation of radical dications in the aliphatic arms of the parent cations (leading to deprotonation and the formation of alkyl radicals in these arms) and reduction of the parent cation, yielding 2-imidazolyl radicals. The subsequent reactions of these radicals depend on the nature of the IL. If the cation is 2-substituted, the resulting 2-imidazolyl radical is relatively stable. If there is no substitution at C(2), the radical then either is protonated or reacts with the parent cation forming a C(2)-C(2) {sigma}{sigma}*-bound dimer radical cation. In addition to these reactions, when methoxy or C{sub {alpha}}-substituted alkyl groups occupy the N(1,3) positions, their elimination is observed. The elimination of methyl groups from N(1,3) was not observed. Product analyses of imidazolium liquids irradiated in the very-high-dose regime (6.7 MGy) reveal several detrimental processes, including volatilization, acidification, and oligomerization. The latter yields a polymer with m/z of 650 {+-} 300 whose radiolytic yield increases with dose (0.23 monomer units per 100 eV for 1-methyl-3-butylimidazolium

  10. Radiation induced redox reactions and fragmentation of constituent ions in ionic liquids. 2. Imidazolium cations.

    PubMed

    Shkrob, Ilya A; Marin, Timothy W; Chemerisov, Sergey D; Hatcher, Jasmine L; Wishart, James F

    2011-04-14

    In part 1 of this study, radiolytic degradation of constituent anions in ionic liquids (ILs) was examined. The present study continues the themes addressed in part 1 and examines the radiation chemistry of 1,3-dialkyl substituted imidazolium cations, which currently comprise the most practically important and versatile class of ionic liquid cations. For comparison, we also examined 1,3-dimethoxy- and 2-methyl-substituted imidazolium and 1-butyl-4-methylpyridinium cations. In addition to identification of radicals using electron paramagnetic resonance spectroscopy (EPR) and selective deuterium substitution, we analyzed stable radiolytic products using (1)H and (13)C nuclear magnetic resonance (NMR) and tandem electrospray ionization mass spectrometry (ESMS). Our EPR studies reveal rich chemistry initiated through "ionization of the ions": oxidation and the formation of radical dications in the aliphatic arms of the parent cations (leading to deprotonation and the formation of alkyl radicals in these arms) and reduction of the parent cation, yielding 2-imidazolyl radicals. The subsequent reactions of these radicals depend on the nature of the IL. If the cation is 2-substituted, the resulting 2-imidazolyl radical is relatively stable. If there is no substitution at C(2), the radical then either is protonated or reacts with the parent cation forming a C(2)-C(2) σσ*-bound dimer radical cation. In addition to these reactions, when methoxy or C(α)-substituted alkyl groups occupy the N(1,3) positions, their elimination is observed. The elimination of methyl groups from N(1,3) was not observed. Product analyses of imidazolium liquids irradiated in the very-high-dose regime (6.7 MGy) reveal several detrimental processes, including volatilization, acidification, and oligomerization. The latter yields a polymer with m/z of 650 ± 300 whose radiolytic yield increases with dose (~0.23 monomer units per 100 eV for 1-methyl-3-butylimidazolium trifluorosulfonate). Gradual

  11. Cyclization and rearrangement reactions of a(n) fragment ions of protonated peptides.

    PubMed

    Bythell, Benjamin J; Maître, Philippe; Paizs, Béla

    2010-10-27

    a(n) ions are frequently formed in collision-induced dissociation (CID) of protonated peptides in tandem mass spectrometry (MS/MS) based sequencing experiments. These ions have generally been assumed to exist as immonium derivatives (-HN(+)═CHR). Using a quadrupole ion trap mass spectrometer, MS/MS experiments have been performed and the structure of a(n) ions formed from oligoglycines was probed by infrared spectroscopy. The structure and isomerization reactions of the same ions were studied using density functional theory. Overall, theory and infrared spectroscopy provide compelling evidence that a(n) ions undergo cyclization and/or rearrangement reactions, and the resulting structure(s) observed under our experimental conditions depends on the size (n). The a(2) ion (GG sequence) undergoes cyclization to form a 5-membered ring isomer. The a(3) ion (GGG sequence) undergoes cyclization initiated by nucleophilic attack of the carbonyl oxygen of the N-terminal glycine residue on the carbon center of the C-terminal immonium group forming a 7-membered ring isomer. The barrier to this reaction is comparatively low at 10.5 kcal mol(-1), and the resulting cyclic isomer (-5.4 kcal mol(-1)) is more energetically favorable than the linear form. The a(4) ion with the GGGG sequence undergoes head-to-tail cyclization via nucleophilic attack of the N-terminal amino group on the carbon center of the C-terminal immonium ion, forming an 11-membered macroring which contains a secondary amine and three trans amide bonds. Then an intermolecular proton transfer isomerizes the initially formed secondary amine moiety (-CH(2)-NH(2)(+)-CH(2)-NH-CO-) to form a new -CH(2)-NH-CH(2)-NH(2)(+)-CO- form. This structure is readily cleaved at the -CH(2)-NH(2)(+)- bond, leading to opening of the macrocycle and formation of a rearranged linear isomer with the H(2)C═NH(+)-CH(2)- moiety at the N terminus and the -CO-NH(2) amide bond at the C terminus. This rearranged linear structure is much more

  12. Polymerase chain reaction-restriction fragment length polymorphism authentication of raw meats from game birds.

    PubMed

    Rojas, María; González, Isabel; Fajardo, Violeta; Martín, Irene; Hernández, Pablo E; García, Teresa; Martín, Rosario

    2008-01-01

    Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis has been applied to the identification of meats from quail (Coturnix coturnix), pheasant (Phasianus colchicus), red-legged partridge (Alectoris rufa), guinea fowl (Numida meleagris), capercaillie (Tetrao urogallus), Eurasian woodcock (Scolopax rusticola), woodpigeon (Columba palumbus), and song thrush (Turdus philomelos). PCR amplification was performed using a set of primers flanking a conserved region of approximately 720 base pairs (bp) from the mitochondrial 12S rRNA gene. Restriction site analysis based on sequence data from this DNA fragment permitted the selection of AluI and BfaI endonucleases for species identification. The restriction profiles obtained when amplicons were digested with the chosen enzymes allowed the unequivocal identification of all game bird species analyzed. However, the use of the PCR-RFLP technique described is limited to raw meat authentication. It is not suitable for cooked products because thermal treatment strongly accelerates DNA degradation leading to difficulties in amplifying the 720 bp fragment.

  13. Experimental studies of collision and fragmentation phenomena

    NASA Technical Reports Server (NTRS)

    Hartmann, William K.; Davis, D. R.; Weidenschilling, S. J.

    1987-01-01

    The reduction and publication of an extensive data set collected in experiments over several years at Ames and PSI is briefly examined. Hartmann has been assembling data sets from his experiments on catastrophic fragmentation of various materials, including basalt, other igneous rock, ice, and weak dirt clods. Weidenschilling and Davis have continued to gather and reduce data on oblique impacts. The data indicate a power law distribution of ejecta mass vs. velocity, with a slope that is independent of azimuth, and does not vary with impact angle from normal impacts to at least 75 deg from vertical. In order to improve models of coagulation of dust aggregates in the solar nebula, SJW developed an apparatus for drop tests of fragile projectiles. Davis and Weidenschilling continued to collect and analyze experimental data on collisional catastrophic disruption at the Ames Vertical Gun Range.

  14. Global transformation and fate of SOA: Implications of Low Volatility SOA and Gas-Phase Fragmentation Reactions

    SciTech Connect

    Shrivastava, ManishKumar B.; Easter, Richard C.; Liu, Xiaohong; Zelenyuk, Alla; Singh, Balwinder; Zhang, Kai; Ma, Po-Lun; Chand, Duli; Ghan, Steven J.; Jiminez, J. L.; Zhang, Qibin; Fast, Jerome D.; Rasch, Philip J.; Tiitta, P.

    2015-05-16

    Secondary organic aerosols (SOA) are large contributors to fine particle loadings and radiative forcing, but are often represented crudely in global models. We have implemented three new detailed SOA treatments within the Community Atmosphere Model version 5 (CAM5) that allow us to compare the semi-volatile versus non-volatile SOA treatments (based on some of the latest experimental findings) and also investigate the effects of gas-phase fragmentation reactions. For semi-volatile SOA treatments, fragmentation reactions decrease simulated SOA burden from 7.5 Tg to 1.8 Tg. For the non-volatile SOA treatment with fragmentation, the burden is 3.1 Tg. Larger differences between non-volatile and semi-volatile SOA (upto a factor of 5) correspond to continental outflow over the oceans. Compared to a global dataset of surface Aerosol Mass Spectrometer measurements and the US IMPROVE network measurements, the non-volatile SOA with fragmentation treatment (FragNVSOA) agrees best at rural locations. Urban SOA is under-predicted but this may be due to the coarse model resolution. All our three revised treatments show much better agreement with aircraft measurements of organic aerosols (OA) over the N. American Arctic and sub-Arctic in spring and summer, compared to the standard CAM5 formulation. This is due to treating SOA precursor gases from biomass burning, and long-range transport of biomass burning OA at elevated levels. The revised model configuration that include fragmentation (both semi-volatile and non-volatile SOA) show much better agreement with MODIS AOD data over regions dominated by biomass burning during the summer, and predict biomass burning as the largest global source of OA followed by biogenic and anthropogenic sources. The non-volatile and semi-volatile configuration predict the direct radiative forcing of SOA as -0.5 W m-2 and -0.26 W m-2 respectively, at top of the atmosphere, which are higher than previously estimated by most models, but in reasonable

  15. Rock fragment movement in shallow rill flow - A laboratory study

    NASA Astrophysics Data System (ADS)

    Becker, Kerstin; Wirtz, Stefan; Seeger, Manuel; Gronz, Oliver; Remke, Alexander; Iserloh, Thomas; Brings, Christine; Casper, Markus; Ries, Johannes B.

    2014-05-01

    Studies concerning rill erosion mainly deal with the erosion and transport of fine material. The transport of rock fragments is examined mostly for mountain rivers. But there are important differences between the conditions and processes in rivers and in rills: (1) In most cases, the river cuts into a coarse substrate, where fine material is sparse, whereas rill erosion occurs on arable land. So the main part of the substrate is fine material and only single rock fragments influence the processes. (2) In rivers, the water depth is relatively high. There are a lot of studies about hydraulic parameters in such flows, but there is almost nothing known about hydraulic conditions in surface runoff events of a few centimeters. Additionally, little information exists about the rock fragment movement as a part of rill erosion processes on arable land. This knowledge should be increased because rock fragments cause non-stationary water turbulences in rills, which enhance the erosive force of flowing water. Field experiments can only show the fact that a certain rock fragment has moved: The starting point and the final position can be estimated. But the moving path and especially the initiation of the movement is not detectable under field conditions. Hence, we developed a laboratory setup to analyze the movement of rock fragments depending on rock fragment properties (size, form), slope gradient, flow velocity and surface roughness. By observing the rock fragments with cameras from two different angles we are able (1) to measure the rotation angles of a rock fragment during the experiment and (2) to deduce different rock fragment movement patterns. On this poster we want to present the experimental setup, developed within the scope of a master thesis, and the results of these experiments.

  16. Reaction between radicals and N-alkoxyamines As coordinated cleavage with fragmentation

    NASA Astrophysics Data System (ADS)

    Denisov, E. T.; Shestakov, A. F.

    2015-08-01

    Quantum chemical calculations of the enthalpy and activation energy of two reactions with MeO{2/⊙} attacking the CH- and CH2-groups of 2,2,6,6-tetramethylpiperidineoxy-2'-butane are performed. It is shown that the cleavage of hydrogen atoms is accompanied by coordinated breaking of N-O-bonds in the former case and C-O-bonds in the latter. Based on the obtained results, a new scheme is proposed for the cyclic mechanism behind the cleavage of chains on nitroxyl radicals in oxidizing hydrocarbons and polymers that agrees with experimental data. At the center of this cyclic mechanism lies the fast exothermic reaction between peroxyl radicals and N-alkoxyamine with the cleavage of H atoms and the coordinated fragmentation of molecules. Using the model of intersecting parabolas, an algorithm for calculating the enthalpies, activation energies, and rate constants of these reactions with the participation of alkyl, alkoxy, aminyl, peroxyl, phenoxyl, thiyl, and hydroxyl radicals is proposed.

  17. Holliday junctions generate super-bright antibodies and antibody fragments in sortase-catalyzed reactions

    PubMed Central

    Li, Zeyang; Theile, Christopher S.; Chen, Guan-Yu; Bilate, Angelina M.; Duarte, Joao N.; Avalos, Ana M.; Fang, Tao; Barberena, Roberto; Sato, Shuji; Ploegh, Hidde L.

    2015-01-01

    Site-specific modification of proteins with fluorophores can render a protein fluorescent without compromising its function. To avoid self-quenching of multiple fluorophores installed in close proximity, we used Holliday junctions to label proteins site-specifically. Holliday junctions enable modification with multiple fluorophores at reasonably precise spacing. We designed a Holliday junction with three of its four arms modified with a fluorophore of choice and the remaining arm equipped with a dibenzocyclooctyne substituent to render it reactive with an azide-modified, fluorescent single domain antibody fragment or an intact immunoglobulin, produced in a sortase-catalyzed reaction. We conclude that fluorescent Holliday junctions improve fluorescence yields for both single domain and full-sized antibodies, without deleterious effects on antigen binding. PMID:26252716

  18. Fission Cross Sections and Fission-Fragment Mass Yields via the Surrogate Reaction Method

    SciTech Connect

    Jurado, B.; Kessedjian, G.; Aiche, M.; Barreau, G.; Bidaud, A.; Czajkowski, S.; Dassie, D.; Haas, B.; Mathieu, L.; Osmanov, B.; Ahmad, I.

    2008-04-17

    The surrogate reaction method is a powerful tool to infer neutron-induced data of short-lived nuclei. After a short overview of the experimental techniques employed in the present surrogate experiments, we will concentrate on a recent measurement to determine neutron-induced fission cross sections for the actinides {sup 242,243}Cm and {sup 241}Am. The latest direct neutron-induced measurement for the {sup 243}Cm fission cross section is questioned by our results, since there are differences of more than 60% in the 0.7 to 7 MeV neutron energy range. Our experimental set-up has also enabled us to measure for the first time the fission fragment ''pseudo-mass'' distributions of {sup 243,244,245}Cm and {sup 242}Am compound nuclei in the excitation energy range from a few MeV to about 25 MeV.

  19. QUICK REACTION STUDIES.

    DTIC Science & Technology

    The functional requirements of mission planning of space missions are documented. A discussion of the current applicable computer programs to some part of the mission planning process is included. In particular the Mission Analysis and Trajectory Simulation (MATS) system is described. The applicability of current programs to the demands of mission planning in a Quick Reaction

  20. Light Charged Particles and Intermediate Mass Fragments from the Reactions 486, 550, 640, and 730 Mev KRYPTON-86 + COPPER-63

    NASA Astrophysics Data System (ADS)

    Boger, John Thomas

    1992-01-01

    A detailed study has been made of the reaction ^{86}Kr + ^ {63}Cu at incident energies of 486, 550, 640, and 730 MeV. Measurements include cross sections, angular distributions, and energy spectra for light charged particles (^{1,2,3}H and ^4He), intermediate mass fragments (IMF) (4 <= Z <= 17), and heavy fragments (Z >= 18). Coincidences between light charged particles and between particles and fragments have also been measured to obtain exclusive cross sections, energy spectra, and angular distributions. Statistical model analysis of the energy spectra for ^1 H and ^4He detected in coincidence with the fragments has allowed estimation of ^1 H and ^4He multiplicities associated with the evaporation residues, fragments, and composite nuclei prior to scission. In particular, the light charged particle multiplicities for the IMF's have allowed for the derivation of their primary masses. This in turn has permitted refined measurements of the kinetic energies of the primary IMF's. The ^{86}Kr bombarding energies were selected so that the excitation energies of the composite nuclei (^{149} Tb*) were matched to those of other entrance channel reactions that produce the same composite nuclei. A close comparison of cross sections, energy spectra, angular distributions, and particle multiplicities for these matched entrance channels has provided the means for a detailed test of the Bohr Independence Hypothesis. Results of this comparison indicate extensive shape and thermal equilibration of the composite nuclei over the excitation energy range of 128 to 231 MeV. This conclusion is reached even for nuclear systems whose decay lifetimes are expected to be similar to their relaxation times. For the 640 MeV ^{86} Kr + ^{63}Cu reaction, cross sections were measured for IMF's of 4 <= Z <= 17 in singles and in coincidence with heavy fragments. Three sources for IMF production have been identified: (1) asymmetric binary fission, (2) sequential binary fission, and (3) simultaneous

  1. Physical and dynamical studies of meteors. [radar observation of fragmentation

    NASA Technical Reports Server (NTRS)

    Southworth, R. B.; Sekanina, Z.

    1974-01-01

    Distribution of meteors in streams detected in the synoptic-year meteor sample plus a study of the fragmentation characteristics of the synoptic-year meteor sample are presented. Population coefficients and dispersion coefficients were determined for each meteor stream. These two parameters serve to determine the number of definite members of the stream in the sample used, and to estimate the actual space density of meteor streams. From results of the fragmentation study, it appears that the main body of most radar meteors does not ablate fragments layer by layer, but collapses rather suddenly under dynamic pressures on the order of 0,0002 dynes/cm. Furthermore, it is believed that fragmentation does not cause a serious selection effect in the radar meteor data.

  2. Electrochemical aptameric sensor based on the Klenow fragment polymerase reaction for cocaine detection.

    PubMed

    He, Jing-Lin; Yang, Yi-Feng; Shen, Guo-Li; Yu, Ru-Qin

    2011-06-15

    An electrochemical aptasensor based on Klenow fragment (KF) polymerase reaction that combines the aggregation of ferrocene-functionalized oligonucleotide has been developed successfully for cocaine detection. In the presence of cocaine, the recognition probe changed its hairpin conformation into the tripartite complex. The aptamer-cocaine complex gave a 3'-single-stranded tail sequence complementary to the surface-tethered capture probe. In KF polymerase reaction, the recognition probe served as a template for the extension of a capture probe. It requires a sample volume of 2 μL and is complete within 1 h. The ferrocene-appended oligonucleotide incorporated into the newly synthesized complementary probe leads to an electrochemical response. This sensitive detection of cocaine is due to a very low background signal and large signal enhancement up to 9-fold upon addition of analyte. It permits detection of as low as 200 μM cocaine. The simple and isothermal procedure does not require thermal cycling or special laboratory conditions, which makes it adaptable to low-cost and robust biosensing. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. A thermodynamic molecular switch in biological systems: ribonuclease S' fragment complementation reactions.

    PubMed Central

    Chun, P W

    2000-01-01

    It is well known that essentially all biological systems function over a very narrow temperature range. Most typical macromolecular interactions show DeltaH degrees (T) positive (unfavorable) and a positive DeltaS degrees (T) (favorable) at low temperature, because of a positive (DeltaCp degrees /T). Because DeltaG degrees (T) for biological systems shows a complicated behavior, wherein DeltaG degrees (T) changes from positive to negative, then reaches a negative value of maximum magnitude (favorable), and finally becomes positive as temperature increases, it is clear that a deeper-lying thermodynamic explanation is required. This communication demonstrates that the critical factor is a temperature-dependent DeltaCp degrees (T) (heat capacity change) of reaction that is positive at low temperature but switches to a negative value at a temperature well below the ambient range. Thus the thermodynamic molecular switch determines the behavior patterns of the Gibbs free energy change and hence a change in the equilibrium constant, K(eq), and/or spontaneity. The subsequent, mathematically predictable changes in DeltaH degrees (T), DeltaS degrees (T), DeltaW degrees (T), and DeltaG degrees (T) give rise to the classically observed behavior patterns in biological reactivity, as may be seen in ribonuclease S' fragment complementation reactions. PMID:10620305

  4. Experimental and numerical study on fragmentation of steel projectiles

    NASA Astrophysics Data System (ADS)

    Råkvaag, K. G.; Børvik, T.; Hopperstad, O. S.; Westermann, I.

    2012-08-01

    A previous experimental study on penetration and perforation of circular Weldox 460E target plates with varying thicknesses struck by blunt-nose projectiles revealed that fragmentation of the projectile occurred if the target thickness or impact velocity exceeded a certain value. Thus, numerical simulations that do not account for fragmentation during impact can underestimate the perforation resistance of protective structures. Previous numerical studies have focused primarily on the target plate behaviour. This study considers the behaviour of the projectile and its possible fragmentation during impact. Hardened steel projectiles were launched at varying velocities in a series of Taylor tests. The impact events were captured using a high-speed camera. Fractography of the fragmented projectiles showed that there are several fracture mechanisms present during the fragmentation process. Tensile tests of the projectile material revealed that the hardened material has considerable variations in yield stress and fracture stress and strain. In the finite element model, the stress-strain behaviour from tensile tests was used to model the projectile material with solid elements and the modified Johnson-Cook constitutive relation. Numerical simulations incorporating the variations in material properties are capable of reproducing the experimental fracture patterns, albeit the predicted fragmentation velocities are too low.

  5. Global Transformation and Fate of Secondary Organic Aerosols: Implications of Low Volatility SOA and Gas-Phase Fragmentation Reactions

    NASA Astrophysics Data System (ADS)

    Shrivastava, M. B.; Easter, R. C.; Liu, X.; Zelenyuk, A.; Singh, B.; Zhang, K.; Ma, P. L.; Chand, D.; Ghan, S. J.; Jimenez, J. L.; Zhang, Q.; Fast, J. D.; Rasch, P. J.; Tiitta, P.

    2014-12-01

    Secondary organic aerosols (SOA) are often represented crudely in global models. We have implemented three new detailed SOA treatments within the Community Atmosphere Model version 5 (CAM5) that allow us to compare the semi-volatile versus non-volatile SOA treatments (based on some of the latest experimental findings) and also investigate the effects of gas-phase fragmentation reactions. For semi-volatile SOA treatments, fragmentation reactions decrease simulated SOA burden from 7.5 Tg to 1.8 Tg. For the non-volatile SOA treatment (with fragmentation), the burden is 3.1 Tg. Larger differences between non-volatile and semi-volatile SOA (upto a factor of 5) correspond to continental outflow over the oceans. Compared to a global dataset of surface Aerosol Mass Spectrometer measurements and the US IMPROVE network measurements, the non-volatile SOA with fragmentation treatment (FragNVSOA) agrees best at rural locations. Urban SOA is under-predicted but this may be due to the coarse model resolution. Our revised treatments show much better agreement with aircraft measurements of organic aerosols (OA) over the N. American Arctic and sub-Arctic in spring and summer, compared to the standard CAM5 formulation. This is due to treating SOA precursor gases from biomass burning, and long-range transport of biomass burning OA at elevated levels (also supported by satellite data), which undergoes less wet removal compared to the surface OA sources in the standard CAM5. Although the total simulated OA from biomass burning agrees better with aircraft measurements, recent field observations typically report lower SOA formation, suggesting that constraining the POA-SOA split from biomass burning should be the focus of future studies. The non-volatile and semi-volatile configurations predict the direct radiative forcing of SOA as -0.5 W m-2 and -0.26 W m-2 respectively, at top of the atmosphere, which are higher than previously estimated by most models, but in reasonable agreement with

  6. A polymerase chain reaction-restriction fragment length polymorphism method for screening ZNF804A gene polymorphism (rs1344706) in patients with schizophrenia: a significant association.

    PubMed

    Sazci, Ali; Ozel, Mavi Deniz; Ergul, Emel; Yildiz, Mustafa

    2012-03-01

    The original ZNF804A rs1344706 risk variant was identified through genome-wide association studies as a risk factor for schizophrenia. Follow-up studies involving meta-analysis have confirmed that rs1344706 is a risk factor for schizophrenia as well as bipolar disorders. We describe here a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method to genotype ZNF804A rs1344706 variant in patients with schizophrenia. We generated a 220 bp fragment through PCR and subsequently cleaved it by the restriction endonuclease BsaBI, creating two fragments of 114 and 106 bp. Upon change in the nucleotide from T to G, the 106 bp fragment is further cleaved by BsaBI, thus creating two fragments of 87 and 19 bp. As a result, when the 220 bp fragment is cleaved by BsaBI restriction endonuclease, the TT genotype yields two fragments of 114 and 106 bp, and TG genotype four fragments of 114, 106, 87, and 19 bp, and the GG genotype three fragments of 114, 87, and 19 bp. Thus, this is a simple, fast, and cost-effective method to genotype the ZNF804A rs1344706 risk variant. Using this method, we were able to replicate an association between ZNF804A rs1344706 variant and schizophrenia in a Turkish population. Stratification analysis of the population according to the gender showed an association that was statistically significant among overall schizophrenia and male schizophrenia and the risk T allele and TT genotype of the ZNF804A gene.

  7. Analyzing fragment production in mass-asymmetric reactions as a function of density dependent part of symmetry energy

    SciTech Connect

    Kaur, Amandeep; Deepshikha; Vinayak, Karan Singh; Kumar, Suneel

    2016-07-15

    We performed a theoretical investigation of different mass-asymmetric reactions to access the direct impact of the density-dependent part of symmetry energy on multifragmentation. The simulations are performed for a specific set of reactions having same system mass and N/Z content, using isospin-dependent quantum molecular dynamics model to estimate the quantitative dependence of fragment production on themass-asymmetry factor (τ) for various symmetry energy forms. The dynamics associated with different mass-asymmetric reactions is explored and the direct role of symmetry energy is checked. Also a comparison with the experimental data (asymmetric reaction) is presented for a different equation of states (symmetry energy forms).

  8. Genetic divergence between Mexican Opuntia accessions inferred by polymerase chain reaction-restriction fragment length polymorphism analysis.

    PubMed

    Samah, S; Valadez-Moctezuma, E; Peláez-Luna, K S; Morales-Manzano, S; Meza-Carrera, P; Cid-Contreras, R C

    2016-06-03

    Molecular methods are powerful tools in characterizing and determining relationships between plants. The aim of this study was to study genetic divergence between 103 accessions of Mexican Opuntia. To accomplish this, polymerase chain reaction (PCR)-restriction fragment length polymorphism analysis of three chloroplast intergenic spacers (atpB-rbcL, trnL-trnF, and psbA-trnH), one chloroplast gene (ycf1), two nuclear genes (ppc and PhyC), and one mitochondrial gene (cox3) was conducted. The amplified products from all the samples had very similar molecular sizes, and there were only very small differences between the undigested PCR amplicons for all regions, with the exception of ppc. We obtained 5850 bp from the seven regions, and 136 fragments were detected with eight enzymes, 37 of which (27.2%) were polymorphic. We found that 40% of the fragments from the chloroplast regions were polymorphic, 9.8% of the bands detected in the nuclear genes were polymorphic, and 20% of the bands in the mitochondrial locus were polymorphic. trnL-trnF and psbA-trnH were the most variable regions. The Nei and Li/Dice distance was very short, and ranged from 0 to 0.12; indeed, 77 of the 103 genotypes had the same genetic profile. All the xoconostle accessions (acidic fruits) were grouped together without being separated from three genotypes of prickly pear (sweet fruits). We assume that the genetic divergence between prickly pears and xoconostles is very low, and question the number of Opuntia species currently considered in Mexico.

  9. Taxonomic and ecological discrimination of Fagaceae species based on internal transcribed spacer polymerase chain reaction-restriction fragment length polymorphism.

    PubMed

    Coutinho, João Paulo; Carvalho, Ana; Lima-Brito, José

    2014-11-26

    The internal transcribed spacer (ITS) of ribosomal DNA has been used to confirm taxonomic classifications and define phylogenies in several plant species following sequencing or polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques. In this study, co-dominant ITS PCR-RFLP molecular markers were produced in 30 Fagaceae individuals belonging to the Castanea, Fagus and Quercus genera in order to assess the potential of this technique for taxonomic discrimination and determination of phylogenies. The complete ITS region (ITS1-5.8S rRNA-ITS2) was amplified in most of the Fagaceae individuals as a single fragment of ∼700 bp. The ITS amplified products were digested with nine restriction enzymes, but only four (HaeIII, HpaII, TaqI and Sau96I) produced polymorphic/discriminative patterns. The total expected heterozygosity (HE) was 20.31 % and the gene diversity (I), 32.97 %. The ITS polymorphism was higher within the Quercus genus (85.3 %). The ITS PCR-RFLP markers clustered the Fagaceae species according to genus or infrageneric group (in the case of Quercus sp. individuals). Five oaks did not cluster in line with the adopted infrageneric classification, but three of these were grouped according to their actual ecological distributions. The ITS PCR-RFLP markers indicated their potential for phylogenetic studies since all Fagaceae individuals were discriminated according to genus, and most of the oaks were clustered according to infrageneric group or ecological area.

  10. Effect of projectile breakup on fission-fragment mass distributions in the Li,76 + 238U reactions

    NASA Astrophysics Data System (ADS)

    Santra, S.; Pal, A.; Rath, P. K.; Nayak, B. K.; Singh, N. L.; Chattopadhyay, D.; Behera, B. R.; Singh, Varinderjit; Jhingan, A.; Sugathan, P.; Golda, K. S.; Sodaye, S.; Appannababu, S.; Prasad, E.; Kailas, S.

    2014-12-01

    Background: Detailed studies on the effect of the breakup of weakly bound projectile on fission are scarce. Distinguishing the events of compound nuclear (CN) fission from the breakup or transfer induced fission to understand the properties of measured fission fragments is difficult but desirable. Purpose: To investigate the effect of projectile breakup and its breakup threshold energy on fission-fragment (FF) mass distributions and folding angle distributions for Li,76 + 238U reactions and find out the differences in the properties of the fission events produced by complete fusion (CF) from the total fusion (TF). Methods: The FF mass and folding angle distributions have been measured at energies around the Coulomb barrier using gas detectors by time-of-flight technique. The results are compared with the ones involving tightly bound projectiles as well as predictions from systematics to bring out the effect of the breakup. Results: A sharp increase in the peak to valley (P:V) ratio of FF mass distribution with the decrease in bombarding energy for Li,76 + 238U reactions is observed when all events are assumed to be CN fission. As the beam energy falls through the fusion barrier, the full width half maximum (FWHM) of the FF folding angle distribution is found to increase at sub-barrier energies, unlike the reactions involving tightly bound projectiles where a linear decrease in FWHM is expected. By selecting pure CN events from the scatter plot of the velocity components of the composite nuclei, the energy dependence of the deduced FWHM is found to be consistent with the ones involving tightly bound projectiles. Similarly, the P:V ratio obtained for the selected CN events is consistent with the theoretical calculations as well as the experimental data for the proton induced reaction forming similar CN. Conclusions: The presence of projectile breakup induced fission and a relatively low breakup threshold for 6Li compared to 7Li explains the observed differences in

  11. Yield ratios and directed flows of light fragments from reactions induced by neutron-rich nuclei at intermediate energy

    NASA Astrophysics Data System (ADS)

    Yan, Ting-Zhi; Li, Long-Long; Wang, Rui-Feng; Yan, Ting-Feng

    2017-04-01

    The yield ratios of neutron/proton and 3H/3He and the directed flow per nucleon for these projectile-like fragments at large impact parameters are studied for 50Ca + 40Ca and 50Cr + 40Ca for comparison at 50 MeV/u using the isospin-dependent quantum molecular dynamics (IQMD) model. It is found that the yield ratios and the directed flows per nucleon are different for reactions induced by the neutron-rich nucleus 50Ca and the stable isobaric nucleus 50Cr, and depend on the hardness of the EOS. The ratios of neutron/proton and 3H/3He and the difference of directed flow per nucleon of neutron-proton are suggested to be possible observables to investigate the isospin effects. Supported by National Natural Science Foundation of China (11405025)

  12. Comprehensive Study On The Metastable Negative Ion Fragmentation Of Individual Dna Components And Larger Oligonucleotides

    NASA Astrophysics Data System (ADS)

    Ingolfsson, O.; Flosadottir, H. D.; Omarsson, B.; Ilko, B.

    2010-07-01

    Here we present a systematic study on the unimolecular decay pathways of the deprotonated building blocks of DNA and RNA to address the following questions: 1. Are the negative ion fragmentation patterns observed in the metastable decay of individual DNA components still evident when these are combined to larger oligonucleotides? 2. What is the significance of the charge location in determining the fragmentation pathways in the metastable decay process? 3. Are those metastable decay channels relevant in dissociative electron attachment to DNA components? To address these questions we have studied the fragmentation patterns of the deprotonated ribose and ribose 5'-monophosphate, the fragmentation patterns of the individual bases, all nucleosides and all 2'-deoxynucleosides as well as the individual nucleotides and several combinations of hexameric oligonucleotides. Furthermore, to understand the significance of the charge location in determining the fragmentation path in the metastable decay process of these deprotonated ions we have also studied modified uridine and guanosine. These have been modified to block different deprotonation sites and thus to control the initial step in the in the fragmentation process i.e. the site of deprotonation. In addition to our experimental approach we have also simulated the metastable fragmentation of the deprotonated uridine and 2'-deoxyguanosine to clarify the mechanisms and fragmentation patterns observed. Where data is available, the results are compared to dissociative electron attachment to DNA components and discussed in context to the underlying mechanism. Experiments on modified nucleosides where selected deprotonation sites have been blocked are used to verify the predicted reaction paths and imulations on uridine and 2'-deoxyguanosine are compared to the experimental results and used to shed light on the mechanisms involved.

  13. Anomalies in the Charge Yields of Fission Fragments from the ^{238}U(n,f) Reaction.

    PubMed

    Wilson, J N; Lebois, M; Qi, L; Amador-Celdran, P; Bleuel, D; Briz, J A; Carroll, R; Catford, W; De Witte, H; Doherty, D T; Eloirdi, R; Georgiev, G; Gottardo, A; Goasduff, A; Hadyńska-Klęk, K; Hauschild, K; Hess, H; Ingeberg, V; Konstantinopoulos, T; Ljungvall, J; Lopez-Martens, A; Lorusso, G; Lozeva, R; Lutter, R; Marini, P; Matea, I; Materna, T; Mathieu, L; Oberstedt, A; Oberstedt, S; Panebianco, S; Podolyák, Zs; Porta, A; Regan, P H; Reiter, P; Rezynkina, K; Rose, S J; Sahin, E; Seidlitz, M; Serot, O; Shearman, R; Siebeck, B; Siem, S; Smith, A G; Tveten, G M; Verney, D; Warr, N; Zeiser, F; Zielinska, M

    2017-06-02

    Fast-neutron-induced fission of ^{238}U at an energy just above the fission threshold is studied with a novel technique which involves the coupling of a high-efficiency γ-ray spectrometer (MINIBALL) to an inverse-kinematics neutron source (LICORNE) to extract charge yields of fission fragments via γ-γ coincidence spectroscopy. Experimental data and fission models are compared and found to be in reasonable agreement for many nuclei; however, significant discrepancies of up to 600% are observed, particularly for isotopes of Sn and Mo. This indicates that these models significantly overestimate the standard 1 fission mode and suggests that spherical shell effects in the nascent fission fragments are less important for low-energy fast-neutron-induced fission than for thermal neutron-induced fission. This has consequences for understanding and modeling the fission process, for experimental nuclear structure studies of the most neutron-rich nuclei, for future energy applications (e.g., Generation IV reactors which use fast-neutron spectra), and for the reactor antineutrino anomaly.

  14. Anomalies in the Charge Yields of Fission Fragments from the 238U (n ,f ) Reaction

    NASA Astrophysics Data System (ADS)

    Wilson, J. N.; Lebois, M.; Qi, L.; Amador-Celdran, P.; Bleuel, D.; Briz, J. A.; Carroll, R.; Catford, W.; De Witte, H.; Doherty, D. T.; Eloirdi, R.; Georgiev, G.; Gottardo, A.; Goasduff, A.; Hadyńska-Klek, K.; Hauschild, K.; Hess, H.; Ingeberg, V.; Konstantinopoulos, T.; Ljungvall, J.; Lopez-Martens, A.; Lorusso, G.; Lozeva, R.; Lutter, R.; Marini, P.; Matea, I.; Materna, T.; Mathieu, L.; Oberstedt, A.; Oberstedt, S.; Panebianco, S.; Podolyák, Zs.; Porta, A.; Regan, P. H.; Reiter, P.; Rezynkina, K.; Rose, S. J.; Sahin, E.; Seidlitz, M.; Serot, O.; Shearman, R.; Siebeck, B.; Siem, S.; Smith, A. G.; Tveten, G. M.; Verney, D.; Warr, N.; Zeiser, F.; Zielinska, M.

    2017-06-01

    Fast-neutron-induced fission of 238U at an energy just above the fission threshold is studied with a novel technique which involves the coupling of a high-efficiency γ -ray spectrometer (MINIBALL) to an inverse-kinematics neutron source (LICORNE) to extract charge yields of fission fragments via γ -γ coincidence spectroscopy. Experimental data and fission models are compared and found to be in reasonable agreement for many nuclei; however, significant discrepancies of up to 600% are observed, particularly for isotopes of Sn and Mo. This indicates that these models significantly overestimate the standard 1 fission mode and suggests that spherical shell effects in the nascent fission fragments are less important for low-energy fast-neutron-induced fission than for thermal neutron-induced fission. This has consequences for understanding and modeling the fission process, for experimental nuclear structure studies of the most neutron-rich nuclei, for future energy applications (e.g., Generation IV reactors which use fast-neutron spectra), and for the reactor antineutrino anomaly.

  15. Anomalies in the Charge Yields of Fission Fragments from the U(n,f)238 Reaction

    DOE PAGES

    Wilson, J. N.; Lebois, M.; Qi, L.; ...

    2017-06-01

    Fast-neutron-induced fission of 238U at an energy just above the fission threshold is studied with a novel technique which involves the coupling of a high-efficiency γ-ray spectrometer (MINIBALL) to an inverse-kinematics neutron source (LICORNE) to extract charge yields of fission fragments via γ-γ coincidence spectroscopy. Experimental data and fission models are compared and found to be in reasonable agreement for many nuclei; however, significant discrepancies of up to 600% are observed, particularly for isotopes of Sn and Mo. This indicates that these models significantly overestimate the standard 1 fission mode and suggests that spherical shell effects in the nascent fissionmore » fragments are less important for low-energy fast-neutron-induced fission than for thermal neutron-induced fission. Finally, this has consequences for understanding and modeling the fission process, for experimental nuclear structure studies of the most neutron-rich nuclei, for future energy applications (e.g., Generation IV reactors which use fast-neutron spectra), and for the reactor antineutrino anomaly.« less

  16. Statistical study of auroral fragmentation into patches

    NASA Astrophysics Data System (ADS)

    Hashimoto, A.; Shiokawa, K.; Otsuka, Y.; Oyama, S. I.; Nozawa, S.; Hori, T.; Lester, M.

    2014-12-01

    Auroral complex shapes are formed through the connection of the ionosphere and magnetosphere by the geomagnetic field lines, projecting disturbances in the magnetosphere onto the ionosphere through auroral particles. Thus, the study of auroral dynamics is important for the understanding of magnetospheric disturbances. Shiokawa et al. [JGR, 2010] reported observations of small-scale finger-like auroral structures which appeared on the west side of auroral patches, at Gillam (GLAT=65.5°N), Canada, suggesting a pressure-driven plasma instability in the magnetosphere. However, statistical characteristics of this phenomenon have not been investigated yet. Using an all-sky imager at Tromsoe (MLAT=67.1°N), Norway, from January 2009 to November 2012, we made a statistical analysis of the occurrence conditions of 19 events of auroral structures that seemed to be caused by pressure-driven instability. We found 14 large-scale finger-like structures, developed from auroral arcs, and 6 small-scale finger-like structures which appeared in auroral patches. The large-scale structures were seen from midnight to dawn MLT and small-scale structures were seen mainly at dawn. Large and small-scale structures tend to appear at the beginning and late recovery phase of substorms, respectively. Their scale sizes are larger than the gyro-radius of the ions in the magnetospheric equatorial plane, indicating that the finger-like structures are caused by MHD instabilities. However, the size of the small-scale structures is roughly two times that of the gyro-radius of the ions, suggesting that the ion finite Larmor radius effects may play a role in the shape of small-scale structures [Hiraki and Sakaguchi, 2010]. Additionally, the eastward propagation speeds of the finger-like structures are slower than the typical midnight auroral drift speed, indicating that the low-energy plasma may be the source of these structures. These results could contradict the idea that the high-energy particles

  17. Frequent occurrence of T cell–mediated late reactions revealed by atopy patch testing with hypoallergenic rBet v 1 fragments

    PubMed Central

    Campana, Raffaela; Moritz, Katharina; Marth, Katharina; Neubauer, Angela; Huber, Hans; Henning, Rainer; Blatt, Katharina; Hoermann, Gregor; Brodie, Tess M.; Kaider, Alexandra; Valent, Peter; Sallusto, Federica; Wöhrl, Stefan; Valenta, Rudolf

    2015-01-01

    Background Late allergic reactions are common in the course of allergen-specific immunotherapy and even occur with allergy vaccines with reduced IgE reactivity. Objective We sought to study atopy patch test (APT) reactions and T-cell responses to the recombinant birch pollen allergen Bet v 1 and recombinant hypoallergenic T-cell epitope–containing Bet v 1 fragments in patients with birch pollen allergy with and without atopic dermatitis (AD). Methods A clinical study was conducted in 15 patients with birch pollen allergy with AD (group 1), 5 patients with birch pollen allergy without AD (group 2), 5 allergic patients without birch pollen allergy (group 3), and 5 nonallergic subjects (group 4) by performing skin prick tests and APTs with rBet v 1 and hypoallergenic rBet v 1 fragments. T-cell, cutaneous lymphocyte antigen (CLA)+ and CCR4+ T-cell and cytokine responses were studied by thymidine uptake, carboxyfluorescein diacetate succinimidyl ester staining, and Luminex technology, respectively. Results rBet v 1 and hypoallergenic rBet v 1 fragments induced APT reactions in not only most of the patients with birch pollen allergy with AD (11/15) but also in most of those without AD (4/5). Patients with birch pollen allergy with AD had higher Bet v 1–specific proliferation of CLA+ and CCR4+ T cells compared with patients with birch pollen allergy without AD. There were no differences in Bet v 1–specific CLA+ and CCR4+ proliferation and cytokine secretion in patients with and without APT reactions. Conclusion Hypoallergenic rBet v 1 fragments induce T cell–dependent late reactions not only in patients with birch pollen allergy with AD but also in those without AD, which can be determined based on APT results but not based on in vitro parameters. PMID:26518092

  18. Study of the formation of fragments with different clusterization methods

    NASA Astrophysics Data System (ADS)

    Singh, Jaivir; Puri, Rajeev K.

    2001-10-01

    We present a comparison of different clusterization methods based on simple spatial correlation, spatial-momentum correlation and energy minimization (simulated annealing) by simulating the reactions of O + Ag/Br within the quantum molecular dynamics model. We find that the response of different clusterization algorithms depends on the asymmetry of the reaction. The momentum correlation methods recognize the fragments between 60-100 fm c-1, whereas the simple spatial-correlation method needs a much longer time. The response of a larger nucleon-nucleon cross section as well as of momentum-dependent interaction depends on the clusterization algorithm one is using. It is maximal with the spatial correlation method, whereas it is minimal with the energy minimization method. Interestingly, in the presence of a larger nucleon-nucleon cross section, the momentum cut and energy minimization methods yield a similar evolution. This is true at higher incident energies where the frequency of nucleon-nucleon collisions is very large.

  19. An Experimental Study of Launch Vehicle Propellant Tank Fragmentation

    NASA Technical Reports Server (NTRS)

    Richardson, Erin; Jackson, Austin; Hays, Michael; Bangham, Mike; Blackwood, James; Skinner, Troy; Richman, Ben

    2014-01-01

    In order to better understand launch vehicle abort environments, Bangham Engineering Inc. (BEi) built a test assembly that fails sample materials (steel and aluminum plates of various alloys and thicknesses) under quasi-realistic vehicle failure conditions. Samples are exposed to pressures similar to those expected in vehicle failure scenarios and filmed at high speed to increase understanding of complex fracture mechanics. After failure, the fragments of each test sample are collected, catalogued and reconstructed for further study. Post-test analysis shows that aluminum samples consistently produce fewer fragments than steel samples of similar thickness and at similar failure pressures. Video analysis shows that there are several failure 'patterns' that can be observed for all test samples based on configuration. Fragment velocities are also measured from high speed video data. Sample thickness and material are analyzed for trends in failure pressure. Testing is also done with cryogenic and noncryogenic liquid loading on the samples. It is determined that liquid loading and cryogenic temperatures can decrease material fragmentation for sub-flight thicknesses. A method is developed for capture and collection of fragments that is greater than 97 percent effective in recovering sample mass, addressing the generation of tiny fragments. Currently, samples tested do not match actual launch vehicle propellant tank material thicknesses because of size constraints on test assembly, but test findings are used to inform the design and build of another, larger test assembly with the purpose of testing actual vehicle flight materials that include structural components such as iso-grid and friction stir welds.

  20. Molecular beam studies of reaction dynamics

    SciTech Connect

    Lee, Y.T.

    1993-12-01

    The major thrust of this research project is to elucidate detailed dynamics of simple elementary reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation.

  1. Molecular beam studies of reaction dynamics

    SciTech Connect

    Lee, Y.T.

    1990-03-01

    The major thrust of this research project is to elucidate detailed dynamics of simple reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation. 34 refs.

  2. Molecular beam studies of reaction dynamics

    SciTech Connect

    Lee, Yuan T.

    1991-03-01

    The major thrust of this research project is to elucidate detailed dynamics of simple elementary reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation.

  3. Theory of cooperative fluorescence from products of reactions or collisions: Identical neutral atomic fragments

    NASA Astrophysics Data System (ADS)

    Kurizki, Gershon; Ben-Reuven, Abraham

    1987-07-01

    The time-resolved cooperative emission from a system of correlated neutral dissociation fragments, or molecular collision products in beams, is investigated. The investigation is focused on emission at large fragment separations (between 1 nm and a few emission wavelengths), exceeding the domain of short-range interactions within the reactive or collisional molecular complex. A master-equation approach is used to obtain a general expression for the cooperative emission rate, which consists of nonexponential decay factors multiplied by temporal ringing patterns. These features result from the time-dependent radiative coupling between the receding fragments; they depend in an essential manner on the initial electronic state of the parent molecular complex and its symmetry which determine the correlations between the fragments. In the model system of a pair of identical two-level fragments two cases are considered separately. (a) A single photon shared by the fragments, where the emission is initially superradiant or subradiant (radiation trapping), depending on the spin and inversion symmetry of the parent molecular system and of the nascent fragments. The ringing pattern depends on the electronic angular momentum state of the parent molecule and on the polarization of the emitted light. (Such a ringing has been observed recently by Grangier, Aspect, and Vigué [Phys. Rev. Lett. 54, 418 (1985)] in the emission of photodissociated Ca2.) (b) Two initially excited fragments, where the ringing pattern is of smaller amplitude, and is weakly dependent on the electronic angular momentum of the parent molecule. All the aforementioned cooperative features generally last until the fragments recede several radiation wavelengths away from each other. The application of this time-resolved analysis to various diagnostic problems is discussed, especially with regard to the identification of excited electronic states of the parent molecular complex, and the stereospecificity of the

  4. Fission fragment angular distributions in the reactions {sup 16}O+{sup 188}Os and {sup 28}Si+{sup 176}Yb

    SciTech Connect

    Tripathi, R.; Sudarshan, K.; Sharma, S. K.; Reddy, A. V. R.; Pujari, P. K.; Goswami, A.; Ramachandran, K.

    2009-06-15

    Fission fragment angular distributions have been measured in the reactions {sup 16}O+{sup 188}Os and {sup 28}Si+{sup 176}Yb to investigate the contribution from noncompound nucleus fission. Parameters for statistical model calculations were fixed using fission cross section data in the {sup 16}O+{sup 188}Os reaction. Experimental anisotropies were in reasonable agreement with those calculated using the statistical saddle point model for both reactions. The present results are also consistent with those of mass distribution studies in the fission of {sup 202}Po, formed in the reactions with varying entrance channel mass asymmetry. However, the present studies do not show a large fusion hindrance as reported in the pre-actinide region based on the measurement of evaporation residue cross section.

  5. Implications of Low Volatility SOA and Gas-Phase Fragmentation Reactions on SOA Loadings and their Spatial and Temporal Evolution in the Atmosphere

    SciTech Connect

    Shrivastava, ManishKumar B.; Zelenyuk, Alla; Imre, Dan; Easter, Richard C.; Beranek, Josef; Zaveri, Rahul A.; Fast, Jerome D.

    2013-04-27

    Recent laboratory and field measurements by a number of groups show that secondary organic aerosol (SOA) evaporates orders of magnitude slower than traditional models assume. In addition, chemical transport models using volatility basis set (VBS) SOA schemes neglect gas-phase fragmentation reactions, which are known to be extremely important. In this work, we present modeling studies to investigate the implications of non-evaporating SOA and gas-phase fragmentation reactions. Using the 3-D chemical transport model, WRF-Chem, we show that previous parameterizations, which neglect fragmentation during multi-generational gas-phase chemistry of semi-volatile/inter-mediate volatility organics ("aging SIVOC"), significantly over-predict SOA as compared to aircraft measurements downwind of Mexico City. In sharp contrast, the revised models, which include gas-phase fragmentation, show much better agreement with measurements downwind of Mexico City. We also demonstrate complex differences in spatial SOA distributions when we transform SOA to non-volatile secondary organic aerosol (NVSOA) to account for experimental observations. Using a simple box model, we show that for same amount of SOA precursors, earlier models that do not employ multi-generation gas-phase chemistry of precursors ("non-aging SIVOC"), produce orders of magnitude lower SOA than "aging SIVOC" parameterizations both with and without fragmentation. In addition, traditional absorptive partitioning models predict almost complete SOA evaporation at farther downwind locations for both "non-aging SIVOC" and "aging SIVOC" with fragmentation. In contrast, in our revised approach, SOA transformed to NVSOA implies significantly higher background concentrations as it remains in particle phase even under highly dilute conditions. This work has significant implications on understanding the role of multi-generational chemistry and NVSOA formation on SOA evolution in the atmosphere.

  6. New cascarosides from Rhamnus purshiana and fragmentation studies of the class by ion trap mass spectrometry.

    PubMed

    Demarque, Daniel P; Pinho, Danielle R; Callejon, Daniel R; de Oliveira, Gibson G; Silva, Denise B; Carollo, Carlos A; Lopes, Norberto P

    2017-07-30

    Anthrone and oxanthrone are important anthraquinone derivatives present in medicinal plants which are used in therapeutics as laxatives. Some of these plants need to be stored at least one year before they can be used in order to oxidize anthrones into oxanthrones, so to avoid severe diarrhea and dehydration. Therefore, this work aimed to characterize fragmentation reactions between these anthraquinones to provide an easy way to differentiate between the two classes, since it is necessary and important to discriminate and identify these derivatives in laxative plants and phytotherapic drugs. Anthrone (cascarosides A-D) and oxanthrone (10-hydroxycascaroside A and B) derivatives were isolated and identified by NMR ((1) H, (13) C, DEPT, NOESY) and used for fragmentation study by direct infusion on an electrospray ionization (ESI) ion trap mass spectrometer (AmazonSL, Bruker) in positive and negative mode. The additional hydroxyl at C-10 in oxanthrones allowed McLafferty-type rearrangements to form the quinone group in positive mode, while in negative mode the second sugar loss infringed the odd-electron rule and formed a radical fragment. No differences in fragmentation reactions were found between diastereoisomeric pairs, although the additional oxygen at C-10 of oxanthrones allowed a different fragmentation pattern. The proposed fragmentation patterns can be used to differentiate anthrones from oxanthrones in both ion modes. In addition, they can be applied to differentiate these compounds in anthraquinone-rich plants and phytotherapic drugs. Finally, herein, the strategy applied allowed us to identify new natural products. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  7. Isospin effects on fragmentation in the asymmetric reactions induced by neutron-rich targets

    SciTech Connect

    Sharma, Arun

    2016-05-06

    To understand the isospin effects in terms of fragment’s yield in the asymmetric reactions induced by neutron-rich targets, we perform a theoretical study using isospin-dependent quantum molecular dynamics (IQMD) model. Simulations are carried out for reactions of {sup 16}O+Br{sup 80,84,92} and {sup 16}O+Ag{sup 108,113,122}. We envision that fragments’s yield in the asymmetric collisions induced by neutron-rich targets is better candidate to study isospin effects via symmetry energy and nucleon-nucleon (nn) cross-sections. Also, pronounced effects of symmetry energy and cross-sections can be found at lower and higher beam energies, respectively.

  8. Production of Neutron-Unbound States in Intermediate - Fragments from Nitrogen + Silver Reactions at E/a = 35 Mev

    NASA Astrophysics Data System (ADS)

    Heilbronn, Lawrence Harvey

    The populations of neutron-unbound states and of bound states in intermediate-mass fragments have been measured at 15^circ, 31 ^circ, and 64^circ from the ^{14}N + Ag reaction at E/A = 35 MeV. The data are identified in terms of the reaction mechanism producing them, which is either a deep-inelastic mechanism or a quasielastic mechanism. In order to test the assumption that the deep -inelastic data are produced from a thermal source, the unbound-state/bound-state population ratios of deep-inelastic fragments are compared to the predictions of a thermal sequential decay model. Most, but not all, of the deep -inelastic population ratios are fitted with model calculations that assume a source temperature between 2.5 and 3.4 MeV. Three or more populations from the same isotope were measured for ^{13}C, ^ {12}B, and ^{10} Be. The deep-inelastic populations from ^{13}C and ^{10 }Be were fitted with a single temperature, while the deep-inelastic populations from ^ {12}B were not fitted. There is enough of the deep-inelastic data that is not fitted with the predictions of a thermal model that the assumption of a thermal source for the production of deep-inelastic fragments may be incorrect, or there may be other effects present which alter the thermal properties of the data. The dependence of the unbound-state/bound-state population ratio on the fragment kinetic energy shows a difference between the quasielastic and deep-inelastic data. For quasielastic fragments whose mass is near the mass of the beam, the ratio decreases towards zero as the fragment velocity approaches the beam velocity. In contrast, the ratio for half-beam mass quasielastic fragments is constant or only slightly decreasing as the kinetic energy increases. The ratio for deep-inelastic fragments is approximately constant as a function of kinetic energy, independent of fragment mass. The amount of feeding from several neutron-unbound channels into bound states is measured and compared to the sequential

  9. Synthetic studies of enacyloxins: a series of antibiotics isolated from Frateuria sp. W-315: C1'-C8' and C9'-C15' fragments.

    PubMed

    Saito, Aki; Igarashi, Wataru; Furukawa, Hiroyuki; Hoshikawa, Hiroki; Yamada, Teiko; Kuwahara, Shigefumi; Kiyota, Hiromasa

    2015-04-01

    Synthetic studies of enacyloxins (ENXs), a series of yellow-colored, polyene-polyol antibiotics produced by Frateuria sp. W-315, are described. The C1'-C8' polyene fragments were prepared using successive Wittig reactions. The C9'-C15' and C10'-C15' fragments were constructed from (S)-isopropylideneglyceraldehyde using Yamaguchi's nucleophilic substitution reaction of acetylide to epoxide, and/or Marshall's allenylindium mediated reaction as the key steps.

  10. Transitions from functionalization to fragmentation reactions of laboratory secondary organic aerosol (SOA) generated from the OH oxidation of alkane precursors.

    PubMed

    Lambe, Andrew T; Onasch, Timothy B; Croasdale, David R; Wright, Justin P; Martin, Alexander T; Franklin, Jonathan P; Massoli, Paola; Kroll, Jesse H; Canagaratna, Manjula R; Brune, William H; Worsnop, Douglas R; Davidovits, Paul

    2012-05-15

    Functionalization (oxygen addition) and fragmentation (carbon loss) reactions governing secondary organic aerosol (SOA) formation from the OH oxidation of alkane precursors were studied in a flow reactor in the absence of NO(x). SOA precursors were n-decane (n-C10), n-pentadecane (n-C15), n-heptadecane (n-C17), tricyclo[5.2.1.0(2,6)]decane (JP-10), and vapors of diesel fuel and Southern Louisiana crude oil. Aerosol mass spectra were measured with a high-resolution time-of-flight aerosol mass spectrometer, from which normalized SOA yields, hydrogen-to-carbon (H/C) and oxygen-to-carbon (O/C) ratios, and C(x)H(y)+, C(x)H(y)O+, and C(x)H(y)O(2)+ ion abundances were extracted as a function of OH exposure. Normalized SOA yield curves exhibited an increase followed by a decrease as a function of OH exposure, with maximum yields at O/C ratios ranging from 0.29 to 0.74. The decrease in SOA yield correlates with an increase in oxygen content and decrease in carbon content, consistent with transitions from functionalization to fragmentation. For a subset of alkane precursors (n-C10, n-C15, and JP-10), maximum SOA yields were estimated to be 0.39, 0.69, and 1.1. In addition, maximum SOA yields correspond with a maximum in the C(x)H(y)O+ relative abundance. Measured correlations between OH exposure, O/C ratio, and H/C ratio may enable identification of alkane precursor contributions to ambient SOA.

  11. Mechanisms and kinetics of noncatalytic ether reaction in supercritical water. 2. Proton-transferred fragmentation of dimethyl ether to formaldehyde in competition with hydrolysis.

    PubMed

    Nagai, Yasuharu; Matubayasi, Nobuyuki; Nakahara, Masaru

    2005-04-28

    Noncatalytic reaction pathways and rates of dimethyl ether (DME) in supercritical water are determined in a tube reactor made of quartz according to liquid- and gas-phase 1H and 13C NMR observations. The reaction is studied at two concentrations (0.1 and 0.5 M) in supercritical water at 400 degrees C and over a water-density range of 0.1-0.6 g/cm3. The supercritical water reaction is compared with the neat one (in the absence of solvent) at 0.1 M and 400 degrees C. DME is found to decompose through (i) the proton-transferred fragmentation to methane and formaldehyde and (ii) the hydrolysis to methanol. Formaldehyde from reaction (i) is consecutively subjected to four types of redox reactions. Two of them proceed even without solvent: (iii) the unimolecular proton-transferred decarbonylation forming hydrogen and carbon monoxide and (iv) the bimolecular self-disproportionation generating methanol and carbon monoxide. When the solvent water is present, two additional paths are open: (v) the bimolecular self-disproportionation of formaldehyde with reactant water, producing methanol and formic acid, and (vi) the bimolecular cross-disproportionation between formaldehyde and formic acid, yielding methanol and carbonic acid. Methanol is produced through the three types of disproportionations (iv)-(vi) as well as the hydrolysis (ii). The presence of solvent water decelerates the proton-transferred fragmentation of DME; the rate constant is reduced by 40% at 0.5 g/cm3. This is caused by the suppression of low-frequency concerted motion corresponding to the reaction coordinate for the simultaneous C-O bond scission and proton transfer from one methyl carbon to the other. In contrast to the proton-transferred fragmentation, the hydrolysis of DME is markedly accelerated by increasing the water density. The latter becomes more important than the former in supercritical water at densities greater than 0.5 g/cm3.

  12. DEATH-STAR: Silicon and photovoltaic fission fragment detector arrays for light-ion induced fission correlation studies

    DOE PAGES

    Koglin, J. D.; Burke, J. T.; Fisher, S. E.; ...

    2017-02-20

    Here, the Direct Excitation Angular Tracking pHotovoltaic-Silicon Telescope ARray (DEATH-STAR) combines a series of 12 silicon detectors in a ΔE–E configuration for charged particle identification with a large-area array of 56 photovoltaic (solar) cells for detection of fission fragments. The combination of many scattering angles and fission fragment detectors allows for an angular-resolved tool to study reaction cross sections using the surrogate method, anisotropic fission distributions, and angular momentum transfers through stripping, transfer, inelastic scattering, and other direct nuclear reactions. The unique photovoltaic detectors efficiently detect fission fragments while being insensitive to light ions and have a timing resolution ofmore » 15.63±0.37 ns. Alpha particles are detected with a resolution of 35.5 keV 1σ at 7.9 MeV. Measured fission fragment angular distributions are also presented.« less

  13. DEATH-STAR: Silicon and Photovoltaic Fission Fragment Detector Arrays for Light-Ion Induced Fission Correlation Studies

    NASA Astrophysics Data System (ADS)

    Koglin, J. D.; Burke, J. T.; Fisher, S. E.; Jovanovic, I.

    2017-05-01

    The Direct Excitation Angular Tracking pHotovoltaic-Silicon Telescope ARray (DEATH-STAR) combines a series of 12 silicon detectors in a ΔE - E configuration for charged particle identification with a large-area array of 56 photovoltaic (solar) cells for detection of fission fragments. The combination of many scattering angles and fission fragment detectors allows for an angular-resolved tool to study reaction cross sections using the surrogate method, anisotropic fission distributions, and angular momentum transfers through stripping, transfer, inelastic scattering, and other direct nuclear reactions. The unique photovoltaic detectors efficiently detect fission fragments while being insensitive to light ions and have a timing resolution of 15.63±0.37 ns. Alpha particles are detected with a resolution of 35.5 keV 1σ at 7.9 MeV. Measured fission fragment angular distributions are also presented.

  14. DNA fragmentation of human sperm can be detected by ligation-mediated real-time polymerase chain reaction.

    PubMed

    Lim, Jung Jin; Lee, Jin Il; Kim, Dong Hwan; Song, Seung-Hun; Kim, Hyung Joon; Lee, Woo Sik; Lee, Dong Ryul

    2013-12-01

    To determine whether ligation-mediated real-time polymerase chain reaction (LM-RT-PCR), which combines LM-PCR, and RT-PCR, can detect sperm DNA fragmentation (DF) in human semen samples. Three-way comparison of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), sperm chromatin dispersion (SCD), and LM-RT-PCR for detecting sperm DNA fragmentation. University hospital-based research laboratory. Twenty-five men presenting at an infertility clinic. Basic analysis of sperm concentration, motility, vitality, and morphology, with each semen sample equally divided into three aliquots that were evaluated for fragmentation using TUNEL, SCD, and LM-RT-PCR assays. In TUNEL and SCD assays, counts of the number of sperm with tetramethylrhodamine (TMR) red signals or no halo; in LM-RT-PCR results, evaluation of the threshold cycles (Ct) and relative fluorescence unit (RFU) values. The median percentage of sperm with positive results for fragmentation in the TUNEL and SCD assays were 20.5% and 20.7%, respectively. To compare the accuracy of the TUNEL, SCD, and LM-RT-PCR assays, we divided the semen samples into two groups according to the TUNEL results: low and high percentage of sperm fragmentation. In the LM-RT-PCR results, the values of the cycles of threshold (Ct) and relative fluorescence unit (RFU) statistically significantly differed between the low and high percentage of sperm fragmentation groups. Comparisons among the TUNEL, SCD, and LM-RT-PCR assays revealed that the correlation patterns according to DNA fragmentation were similar in both the groups with high and low percentage of DNA fragmentation. Our morphologic analysis indicated that the fragmentation of sperm DNA did not appear to influence sperm morphology. These results indicate that the LM-RT-PCR technique is another useful tool for detecting DNA fragmentation, a parameter of sperm quality in human semen alone or combined with TUNEL or SCD assays. Copyright © 2013 American Society for

  15. Excitations of atomic fragments arising in the exothermic (n;q) reactions of light atoms with slow neutrons.

    PubMed

    Frolov, Alexei M; Wardlaw, David M

    2007-12-21

    We have developed the closed procedure for evaluating the final state probabilities in atomic fragments which arise during exothermic (n;t)-, (n;alpha)-, and (n;p)-nuclear reactions in some light atoms with slow neutrons. The procedure includes the two consecutive steps: (1) computation of the final state probabilities based on the sudden approximation and (2) evaluation of various transition probabilities between the states obtained at the first step.

  16. Activity-Directed Synthesis with Intermolecular Reactions: Development of a Fragment into a Range of Androgen Receptor Agonists

    PubMed Central

    Karageorgis, George; Dow, Mark; Aimon, Anthony; Warriner, Stuart; Nelson, Adam

    2015-01-01

    Activity-directed synthesis (ADS), a novel discovery approach in which bioactive molecules emerge in parallel with associated syntheses, was exploited to develop a weakly binding fragment into novel androgen receptor agonists. Harnessing promiscuous intermolecular reactions of carbenoid compounds enabled highly efficient exploration of chemical space. Four substrates were prepared, yet exploited in 326 reactions to explore diverse chemical space; guided by bioactivity alone, the products of just nine of the reactions were purified to reveal diverse novel agonists with up to 125-fold improved activity. Remarkably, one agonist stemmed from a novel enantioselective transformation; this is the first time that an asymmetric reaction has been discovered solely on the basis of the biological activity of the product. It was shown that ADS is a significant addition to the lead generation toolkit, enabling the efficient and rapid discovery of novel, yet synthetically accessible, bioactive chemotypes. PMID:26358926

  17. The Zero-Degree Detector System for Fragmentation Studies

    NASA Technical Reports Server (NTRS)

    Adams, J. H., Jr.; Christl, M. J.; Howell, L. W.; Kuznetsov, E.

    2006-01-01

    The measurement of nuclear fragmentation cross sections requires the detection and identification of individual projectile fragments. If light and heavy fragments are recorded in 'ne same detector, it may be impossible distinguish the signal from the light fragment. To overcome this problem, we have developed the Zero-Degree Detector System. The ZDDS enables the measurement of cross sections for light fragment production by using pixelated detectors to separately measure the signals of each fragment. The system has been used to measure the fragmentation of beams as heavy as Fe at the NASA Space Radiation Laboratory at Brookhaven National Laboratory and the Heavy Ion Medical Accelerator in Chiba, Japan.

  18. Theoretical Studies of Reaction Surfaces

    DTIC Science & Technology

    2007-11-02

    31 Aug 97 4. TITLE AND SUBTITLE 5 . FUNDING NUMBERS AASERT93 THEORETICAL STUDIES OF REACTION SURFACES F49620-93-1-0556 3484/XS 6. AUTHOR(S) 61103D DR...DUNCAN AVE ROOM B115 BOLLING AFB DC 20332- 8050 DR MICHAEL R. BERMAN 11. SUPPLEMENTARY NOTES 12a. DISTRIBUTION i AVAILABILITY STATEMENT Approved f or pill...reaction14 , and solvation of electrolytes1 5 . The EFP method described in the previous section has one drawback: the repulsive 3 potential relies on

  19. Polymerase chain reaction-restriction fragment-length polymorphism method to distinguish Liriomyza huidobrensis from L. Langei (Diptera: Agromyzidae) applied to three recent leafminer invasions.

    PubMed

    Scheffer, S J; Wijesekara, A; Visser, D; Hallett, R H

    2001-10-01

    A molecular method is presented for differentiating the morphologically cryptic leafminers Liriomyza langei Frick and L. huidobrensis (Blanchard). This method requires polymerase chain reaction (PCR) amplification of a 1031-bp region of mitochondrial cytochrome oxidase DNA followed by restriction fragment analysis using the restriction enzymes SpeI and EcoRV. Spel cuts the mitochondrial fragment of L. langei into two fragments, but does not cut the L. huidobrensis fragment. EcoRV cuts the L. huidobrensis fragment into two fragments, but does not cut the L. langei fragment. This PCR-restriction fragment-length polymorphism (RFLP) method is faster and less costly than DNA sequencing,which is currently the only other way to differentiate these two species. We apply the method to samples from recently introduced leafminer populations in Sri Lanka, Canada, and South Africa and find that the invasive leafminer in all three locations is L. huidobrensis.

  20. Limits of a rapid identification of common Mediterranean sandflies using polymerase chain reaction-restriction fragment length polymorphism

    PubMed Central

    Bounamous, Azzedine; Lehrter, Véronique; Hadj-Henni, Leila; Delecolle, Jean-Claude; Depaquit, Jérôme

    2014-01-01

    A total of 131 phlebotomine Algerian sandflies have been processed in the present study. They belong to the species Phlebotomus bergeroti, Phlebotomus alexandri, Phlebotomus sergenti, Phlebotomus chabaudi, Phlebotomus riouxi, Phlebotomus perniciosus, Phlebotomus longicuspis, Phlebotomus perfiliewi, Phlebotomus ariasi, Phlebotomus chadlii, Sergentomyia fallax, Sergentomyia minuta, Sergentomyia antennata, Sergentomyia schwetzi, Sergentomyia clydei, Sergentomyia christophersi and Grassomyia dreyfussi. They have been characterised by sequencing of a part of the cytochrome b (cyt b), t RNA serine and NADH1 on the one hand and of the cytochrome C oxidase I of the mitochondrial DNA (mtDNA) on the other hand. Our study highlights two sympatric populations within P. sergenti in the area of its type-locality and new haplotypes of P. perniciosus and P. longicuspis without recording the specimens called lcx previously found in North Africa. We tried to use a polymerase chain reaction-restriction fragment length polymorphism method based on a combined double digestion of each marker. These method is not interesting to identify sandflies all over the Mediterranean Basin. PMID:24936911

  1. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for rapid diagnosis of neonatal sepsis.

    PubMed

    Rohit, Anusha; Maiti, Biswajit; Shenoy, Shalini; Karunasagar, Indrani

    2016-01-01

    The difficulties in diagnosis of neonatal sepsis are due to varied clinical presentation, low sensitivity of blood culture which is considered the gold standard and empirical antibiotic usage affecting the outcome of results. Though polymerase chain reaction (PCR) based detection of bacterial 16S rRNA gene has been reported earlier, this does not provide identification of the causative agent. In this study, we used restriction fragment length polymorphism (RFLP) of amplified 16S rRNA gene to identify the organisms involved in neonatal sepsis and compared the findings with blood culture. Blood samples from 97 neonates were evaluated for diagnosis of neonatal sepsis using BacT/Alert (automated blood culture) and PCR-RFLP. Bacterial DNA was detected by 16S rRNA gene PCR in 55 cases, while BacT/Alert culture was positive in 34 cases. Staphylococcus aureus was the most common organism detected with both methods. Klebsiella spp. was isolated from four samples by culture but was detected by PCR-RFLP in five cases while Acinetobacter spp. was isolated from one case but detected in eight cases by PCR-RFLP. The sensitivity of PCR was found to be 82.3 per cent with a negative predictive value of 85.7 per cent. Eighty of the 97 neonates had prior exposure to antibiotics. The results of our study demonstrate that PCR-RFLP having a rapid turnaround time may be useful for the early diagnosis of culture negative neonatal sepsis.

  2. Luciferase fragment complementation imaging in preclinical cancer studies

    PubMed Central

    Lake, Madryn C.; Aboagye, Eric O.

    2014-01-01

    The luciferase fragment complementation assay (LFCA) enables molecular events to be non-invasively imaged in live cells in vitro and in vivo in a comparatively cheap and safe manner. It is a development of previous enzyme complementation assays in which reporter genes are split into two, individually enzymatically inactive, fragments that are able to complement one another upon interaction. This complementation can be used to externally visualize cellular activities. In recent years, the number of studies which have used LFCAs to probe questions relevant to cancer have increased, and this review summarizes the most significant and interesting of these. In particular, it focuses on work conducted on the epidermal growth factor, nuclear and chemokine receptor families, and intracellular signaling pathways, including IP3, cAMP, Akt, cMyc, NRF2 and Rho GTPases. LFCAs which have been developed to image DNA methylation and detect RNA transcripts are also discussed. PMID:25594026

  3. Spectroscopy of exotic 123,125Ag produced in fragmentation reactions

    NASA Astrophysics Data System (ADS)

    Stefanescu, I.; Walters, W. B.; Hoteling, N.; Tomlin, B.; Mantica, P. F.; Pereira, J.; Becerril, A.; Fleckenstein, T.; Hecht, A. A.; Lorusso, G.; Quinn, M.; Pinter, J. S.; Stoker, J. B.

    2008-04-01

    We extended the experimental knowledge in the mass-region around 132Sn by identifying the decay of high-spin isomers in the exotic odd-mass 123,125Ag. The two isotopes were produced at the NSCL laboratory by projectile fragmentation of a 136Xe beam at 120MeV/u directed onto a thick Be target. The NSCL Beta Counting System, was used identify secondary beam fragments. Prompt and delayed gamma-rays following the deexcitation of the fragments were detected with the SEGA array. Partial level schemes for 123,125Ag are proposed for the first time. The observed states show single-particle characteristics, indicating strong Z=50 and N=82 shell gaps and also support the proposed weakened nucleon-nucleon interaction in this mass-region.

  4. Wavefront reconstruction with pupil fragmentation: study of a simple case

    NASA Astrophysics Data System (ADS)

    Bonnefond, Sylvain; Tallon, Michel; Le Louarn, Miska; Madec, Pierre-Yves

    2016-07-01

    The use of smaller subapertures on some recent adaptive optics (AO) systems seems to yield difficulties in wavefront reconstruction, known as spider effect or pupil fragmentation: the size of the subapertures is small enough so that some of them are masked by the telescope spider, dividing the pupil into disconnected domains. In particular, this problem will arise on the E-ELT.We have studied pure wavefront reconstruction on a Shack-Hartmann wavefront sensor, for a simplified AO system similar to VLT/SPHERE in size, with and without pupil fragmentation, and compared the performance of various wavefront reconstructors for different signal-to-noise ratios, using priors (minimum variance) or not (least-squares), and with different assumptions for the damaged wavefront measurements. The missing measurements have been either discarded (corresponding subapertures are not active), replaced by zeros, or interpolated by preserving the loop continuity property of the gradients (curl operator). Priors have been introduced using the FrIM (Fractal Iterative Method) algorithm. In our perfect conditions, we show that no method allows the full recovery from the pupil fragmentation, that minimum variance always gives the best performance, especially the one without any interpolation. On the opposite, the performance with least-squares somewhat improves when correcting for the missing measurements. In this latter case, preserving the curl property of the gradient is preferable only for very low measurement noise.

  5. Molecular Epidemiology of Leptospirosis in Northern Iran by Nested Polymerase Chain Reaction/Restriction Fragment Length Polymorphism and Sequencing Methods

    PubMed Central

    Zakeri, Sedigheh; Sepahian, Neda; Afsharpad, Mandana; Esfandiari, Behzad; Ziapour, Peyman; Djadid, Navid D.

    2010-01-01

    This study was conducted to investigate the prevalence of Leptospira species in Mazandaran Province of Iran by using nested polymerase chain reaction (PCR)/restriction fragment length polymorphism (RFLP) methods and sequencing analysis. Blood samples (n = 119) were collected from humans suspected of having leptospirosis from different parts of the province in 2007. By using an indirect immunofluorescent antibody test (IFAT), we determined that 35 (29.4%) of 119 suspected cases had leptospiral antibody titers ≥ 1:80, which confirmed the diagnosis of leptospirosis. Nested PCR assay also determined that 60 (50.4%) of 119 samples showed Leptospira infection. Furthermore, 44 (73.3%) of 60 confirmed leptospirosis amplified products were subjected to sequencing analysis. Sequence alignment identified L. interrogans, L. kirschneri, and L. wolffii species. All positive cases diagnosed by IFAT or PCR were in patients who reported contact with animals, high-risk occupational activities, and exposure to contaminated water. Therefore, it is important to increase attention about this disease among physicians and to strengthen laboratory capacity for its diagnosis in infected patients in Iran. PMID:20439973

  6. Measurement and verification of positron emitter nuclei generated at each treatment site by target nuclear fragment reactions in proton therapy

    SciTech Connect

    Miyatake, Aya; Nishio, Teiji; Ogino, Takashi; Saijo, Nagahiro; Esumi, Hiroyasu; Uesaka, Mitsuru

    2010-08-15

    Purpose: The purpose of this study is to verify the characteristics of the positron emitter nuclei generated at each treatment site by proton irradiation. Methods: Proton therapy using a beam on-line PET system mounted on a rotating gantry port (BOLPs-RGp), which the authors developed, is provided at the National Cancer Center Kashiwa, Japan. BOLPs-RGp is a monitoring system that can confirm the activity distribution of the proton irradiated volume by detection of a pair of annihilation gamma rays coincidentally from positron emitter nuclei generated by the target nuclear fragment reactions between irradiated proton nuclei and nuclei in the human body. Activity is measured from a start of proton irradiation to a period of 200 s after the end of the irradiation. The characteristics of the positron emitter nuclei generated in a patient's body were verified by the measurement of the activity distribution at each treatment site using BOLPs-RGp. Results: The decay curves for measured activity were able to be approximated using two or three half-life values regardless of the treatment site. The activity of half-life value of about 2 min was important for a confirmation of the proton irradiated volume. Conclusions: In each proton treatment site, verification of the characteristics of the generated positron emitter nuclei was performed by using BOLPs-RGp. For the monitoring of the proton irradiated volume, the detection of {sup 15}O generated in a human body was important.

  7. Polymerase chain reaction-restriction fragment length polymorphism analysis: a simple method for species identification in food.

    PubMed

    Meyer, R; Höfelein, C; Lüthy, J; Candrian, U

    1995-01-01

    The polymerase chain reaction (PCR) technique was applied to meat species identification in marinated and heat-treated or fermented products and to the differentiation of closely related species. DNA was isolated from meat samples by using a DNA-binding resin and was subjected to PCR analysis. Primers used were complementary to conserved areas of the vertebrate mitochondrial cytochrome b (cytb) gene and yielded a 359 base-pair (bp) fragment, including a variable 307 bp region. Restriction endonuclease analysis based on sequence data of those fragments was used for differentiation among species. Restriction fragment length polymorphisms (RFLPs) were detected when pig, cattle, wild boar, buffalo, sheep, goat, horse, chicken, and turkey amplicons were cut with AluI, RsaI, TaqI, and HinfI. Analysis of sausages indicates the applicability of this approach to food products containing meat from 3 different species. The PCR-RFLP analytical method detected pork in heated meat mixtures with beef at levels below 1%, and the method was confirmed with porcine- and bovine-specific PCR assays by amplifying fragments of their growth hormone genes. Inter- and intraspecific differences of more than 22 animal species with nearly unknown cytb DNA sequences, including hoofed mammals (ungulates), and poultry were determined with PCR-RFLP typing by using 20 different endonucleases. This typing method allowed the discrimination of game meats, including stag, roe deer, chamois, moose, reindeer, kangaroo, springbok, and other antelopes in marinated and heat-treated products.

  8. Studies of complex fragment emission in heavy ion reactions

    SciTech Connect

    Charity, R.J.; Sobotka, L.G.

    1991-09-04

    This report discusses the following topics: High energy photon production in a HI collision; the mechanism for the disassembly of excited {sup 16}O projectiles into four alpha particles; the disassembly of excited {sup 28}Si projectiles; large pre-fission multiplicities from temperature; dependent friction and fission barriers; multiplicity correlations; molecular beam induced fusion; dwarf ball and wall; mini wall; and computer and local data acquisition systems.

  9. Native-state hydrogen-exchange studies of a fragment complex can provide structural information about the isolated fragments

    PubMed Central

    Chakshusmathi, G.; Ratnaparkhi, Girish S.; Madhu, P. K.; Varadarajan, R.

    1999-01-01

    Ordered protein complexes are often formed from partially ordered fragments that are difficult to structurally characterize by conventional NMR and crystallographic techniques. We show that concentration-dependent hydrogen exchange studies of a fragment complex can provide structural information about the solution structures of the isolated fragments. This general methodology can be applied to any bimolecular or multimeric system. The experimental system used here consists of Ribonuclease S, a complex of two fragments of Ribonuclease A. Ribonuclease S and Ribonuclease A have identical three-dimensional structures but exhibit significant differences in their dynamics and stability. We show that the apparent large dynamic differences between Ribonuclease A and Ribonuclease S are caused by small amounts of free fragments in equilibrium with the folded complex, and that amide exchange rates in Ribonuclease S can be used to determine corresponding rates in the isolated fragments. The studies suggest that folded RNase A and the RNase S complex exhibit very similar dynamic behavior. Thus cleavage of a protein chain at a single site need not be accompanied by a large increase in flexibility of the complex relative to that of the uncleaved protein. PMID:10393919

  10. Interfacial Reaction Studies Using ONIOM

    NASA Technical Reports Server (NTRS)

    Cardelino, Beatriz H.

    2003-01-01

    In this report, we focus on the calculations of the energetics and chemical kinetics of heterogeneous reactions for Organometallic vapor phase epitaxy (OMVPE). The work described in this report builds upon our own previous thermochemical and chemical kinetics studies. The first of these articles refers to the prediction of thermochemical properties, and the latter one deals with the prediction of rate constants for gaseous homolytic dissociation reactions. The calculations of this investigation are at the microscopic level. The systems chosen consisted of a gallium nitride (GaN) substrate, and molecular nitrogen (N2) and ammonia (NH3) as adsorbants. The energetics for the adsorption and the adsorbant dissociation processes were estimated, and reaction rate constants for the dissociation reactions of free and adsorbed molecules were predicted. The energetics for substrate decomposition was also computed. The ONIOM method, implemented in the Gaussian98 program, was used to perform the calculations. This approach has been selected since it allows dividing the system into two layers that can be treated at different levels of accuracy. The atoms of the substrate were modeled using molecular mechanics6 with universal force fields, whereas the adsorbed molecules were approximated using quantum mechanics, based on density functional theory methods with B3LYP functionals and 6-311G(d,p) basis sets. Calculations for the substrate were performed in slabs of several unit cells in each direction. The N2 and NH3 adsorbates were attached to a central location at the Ga-lined surface.

  11. Identification of blood meal sources of Lutzomyia longipalpis using polymerase chain reaction-restriction fragment length polymorphism analysis of the cytochrome B gene.

    PubMed

    Soares, Vítor Yamashiro Rocha; Silva, Jailthon Carlos da; Silva, Kleverton Ribeiro da; Pires e Cruz, Maria do Socorro; Santos, Marcos Pérsio Dantas; Ribolla, Paulo Eduardo Martins; Alonso, Diego Peres; Coelho, Luiz Felipe Leomil; Costa, Dorcas Lamounier; Costa, Carlos Henrique Nery

    2014-06-01

    An analysis of the dietary content of haematophagous insects can provide important information about the transmission networks of certain zoonoses. The present study evaluated the potential of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the mitochondrial cytochrome B (cytb) gene to differentiate between vertebrate species that were identified as possible sources of sandfly meals. The complete cytb gene sequences of 11 vertebrate species available in the National Center for Biotechnology Information database were digested with Aci I, Alu I, Hae III and Rsa I restriction enzymes in silico using Restriction Mapper software. The cytb gene fragment (358 bp) was amplified from tissue samples of vertebrate species and the dietary contents of sandflies and digested with restriction enzymes. Vertebrate species presented a restriction fragment profile that differed from that of other species, with the exception of Canis familiaris and Cerdocyon thous. The 358 bp fragment was identified in 76 sandflies. Of these, 10 were evaluated using the restriction enzymes and the food sources were predicted for four: Homo sapiens (1), Bos taurus (1) and Equus caballus (2). Thus, the PCR-RFLP technique could be a potential method for identifying the food sources of arthropods. However, some points must be clarified regarding the applicability of the method, such as the extent of DNA degradation through intestinal digestion, the potential for multiple sources of blood meals and the need for greater knowledge regarding intraspecific variations in mtDNA.

  12. Identification of blood meal sources of Lutzomyia longipalpis using polymerase chain reaction-restriction fragment length polymorphism analysis of the cytochrome B gene

    PubMed Central

    Soares, Vítor Yamashiro Rocha; da Silva, Jailthon Carlos; da Silva, Kleverton Ribeiro; Cruz, Maria do Socorro Pires e; Santos, Marcos Pérsio Dantas; Ribolla, Paulo Eduardo Martins; Alonso, Diego Peres; Coelho, Luiz Felipe Leomil; Costa, Dorcas Lamounier; Costa, Carlos Henrique Nery

    2014-01-01

    An analysis of the dietary content of haematophagous insects can provide important information about the transmission networks of certain zoonoses. The present study evaluated the potential of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the mitochondrial cytochrome B (cytb) gene to differentiate between vertebrate species that were identified as possible sources of sandfly meals. The complete cytb gene sequences of 11 vertebrate species available in the National Center for Biotechnology Information database were digested with Aci I, Alu I, Hae III and Rsa I restriction enzymes in silico using Restriction Mapper software. The cytb gene fragment (358 bp) was amplified from tissue samples of vertebrate species and the dietary contents of sandflies and digested with restriction enzymes. Vertebrate species presented a restriction fragment profile that differed from that of other species, with the exception of Canis familiaris and Cerdocyon thous. The 358 bp fragment was identified in 76 sandflies. Of these, 10 were evaluated using the restriction enzymes and the food sources were predicted for four: Homo sapiens (1), Bos taurus (1) and Equus caballus (2). Thus, the PCR-RFLP technique could be a potential method for identifying the food sources of arthropods. However, some points must be clarified regarding the applicability of the method, such as the extent of DNA degradation through intestinal digestion, the potential for multiple sources of blood meals and the need for greater knowledge regarding intraspecific variations in mtDNA. PMID:24821056

  13. Development of white blood cell fragments, during the preparation and storage of platelet concentrates, as measured by using real-time polymerase chain reaction.

    PubMed

    Dijkstra-Tiekstra, M J; van der Schoot, C E; Pietersz, R N I; Huijgens, P C; van der Meer, P F; Reesink, H W

    2004-11-01

    White blood cell (WBC) fragments may cause human leucocyte antigen (HLA) immunization in recipients. We investigated the occurrence and production of WBC fragments in platelet concentrates (PCs) and plasma units, during storage and filtration, by using real-time polymerase chain reaction (PCR) and flow cytometry. To study the occurrence of WBC fragments, 'male' WBCs were spiked into double-filtered 'female' PCs in a concentration series of 0.03-100 WBCs/microl (n = 4 per level). To study the production of WBC fragments, 'male' WBCs were spiked into 'female' plasma units to 4 x 10(9) WBCs/l and stored at room temperature prior to filtration (n = 4 per storage time; t = 0, 24 or 48 h). DNA was measured by both albumin real-time PCR and Y real-time PCR. Intact WBCs were counted by using flow cytometry. The number of WBC fragments was calculated by subtracting cell-free DNA (real-time PCR on supernatant) and intact WBCs (flow cytometry) from the total DNA amount (real-time PCR). Spiking of 'male' WBCs into 'female' PCs showed that the Y real-time PCR is linear and has a reproducible quantitative range down to 0.03 WBC/microl, but that the albumin-PCR, in unspiked samples, revealed a total of 6-10 WBC equivalents/microl (eq/microl). After centrifugation, half of this was observed as cell-free DNA in the supernatant, suggesting that the remaining DNA is derived from WBC fragments. The number of intact WBCs, amount of cell-free DNA and number of WBC fragments after filtration increased significantly when filtration was delayed for up to 48 h, from 0.1 WBC/microl, 1.3 WBC eq/microl and 0.6 WBC eq/microl at t = 0 h to 25 WBC/microl, 38 WBC eq/microl and 57 WBC eq/microl at t = 48 h, respectively. WBC fragments occur in WBC-reduced PCs and increase when products are stored, prior to filtration, up to levels that are equivalent to the amounts of intact WBCs that induce HLA immunization (i.e. > 5 x 10(6)/unit).

  14. Mechanistic diversity in thermal fragmentation reactions: a computational exploration of CO and CO₂ extrusions from five-membered rings.

    PubMed

    Rzepa, Henry S; Wentrup, Curt

    2013-08-02

    The mechanisms of a variety of thermal pericyclic fragmentation reactions of five-membered heterocyclic rings are subjected to scrutiny at a density functional level by computation of transition state free energy barriers and intrinsic reaction coordinates (IRCs). The preferred computed products generally match those observed in flash vacuum thermolysis experiments. For certain reactions, which also have the highest reaction temperatures and computed barriers, a degree of multireference character to the wave function manifests in an overestimation of the DFT-computed barrier, with a more reasonable barrier obtained by a CASSCF single point energy calculation. Many of the IRCs exhibit "hidden intermediates" along the reaction pathway, but conversely reactions that could be considered to involve the formation of an intermediate nitrene prior to alkyl or aryl migration show no evidence of such an intermediate. Such exploration of the diversity of behavior in a class of compounds using computational methods with interactive presentation of the results within the body of a journal article is suggested as being almost a sine qua non for laboratory-based research on reactive intermediates.

  15. (Laser enhanced chemical reaction studies)

    SciTech Connect

    Not Available

    1992-01-01

    Experimental studies of dynamic molecular processes are described with particular emphasis on the use of a powerful infrared diode laser probe technique developed in our laboratory. This technique allows us to determine the final states of CO{sub 2} (and other molecules) produced by collisions, photofragmentation, or chemical reactions with a spectral resolution of 0.0003 cm{sup {minus}1} and a time resolution of 10{sup {minus}7} sec. Such high spectral resolution provides a detailed picture of the vibrational and rotational states of molecules produced by these dynamic events. We have used this experimental method to probe collisions between hot hydrogen/deuterium atoms and CO{sub 2}, between O({sup 1}D) atoms and CO{sub 2}, to study the final states of DC1 molecules produced as a result of the reactions of hot Cl atoms, and to investigate the dynamics of the reaction between OH and CO molecules. Advances in our techniques over the past two years have allowed us to identify and study more than 200 final rotational states in ten different vibrational levels of CO{sub 2} encompassing all 3 normal modes, many overtones, and combination states of the molecule. We have extended the technique to probe a variety of new molecules such as OCS, N{sub 2}O, DCl, and CS{sub 2}. All of this work is aimed at providing experimental tests for polyatomic molecule potential energy surfaces, chemical transition states in complex systems, and theories of reaction dynamic in molecules with more than 3 atoms.

  16. Folding angle and excitation energy of fragments from 235U(n th,f) and 252Cf(sf) reactions

    NASA Astrophysics Data System (ADS)

    Haninger, T.; Hartmann, F. J.; Hofmann, P.; Kim, Y. S.; Lotfranaei, M. S.; von Egidy, T.; Märten, H.; Ruben, A.

    1994-05-01

    Coincident fragments from 235U(n th,f) and 252Cf(sf) reactions were investigated with a doublearm fission-fragment spectrometer and PIN-diode arrays. Based on the measurement of kinetic energy, velocity and direction of complementary fragments the total kinetic energy, the total mass, the individual fragment masses, the total number of emitted neutrons as well as the folding angle were deduced event by event. A nearly linear correlation between average folding angle and average total excitation energy of the fragments (and, consequently, the average number of neutrons) was found. Fragment deflection by prompt neutron emission is accordingly described by a complex statistical evaporation model in connection with a semi-empirical calculation of energy partition in nuclear fission. In addition, the folding-angle distribution due to ternary fission is estimated. All experimental fragment distributions and correlations are well repro- duced by the model calculations.

  17. Intraocular Lens Fragmentation Using Femtosecond Laser: An In Vitro Study

    PubMed Central

    Bala, Chandra; Shi, Jeffrey; Meades, Kerrie

    2015-01-01

    Purpose: To transect intraocular lenses (IOLs) using a femtosecond laser in cadaveric human eyes. To determine the optimal in vitro settings, to detect and characterize gasses or particles generated during this process. Methods: A femtosecond laser was used to transect hydrophobic and hydrophilic acrylic lenses. The settings required to enable easy separation of the lens fragment were determined. The gasses and particles generated were analysed using gas chromatography mass spectrometer (GC-MS) and total organic carbon analyzer (TOC), respectively. Results: In vitro the IOL fragments easily separated at the lowest commercially available energy setting of 1 μJ, 8-μm spot, and 2-μm line separation. No particles were detected in the 0.5- to 900-μm range. No significant gasses or other organic breakdown by products were detected at this setting. At much higher energy levels 12 μJ (4 × 6 μm spot and line separation) significant pyrolytic products were detected, which could be harmful to the eye. In cadaveric explanted IOL capsule complex the laser pulses could be applied through the capsule to the IOL and successfully fragment the IOL. Conclusion: IOL transection is feasible with femtosecond lasers. Further in vivo animal studies are required to confirm safety. Translational Relevance: In clinical practice there are a number of large intraocular lenses that can be difficult to explant. This in-vitro study examines the possibility of transecting the lasers quickly using femtosecond lasers. If in-vivo studies are successful, then this innovation could help ophthalmic surgeons in IOL explantation. PMID:26101721

  18. Recent Direct Reaction Experimental Studies with Radioactive Tin Beams

    DOE PAGES

    Jones, K. L.; Ahn, S.; Allmond, J. M.; ...

    2015-01-01

    Direct reaction techniques are powerful tools to study the single-particle nature of nuclei. Performing direct reactions on short-lived nuclei requires radioactive ion beams produced either via fragmentation or the Isotope Separation OnLine (ISOL) method. Some of the most interesting regions to study with direct reactions are close to the magic numbers where changes in shell structure can be tracked. These changes can impact the final abundances of explosive nucleosynthesis. The structure of the chain of tin isotopes is strongly influenced by the Z = 50 proton shell closure, as well as the neutron shell closures lying in the neutron-rich, Nmore » = 82, and neutron-deficient, N = 50, regions. Here, we present two examples of direct reactions on exotic tin isotopes. The first uses a one-neutron transfer reaction and a low-energy reaccelerated ISOL beam to study states in Sn-131 from across the N = 82 shell closure. The second example utilizes a one-neutron knockout reaction on fragmentation beams of neutron-deficient Sn-106,108Sn. In conclusion, In both cases, measurements of γ rays in coincidence with charged particles proved to be invaluable.« less

  19. Recent Direct Reaction Experimental Studies with Radioactive Tin Beams

    SciTech Connect

    Jones, K. L.; Ahn, S.; Allmond, J. M.; Ayres, A.; Bardayan, D. W.; Baugher, T.; Bazin, D.; Berryman, J. S.; Bey, A.; Bingham, C.; Cartegni, L.; Cerizza, G.; Chae, K. Y.; Cizewski, J. A.; Gade, A.; Galindo-Uribarri, A.; Garcia-Ruiz, R. F.; Grzywacz, R.; Howard, M. E.; Kozub, R. L.; Liang, J. F.; Manning, B.; Matoš, M.; McDaniel, S.; Miller, D.; Nesaraja, C. D.; O'Malley, P. D.; Padgett, S.; Padilla-Rodal, E.; Pain, S. D.; Pittman, S. T.; Radford, D. C.; Ratkiewicz, A.; Schmitt, K. T.; Shore, A.; Smith, M. S.; Stracener, D. W.; Stroberg, S. R.; Tostevin, J.; Varner, R. L.; Weisshaar, D.; Wimmer, K.; Winkler, R.

    2015-01-01

    Direct reaction techniques are powerful tools to study the single-particle nature of nuclei. Performing direct reactions on short-lived nuclei requires radioactive ion beams produced either via fragmentation or the Isotope Separation OnLine (ISOL) method. Some of the most interesting regions to study with direct reactions are close to the magic numbers where changes in shell structure can be tracked. These changes can impact the final abundances of explosive nucleosynthesis. The structure of the chain of tin isotopes is strongly influenced by the Z = 50 proton shell closure, as well as the neutron shell closures lying in the neutron-rich, N = 82, and neutron-deficient, N = 50, regions. Here, we present two examples of direct reactions on exotic tin isotopes. The first uses a one-neutron transfer reaction and a low-energy reaccelerated ISOL beam to study states in Sn-131 from across the N = 82 shell closure. The second example utilizes a one-neutron knockout reaction on fragmentation beams of neutron-deficient Sn-106,108Sn. In conclusion, In both cases, measurements of γ rays in coincidence with charged particles proved to be invaluable.

  20. Experimental studies of N/Z equilibration in peripheral collisions using fragment yield ratios

    SciTech Connect

    Keksis, A. L.; May, L. W.; Kohley, Z.; Soisson, S. N.; Stein, B. C.; Wuenschel, S.; Yennello, S. J.; Souliotis, G. A.; Veselsky, M.; Galanopoulos, S.; Shetty, D. V.; Tripathi, R.; Li, B. A.

    2010-05-15

    Peripheral collisions of {sup 40}Ca and {sup 48}Ca projectiles at 32 MeV/nucleon on {sup 112}Sn and {sup 124}Sn targets were studied in this work. The fragments of the projectile-like source (quasiprojectile) were collected with a charged-particle multidetector array. The average value of the neutron-to-proton ratio N/Z of the quasiprojectiles formed in the reactions was determined with two approaches. The first is a direct reconstruction approach using isotopically resolved fragments and is hindered by undetected neutrons leading to lower N/Z values. The second approach, based on the assumption of early fragment formation, employs yield ratios of fragment isobars and is not hindered by undetected neutrons. Using this approach, the amount of N/Z mixing that occurred in the quasiprojectiles (compared to a fully N/Z equilibrated system) was found to be approximately 53%. The experimental results were compared with model calculations. First, the phenomenological DIT (deep inelastic transfer) model was used, followed by the statistical multifragmentation model (SMM). The results of these calculations are in close agreement with the data and indicate that the mean number of undetected neutrons increases with the N/Z of the composite system, accounting for the difference observed between the two approaches of quasiprojectile N/Z determination. Second, the microscopic transport model IBUU (isospin-dependent Boltzmann-Uehling-Uhlenbeck) was employed, providing preliminary results in reasonable agreement with the data. The determination of the degree of N/Z equilibration employing the present fragment yield ratio approach may provide a valuable probe to study the isospin part of the nuclear equation of state in conjunction with detailed microscopic models of the collisions in the Fermi energy regime.

  1. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for rapid diagnosis of neonatal sepsis

    PubMed Central

    Rohit, Anusha; Maiti, Biswajit; Shenoy, Shalini; Karunasagar, Indrani

    2016-01-01

    Background & objectives: The difficulties in diagnosis of neonatal sepsis are due to varied clinical presentation, low sensitivity of blood culture which is considered the gold standard and empirical antibiotic usage affecting the outcome of results. Though polymerase chain reaction (PCR) based detection of bacterial 16S rRNA gene has been reported earlier, this does not provide identification of the causative agent. In this study, we used restriction fragment length polymorphism (RFLP) of amplified 16S rRNA gene to identify the organisms involved in neonatal sepsis and compared the findings with blood culture. Methods: Blood samples from 97 neonates were evaluated for diagnosis of neonatal sepsis using BacT/Alert (automated blood culture) and PCR-RFLP. Results: Bacterial DNA was detected by 16S rRNA gene PCR in 55 cases, while BacT/Alert culture was positive in 34 cases. Staphylococcus aureus was the most common organism detected with both methods. Klebsiella spp. was isolated from four samples by culture but was detected by PCR-RFLP in five cases while Acinetobacter spp. was isolated from one case but detected in eight cases by PCR-RFLP. The sensitivity of PCR was found to be 82.3 per cent with a negative predictive value of 85.7 per cent. Eighty of the 97 neonates had prior exposure to antibiotics. Interpretation & conclusions: The results of our study demonstrate that PCR-RFLP having a rapid turnaround time may be useful for the early diagnosis of culture negative neonatal sepsis. PMID:26997017

  2. ANOMALOUS REACTION MEAN FREE PATHS OF NUCLEAR PROJECTILE FRAGMENTS FROM HEAVY ION COLLISIONS AT 2 AGeV

    SciTech Connect

    Friedlander, E.M.; Gimpel, R.W.; Heckman, H.H.; Karant, Y.J.; Judek, B.; Ganssauge, E.

    1982-08-01

    We present in detail the description and the analysis of two independent experiments using Bevalac beams of {sup 16}O and {sup 56}Fe. From their results it is concluded that the reaction mean free paths of relativistic projectile fragments, 3 {<=} Z {<=} 26, are shorter for a few centimeters after emission than at large distances where they are compatible with values predicted from experiments on beam nuclei. The probability that this effect is due to a statistical fluctuation is <10{sup -3}. The effect is enhanced in later generations of fragments, the correlation between successive generations suggesting a kind of "memory" for the anomaly. Various systematic and spurious effects as well as conventional explanations are discussed mainly on the basis of direct experimental observations internal to our data, and found not to explain our results. The data can be interpreted by the relatively rare occurrence of anomalous fragments that interact with an unexpectedly large cross section. The statistical methods used in the analysis of the observations are fully described.

  3. Fission fragment yield distribution in the heavy-mass region from the 239Pu (nth,f ) reaction

    NASA Astrophysics Data System (ADS)

    Gupta, Y. K.; Biswas, D. C.; Serot, O.; Bernard, D.; Litaize, O.; Julien-Laferrière, S.; Chebboubi, A.; Kessedjian, G.; Sage, C.; Blanc, A.; Faust, H.; Köster, U.; Ebran, A.; Mathieu, L.; Letourneau, A.; Materna, T.; Panebianco, S.

    2017-07-01

    The fission fragment yield distribution has been measured in the 239Pu(nth,f ) reaction in the mass region of A =126 to 150 using the Lohengrin recoil-mass spectrometer. Three independent experimental campaigns were performed, allowing a significant reduction of the uncertainties compared to evaluated nuclear data libraries. The long-standing discrepancy of around 10% for the relative yield of A =134 reported in JEF-2.2 and JEFF-3.1.1 data libraries is finally solved. Moreover, the measured mass distribution in thermal neutron-induced fission does not show any significant dip around the shell closure (A =136 ) as seen in heavy-ion fission data of 208Pb(18O, f ) and 238U(18O, f ) reactions. Lastly, comparisons between our experimental data and the predictions from Monte Carlo codes (gef and fifrelin) are presented and discussed.

  4. Popping Balloons: A Case Study of Dynamical Fragmentation

    NASA Astrophysics Data System (ADS)

    Moulinet, Sébastien; Adda-Bedia, Mokhtar

    2015-10-01

    Understanding the physics of fragmentation is important in a wide range of industrial and geophysical applications. Fragmentation processes involve large strain rates and short time scales that take place during crack nucleation and propagation. Using rubber membranes, we develop an experimental analysis that enables us to track the fragmentation process in situ in both time and space. We find that bursting a highly stretched membrane yields a treelike fragmentation network that originates at a single seed crack, followed by successive crack tip-splitting events. We show that a dynamic instability drives this branching mechanism. Fragmentation occurs when the crack tip speed attains a critical velocity for which tip splitting becomes the sole available mechanism of releasing the stored elastic energy. Given the general character of the fragmentation processes, this framework should be applicable to other crack networks in brittle materials.

  5. Molecular beam studies of reaction dynamics

    SciTech Connect

    Lee, Y.T.

    1987-03-01

    Purpose of this research project is two-fold: (1) to elucidate detailed dynamics of simple elementary reactions which are theoretically important and to unravel the mechanism of complex chemical reactions or photo chemical processes which play an important role in many macroscopic processes and (2) to determine the energetics of polyatomic free radicals using microscopic experimental methods. Most of the information is derived from measurement of the product fragment translational energy and angular distributions using unique molecular beam apparati designed for these purposes.

  6. Experimental fission study using multi-nucleon transfer reactions

    NASA Astrophysics Data System (ADS)

    Nishio, Katsuhisa; Hirose, Kentaro; Léguillon, Romain; Makii, Hiroyuki; Orlandi, Riccardo; Tsukada, Kazuaki; Smallcombe, James; Chiba, Satoshi; Aritomo, Yoshihiro; Tanaka, Shouya; Ohtsuki, Tsutomu; Tsekhanovich, Igor; Petrache, Costel M.; Andreyev, Andrei

    2017-09-01

    It is shown that the multi-nucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multi-nucleon transfer channels of the reactions of 18O+232Th, 18O+238U and 18O+248Cm are used to study fission for various nuclei from many excited states. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation-dissipation model. Role of multi-chance fission in fission fragment mass distributions is discussed, where it is shown that mass-asymmetric structure remaining at high excitation energies originates from low-excited nuclei by evaporation of neutrons.

  7. Studies of Fission Fragment Rocket Engine Propelled Spacecraft

    NASA Technical Reports Server (NTRS)

    Werka, Robert O.; Clark, Rodney; Sheldon, Rob; Percy, Thomas K.

    2014-01-01

    The NASA Office of Chief Technologist has funded from FY11 through FY14 successive studies of the physics, design, and spacecraft integration of a Fission Fragment Rocket Engine (FFRE) that directly converts the momentum of fission fragments continuously into spacecraft momentum at a theoretical specific impulse above one million seconds. While others have promised future propulsion advances if only you have the patience, the FFRE requires no waiting, no advances in physics and no advances in manufacturing processes. Such an engine unequivocally can create a new era of space exploration that can change spacecraft operation. The NIAC (NASA Institute for Advanced Concepts) Program Phase 1 study of FY11 first investigated how the revolutionary FFRE technology could be integrated into an advanced spacecraft. The FFRE combines existent technologies of low density fissioning dust trapped electrostatically and high field strength superconducting magnets for beam management. By organizing the nuclear core material to permit sufficient mean free path for escape of the fission fragments and by collimating the beam, this study showed the FFRE could convert nuclear power to thrust directly and efficiently at a delivered specific impulse of 527,000 seconds. The FY13 study showed that, without increasing the reactor power, adding a neutral gas to the fission fragment beam significantly increased the FFRE thrust through in a manner analogous to a jet engine afterburner. This frictional interaction of gas and beam resulted in an engine that continuously produced 1000 pound force of thrust at a delivered impulse of 32,000 seconds, thereby reducing the currently studied DRM 5 round trip mission to Mars from 3 years to 260 days. By decreasing the gas addition, this same engine can be tailored for much lower thrust at much higher impulse to match missions to more distant destinations. These studies created host spacecraft concepts configured for manned round trip journeys. While the

  8. Activity-Directed Synthesis with Intermolecular Reactions: Development of a Fragment into a Range of Androgen Receptor Agonists.

    PubMed

    Karageorgis, George; Dow, Mark; Aimon, Anthony; Warriner, Stuart; Nelson, Adam

    2015-11-09

    Activity-directed synthesis (ADS), a novel discovery approach in which bioactive molecules emerge in parallel with associated syntheses, was exploited to develop a weakly binding fragment into novel androgen receptor agonists. Harnessing promiscuous intermolecular reactions of carbenoid compounds enabled highly efficient exploration of chemical space. Four substrates were prepared, yet exploited in 326 reactions to explore diverse chemical space; guided by bioactivity alone, the products of just nine of the reactions were purified to reveal diverse novel agonists with up to 125-fold improved activity. Remarkably, one agonist stemmed from a novel enantioselective transformation; this is the first time that an asymmetric reaction has been discovered solely on the basis of the biological activity of the product. It was shown that ADS is a significant addition to the lead generation toolkit, enabling the efficient and rapid discovery of novel, yet synthetically accessible, bioactive chemotypes. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

  9. Molecular variation analysis of Aspergillus flavus using polymerase chain reaction-restriction fragment length polymorphism of the internal transcribed spacer rDNA region

    PubMed Central

    Zarrin, Majid; Erfaninejad, Maryam

    2016-01-01

    Aspergillus flavus is the second most common disease-causing species of Aspergillus in humans. The fungus is frequently associated with life-threatening infections in immunocompromised hosts. The primary aim of the present study was to analyze the genetic variability among different isolates of A. flavus using polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP). A total of 62 A. flavus isolates were tested in the study. Molecular variability was searched for by analysis of the PCR amplification of the internal transcribed spacer (ITS) regions of ribosomal DNA using restriction enzymes. PCR using primers for ITS1 and ITS4 resulted in a product of ~600 bp. Amplicons were subjected to digestion with restriction endonucleases EcoRI, HaeIII and TaqI. Digestion of the PCR products using these restriction enzymes produced different patterns of fragments among the isolates, with different sizes and numbers of fragments, revealing genetic variability. In conclusion, ITS-RFLP is a useful molecular tool in screening for nucleotide polymorphisms among A. flavus isolates. PMID:27588085

  10. Fragmentation of silicon microclusters: A molecular-dynamics study

    NASA Astrophysics Data System (ADS)

    Feuston, B. P.; Kalia, R. K.; Vashishta, P.

    1987-04-01

    A detailed molecular-dynamics (MD) study has been performed to (i) enumerate ground-state and finite-temperature structures and (ii) investigate the nature of fragmentation for SiN clusters (N=2-14), using the Stillinger-Weber three-body interaction potential. We investigate all underlying mechanically stable structures visited by the system in the equilibrium state. Results indicate that the presence of magic numbers, unusually stable finite-temperature clusters Si4, Si6, and Si10 as determined by the photofragmentation experiment of Bloomfield, Freeman, and Brown is dependent upon the topology and energetics of high-energy bound structures rather than upon the structure and ground-state energies at zero temperature.

  11. Role of angular momentum in the production of complex fragments in fusion and quasifission reactions

    SciTech Connect

    Kalandarov, Sh. A.; Adamian, G. G.; Antonenko, N. V.; Scheid, W.

    2011-05-15

    The influence of angular momentum on the competition between complete fusion followed by the decay of compound nucleus and quasifission channels is treated within the dinuclear system model. The charge distributions of the products in the reactions {sup 28}Si+{sup 96}Zr, {sup 4}He+{sup 130}Te, and {sup 40}Ca+{sup 82}Kr are predicted at bombarding energies above the Coulomb barrier. The results of calculations for the reactions {sup 93}Nb+{sup 9}Be,{sup 12}C,{sup 27}Al; {sup 84}Kr+{sup 27}Al; {sup 86}Kr+{sup 63}Cu; {sup 139}La+{sup 12}C,{sup 27}Al; and {sup 45}Sc+{sup 65}Cu are compared with the available experimental data.

  12. Hydride transfer reactions via ion-neutral complex: fragmentation of protonated N-benzylpiperidines and protonated N-benzylpiperazines in mass spectrometry.

    PubMed

    Chai, Yunfeng; Jiang, Kezhi; Pan, Yuanjiang

    2010-05-01

    An ion-neutral complex (INC)-mediated hydride transfer reaction was observed in the fragmentation of protonated N-benzylpiperidines and protonated N-benzylpiperazines in electrospray ionization mass spectrometry. Upon protonation at the nitrogen atom, these compounds initially dissociated to an INC consisting of [RC(6)H(4)CH(2)](+) (R = substituent) and piperidine or piperazine. Although this INC was unstable, it did exist and was supported by both experiments and density functional theory (DFT) calculations. In the subsequent fragmentation, hydride transfer from the neutral partner to the cation species competed with the direct separation. The distribution of the two corresponding product ions was found to depend on the stabilization energy of this INC, and it was also approved by the study of substituent effects. For monosubstituted N-benzylpiperidines, strong electron-donating substituents favored the formation of [RC(6)H(4)CH(2)](+), whereas strong electron-withdrawing substituents favored the competing hydride transfer reaction leading to a loss of toluene. The logarithmic values of the abundance ratios of the two ions were well correlated with the nature of the substituents, or rather, the stabilization energy of this INC.

  13. A Semi-Classical Model to Study Nuclear Fragmentation

    NASA Astrophysics Data System (ADS)

    Navarro, Martha; Chernomoretz, Ariel; Dorso, Claudio; Lopez, Jorge

    1999-10-01

    A semi-classical model based on the use of molecular dynamics has been developed for the study of heavy-ion reactions at intermediate energies. The model reproduces nucleon-nucleon cross sections through the use of a two-body potential. The study covers several characteristics of heavy-ion collisions, such as formation of necks, and formation of intermediate residue. Preliminary results on the use of the model to study the caloric curve of nuclear matter and the temperature evolution of the system are also discussed.

  14. Detection and differentiation of filarial parasites by universal primers and polymerase chain reaction-restriction fragment length polymorphism analysis.

    PubMed

    Nuchprayoon, Surang; Junpee, Alisa; Poovorawan, Yong; Scott, Alan L

    2005-11-01

    Filarial nematode parasites are a serious cause of morbidity in humans and animals. Identification of filarial infection using traditional morphologic criteria can be difficult and lead to misdiagnosis. We report on a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)-based method to detect and differentiate a broad range of filarial species in a single PCR. The first internal transcribed spacer 1 (ITS1) along with the flanking 18S and 5.8S ribosomal DNA (rDNA) were isolated and cloned from Wuchereria bancrofti, Brugia malayi, and Brugia pahangi. Sequence analysis identified conserved sites in the 18S and 5.8S rDNA sequence that could be used as universal priming sites to generate ITS1-distinctive PCR products that were useful for distinguishing filariae at the genus level. The addition of a digestion of the ITS1 PCR product with the restriction endonuclease Ase I generated a fragment profile that allowed differentiation down to the species level for W. bancrofti, B. malayi, B. pahangi, Dirofilaria immitis, and D. repens. The PCR-RFLP of ITS1 rDNA will be useful in diagnosing and differentiating filarial parasites in human, animal reservoir hosts, and mosquito vectors in disease-endemic areas.

  15. Chemical potential and symmetry energy for intermediate-mass fragment production in heavy ion reactions near the Fermi energy

    NASA Astrophysics Data System (ADS)

    Liu, X.; Lin, W.; Huang, M.; Wada, R.; Wang, J.; Bonasera, A.; Zheng, H.; Chen, Z.; Kowalski, S.; Keutgen, T.; Hagel, K.; Qin, L.; Natowitz, J. B.; Materna, T.; Sahu, P. K.; Barbui, M.; Bottosso, C.; Rodrigues, M. R. D.

    2017-04-01

    Ratios of differential chemical potential values relative to the temperature, (μn-μp)/T , extracted from isotope yields of 13 reaction systems at 40 MeV/nucleon are compared to those of a quantum statistical model to determine the temperature and symmetry energy values of the fragmenting system. The experimental (μn-μp)/T values are extracted based on the modified Fisher model. Using the density value of ρ /ρ0=0.56 from the previous analysis, the temperature and symmetry energy values of T =4.6 ±0.4 MeV and asym=23.6 ±2.1 MeV are extracted in a framework of a quantum statistical model. These values agree well with those of the previous work, in which a self-consistent method was utilized with antisymmetrized molecular dynamics simulations. The extracted temperature and symmetry energies are discussed together with other experimental values published in literature.

  16. New Approach for Studying Slow Fragmentation Kinetics in FT-ICR: Surface-Induced Dissociation Combined with Resonant Ejection

    SciTech Connect

    Laskin, Julia; Futrell, Jean H.

    2015-02-01

    We introduce a new approach for studying the kinetics of large ion fragmentation in the gas phase by coupling surface-induced dissociation (SID) in a Fourier transform ion cyclotron resonance mass spectrometer with resonant ejection of selected fragment ions using a relatively short (5 ms) ejection pulse. The approach is demonstrated for singly protonated angiotensin III ions excited by collisions with a self-assembled monolayer of alkylthiol on gold (HSAM). The overall decomposition rate and rate constants of individual reaction channels are controlled by varying the kinetic energy of the precursor ion in a range of 65–95 eV. The kinetics of peptide fragmentation are probed by varying the delay time between resonant ejection and fragment ion detection at a constant total reaction time. RRKM modeling indicates that the shape of the kinetics plots is strongly affected by the shape and position of the energy deposition function (EDF) describing the internal energy distribution of the ion following ion-surface collision. Modeling of the kinetics data provides detailed information on the shape of the EDF and energy and entropy effects of individual reaction channels.

  17. Experimental Study of Serpentinization Reactions

    NASA Technical Reports Server (NTRS)

    Cohen, B. A.; Brearley, A. J.; Ganguly, J.; Liermann, H.-P.; Keil, K.

    2004-01-01

    Current carbonaceous chondrite parent-body thermal models [1-3] produce scenarios that are inconsistent with constraints on aqueous alteration conditions based on meteorite mineralogical evidence, such as phase stability relationships within the meteorite matrix minerals [4] and isotope equilibration arguments [5, 6]. This discrepancy arises principally because of the thermal runaway effect produced by silicate hydration reactions (here loosely called serpentinization, as the principal products are serpentine minerals), which are so exothermic as to produce more than enough heat to melt more ice and provide a self-sustaining chain reaction. One possible way to dissipate the heat of reaction is to use a very small parent body [e.g., 2] or possibly a rubble pile model. Another possibility is to release this heat more slowly, which depends on the alteration reaction path and kinetics.

  18. Mass and charge distributions in iron-induced reactions and excitation energy division between the fragments of the 672-MeV 56Fe + 165Ho reaction

    SciTech Connect

    Madani, Houria

    1993-01-01

    The projectile-like and target-like fragments produced by the 12-MeV/nucleon 56Fe + 165Ho reaction were detected in coincidence. The measured parameters were the mass, charge, kinetic energy scattering angle of the projectile-like fragments, and the scattering angle of the target-like fragments. The mass and charge distributions of the projectile-like fragments were generated as a function of energy loss, and characterized by their centroids, variances, and correlation coefficients. The neutron drift of the measured projectile-like products is mostly due to evaporative processes, while the charge drift is a result of a net transfer of protons from the projectile-like fragment to the target-like fragment. The result is a weak drift of the system towards mass asymmetry. The predictions of two nucleon exchange models are compared to the experimental results of the 672-MeV 56Fe + 165Ho reaction and other Fe-induced reactions. The fairly good agreement between the experimental and theoretical variances verifies the prevalence of a nucleon exchange mechanism in these reactions. The information from the coincidence measurement and two-body kinematics are used to reconstruct the pre-evaporation masses of the projectile-like and target-like fragments of the reaction. Statistical evaporation calculations are used to translate these masses into excitation energies of the primary fragments. The ratio of excitation energy stored in the projectile-Mm fragment decreases with increasing energy loss, in qualitative agreement with previous measurements; however, higher ratios are observed for the 672-MeV 56Fe on 165Ho system.

  19. Mass and charge distributions in iron-induced reactions and excitation energy division between the fragments of the 672-MeV [sup 56]Fe + [sup 165]Ho reaction

    SciTech Connect

    Madani, H.

    1993-01-01

    The projectile-like and target-like fragments produced by the 12-MeV/nucleon [sup 56]Fe + [sup 165]Ho reaction were detected in coincidence. The measured parameters were the mass, charge, kinetic energy scattering angle of the projectile-like fragments, and the scattering angle of the target-like fragments. The mass and charge distributions of the projectile-like fragments were generated as a function of energy loss, and characterized by their centroids, variances, and correlation coefficients. The neutron drift of the measured projectile-like products is mostly due to evaporative processes, while the charge drift is a result of a net transfer of protons from the projectile-like fragment to the target-like fragment. The result is a weak drift of the system towards mass asymmetry. The predictions of two nucleon exchange models are compared to the experimental results of the 672-MeV [sup 56]Fe + [sup 165]Ho reaction and other Fe-induced reactions. The fairly good agreement between the experimental and theoretical variances verifies the prevalence of a nucleon exchange mechanism in these reactions. The information from the coincidence measurement and two-body kinematics are used to reconstruct the pre-evaporation masses of the projectile-like and target-like fragments of the reaction. Statistical evaporation calculations are used to translate these masses into excitation energies of the primary fragments. The ratio of excitation energy stored in the projectile-Mm fragment decreases with increasing energy loss, in qualitative agreement with previous measurements; however, higher ratios are observed for the 672-MeV [sup 56]Fe on [sup 165]Ho system.

  20. Nuclear Reaction Recoil Fragments as Probes of Electronic Structure in Condensed Matter.

    NASA Astrophysics Data System (ADS)

    Bishop, Judith Lance

    Ambiguities in the stopping powers of many solids are frequently observed. When the cross-sections for constituent atoms are reliable, the deviations can be discussed meaningfully. This work measures cross-sections for boron, hexagonal boron -nitride, cubic boron-nitride (borazon) and cubic boron -phosphide and suggests that these samples may provide reasonable atomic cross-sections. Intermolecular deviations may exist, but molecular deviations appear to be absent. The method used for measuring cross-sections is based on information obtained from radiating Li('7) projectiles, whose motion and internal excitation are initiated by the thermal nuclear reaction ('10)B(n,(alpha))('7)Li* These projectiles have well defined initial momentum and spend their entire lives confined to the stopping medium.

  1. Nuclear-reaction recoil fragments as probes of electronic structure in condensed matter

    SciTech Connect

    Bishop, J.L.

    1986-01-01

    Ambiguities in the stopping powers of many solids are frequently observed. When the cross-sections for constituent atoms are reliable, the deviations can be discussed meaningfully. This work measures cross-sections for boron, hexagonal boron-nitride, cubic boron-nitride (borazon) and cubic boron-phosphide and suggests that these samples may provide reasonable atomic cross-sections. Intermolecular deviations may exist, but molecular deviations appear to be absent. The method used for measuring cross-sections is based on information obtained from radiating Li{sup 7} projectiles, whose motion and internal excitation are initiated by the thermal nuclear reaction {sup 10}B(n,{alpha}){sup 7}Li{sup *}. These projectiles have well defined initial momentum and spend their entire lives confined to the stopping medium.

  2. Spectroscopic investigation of the reaction mechanism of CopB-B, the catalytic fragment from an archaeal thermophilic ATP-driven heavy metal transporter.

    PubMed

    Völlmecke, Christian; Kötting, Carsten; Gerwert, Klaus; Lübben, Mathias

    2009-11-01

    The mechanism of ATP hydrolysis of a shortened variant of the heavy metal-translocating P-type ATPase CopB of Sulfolobus solfataricus was studied. The catalytic fragment, named CopB-B, comprises the nucleotide binding and phosphorylation domains. We demonstrated stoichiometric high-affinity binding of one nucleotide to the protein (K(diss) 1-20 microm). Mg is not necessary for nucleotide association but is essential for the phosphatase activity. Binding and hydrolysis of ATP released photolytically from the caged precursor nitrophenylethyl-ATP was measured at 30 degrees C by infrared spectroscopy, demonstrating that phosphate groups are not involved in nucleotide binding. The hydrolytic kinetics was biphasic, and provides evidence for at least one reaction intermediate. Modelling of the forward reaction gave rise to three kinetic states connected by two intrinsic rate constants. The lower kinetic constant (k(1) = 4.7 x 10(-3) s(-1) at 30 degrees C) represents the first and rate-limiting reaction, probably reflecting the transition between the open and closed conformations of the domain pair. The subsequent step has a faster rate (k(2) = 17 x 10(-3) s(-1) at 30 degrees C), leading to product formation. Although the latter appears to be a single step, it probably comprises several reactions with presently unresolved intermediates. Based on these data, we suggest a model of the hydrolytic mechanism.

  3. Personality dependent effects of the ACTH 4--10 fragment on test performances and on concomitant autonomic reactions.

    PubMed

    Breier, C; Kain, H; Konzett, H

    1979-11-01

    The effect of the ACTH-fragment 4--10 (30 mg SC) on a mental performance test and on some concomitant cardiovascular changes was investigated in comparison with a placebo in a double blind cross-over study. The subjects were either mainly extraverted or mainly introverted according to Eysenck's 'Maudsley Personality Inventory'. Under the influence of the heptapeptide extraverted subjects achieved a higher total score in the mental task performance with a smaller increase of forearm blood flow and of heart rate than under the influence of the placebo. In contrast, under the influence of the placebo introverted subjects achieved a higher total score in the mental task performance with a smaller increase of forearm blood flow and of heart rate than under the influence of the ACTH-fragment. Personality, therefore, determines to some degree how this centrally acting heptapeptide influences efficiency in the mental task performance and the concomitant cardiovascular changes.

  4. Rapid Identification Method of Omphalotus japonicus by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP).

    PubMed

    Sugano, Yohei; Sakata, Kozue; Nakamura, Kosuke; Noguchi, Akio; Fukuda, Nozomi; Suzuki, Tomohiro; Kondo, Kazunari

    2017-01-01

    Omphalotus japonicus is a poisonous mushroom that grows in Japan. It can be mistaken for edible mushrooms (Shiitake, Hiratake and Mukitake), and if ingested, it causes food poisoning within 30 min to 1 hr. We established a rapid detection method using PCR-RFLP to identify O. japonicus by restriction digestion of the amplified ITS region. By using Sau96I, Bpu10I, SfcI or DrdI/HincII as a restriction enzyme, it was possible to rapidly identify and discriminate O. japonicus based on the fragment length. This study also provided a short PCR-RFLP system comprising amplification and digestion of a short 200-bp DNA fragment within the ITS region. The system could identify and discriminate O. japonicus after in vitro gastric digestion of native and heated mushroom samples as a model of food poisoning. In addition, a confirmatory assay using real-time PCR was developed to achieve more sensitive detection of O. japonicus.

  5. Rational Design of High-Number dsDNA Fragments Based on Thermodynamics for the Construction of Full-Length Genes in a Single Reaction.

    PubMed

    Birla, Bhagyashree S; Chou, Hui-Hsien

    2015-01-01

    Gene synthesis is frequently used in modern molecular biology research either to create novel genes or to obtain natural genes when the synthesis approach is more flexible and reliable than cloning. DNA chemical synthesis has limits on both its length and yield, thus full-length genes have to be hierarchically constructed from synthesized DNA fragments. Gibson Assembly and its derivatives are the simplest methods to assemble multiple double-stranded DNA fragments. Currently, up to 12 dsDNA fragments can be assembled at once with Gibson Assembly according to its vendor. In practice, the number of dsDNA fragments that can be assembled in a single reaction are much lower. We have developed a rational design method for gene construction that allows high-number dsDNA fragments to be assembled into full-length genes in a single reaction. Using this new design method and a modified version of the Gibson Assembly protocol, we have assembled 3 different genes from up to 45 dsDNA fragments at once. Our design method uses the thermodynamic analysis software Picky that identifies all unique junctions in a gene where consecutive DNA fragments are specifically made to connect to each other. Our novel method is generally applicable to most gene sequences, and can improve both the efficiency and cost of gene assembly.

  6. Experimental and numerical studies of high-velocity impact fragmentation

    SciTech Connect

    Kipp, M.E.; Grady, D.E.; Swegle, J.W.

    1993-08-01

    Developments are reported in both experimental and numerical capabilities for characterizing the debris spray produced in penetration events. We have performed a series of high-velocity experiments specifically designed to examine the fragmentation of the projectile during impact. High-strength, well-characterized steel spheres (6.35 mm diameter) were launched with a two-stage light-gas gun to velocities in the range of 3 to 5 km/s. Normal impact with PMMA plates, thicknesses of 0.6 to 11 mm, applied impulsive loads of various amplitudes and durations to the steel sphere. Multiple flash radiography diagnostics and recovery techniques were used to assess size, velocity, trajectory and statistics of the impact-induced fragment debris. Damage modes to the primary target plate (plastic) and to a secondary target plate (aluminum) were also evaluated. Dynamic fragmentation theories, based on energy-balance principles, were used to evaluate local material deformation and fracture state information from CTH, a three-dimensional Eulerian solid dynamics shock wave propagation code. The local fragment characterization of the material defines a weighted fragment size distribution, and the sum of these distributions provides a composite particle size distribution for the steel sphere. The calculated axial and radial velocity changes agree well with experimental data, and the calculated fragment sizes are in qualitative agreement with the radiographic data. A secondary effort involved the experimental and computational analyses of normal and oblique copper ball impacts on steel target plates. High-resolution radiography and witness plate diagnostics provided impact motion and statistical fragment size data. CTH simulations were performed to test computational models and numerical methods.

  7. Model for projectile fragmentation: Case study for Ni on Ta and Be, and Xe on Al

    SciTech Connect

    Mallik, S.; Chaudhuri, G.; Das Gupta, S.

    2011-04-15

    For projectile fragmentation, we work out details of a model whose origin can be traced back to the Bevalac era. The model positions itself between the phenomenological empirical parametrization of fragmentation cross sections (EPAX) and microscopic transport models like the heavy ion phase-space exploration (HIPSE) model and antisymmetrized molecular dynamics (AMD) model. We apply the model to some recent data of projectile fragmentation of Ni on Ta and Be at beam energy 140 MeV/nucleon and some older data of Xe on Al at beam energy 790 MeV/nucleon. Reasonable values of cross sections for various composites populated in the reactions are obtained.

  8. Kinetic studies of elementary chemical reactions

    SciTech Connect

    Durant, J.L. Jr.

    1993-12-01

    This program concerning kinetic studies of elementary chemical reactions is presently focussed on understanding reactions of NH{sub x} species. To reach this goal, the author is pursuing experimental studies of reaction rate coefficients and product branching fractions as well as using electronic structure calculations to calculate transition state properties and reaction rate calculations to relate these properties to predicted kinetic behavior. The synergy existing between the experimental and theoretical studies allow one to gain a deeper insight into more complex elementary reactions.

  9. Improved Polymerase Chain Reaction-restriction Fragment Length Polymorphism Genotyping of Toxic Pufferfish by Liquid Chromatography/Mass Spectrometry

    PubMed Central

    Miyaguchi, Hajime

    2016-01-01

    An improved version of a polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method for genotyping toxic pufferfish species by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) is described. DNA extraction is carried out using a silica membrane-based DNA extraction kit. After the PCR amplification using a detergent-free PCR buffer, restriction enzymes are added to the solution without purifying the reaction solution. A reverse-phase silica monolith column and a Fourier transform high resolution mass spectrometer having a modified Kingdon trap analyzer are employed for separation and detection, respectively. The mobile phase, consisting of 400 mM 1,1,1,3,3,3-hexafluoro-2-propanol, 15 mM triethylamine (pH 7.9) and methanol, is delivered at a flow rate of 0.4 ml/min. The cycle time for LC/ESI-MS analysis is 8 min including equilibration of the column. Deconvolution software having an isotope distribution model of the oligonucleotide is used to calculate the corresponding monoisotopic mass from the mass spectrum. For analysis of oligonucleotides (range 26-79 nucleotides), mass accuracy was 0.62 ± 0.74 ppm (n = 280) and excellent accuracy and precision were sustained for 180 hr without use of a lock mass standard. PMID:27684516

  10. Fragment Molecular Orbital method-based Molecular Dynamics (FMO-MD) as a simulator for chemical reactions in explicit solvation.

    PubMed

    Komeiji, Yuto; Ishikawa, Takeshi; Mochizuki, Yuji; Yamataka, Hiroshi; Nakano, Tatsuya

    2009-01-15

    Fragment Molecular Orbital based-Molecular Dynamics (FMO-MD, Komeiji et al., Chem Phys Lett 2003, 372, 342) is an ab initio MD method suitable for large molecular systems. Here, FMO-MD was implemented to conduct full quantum simulations of chemical reactions in explicit solvation. Several FMO-MD simulations were performed for a sphere of water to find a suitable simulation protocol. It was found that annealing of the initial configuration by a classical MD brought the subsequent FMO-MD trajectory to faster stabilization, and also that use of bond constraint in the FMO-MD heating stage effectively reduced the computation time. Then, the blue moon ensemble method (Sprik and Ciccotti, J Chem Phys 1998, 109, 7737) was implemented and was tested by calculating free energy profiles of the Menschutkin reaction (H3N + CH3Cl --> +H3NCH3 + Cl-) in the presence and absence of the solvent water via FMO-MD. The obtained free energy profiles were consistent with the Hammond postulate in that stabilization of the product by the solvent, namely hydration of Cl-, shifted the transition state to the reactant-side. Based on these FMO-MD results, plans for further improvement of the method are discussed. Copyright 2008 Wiley Periodicals, Inc.

  11. Effects of forest fragmentation on nocturnal Asian birds: A case study from Xishuangbanna, China.

    PubMed

    K Dayananda, Salindra; Goodale, Eben; Lee, Myung-Bok; Liu, Jia-Jia; Mammides, Christos; O Pasion, Bonifacio; Quan, Rui-Chang; W Ferry Slik, J; Sreekar, Rachakonda; W Tomlinson, Kyle; Yasuda, Mika

    2016-05-18

    Owls have the potential to be keystone species for conservation in fragmented landscapes, as the absence of these predators could profoundly change community structure. Yet few studies have examined how whole communities of owls respond to fragmentation, especially in the tropics. When evaluating the effect of factors related to fragmentation, such as fragment area and distance to the edge, on these birds, it is also important in heterogeneous landscapes to ask how 'location factors' such as the topography, vegetation and soil of the fragment predict their persistence. In Xishuangbanna, southwest China, we established 43 transects (200 m×60 m) within 20 forest fragments to sample nocturnal birds, both visually and aurally. We used a multimodel inference approach to identify the factors that influence owl species richness, and generalized linear mixed models to predict the occurrence probabilities of each species. We found that fragmentation factors dominated location factors, with larger fragments having more species, and four of eight species were significantly more likely to occur in large fragments. Given the potential importance of these birds on regulating small mammal and other animal populations, and thus indirectly affecting seed dispersal, we suggest further protection of large fragments and programs to increase their connectivity to the remaining smaller fragments.

  12. Effects of forest fragmentation on nocturnal Asian birds: A case study from Xishuangbanna, China

    PubMed Central

    DAYANANDA, Salindra K.; GOODALE, Eben; LEE, Myung-bok; LIU, Jia-Jia; MAMMIDES, Christos; PASION, Bonifacio O.; QUAN, Rui-Chang; SLIK, J. W. Ferry; SREEKAR, Rachakonda; TOMLINSON, Kyle W.; YASUDA, Mika

    2016-01-01

    Owls have the potential to be keystone species for conservation in fragmented landscapes, as the absence of these predators could profoundly change community structure. Yet few studies have examined how whole communities of owls respond to fragmentation, especially in the tropics. When evaluating the effect of factors related to fragmentation, such as fragment area and distance to the edge, on these birds, it is also important in heterogeneous landscapes to ask how ‘location factors’ such as the topography, vegetation and soil of the fragment predict their persistence. In Xishuangbanna, southwest China, we established 43 transects (200 m×60 m) within 20 forest fragments to sample nocturnal birds, both visually and aurally. We used a multimodel inference approach to identify the factors that influence owl species richness, and generalized linear mixed models to predict the occurrence probabilities of each species. We found that fragmentation factors dominated location factors, with larger fragments having more species, and four of eight species were significantly more likely to occur in large fragments. Given the potential importance of these birds on regulating small mammal and other animal populations, and thus indirectly affecting seed dispersal, we suggest further protection of large fragments and programs to increase their connectivity to the remaining smaller fragments. PMID:27265653

  13. Heavy-ion fragmentation studies in thick water absorbers

    NASA Astrophysics Data System (ADS)

    Shavers, M. R.; Miller, J.; Schimmerling, W.; Wilson, J. W.; Townsend, L. W.

    Proposed long-term space missions could expose crewmembers to significant fluxes of galactic cosmic radiation (GCR) particles and secondary particles created from nuclear collisions. An assessment of radiobiological risks is dependent upon an accurate description of the charged-particle radiation field inside the human body. As shield thickness increases and the incident ions are slowed, the production of secondary particles contributes an increasingly significant fraction of the total dose until eventually secondary particles become more important than the primary particles. The nuclear mean free path of the GCR ions (which usually have nuclear charge between 1 (protons) and 26 (iron), both inclusive) are comparable with thicknesses typical of spacecraft structures and the human body. Collisions in these media will create projectile and target fragments with charge less than that of the primary particle, and each interaction event can have a multiplicity of more than one emerging interaction product. Projectile fragments usually continue on with very nearly the velocity of the primary ion (the so-called straightahead approximation). Having sufficient energy, the fragments may collide with atomic nuclei in thick shields and create a second generation of fragments, and so on. Target fragments are emitted from a struck nucleus, usually with much lower energy than projectile fragments and nearly isotropically in the rest frame of the absorbing medium. The resulting spectrum of particles and their energy loss rates will be very different from that in the unshielded environment, will determine the radiobiological impact on exposed living tissues -- whether in space or in ground-based radiobiology experiments -- and will play an important role in radiation effects on microelectronics.

  14. Heavy-ion fragmentation studies in thick water absorbers

    NASA Technical Reports Server (NTRS)

    Shavers, M. R.; Miller, J.; Schimmerling, W.; Wilson, J. W.; Townsend, L. W.

    1993-01-01

    Proposed long-term space missions could expose crewmembers to significant fluxes of galactic cosmic radiation (GCR) particles and secondary particles created from nuclear collisions. An assessment of radiobiological risks is dependent upon an accurate description of the charged-particle radiation field inside the human body. As shield thickness increases and the incident ions are slowed, the production of secondary particles contributes an increasingly significant fraction of the total dose until eventually secondary particles become more important than the primary particles. The nuclear mean free path of the GCR ions (which usually have nuclear charge between 1 (protons) and 26 (iron), both inclusive) are comparable with thicknesses typical of spacecraft structures and the human body. Collisions in these media will create projectile and target fragments with charge less than that of the primary particle, and each interaction event can have a multiplicity of more than one emerging interaction product. Projectile fragments usually continue on with very nearly the velocity of the primary ion (the so-called straightahead approximation). Having sufficient energy, the fragments may collide with atomic nuclei in thick shields and create a second generation of fragments, and so on. Target fragments are emitted from a struck nucleus, usually with much lower energy than projectile fragments and nearly isotropically in the rest frame of the absorbing medium. The resulting spectrum of particles and their energy loss rates will be very different from that in the unshielded environment, will determine the radiobiological impact on exposed living tissues -- whether in space or in ground-based radiobiology experiments -- and will play an important role in radiation effects on microelectronics.

  15. Double differential cross section for light mass fragment production on tens of MeV proton, deuteron, helium and carbon induced reactions

    NASA Astrophysics Data System (ADS)

    Sanami, Toshiya; Yamaguchi, Yuji; Uozumi, Yusuke; Hagiwara, Masayuki; Koba, Yusuke

    2017-09-01

    Double differential cross sections (DDXs) of light mass fragment (LMFs - Li,Be,B,C,N and O) productions were measured for tens of MeV proton, deuteron helium and carbon induced reactions on Be, C, Al, Ti and Cu targets. The incident energies for the measurements were chosen to allow us to compare DDXs with same incident energy but different projectiles on various targets. Systematic data were obtained to see the differences between projectile energies, particles, targets and emitted particles. From the comparison, reaction processes of not only evaporation from complete fusion nucleus, but also scattering, pickup, stripping and projectile fragmentation were observed.

  16. Iron meteorite fragment studied by atomic and nuclear analytical methods

    NASA Astrophysics Data System (ADS)

    Cesnek, Martin; Štefánik, Milan; Kmječ, Tomáš; Miglierini, Marcel

    2016-10-01

    Chemical and structural compositions of a fragment of Sikhote-Alin iron meteorite were investigated by X-ray fluorescence analysis (XRF), neutron activation analysis (NAA) and Mössbauer spectroscopy (MS). XRF and NAA revealed the presence of chemical elements which are characteristic for iron meteorites. XRF also showed a significant amount of Si and Al on the surface of the fragment. MS spectra revealed possible presence of α-Fe(Ni, Co) phase with different local Ni concentration. Furthermore, paramagnetic singlet was detected in Mössbauer spectra recorded at room temperature and at 4.2 K.

  17. Study of Analytic Statistical Model for Decay of Light and Medium Mass Nuclei in Nuclear Fragmentation

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Wilson, John W.

    1996-01-01

    The angular momentum independent statistical decay model is often applied using a Monte-Carlo simulation to describe the decay of prefragment nuclei in heavy ion reactions. This paper presents an analytical approach to the decay problem of nuclei with mass number less than 60, which is important for galactic cosmic ray (GCR) studies. This decay problem of nuclei with mass number less than 60 incorporates well-known levels of the lightest nuclei (A less than 11) to improve convergence and accuracy. A sensitivity study of the model level density function is used to determine the impact on mass and charge distributions in nuclear fragmentation. This angular momentum independent statistical decay model also describes the momentum and energy distribution of emitted particles (n, p, d, t, h, and a) from a prefragment nucleus.

  18. High-resolution (e, 2e + ion) study of electron-impact ionization and fragmentation of methane

    SciTech Connect

    Ren, Xueguang Pflüger, Thomas; Weyland, Marvin; Baek, Woon Yong; Rabus, Hans; Ullrich, Joachim; Dorn, Alexander

    2015-05-07

    The ionization and fragmentation of methane induced by low-energy (E{sub 0} = 66 eV) electron-impact is investigated using a reaction microscope. The momentum vectors of all three charged final state particles, two outgoing electrons, and one fragment ion, are detected in coincidence. Compared to the earlier study [Xu et al., J. Chem. Phys. 138, 134307 (2013)], considerable improvements to the instrumental mass and energy resolutions have been achieved. The fragment products CH{sub 4}{sup +}, CH{sub 3}{sup +}, CH{sub 2}{sup +}, CH{sup +}, and C{sup +} are clearly resolved. The binding energy resolution of ΔE = 2.0 eV is a factor of three better than in the earlier measurements. The fragmentation channels are investigated by measuring the ion kinetic energy distributions and the binding energy spectra. While being mostly in consistence with existing photoionization studies the results show differences including missing fragmentation channels and previously unseen channels.

  19. Soft-x-ray fragmentation studies of molecular ions

    NASA Astrophysics Data System (ADS)

    Wolf, Andreas; Pedersen, Henrik B.; Lammich, Lutz; Jordon-Thaden, Brandon; Altevogt, Simon; Domesle, Christian; Hergenhahn, Uwe; Förstel, Marko; Heber, Oded

    2010-10-01

    Imaging of photofragments from molecular ions after irradiation by soft x-ray photons has been realized at the ion beam infrastructure TIFF set up at the FLASH facility. Photodissociation of the two-electron system HeH+ at 38.7 eV revealed the electronic excitations and the charge-state ratios for the products of this process, reflecting the non-adiabatic dissociation dynamics through multiple avoided crossings among the HeH+ Rydberg potential curves. Dissociative ionization of the protonated water molecules H3O+ and H5O+2 at 90 eV revealed the main fragmentation pathways after the production of valence vacancies in these ionic species, which include a strong three-body channel with a neutral fragment (OH + H+ + H+) in H3O+ photolysis and a significant two-body fragmentation channel (H3O++ H2O+) in H5O+2 photolysis. The measurements yield absolute cross sections and fragment angular distributions. Increased precision and sensitivity of the technique were realized in recent developments, creating a tool for exploring x-ray excited molecular states under highly controlled target conditions challenging detailed theoretical understanding.

  20. Kinetics of the competitive reactions of isomerization and peptide bond cleavage at l-α- and d-β-aspartyl residues in an αA-crystallin fragment.

    PubMed

    Aki, Kenzo; Okamura, Emiko

    2017-01-01

    d-β-aspartyl (Asp) residue has been found in a living body such as aged lens crystallin, although l-α-amino acids are constituents in natural proteins. Isomerization from l-α- to d-β-Asp probably modulates structures to affect biochemical reactions. At Asp residue, isomerization and peptide bond cleavage compete with each other. To gain insight into how fast each reaction proceeds, the analysis requires the consideration of both pathways simultaneously and independently. No information has been provided, however, about these competitive processes because each reaction has been studied separately. The contribution of Asp isomers to the respective pathways has still been veiled. In this work, the two competitive reactions, isomerization and spontaneous peptide bond cleavage at Asp residue, were simultaneously observed and compared in an αA-crystallin fragment, S(51) LFRTVLD(58) SG(60) containing l-α- and d-β-Asp58 isomers. The kinetics showed that the formation of l- and d-succinimide (Suc) intermediate, as a first step of isomerization, was comparable at l-α- and d-β-Asp. Although l-Suc was converted to l-β-Asp, d-Suc was liable to return to the original d-β-Asp, the reverse reaction marked enough to consider d-β-Asp as apparently stable. d-β-Asp was also resistant to the peptide bond cleavage. Such apparent less reactivity is probably the reason for gradual and abnormal accumulation of d-β-Asp in a living body under physiological conditions. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

  1. Mycobacterium avium restriction fragment length polymorphism-IS IS1245 and the simple double repetitive element polymerase chain reaction typing method to screen genetic diversity in Brazilian strains.

    PubMed

    Sequeira, Patrícia Carvalho de; Fonseca, Leila de Souza; Silva, Marlei Gomes da; Saad, Maria Helena Féres

    2005-11-01

    Simple double repetitive element polymerase chain reaction (MaDRE-PCR) and Pvu II-IS1245 restriction fragment length polymorphism (RFLP) typing methods were used to type 41 Mycobacterium avium isolates obtained from 14 AIDS inpatients and 10 environment and animals specimens identified among 53 mycobacteria isolated from 237 food, chicken, and pig. All environmental and animals strains showed orphan patterns by both methods. By MaDRE-PCR four patients, with multiple isolates, showed different patterns, suggesting polyclonal infection that was confirmed by RFLP in two of them. This first evaluation of MaDRE-PCR on Brazilian M. avium strains demonstrated that the method seems to be useful as simple and less expensive typing method for screening genetic diversity in M. avium strains on selected epidemiological studies, although with limitation on analysis identical patterns except for one band.

  2. Discrimination of seven Anopheles species from San Pedro de Uraba, Antioquia, Colombia, by polymerase chain reaction-restriction fragment length polymorphism analysis of its sequences.

    PubMed

    Zapata, Mario A; Cienfuegos, Astrid V; Quirós, Oscar I; Quiñones, Martha L; Luckhart, Shirley; Correa, Margarita M

    2007-07-01

    Accurate identification of anopheline species is essential for vector incrimination and implementation of appropriate control strategies. Several anopheline species are considered important malaria vectors in Colombia; however, species determination is complicated by cryptic morphology and intra-individual variation. We describe polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of internal transcribed spacer 2 (ITS2) sequences for differentiation of seven Anopheles species collected in a locality in Antioquia, Colombia, with high levels of malaria transmission. Each of these seven species can be identified by unique AluI PCR-RFLP restriction patterns. Comparisons of morphologic identification with molecular identification of voucher specimens confirmed species designation for 886 wild-caught anophelines. This new method can be used as a diagnostic tool for discrimination of anopheline species of medical importance in this region, some of which have overlapping morphologic characters and for conducting complementary studies where rapid and accurate identification of large numbers of specimens is needed.

  3. Molecular authentication of 21 Korean artemisia species (Compositae) by polymerase chain reaction-restriction fragment length polymorphism based on trnL-F region of chloroplast DNA.

    PubMed

    Lee, Jeong Hoon; Lee, Jei Wan; Sung, Jung Sook; Bang, Kyong Hwan; Moon, Sung Gi

    2009-11-01

    The present study describes the molecular authentication of 21 Korean Artemisia species using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) technique based on the trnL-F sequences in chloroplast DNA. Five different banding patterns were generated from 21 Artemisia species using HinfI restriction enzyme. A. apiacea, A. keiskeana and A. sieversiana have specific banding patterns. The remaining 18 species had shared two banding patterns. Phylogenetic analysis based on trnL-F sequence variations showed results similar to PCR-RFLP banding patterns. It suggested that the trnL-F region does not have sufficient variations to identify the 21 Artemisia species. However, the specific banding patterns for A. apiacea, A. keiskeana and A. sieversiana can be utilized as a DNA marker for discriminating them from other Artemisia species. These markers will be also useful for developing A. apiacea, A. keiskeana and A. sieversiana into new medicine and food based on their efficacy.

  4. Polymerase chain reaction-restriction fragment length polymorphism method to distinguish three mealybug groups within the Planococcus citri-P. minor species complex (Hemiptera: Coccoidea: Pseudococcidae).

    PubMed

    Rung, A; Miller, D R; Scheffer, S J

    2009-02-01

    The mealybug species Planococcus citri (Risso) and Planococcus minor (Maskell) (Hemiptera: Coccoidea: Pseudococcidae) have special significance to U.S. quarantine and U.S. agriculture. Commonly intercepted at U.S. ports-of-entry, they are difficult to identify based on morphological characters. This study presents a molecular method for distinguishing P. citri, P. minor, and a genetically distinct group that is morphologically identical to P. citri, from Hawaii. This method uses polymerase chain reaction (PCR) followed by restriction fragment polymorphism analysis (RFLP) using the restriction enzymes BspH1, BsmH1, and HpH1. The resulting band patterns can be visualized in a 2% agarose gel and are sufficient to differentiate between the three entities mentioned above. PCR-RFLP diagnostics can be used for all life stages and is cheaper and faster than DNA sequencing.

  5. Neutron production in coincidence with fragments from the 4Ca+H reactions at Elab=357 and 565 A MeV

    NASA Astrophysics Data System (ADS)

    Tuvà, C.; Albergo, S.; Boemi, D.; Caccia, Z.; Chen, C.-X.; Costa, S.; Crawford, H. J.; Cronqvist, M.; Engelage, J.; Greiner, L.; Guzik, T. G.; Insolia, A.; Knott, C. N.; Lindstrom, P. J.; Mitchell, J. W.; Potenza, R.; Russo, G. V.; Soutoul, A.; Testard, O.; Tricomi, A.; Tull, C. E.; Waddington, C. J.; Webber, W. R.; Wefel, J. P.

    2000-04-01

    In the frame of the Transport Collaboration neutrons in coincidence with charged fragments produced in the 40Ca+H reaction at Elab=357 and 565 A MeV have been measured at the Heavy Ion Spectrometer System (HISS) facility of the Lawrence Berkeley National Laboratory, using the multifunctional neutron spectrometer MUFFINS. The detector covered a narrow angular range about the beam in the forward direction (0°-3.2°). In this contribution we report absolute neutron production cross sections in coincidence with charged fragments (10⩽Z⩽20). The neutron multiplicities have been estimated from the comparison between the neutron cross sections, in coincidence with the fragments, and the elemental cross sections. We have found evidence for a pre-equilibrium emission of prompt neutrons in superposition to a `slower' deexcitation of the equilibrated remnant by emission of nucleons and fragments, as already seen in the inclusive rapidity distributions.

  6. Neutron Production in Coincidence with Fragments from the {sup 40}Ca + H Reactions at E{sub lab} = 357 and 565 A MeV

    SciTech Connect

    Tuve, C.; Albergo, S.; Boemi, D.; Caccia, Z.; Chen, C.-X.; Costa, S.; Crawford, H.J.; Cronqvist, M.; Engelage, J.; Greiner, L.; Guzik, T.G.; Insolia, A.; Knott, C.N.; Lindstrom, P.J.; Mitchell, J.W.; Potenza, R.; Russo, G.V.; Soutoul, A.; Testard, O.; Tricomi, A.; Tull, C.E.; Waddington, C.J.; Webber, W.R.; Wefel, J.P.

    2000-12-31

    In the frame of the Transport Collaboration neutrons in coincidence with charged fragments produced in the {sup 40}Ca + H reaction at E{sub lab} = 357 and 565 AMeV have been measured at the Heavy Ion Spectrometer System (HISS) facility of the Lawrence Berkeley National Laboratory, using the multifunctional neutron spectrometer MUFFINS. The detector covered a narrow angular range about the beam in the forward direction (0? - 3.2?). In this contribution we report absolute neutron production cross sections in coincidence with charged fragments (10 {<=} Z {<=} 20). The neutron multiplicities have been estimated from the comparison between the neutron cross sections, in coincidence with the fragments, and the elemental cross sections. We have found evidence for a pre-equilibrium emission of prompt neutrons in superposition to a 'slower' deexcitation of the equilibrated remnant by emission of nucleons and fragments, as already seen in the inclusive rapidity distributions.

  7. Controlling Chemical Reactions by Short, Intense Mid-Infrared Laser Pulses: Comparison of Linear and Circularly Polarized Light in Simulations of ClCHO(+) Fragmentation.

    PubMed

    Shi, Xuetao; Thapa, Bishnu; Li, Wen; Schlegel, H Bernhard

    2016-02-25

    Enhanced mode selective fragmentation of oriented ClCHO(+) → Cl + HCO(+), H + ClCO(+), HCl(+) + CO with linear polarized intense mid-IR pulses was demonstrated in our previous computational study ( J. Phys. Chem. Lett. 2012 , 3 , 2541 ). Simulations of angle-dependent strong field ionization of ClCHO indicate the ionization rate in the molecular plane is nearly twice as large as perpendicular to the plane, suggesting a degree of planar alignment can be obtained experimentally for ClCHO(+), starting from neutral molecules. Classical trajectory calculations with a 4 cycle 7 μm laser pulse (peak intensity of 1.26 × 10(14) W/cm(2)) show that circularly polarized light with the electric field in the plane of the molecule deposits more energy and yields larger branching ratios for higher energy fragmentation channels than linearly polarized light with the same maximum field strength. These results suggest circularly polarized mid-IR pulses can not only achieve control on reactions but also provide an experimentally accessible implementation.

  8. Polymerase chain reaction-restriction fragment length polymorphism assays to distinguish Liriomyza huidobrensis (Diptera: Agromyzidae) from associated species on lettuce cropping systems in Italy.

    PubMed

    Masetti, Antonio; Luchetti, Andrea; Mantovani, Barbara; Burgio, Giovanni

    2006-08-01

    The pea leafminer, Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae), is a serious insect pest infesting open field lettuce plantings in northern Italy. In these cropping systems, it coexists with several other agromyzid species that have negligible economic importance on open field vegetables. The rapid detection of L. huidobrensis is crucial for effective management strategies, but the identification of agromyzids to species can be very difficult at adult as well at immature stages. In this study, a polymerase chain reaction (PCR)-restriction fragment length polymorphism assay is proposed to separate L. huidobrensis from Liriomyza bryoniae (Kaltenbach), Liriomyza trifolii (Burgess), and Chromatomyia horticola (Goureau), which usually occur in the same lettuce plantings. An approximately 1,031-bp region of the mitochondrial genome encompassing the 3' region of cytochrome oxidase I, the whole leucine tRNA, and all of the cytochrome oxidase II was amplified by PCR and digested using the enzymes PvuII and SnaBI separately. Both endonucleases cut the amplicons of L. huidobrensis in two fragments, whereas the original band was not cleaved in the other analyzed species. The presence of Dacnusa spp. DNA does not bias the assay, because the PCR conditions and the primer set here described do not amplify any tract of this endoparasitic wasp genome.

  9. NORMAL AND PATHOLOGICAL FRAGMENTATION OF RED BLOOD CELLS; THE PHAGOCYTOSIS OF THESE FRAGMENTS BY DESQUAMATED ENDOTHELIAL CELLS OF THE BLOOD STREAM; THE CORRELATION OF THE PEROXIDASE REACTION WITH PHAGOCYTOSIS IN MONONUCLEAR CELLS

    PubMed Central

    Doan, Charles A.; Sabin, Florence R.

    1926-01-01

    1. There is constantly some breaking down of red cells in the circulation by fragmentation. 2. The fragments of red cells, as well as whole red cells, are phagocytized and destroyed by clasmatocytes or endothelial phagocytes. 3. When there is an increase in fragmentation in abnormal or pathological states, desquamated endothelial cells of the blood stream, as well as the clasmatocytes of the tissues, increase proportionately and take in these fragments. These cells are to be distinguished from eosinophilic leucocytes by the nature of their granules, by the type of motility of the cells, and by a negative peroxidase test. 4. The desquamated endothelial cells, clasmatocytes, in the circulating blood are positive to the peroxidase test only when they have taken in positive material. 5. The monocytes show marked variations of the oxidase reaction in different species and to different techniques. With the Sato and Sekiya technique most monocytes of human blood are positive, while most of them in rabbit blood are negative, but both positive and negative reactions are found in both human and rabbit blood. PMID:19869165

  10. Fragmentation of displacement cascades into subcascades: A molecular dynamics study

    SciTech Connect

    Antoshchenkova, E.; Luneville, L.; Simeone, D.; Stoller, R. E.; Hayoun, M.

    2015-01-01

    The fragmentation of displacement cascades into subcascades in copper and iron has been investigated through the molecular dynamics technique. A two-point density correlation function has been used to analyze the cascades as a function of the primary knock-on (PKA) energy. This approach is used as a tool for detecting subcascade formation. The fragmentation can already be identified at the end of the ballistic phase. Its resulting evolution in the peak damage state discriminates between unconnected and connected subcascades. The damage zone at the end of the ballistic phase is the precursor of the extended regions that contain the surviving defects. A fractal analysis of the cascade exhibits a dependence on both the stage of the cascade development and the PKA energy. This type of analysis enables the minimum and maximum displacement spike energies together with the subcascade formation threshold energy to be determined. (C) 2014 Elsevier B.V. All rights reserved.

  11. Single Molecule Study on Incorporation Efficiency of DPO4 and Klenow Fragment to BPDE Adduct

    NASA Astrophysics Data System (ADS)

    Song, Lu; Yeh, Yin; Balhorn, Rod; Cosman, Monique

    2009-03-01

    DNA synthesis involving high fidelity A-family polymerases such as Klenow fragment is blocked by DNA adducts, while Y-family DNA polymerases such as Dpo4 can bypass the DNA adducts to resume DNA synthesis. So understanding the functional relationship between A-family and Y-family DNA polymerases in DNA replication and the mechanism of bypassing DNA adducts is of great help to explain the cause of mutagenesis. We introduce a flow cell on modified surface to study the incorporation efficiency of Dpo4 and Klenow fragments to benzo[a]pyrene-diol-epoxide (BPDE) adduct at single molecule level. Specifically, we anchor the labeled DNA onto the modified surface with adduct site open for nucleotide incorporation and flow the polymerases and labeled nucleotides into flow cell. With Total Internal Reflection Fluorescence Microscopy (TIRFM) we identify the incorporation of the nucleotides onto the anchored DNA template by identifying the co-localization of the template position and that of the labeled nucleotide. We further quantify the signal densities of the images obtained from the two different polymerases, thus examining whether incorporation reactions have been executed and quantifying the incorporation efficiency of the polymerases. We can also identify, on the specific adduct site, which nucleotide, if any, is incorporated by each of the two polymerases.

  12. Determining fragmentation dynamics through a study of neutron multiplicity at the NSCL

    NASA Astrophysics Data System (ADS)

    Stephenson, Sharon; Christ, Peter; Mazza, Maria; MoNA Collaboration

    2017-01-01

    In nuclear fragmentation reactions the number of neutrons and the excitation energy of the final fragment are related to the excitation energies of prefragments, which are produced in the reaction target but not directly observed. The MoNA Collaboration designed and performed an experiment to measure the number of neutrons in coincidence with charged projectile fragments to determine the excitation mechanisms of specific prefragments. All prior MoNA experimental campaigns concentrated on neutrons emitted from discrete levels in near dripline nuclei and treated any evaporation neutrons as an underlying background. This experiment capitalizes on those evaporation neutrons, focusing on sodium, neon and fluorine reaction products. For the experiment a 32Mg secondary beam with energy 86 MeV/u was incident on a Be reaction target. This target is upstream from the Sweeper, a superconducting dipole steering magnet with a bending angle of 43° and a vertical gap that permits forward-focused neutrons to get to the MoNA, the Modular Neutron Array. The rigidity of the Sweeper was varied during this experiment to increase the detection range. Analysis of the neutron-neutron hit distribution in coincidence with each sodium, neon, or fluorine charged fragment will be presented. This work was supported in part by the National Science Foundation Award 1613429 and the Howard Hughes Medical Institute Award 52007540.

  13. Synthetic Studies toward the C14-C29 Fragment of Mirabalin.

    PubMed

    Cornil, Johan; Echeverria, Pierre-Georges; Reymond, Sébastien; Phansavath, Phannarath; Ratovelomanana-Vidal, Virginie; Guérinot, Amandine; Cossy, Janine

    2016-09-16

    A convergent synthesis of one isomer of the C14-C29 fragment of mirabalin is disclosed. The key steps include a Marshall allenylation, a Mukaiyama aldol reaction and a Crimmins aldolization, which allow the control of 10 out of 25 stereogenic centers present in the molecule.

  14. Distinguishing Heterodera filipjevi and H. avenae using polymerase chain reaction-restriction fragment length polymorphism and cyst morphology.

    PubMed

    Yan, Guiping; Smiley, Richard W

    2010-03-01

    The cereal cyst nematodes Heterodera filipjevi and H. avenae impede wheat production in the Pacific Northwest (PNW). Accurate identification of cyst nematode species and awareness of high population density in affected fields are essential for designing effective control measures. Morphological methods for differentiating these species are laborious. These species were differentiated using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) of internal transcribed spacer (ITS)-ribosomal (r)DNA with up to six restriction endonucleases (TaqI, HinfI, PstI, HaeIII, RsaI, and AluI). The method was validated by inspecting underbridge structures of cyst vulval cones. Grid soil sampling of an Oregon field infested by both species revealed that H. filipjevi was present at most of the infested grid sites but mixtures of H. avenae and H. filipjevi also occurred. These procedures also detected and differentiated H. filipjevi and H. avenae in soil samples from nearby fields in Oregon and H. avenae in samples from Idaho and Washington. Intraspecific polymorphism was not observed within H. filipjevi or PNW H. avenae populations based on the ITS-rDNA. However, intraspecific variation was observed between H. avenae populations occurring in the PNW and France. Methods described here will improve detection and identification efficiencies for cereal cyst nematodes in wheat fields.

  15. Theoretical Analysis of the Fragmentation of (CO)5: A Symmetry-Allowed Highly Exothermic Reaction that Follows a Stepwise Pathway.

    PubMed

    Liu, Jiajun; Bao, Xiaoguang; Hrovat, David A; Borden, Weston Thatcher

    2015-12-04

    B3LYP and CCSD(T) calculations, using an aug-cc-pVTZ basis set, have been carried out on the fragmentation of 1,2,3,4,5-cyclopentanepentone, (CO)(5), to five molecules of CO. Although this reaction is calculated to be highly exothermic and is allowed to be concerted by the Woodward-Hoffmann rules, our calculations find that the D(5h) energy maximum is a multidimensional hilltop on the potential energy surface. This D(5h) hilltop is 16-20 kcal/mol higher in energy than a C(2) transition structure for the endothermic cleavage of (CO)(5) to (CO)(4) + CO and 11-15 kcal/mol higher than a C(s) transition structure for the loss of two CO molecules. The reasons for the very high energy of the D(5h) hilltop are discussed, and the geometries of the two lower energy transition structures are rationalized on the basis of mixing of the e(2)' HOMO and the a(2)″ LUMO of the hilltop.

  16. [Microclimate edge effects of evergreen broad-leaved forest fragments in Jinyun Mountain: a preliminary study].

    PubMed

    Yan, Min; Zhong, Zhangchen; Qiao, Xiuhong

    2006-01-01

    This paper studied the microclimate of continuous and fragmental evergreen broad-leaved forests in Jinyun Mountain by determining the horizontal gradient distribution of microclimate elements near forest edges. The results showed that there existed clear edge effects of microclimate in every edge of fragmental forests. The distinctions of maximum and minimum air temperature, photosynthetic active radiation, and minimum relative humidity between edge forest and interior forest were higher or greater, while that of maximum ground surface temperature was lower or smaller in dry season than in rain season. The edge effect was the smallest in the biggest fragmental patch, but the greatest in the smallest fragmental patch in interior forest.

  17. Physical organic studies of organometallic reactions

    SciTech Connect

    Bergman, Robert G.

    1981-01-01

    The mechanisms of reactions of organotransition metal complexes have only begun to be understood in detail during the last ten years. The complementary interaction of techniques and concepts developed earlier in studies of organic reaction mechanisms, with those commonly used in inorganic chetnistry, has played a crucial role in helping to elucidate organor.1etall.ic reaction mechanisms. A few systems in which this interaction has proved especially fruitful are discussed in this article.

  18. Taenia saginata: differential diagnosis of human taeniasis by polymerase chain reaction-restriction fragment length polymorphism assay.

    PubMed

    Nunes, Cáris Maroni; Dias, Ana Karina Kerche; Dias, Francisca Elda Ferreira; Aoki, Sérgio Moraes; de Paula, Henrique Borges; Lima, Luis Gustavo Ferraz; Garcia, José Fernando

    2005-08-01

    Speciation of Taenia in human stool is important because of their different clinical and epidemiological features. DNA analysis has recently become possible which overcomes the problems of differentiating human taeniid cestodes morphologically. In the present study, we evaluated PCR coupled to restriction fragment length polymorphism to differentiate Taenia solium from Taenia saginata eggs present in fecal samples from naturally infected patients. A different DraI-RFLP pattern: a two-band pattern (421 and 100 bp) for T. saginata and a three-band pattern (234, 188, and 99 bp) for T. solium was observed allowing the two species to be separated. The lower detection limit of the PCR-RFLP using a non-infected fecal sample prepared with a given number of T. saginata eggs was 34 eggs in 2 g stool sediment. The 521 bp mtDNA fragment was detected in 8 out of 12 Taenia sp. carriers (66.6%). Of these, three showed a T. solium pattern and five a T. saginata pattern.

  19. Direct Reactions studies at RIBF new facility

    NASA Astrophysics Data System (ADS)

    Motobayashi, Tohru

    2009-10-01

    The RIKEN RI Beam Factory (RIBF) is the firs realization of new-generation facilities with beams of unstable nuclei. It is based on heavy-ion primary beams accelerated to 345 MeV/nucleon for all elements up to uranium. When the goal intensity, 1 pμA, is reached, RIBF allows production of about thousand new isotopes with the yield higher than 1 particle par day. Since the RI beam energy after production by in-flight fission and/or projectile fragmentation is be around 200-300 MeV/nucleon, the direct reaction is one of the useful processes for spectroscopy of uncle very far from the stability. Several experiments were proposed and a few of them have been performed with intense (currently) ^48Ca primary beams. The ZeroDegree Spectrometer, which is already operational, can be used to identify the product of a direct reaction in inverse kinematics coupled with, for example, measurement of γ-rays from excited states in the product. Construction of SAMURAI, a large-acceptance spectrometer, has been started. Decays of unbound states or breakup products from various types of direct reaction will be measured in coincidence. Experimental and theoretical issues to be considered for the specific conditions in this new opportunity will be discussed together with brief overview of near-term research.

  20. Experimental determination of particle range and dose distribution in thick targets through fragmentation reactions of stable heavy ions.

    PubMed

    Inaniwa, Taku; Kohno, Toshiyuki; Tomitani, Takehiro; Urakabe, Eriko; Sato, Shinji; Kanazawa, Mitsutaka; Kanai, Tatsuaki

    2006-09-07

    In radiation therapy with highly energetic heavy ions, the conformal irradiation of a tumour can be achieved by using their advantageous features such as the good dose localization and the high relative biological effectiveness around their mean range. For effective utilization of such properties, it is necessary to evaluate the range of incident ions and the deposited dose distribution in a patient's body. Several methods have been proposed to derive such physical quantities; one of them uses positron emitters generated through projectile fragmentation reactions of incident ions with target nuclei. We have proposed the application of the maximum likelihood estimation (MLE) method to a detected annihilation gamma-ray distribution for determination of the range of incident ions in a target and we have demonstrated the effectiveness of the method with computer simulations. In this paper, a water, a polyethylene and a polymethyl methacrylate target were each irradiated with stable (12)C, (14)N, (16)O and (20)Ne beams. Except for a few combinations of incident beams and targets, the MLE method could determine the range of incident ions R(MLE) with a difference between R(MLE) and the experimental range of less than 2.0 mm under the circumstance that the measurement of annihilation gamma rays was started just after the irradiation of 61.4 s and lasted for 500 s. In the process of evaluating the range of incident ions with the MLE method, we must calculate many physical quantities such as the fluence and the energy of both primary ions and fragments as a function of depth in a target. Consequently, by using them we can obtain the dose distribution. Thus, when the mean range of incident ions is determined with the MLE method, the annihilation gamma-ray distribution and the deposited dose distribution can be derived simultaneously. The derived dose distributions in water for the mono-energetic heavy-ion beams of four species were compared with those measured with an

  1. Intranuclear cascade-percolation approach for protons and light fragments production in neon-niobium reactions at 400 and 800 MeV per nucleon

    SciTech Connect

    Montarou, G.; Marroncle, J.; Alard, J.P.; Augerat, J.; Bastid, N.; Charmensat, P.; Dupieux, P.; Fraysse, L.; Parizet, M.J.; Rahmani, A. ); Babinet, R.; Cavata, C.; Demoulins, M.; Fanet, H.; Gosset, J.; L'Hote, D.; Lemaire, M.C.; Lucas, B.; Poitou, J.; Valette, O. ); Brochard, F.; Gorodetzky, P.; Racca, C. ); Cugnon, J. )

    1993-06-01

    The results of intranuclear cascade calculations (ideal gas with two-body collisions and no mean field), complemented by a simple percolation procedure, are compared with experimental data on protons and light nuclear fragments ([ital d], [ital t], [sup 3]He, and [sup 4]He) measured in 400 and 800 MeV/nucleon Ne+Nb collisions using a large solid angle detector. The model reproduces quite well global experimental observables like nuclear fragment multiplicity distributions or production cross sections, and nuclear fragment to proton ratios. For rapidity distributions the best agreement occurs for peripheral reactions. Transverse momentum analysis confirms once again that the cascade, although being a microscopic approach, gives too small a collective flow, the best agreement being reached for [ital Z]=2 nuclear fragments. Nevertheless these comparisons are encouraging for further improvements of the model. Moreover, such an approach is easy to extend to any other models that could calculate the nucleon phase space distribution after the compression stage of the reaction, when light nuclear fragments emitted at large angles are constructed from percolation.

  2. Metallographic study of metallic fragment of lunar surface material

    NASA Technical Reports Server (NTRS)

    Mints, R. I.; Petukhova, T. M.; Ivanov, A. V.

    1974-01-01

    A high precision investigation of a metallic fragment from the lunar material returned by the Soviet Luna 16 automatic station revealed three characteristic temperature intervals with different kinetics of solid solution decomposition. The following were found in the structure of the iron-nickel-cobalt alloy: (1) delta-phase and alpha-ferrite of diffusional, displacement origin in the grain boundary and acicular forms; and (2) martensite of isothermal and athermal nature, acicular, lamellar, massive, and dendritic. The diversity of the shapes of structural constituents is associated with the effect on their formation of elastic distortions and various mechanisms of deformation relaxation processes.

  3. The Influence of Contour Fragmentation on Recognition Memory: An Event-Related Potential Study

    ERIC Educational Resources Information Center

    Brodeur, Mathieu B.; Debruille, J. Bruno; Renoult, Louis; Prevost, Marie; Dionne-Dostie, Emmanuelle; Buchy, Lisa; Lepage, Martin

    2011-01-01

    The present study was carried out to examine how the event-related potentials to fragmentation predict recognition success. Stimuli were abstract meaningless figures that were either complete or fragmented to various extents but still recoverable. Stimuli were first encoded as part of a symmetry discrimination task. In a subsequent recognition…

  4. Fragmentation of displacement cascades into subcascades: A molecular dynamics study

    DOE PAGES

    Antoshchenkova, E.; Luneville, L.; Simeone, D.; ...

    2015-01-01

    The fragmentation of displacement cascades into subcascades in copper and iron has been investigated through the molecular dynamics technique. A two-point density correlation function has been used to analyze the cascades as a function of the primary knock-on (PKA) energy. This approach is used as a tool for detecting subcascade formation. The fragmentation can already be identified at the end of the ballistic phase. Its resulting evolution in the peak damage state discriminates between unconnected and connected subcascades. The damage zone at the end of the ballistic phase is the precursor of the extended regions that contain the surviving defects.more » A fractal analysis of the cascade exhibits a dependence on both the stage of the cascade development and the PKA energy. This type of analysis enables the minimum and maximum displacement spike energies together with the subcascade formation threshold energy to be determined. (C) 2014 Elsevier B.V. All rights reserved.« less

  5. Improved atmospheric trace gas measurements with an aircraft-based tandem mass spectrometer: Ion identification by mass-selected fragmentation studies

    NASA Astrophysics Data System (ADS)

    Reiner, Thomas; MöHler, Ottmar; Arnold, Frank

    1998-12-01

    We have built and employed an aircraft-borne triple quadrupole mass spectrometer (TQMS) for fragmentation studies of mass-selected ions in the upper troposphere and lower stratosphere. The fragmentation studies included both ambient and artificially produced ions relevant for the measurement of atmospheric trace gases by ion molecule reaction mass spectrometry (IMRMS) and led to an unambiguous identification of the chemical composition of important ions used for IMRMS measurements. Among these are the product ions of ion molecule reactions of CO3-(H2O)n and H3O+(H2O)n ions with HNO3, SO2, acetone, HCN, and methyl cyanide. These reactions have been studied in the laboratory, and ions having the same masses as the expected product ions have been previously observed in atmospheric IMRMS spectra. The present fragmentation studies are the first to actually identify the chemical composition of these ions during aircraft measurements in the upper troposphere and lower stratosphere and demonstrate that these ions can reliably be used for atmospheric trace gas measurements. Furthermore, the fragmentation studies gave indications for the existence and the possible identification of previously unknown ions. Among these the tentative identification of CO3-H2O2 offers the possibility for sensitive measurements of H2O2 by IMRMS. The fragmentation studies were accompanied by IMRMS measurements of atmospheric trace gases using the TQMS. Altitude profiles of HNO3, SO2, and lower limits for H2O2 are shown.

  6. Characterization of fragment emission in {sup 20}Ne(7-10 MeV/nucleon)+{sup 12}C reactions

    SciTech Connect

    Dey, Aparajita; Bhattacharya, C.; Bhattacharya, S.; Kundu, S.; Banerjee, K.; Mukhopadhyay, S.; Gupta, D.; Bhattacharjee, T.; Banerjee, S. R.; Bhattacharyya, S.; Rana, T. K.; Basu, S. K.; Saha, R.; Krishan, K.; Mukherjee, A.; Bandopadhyay, D.; Beck, C.

    2007-09-15

    The inclusive energy distributions of the complex fragments (3{<=}Z{<=}7) emitted from the bombardment of {sup 12}C by {sup 20}Ne beams with incident energies between 145 and 200 MeV have been measured in the angular range 10 deg.{<=}{theta}{sub lab}{<=}50 deg. Damped fragment yields in all the cases have been found to have the characteristic of emission from fully energy equilibrated composites. The binary fragment yields are compared with the standard statistical model predictions. Whereas Li and Be fragments yields are in agreement with statistical-model calculations, enhanced yields of entrance channel fragments (5{<=}Z{<=}7) indicate the survival of orbiting-like process in {sup 20}Ne+{sup 12}C system at these energies.

  7. Fragmentation Patterns and Mechanisms of Singly and Doubly Protonated Peptoids Studied by Collision Induced Dissociation

    NASA Astrophysics Data System (ADS)

    Ren, Jianhua; Tian, Yuan; Hossain, Ekram; Connolly, Michael D.

    2016-04-01

    Peptoids are peptide-mimicking oligomers consisting of N-alkylated glycine units. The fragmentation patterns for six singly and doubly protonated model peptoids were studied via collision-induced dissociation tandem mass spectrometry. The experiments were carried out on a triple quadrupole mass spectrometer with an electrospray ionization source. Both singly and doubly protonated peptoids were found to fragment mainly at the backbone amide bonds to produce peptoid B-type N-terminal fragment ions and Y-type C-terminal fragment ions. However, the relative abundances of B- versus Y-ions were significantly different. The singly protonated peptoids fragmented by producing highly abundant Y-ions and lesser abundant B-ions. The Y-ion formation mechanism was studied through calculating the energetics of truncated peptoid fragment ions using density functional theory and by controlled experiments. The results indicated that Y-ions were likely formed by transferring a proton from the C-H bond of the N-terminal fragments to the secondary amine of the C-terminal fragments. This proton transfer is energetically favored, and is in accord with the observation of abundant Y-ions. The calculations also indicated that doubly protonated peptoids would fragment at an amide bond close to the N-terminus to yield a high abundance of low-mass B-ions and high-mass Y-ions. The results of this study provide further understanding of the mechanisms of peptoid fragmentation and, therefore, are a valuable guide for de novo sequencing of peptoid libraries synthesized via combinatorial chemistry.

  8. Study of Electron Ionization and Fragmentation of Non-hydrated and Hydrated Tetrahydrofuran Clusters

    NASA Astrophysics Data System (ADS)

    Neustetter, Michael; Mahmoodi-Darian, Masoomeh; Denifl, Stephan

    2017-05-01

    Mass spectroscopic investigations on tetrahydrofuran (THF, C4H8O), a common model molecule of the DNA-backbone, have been carried out. We irradiated isolated THF and (hydrated) THF clusters with low energy electrons (electron energy 70 eV) in order to study electron ionization and ionic fragmentation. For elucidation of fragmentation pathways, deuterated TDF (C4D8O) was investigated as well. One major observation is that the cluster environment shows overall a protective behavior on THF. However, also new fragmentation channels open in the cluster. In this context, we were able to solve a discrepancy in the literature about the fragment ion peak at mass 55 u in the electron ionization mass spectrum of THF. We ascribe this ion yield to the fragmentation of ionized THF clusters.

  9. Study of Electron Ionization and Fragmentation of Non-hydrated and Hydrated Tetrahydrofuran Clusters

    NASA Astrophysics Data System (ADS)

    Neustetter, Michael; Mahmoodi-Darian, Masoomeh; Denifl, Stephan

    2017-03-01

    Mass spectroscopic investigations on tetrahydrofuran (THF, C4H8O), a common model molecule of the DNA-backbone, have been carried out. We irradiated isolated THF and (hydrated) THF clusters with low energy electrons (electron energy 70 eV) in order to study electron ionization and ionic fragmentation. For elucidation of fragmentation pathways, deuterated TDF (C4D8O) was investigated as well. One major observation is that the cluster environment shows overall a protective behavior on THF. However, also new fragmentation channels open in the cluster. In this context, we were able to solve a discrepancy in the literature about the fragment ion peak at mass 55 u in the electron ionization mass spectrum of THF. We ascribe this ion yield to the fragmentation of ionized THF clusters.

  10. Energy release protection for pressurized systems. I - Review of studies into blast and fragmentation

    NASA Astrophysics Data System (ADS)

    Brown, S. J.

    1985-12-01

    Studies of blast and fragmentation hazards associated with a pressure system rupture are presented. Areas of concern related to blast hazards include the system energy (prior to its explosive failure), chemical characteristics of the media contained within a bursting pressure system, secondary explosions, and energy release. Such aspects of blast effect as height of the burst (in an above-the-ground explosion), dimensional effects of the explosive, multiple explosions, burning rate of the explosive, dynamic pressure, reflected pressure, and confinement (for explosions within an enclosed structure) are discussed. Also treated are hazards from fragments or missiles ejected (fragmentation hazards), including initial frament velocity, velocity retardation, range, blast-generated fragments (from adjacent structures), and media and soil ejection. Mathematical treatments and graphs representing the individual aspects of the blast and fragmentation phenomena are included.

  11. Fragmentation, labeling and biodistribution studies of KS1/4, a monoclonal antibody

    SciTech Connect

    Mohd, S.B.

    1987-01-01

    In this study, an IgG2a (KS1/4), a monoclonal antibody (MoAb) specific against a human lung adenocarcinoma (UCLA P-3) was successfully fragmented enzymatically to yield F(ab')/sub 2/ and Fab by using pepsin and papain, respectively. The kinetic of fragmentation of the MoAb was compared to that of human immunoglobulin G (IgG). A similar pattern of fragmentation was observed with both antibodies with a higher percentage yield of the F(ab')/sub 2/ and Fab obtained upon the fragmentation of the IgG by the enzymes. The KS1/4 and the two fragments were labeled with three different radionuclides, namely iodine-131, indium-111 and selenium-75. The radioiodination of the MoAb and the fragments was carried out by using a modified chloramine-T method. Radiometal labeling of the MoAb and the fragments with indium-111 was performed by using DTPA as a bifunctional chelating agent, while intrinsic labeling of the MoAb was done by culturing the hybridoma in the presence of /sup 75/Se-methionine. The biodistribution of the radiolabeled MoAb, F(ab')/sub 2/ and Fab fragments were performed by injecting the preparations intravenously into nude mice bearing human lung adenocarcinoma.

  12. Neutron production in coincidence with fragments from the 40Ca + H reaction at Elab=357A and 565A MeV

    NASA Astrophysics Data System (ADS)

    Tuve, C.; Albergo, S.; Boemi, D.; Caccia, Z.; Chen, C.-X.; Costa, S.; Crawford, H. J.; Cronqvist, M.; Engelage, J.; Greiner, L.; Guzik, T. G.; Knott, C. N.; Insolia, A.; Lindstrom, P. J.; Mitchell, J. W.; Potenza, R.; Russo, G. V.; Soutoul, A.; Testard, O.; Tricomi, A.; Tull, C. E.; Waddington, C. J.; Webber, W. R.; Wefel, J. P.

    1999-01-01

    Neutron production, in coincidence with fragments emitted in the 40Ca+H reaction at Elab=357A and 565A MeV, has been measured using a 3-module version of the multifunctional neutron spectrometer MUFFINS. The mean neutron multiplicities for neutrons detected in the angular range covered by MUFFINS (0°-3.2°) have been estimated from the comparison between the neutron cross sections, in coincidence with the fragments, and the elemental cross sections. We have found evidence for a preequilibrium emission of prompt neutrons in superposition to a ``slower'' deexcitation of the equilibrated remnant by emission of nucleons and fragments, as already seen in inclusive rapidity distributions. The energy dependence of the inclusive neutron production cross sections, measured in a previous work, is here interpreted as due to the stronger neutron focusing in the forward direction at the higher energy. Comparison with a BNV+phase space coalescence model is discussed.

  13. An Isoratio Method to Study Free Energy and Temperature Effects in Intermediate Mass Fragments Produced in Heavy-Ion Collisions

    NASA Astrophysics Data System (ADS)

    Ma, Chun-Wang; Qiao, Chun-Yuan; Ding, Tian-Tian; Niu, Fei; Song, Yi-Dan; Niu, Yi-Fei

    2016-07-01

    An isoratio method, i.e., the isotopic (isotonic) ratio among three isotopes (isotones), is proposed to study the free energy and temperature effects in the intermediate mass fragments produced in heavy-ion collisions. The parameterizations for the free energy of nucleus at low temperature, which have been proposed in the framework of the density functional theory using the SKM skymre interaction, are adopted to calculate the temperature-dependent free energy of fragment. By analyzing the measured yields of fragments in the 140A MeV 58,64Ni + 9Be reactions, it is verified that the free energy in the isoratio is almost the same for different reactions. A temperature-dependent pairing-energy is introduced into the parameterizations for free energy, which reveals that the weakened pairing energy at the low temperature accounts for the weakened or disappearing odd-even staggering in isoratio. Supported by the Program for Science and Technology Innovation Talents in Universities of Henan Province under Grant No. 13HASTIT046, the Creative Experimental Project of National Undergraduate Students (CEPNU201510476017)

  14. Laser enhanced chemical reaction studies

    NASA Astrophysics Data System (ADS)

    The relaxation of vibrationally excited pyrazine (E = 40,640/cm) by collisions which populate the high J tail (J = 58-82) of the vibrationless ground state (00(exp 0)0) of CO2 has been studied using tunable infrared diode lasers to probe the scattered CO2 molecules. The nascent rotational populations and translational recoil velocities for a series of rotational states in the high J tail of the 00(exp 0)0 level of CO2 were measured at five collision cell temperatures: 243, 263, 298, 339, and 364 K. Both the rate constants describing these V-R/T processes and the translational temperatures describing the recoiling CO2 molecules exhibit a very weak positive temperature dependence indicating that the high energy CO2 molecules must originate from near the center of the pre-collision energy distribution. Quantitative estimates of the actual amount of energy transferred in collisions between CO2 and vibrationally excited pyrazine, based on an angular momentum and translational energy exponential gap model of the cross section, indicate that delta E(total) can be as large as 7090/cm (approximately 20 kcal/mol). These experiments offer compelling evidence that these energy transfer events can indeed be classified as supercollisions since they involve unusually large, single collision energy transfer magnitudes; and despite their relative infrequency, they play a most important role in the collisional deactivation of vibrationally excited pyrazine by a CO2 bath.

  15. Production of new neutron-rich isotopes of heavy elements in fragmentation reactions of {sup 238}U projectiles at 1A GeV

    SciTech Connect

    Alvarez-Pol, H.; Benlliure, J.; Casarejos, E.; Cortina-Gil, D.; Fernandez-Dominguez, B.; Pereira, J.; Audouin, L.; Enqvist, T.; Schmidt, K.-H.; Yordanov, O.; Junghans, A. R.; Jurado, B.; Rejmund, F.

    2010-10-15

    The production of heavy neutron-rich nuclei has been investigated using cold-fragmentation reactions of {sup 238}U projectiles at relativistic energies. The experiment performed at the high-resolving-power magnetic spectrometer Fragment Separator at GSI made it possible to identify 40 new heavy neutron-rich nuclei: {sup 205}Pt, {sup 207-210}Au, {sup 211-216}Hg, {sup 214-217}Tl, {sup 215-220}Pb, {sup 219-224}Bi, {sup 223-227}Po, {sup 225-229}At, {sup 230,231}Rn, and {sup 233}Fr. The production cross sections of these nuclei were also determined and used to benchmark reaction codes that predict the production of nuclei far from stability.

  16. Giardia duodenalis in Damascus, Syria: Identification of Giardia genotypes in a sample of human fecal isolates using polymerase chain reaction and restriction fragment length polymorphism analyzing method.

    PubMed

    Skhal, Dania; Aboualchamat, Ghalia; Al Nahhas, Samar

    2016-02-01

    Giardia duodenalis is a common gastrointestinal parasite that infects humans and many other mammals. It is most prevalent in many developing and industrialized countries. G. duodenalis is considered to be a complex species. While no morphological distinction among different assemblages exist, it can be genetically differentiated into eight major assemblages: A to H. The aim of this study was to determine the genetic heterogeneity of G. duodenalis in human isolates (a study conducted for the first time in Syria). 40 fecal samples were collected from three different hospitals during the hot summer season of 2014. Extraction of genomic DNA from all Giardia positive samples (based on a microscopic examination) was performed using QIAamp DNA Stool Mini Kit. β-giardin gene was used to differentiate between different Giardia assemblages. The 514 bp fragment was amplified using the Polymerase Chain Reaction method, followed by digestion in HaeIII restriction enzyme. Our result showed that genotype A was more frequent than genotype B, 27/40 (67.5%); 4/40 (10%) respectively. A mixed genotype of A+B was only detected in 9 isolates (22.5%). This is the first molecular study performed on G. duodenalis isolates in Syria in order to discriminate among the different genotypes. Further expanded studies using more genes are needed to detect and identify the Giardia parasite at the level of assemblage and sub-assemblage.

  17. Analysis of the rDNA internal transcribed spacer region of the Fusarium species by polymerase chain reaction-restriction fragment length polymorphism

    PubMed Central

    ZARRIN, MAJID; GANJ, FARZANEH; FARAMARZI, SAMA

    2016-01-01

    The Fusarium species are a widely spread phytopathogen identified in an extensive variety of hosts. The Fusarium genus is one of the most heterogeneous fungi and is difficult to classify. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis is a useful method in detection of DNA polymorphism in objective sequences. The aim of the present study was to identify the phylogenetic associations and usefulness of the internal transcribed spacer (ITS) region as a genetic marker within the most clinically important strain of the Fusarium species. A total of 50 strains of Fusarium spp. were used in the study, including environmental, clinical and reference isolates. The primers ITS1 and ITS4 were used in the study. Two restriction enzymes, HaeIII and SmaI, were assessed for the digestion of PCR products. A PCR product of ~550-base pairs was generated for each Fusarium species. The digested products with HaeIII and SmaI demonstrated that the bands generated for the medically significant Fusarium species, including F. solani, F. oxysporum, F. verticillidea, F. proliferatum and F. fujikuri, have different restriction enzyme patterns. In conclusion, it appears that the PCR-RFLP method used in the present study produces a sufficient restriction profile for differentiation of the most medically significant Fusarium species. PMID:27073635

  18. Fungal Fragments in Moldy Houses: A Field Study in Homes in New Orleans and Southern Ohio

    PubMed Central

    Reponen, Tiina; Seo, Sung-Chul; Grimsley, Faye; Lee, Taekhee; Crawford, Carlos; Grinshpun, Sergey A.

    2007-01-01

    Smaller-sized fungal fragments (<1 μm) may contribute to mold-related health effects. Previous laboratory-based studies have shown that the number concentration of fungal fragments can be up to 500 times higher than that of fungal spores, but this has not yet been confirmed in a field study due to lack of suitable methodology. We have recently developed a field-compatible method for the sampling and analysis of airborne fungal fragments. The new methodology was utilized for characterizing fungal fragment exposures in mold-contaminated homes selected in New Orleans, Louisiana and Southern Ohio. Airborne fungal particles were separated into three distinct size fractions: (i) >2.25 μm (spores); (ii) 1.05–2.25 μm (mixture); and (iii) < 1.0 μm (submicrometer-sized fragments). Samples were collected in five homes in summer and winter and analyzed for (1→3)-β-D-glucan. The total (1→3)-β-D-glucan varied from 0.2 to 16.0 ng m−3. The ratio of (1→3)-β-D-glucan mass in fragment size fraction to that in spore size fraction (F/S) varied from 0.011 to 2.163. The mass ratio was higher in winter (average = 1.017) than in summer (0.227) coinciding with a lower relative humidity in the winter. Assuming a mass-based F/S-ratio=1 and the spore size = 3 μm, the corresponding number-based F/S-ratio (fragment number/spore number) would be 103 and 106, for the fragment sizes of 0.3 and 0.03 μm, respectively. These results indicate that the actual (field) contribution of fungal fragments to the overall exposure may be very high, even much greater than that estimated in our earlier laboratory-based studies. PMID:19050738

  19. Fungal fragments in moldy houses: A field study in homes in New Orleans and Southern Ohio

    NASA Astrophysics Data System (ADS)

    Reponen, Tiina; Seo, Sung-Chul; Grimsley, Faye; Lee, Taekhee; Crawford, Carlos; Grinshpun, Sergey A.

    Smaller-sized fungal fragments (<1 μm) may contribute to mold-related health effects. Previous laboratory-based studies have shown that the number concentration of fungal fragments can be up to 500 times higher than that of fungal spores, but this has not yet been confirmed in a field study due to lack of suitable methodology. We have recently developed a field-compatible method for the sampling and analysis of airborne fungal fragments. The new methodology was utilized for characterizing fungal fragment exposures in mold-contaminated homes selected in New Orleans, Louisiana and Southern Ohio. Airborne fungal particles were separated into three distinct size fractions: (i) >2.25 μm (spores), (ii) 1.05-2.25 μm (mixture), and (iii) <1.0 μm (submicrometer-sized fragments). Samples were collected in five homes in summer and winter and analyzed for (1→3)- β- D-glucan. The total (1→3)- β- D-glucan varied from 0.2 to 16.0 ng m -3. The ratio of (1→3)- β- D-glucan mass in fragment size fraction to that in spore size fraction ( F/ S) varied from 0.011 to 2.163. The mass ratio was higher in winter (average=1.017) than in summer (0.227) coinciding with a lower relative humidity in the winter. Assuming a mass-based F/ S-ratio=1 and the spore size=3 μm, the corresponding number-based F/ S-ratio (fragment number/spore number) would be 10 3 and 10 6, for the fragment sizes of 0.3 and 0.03 μm, respectively. These results indicate that the actual (field) contribution of fungal fragments to the overall exposure may be very high, even much greater than that estimated in our earlier laboratory-based studies.

  20. Total Syntheses, Fragmentation Studies, and Antitumor/Antiproliferative Activities of FR901464 and Its Low Picomolar Analog

    PubMed Central

    Albert, Brian J.; Sivaramakrishnan, Ananthapadmanabhan; Naka, Tadaatsu; Czaicki, Nancy L.

    2008-01-01

    FR901464 is a potent anticancer natural product that lowers the mRNA levels of oncogenes and tumor suppressor genes. In this article, we report a convergent enantioselective synthesis of FR901464, which was accomplished in 13 linear steps. Central to the synthetic approach was the diene-ene cross olefin metathesis reaction to generate the C6-C7 olefin without the use of protecting groups as the final step. Additional key reactions include a Zr/Ag-promoted alkynylation to set the C4 stereocenter, a mild and chemoselective Red-Al reduction, a reagent-controlled stereoselective Mislow-Evans-type [2,3]-sigmatropic rearrangement to install the C5 stereocenter, a Carreira asymmetric alkynylation to generate the C4′ stereocenter, and a highly efficient ring-closing metathesis-allylic oxidation sequence to form an unsaturated lactone. The decomposition pathways of FR901464's right fragment were studied under physiologically relevant conditions. Facile epoxide opening by β-elimination gave two enones, one of which could undergo dehydration via its hemiketal to form a furan. To prevent this decomposition pathway, a right fragment was then rationally designed and synthesized. This analog was 12 times more stable than the right fragment of the natural product. Using this more stable right fragment analog, an FR901464 analog, meayamycin, was then prepared in 13 linear steps. The inhibitions of human breast cancer MCF-7 cell proliferation by synthetic FR901464 and meayamycin were studied, and the GI50 values for these compounds were determined to be 1.1 nM and 10 pM, respectively. Thus, meayamycin is among the most potent anticancer small molecules that do not bind to either DNA or microtubule. PMID:17279752

  1. Theoretical Studies of Gas Phase Elementary Reactions

    DTIC Science & Technology

    2007-06-01

    molecule reaction dynamics is essential for understanding plasma dynamics effects and some of the optical radiation associated with the spacecraft...published as paper 9 of the publication List c. The mechanism of the ion-molecule reaction: N3÷ + 0O Air plasmas at elevated pressures are currently the...subject of intensive study for a variety of applications. Typical non-equilibrium plasmas have heavy particle temperatures below 1000 K and average

  2. Precursor Ion Scan Mode-Based Strategy for Fast Screening of Polyether Ionophores by Copper-Induced Gas-Phase Radical Fragmentation Reactions.

    PubMed

    Crevelin, Eduardo J; Possato, Bruna; Lopes, João L C; Lopes, Norberto P; Crotti, Antônio E M

    2017-04-04

    The potential of copper(II) to induce gas-phase fragmentation reactions in macrotetrolides, a class of polyether ionophores produced by Streptomyces species, was investigated by accurate-mass electrospray tandem mass spectrometry (ESI-MS/MS). Copper(II)/copper(I) transition directly induced production of diagnostic acylium ions with m/z 199, 185, 181, and 167 from α-cleavages of [macrotetrolides + Cu](2+). A UPLC-ESI-MS/MS methodology based on the precursor ion scan of these acylium ions was developed and successfully used to identify isodinactin (1), trinactin (2), and tetranactin (3) in a crude extract of Streptomyces sp. AMC 23 in the precursor ion scan mode. In addition, copper(II) was also used to induce radical fragmentation reactions in the carboxylic acid polyether ionophore nigericin. The resulting product ions with m/z 755 and 585 helped to identify nigericin in a crude extract of Streptomyces sp. Eucal-26 by means of precursor ion scan experiments, demonstrating that copper-induced fragmentation reactions can potentially identify different classes of polyether ionophores rapidly and selectively.

  3. Alpha resonant scattering for astrophysical reaction studies

    SciTech Connect

    Yamaguchi, H.; Kahl, D.; Nakao, T.; Wakabayashi, Y.; Kubano, S.; Hashimoto, T.; Hayakawa, S.; Kawabata, T.; Iwasa, N.; Teranishi, T.; Kwon, Y. K.; Binh, D. N.; Khiem, L. H.; Duy, N. G.

    2014-05-02

    Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. One of the methods to study them is the α resonant scattering using the thick-target method in inverse kinematics. Among the recent studies at CRIB, the measurement of {sup 7}Be+α resonant scattering is discussed. Based on the result of the experiment, we evaluated the contributions of high-lying resonances for the {sup 7}Be(α,γ) reaction, and proposed a new cluster band in {sup 11}C.

  4. An (e, 2e + ion) study of low-energy electron-impact ionization and fragmentation of tetrahydrofuran with high mass and energy resolutions

    SciTech Connect

    Ren, Xueguang Pflüger, Thomas; Weyland, Marvin; Baek, Woon Yoon; Rabus, Hans; Ullrich, Joachim; Dorn, Alexander

    2014-10-07

    We study the low-energy (E{sub 0} = 26 eV) electron-impact induced ionization and fragmentation of tetrahydrofuran using a reaction microscope. All three final-state charged particles, i.e., two outgoing electrons and one fragment ion, are detected in triple coincidence such that the momentum vectors and, consequently, the kinetic energies for charged reaction products are determined. The ionic fragments are clearly identified in the experiment with a mass resolution of 1 amu. The fragmentation pathways of tetrahydrofuran are investigated by measuring the ion kinetic energy spectra and the binding energy spectra where an energy resolution of 1.5 eV has been achieved using the recently developed photoemission electron source. Here, we will discuss the fragmentation reactions for the cations C{sub 4}H{sub 8}O{sup +}, C{sub 4}H{sub 7}O{sup +}, C{sub 2}H{sub 3}O{sup +}, C{sub 3}H{sub 6}{sup +}, C{sub 3}H{sub 5}{sup +}, C{sub 3}H{sub 3}{sup +}, CH{sub 3}O{sup +}, CHO{sup +}, and C{sub 2}H{sub 3}{sup +}.

  5. An (e, 2e + ion) study of low-energy electron-impact ionization and fragmentation of tetrahydrofuran with high mass and energy resolutions.

    PubMed

    Ren, Xueguang; Pflüger, Thomas; Weyland, Marvin; Baek, Woon Yoon; Rabus, Hans; Ullrich, Joachim; Dorn, Alexander

    2014-10-07

    We study the low-energy (E0 = 26 eV) electron-impact induced ionization and fragmentation of tetrahydrofuran using a reaction microscope. All three final-state charged particles, i.e., two outgoing electrons and one fragment ion, are detected in triple coincidence such that the momentum vectors and, consequently, the kinetic energies for charged reaction products are determined. The ionic fragments are clearly identified in the experiment with a mass resolution of 1 amu. The fragmentation pathways of tetrahydrofuran are investigated by measuring the ion kinetic energy spectra and the binding energy spectra where an energy resolution of 1.5 eV has been achieved using the recently developed photoemission electron source. Here, we will discuss the fragmentation reactions for the cations C4H8O(+), C4H7O(+), C2H3O(+), C3H6(+), C3H5(+), C3H3(+), CH3O(+), CHO(+), and C2H3(+).

  6. Evaluation of tooth-fragment reattachment: a clinical and laboratory study.

    PubMed

    Yilmaz, Yucel; Guler, Cigdem; Sahin, Hakan; Eyuboglu, Ozge

    2010-08-01

    To evaluate the restoration of fractured teeth by reattaching tooth fragment to its tooth remnant in a group of children and adolescents, and to compare the results with those of a laboratory study. The clinical study was conducted on 43 fractured incisors: 22 uncomplicated crown fractures (Group A) and 21 complicated crown fractures (Group B). The 43 incisal fragments: 23 were kept dry for 47 h and 20 were kept wet for 24 h by the patients before they were reattached. The fragments were kept in 0.9% saline solution for 30 min before reattachment. The fragments in Group A were reattached using a dentin bonding agent, a flowable and a hybrid resin composite, whereas the fragments in Group B were reattached to the tooth remnant after a pulpotomy was performed. The laboratory study was conducted on 56 extracted incisors. Teeth were divided equally into four groups: Group I - Uncomplicated crown fracture + wet medium; Group II - Uncomplicated crown fracture + dry medium; Group III - Complicated crown fracture + wet medium, and Group IV - Complicated crown fracture + dry medium. The fragments were then reattached in a manner that was similar to that used in the clinical study. The restored teeth were then re-fractured. All data were analyzed statistically. In the clinical study, the restored teeth were followed up for 2 years. Neither the type of trauma nor the storage medium had any significant effect on the survival, color, and bond strength of the restored teeth when assessed in the clinical and laboratory study. The color disharmony that was encountered initially in restored teeth resolved significantly on its own accord within 12 months after reattachment of the fragment. Fragment reattachment can be used to treat fractured teeth successfully in children and adolescents.

  7. Species identification of Malayan Gaur, Kedah-Kelantan and Bali cattle using polymerase chain reaction-restricted fragment length polymorphism.

    PubMed

    Romaino, S M N; Fazly-Ann, Z A; Loo, S S; Hafiz, M M; Hafiz, M D; Iswadi, M I; Kashiani, P; Rosli, M K A; Syed-Shabthar, S M F; Md-Zain, B M; Abas-Mazni, O

    2014-01-21

    Mitochondrial DNA (mtDNA) is a useful genetic marker that can be used for species identification. The cytochrome b (Cyt b) gene is a suitable mtDNA candidate gene for use in phylogenetic analyses due to its sequence variability, which makes it appropriate for comparisons at the subspecies, species, and genus levels. This study was conducted to develop a rapid molecular method for species identification of Malayan gaur (Bos gaurus hubbacki), Kedah-Kelantan (KK) (Bos indicus), and Bali (Bos javanicus) cattle in Malaysia. DNA was extracted from blood samples of 8 Malayan gaurs, 30 KK, and 28 Bali cattle. A set of both specific and universal primers for the Cyt b gene were used in PCR amplification. DNA sequences obtained were then analyzed using BioEdit and Restriction Mapper softwares. The PCR products obtained from Cyt b gene amplification were then subjected to restriction enzyme digestion. The amplification, using both specific and universal primers, produced a 154- and a 603-bp fragment, respectively, in all three species. Two restriction enzymes, NlaIV and SspI, were used to obtain specific restriction profiles that allowed direct identification of Malayan gaur, KK, and Bali cattle. Our findings indicate that all three species can be identified separately using a combination of universal primers and the restriction enzyme SspI.

  8. Rotational and neutron-hole states in {sup 43}S via the neutron knockout and fragmentation reactions

    SciTech Connect

    Riley, L. A.; Hosier, K. E.; Adrich, P.; Baugher, T. R.; Bazin, D.; Diget, C. A.; Weisshaar, D.; Brown, B. A.; Cook, J. M.; Gade, A.; Garland, D. A.; Glasmacher, T.; Ratkiewicz, A.; Siwek, K. P.; Cottle, P. D.; Kemper, K. W.; Tostevin, J. A.

    2009-09-15

    The recent assertion that shape coexistence occurs in the neutron-rich isotope {sup 43}S implies that a state observed at 940 keV in a previous study is a rotational excitation of the deformed ground state. Here we use results from two intermediate-energy reactions to demonstrate that this state--assigned an energy of 971 keV in the present work--is indeed a rotational state. This result strengthens the case for shape coexistence in {sup 43}S.

  9. Theoretical studies of chemical reaction dynamics

    SciTech Connect

    Schatz, G.C.

    1993-12-01

    This collaborative program with the Theoretical Chemistry Group at Argonne involves theoretical studies of gas phase chemical reactions and related energy transfer and photodissociation processes. Many of the reactions studied are of direct relevance to combustion; others are selected they provide important examples of special dynamical processes, or are of relevance to experimental measurements. Both classical trajectory and quantum reactive scattering methods are used for these studies, and the types of information determined range from thermal rate constants to state to state differential cross sections.

  10. a Study of Proton Induced Nuclear Fragmentation in the Threshold Region: 1 TO 20 GEV

    NASA Astrophysics Data System (ADS)

    Sangster, Thomas Craig

    This thesis contains the details of the experimental set-up and final results of BNL E-778. The experimental objective was to study proton induced nuclear fragmentation using an internal gas jet target facility that was specifically designed for this experiment and installed in the AGS main ring. The fragment telescopes were designed to measure a broad range of fragment charge (2 to 14) and kinetic energy (5 to 100 MeV). Using a mixed gas target (1% or 3% Xe with H(,2)), normalized fragment production cross sections were obtained by separately measuring p-p elastic production from the H(,2) component. Fragment production cross sections are observed to rise dramatically ((TURN) x 10) for incident proton energies between 1 and 10 GeV, while above 10 GeV, fragment production appears to be independent of the incident proton energy. The measured differential cross sections (above 10 GeV) are found to agree (within 20%) with the differential cross sections measured during a previous internal target experiment (E-591) conducted at FNAL, where the lowest available proton energies were 50 GeV. The measured fragment kinetic energy spectra (above 10 GeV) are fit with a functional form motivated by the observation that fragment production in an excited nuclear system is consistent with a critical phenomenon (a liquid -gas phase transition). The failure of this functional form at the lowest available incident energies (below 10 GeV) is interpreted as the observation of an additional fragment production mechanism. Recent theoretical and experimental evidence for an asymmetric fission process (binary decay), is used to modify the original functional form for the two-component spectra. It is concluded that, in the threshold region, two fragment production mechanisms are observed. Although insufficient information is available to uniquely separate the two components, certain features of the asymmetric fission mechanism are identified. The observed p-nucleus systematics are also

  11. Chemical reaction and dust formation studies in laboratory hydrocarbon plasmas.

    NASA Astrophysics Data System (ADS)

    Hippler, Rainer; Majumdar, Abhijit; Thejaswini, H. C.

    Plasma chemical reaction studies with relevance to, e.g., Titan's atmosphere have been per-formed in various laboratory plasmas [1,2]. Chemical reactions in a dielectric barrier discharge at medium pressure of 250-300 mbar have been studied in CH4 /N2 and CH4 /Ar gas mixtures by means of mass spectrometry. The main reaction scheme is production of H2 by fragmenta-tion of CH4 , but also production of larger hydrocarbons like Cn Hm with n up to 10 including formation of different functional CN groups is observed. [1] A. Majumdar and R. Hippler, Development of dielectric barrier discharge plasma processing apparatus for mass spectrometry and thin film deposition, Rev. Sci. Instrum. 78, 075103 (2007) [2] H.T. Do, G. Thieme, M. Frühlich, H. Kersten, and R. Hippler, Ion Molecule and Dust Particle Formation in Ar/CH4 , Ar/C2 H2 and Ar/C3 H6 Radio-frequency Plasmas, Contrib. Plasma Phys. 45, No. 5-6, 378-384 (2005)

  12. Fragmentation study of aminoalcohol-diterpenoid alkaloids by electrospray ionization time-of-flight mass spectrometry.

    PubMed

    Liu, Xiuxiu; Tang, Minghai; Wang, Lu; Chao, Ruobing

    2016-01-15

    Aminoalcohol-diterpenoid alkaloids were found to be a group of cardioactive substances in the lateral roots of Aconitum carmichaeli Debx. Studies on the fragmentation behaviors and features of these alkaloids in mass spectrometry would be important for their structural identification and in vivo metabolic research, which has not received much attention thus far. In this study, the fragmentation behaviors of 14 aminoalcohol-diterpenoid alkaloids were investigated by utilizing high-resolution time-of-flight tandem mass spectrometry. By analysis of the obtained MS(2) data, we summarized the fragmentation features of the corresponding alkaloids under different collision energy. The dissociation of functional groups from the skeleton was observed as the main fragmentation way in electrospray ionization (ESI) mode. The order of fragmentation sites was C1/C3 > C16 > C15 > C6 > N, with loss of one or more CH3OH, H2O, C2H4 (substituent on N atom) or CO (at C15 ) groups. The first systematic investigations on the fragmentation of aminoalcohol-diterpenoid alkaloids are described in this paper, setting the stage for an in-depth identification and study of the corresponding components in complex systems. Copyright © 2015 John Wiley & Sons, Ltd.

  13. A study of the collisional fragmentation problem using the Gamma distribution approximation.

    PubMed

    Kostoglou, M; Karabelas, A J

    2006-11-15

    The nonlinear fragmentation population balance formulation has been elevated in recent years from a prototype for studying nonlinear integro-differential equations to a vehicle for analyzing and understanding several physicochemical processes of technological interest. The so-called pure collisional fragmentation, which is the particular mode of nonlinear fragmentation induced by collisions between particles, is studied here. It is shown that the corresponding population balance equation admits large time asymptotic (self-similarity) solutions for homogeneous fragmentation and collision functions (kernels). The self-similar solutions are given in closed form for some simple kernels. Based on the shape of the self-similar solutions the method of moments with Gamma distribution approximation is employed for transient solution (from initial state to establishment of the asymptotic shape) of the collisional fragmentation equation. These solutions are presented for several sets of parameters and their behavior is discussed rather extensively. The present study is similar to the one has already been performed for the case of the much simpler linear fragmentation equation [G. Madras, B.J. McCoy, AIChE J. 44 (1998) 647].

  14. Study of laser fragmentation process of silver nanoparticles in aqueous media

    NASA Astrophysics Data System (ADS)

    Šmejkal, Petr; Pfleger, Jiří; Vlčková, Blanka

    2008-12-01

    Laser fragmentation of Ag nanoparticles in Ag hydrosol was studied by simultaneous measurements of the transmitted fluence of the incident laser beam and the time evolution of the surface plasmon extinction (SPE) spectra. The experiments showed that the laser fragmentation in a small volume of hydrosol proceeds during first 20 pulses and then reaches saturation. The value of the transmitted fluence corresponding to saturation increases with incident pulse fluence, but the impact of the first pulse applied to the hydrosols shows an optical limitation. Fluences above 303 mJ/cm2 cause the formation of less stable, aggregating nanoparticles, while fluences below 90 mJ/cm2 do not provide sufficient energy for efficient fragmentation. The interval of fluences between 90-303 mJ/cm2 is optimal for fragmentation, since stable hydrosols constituted by small, non-aggregated nanoparticles are formed.

  15. Electrospray mass spectral fragmentation study of N,N'-disubstituted imidazolium ionic liquids.

    PubMed

    Lesimple, Alain; Mamer, Orval; Miao, Weishi; Chan, Tak Hang

    2006-01-01

    The tandem positive electrospray mass spectrometry (ESMS(n)) fragmentation of ionic liquids incorporating the 1-methyl-imidazolium ring substituted on N(II) with an alkyl chain functionalized with an alcohol, carboxylic acid, or an iodobenzyl or iodobenzoyl ester is presented for the first time. The influence of chain length and function is studied. Esterified structures led to intense CID fragments lacking the imidazolium ring allowing full characterization of the ester moiety. Fragment ion compositions for this interesting and newly important class of compounds are established through accurate mass data and deuterium labeling. The presence of the cationic ring system produces intense even electron molecular cations in electrospray that undergo multiple stages of CID to yield fragments which often are radical cations. Unusual losses of methyl and hydrogen radicals are frequently noted.

  16. A simple and rapid nested polymerase chain reaction-restriction fragment length polymorphism technique for differentiation of pathogenic and nonpathogenic Leptospira spp.

    PubMed

    Djadid, Navid Dinparast; Ganji, Zahra Faghanzadeh; Gouya, Mohammad Mehdi; Rezvani, Mahmood; Zakeri, Sedigheh

    2009-03-01

    A rapid and specific nested polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) has been developed to detect and differentiate pathogenic and nonpathogenic Leptospira spp. Leptospiral genomic DNA was extracted from suspected human sera using an improved method of standard phenol-chloroform, and specific primers have been used to amplify 16S ribosomal RNA from all pathogenic and nonpathogenic Leptospira spp. The PCR products of all nonpathogenic species were digested with ApoI enzyme, but not pathogenic. To evaluate this assay, we analyzed 283 serum samples collected from suspected patients with leptospirosis. Nested PCR assay confirmed that 42 (14.8%) of 283 samples harbored Leptospira infection, and RFLP assay confirmed 38 (90.5%) of 42 and 4 (9.5%) of 42 positive cases had pathogenic and nonpathogenic Leptospira spp., respectively. Based on sequencing results, Leptospira interrogans, Leptospira kirschneri, and Leptospira wolffii and nonpathogenic Leptospira biflexa and Leptospira genomospecies 3 have been detected among analyzed samples. The nested PCR-RFLP assay developed in this study fulfills this requirement in the early stage of infection.

  17. Molecular identification of Candida species isolated from cases of neonatal candidemia using polymerase chain reaction-restriction fragment length polymorphism in a tertiary care hospital.

    PubMed

    Fatima, Akeela; Bashir, Gulnaz; Wani, Tehmeena; Jan, Abiroo; Kohli, Amrish; Khan, Mosin S

    2017-01-01

    Candida spp. is an emerging cause of bloodstream infections worldwide. Delay in speciation of Candida isolates by conventional methods and resistance to antifungal drugs in various Candida species are responsible for the increase in morbidity and mortality due to candidemia. Hence, the rapid identification of Candida isolates is very important for the proper management of patients with candidemia. The aim was to re-evaluate the identification of various Candida spp. by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) and to evaluate the accuracy, speed, and cost of phenotypic methodology versus PCR-RFLP. Hospital-based cross-sectional study. Ninety consecutive clinical isolates of seven Candida species, isolated from blood of neonates and identified by routine phenotypic methods, were re-evaluated using universal primers internal transcribed spacer 1 (ITS1) and ITS4 for PCR amplification and Msp I restriction enzyme for RFLP. Kappa test for agreement. The results of PCR-RFLP were 100% in agreement with those obtained using conventional phenotypic methods. Identification could be achieved within 3 work days by both the methods. Our routine methods proved to be cost effective than PCR-RFLP. We can continue with our routine phenotypic methods and PCR-RFLP can be used for periodic quality control or when conventional methods fail to identify a species.

  18. Determination of integron frequency by a polymerase chain reaction-restriction fragment length polymorphism method in multidrug-resistant Escherichia coli, which causes urinary tract infections.

    PubMed

    Fallah, Fatemeh; Karimi, Abdollah; Goudarzi, Mehdi; Shiva, Farideh; Navidinia, Masoumeh; Jahromi, Mana Hadipour; Sajadi Nia, Raheleh Sadat

    2012-12-01

    The purpose of this study was to determine the presence of integrons in Escherichia coli, which cause urinary tract infections, and to define the association between integrons and antimicrobial susceptibility. Susceptibility of 200 isolates from urine samples of patients suffering from urinary tract infections to 13 antibiotics was determined by the Kirby-Bauer disk diffusion method. The existence of class1 and 2 integrons in resistant isolates was assessed by polymerase chain reaction-restriction fragment length polymorphism and sequencing. Antibiotic resistance patterns were observed as follows: amoxicillin 78%, tetracycline 76.1%, co-trimoxazole 67.7%, cephalotin 60%, nalidixic acid 57.4%, chloramphenicol 49%, gentamicin 46.4%, ceftazidim 38.1%, ciprofloxacin 36.2%, nitrofurantoin 33.5%, amikacin 32.1%, norfloxacin 36.1%, and imipenem 27.1%. Of 200 isolates, 155 (77.5%) were multidrug resistant (MDR). The existence of integrons was confirmed in 50.3% of isolates. Three class 1 integron types, aadA2 being the most frequently found, and four class 2 integron types are described. Significant association between resistance to gentamicin, co-trimoxazole, cephalotin, ceftazidim, imipenem, chloramphenicol, and nalidixic acid with the existence of integrons was observed. Multidrug resistance suggests that the strategy for treatment of patients with E.coli infections needs to be revised. Furthermore, it was shown that integrons may be partly responsible for multidrug resistance. Imipenem and norfloxacin were the most effective antibiotics against isolates.

  19. Novel polymerase chain reaction-restriction fragment length polymorphism assay to determine internal transcribed spacer-2 group in the Chagas disease vector, Triatoma dimidiata (Latreille, 1811)

    PubMed Central

    Richards, Bethany; de la Rúa, Nicholas M; Monroy, Carlota; Stevens, Lori; Dorn, Patricia L

    2013-01-01

    Triatoma dimidiata is the most important Chagas disease insect vector in Central America as this species is primarily responsible for Trypanosoma cruzi transmission to humans, the protozoan parasite that causes Chagas disease. T. dimidiata sensu lato is a genetically diverse assemblage of taxa and effective vector control requires a clear understanding of the geographic distribution and epidemiological importance of its taxa. The nuclear ribosomal internal transcribed spacer 2 (ITS-2) is frequently used to infer the systematics of triatomines. However, oftentimes amplification and sequencing of ITS-2 fails, likely due to both the large polymerase chain reaction (PCR) product and polymerase slippage near the 5' end. To overcome these challenges we have designed new primers that amplify only the 3'-most 200 base pairs of ITS-2. This region distinguishes the ITS-2 group for 100% of known T. dimidiata haplotypes. Furthermore, we have developed a PCR-restriction fragment length polymorphism (RFLP) approach to determine the ITS-2 group, greatly reducing, but not eliminating, the number of amplified products that need to be sequenced. Although there are limitations with this new PCR-RFLP approach, its use will help with understanding the geographic distribution of T. dimidiata taxa and can facilitate other studies characterising the taxa, e.g. their ecology, evolution and epidemiological importance, thus improving vector control. PMID:23828007

  20. Comparative evaluation of impact strength of fragment bonded teeth and intact teeth: an in vitro study.

    PubMed

    Venugopal, L; Lakshmi, M Narasimha; Babu, Devatha Ashok; Kiran, V Ravi

    2014-06-01

    To test and compare the impact strength of fragment bonded teeth with that of intact teeth by using impact testing machine (pendulum type) as a mode of load. Forty extracted, maxillary, central incisors selected for this study (20 control group and 20 experimental group). In experimental group, teeth crowns were fractured with a microtome at 2.5 mm from mesioincisal angle cervically, fractured portion is attached to original crown portion with 3 M single bond dentin bonding agent and 3 M Z '100', composite resin. Impact strength of fragment bonded teeth and intact teeth tested with impact testing machine and compared. Mean impact strength of fragment bonded teeth (30.76 KJ/M(2) ) is not statistically significant deferent from mean impact strength of intact teeth (31.11 KJ/M(2) ). Mean impact strength of fragment bonded teeth is not statistically different with that of intact teeth. Hence, after fracture of teeth if it is restored with fragment reattachment by using 3 M single bond dentin bonding agent and 3 M Z '100' composite resin is having impact strength like that of intact teeth. How to cite the article: Venugopal L, Lakshmi MN, Babu DA, Kiran VR. Comparative evaluation of impact strength of fragment bonded teeth and intact teeth: An in vitro study. J Int Oral Health 2014;6(3):73-6.

  1. Neutrino-nucleus reactions based on recent structure studies

    SciTech Connect

    Suzuki, Toshio

    2015-05-15

    Neutrino-nucleus reactions are studied with the use of new shell model Hamiltonians, which have proper tensor components in the interactions and prove to be successful in the description of Gamow-Teller (GT) strengths in nuclei. The new Hamiltonians are applied to obtain new neutrino-nucleus reaction cross sections in {sup 12}C, {sup 13}C, {sup 56}Fe and {sup 56}Ni induced by solar and supernova neutrinos. The element synthesis by neutrino processes in supernova explosions is discussed with the new cross sections. The enhancement of the production yields of {sup 7}Li, {sup 11}B and {sup 55}Mn is obtained while fragmented GT strength in {sup 56}Ni with two-peak structure is found to result in smaller e-capture rates at stellar environments. The monopole-based universal interaction with tensor force of π+ρ meson exchanges is used to evaluate GT strength in {sup 40}Ar and ν-induced reactions on {sup 40}Ar. It is found to reproduce well the experimental GT strength in {sup 40}Ar.

  2. Laser Studies of Gas Phase Radical Reaction.

    DTIC Science & Technology

    1985-11-30

    1nai Irvest-aator Or.G. Hancock gn; FILE CO, Contr3ctor : Oxford University . Physical Chemistry Laboratory. South Parks Road.AD-A 193 689 Oxfor o~d...HIF spectrum and study of reaction of this and the CCI radical with atoms vi) sea;rchtrr; f(r FC) ’ndlict of the 0 *CF, reaction. OXFORD UNIVERSITY -. - SOUTH...0 Awtilability Codes I Avail ’and/or Dis Spcal0 Spoo OXFORD UNIVERSITY Tt SOUTH PARKS ROAD OXFCRD OXFORD � X3Z U.S. Army Contract DAJA45-85-C-0034

  3. Molecular Beam Studies of Low Energy Reactions.

    DTIC Science & Technology

    1983-03-31

    COMPLETING PORN . REPORT NUMBER 1 2. GOVT ACCESSION NO. S. RECIPIENT’S CATALOG NUMBER A D A Oaq J- 4. TITLE (And Subtitle) . TYPE OF REPORT & PERIOD COVERED...Gatlinburg, Tenn . in 1981. 2+ c) Studies were made of the charge transfer reaction Ar + Ar 4 2+ Ar + Ar at relative energies from 2 to 1000 eV. Reasons for

  4. First isomeric quadrupole moment measured in fragmentation reactions: The case of {sup 61}Fe{sup m}(9/2{sup +})

    SciTech Connect

    Vermeulen, N.; Yordanov, D. T.; Neyens, G.; Chamoli, S. K.; Hass, M.; Goldring, G.; Singh, B. S. Nara; Daugas, J. M.; Delaroche, J. P.; Girod, M.; Goutte, H.; Morel, P.; Perru, O.; Peru, S.; Roig, O.; Oliveira-Santos, F. de; Grevy, S.; Perrot, L.; Stefan, I.

    2007-05-15

    This paper demonstrates the feasibility of quadrupole moment measurements on isomeric levels populated in projectile fragmentation reactions. The neutron-rich {sup 61}Fe(9/2{sup +}) [E*= 861 keV, T{sub 1/2}= 239(5) ns] isomer was produced and spin aligned by the intermediate energy fragmentation of a {sup 64}Ni beam and implanted in a Cd single crystal. Its spectroscopic quadrupole moment |Q{sub s}|=41(6) e fm{sup 2} agrees with mean-field based calculations using the finite-range Gogny force, suggesting a moderately deformed shape characterized by an intrinsic charge quadrupole moment Q{sub 0}=-85 e fm{sup 2} or Q{sub 0}=+115 e fm{sup 2}. The present measurement paves the way for future determinations of isomeric quadrupole moments in more exotic nuclei.

  5. Studies on cryoprotectant toxicity to zebrafish (Danio rerio) ovarian tissue fragments.

    PubMed

    Anil, S; Ghafari, F; Zampolla, T; Rawson, D M; Zhang, T

    2011-01-01

    Cryopreservation of ovarian tissue is a viable alternative to cryopreservation of oocytes and embryos in many species but it has not been studied in fish. Selection of cryoprotectant is an important step in designing cryopreservation protocols. In order to identify the optimum cryoprotectant (CPA) in a suitable concentration for zebrafish ovarian tissue cryopreservation, studies on toxicities of five commonly used cryoprotectants methanol, ethanol, dimethyl sulfoxide (DMSO), ethylene glycol (EG) and propylene glycol (PG) were carried out. Experiments were conducted on ovarian tissue fragments consisting of stage I and stage II ovarian follicles. Ovarian tissue fragments were incubated in 90% L-15 medium (pH 9) containing 1-4M cryoprotectants for 30min at 22°C. Three different tests were used to assess ovarian tissue fragment viability: trypan blue (TB) staining, fluorescein diacetate (FDA) combined with propidium iodide (PI) staining and adenosine 5´- triphosphate (ATP) assay. Results from these tests showed that ATP assay was more sensitive than FDA+PI or TB staining for assessing cryoprotectant toxicity to follicles in tissue fragments. Methanol and ethanol were the least toxic cryoprotectants tested. Cryoprotectant toxicity increased in the order of methanol/ethanol, DMSO, PG and EG. Ethanol was used for zebrafish ovarian tissue for the first time and the results showed that the effect of methanol and ethanol on ovarian tissue fragments were comparable. As methanol has been shown to be the most effective cryoprotectant for zebrafish ovarian follicles in our laboratory, the use of ethanol will also be considered in assisting future freezing protocol design. The present study also showed that stage II ovarian follicles are more sensitive to cryoprotectant treatment than stage I follicles in tissue fragments. The results obtained in this study provided useful information for ovarian tissue fragment cryopreservation protocol design in the future.

  6. Photocross-Linked Peptide-Protein Complexes Analysis: A Comparative Study of CID and ETD Fragmentation Modes

    NASA Astrophysics Data System (ADS)

    Clavier, Séverine; Bolbach, Gérard; Sachon, Emmanuelle

    2015-06-01

    Protein-protein interactions are among the keys to organizing cellular processes in space and time. One of the only direct ways to identify such interactions in their cellular environment is to covalently bond the interacting partners to fix the interaction. Photocross-linking in living cells is thus a very promising technique. The feasibility of in cellulo photocross-linking reactions has been shown and mass spectrometry is a tool of choice to analyze photocross-linked proteins. However, the interpretation of the MS and MS/MS spectra of photocross-linked peptides remains one of the most important bottlenecks of the method and still limits its potential for large-scale applications (interactomics). Fundamental studies are still necessary to understand and characterize the fragmentation behavior of photocross-linked peptides. Here, we report the successful identification of the interaction sites in a well-characterized model of in vitro interaction between a protein and a peptide. We describe in detail the fragmentation pattern of these photocross-linked species in order to identify trends that could be generalized. In particular, we compare CID and ETD fragmentation modes (and HCD in a lesser extent), demonstrating the complementarity of both methods and the advantage of ETD for the analysis of photocross-linked species. The information should help further development of dedicated software to properly score MS/MS spectra of photocross-linked species.

  7. Friedel-Crafts dealkylation reaction mediated by a stereoselective proton transfer in the fragmentation of protonated cyclic indolyl α-amino esters.

    PubMed

    Cao, Xiaoji; Wang, Ye; Mo, Yawen; Wu, Liang; Mo, Weimin

    2016-07-15

    Chiral cyclic indolyl α-amino esters are valuable substructures of peptides and peptidomimetics. Systematically exploring the fragmentation behavior of the protonated cyclic indolyl α-amino esters by a combination of high-resolution high-energy collisional dissociation mass spectrometry, hydrogen-deuterium exchange experiments and density functional theory (DFT) calculations is useful for further understanding their intrinsic properties and the fragmentation mechanisms of peptidomimetics constructed with them. All high-resolution high-energy collisional dissociation tandem mass spectrometry experiments were carried out using electrospray ionization hybrid Quadrupole-Orbitrap mass spectrometry in positive ion mode. Only the labile hydrogens were exchanged with deuterium in hydrogen-deuterium exchange experiments. Theoretical calculations were carried out by the DFT method at the B3LYP level with the 6-311G(d,p) basis set in the Gaussian 03 package of programs. In the fragmentation of protonated cyclic indolyl α-amino esters, when the two labile hydrogens on the N(8) position are successively transferred to the C(3) and C(4) positions, a Friedel-Crafts dealkylation reaction takes place spontaneously, with concomitant formation of an ion-neutral complex of [cyclic N-sulfonyl ketimino esters/protonated indoles]. Direct separation of this complex formed the protonated indoles, while a stereoselective proton transfer between the two components in the complex gave rise to protonated cyclic N-sulfonyl ketimino esters, which coincided with the hydrogen-deuterium experiments. Using H/D exchange experiments combined with theoretical calculations, a Friedel-Crafts dealkylation reaction mediated by a stereoselective proton transfer in the [cyclic N-sulfonyl ketimino esters/protonated indoles] complex was proposed for the fragmentation of protonated cyclic indolyl α-amino esters in high-energy collisional dissociation tandem mass spectrometry for the first time. Copyright

  8. Laser Studies of Gas Phase Radical Reactions.

    DTIC Science & Technology

    1989-01-01

    Acremonium chrysogenum , was prepared according to the published procedure [6]. This fungal enzyme had a specific activity of 0.023 IUmg1, and was estimated to...Dist-lbitionj Avdielbiity Codes jAvail atidjor Dist 6a A-I . p -1- Laser Studies of Gas Phase Radical Reactions G. Hancock Physical Chemistry...some additional experiments concerning the formation of carbene radicals in liquid phase enzyme cleavage studies are described. Keywords Laser

  9. Strong enhancement of dynamical emission of heavy fragments in the neutron-rich {sup 124}Sn+{sup 64}Ni reaction at 35A MeV

    SciTech Connect

    Russotto, P.; Amorini, F.; Cavallaro, S.; Di Toro, M.; Giustolisi, F.; Porto, F.; Rizzo, F.; De Filippo, E.; Pagano, A.; Cardella, G.; Lanzano, G.; Papa, M.; Pirrone, S.; Piasecki, E.; Auditore, L.; Trifiro, A.; Trimarchi, M.

    2010-06-15

    A quantitative comparison is made between the absolute cross sections associated with statistical and dynamical emission of heavy fragments in the {sup 124}Sn+{sup 64}Ni and {sup 112}Sn+{sup 58}Ni collisions experimentally investigated at 35A MeV beam energy using the multidetector CHIMERA. The result shows that the dynamical process is about twice as probable in the neutron-rich {sup 124}Sn+{sup 64}Ni system as in the {sup 112}Sn+{sup 58}Ni neutron-poor one. This unexpected and significant difference indicates that the reaction mechanism is strongly dependent on the entrance-channel isospin (N/Z) content.

  10. Response of DNA fragments to potentiometric sensors studied using HPLC.

    PubMed

    Nagels, Luc J; Everaert, Joseph; Bohets, Hugo; Del Favero, Jurgen; Goossens, Dirk; Robbens, Johan; Pietraszkiewicz, Marek; Pietraszkiewicz, Oksana

    2007-08-01

    Potentiometric sensors are studied as viable candidates for the construction of high throughput DNA arrays. For preliminary investigations, such sensors were used in an HPLC setup in the present work. This avoided errors due to ionic contaminants or additives in the commercial samples. The oligonucleotides dT(10), dT(20) and dT(30) were used as test substances. The potentiometric sensors were of the coated wire type, containing PVC, DOP, MTDDACl and a synthetic podand urea receptor. The HPLC system consisted of a reversed phase column eluted with a phosphate buffer, triethylammoniumacetate (TEAA), and an acetonitrile gradient. Molar responses and sensitivities increased with increasing chain length of oligonucleotides, yielding detection limits as low as 10(-6)M (dT(30), injected concentration). The slopes of the calibration graphs were at least 23 mV/decade (dT(10)), which was much higher than expected. The results are discussed in view of the potential use of this sensor type in high throughput microarrays.

  11. Vibration from freight trains fragments sleep: A polysomnographic study

    PubMed Central

    Smith, Michael G.; Croy, Ilona; Hammar, Oscar; Persson Waye, Kerstin

    2016-01-01

    As the number of freight trains on railway networks increases, so does the potential for vibration exposure in dwellings nearby to freight railway lines. Nocturnal trains in particular are of particular importance since night-time exposure may interfere with sleep. The present work investigates the impact of vibration and noise from night-time freight trains on human sleep. In an experimental polysomnographic laboratory study, 24 young healthy volunteers with normal hearing were exposed to simulated freight pass-bys with vibration amplitudes of 0.7 and 1.4 mm/s either 20 or 36 times during the night. Stronger vibrations were associated with higher probabilities of event-related arousals and awakenings (p < 0.001), and sleep stage changes (p < 0.05). Sleep macrostructure was most affected in high vibration nights with 36 events, with increased wakefulness (p < 0.05), reduced continual slow wave sleep (p < 0.05), earlier awakenings (p < 0.05) and an overall increase in sleep stage changes (p < 0.05). Subjects reported sleep disturbance due to vibration (F(4,92) = 25.9, p < 0.001) and noise (F(4,92) = 25.9, p < 0.001), with the number of trains having an effect only for the 0.7 mm/s condition (p < 0.05). The findings show that combined vibration and noise from railway freight affects the natural rhythm of sleep, but extrapolation of significance for health outcomes should be approached with caution. PMID:27090401

  12. Vibration from freight trains fragments sleep: A polysomnographic study.

    PubMed

    Smith, Michael G; Croy, Ilona; Hammar, Oscar; Persson Waye, Kerstin

    2016-04-19

    As the number of freight trains on railway networks increases, so does the potential for vibration exposure in dwellings nearby to freight railway lines. Nocturnal trains in particular are of particular importance since night-time exposure may interfere with sleep. The present work investigates the impact of vibration and noise from night-time freight trains on human sleep. In an experimental polysomnographic laboratory study, 24 young healthy volunteers with normal hearing were exposed to simulated freight pass-bys with vibration amplitudes of 0.7 and 1.4 mm/s either 20 or 36 times during the night. Stronger vibrations were associated with higher probabilities of event-related arousals and awakenings (p < 0.001), and sleep stage changes (p < 0.05). Sleep macrostructure was most affected in high vibration nights with 36 events, with increased wakefulness (p < 0.05), reduced continual slow wave sleep (p < 0.05), earlier awakenings (p < 0.05) and an overall increase in sleep stage changes (p < 0.05). Subjects reported sleep disturbance due to vibration (F(4,92) = 25.9, p < 0.001) and noise (F(4,92) = 25.9, p < 0.001), with the number of trains having an effect only for the 0.7 mm/s condition (p < 0.05). The findings show that combined vibration and noise from railway freight affects the natural rhythm of sleep, but extrapolation of significance for health outcomes should be approached with caution.

  13. Investigating the ocular temperature rise during femtosecond laser lens fragmentation: an in vitro study.

    PubMed

    Mencucci, Rita; Matteoli, Sara; Corvi, Andrea; Terracciano, Luca; Favuzza, Eleonora; Gherardini, Stefano; Caruso, Filippo; Bellucci, Roberto

    2015-12-01

    To investigate the trend of temperature variation during lens fragmentation simulated by a femtosecond laser on an in vitro eye model. In our experimental study, a convex cylinder of gelatinous material, usually employed in femtosecond laser calibration, was used to simulate both an anterior segment and a crystalline lens during fragmentation performed with the Victus femtosecond laser (Technolas Perfect Vision GmbH, Germany; Bausch + Lomb Incorporated, USA). Two radiated energies (7000 nJ and 9000 nJ) and three cutting patterns (crosses, circles and cross + circle) were applied. Trends of temperature variation as a function of time were obtained using a T-type thermocouple. The maximum value of temperature rise during lens fragmentation ranged from 3.53 to 5.13 °C; the rise was directly proportional to the intensity of the radiated energy (7000 nJ or 9000 nJ) and the cutting pattern performed. This behavior was experimentally represented by an asymmetric function with a characteristic bell curve shape, whereas it was mathematically described by a transport diffusive model. Since the temperature rise at the fragmentation volume base resulted to be around 5 °C in our in vitro study, lens fragmentation performed using the Victus femtosecond laser might be considered safe form a thermal point of view.

  14. Tone Induced Sleep Fragmentation in Persons with Alzheimer’s Disease: A Feasibility Study

    PubMed Central

    Richards, Kathy C.; Smith-Olinde, Laura; Roberson, Paula K.; Sullivan, Dennis H.

    2010-01-01

    Sleep fragmentation increases as Alzheimer’s disease (AD) progresses and its effects on cognition, specifically vigilant attention, are profoundly important because vigilant attention is thought to be the first step in memory acquisition. To our knowledge, no one has experimentally studied the effect of sleep fragmentation on vigilant attention in persons with AD. Therefore, this study piloted an experimental method using sound (tones produced by an audiometer) to induce sleep fragmentation. Participants enrolled in the University of Arkansas for Medical Sciences Memory Research Center (MRC) (n = 4) underwent one night of undisturbed and one of fragmented sleep. We found that 100% of participants were able to tolerate the earphone needed for the tone-induced sleep fragmentation (TISF) method, and we were able to score awakenings in real time. However, only 50% of tones produced awakenings. The findings suggest that this experimental method is feasible for use in persons with mild AD. Based on the results we will increase the duration, intensity, and frequency of tones delivered for optimal result. PMID:19617235

  15. Comparison of clustering effects in 12C fragmentation among p+12C, α+12C, and 14N+12C reactions: Excitation of α-cluster degrees of freedom in nuclear collisions

    NASA Astrophysics Data System (ADS)

    Takemoto, Hiroki; Horiuchi, Hisashi; Ono, Akira

    1998-02-01

    We examine 12C fragmentation in p+12C, α+12C, and 14N+12C reactions using antisymmetrized molecular dynamics. We compare 12C fragmentation among the above three kinds of reactions and find that the alpha-clustering effect in 12C fragmentation depends on the projectile and also on the incident energy. In proton induced reactions 4He fragments are scarcely produced at the early stage of the reaction in a wide range of incident energy. On the other hand, in α and 14N induced reactions many 4He fragments are produced during the dynamical stage at a lower incident energy but fewer 4He fragments are produced with increasing incident energy. We indicate that this abundance of 4He fragments at a lower incident energy in α and 14N induced reactions is due to the excitation of 12C to states with an excitation energy of 7-15 MeV which have the alpha-cluster structure. We see that the upper limit of the incident energy which gives rise to the dynamical production of 4He fragments is lower in the α induced reaction than in the 14N induced reaction. We show that the excitation to the clustering states is caused by the mean field from the projectile and that nucleon-nucleon collisions work to destroy this excitation. We will see that the disappearance of the excitation to the clustering states at high incident energies is partly due to the weakened effect of the mean field of the projectile and partly due to the strengthened effect of nucleon-nucleon collision processes.

  16. Preliminary study of analyzing mucosal human papillomaviruses in cutaneous warts by restriction fragment mass polymorphism.

    PubMed

    Park, So Eun; Ha, Jae Won; Kim, Chul Woo; Kim, Sang Seok

    2017-08-03

    Cutaneous human papillomavirus (HPV) types 1, 2, 4, 7 and 57 are reportedly found in cutaneous warts. However, there are few reports that have investigated the prevalence of mucosal HPV types in cutaneous warts. The aim of this study is to investigate the prevalence of mucosal HPV types in patients with cutaneous warts and to determine any association between HPV types and patient characteristics. We analyzed 62 wart samples that were taken from patients who were diagnosed with cutaneous warts, and 30 normal skin samples were used as negative control. We recorded the following characteristics: sex, age, type of warts, duration of warts, number of warts and patient's immune status. A matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS)-based restriction fragment mass polymorphism (RFMP) assay was used for HPV genotyping. Of the total 62 wart samples, 50 samples (81.6%) were positive for HPV genotypes. All of the negative controls (30 samples) using normal skin showed negative reaction. Mucosal HPV types (49 samples, 84.4%) were highly detected, and high- or probable high-risk HPV types (39 samples, 67.2%) were more common than lower risk HPV types (10 samples, 17.2%). A statistically significant association was observed between sex, age, duration of warts and the risk of HPV types. To the best of our knowledge, this is the first study to use the RFMP assay to analyze cutaneous wart-associated mucosal HPV types. The high prevalence of high-risk and probable high-risk HPV in this study is of great significance. © 2017 Japanese Dermatological Association.

  17. FALP and CRESU studies of ionic reactions

    NASA Astrophysics Data System (ADS)

    Rowe, B. R.; Canosa, A.; Le Page, V.

    1995-11-01

    Results obtained from the study of ionic reactions at the University of Rennes are reviewed. A brief description of the apparatus available in our laboratory is given. The historical evolution of the flowing afterglow device is emphasized as it is directly connected to one of the major puzzling questions in dissociative recombination studies: what is the rate coefficient for the dissociative recombination of H3+ in its ground state? Special attention is given to the dissociative recombination process which until recently was the main topic studied in Rennes. A compilation of our measurements of branching ratios and rate coefficients is presented. Results from other authors are also outlined with particular attention paid to H3+. Electron attachment and ion/molecule reactions studied with the flowing afterglow Langmuir probe mass spectrometer are presented. The first results of ion/molecule reactions at very low temperatures have been recently obtained with the CRESU apparatus available in Rennes. Comparison with measurements carried out in Meudon at lower pressures is made and discussed.

  18. Identification of Pork Contamination in Meatballs of Indonesia Local Market Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) Analysis.

    PubMed

    Erwanto, Yuny; Abidin, Mohammad Zainal; Sugiyono, Eko Yasin Prasetyo Muslim; Rohman, Abdul

    2014-10-01

    This research applied and evaluated a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using cytochrome b gene to detect pork contamination in meatballs from local markets in Surabaya and Yogyakarta regions, Indonesia. To confirm the effectiveness and specificity of this fragment, thirty nine DNA samples from different meatball shops were isolated and amplified, and then the PCR amplicon was digested by BseDI restriction enzyme to detect the presence of pork in meatballs. BseDI restriction enzyme was able to cleave porcine cytochrome b gene into two fragments (131 bp and 228 bp). Testing the meatballs from the local market showed that nine of twenty meatball shops in Yogyakarta region were detected to have pork contamination, but there was no pork contamination in meatball shops in Surabaya region. In conclusion, specific PCR amplification of cytochrome b gen and cleaved by BseDI restriction enzymes seems to be a powerful technique for the identification of pork presence in meatball because of its simplicity, specificity and sensitivity. Furthermore, pork contamination intended for commercial products of sausage, nugget, steak and meat burger can be checked. The procedure is also much cheaper than other methods based on PCR, immunodiffusion and other techniques that need expensive equipment.

  19. A specific polymerase chain reaction based on the gyrB gene sequence and subsequent restriction fragment length polymorphism analysis of Pasteurella pneumotropica isolates from laboratory mice.

    PubMed

    Hayashimoto, Nobuhito; Ueno, Masami; Takakura, Akira; Itoh, Toshio

    2007-03-01

    For a molecular identification and typing tool, we developed a specific polymerase chain reaction (PCR) based on the gyrB gene sequence and a subsequent restriction fragment length polymorphism (RFLP) analysis using the products amplified from the specific PCR to facilitate discrimination of biotypes of Pasteurella pneumotropica from laboratory mice. Appropriate PCR products, a 1039-basepair fragment for biotype Jawetz and a 1033-basepair fragment for biotype Heyl, were amplified by use of the primers CZO-1 and NJO-2 from all 105 P. pneumotropica isolates tested and the 2 reference strains but not from other bacterial species tested. MspI digestion of PCR-generated products showed 3 RFLP patterns among the 105 isolates, and these patterns correlated with the biotype of the isolate (RFLP pattern 1, biotype Jawetz; RFLP pattern 2, biotype Heyl; and RFLP pattern 3, biotype Jawetz with Beta-hemolytic activity). Our procedure identifies and biotypes isolates of P. pneumotropica from laboratory mice, using simple PCR and enzymatic restriction techniques. Therefore, this procedure is useful as a rapid identification and biotyping tool for isolates of P. pneumotropica from laboratory mice.

  20. Identification of Pork Contamination in Meatballs of Indonesia Local Market Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) Analysis

    PubMed Central

    Erwanto, Yuny; Abidin, Mohammad Zainal; Sugiyono, Eko Yasin Prasetyo Muslim; Rohman, Abdul

    2014-01-01

    This research applied and evaluated a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using cytochrome b gene to detect pork contamination in meatballs from local markets in Surabaya and Yogyakarta regions, Indonesia. To confirm the effectiveness and specificity of this fragment, thirty nine DNA samples from different meatball shops were isolated and amplified, and then the PCR amplicon was digested by BseDI restriction enzyme to detect the presence of pork in meatballs. BseDI restriction enzyme was able to cleave porcine cytochrome b gene into two fragments (131 bp and 228 bp). Testing the meatballs from the local market showed that nine of twenty meatball shops in Yogyakarta region were detected to have pork contamination, but there was no pork contamination in meatball shops in Surabaya region. In conclusion, specific PCR amplification of cytochrome b gen and cleaved by BseDI restriction enzymes seems to be a powerful technique for the identification of pork presence in meatball because of its simplicity, specificity and sensitivity. Furthermore, pork contamination intended for commercial products of sausage, nugget, steak and meat burger can be checked. The procedure is also much cheaper than other methods based on PCR, immunodiffusion and other techniques that need expensive equipment. PMID:25178301

  1. Identification of raw and heat-processed meats from game bird species by polymerase chain reaction-restriction fragment length polymorphism of the mitochondrial D-loop region.

    PubMed

    Rojas, M; González, I; Fajardo, V; Martín, I; Hernández, P E; García, T; Martín, R

    2009-03-01

    Polymerase chain reaction-RFLP analysis has been applied to the identification of meats from quail (Coturnix coturnix), pheasant (Phasianus colchicus), red-legged partridge (Alectoris rufa), chukar partridge (Alectoris chukar), guinea fowl (Numida meleagris), capercaillie (Tetrao urogallus), Eurasian woodcock (Scolopax rusticola), and woodpigeon (Columba palumbus). Polymerase chain reaction amplification was carried out using a set of primers flanking a conserved region of approximately 310 bp from the mitochondrial D-loop region. Restriction site analysis based on sequence data from this DNA fragment permitted the selection of HinfI, MboII, and Hpy188III endonucleases for species identification. The restriction profiles obtained when amplicons were digested with the chosen enzymes allowed the unequivocal identification of all game bird species analyzed. Consistent results were obtained with both raw and heat-processed meats.

  2. Detection of beta-globin gene mutations among Kelantan Malay thalassaemia patients by polymerase chain reaction restriction fragment length polymorphism.

    PubMed

    Rozitah, R; Nizam, M Z; Nur Shafawati, A R; Nor Atifah, M A; Dewi, M; Kannan, T P; Ariffin, N; Norsarwany, M; Setianingsih, I; Harahap, A; Zilfalil, B A

    2008-12-01

    Beta-thalassaemia major is an autosomal recessive disorder that results in severe microcytic, hypochromic, haemolytic anaemia among affected patients. Beta-thalassaemia has emerged as one of the most common public health problems in Malaysia, particularly among Malaysian Chinese and Malays. This study aimed to observe the spectrum of mutations found in Kelantan Malay beta-thalassaemia major patients who attended the Paediatrics Daycare Unit, Hospital Universiti Sains Malaysia, Kelantan, Malaysia, the data of which was being used in establishing the prenatal diagnosis in this Human Genome Centre. This was a cross-sectional study conducted with 35 Kelantan Malay beta-thalassaemia major patients. DNA was extracted from the blood collected from the patients and subjected to polymerase chain reaction (PCR) amplification. Six restriction enzymes were used to digest the PCR products for the detection of mutations. Five out of the six beta-globin gene defects were detected, namely, IVS-1 nt5 (G>C), IVS-1 nt1 (G>T), codon 26 (G>A), codon 41-42 (4 bp del) and codon 19 (A>G). The mutation which was not observed in this study was in codon 15 (G>A). The two most common mutations observed were codon 26 (G>A) and IVS-1 nt5 (G>C), which was detected in 26 and 17 patients, respectively. Two patients did not show any of the six mutations. Our results added to the existing data on the common beta-globin gene defects in Kelantan Malay beta-thalassaemia patients.

  3. Fragmentation of daily rhythms associates with obesity and cardiorespiratory fitness in adolescents: The HELENA study.

    PubMed

    Garaulet, Marta; Martinez-Nicolas, Antonio; Ruiz, Jonatan R; Konstabel, Kenn; Labayen, Idoia; González-Gross, Marcela; Marcos, Ascensión; Molnar, Dénes; Widhalm, Kurt; Casajús, Jose Antonio; De Henauw, Stefaan; Kafatos, Anthony; Breidenassel, Christina; Sjöström, Michael; Castillo, Manuel J; Moreno, Luis A; Madrid, Juan A; Ortega, Francisco B

    2016-11-05

    Chronobiology studies periodic changes in living organisms and it has been proposed as a promising approach to investigate obesity. We analyze the association of the characteristics of the rest-activity rhythms with obesity, cardiorespiratory fitness and metabolic risk in adolescents from nine European countries. 1044 adolescents (12.5-17.5 y) were studied. Circadian health was evaluated by actigraphy with accelerometers (Actigraph GT1M). Characteristics of the daytime activity such as fragmentation (intradaily variability), estimated acrophase, and 10 h mean daytime activity index were obtained. Body composition was assessed using Bioelectrical-Impedance-Analysis, skinfold thickness, air-displacement-plethysmography and Dual-energy-X-ray-Absorptiometry. Cardiorespiratory fitness (VO2max) and metabolic risk were studied. Highly fragmented activity rhythms were associated with obesity and central adiposity (P < 0.05). Obese adolescents had ∼3 times higher odds of having a high fragmentation of daytime activity compared to normal weight adolescents OR (95% CI) = 2.8 (1.170, 6.443). A highly fragmented rhythm was also related to lower cardiorespiratory fitness and higher metabolic risk (P < 0.05) so those adolescents classified as low fitness showed a significantly higher fragmentation of daytime activity than those included in the high fitness group (P < 0.0001). Other characteristics of the rhythms such as smaller 10 h daytime mean activity index and delayed estimated acrophase were also related to obesity and metabolic risk (P < 0.05). Our results indicate that the daily organization of the rest-activity cycle is more fragmented in obese and less fit adolescents and correlates with higher metabolic risk. This fact reinforces our hypothesis that disturbances in daily rhythms can be considered as sensitive markers of poorer adolescent's health. Copyright © 2016 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights

  4. [Laser enhanced chemical reaction studies]. [Progress report

    SciTech Connect

    Not Available

    1992-04-01

    Experimental studies of dynamic molecular processes are described with particular emphasis on the use of a powerful infrared diode laser probe technique developed in our laboratory. This technique allows us to determine the final states of CO{sub 2} (and other molecules) produced by collisions, photofragmentation, or chemical reactions with a spectral resolution of 0.0003 cm{sup {minus}1} and a time resolution of 10{sup {minus}7} sec. Such high spectral resolution provides a detailed picture of the vibrational and rotational states of molecules produced by these dynamic events. We have used this experimental method to probe collisions between hot hydrogen/deuterium atoms and CO{sub 2}, between O({sup 1}D) atoms and CO{sub 2}, to study the final states of DC1 molecules produced as a result of the reactions of hot Cl atoms, and to investigate the dynamics of the reaction between OH and CO molecules. Advances in our techniques over the past two years have allowed us to identify and study more than 200 final rotational states in ten different vibrational levels of CO{sub 2} encompassing all 3 normal modes, many overtones, and combination states of the molecule. We have extended the technique to probe a variety of new molecules such as OCS, N{sub 2}O, DCl, and CS{sub 2}. All of this work is aimed at providing experimental tests for polyatomic molecule potential energy surfaces, chemical transition states in complex systems, and theories of reaction dynamic in molecules with more than 3 atoms.

  5. Bulk plasma fragmentation in a C4F8 inductively coupled plasma: A hybrid modeling study

    NASA Astrophysics Data System (ADS)

    Zhao, Shu-Xia; Zhang, Yu-Ru; Gao, Fei; Wang, You-Nian; Bogaerts, Annemie

    2015-06-01

    A hybrid model is used to investigate the fragmentation of C4F8 inductive discharges. Indeed, the resulting reactive species are crucial for the optimization of the Si-based etching process, since they determine the mechanisms of fluorination, polymerization, and sputtering. In this paper, we present the dissociation degree, the density ratio of F vs. CxFy (i.e., fluorocarbon (fc) neutrals), the neutral vs. positive ion density ratio, details on the neutral and ion components, and fractions of various fc neutrals (or ions) in the total fc neutral (or ion) density in a C4F8 inductively coupled plasma source, as well as the effect of pressure and power on these results. To analyze the fragmentation behavior, the electron density and temperature and electron energy probability function (EEPF) are investigated. Moreover, the main electron-impact generation sources for all considered neutrals and ions are determined from the complicated C4F8 reaction set used in the model. The C4F8 plasma fragmentation is explained, taking into account many factors, such as the EEPF characteristics, the dominance of primary and secondary processes, and the thresholds of dissociation and ionization. The simulation results are compared with experiments from literature, and reasonable agreement is obtained. Some discrepancies are observed, which can probably be attributed to the simplified polymer surface kinetics assumed in the model.

  6. Studying barrier-discharge-stimulated plasmachemical reactions

    NASA Astrophysics Data System (ADS)

    Malanichev, V. E.; Malashin, M. V.; Moshkunov, S. I.; Nebogatkin, S. V.; Khomich, V. Yu.; Shmelev, V. M.

    2017-05-01

    Barrier-discharge stimulation of chemical reactions has been studied in the case of methane oxidation by atmospheric oxygen with the formation of carbon monoxide and hydrogen. Experiments in a plasmachemical reactor demonstrated the possibility of increasing the yield of synthesis gas (syngas) by means of plasma pretreatment of the initial mixture of air and methane in a 7: 1 ratio at atmospheric pressure. The output-gas composition was determined by gas chromatography. It is established that the plasma-discharge treatment of the initial gas mixture leads to a 15% increase in the amount of syngas at the reactor output and increases the reaction selectivity with respect to hydrogen and carbon monoxide by 3.2 and 6.5%, respectively.

  7. Soil pretreatment and fast cell lysis for direct polymerase chain reaction from forest soils for terminal restriction fragment length polymorphism analysis of fungal communities.

    PubMed

    Cheng, Fei; Hou, Lin; Woeste, Keith; Shang, Zhengchun; Peng, Xiaobang; Zhao, Peng; Zhang, Shuoxin

    Humic substances in soil DNA samples can influence the assessment of microbial diversity and community composition. Using multiple steps during or after cell lysis adds expenses, is time-consuming, and causes DNA loss. A pretreatment of soil samples and a single step DNA extraction may improve experimental results. In order to optimize a protocol for obtaining high purity DNA from soil microbiota, five prewashing agents were compared in terms of their efficiency and effectiveness in removing soil contaminants. Residual contaminants were precipitated by adding 0.6mL of 0.5M CaCl2. Four cell lysis methods were applied to test their compatibility with the pretreatment (prewashing+Ca(2+) flocculation) and to ultimately identify the optimal cell lysis method for analyzing fungal communities in forest soils. The results showed that pretreatment with TNP+Triton X-100+skim milk (100mM Tris, 100mM Na4P2O7, 1% polyvinylpyrrolidone, 100mM NaCl, 0.05% Triton X-100, 4% skim milk, pH 10.0) removed most soil humic contaminants. When the pretreatment was combined with Ca(2+) flocculation, the purity of all soil DNA samples was further improved. DNA samples obtained by the fast glass bead-beating method (MethodFGB) had the highest purity. The resulting DNA was successfully used, without further purification steps, as a template for polymerase chain reaction targeting fungal internal transcribed spacer regions. The results obtained by terminal restriction fragment length polymorphism analysis indicated that the MethodFGB revealed greater fungal diversity and more distinctive community structure compared with the other methods tested. Our study provides a protocol for fungal cell lysis in soil, which is fast, convenient, and effective for analyzing fungal communities in forest soils.

  8. Direct detection and genotyping of Chlamydia trachomatis in cervical scrapes by using polymerase chain reaction and restriction fragment length polymorphism analysis.

    PubMed Central

    Lan, J; Walboomers, J M; Roosendaal, R; van Doornum, G J; MacLaren, D M; Meijer, C J; van den Brule, A J

    1993-01-01

    Detection and genotyping of Chlamydia trachomatis were optimized by using a polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis performed directly with crude cells of cervical scrapes. Different PCR pretreatment methods were evaluated on samples which were positive for C. trachomatis by cell culture. In comparison with DNA extraction and different proteolytic digestion methods, a simple pretreatment of 10 min of boiling appeared to be optimal for PCR amplification. Crude samples (n = 209) were first screened for C. trachomatis by both cell culture and plasmid PCR. Subsequently, positive samples found by plasmid PCR were subjected to a direct omp1 PCR-based RFLP analysis to differentiate C. trachomatis serovars A to K, Ba, Da, and L1 to L3 and serovariant D-. All cervical scrapes that were found positive for C. trachomatis by cell culture (n = 30) were also positive by plasmid PCR and omp1 PCR and could be easily genotyped. In addition, of the culture-negative group, eight samples were found positive by plasmid PCR. Five of these eight samples were also positive by omp1 PCR; of these five, two were positive by a nested omp1 PCR. Genotyping by RFLP analysis of the 35 omp1 PCR-positive samples showed that serovars D, E, and F are the most prevalent types found in cervical scrapes, while serovariant D- was also detected. This study shows that direct PCR and PCR-based RFLP analysis are feasible for detection and genotyping of C. trachomatis in cervical scrapes and are more sensitive than culture-based serotyping. Images PMID:8099080

  9. Chameleon fragmentation

    SciTech Connect

    Brax, Philippe

    2014-02-01

    A scalar field dark energy candidate could couple to ordinary matter and photons, enabling its detection in laboratory experiments. Here we study the quantum properties of the chameleon field, one such dark energy candidate, in an ''afterglow'' experiment designed to produce, trap, and detect chameleon particles. In particular, we investigate the possible fragmentation of a beam of chameleon particles into multiple particle states due to the highly non-linear interaction terms in the chameleon Lagrangian. Fragmentation could weaken the constraints of an afterglow experiment by reducing the energy of the regenerated photons, but this energy reduction also provides a unique signature which could be detected by a properly-designed experiment. We show that constraints from the CHASE experiment are essentially unaffected by fragmentation for φ{sup 4} and 1/φ potentials, but are weakened for steeper potentials, and we discuss possible future afterglow experiments.

  10. Multi-fragment site-directed mutagenic overlap extension polymerase chain reaction as a competitive alternative to the enzymatic assembly method.

    PubMed

    Wäneskog, Marcus; Bjerling, Pernilla

    2014-01-01

    Methods for introducing multiple site-directed mutations are important experimental tools in molecular biology. Research areas that use these methods include the investigation of various protein modifications in cellular processes, modifying proteins for efficient recombinant expression, and the stabilization of mRNAs to allow for increased protein expression. Introducing multiple site-directed mutations is also an important tool in the field of synthetic biology. There are two main methods used in the assembling of fragments generated by mutagenic primers: enzymatic assembly and overlap extension polymerase chain reaction (OE-PCR). In this article, we present an improved OE-PCR method that can be used for the generation of large DNA fragments (up to 7.4 kb) where at least 13 changes can be introduced using a genomic template. The improved method is faster (due to fewer reaction steps) and more accurate (due to fewer PCR cycles), meaning that it can effectively compete with the enzymatic assembly method. Data presented here show that the site-directed mutations can be introduced anywhere between 50 and 1800 bp from each other. The method is highly reliable and predicted to be applicable to most DNA engineering when the introduction of multiple changes in a DNA sequence is required.

  11. A duplex polymerase chain reaction-restriction fragment length polymorphism for rapid screening of methylenetetrahydrofolate reductase gene variants: Genotyping in acute leukemia.

    PubMed

    Frikha, Rim; Bouayed, Nouha; Ben Rhouma, Bochra; Keskes, Leila; Rebai, Tarek

    2017-04-04

    Methylenetetrahydrofolate reductase (MTHFR; NM_005957.4) is the key enzyme for folate metabolism which plays in DNA biosynthesis and the epigenetic process of DNA methylation. MTHFR gene polymorphisms, the c. 677C>T and c. 1298A>C have been implicated as risk factors for several types of cancers as the acute leukemia. We have optimized a duplex polymerase chain reaction-restriction fragment length polymorphism assay (PCR-RFLP) for the simultaneous detection of both variants in acute leukemia patients, from Tunisia. Genomic DNA was extracted from EDTA-anticoagulant blood samples from a total of 50 patients suffering from acute leukemia (AL). After DNA extraction, the polymerase chain reaction using specific primers, designed using Primer 3 Software. Restriction Fragment Length Polymorphism (RFLP) was performed in two separate tubes followed by agarose gel electrophoresis. This new method has proved to be a rapid, simple, and reliable method that should facilitate high throughput genotyping of MTHFR polymorphisms in acute leukemia. © 2017 Wiley Periodicals, Inc.

  12. Theoretical study of the fragmentation pathways of norbornane in its doubly ionized ground state.

    PubMed

    Knippenberg, Stefan; Hajgató, Balazs; François, Jean-Pierre; Deleuze, Michael S

    2007-10-25

    The potential energy surface of norbornane in its dicationic singlet ground state has been investigated in detail using density functional theory along with the nonlocal hybrid and gradient-corrected Becke three-parameter Lee-Yang-Parr functional (B3LYP) and the cc-pVDZ basis set. For the sake of more quantitative insight into the chemical reactions induced by double ionization of norbornane, this study was supplemented by a calculation of basic thermodynamic state functions coupled to a focal point analysis of energy differences obtained using correlation treatments and basis sets of improving quality, enabling an extrapolation of these energy differences at the CCSD(T) level in the limit of an asymptotically complete (cc-pV infinity Z) basis set. Our results demonstrate the likelihood of an ultrafast intramolecular rearrangement of the saturated hydrocarbon cage after a sudden removal of two electrons into a kinetically metastable five-membered cyclic C5H8+-CH+-CH3 intermediate, prior to a Coulomb explosion into C5H7+=CH2 and CH3+ fragments, which might explain a tremendous rise of electron-impact (e, 2e) ionization cross sections at electron binding energies around the double-ionization threshold. The first step is straightforward and strongly exothermic (DeltaH298 = -114.0 kcal mol-1). The second step is also exothermic (DeltaH298 = -10.2 kcal mol-1) but requires an activation enthalpy (DeltaH298) of 39.7 kcal/mol. The various factors governing the structure of this intermediate, such as electrostatic interactions, inductive effects, cyclic strains, and methylenic hyperconjugation interactions, are discussed in detail.

  13. Fragmentation studies and electrospray ionization mass spectrometry of lapachol: protonated, deprotonated and cationized species.

    PubMed

    Vessecchi, Ricardo; Emery, Flavio S; Galembeck, Sérgio E; Lopes, Norberto P

    2010-07-30

    Electrospray ionization mass spectrometric analysis of lapachol (2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone) was accomplished in order to elucidate the gas-phase dissociation reactions of this important biologically active natural product. The occurrence of protonated and cationized species in the positive mode and of deprotonated species in the negative mode was explored by means of collision-induced dissociation (CID) experiments. For the protonated molecule, the H(2)O and C(4)H(8) losses occur by two competitive channels. For the deprotonated molecule, the even-electron rule is not conserved, and the radicalar species are eliminated by formation of distonic anions. The fragmentation mechanism for each ion was suggested on the basis of computational thermochemistry. Atomic charges, relative energies, and frontier orbitals were employed aiming at a better understanding of the gas-phase reactivity of lapachol. Potential energy surfaces for fragmentation reactions were obtained by the B3LYP/6-31+G(d,p) model.

  14. DNA Flexibility Studied by Covalent Closure of Short Fragments into Circles

    NASA Astrophysics Data System (ADS)

    Shore, David; Langowski, Jorg; Baldwin, Robert L.

    1981-08-01

    The ring closure probability, or j factor, has been measured for DNA restriction fragments of defined sequence bearing EcoRI cohesive ends and ranging in size from 126 to 4361 base pairs (bp). The j factor is defined as the ratio of the equilibrium constants for cyclization and for bimolecular association via the cohesive ends. The end-joining reactions are fast compared to covalent closure of the cohesive ends by T4 DNA ligase. The rate of ligase closure is shown to be proportional to the equilibrium fraction of DNA molecules with joined cohesive ends, both in cyclization and in bimolecular association reactions. The j factor changes by less than 10-fold between 242 and 4361 bp, whereas it decreases by more than 100-fold between 242 and 126 bp as the DNA reaches the size range of the persistence length (150 bp). As regards ring closure, short DNA fragments are surprisingly flexible. These data are in good agreement with predictions by others for the ring closure probability of a wormlike chain.

  15. Comments on "a study of the collisional fragmentation problem using the gamma distribution approximation".

    PubMed

    Nadarajah, Saralees

    2007-04-15

    M. Kostoglou and A.J. Karabelas [J. Colloid Interface Sci. 303 (2006) 419-429] proposed using a gamma distribution approximation to study a collisional fragmentation problem. This approximation involved two types of integrals and the use of continued fraction expansions for their computation. In this Comment, explicit expressions are derived for computing the integrals.

  16. COSMO-DFTr study of cellulosic fragments: structural features, relative energy, and hydration energies

    USDA-ARS?s Scientific Manuscript database

    The study of cellulosic fragments by DFTr is a continuation of our efforts to produce quality structural data that will be valuable to those working in the field of cellulose structure and enzymatic degradation. Using a reduced basis set and density functional DFTr(B3LYP), the time and computer dem...

  17. Studies Toward the Synthesis of Spirolides: Assembly of the Elaborated E-Ring Fragment

    PubMed Central

    Stivala, Craig E.; Zakarian, Armen

    2009-01-01

    A stereoselective synthesis of the spiroimine fragment of spirolide C is described. The congested C7 and C29 tertiary and quaternary centers are constructed by a diastereoselective Ireland-Claisen rearrangement. The E ring is completed by means of an aldol cyclocondensation. Additional studies were preformed on the advanced intermediate to probe a future coupling strategy. PMID:19199776

  18. Experimental study on the friction effect of plastic stents for biliary stone fragmentation (with video).

    PubMed

    Kwon, Chang-Il; Kim, Gwangil; Jeong, Seok; Choi, Sung Hoon; Ko, Kwang Hyun; Lee, Don Haeng; Cho, Joo Young; Hong, Sung Pyo

    2017-06-16

    In patients with irretrievable or intractable bile duct stone, temporary insertion of a plastic stent (PS) followed by further endoscopic retrograde cholangiopancreatography (ERCP) or surgery has been recommended as a 'bridge' therapy. However, the exact mechanism of stone fragmentation has not been discovered. The aim of the present study was to evaluate whether PS shape can facilitate stone fragmentation. Using a new in vitro bile flow phantom model, we compared the friction effect among three different PS groups (straight PS group, double pigtail-shaped PS group, and screw-shaped PS group) and a control group. Each group had 10 silicon tube blocks that separately contained one stone and two PS. The control group had 10 blocks each with only a stone and no PS. We carried out analysis of the friction effect by stone weight and volume changes among the groups, excluding fragmented stones. After 8 weeks, complete fragmentation was noted in one out of 34 cholesterol stones (2.9%) and in four out of six pigmented stones (66.7%). Fragmentation tended to be more prominent in the screw-shaped PS group than in the straight PS group, double pigtail-shaped group, and control group (volume change: -11.33%, 7.94%, 4.43%, and 2.05%, respectively, P = 0.1390; weight change: -9.30%, 0.71%, -0.10%, and -1.23%, respectively, P = 0.3553). Stone fragmentation may be induced by PS friction effect. Also, screw-shaped plastic stents may improve friction effect. These results may help guide future PS development and clinical decisions. © 2017 Japan Gastroenterological Endoscopy Society.

  19. Competition between functionalization and fragmentation pathways in the OH-initiated oxidation of aqueous tartaric acid droplets: Reaction products and model simulations

    NASA Astrophysics Data System (ADS)

    Cheng, C. T.; Chow, C. Y.; Chan, M. N.; Zuend, A.; Berkemeier, T.; Shiraiwa, M.

    2015-12-01

    To gain better insights into the competition between functionalization and fragmentation pathways for oxygenated organic compounds, we investigate the OH-radical initiated oxidation of aqueous tartaric acid (C4H6O6) droplets using an aerosol flow tube reactor. The molecular composition of reaction products is characterized by an atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high resolution mass spectrometer. The reaction produces four major products: a functionalization product (C4H4O6) and three fragmentation products (C3H4O4, C3H2O4 and C3H2O5), with a predominance of the functionalization product which supports the literature result that only less than 10% of carbon loss was observed for the OH oxidation of tartaric acid. The formation of the functionalization product (2-hydroxy-3-oxosuccinic acid, C4H4O6) can be attributed to that the tertiary alkyl radical, formed after hydrogen abstraction, reacts with an O2 molecule to form a hydroxyperoxyl radical which tends to quickly undergo intramolecular HO2 elimination without fragmentation. The molecular transformation of aqueous tartaric acid droplets is stimulated using the kinetic multi-layer model of gas-particle interactions in aerosols and clouds (KM-GAP) and the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model in order to take into account the change in particle-phase water and activities of reaction products during the oxidation. Results suggest that aqueous tartaric acid droplets become slightly less hygroscopic after oxidation due to the formation of less polar products. The formation of products with different hygroscopicities and volatilities largely determine the amount of particle-phase water, which in turn governs the size of the aqueous droplets and the concentration of the reactants. Consideration of the variation in water content in response to the chemical evolution in the aerosol is needed to better understand

  20. Computational Hydrocode Study of Target Damage due to Fragment-Blast Impact

    SciTech Connect

    Hatch-Aguilar, T; Najjar, F; Szymanski, E

    2011-03-24

    ), Pressure-Impulse (PI) and Time of Duration (TD). Other peculiarities include the radial decrease in pressure from the source, any fireball size measurement, and subsequent increase in temperature from the passing of the shockwave through the surrounding medium. In light of all of these metrics, the loading any object receives from a blast event becomes intricately connected to the distance between itself and the source. Because of this, a clear distinction is made between close-in effects and those from a source far away from the object of interest. Explosively generated fragments on the other hand are characterized by means of their localized damage potential. Metrics such as whether the fragment penetrates or perforates a given object is quantified as well as other variables including fragment's residual velocity, % kinetic energy decrease, residual fragment mass and other exit criteria. A fragment launched under such violent conditions could easily be traveling at speeds in excess of 2500 ft/s. Given these speeds it is conceivable to imagine how any given fragment could deliver a concentrated load to a target and penetrates through walls, vehicles or even the protection systems of nearby personnel. This study will focus on the individual fragment-target impact event with the hopes of expanding it to eventually include statistical procedures. Since this is a modeling excursion into the combined frag-blast target damage effects the numerical methods used to frame this problem become important in-so-far as the simulations are done in a consistent manner. For this study a Finite-Element based Hydrocode solution called ALE3D (ALE=Arbitrary Lagrangian-Eulerian) was utilized. ALE3D is developed by Lawrence Livermore National Laboratory (Livermore, CA), and as this paper will show, successfully implemented a converged ALE formulation including as many of the different aspects needed to query the synergistic damage on a given target. Further information on the modeling setup is

  1. Study of aneuploidy rate and sperm DNA fragmentation in large-headed, multiple-tailed spermatozoa.

    PubMed

    Brahem, S; Mehdi, M; Elghezal, H; Saad, A

    2012-04-01

    The aim of this study was to analyse the meiotic segregation and DNA fragmentation rates in ejaculated spermatozoa of Tunisian men who presented the macrocephalic sperm head syndrome and to compare the results with those from 20 fertile men with normal semen profiles. Sperm DNA fragmentation was evaluated by the terminal desoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick-end labelling assay. Fluorescence in situ hybridisation for chromosomes X, Y and 18 was performed for the study of meiotic segregation. Despite a normal blood karyotype, patients with large-headed spermatozoa showed a significantly higher incidence of sperm chromosomal abnormalities compared with the control group. For all the patients, tetraploidy, triploidy and diploidy were the most observed abnormalities. A very high level of DNA fragmentation was shown for these patients. In conclusion, our results demonstrated that patients with large-headed, multiple-tailed spermatozoa had significantly higher incidence of sperm chromosomal abnormalities and very high level of DNA fragmentation. So intracytoplasmic sperm injection should not be recommended to these patients, not only because of its low chances of success rate but also because of its high genetic risk. © 2011 Blackwell Verlag GmbH.

  2. Differentiation of canine distemper virus isolates in fur animals from various vaccine strains by reverse transcription-polymerase chain reaction-restriction fragment length polymorphism according to phylogenetic relations in china.

    PubMed

    Wang, Fengxue; Yan, Xijun; Chai, Xiuli; Zhang, Hailing; Zhao, Jianjun; Wen, Yongjun; Wu, Wei

    2011-02-27

    In order to effectively identify the vaccine and field strains of Canine distemper virus (CDV), a new differential diagnostic test has been developed based on reverse transcription-polymerase chain reaction (RT-PCR) and restriction fragment length polymorphism (RFLP). We selected an 829 bp fragment of the nucleoprotein (N) gene of CDV. By RFLP analysis using BamHI, field isolates were distinguishable from the vaccine strains. Two fragments were obtained from the vaccine strains by RT-PCR-RFLP analysis while three were observed in the field strains. An 829 nucleotide region of the CDV N gene was analyzed in 19 CDV field strains isolated from minks, raccoon dogs and foxes in China between 2005 and 2007. The results suggest this method is precise, accurate and efficient. It was also determined that three different genotypes exist in CDV field strains in fur animal herds of the north of China, most of which belong to Asian type. Mutated field strains, JSY06-R1, JSY06-R2 and JDH07-F1 also exist in Northern China, but are most closely related to the standard virulent strain A75/17, designated in Arctic and America-2 genetype in the present study, respectively.

  3. Production of cold target-like fragments in the reaction of /sup 48/Ca+/sup 248/Cm

    SciTech Connect

    Gaeggeler, H.; Bruechle, W.; Bruegger, M.; Schaedel, M.; Suemmerer, K.; Wirth, G.; Kratz, J.V.; Lerch, M.; Blaich, T.; Herrmann, G.

    1986-06-01

    Yields for isotopes of Rn through Pu have been measured in the reaction /sup 48/Ca+/sup 248/Cm at an energy of 248--263 MeV (1.04--1.10 times the Coulomb barrier). Despite the low bombarding energy, high and essentially constant integral yields of about 1 to 2 mb for the elements Rn through U were observed. There is evidence that these nuclides are produced with little excitation energy.

  4. The study of spermatic DNA fragmentation and sperm motility in infertile subjects.

    PubMed

    Peluso, Giuseppina; Palmieri, Alessandro; Cozza, Pietro Paolo; Morrone, Giancarlo; Verze, Paolo; Longo, Nicola; Mirone, Vincenzo

    2013-04-19

    Although the pathophysiology of the testicular damage associated with varicocele remains unclear, sperm DNA damage has been identified as a potential explanation for this cause of male infertility. The current study was designed to determine the extent of sperm nuclear DNA damage in patients with varicocele, and to examine its relationship with parameters of seminal motility. Semen samples from 60 patients with clinical varicocele and 90 infertile men without varicocele were examined. Varicocele sperm samples were classified as normal or pathological according to the 1999 World Health Organizzation guidelines. Sperm DNA damage was evalutated using the Halosperm kit, an improved Sperm Chromatin Dispersion (SCD) test. The DNA fragmentation index (DFI: percentage of sperm with denatured nuclei) values was significantly higher in patients with varicocele, either with normal or abnormal (DFI 25.8 ± 3.2 vs 17.4 ± 2.8 - P < 0,01) semen profiles. In addition, an inverse correlation was found between spermatic motility and the degree of spermatic DNA fragmentation in patients with clinical varicocele. Varicocele is associated with high levels of DNA-damage in spermatozoa. In addition, in subjects with varicocele, abnormal spermatozoa motility is associated with higher levels of sperm DNA fragmentation. DNA fragmentation may therefore be an essential additional diagnostic test that should be recommended for patients with clinical varicocele.

  5. Yrast isomers in exotic [ital N]=81 nucleus [sup 151]Yb studied using a fragment mass analyzer

    SciTech Connect

    Nisius, D.; Fornal, B.; Bearden, I.G.; Broda, R.; Mayer, R.H.; Grabowski, Z.W.; Daly, P.J. ); Davids, C.N.; Ahmad, I.; Back, B.B.; Bindra, K.; Carpenter, M.P.; Chung, W.; Henderson, D.; Henry, R.G.; Janssens, R.V.F.; Khoo, T.L.; Lauritsen, T.; Liang, Y.; Soramel, F. ); Ramayya, A.V. )

    1993-05-01

    Product recoils from the reaction [sup 96]Ru +255 MeV [sup 58]Ni [r arrow] [sup 154]Hf[sup *] were analyzed using the Argonne Fragment Mass Analyzer and transported to a collector foil behind the focal plane, where decay of [mu]s isomers could be studied under low background conditions. The recoils were dispersed in [ital A]/[ital q] as they traversed the position-sensitive focal-plane detector, and recoil--[gamma]-ray coincidences could thus be used to assign masses for specific [gamma]-ray cascades. By use of these methods, yrast isomers with half-lives of 2.6(7) [mu]s and 20(1) [mu]s have been firmly assigned to the exotic [ital N]=81 nucleus [sup 151]Yb, and the main features of the isomeric decays have been established. The yrast level structure of [sup 151]Yb and lighter [ital N]=81 isotones are compared.

  6. Experimental studies of gas-aerosol reactions

    NASA Astrophysics Data System (ADS)

    Gupta, Anand

    1991-05-01

    The aqueous phase oxidation of SO2 by H2O2 is believed to the principle mechanism for atmospheric sulfate formation in cloud droplets. However, no studies in noncloud aerosol systems have been reported. The objective is to quantify the importance of the noncloud liquid phase reactions of SO2 by H2O2 in the atmosphere. Growth rates of submicron droplets exposed to SO2 and H2O2 were measured using the tandem differential mobility analyzer (TDMA) technique (Rader and McMurry, 1986). The technique uses differential mobility analyzers (DMA's) to generate monodisperse particles and to measure particle size after the reaction. To facilitate submicron monodisperse droplet production with the DMA, a low-ion-concentration charter capable of generating singly charged particles up to 1.0 microns was developed and experimentally evaluated. The experiments were performed using dry and deliquesced (NH4)2SO4 particles with SO2 and H2O2 concentrations from 0-860 ppb and 0-150 ppb, respectively. No growth was observed for dry particles. For droplets greater than or equal to 0.3 microns, the fractional diameter growth was independent of particle size and for droplets less than or equal to 0.2 microns, it decreased as particle size decreased. The observed decrease is due to NH3 evaporation. As ammonia evaporates, droplet pH decreases causing the oxidation rate to decrease, leading to a lower growth rate. To predict the size-dependent growth rates, a theoretical model was developed using solution thermodynamics, gas/particle equilibrium, and chemical kinetics. The experimental and theoretical results are in reasonable agreement. For dry (NH4)2SO4 particles exposed to SO2, H2O2, NH3, and H2O vapor, surface reaction-controlled growth was observed. Particle growth was very sensitive to particle composition. No growth was observed for Polystyrene latex particles, whereas (NH4)2SO4 particles doped with catalysts (Fe(2+), Fe(3+), Mn(2+) and Cu(2+)) in a molar ratio of 1:500 grew slower than

  7. Experimental Studies of Gas-Aerosol Reactions

    NASA Astrophysics Data System (ADS)

    Gupta, Anand

    1991-02-01

    The aqueous phase oxidation of SO_2 by H_2O_2 is believed to be the principle mechanism for atmospheric sulfate formation in cloud droplets. However, no studies in noncloud aerosol systems have been reported. The objective of this thesis is to quantify the importance of the noncloud liquid phase reactions of SO_2 by H_2O_2 in the atmosphere. In this thesis growth rates of submicron droplets exposed to SO_2 and H_2 O_2 were measured using the tandem differential mobility analyzer (TDMA) technique (Rader and McMurry, 1986). The technique uses differential mobility analyzers (DMAs) to generate monodisperse particles and to measure particle size after the reaction. To facilitate submicron monodisperse droplet production with the DMA, a low-ion-concentration charger capable of generating singly charged particles up to 1.0 μm was developed and experimentally evaluated. The experiments were performed using dry and deliquesced (NH_4)_2SO _4 particles with SO_2 and H_2O_2 concentrations from 0-860 ppb and 0-150 ppb, respectively. No growth was observed for dry particles. For droplets >=0.3 mum, the fractional diameter growth was independent of particle size and for droplets <=0.2 mum, it decreased as particle size decreased. The observed decrease is due to NH_3 evaporation. As ammonia evaporates, droplet pH decreases causing the oxidation rate to decrease, leading to a lower growth rate. To predict the size-dependent growth rates, a theoretical model was developed using solution thermodynamics, gas/particle equilibrium and chemical kinetics. The experimental and theoretical results are in reasonable agreement. For dry (NH_4) _2SO_4 particles exposed to SO_2, H_2O _2, NH_3 and H_2O vapor, surface reaction-controlled growth was observed. Particle growth was very sensitive to particle composition. No growth was observed for Polystyrene latex particles, whereas (NH_4) _2SO_4 particles doped with catalysts (Fe^{2+} , Fe^{3+}, Mn ^{2+}, Cu^{2+ }) in a molar ratio of 1:500 grew

  8. Double Gene Targeting Multiplex Polymerase Chain Reaction-Restriction Fragment Length Polymorphism Assay Discriminates Beef, Buffalo, and Pork Substitution in Frankfurter Products.

    PubMed

    Hossain, M A Motalib; Ali, Md Eaqub; Abd Hamid, Sharifah Bee; Asing; Mustafa, Shuhaimi; Mohd Desa, Mohd Nasir; Zaidul, I S M

    2016-08-17

    Beef, buffalo, and pork adulteration in the food chain is an emerging and sensitive issue. Current molecular techniques to authenticate these species depend on polymerase chain reaction (PCR) assays involving long and single targets which break down under natural decomposition and/or processing treatments. This novel multiplex polymerase chain reaction-restriction fragment length polymorphism assay targeted two different gene sites for each of the bovine, buffalo, and porcine materials. This authentication ensured better security, first through a complementation approach because it is highly unlikely that both sites will be missing under compromised states, and second through molecular fingerprints. Mitochondrial cytochrome b and ND5 genes were targeted, and all targets (73, 90, 106, 120, 138, and 146 bp) were stable under extreme boiling and autoclaving treatments. Target specificity and authenticity were ensured through cross-amplification reaction and restriction digestion of PCR products with AluI, EciI, FatI, and CviKI-1 enzymes. A survey of Malaysian frankfurter products revealed rampant substitution of beef with buffalo but purity in porcine materials.

  9. Effects of fragmentation parameter variations on estimates of galactic cosmic ray exposure: Dose sensitivity studies for aluminum shields

    NASA Technical Reports Server (NTRS)

    Townsend, Lawrence W.; Cucinotta, Francis A.; Shinn, Judy L.; Wilson, John W.

    1992-01-01

    Initial studies of the sensitivities of estimates of particle fluence, absorbed dose, and dose equivalent to fragmentation parameter variations are undertaken by using the LaRC galactic cosmic ray transport code (HZETRN). The new results, presented as a function of aluminum shield thickness, include upper and lower bounds on dose/dose equivalent corresponding to the physically realistic extremes of the fragmentation process and the percentage of variation of the dose/dose equivalent as a function of fragmentation parameter variation.

  10. Dynamical simulation of the fission process and anisotropy of the fission fragment angular distributions of excited nuclei produced in fusion reactions

    NASA Astrophysics Data System (ADS)

    Eslamizadeh, H.

    2016-10-01

    Abstract. A stochastic approach based on four-dimensional Langevin equations was applied to calculate the anisotropy of fission fragment angular distributions, average prescission neutron multiplicity, and the fission probability in a wide range of fissile parameters for the compound nuclei 197Tl,225Pa,248Cf , and 264Rf produced in fusion reactions. Three collective shape coordinates plus the projection of total spin of the compound nucleus to the symmetry axis K were considered in the four-dimensional dynamical model. In the dynamical calculations, nuclear dissipation was generated through the chaos-weighted wall and window friction formula. Furthermore, in the dynamical calculations the dissipation coefficient of K ,γk was considered as a free parameter, and its magnitude inferred by fitting measured data on the anisotropy of fission fragment angular distributions for the compound nuclei 197Tl,225Pa,248Cf , and 264Rf. Comparison of the calculated results for the anisotropy of fission fragment angular distributions with the experimental data showed that the results of the calculations are in good agreement with the experimental data by using values of the dissipation coefficient of K equal to (0.185-0.205), (0.175-0.192), (0.077-0.090), and (0.075-0.085) (MeVzs ) -1 /2 for the compound nuclei 197Tl,225Pa,248Cf , and 264Rf, respectively. It was also shown that the influence of the dissipation coefficient of K on the results of the calculations of the prescission neutron multiplicity and fission probability is small.

  11. Chemical redox reactions in ES-MS: Study of electrode reactions

    SciTech Connect

    Zhou, Feimeng; VAn Berkel, G.J.

    1995-12-31

    The authors previously demonstrated that chemical redox reactions can be used to ionize neutral commpounds for electrospray mass spectrometric (ES-MS) detection. Two different compounds, viz, C{sub 60}F{sub 48} and {beta}-carotene were used to demonstrate the utility of chemical redox reactions with on-line ES-MS for the elucidation of mechanisms of complicated electron transfer reactions and for the kinetic study of electrode reactions in which relatively short-lived intermediates are involved.

  12. T Oligo-Primed Polymerase Chain Reaction (TOP-PCR): A Robust Method for the Amplification of Minute DNA Fragments in Body Fluids.

    PubMed

    Nai, Yu-Shin; Chen, Tzu-Han; Huang, Yu-Feng; Midha, Mohit K; Shiau, Hsin-Chieh; Shen, Chen-Yang; Chen, Chien-Jen; Yu, Alice L; Chiu, Kuo Ping

    2017-01-17

    Body fluid DNA sequencing is a powerful noninvasive approach for the diagnosis of genetic defects, infectious agents and diseases. The success relies on the quantity and quality of the DNA samples. However, numerous clinical samples are either at low quantity or of poor quality due to various reasons. To overcome these problems, we have developed T oligo-primed polymerase chain reaction (TOP-PCR) for full-length nonselective amplification of minute quantity of DNA fragments. TOP-PCR adopts homogeneous "half adaptor" (HA), generated by annealing P oligo (carrying a phosphate group at the 5' end) and T oligo (carrying a T-tail at the 3' end), for efficient ligation to target DNA and subsequent PCR amplification primed by the T oligo alone. Using DNA samples from body fluids, we demonstrate that TOP-PCR recovers minute DNA fragments and maintains the DNA size profile, while enhancing the major molecular populations. Our results also showed that TOP-PCR is a superior method for detecting apoptosis and outperforms the method adopted by Illumina for DNA amplification.

  13. Excitation energy dependence of fragment-mass distributions from fission of 180,190Hg formed in fusion reactions of 36Ar + 144,154Sm

    DOE PAGES

    Nishio, K.; Andreyev, A. N.; Chapman, R.; ...

    2015-06-30

    Mass distributions of fission fragments from the compound nuclei 180Hg and 190 Hg formed in fusion reactions 36Ar + 144 Smand 36Ar + 154Sm, respectively, were measured at initial excitation energies of E*(180Hg) = 33-66 MeV and E*(190Hg) = 48-71 MeV. In the fission of 180Hg, the mass spectra were well reproduced by assuming only an asymmetric-mass division, with most probable light and heavy fragment masses more » $$\\overline{A}_L$$/$$\\overline{A}_H$$ = 79/101. The mass asymmetry for 180Hg agrees well with that obtained in the low-energy β+/EC-delayed fission of 180Tl, from our earlier ISOLDE(CERN) experiment. Fission of 190Hg is found to proceed in a similar way, delivering the mass asymmetry of$$\\overline{A}_L$$/$$\\overline{A}_H$$ = 83/107, throughout the measured excitation energy range. The persistence as a function of excitation energy of the mass-asymmetric fission for both proton-rich Hg isotopes gives strong evidence for the survival of microscopic effects up to effective excitation energies of compound nuclei as high as 40 MeV. In conclusion, this behavior is different from fission of actinide nuclei and heavier mercury isotope 198Hg.« less

  14. T Oligo-Primed Polymerase Chain Reaction (TOP-PCR): A Robust Method for the Amplification of Minute DNA Fragments in Body Fluids

    PubMed Central

    Nai, Yu-Shin; Chen, Tzu-Han; Huang, Yu-Feng; Midha, Mohit K.; Shiau, Hsin-Chieh; Shen, Chen-Yang; Chen, Chien-Jen; Yu, Alice L.; Chiu, Kuo Ping

    2017-01-01

    Body fluid DNA sequencing is a powerful noninvasive approach for the diagnosis of genetic defects, infectious agents and diseases. The success relies on the quantity and quality of the DNA samples. However, numerous clinical samples are either at low quantity or of poor quality due to various reasons. To overcome these problems, we have developed T oligo-primed polymerase chain reaction (TOP-PCR) for full-length nonselective amplification of minute quantity of DNA fragments. TOP-PCR adopts homogeneous “half adaptor” (HA), generated by annealing P oligo (carrying a phosphate group at the 5′ end) and T oligo (carrying a T-tail at the 3′ end), for efficient ligation to target DNA and subsequent PCR amplification primed by the T oligo alone. Using DNA samples from body fluids, we demonstrate that TOP-PCR recovers minute DNA fragments and maintains the DNA size profile, while enhancing the major molecular populations. Our results also showed that TOP-PCR is a superior method for detecting apoptosis and outperforms the method adopted by Illumina for DNA amplification. PMID:28094343

  15. Excitation energy dependence of fragment-mass distributions from fission of 180,190Hg formed in fusion reactions of 36Ar + 144,154Sm

    NASA Astrophysics Data System (ADS)

    Nishio, K.; Andreyev, A. N.; Chapman, R.; Derkx, X.; Düllmann, Ch. E.; Ghys, L.; Heßberger, F. P.; Hirose, K.; Ikezoe, H.; Khuyagbaatar, J.; Kindler, B.; Lommel, B.; Makii, H.; Nishinaka, I.; Ohtsuki, T.; Pain, S. D.; Sagaidak, R.; Tsekhanovich, I.; Venhart, M.; Wakabayashi, Y.; Yan, S.

    2015-09-01

    Mass distributions of fission fragments from the compound nuclei 180Hg and 190Hg formed in fusion reactions 36Ar + 144Sm and 36Ar + 154Sm, respectively, were measured at initial excitation energies of E* (180Hg) = 33- 66 MeV and E* (190Hg) = 48- 71 MeV. In the fission of 180Hg, the mass spectra were well reproduced by assuming only an asymmetric-mass division, with most probable light and heavy fragment masses AbarL /AbarH = 79 / 101. The mass asymmetry for 180Hg agrees well with that obtained in the low-energy β+ / EC -delayed fission of 180Tl, from our earlier ISOLDE(CERN) experiment. Fission of 190Hg is found to proceed in a similar way, delivering the mass asymmetry of AbarL /AbarH = 83 / 107, throughout the measured excitation energy range. The persistence as a function of excitation energy of the mass-asymmetric fission for both proton-rich Hg isotopes gives strong evidence for the survival of microscopic effects up to effective excitation energies of compound nuclei as high as 40 MeV. This behavior is different from fission of actinide nuclei and heavier mercury isotope 198Hg.

  16. Molecular characterization of Streptococcus suis strains by 16S–23S intergenic spacer polymerase chain reaction and restriction fragment length polymorphism analysis

    PubMed Central

    Le Devendec, Laëtitia; Gottschalk, Marcelo; Kobisch, Marylène

    2006-01-01

    Abstract We developed a new molecular method of typing Streptococcus suis based on polymerase chain reaction (PCR) amplification of a large fragment of rRNA genes, including a part of the 16S and 23S genes and the 16S–23S intergenic spacer region (ISR), followed by restriction fragment length polymorphism (RFLP) analysis with RsaI or MboII endonuclease. The 16S–23S ISRs of 5 S. suis isolates were sequenced and compared. Size and sequence polymorphisms were observed between the S735 reference strain and the 4 wild-type strains. The genetic relationships between 138 independent S. suis strains belonging to various serotypes, isolated from swine or human cases, were determined. The discriminatory power of the method was > 0.95, the threshold value for interpreting typing results with confidence (0.954 with RsaI and 0.984 with RsaI plus MboII). The in vitro reproducibility was 100%. The strains isolated from humans were less genetically diverse than the strains isolated from pigs. For the first time, 2 molecular patterns (R6, M9) were significantly associated with S. suis serotype 2 strains. This genetic tool could be valuable in distinguishing individual isolates of S. suis during epidemiologic investigations. PMID:16639941

  17. Asymmetry effects in fragment production

    NASA Astrophysics Data System (ADS)

    Kaur, Manpreet; Kaur, Varinderjit

    2016-05-01

    The production of different fragments has been studied by taking into account the mass asymmetry of the reaction and employing the momentum dependent interactions. Two different set of asymmetric reactions have been analyzed while keeping Atotal fixed using soft momentum dependent equation of state. Our results indicate that the impact of momentum dependent interactions is different in lighter projectile systems as compared to heavier ones. The comparative analysis of IQMD simulations with the experimental data in case of heavier projectile and lighter target system for the reaction of 197Au+27Al (η = 0.7) at E = 600 MeV/nucleon shows that with the inclusion of MDI we are able, upto some extent, to reproduce the experimental universality of rise and fall of intermediate mass fragments (IMFs).

  18. Asymmetry effects in fragment production

    SciTech Connect

    Kaur, Manpreet; Kaur, Varinderjit

    2016-05-06

    The production of different fragments has been studied by taking into account the mass asymmetry of the reaction and employing the momentum dependent interactions. Two different set of asymmetric reactions have been analyzed while keeping At{sub otal} fixed using soft momentum dependent equation of state. Our results indicate that the impact of momentum dependent interactions is different in lighter projectile systems as compared to heavier ones. The comparative analysis of IQMD simulations with the experimental data in case of heavier projectile and lighter target system for the reaction of {sup 197}Au+{sup 27}Al (η = 0.7) at E = 600 MeV/nucleon shows that with the inclusion of MDI we are able, upto some extent, to reproduce the experimental universality of rise and fall of intermediate mass fragments (IMFs).

  19. The N-terminal fragment of the tomato torrado virus RNA1-encoded polyprotein induces a hypersensitive response (HR)-like reaction in Nicotiana benthamiana.

    PubMed

    Wieczorek, Przemysław; Obrępalska-Stęplowska, Aleksandra

    2016-07-01

    The hypersensitive response (HR) is a defence reaction observed during incompatible plant-pathogen interactions in plants infected with a wide range of fungi, bacteria and viruses. Here, we show that an N-terminal polyprotein fragment encoded by tomato torrado virus RNA1, located between the first ATG codon and the protease cofactor (ProCo) motif, induces an HR-like reaction in Nicotiana benthamiana. Agrobacterium tumefaciens-mediated transient expression of the first 105 amino acids (the calculated molecular weight of the fragment was ca. 11.33 kDa, hereafter refered to as the 11K domain) from ToTV RNA1 induced an HR-like phenotype in infiltrated leaves. To investigate whether the 11K domain could influence the virulence and pathogenicity of a recombinant virus, we created a potato virus X (PVX) with the 11K coding sequence inserted under a duplicated coat protein promoter. We found that 11K substantially increased the virulence of the recombinant virus. Disease phenotype induced in N. benthamiana by PVX-11K was characterized by strong local and systemic necrosis. This was not observed when the 11K domain was expressed from PVX in an antisense orientation. Further analyses revealed that the 11K domain could not suppress posttranscriptional gene silencing (PTGS) of green fluorescent protein (GFP) in the N. benthamiana 16c line. In silico analysis of the predicted secondary structure of the 11K domain indicated the presence of two putative helices that are highly conserved in tomato-infecting representatives of the genus Torradovirus.

  20. Solid-state and unilateral NMR study of deterioration of a Dead Sea Scroll fragment.

    PubMed

    Masic, A; Chierotti, M R; Gobetto, R; Martra, G; Rabin, I; Coluccia, S

    2012-02-01

    Unilateral and solid-state nuclear magnetic resonance (NMR) analyses were performed on a parchment fragment of the Dead Sea Scroll (DSS). The analyzed sample belongs to the collection of non-inscribed and nontreated fragments of known archaeological provenance from the John Rylands University Library in Manchester. Therefore, it can be considered as original DSS material free from any contamination related to the post-discovery period. Considering the paramount significance of the DSS, noninvasive approaches and portable in situ nondestructive methods are of fundamental importance for the determination of composition, structure, and chemical-physical properties of the materials under study. NMR studies reveal low amounts of water content associated with very short proton relaxation times, T(1), indicating a high level of deterioration of collagen molecules within scroll fragments. In addition, (13)C cross-polarization magic-angle-spinning (CPMAS) NMR spectroscopy shows characteristic peaks of lipids whose presence we attribute to the production technology that did not involve liming. Extraction with chloroform led to the reduction of both lipid and protein signals in the (13)C CPMAS spectrum indicating probable involvement of lipids in parchment degradation processes. NMR absorption and relaxation measurements provide nondestructive, discriminative, and sensitive tools for studying the deterioration effects on the organization and properties of water and collagen within ancient manuscripts.

  1. Electrospray ionization mass spectrometric studies on the characteristic fragmentation of Asp/cyclen conjugates.

    PubMed

    Ma, Chunying; Li, Chao; Luan, Xingrong; Zhang, Jin; Qiao, Renzhong; Zhao, Yufen

    2014-03-30

    Differentiation and structural characterization of Asp/cyclen conjugates by electrospray ionization tandem mass spectrometry (ESI-MS(n)) are significantly important for their biomedical application. Hence, the present study is conducted. The fragmentations of Asp/cyclen conjugates generated by positive ion mode electrospray ionization were examined here by low-energy collision-induced dissociation (CID). ESI-MS(n) spectra of cyclen were acquired to confirm cyclen contraction products derived from the studied compounds. The fragments derived from the Asp/cyclen conjugates were proved by deuterium-exchange experiments. Asp/cyclen conjugates displayed characteristic dissociation pathways, including cleavages of amide bonds, loss of NH3 and cyclen contraction pathways. It was observed that cleavages of C-terminal amide bonds generated b2 and b2  + H2O ions from the protonated CyclenAspAspAsp and a b1  + H2O ion from the protonated CyclenAspAsp. In addition, various cyclen contraction products were also observed. In ESI-MS(n) spectra of studied compounds, fragments of bn-1  + H2O or cyclic anhydride were generated due to facile mobilization of C-terminal or side-chain COOH protons. In addition, the cyclen contraction products were detected. These results might provide sufficient information for the identification of Asp/cyclen conjugates by mass spectrometry. Copyright © 2014 John Wiley & Sons, Ltd.

  2. Effect of metal fragments in brain on electrical monitoring: In vitro and in vivo rat studies

    NASA Astrophysics Data System (ADS)

    Ahmed, A.; Bodo, M.; Armonda, R. A.

    2010-04-01

    Preliminary results showed, measurements by rheoencephalography (REG) very promising as a practical, noninvasive continuous monitoring modality of traumatic brain/blast injuries. As the impact of metal fragments on the REG signal is unknown, we report here results of our study .The in vitro study confirmed that impedance pulse amplitude waves do not change in the presence of metal (needles) placed between electrodes. In vivo studies: rats under anesthesia (10 rats, 101 trials) were measured after implantation of EEG and REG electrodes in the brain. Metal fragments were represented by 18 g needles inserted and removed between EEG and REG electrodes. Data were stored in a PC. EEG recording typically showed amplitude decrease; REG showed transitory amplitude increase after placement of a needle into either hemisphere. Removal of needles caused a decrease in REG amplitude after a transitory increase. The change in REG amplitude statistically was non-significant. Cerebral blood flow (CBF) autoregulation(AR) persisted following placement of metal fragments in rat brain.

  3. A study of the fragmentation of quarks in et- p collisions at HERA

    NASA Astrophysics Data System (ADS)

    Aid, S.; Andreev, V.; Andrieu, B.; Appuhn, R.-D.; Arpagaus, M.; Babaev, A.; Baehr, J.; Bán, J.; Ban, Y.; Baranov, P.; Barrelet, E.; Barschke, R.; Bartel, W.; Barth, M.; Bassler, U.; Beck, H. P.; Behrend, H.-J.; Belousov, A.; Berger, Ch.; Bernardi, G.; Bernet, R.; Bertrand-Coremans, G.; Besançon, M.; Beyer, R.; Biddulph, P.; Bispham, P.; Bizot, J. C.; Blobel, V.; Borras, K.; Botterweck, F.; Boudry, V.; Braemer, A.; Brasse, F.; Braunschweig, W.; Brisson, V.; Bruncko, D.; Brune, C.; Buchholz, R.; Büngener, L.; Bürger, J.; Büsser, F. W.; Buniatian, A.; Bürke, S.; Burton, M.; Buschhorn, G.; Campbell, A. J.; Carli, T.; Charles, F.; Charlet, M.; Clarke, D.; Clegg, A. B.; Clerbaux, B.; Colombo, M.; Contreras, J. G.; Cormack, C.; Coughlan, J. A.; Courau, A.; Coutures, Ch.; Cozzika, G.; Criegee, L.; Cussans, D. G.; Cvach, J.; Dagoret, S.; Dainton, J. B.; Dau, W. D.; Daum, K.; David, M.; Delcourt, B.; Del Buono, L.; De Roeck, A.; De Wolf, E. A.; Di Nezza, P.; Dollfus, C.; Dowell, J. D.; Dreis, H. B.; Droutskoi, A.; Duboc, J.; Düllmann, D.; Dünger, O.; Duhm, H.; Ebert, J.; Ebert, T. R.; Eckerlin, G.; Efremenko, V.; Egli, S.; Ehrlichmann, H.; Eichenberger, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellison, R. J.; Elsen, E.; Erdmann, M.; Erdmann, W.; Evrard, E.; Favart, L.; Fedotov, A.; Feeken, D.; Felst, R.; Feltesse, J.; Ferencei, J.; Ferrarotto, F.; Flamm, K.; Fleischer, M.; Flieser, M.; Flügge, G.; Fomenko, A.; Fominykh, B.; Forbush, M.; Formánek, J.; Foster, J. M.; Franke, G.; Fretwurst, E.; Gabathuler, E.; Gabathuler, K.; Gamerdinger, K.; Garvey, J.; Gayler, J.; Gebauer, M.; Gellrich, A.; Genzel, H.; Gerhards, R.; Goerlach, U.; Goerlach, L.; Gogitidze, N.; Goldberg, M.; Goldner, D.; Gonzalez-Pineiro, B.; Gorelov, I.; Goritchev, P.; Grab, C.; Grässler, H.; Grässler, R.; Greenshaw, T.; Grindhammer, G.; Gruber, A.; Gruber, C.; Haack, J.; Haidt, D.; Hajduk, L.; Hamon, O.; Hampel, M.; Hanlon, E. M.; Hapke, M.; Haynes, W. J.; Heatherington, J.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Herynek, I.; Hess, M. F.; Hildesheim, W.; Hill, P.; Hiller, K. H.; Hilton, C. D.; Hladký, J.; Hoeger, K. C.; Höppner, M.; Horisberger, R.; Hudgson, V. L.; Huet, Ph.; Hütte, M.; Hufnagel, H.; Ibbotson, M.; Itterbeck, H.; Jabiol, M.-A.; Jacholkowska, A.; Jacobsson, C.; Jaffre, M.; Janoth, J.; Jansen, T.; Jönson, L.; Johnson, D. P.; Johnson, L.; Jung, H.; Kalmus, P. I. P.; Kant, D.; Kaschowitz, R.; Kasselmann, P.; Kathage, U.; Katzy, J.; Kaufmann, H. H.; Kazarian, S.; Kenyon, I. R.; Kermiche, S.; Keuker, C.; Kiesling, C.; Klein, M.; Kleinwort, C.; Knies, G.; Ko, W.; Köhler, T.; Köhne, J. H.; Kolanoski, H.; Kole, F.; Kolya, S. D.; Korbel, V.; Korn, M.; Kostka, P.; Kotelnikov, S. K.; Krdmerkämper, T.; Krasny, M. W.; Krehbiel, H.; Krücker, D.; Krüger, U.; Krüner-Marquis, U.; Kubenka, J. P.; Küster, H.; Kuhlen, M.; Kurča, T.; Kurzhöfer, J.; Kuznik, B.; Lacour, D.; Lamarche, F.; Lander, R.; Landon, M. P. J.; Lange, W.; Lanius, P.; Laporte, J.-F.; Lebedev, A.; Leverenz, C.; Levonian, S.; Ley, Ch.; Lindner, A.; Lindström, G.; Link, J.; Linsel, F.; Lipinski, J.; List, B.; Lobo, G.; Loch, P.; Lohmander, H.; Lomas, J.; Lopez, G. C.; Lubimov, V.; Luke, D.; Magnussen, N.; Malinovski, E.; Mani, S.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martens, J.; Martin, R.; Martyn, H.-U.; Martyniak, J.; Masson, S.; Mavroidis, T.; Maxfield, S. J.; McMahon, S. J.; Mehta, A.; Meier, K.; Mercer, D.; Merz, T.; Meyer, C. A.; Meyer, H.; Meyer, J.; Migliori, A.; Mikocki, S.; Milstead, D.; Moreau, F.; Morris, J. V.; Mroczko, E.; Müller, G.; Müller, K.; Murín, P.; Nagovizin, V.; Nahnhauer, R.; Naroska, B.; Naumann, Th.; Newman, P. R.; Newton, D.; Neyret, D.; Nguyen, H. K.; Nicholls, T. C.; Niebergall, F.; Niebuhr, C.; Niedzballa, Ch.; Nisius, R.; Nowak, G.; Noyes, G. W.; Nyberg-Werther, M.; Oakden, M.; Oberlack, H.; Obrock, U.; Olsson, J. E.; Ozerov, D.; Panaro, E.; Panitch, A.; Pascaud, C.; Patel, G. D.; Peppel, E.; Perez, E.; Phillips, J. P.; Pichler, Ch.; Pieuchot, A.; Pitzl, D.; Pope, G.; Prell, S.; Prosi, R.; Rabbertz, K.; Radel, G.; Raupach, F.; Reimer, P.; Reinshagen, S.; Ribarics, P.; Rick, H.; Riech, V.; Riedlberger, J.; Riess, S.; Rietz, M.; Rizvi, E.; Robertson, S. M.; Robmann, P.; Roloff, H. E.; Roosen, R.; Rosenbauer, K.; Rostovtsev, A.; Rouse, F.; Royon, C.; Rütter, K.; Rusakov, S.; Rybicki, K.; Rylko, R.; Sahlmann, N.; Sanchez, E.; Sankey, D. P. C.; Schacht, P.; Schiek, S.; Schleper, P.; von Schlippe, W.; Schmidt, C.; Schmidt, D.; Schmidt, G.; Schöning, A.; Schröder, V.; Schuhmann, E.; Schwab, B.; Schwind, A.; Sefkow, F.; Seidel, M.; Sell, R.; Semenov, A.; Shekelyan, V.; Sheviakov, I.; Shooshtari, H.; Shtarkov, L. N.; Siegmon, G.; Siewert, U.; Sirois, Y.; Skillicorn, I. O.; Smirnov, P.; Smith, J. R.; Solochenko, V.; Soloviev, Y.; Spiekermann, J.; Spielman, S.; Spitzerx, H.; Starosta, R.; Steenbock, M.; Steffen, P.; Steinberg, R.; Stella, B.; Stephens, K.; Stier, J.; Stiewe, J.; Stosslein, U.; Stolze, K.; Strachota, J.; Straumann, U.; Struczinski, W.; Sutton, J. P.; Tapprogge, S.; Tchernyshov, V.; Thiebaux, C.; Thompson, G.; Truöl, P.; Turnau, J.; Tutas, J.; Uelkes, P.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; Van Esch, P.; Van Mechelen, P.; Vartapetian, A.; Vazdik, Y.; Verrecchia, P.; Villet, G.; Wacker, K.; Wagener, A.; Wagener, M.; Walker, I. W.; Walther, A.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wellisch, H. P.; West, L. R.; Willard, S.; Winde, M.; Winter, G.-G.; Wittek, C.; Wright, A. E.; Wünsch, E.; Wulff, N.; Yiou, T. P.; Žáček, J.; Zarbock, D.; Zhang, Z.; Zhokin, A.; Zimmer, M.; Zimmermann, W.; Zomer, F.; Zuber, K.; H1 Collaboration

    1995-02-01

    Deep inelastic scattering (DIS) events, selected from 1993 data taken by the H1 experiment at HERA, are studied in the Breit frame of reference. The fragmentation function of the quark is compared with those of e+e- data. It is shown that certain aspects of the quarks emerging from within the proton in e-p interactions are essentially the same as those of quarks pair-created from the vacuum in e+e- annihilation. The measured area, peak position and width of the fragmentation function show that the kinematic evolution variable, equivalent to the e+e- squared centre of mass energy, is in the Breit frame the invariant square of the four-momentum transfer. We comment on the extent to which we have evidence for coherence effects in pArton showers.

  4. Study of the fragmentation of /b quarks into /B mesons at the /Z peak

    NASA Astrophysics Data System (ADS)

    ALEPH Collaboration; Heister, A.; Schael, S.; Barate, R.; De Bonis, I.; Decamp, D.; Goy, C.; Lees, J.-P.; Merle, E.; Minard, M.-N.; Pietrzyk, B.; Bravo, S.; Casado, M. P.; Chmeissani, M.; Crespo, J. M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, L.; Graugés, E.; Martinez, M.; Merino, G.; Miquel, R.; Mir, L. M.; Pacheco, A.; Ruiz, H.; Colaleo, A.; Creanza, D.; de Palma, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Azzurri, P.; Boix, G.; Buchmüller, O.; Cattaneo, M.; Cerutti, F.; Clerbaux, B.; Dissertori, G.; Drevermann, H.; Forty, R. W.; Frank, M.; Greening, T. C.; Hansen, J. B.; Harvey, J.; Janot, P.; Jost, B.; Kado, M.; Mato, P.; Moutoussi, A.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Schneider, O.; Spagnolo, P.; Tejessy, W.; Teubert, F.; Tournefier, E.; Ward, J.; Ajaltouni, Z.; Badaud, F.; Falvard, A.; Gay, P.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Wäänänen, A.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G.; Brient, J.-C.; Rougé, A.; Rumpf, M.; Swynghedauw, M.; Verderi, M.; Videau, H.; Ciulli, V.; Focardi, E.; Parrini, G.; Antonelli, A.; Antonelli, M.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Chiarella, V.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Halley, A. W.; Lynch, J. G.; Negus, P.; O'Shea, V.; Raine, C.; Thompson, A. S.; Wasserbaech, S.; Cavanaugh, R.; Dhamotharan, S.; Geweniger, C.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Sommer, J.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Girone, M.; Marinelli, N.; Sedgbeer, J. K.; Thompson, J. C.; Ghete, V. M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bouhova-Thacker, E.; Bowdery, C. K.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Pearson, M. R.; Robertson, N. A.; Giehl, I.; Jakobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; Wachsmuth, H.; Zeitnitz, C.; Bonissent, A.; Carr, J.; Coyle, P.; Leroy, O.; Payre, P.; Rousseau, D.; Talby, M.; Aleppo, M.; Ragusa, F.; David, A.; Dietl, H.; Ganis, G.; Hüttmann, K.; Lütjens, G.; Mannert, C.; Männer, W.; Moser, H.-G.; Settles, R.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, P.; Jacholkowska, A.; Lefrançois, J.; Veillet, J.-J.; Videau, I.; Yuan, C.; Bagliesi, G.; Boccali, T.; Calderini, G.; Foà, L.; Giammanco, A.; Giassi, A.; Ligabue, F.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Sguazzoni, G.; Tenchini, R.; Venturi, A.; Verdini, P. G.; Blair, G. A.; Cowan, G.; Green, M. G.; Medcalf, T.; Misiejuk, A.; Strong, J. A.; Teixeira-Dias, P.; von Wimmersperg-Toeller, J. H.; Clifft, R. W.; Edgecock, T. R.; Norton, P. R.; Tomalin, I. R.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M.-C.; Locci, E.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Konstantinidis, N.; Litke, A. M.; Taylor, G.; Booth, C. N.; Cartwright, S.; Combley, F.; Lehto, M.; Thompson, L. F.; Affholderbach, K.; Böhrer, A.; Brandt, S.; Grupen, C.; Ngac, A.; Prange, G.; Sieler, U.; Giannini, G.; Rothberg, J.; Armstrong, S. R.; Cranmer, K.; Elmer, P.; Ferguson, D. P. S.; Gao, Y.; González, S.; Hayes, O. J.; Hu, H.; Jin, S.; Kile, J.; McNamara, P. A.; Nielsen, J.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Walsh, J.; Wu, S. L.; Wu, X.; Zobernig, G.

    2001-07-01

    The fragmentation of /b quarks into /B mesons is studied with four million hadronic /Z decays collected by the ALEPH experiment during the years 1991-1995. A semi-exclusive reconstruction of B-->lνD(*) decays is performed, by combining lepton candidates with fully reconstructed D(*) mesons while the neutrino energy is estimated from the missing energy of the event. The mean value of xBwd, the energy of the weakly-decaying /B meson normalised to the beam energy, is found to be =0.716+/-0.006(stat)+/-0.006(syst), using a model-independent method; the corresponding value for the energy of the leading /B meson is =0.736+/-0.006(stat)+/-0.006(syst). The reconstructed spectra are compared with different fragmentation models.

  5. Amplified fragment length polymorphism: an invaluable fingerprinting technique for genomic, transcriptomic, and epigenetic studies.

    PubMed

    Paun, Ovidiu; Schönswetter, Peter

    2012-01-01

    Amplified fragment length polymorphism (AFLP) is a PCR-based technique that uses selective amplification of a subset of digested DNA fragments to generate and compare unique fingerprints for genomes of interest. The power of this method relies mainly in that it does not require prior information regarding the targeted genome, as well as in its high reproducibility and sensitivity for detecting polymorphism at the level of DNA sequence. Widely used for plant and microbial studies, AFLP is employed for a variety of applications, such as to assess genetic diversity within species or among closely related species, to infer population-level phylogenies and biogeographic patterns, to generate genetic maps, and to determine relatedness among cultivars. Variations of standard AFLP methodology have been also developed for targeting additional levels of diversity, such as transcriptomic variation and DNA methylation polymorphism.

  6. Theoretical Studies of Gas Phase Elementary Reactions

    DTIC Science & Technology

    2009-11-30

    Application of Liouville -von Neumann Dynamics Method for Efficient Direct Dynamics Calculations; B. Development of Global Reaction Route Mapping (GRRM...Reactions of VX Agent. Accomplishments: A. Development and Application of Liouville -von Neumann Dynamics Method for Efficient Direct Dynamics...Calculations We developed a novel first principles Molecular Dynamics scheme, called LvNMD, based on the Liouville -von Neumann equation for density

  7. A recoil ion momentum spectrometer for molecular and atomic fragmentation studies

    SciTech Connect

    Khan, Arnab; Tribedi, Lokesh C.; Misra, Deepankar

    2015-04-15

    We report the development and performance studies of a newly built recoil ion momentum spectrometer for the study of atomic and molecular fragmentation dynamics in gas phase upon the impact of charged particles and photons. The present design is a two-stage Wiley-McLaren type spectrometer which satisfies both time and velocity focusing conditions and is capable of measuring singly charged ionic fragments up-to 13 eV in all directions. An electrostatic lens has been introduced in order to achieve velocity imaging. Effects of the lens on time-of-flight as well as on the position have been investigated in detail, both, by simulation and in experiment. We have used 120 keV proton beam on molecular nitrogen gas target. Complete momentum distributions and kinetic energy release distributions have been derived from the measured position and time-of-flight spectra. Along with this, the kinetic energy release spectra of fragmentation of doubly ionized nitrogen molecule upon various projectile impacts are presented.

  8. A recoil ion momentum spectrometer for molecular and atomic fragmentation studies

    NASA Astrophysics Data System (ADS)

    Khan, Arnab; Tribedi, Lokesh C.; Misra, Deepankar

    2015-04-01

    We report the development and performance studies of a newly built recoil ion momentum spectrometer for the study of atomic and molecular fragmentation dynamics in gas phase upon the impact of charged particles and photons. The present design is a two-stage Wiley-McLaren type spectrometer which satisfies both time and velocity focusing conditions and is capable of measuring singly charged ionic fragments up-to 13 eV in all directions. An electrostatic lens has been introduced in order to achieve velocity imaging. Effects of the lens on time-of-flight as well as on the position have been investigated in detail, both, by simulation and in experiment. We have used 120 keV proton beam on molecular nitrogen gas target. Complete momentum distributions and kinetic energy release distributions have been derived from the measured position and time-of-flight spectra. Along with this, the kinetic energy release spectra of fragmentation of doubly ionized nitrogen molecule upon various projectile impacts are presented.

  9. Studies on the biotin-binding site of avidin. Minimized fragments that bind biotin.

    PubMed

    Hiller, Y; Bayer, E A; Wilchek, M

    1991-09-01

    The object of this study was to define minimized biotin-binding fragments, or 'prorecognition sites', of either the egg-white glycoprotein avidin or its bacterial analogue streptavidin. Because of the extreme stability to enzymic hydrolysis, fragments of avidin were prepared by chemical means and examined for their individual biotin-binding capacity. Treatment of avidin with hydroxylamine was shown to result in new cleavage sites in addition to the known Asn-Gly cleavage site (position 88-89 in avidin). Notably, the Asn-Glu and Asp-Lys peptide bonds (positions 42-43 and 57-58 respectively) were readily cleaved; in addition, lesser levels of hydrolysis of the Gln-Pro (61-62) and Asn-Asp (12-13 and 104-105) bonds could be detected. The smallest biotin-binding peptide fragment, derived from hydroxylamine cleavage of either native or non-glycosylated avidin, was identified to comprise residues 1-42. CNBr cleavage resulted in a 78-amino acid-residue fragment (residues 19-96) that still retained activity. The data ascribe an important biotin-binding function to the overlapping region (residues 19-42) of avidin, which bears the single tyrosine moiety. This contention was corroborated by synthesizing a tridecapeptide corresponding to residues 26-38 of avidin; this peptide was shown to recognize biotin. Streptavidin was not susceptible to either enzymic or chemical cleavage methods used in this work. The approach taken in this study enabled the experimental distinction between the chemical and structural elements of the binding site. The capacity to assign biotin-binding activity to the tyrosine-containing domain of avidin underscores its primary chemical contribution to the binding of biotin by avidin.

  10. Studies on the biotin-binding site of avidin. Minimized fragments that bind biotin.

    PubMed Central

    Hiller, Y; Bayer, E A; Wilchek, M

    1991-01-01

    The object of this study was to define minimized biotin-binding fragments, or 'prorecognition sites', of either the egg-white glycoprotein avidin or its bacterial analogue streptavidin. Because of the extreme stability to enzymic hydrolysis, fragments of avidin were prepared by chemical means and examined for their individual biotin-binding capacity. Treatment of avidin with hydroxylamine was shown to result in new cleavage sites in addition to the known Asn-Gly cleavage site (position 88-89 in avidin). Notably, the Asn-Glu and Asp-Lys peptide bonds (positions 42-43 and 57-58 respectively) were readily cleaved; in addition, lesser levels of hydrolysis of the Gln-Pro (61-62) and Asn-Asp (12-13 and 104-105) bonds could be detected. The smallest biotin-binding peptide fragment, derived from hydroxylamine cleavage of either native or non-glycosylated avidin, was identified to comprise residues 1-42. CNBr cleavage resulted in a 78-amino acid-residue fragment (residues 19-96) that still retained activity. The data ascribe an important biotin-binding function to the overlapping region (residues 19-42) of avidin, which bears the single tyrosine moiety. This contention was corroborated by synthesizing a tridecapeptide corresponding to residues 26-38 of avidin; this peptide was shown to recognize biotin. Streptavidin was not susceptible to either enzymic or chemical cleavage methods used in this work. The approach taken in this study enabled the experimental distinction between the chemical and structural elements of the binding site. The capacity to assign biotin-binding activity to the tyrosine-containing domain of avidin underscores its primary chemical contribution to the binding of biotin by avidin. Images Fig. 1. Fig. 2. Fig. 3. Fig. 6. Fig. 7. Fig. 9. PMID:1898347

  11. VUV Photo-processing of PAH Cations: Quantitative Study on the Ionization versus Fragmentation Processes

    NASA Astrophysics Data System (ADS)

    Zhen, Junfeng; Rodriguez Castillo, Sarah; Joblin, Christine; Mulas, Giacomo; Sabbah, Hassan; Giuliani, Alexandre; Nahon, Laurent; Martin, Serge; Champeaux, Jean-Philippe; Mayer, Paul M.

    2016-05-01

    Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7-20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ˜13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies all species behave similarly; the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ˜18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them; all are in good agreement with theoretical ones, confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models.

  12. VUV photo-processing of PAH cations: quantitative study on the ionization versus fragmentation processes

    PubMed Central

    Zhen, Junfeng; Castillo, Sarah Rodriguez; Joblin, Christine; Mulas, Giacomo; Sabbah, Hassan; Giuliani, Alexandre; Nahon, Laurent; Martin, Serge; Champeaux, Jean-Philippe; Mayer, Paul M.

    2016-01-01

    Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7 – 20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ~13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies, all species behave similarly, the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ~18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section, but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them, all are in good agreement with theoretical ones confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models. PMID:27212712

  13. VUV photo-processing of PAH cations: quantitative study on the ionization versus fragmentation processes.

    PubMed

    Zhen, Junfeng; Castillo, Sarah Rodriguez; Joblin, Christine; Mulas, Giacomo; Sabbah, Hassan; Giuliani, Alexandre; Nahon, Laurent; Martin, Serge; Champeaux, Jean-Philippe; Mayer, Paul M

    2016-05-10

    Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7 - 20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ~13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies, all species behave similarly, the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ~18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section, but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them, all are in good agreement with theoretical ones confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models.

  14. A fragmentation study of kaempferol using electrospray quadrupole time-of-flight mass spectrometry at high mass resolution

    NASA Astrophysics Data System (ADS)

    March, Raymond E.; Miao, Xiu-Sheng

    2004-02-01

    A mass spectrometric method based on the combined use of electrospray ionization, collision-induced dissociation and tandem mass spectrometry at high mass resolution has been applied to an investigation of the structural characterization of protonated and deprotonated kaempferol (3,5,7,4'-tetrahydroxyflavone). Low-energy product ion mass spectra of [M+H]+ ions showed simple fragmentations of the C ring that permitted characterization of the substituents in the A and B rings. In addition, four rearrangement reactions accompanied by losses of C2H2O, CHO[radical sign], CO, and H2O were observed. Low-energy product ion mass spectra of [M-H]- ions showed only four rearrangement reactions accompanied by losses of OH[radical sign], CO, CH2O, and C2H2O. The use of elevated cone voltages permitted observation of product ion mass spectra of selected primary and secondary fragment ions so that each fragment ion reported was observed as a direct product of its immediate precursor ion. Product ion mass spectra examined at high mass resolution allowed unambiguous determination of the elemental composition of fragment ions and resolution of two pairs of isobars. Fragmentation mechanisms and ion structures have been proposed.

  15. Construction of a 3D-shaped, natural product like fragment library by fragmentation and diversification of natural products.

    PubMed

    Prescher, Horst; Koch, Guido; Schuhmann, Tim; Ertl, Peter; Bussenault, Alex; Glick, Meir; Dix, Ina; Petersen, Frank; Lizos, Dimitrios E

    2017-02-01

    A fragment library consisting of 3D-shaped, natural product-like fragments was assembled. Library construction was mainly performed by natural product degradation and natural product diversification reactions and was complemented by the identification of 3D-shaped, natural product like fragments available from commercial sources. In addition, during the course of these studies, novel rearrangements were discovered for Massarigenin C and Cytochalasin E. The obtained fragment library has an excellent 3D-shape and natural product likeness, covering a novel, unexplored and underrepresented chemical space in fragment based drug discovery (FBDD). Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Fragmentation of mercury compounds under ultraviolet light irradiation

    NASA Astrophysics Data System (ADS)

    Kokkonen, E.; Löytynoja, T.; Hautala, L.; Jänkälä, K.; Huttula, M.

    2015-08-01

    Ultraviolet light induced photofragmentation of mercury compounds is studied experimentally with electron energy resolved photoelectron-photoion coincidence techniques and theoretically with computational quantum chemical methods. A high resolution photoelectron spectrum using synchrotron radiation is presented. Fragmentation of the molecule is studied subsequent to ionization to the atomic-mercury-like d orbitals. State dependent fragmentation behaviour is presented and specific reactions for dissociation pathways are given. The fragmentation is found to differ distinctly in similar orbitals of different mercury compounds.

  17. Fragmentation of mercury compounds under ultraviolet light irradiation

    SciTech Connect

    Kokkonen, E.; Hautala, L.; Jänkälä, K.; Huttula, M.; Löytynoja, T.

    2015-08-21

    Ultraviolet light induced photofragmentation of mercury compounds is studied experimentally with electron energy resolved photoelectron-photoion coincidence techniques and theoretically with computational quantum chemical methods. A high resolution photoelectron spectrum using synchrotron radiation is presented. Fragmentation of the molecule is studied subsequent to ionization to the atomic-mercury-like d orbitals. State dependent fragmentation behaviour is presented and specific reactions for dissociation pathways are given. The fragmentation is found to differ distinctly in similar orbitals of different mercury compounds.

  18. Imidate-Based Cross-Linkers for Structural Proteomics: Increased Charge of Protein and Peptide Ions and CID and ECD Fragmentation Studies

    NASA Astrophysics Data System (ADS)

    Koolen, Hector H. F.; Gomes, Alexandre F.; Schwab, Nicolas V.; Eberlin, Marcos N.; Gozzo, Fabio C.

    2014-07-01

    Chemical cross-linking is an attractive low-resolution technique for structural studies of protein complexes. Distance constraints obtained from cross-linked peptides identified by mass spectrometry (MS) are used to construct and validate protein models. Amidinating cross-linkers such as diethyl suberthioimidate (DEST) have been used successfully in chemical cross-linking experiments. In this work, the application of a commercial diimidate cross-linking reagent, dimethyl suberimidate (DMS), was evaluated with model peptides and proteins. The peptides were designed with acetylated N-termini followed by random sequences containing two Lys residues separated by an Arg residue. After cross-linking reactions, intra- and intermolecular cross-linked species were submitted to CID and ECD dissociations to study their fragmentation features in the gas phase. Fragmentation of intramolecular peptides by collision induced dissociation (CID) demonstrates a unique two-step fragmentation pathway involving formation of a ketimine as intermediate. Electron capture and electron transfer dissociation (ECD and ETD) experiments demonstrated that the cyclic moiety is not dissociated. Intermolecular species demonstrated previously described fragmentation behavior in both CID and ECD experiments. The charge state distributions (CSD) obtained after reaction with DMS were compared with those obtained with disuccinimidyl suberate (DSS). CSDs for peptides and proteins were increased after their reaction with DMS, owing to the higher basicity of DMS modified species. These features were also observed in LC-MS experiments with bovine carbonic anhydrase II (BCA) after cross-linking with DMS and tryptic proteolysis. Cross-linked peptides derived from this protein were identified at high confidence and those species were in agreement with the crystal structure of BCA.

  19. Development of a polymerase chain reaction-restriction fragment length polymorphism method for identification of the Fusarium genus using the transcription elongation factor-1α gene.

    PubMed

    Zarrin, Majid; Ganj, Farzaneh; Faramarzi, Sama

    2016-12-01

    Fusarium species are well-known plant pathogens and food contaminants that have also appeared as one of the most important groups of medically significant fungi. The sequences of the translation elongation factor (TEF)-1α gene have been broadly employed for species detection. A total of 50 strains of Fusarium spp., including environmental, clinical and reference isolates were used for the current study. The primer sets, Fu3f and Fu3r, were used to amplify an ~420-bp DNA fragment of the TEF-1α gene. Double digestion with two restriction enzymes, XhoI and SduI was used for discrimination of the Fusarium species in the TEF-1α gene fragment. Double digestion of the TEF-1α gene fragment from five clinically important Fusarium species were clearly differentiated from each other: The F. solani species complex, F. oxysporum species complex, F. verticillioides, F. proliferatum and F. fujikuroi. This method facilitates detection and enables verification of the Fusarium genus; therefore, it may be applied for disease control.

  20. Development of a polymerase chain reaction-restriction fragment length polymorphism method for identification of the Fusarium genus using the transcription elongation factor-1α gene

    PubMed Central

    Zarrin, Majid; Ganj, Farzaneh; Faramarzi, Sama

    2016-01-01

    Fusarium species are well-known plant pathogens and food contaminants that have also appeared as one of the most important groups of medically significant fungi. The sequences of the translation elongation factor (TEF)-1α gene have been broadly employed for species detection. A total of 50 strains of Fusarium spp., including environmental, clinical and reference isolates were used for the current study. The primer sets, Fu3f and Fu3r, were used to amplify an ~420-bp DNA fragment of the TEF-1α gene. Double digestion with two restriction enzymes, XhoI and SduI was used for discrimination of the Fusarium species in the TEF-1α gene fragment. Double digestion of the TEF-1α gene fragment from five clinically important Fusarium species were clearly differentiated from each other: The F. solani species complex, F. oxysporum species complex, F. verticillioides, F. proliferatum and F. fujikuroi. This method facilitates detection and enables verification of the Fusarium genus; therefore, it may be applied for disease control. PMID:28105337

  1. Experimental verification of proton beam monitoring in a human body by use of activity image of positron-emitting nuclei generated by nuclear fragmentation reaction.

    PubMed

    Nishio, Teiji; Miyatake, Aya; Inoue, Kazumasa; Gomi-Miyagishi, Tomoko; Kohno, Ryosuke; Kameoka, Satoru; Nakagawa, Keiichi; Ogino, Takashi

    2008-01-01

    Proton therapy is a form of radiotherapy that enables concentration of dose on a tumor by use of a scanned or modulated Bragg peak. Therefore, it is very important to evaluate the proton-irradiated volume accurately. The proton-irradiated volume can be confirmed by detection of pair-annihilation gamma rays from positron-emitting nuclei generated by the nuclear fragmentation reaction of the incident protons on target nuclei using a PET apparatus. The activity of the positron-emitting nuclei generated in a patient was measured with a PET-CT apparatus after proton beam irradiation of the patient. Activity measurement was performed in patients with tumors of the brain, head and neck, liver, lungs, and sacrum. The 3-D PET image obtained on the CT image showed the visual correspondence with the irradiation area of the proton beam. Moreover, it was confirmed that there were differences in the strength of activity from the PET-CT images obtained at each irradiation site. The values of activity obtained from both measurement and calculation based on the reaction cross section were compared, and it was confirmed that the intensity and the distribution of the activity changed with the start time of the PET imaging after proton beam irradiation. The clinical use of this information about the positron-emitting nuclei will be important for promoting proton treatment with higher accuracy in the future.

  2. School Social Fragmentation, Economic Deprivation and Social Cohesion and Adolescent Physical Inactivity: A Longitudinal Study

    PubMed Central

    Pabayo, Roman; Janosz, Michel; Bisset, Sherri; Kawachi, Ichiro

    2014-01-01

    Objectives To examine the independent influence of school economic deprivation, social fragmentation, and social cohesion on the likelihood of participating in no physical activity among students. Methods Data are from a large-scale longitudinal study of schools based in disadvantaged communities in Quebec, Canada. Questionnaires were administered every year between 2002 and 2008 among n = 14,924 students aged 12 to 18 from a sample of 70 schools. Cross-sectional and longitudinal analyses were conducted. Multilevel modeling was utilized to account for the clustering of students within schools. Schools were categorized as being low, moderate or high economic deprivation, social fragmentation and social cohesion. Those who indicated that they do no participate in any physical activity during the week were identified as being physically inactive. Results In baseline multilevel cross-sectional analyses, adolescents attending schools in the highest (compared to the lowest) levels of socioeconomic deprivation and social fragmentation were more likely to be physically inactive (OR = 1.33, 95% CI = 1.03, 1.72; and OR = 1.24, 95% CI = 0.98, 1.56, respectively). Conversely, students attending schools with the highest cohesion were less likely to be physically inactive (OR = 0.78, 95% CI = 0.61, 0.99). In longitudinal analysis, physically active students who attended schools with the highest social fragmentation were more likely to become physically inactive over two years (OR = 1.65, 95% CI = 1.09, 2.51). Conclusion The school socioeconomic environment appears to be an important contextual influence on participation in no physical activity among adolescents. Following adolescents beyond two years is necessary to determine if these environments have a lasting effect on physical activity behavior. PMID:24932679

  3. School social fragmentation, economic deprivation and social cohesion and adolescent physical inactivity: a longitudinal study.

    PubMed

    Pabayo, Roman; Janosz, Michel; Bisset, Sherri; Kawachi, Ichiro

    2014-01-01

    To examine the independent influence of school economic deprivation, social fragmentation, and social cohesion on the likelihood of participating in no physical activity among students. Data are from a large-scale longitudinal study of schools based in disadvantaged communities in Quebec, Canada. Questionnaires were administered every year between 2002 and 2008 among n = 14,924 students aged 12 to 18 from a sample of 70 schools. Cross-sectional and longitudinal analyses were conducted. Multilevel modeling was utilized to account for the clustering of students within schools. Schools were categorized as being low, moderate or high economic deprivation, social fragmentation and social cohesion. Those who indicated that they do no participate in any physical activity during the week were identified as being physically inactive. In baseline multilevel cross-sectional analyses, adolescents attending schools in the highest (compared to the lowest) levels of socioeconomic deprivation and social fragmentation were more likely to be physically inactive (OR = 1.33, 95% CI = 1.03, 1.72; and OR = 1.24, 95% CI = 0.98, 1.56, respectively). Conversely, students attending schools with the highest cohesion were less likely to be physically inactive (OR = 0.78, 95% CI = 0.61, 0.99). In longitudinal analysis, physically active students who attended schools with the highest social fragmentation were more likely to become physically inactive over two years (OR = 1.65, 95% CI = 1.09, 2.51). The school socioeconomic environment appears to be an important contextual influence on participation in no physical activity among adolescents. Following adolescents beyond two years is necessary to determine if these environments have a lasting effect on physical activity behavior.

  4. A statistical study of meteoroid fragmentation and differential ablation using the Resolute Bay Incoherent Scatter Radar

    NASA Astrophysics Data System (ADS)

    Malhotra, Akshay; Mathews, John D.

    2011-04-01

    There has been much interest in the meteor physics community recently regarding the detailed processes by which the meteoroid mass flux arrives in the upper atmosphere. Of particular interest are the relative roles of simple ablation, differential ablation, and fragmentation in interpretation of the meteor events observed by the high-power large-aperture (HPLA) radars. An understanding of the relative roles of these mechanisms is necessary to determine whether the considerable meteor mass flux arriving in the upper atmosphere arrives mostly in nanometer dust/smoke (via fragmentation) or atomic form (via ablation), which in turn has important consequences in understanding not only the aeronomy of the region but also the formation and evolution of various upper atmospheric phenomenon such as Polar Mesospheric Summer Echoes. Using meteor observations from the newly operational Resolute Bay Incoherent Scatter Radar (RISR), we present the first statistical study showing the relative contribution of these mechanisms. We find that RISR head echoes exhibited ˜48% fragmentation, ˜32% simple ablation, and ˜20% differential ablation. We also report existence of compound meteor events exhibiting signatures of more than one mass loss mechanism. These results emphasize that the processes by which the meteoroid mass is deposited into the upper atmosphere are complex and involve all three mechanisms described here. This conclusion is unlike the previously reported results that stress the importance of one or the other of these mechanisms. These results will also contribute in improving current meteoroid disintegration/ablation models.

  5. Experimental and numerical study of thin fragments protection for radiographic detectors

    NASA Astrophysics Data System (ADS)

    Bozier, Olivier; Counilh, Denis; Gillot, Fabrice; Adolf, Lise-Marie; Silvin, Pascale; Rambert, Nicolas; Hebert, David; Bertron, Isabelle

    2015-06-01

    To perform a non-intrusive measurement on a pyrotechnic setup, we usually use radiography. But due to blast and fragments, the X-ray generator head and the detectors of the radiographic chain must be protected. Since the detector holds the data we want to collect, he cannot be sacrificed. The constitution of detector shielding is therefore an essential part of a radiographic chain. The choice of shielding should take into account two conflicting needs. On one hand, shielding must be sufficiently resistant to protect the detector from the blast and fragments generated. On the other hand, it should be thin enough in order to attenuate as little as possible the radiographic signal. We carried out an experimental campaign to test the performances of various shieldings. Cylindrical projectiles of various masses (from 20g to 40g) and aspect ratios (length to diameter ratio from 0.1 to 1) that are representative fragments, have been launched with a gas gun with different initial velocities (from 1500m/s up to 2000m/s). Multiple shielding configurations have been tested. They were assemblies of successive steel, aluminum and B4C plates. Combined with a numerical study, we optimize disposition and thicknesses of the plates which fulfils our requirements in terms of detector protection and radiographic measurement.

  6. Studies of fission fragment properties at the Los Alamos Neutron Science Center (LANSCE)

    NASA Astrophysics Data System (ADS)

    Tovesson, Fredrik; Mayorov, Dmitriy; Duke, Dana; Manning, Brett; Geppert-Kleinrath, Verena

    2017-09-01

    Nuclear data related to the fission process are needed for a wide variety of research areas, including fundamental science, nuclear energy and non-proliferation. While some of the relevant data have been measured to the required accuracies there are still many aspects of fission that need further investigation. One such aspect is how Total Kinetic Energy (TKE), fragment yields, angular distributions and other fission observables depend on excitation energy of the fissioning system. Another question is the correlation between mass, charge and energy of fission fragments. At the Los Alamos Neutron Science Center (LANSCE) we are studying neutron-induced fission at incident energies from thermal up to hundreds of MeV using the Lujan Center and Weapons Neutron Research (WNR) facilities. Advanced instruments such as SPIDER (time-of-flight and kinetic energy spectrometer), the NIFFTE Time Projection Chamber (TPC), and Frisch grid Ionization Chambers (FGIC) are used to investigate the properties of fission fragments, and some important results for the major actinides have been obtained.

  7. Fragmentation and conformation study of ephedrine by low- and high-resolution mass selective UV spectroscopy

    NASA Astrophysics Data System (ADS)

    Chervenkov, S.; Wang, P. Q.; Braun, J. E.; Neusser, H. J.

    2004-10-01

    The neurotransmitter molecule, ephedrine, has been studied by mass-selective low- and high-resolution UV resonance enhanced two-photon ionization spectroscopy. Under all experimental conditions we observed an efficient fragmentation upon ionization. The detected vibronic peaks in the spectrum are classified according to the efficiency of the fragmentation, which leads to the conclusion that there exist three different species in the molecular beam: ephedrine-water cluster and two distinct conformers. The two-color two-photon ionization experiment with a decreased energy of the second photon leads to an upper limit of 8.3 eV for the ionization energy of ephedrine. The high-resolution (70 MHz) spectrum of the strongest vibronic peak in the spectrum measured at the fragment (m/z=58) mass channel displays a pronounced and rich rotational structure. Its analysis by the use of a specially designed computer-aided rotational fit process yields accurate rotational constants for the S0 and S1 states and the transition moment ratio, providing information on the respective conformational structure.

  8. Study of char gasification in a reaction/adsorption apparatus

    SciTech Connect

    Sotirchos, S.V.; Crowley, J.A.

    1987-09-01

    The reaction of an activated carbon (coconut char) with CO/sub 2/ was studied in a reaction/adsorption apparatus which allows successive reactivity and physical adsorption measurements to be made on the same solid sample. Reaction and surface area evolution data were obtained in the temperature range from 800 to 900/sup 0/C. All reaction rate trajectories obtained in this study showed a maximum in the reaction rate, 2-3 times higher than the initial rate, at about 85% conversion. There was no correlation between these results and the evolution of the internal surface area although the reaction appeared to take place initially in the kinetically controlled regime.

  9. Fragmentation Processes

    NASA Astrophysics Data System (ADS)

    Whelan, Colm T.

    2012-12-01

    Preface; 1. Direct and resonant double-photoionization: from atoms to solids L. Avaldi and G. Stefani; 2. The application of propagation exterior complex scaling to atomic collisions P. L. Bartlett and A. T. Stelbovics; 3. Fragmentation of molecular-ion beams in intense ultra-short laser pulses I. Ben-Itzhak; 4. Atoms with one and two active electrons in strong laser fields I. A. Ivanov and A. S. Kheifets; 5. Experimental aspects of ionization studies by positron and positronium impact G. Laricchia, D. A. Cooke, Á. Kövér and S. J. Brawley; 6. (e,2e) spectroscopy using fragmentation processes J. Lower, M. Yamazaki and M. Takahashi; 7. A coupled pseudostate approach to the calculation of ion-atom fragmentation processes M. McGovern, H. R. J. Walters and C. T. Whelan; 8. Electron Impact Ionization using (e,2e) coincidence techniques from threshold to intermediate energies A. J. Murray; 9. (e,2e) processes on atomic inner shells C. T. Whelan; 10. Spin resolved atomic (e,2e) processes J. Lower and C. T. Whelan; Index.

  10. STUDIES ON THE GENERALIZED SHWARTZMAN REACTION

    PubMed Central

    Good, Robert A.; Thomas, Lewis

    1952-01-01

    Intravenous injection of thorotrast or trypan blue rendered rabbits susceptible to the production of bilateral cortical necrosis of the kidneys by a single intravenous injection of small amounts of meningococcal or Serratia marcescens toxin. This reaction was not produced when thorotrast or trypan blue were injected after toxin had been given. A single intradermal injection of toxin produced hemorrhagic skin lesions resembling the local Shwartzman reaction in rabbits given thorotrast 6 hours previously. These animals also developed bilateral cortical necrosis of the kidneys. When the order of injection was reversed, and thorotrast given after toxin, neither skin nor kidney lesions occurred. The skin and kidney lesions in thorotrast-treated rabbits were, like the local and generalized Shwartzman reactions, completely prevented by treatment with nitrogen mustard, in doses sufficient to produce polymorphonuclear leukopenia. The significance of these reactions, and their relationship to the previously described response to toxin in cortisone-treated rabbits, are discussed. PMID:13022855

  11. Explore the reaction mechanism of the Maillard reaction: a density functional theory study.

    PubMed

    Ren, Ge-Rui; Zhao, Li-Jiang; Sun, Qiang; Xie, Hu-Jun; Lei, Qun-Fang; Fang, Wen-Jun

    2015-05-01

    The mechanism of Maillard reaction has been investigated by means of density functional theory calculations in the gaseous phase and aqueous solution. The Maillard reaction is a cascade of consecutive and parallel reaction. In the present model system study, glucose and glycine were taken as the initial reactants. On the basis of previous experimental results, the mechanisms of Maillard reaction have been proposed, and the possibility for the formation of different compounds have been evaluated through calculating the relative energy changes for different steps of reaction under different pH conditions. Our calculations reveal that the TS3 in Amadori rearrangement reaction is the rate-determining step of Maillard reaction with the activation barriers of about 66.7 and 68.8 kcal mol(-1) in the gaseous phase and aqueous solution, respectively. The calculation results are in good agreement with previous studies and could provide insights into the reaction mechanism of Maillard reaction, since experimental evaluation of the role of intermediates in the Maillard reaction is quite complicated.

  12. Characteristics of vestibulosensory reactions studied by experimental caloric test

    NASA Technical Reports Server (NTRS)

    Kapranov, V. Z.

    1980-01-01

    Vestibulo-sensory reactions were studied in 135 workers who were in contact with nitroethers, by the method of an experimental caloric test. The response vestibulo-sensory reactions were recorded by means of an electroencephalograph. The changes in the sensory reaction depended on the duration of the workers' contact with toxic agents. A study of illusion reactions by the labyrinth calorization widens diagnostic possibilities in the examination of functional condition of the vestibular analyser considerably.

  13. Density functional study of chemical reaction equilibrium for dimerization reactions in slit and cylindrical nanopores

    NASA Astrophysics Data System (ADS)

    Malijevský, Alexandr; Lísal, Martin

    2009-04-01

    We present a theoretical study of the effects of confinement on chemical reaction equilibrium in slit and cylindrical nanopores. We use a density functional theory (DFT) to investigate the effects of temperature, pore geometry, bulk pressure, transition layering, and capillary condensation on a dimerization reaction that mimics the nitric oxide dimerization reaction, 2NO⇌(NO)2, in carbonlike slit and cylindrical nanopores in equilibrium with a vapor reservoir. In addition to the DFT calculations, we also utilize the reaction ensemble Monte Carlo method to supplement the DFT results for reaction conversion. This work is an extension of the previous DFT study by Tripathi and Chapman [J. Chem. Phys. 118, 7993 (2003)] on the dimerization reactions confined in the planar slits.

  14. Laser studies of chemical reaction and collision processes

    SciTech Connect

    Flynn, G.

    1993-12-01

    This work has concentrated on several interrelated projects in the area of laser photochemistry and photophysics which impinge on a variety of questions in combustion chemistry and general chemical kinetics. Infrared diode laser probes of the quenching of molecules with {open_quotes}chemically significant{close_quotes} amounts of energy in which the energy transferred to the quencher has, for the first time, been separated into its vibrational, rotational, and translational components. Probes of quantum state distributions and velocity profiles for atomic fragments produced in photodissociation reactions have been explored for iodine chloride.

  15. Soot Reaction Properties (Ground-Based Study)

    NASA Technical Reports Server (NTRS)

    Dai, Z.; El-Leathy, A. M.; Lin, K.-C.; Sunderland, P. B.; Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

    2000-01-01

    Three major soot reaction processes are needed to predict soot properties in flame environments: soot growth, or the formation of soot on soot nuclei and soot particles; soot oxidation, or the reaction of soot with oxidizing species to yield the combustion products of soot oxidation; and soot nucleation, or the formation of soot nuclei from soot precursors having large molecular weights (generally thought to be large and particularly stable PAH molecules in flame environments, called stabilomers). These processes are addressed in the following, considering soot growth, oxidation and nucleation, in turn, by exploiting the soot and flame structure results for premixed and diffusion flames already discussed in Section 2.

  16. Raman spectroscopic study of reaction dynamics

    NASA Astrophysics Data System (ADS)

    MacPhail, R. A.

    1990-12-01

    The Raman spectra of reacting molecules in liquids can yield information about various aspects of the reaction dynamics. The author discusses the analysis of Raman spectra for three prototypical unimolecular reactions, the rotational isomerization of n-butane and 1,2-difluoroethane, and the barrierless exchange of axial and equatorial hydrogens in cyclopentane via pseudorotation. In the first two cases the spectra are sensitive to torsional oscillations of the gauche conformer, and yield estimates of the torsional solvent friction. In the case of cyclopentane, the spectra can be used to discriminate between different stochastic models of the pseudorotation dynamics, and to determine the relevant friction coefficients.

  17. Isolation of Coxiella burnetii by a centrifugation shell-vial assay from ticks collected in Cyprus: detection by nested polymerase chain reaction (PCR) and by PCR-restriction fragment length polymorphism analyses.

    PubMed

    Spyridaki, Ioanna; Psaroulaki, Anna; Loukaides, Fidias; Antoniou, Maria; Hadjichristodolou, Christos; Tselentis, Yannis

    2002-01-01

    Ticks are the principal vectors and reservoirs of Coxiella burnetii. The identification of isolates is necessary for understanding the clinical diversity of Q fever in different geographic areas. This is the first report of isolation of C. burnetii from ticks by the shell-vial assay and by nested polymerase chain reaction (PCR) assay for the detection of this pathogen in ticks. Of 141 ticks collected in Cyprus (Rhipicephalus sanguineus and Hyalloma spp.), 10% were found to be infected with C. burnetii. Three ticks were positive by hemolymph test, and 11 triturated ticks were positive by nested PCR. Three isolates were obtained by the centrifugation shell-vial technique. Analysis by PCR, then restriction fragment length polymorphism showed that the 3 Cyprus isolates had identical restriction profiles to reference strains Nine Mile and Q212. The methods described are useful in studying the epidemiology and ecology of C. burnetii.

  18. Development of a Multiplexed Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) Assay to Identify Common Members of the Subgenera Culex (Culex) and Culex (Phenacomyia) in Guatemala

    PubMed Central

    Kent, Rebekah J.; Deus, Stephen; Williams, Martin; Savage, Harry M.

    2010-01-01

    Morphological differentiation of mosquitoes in the subgenera Culex (Culex) and Culex (Phenacomyia) in Guatemala is difficult, with reliable identification ensured only through examination of larval skins from individually reared specimens and associated male genitalia. We developed a multiplexed polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay to identify common Cx. (Cux.) and Cx. (Phc.). Culex (Cux.) chidesteri, Cx. (Cux.) coronator, Cx. (Cux.) interrogator, Cx. (Cux.) quinquefasciatus, Cx. (Cux.) nigripalpus/Cx. (Cux.) thriambus, and Cx. (Phc.) lactator were identified directly with a multiplexed primer cocktail comprising a conserved forward primer and specific reverse primers targeting ribosomal DNA (rDNA). Culex nigripalpus and Cx. thriambus were differentiated by restriction digest of homologous amplicons. The assay was developed and optimized using well-characterized specimens from Guatemala and the United States and field tested with unknown material from Guatemala. This assay will be a valuable tool for mosquito identification in entomological and arbovirus ecology studies in Guatemala. PMID:20682869

  19. Identification of brucella species and biotypes using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

    PubMed

    Al Dahouk, Sascha; Tomaso, Herbert; Prenger-Berninghoff, Ellen; Splettstoesser, Wolf D; Scholz, Holger C; Neubauer, Heinrich

    2005-01-01

    Brucellosis is a worldwide zoonosis causing reproductive failures in livestock and a severe multi-organ disease in humans. The genus Brucella is divided into seven species and various biotypes differing in pathogenicity and host specificity. Although Brucella spp. represent a highly homogenous group of bacteria, RFLPs of selected genes display sufficient polymorphism to distinguish Brucella species and biovars. PCR-RFLP analysis shows excellent typeability, reproducibility, stability, and epidemiological concordance. Consequently, PCR-RFLP assays of specific gene loci can serve as tools for diagnostic, epidemiological, taxonomic, and evolutionary studies. Various PCR-RFLPs used for the identification of Brucella species and biotypes are reviewed.

  20. Studies on energy-linked reactions. Energy-linked transhydrogenase reaction in Escherichia coli

    PubMed Central

    Sweetman, A. J.; Griffiths, D. E.

    1971-01-01

    1. Small particles from Escherichia coli catalyse an ATP-dependent reduction of NADP+ by NADH. 2. The reaction was stimulated by Mg2+ and only ATP and ITP could serve as energy donors. 3. Studies of the stoicheiometry of the reaction indicate that 1–2mol of ATP are utilized/mol of NADH produced. 4. The reaction is inhibited by uncoupling agents such as 2,4-dinitrophenol (200μm) and tetrachlorotrifluorobenzimidazole (2μm) but oligomycin does not inhibit. 5. The reaction is inhibited by relatively high concentrations (200μm) of piericidin A. PMID:4398957

  1. Kinetic Study of the Heck Reaction: An Interdisciplinary Experiment

    ERIC Educational Resources Information Center

    Gozzi, Christel; Bouzidi, Naoual

    2008-01-01

    The aim of this experiment is to study and calculate the kinetic constant of a Heck reaction: the arylation of but-3-en-2-ol by iodobenzene catalyzed by palladium acetate in presence of triethylamine in DMF. The reaction leads to a mixture of two ketones. Students use GC analysis to quantify reagents and products of reaction. They control the…

  2. Kinetic Study of the Heck Reaction: An Interdisciplinary Experiment

    ERIC Educational Resources Information Center

    Gozzi, Christel; Bouzidi, Naoual

    2008-01-01

    The aim of this experiment is to study and calculate the kinetic constant of a Heck reaction: the arylation of but-3-en-2-ol by iodobenzene catalyzed by palladium acetate in presence of triethylamine in DMF. The reaction leads to a mixture of two ketones. Students use GC analysis to quantify reagents and products of reaction. They control the…

  3. An Ecological Study of Social Fragmentation, Socioeconomic Deprivation, and Suicide in Rural China: 2008-2010.

    PubMed

    Li, Lydia W; Xu, Hongwei; Zhang, Zhenmei; Liu, Jinyu

    2016-12-01

    China accounts for a large number of suicides worldwide, and most occur in rural areas. Suicide research in China has primarily focused on individual-level risk factors, few have studied the influence of neighborhood contexts. This ecological study examines the association of suicide rates with social fragmentation and socioeconomic deprivation in Chinese rural villages. Data from the community survey of the China Health and Retirement Longitudinal Study were analyzed using negative binomial regression. A total of 307 rural villages were included. The community survey collected data about the villages from local leaders. Suicide counts were measured by the leaders' report of the number of suicide deaths in the villages. Social fragmentation was indicated by out-migration, in-migration and ethnic diversity; socioeconomic deprivation was indicated by physical infrastructure, illiteracy rates and public transit accessibility. The results show that higher incidence rates of suicide occurred in villages with high proportions of out-migration (vs. low), inflow of migrants (vs. no migrants), mixes of Han and ethnic minority residents (vs. Han only), high degrees of infrastructure deficiency (vs. low) and poor access to public transportation (vs. excellent). Villages with higher percentages of older adults also had higher suicide rates. This is one of the first studies to examine the association between neighborhood contexts and suicide in China. The findings have implications for suicide prevention in rural China.

  4. Study of Reaction Mechanism in Tracer Munitions

    DTIC Science & Technology

    1974-12-01

    Regression Rates (Furnished by Frankford Arsenal) 35 13 Calculated Heat Fluxes and Energy Partitions 43 4 I NOMENCLATURE B = preexponential factor... anhydride disproportionates in a fast step: N2 0 3 - 2 + NO (4) so that the resulting dioxide can react with more nitrite in another fast reaction: Sr

  5. Physical and dynamical studies of meteors. Meteor-fragmentation and stream-distribution studies

    NASA Technical Reports Server (NTRS)

    Sekanina, Z.; Southworth, R. B.

    1975-01-01

    Population parameters of 275 streams including 20 additional streams in the synoptic-year sample were found by a computer technique. Some 16 percent of the sample is in these streams. Four meteor streams that have close orbital resemblance to Adonis cannot be positively identified as meteors ejected by Adonis within the last 12000 years. Ceplecha's discrete levels of meteor height are not evident in radar meteors. The spread of meteoroid fragments along their common trajectory was computed for most of the observed radar meteors. There is an unexpected relationship between spread and velocity that perhaps conceals relationships between fragmentation and orbits; a theoretical treatment will be necessary to resolve these relationships. Revised unbiased statistics of synoptic-year orbits are presented, together with parallel statistics for the 1961 to 1965 radar meteor orbits.

  6. A DNA logic gate based on strand displacement reaction and rolling circle amplification, responding to multiple low-abundance DNA fragment input signals, and its application in detecting miRNAs.

    PubMed

    Chen, Yuqi; Song, Yanyan; Wu, Fan; Liu, Wenting; Fu, Boshi; Feng, Bingkun; Zhou, Xiang

    2015-04-25

    A conveniently amplified DNA AND logic gate platform was designed for the highly sensitive detection of low-abundance DNA fragment inputs based on strand displacement reaction and rolling circle amplification strategy. Compared with others, this system can detect miRNAs in biological samples. The success of this strategy demonstrates the potential of DNA logic gates in disease diagnosis.

  7. Antibody fragment recognition layers for surface plasmon resonance biosensing: a parametric study

    NASA Astrophysics Data System (ADS)

    Magalhães, André; Bordeira, Sandro; Almeida, Ana Cristina; Fontes, Vanessa; Costa, Maria João L.; Fonseca, Luís P.; da Fonseca, João Garcia

    2009-02-01

    A comparative study is reported regarding the use of two different surface plasmon resonance (SPR) biosensors, a homemade SPR grating biosensor and a reference prism coupled biosensor, to perform quantification of C-reactive protein (CRP) in human blood serum. Surface functionalization was conducted using anti-CRP fragments immobilized directly on gold. Adsorption time optimization for the antibody fragments monolayer, non-specific binding (NSB) resistance evaluation and CRP detection were conducted, with better results achieved by the grating biosensor on all topics, namely less functionalization time, higher resistance to NSB and wider CRP dynamic concentration range. A study regarding comparison between continuous flow and surface coating immobilization is also reported in this work. We have shown that surface coating immobilization achieves similar NSB resistance and CRP detection results, allowing a 75% assay cost reduction by lower solution volume requirement. Results suggest that the coating immobilization technique is the best suited to be used in further studies in order to obtain a viable immunosensor for CRP and other biomarkers detection in complex biological fluids.

  8. Polymerase chain reaction-restriction fragment length polymorphism of the rpoB gene for identification of Mycobacterium avium subsp. paratuberculosis and differentiation of Mycobacterium avium subspecies.

    PubMed

    Whang, Jake; Lee, Byung Soo; Choi, Go-Eun; Cho, Sang-Nae; Kil, Park Young; Collins, Michael T; Shin, Sung Jae

    2011-05-01

    Mycobacterial speciation by polymerase chain reaction (PCR)-restriction fragment length polymorphism analysis (PRA) of the rpoB gene was evaluated for identification of Mycobacterium avium subsp. paratuberculosis (MAP) and other Mycobacterium avium complex (MAC) members to the species or subspecies level by comparison with conventional methods including hsp65 sequencing, high-performance liquid chromatography, and PCR for accepted species- or subspecies-specific genomic targets. A total of 185 type and clinical mycobacterial strains from humans, animals, and environments were tested. A 360-bp PCR product was subsequently digested with MspI, HaeIII, and SmaI restriction enzymes. The PRA using SmaI restriction showed a unique digestion pattern for MAP distinguishing it from other MAC members and other Mycobacterium spp. Moreover, HaeIII and MspI restriction of the rpoB gene enabled MAC-species and -subspecies discrimination. The rpoB-PRA using SmaI or MspI and HaeIII restriction of the rpoB gene is a simple, convenient, and reliable confirmatory assay for simultaneous identification of MAP and other MAC members.

  9. Molecular identification of nine commercial flaffish species by polymerase chain reaction-restriction fragment length polymorphism analysis of a segment of the cytochrome b region.

    PubMed

    Sanjuan, Andrés; Comesaña, Angel S

    2002-06-01

    Commercial refrigerated or frozen flatfish fillets are sometimes mislabeled, and identification of these mislabeled products is necessary to prevent fraudulent substitution. Identification of nine commercial flatfish species (order Pleuronectiformes), Hippoglossus hippoglossus (halibut), Lepidorhombus boscii (four-spotted scaldfish), Lepidorhombus whiffiagonis (megrin), Platichthys flesus (flounder), Pleuronectes platessa (European plaice), Reinhardtius hippoglossoides (Greenland halibut), Scophthalmus maximus (turbot), Scophthalmus rhombus (brill), and Solea vulgaris (=Solea solea) (sole), was carried out on the basis of the amplification of a 486-bp segment of the mitochondrial genome (tRNA(Glu)/cytochrome b) by using the polymerase chain reaction (PCR) and universal primers. Sequences of PCR-amplified DNA from the flatfish species were used to select eight restriction enzymes (REs). The PCR products were cut with each RE, resulting in species-specific restriction fragment length polymorphism. Seven species groups could be identified by application of the single RE DdeI and six species groups by using HaeIII, HinfI, MaeI, or MboI. Different combinations of only a couple of these REs could unambiguously identify the nine flatfish species. Genetic polymorphisms of the target sequence were examined by comparison with previously published DNA sequences, and the results of this comparison confirmed the usefulness of this technique in distinguishing and genetically characterizing refrigerated or frozen pieces of these nine flatfish species.

  10. Identification of phytophthora isolates to species level using restriction fragment length polymorphism analysis of a polymerase chain reaction-amplified region of mitochondrial DNA.

    PubMed

    Martin, Frank N; Tooley, Paul W

    2004-09-01

    ABSTRACT Polymerase chain reaction primers spanning the mitochondrially encoded coxI and II genes have been identified that were capable of amplifying target DNA from all 152 isolates of 31 species in the genus Phytophthora that were tested. Digestion of the amplicons with restriction enzymes generated species-specific restriction fragment length polymorphism banding profiles that were effective for isolate classification to a species level. Of the 24 species in which multiple isolates were examined, intraspecific polymorphisms were not observed for 16 species, while 5 species exhibited limited intraspecific polymorphism that could be explained by the addition/loss of a single restriction site. Intraspecific polymorphisms were observed for P. megakarya, P. megasperma, and P. syringae; however, these differences may be a reflection of the variation that exists in these species as reported in the literature. Although digestion with AluI alone could differentiate most species tested, single digests with a total of four restriction enzymes were used in this investigation to enhance the accuracy of the technique and minimize the effect of intraspecific variability on correct isolate identification. The use of the computer program BioNumerics simplified data analysis and identification of isolates. Successful template amplification was obtained with DNA recovered from hyphae using a boiling miniprep procedure, thereby reducing the time and materials needed for conducting this analysis.

  11. The diazo route to diazonamide A. Studies on the indole bis-oxazole fragment.

    PubMed

    Davies, James R; Kane, Peter D; Moody, Christopher J

    2005-09-02

    [structure: see text] Various approaches to the indole bis-oxazole fragment of the marine secondary metabolite diazonamide A are described, all of which feature dirhodium(II)-catalyzed reactions of diazocarbonyl compounds in key steps. Thus, 3-bromophenylacetaldehyde is converted into an alpha-diazo-beta-ketoester, dirhodium(II)-catalyzed reaction of which with N-Boc-valinamide resulted in N-H insertion of the intermediate rhodium carbene to give a ketoamide that readily underwent cyclodehydration to give (S)-2-(1-tert-butoxycarbonylamino)-2-methylpropyl]-5-(3-bromobenzyl)oxazole-4-carboxamide, after ammonolysis of the initially formed ester. This aryl bromide was then coupled to a 3-formyl-indole-4-boronate under Pd catalysis to give the expected biaryl. Subsequent conversion of the aldehyde group into a second alpha-diazo-beta-ketoester gave a substrate for an intramolecular carbene N-H insertion, although attempts to effect this cyclization were unsuccessful. A second approach to an indole bis-oxazole involved an intermolecular rhodium carbene N-H insertion, followed by oxazole formation to give (S)-2-[1-tert-(butoxycarbonylamino)-2-methylpropyl]-5-methyloxazole-4-carboxamide. A further N-H insertion of this carboxmide with the rhodium carbene derived from ethyl 2-diazo-3-[1-(2-nitrobenzenesulfonyl)indol-3-yl]-3-oxopropanoate gave a ketoamide, cyclodehydration of which gave the desired indole bis-oxazole. Finally, the boronate formed from 4-bromotryptamine was coupled to another diazocarbonyl-derived oxazole to give the corresponding biaryl, deprotection and cyclization of which produced a macrocyclic indole-oxazole derivative. Subsequent oxidation and cyclodehydration incorporated the second oxazole and gave the macrocyclic indole bis-oxazole.

  12. Energetics and Dynamics of Fragmentation of Protonated Leucine Enkephalin from Time- and Energy-Resolved Surface-Induced Dissociation Studies

    SciTech Connect

    Laskin, Julia

    2006-07-01

    Dissociation of singly protonated leucine enkephalin (YGGFL) was studied using surface-induced dissociation in a Fourier transform ion cyclotron resonance mass spectrometer specially configured for studying ion activation by collisions with surfaces. The energetics and dynamics of seven primary dissociation channels were deduced from modeling the time- and energy-resolved fragmentation efficiency curves for different fragment ions using an RRKM-based approach developed at the Environmental Molecular Sciences Laboratory (EMSL).

  13. [Was Beethoven's deafness caused by Paget's disease? Report of findings and study of skull fragments of Ludwig van Beethoven].

    PubMed

    Jesserer, H; Bankl, H

    1986-10-01

    Paget's disease of bone (osteitis deformans) has been repeatedly named as a possible cause for Ludwig van Beethoven's deafness. In 1985 a descendent of Franz Romeo Seligmann (a Viennese medical historian who in 1863 had studied Beethoven's mortal remains on the occasion of their relocation) presented to us three bone fragments allegedly from Beethoven's cranium. They represented fragments of the left parietal bone and the occiputum. It was possible to prove nearly with certainty that these bone fragments actually are Beethoven's. They did not show signs of Paget's disease of bone. It must therefore be concluded that Beethoven's deafness was not caused by Paget's osteitis deformans.

  14. Experimental Study of Stellar Reactions at CNS

    SciTech Connect

    Kubono, S.; Yamaguchi, H.; Wakabayashi, Y.; Amadio, G.; Hayakawa, S.; He, J. J.; Saito, A.; Teranishi, T.; Nishimura, S.; Fukunishi, N.; Iwasa, N.; Inafuku, K.; Kato, S.; Tanaka, M. H.; Fuchi, Y.; Moon, J. Y.; Kwon, K.; Lee, C. S.; Khiem, Le Hong; Chen, A.

    2006-11-02

    After a brief review on low-energy RI beam production technology, nuclear astrophysics programs at CNS are presented including a scope of the field in the Wako campus. The CRIB project involves a total development of the whole facility to maximize the low-energy RI beam intensities, including the ion source, the AVF cyclotron and the low-energy RI beam separator CRIB, Some recent nuclear astrophysics experiments performed with the RI beams were discussed, including the measurement of the 14O({alpha},p)17F reaction, the key stellar reaction for the onset of the high-temperature rp-process. The first experiment performed with a newly installed high-resolution magnetic spectrograph PA of CNS was also presented. Collaboration possibilities for nuclear astrophysics in the RIKEN campus are also touched.

  15. Theoretical study of chemical reactions in solution

    SciTech Connect

    Yokogawa, D.

    2015-12-31

    Quantum chemical calculations in solution are becoming more and more important in chemistry. Reference interaction site model self-consistent field (RISM-SCF) is one of the powerful approaches to perform quantum chemical calculations in solution. In this work, we developed a new generation of RISM-SCF, where a robust fitting method was newly introduced. We applied the new method to tautomerization reaction of cytosine in aqueous phase. Our calculation reproduced experimentally obtained relative stabilities and relative free energies correctly.

  16. Detailed studies of survival probabilities in hot fusion reactions

    NASA Astrophysics Data System (ADS)

    Yao, Liangyu; Yanez, Ricardo; Loveland, Walter

    2011-10-01

    In the synthesis of new heavy nuclei by hot fusion reactions, the cross section for producing a new heavy nucleus, σEVR, can be represented as σEVR(EC.M.)=&Jmaxcirc;J=0σCN(Ec.m.,J) .Wsur(Ec.m.,J) where σCN is the complete fusion cross section and Wsur is the survival probability of the completely fused system. The survival probability is essentially the probability of de-exciting by neutron emission instead of fission. In this work, we are attempting to measure the survival probability, Wsur, for the first chance fission of excited Hs nuclei. We form the Hs nuclei using the ^25,26Mg + ^248Cm reaction. We measure the neutrons associated with pre-fission emission and those emitted by the fission fragments after fission using six BC501 neutron detectors and six silicon fission fragment detectors. We measure the angular distribution of the emitted neutrons and are able to separate the pre- and post-fission neutrons.

  17. Integrating edge effects into studies of habitat fragmentation: a test using meiofauna in seagrass.

    PubMed

    Warry, F Y; Hindell, J S; Macreadie, P I; Jenkins, G P; Connolly, R M

    2009-04-01

    Habitat fragmentation is thought to be an important process structuring landscapes in marine and estuarine environments, but effects on fauna are poorly understood, in part because of a focus on patchiness rather than fragmentation. Furthermore, despite concomitant increases in perimeter:area ratios with fragmentation, we have little understanding of how fauna change from patch edges to interiors during fragmentation. Densities of meiofauna were measured at different distances across the edges of four artificial seagrass treatments [continuous, fragmented, procedural control (to control for disturbance by fragmenting then restoring experimental plots), and patchy] 1 day, 1 week and 1 month after fragmentation. Experimental plots were established 1 week prior to fragmentation/disturbance. Samples were numerically dominated by harpacticoid copepods, densities of which were greater at the edge than 0.5 m into patches for continuous, procedural control and patchy treatments; densities were similar between the edge and 0.5 m in fragmented patches. For taxa that demonstrated edge effects, densities exhibited log-linear declines to 0.5 m into a patch with no differences observed between 0.5 m and 1 m into continuous treatments. In patchy treatments densities were similar at the internal and external edges for many taxa. The strong positive edge effect (higher densities at edge than interior) for taxa such as harpacticoid copepods implies some benefit of patchy landscapes. But the lack of edge effects during patch fragmentation itself demonstrates the importance of the mechanisms by which habitats become patchy.

  18. Development of Diagnostic Fragment Ion Library for Glycated Peptides of Human Serum Albumin: Targeted Quantification in Prediabetic, Diabetic, and Microalbuminuria Plasma by Parallel Reaction Monitoring, SWATH, and MSE*

    PubMed Central

    Korwar, Arvind M.; Vannuruswamy, Garikapati; Jagadeeshaprasad, Mashanipalya G.; Jayaramaiah, Ramesha H.; Bhat, Shweta; Regin, Bhaskaran S.; Ramaswamy, Sureshkumar; Giri, Ashok P.; Mohan, Viswanathan; Balasubramanyam, Muthuswamy; Kulkarni, Mahesh J.

    2015-01-01

    Human serum albumin is one of the most abundant plasma proteins that readily undergoes glycation, thus glycated albumin has been suggested as an additional marker for monitoring glycemic status. Hitherto, only Amadori-modified peptides of albumin were quantified. In this study, we report the construction of fragment ion library for Amadori-modified lysine (AML), N(ε)-(carboxymethyl)lysine (CML)-, and N(ε)-(carboxyethyl)lysine (CEL)-modified peptides of the corresponding synthetically modified albumin using high resolution accurate mass spectrometry (HR/AM). The glycated peptides were manually inspected and validated for their modification. Further, the fragment ion library was used for quantification of glycated peptides of albumin in the context of diabetes. Targeted Sequential Window Acquisition of all THeoretical Mass Spectra (SWATH) analysis in pooled plasma samples of control, prediabetes, diabetes, and microalbuminuria, has led to identification and quantification of 13 glycated peptides comprised of four AML, seven CML, and two CEL modifications, representing nine lysine sites of albumin. Five lysine sites namely K549, K438, K490, K88, and K375, were observed to be highly sensitive for glycation modification as their respective m/z showed maximum fold change and had both AML and CML modifications. Thus, peptides involving these lysine sites could be potential novel markers to assess the degree of glycation in diabetes. PMID:26023067

  19. Development of Diagnostic Fragment Ion Library for Glycated Peptides of Human Serum Albumin: Targeted Quantification in Prediabetic, Diabetic, and Microalbuminuria Plasma by Parallel Reaction Monitoring, SWATH, and MSE.

    PubMed

    Korwar, Arvind M; Vannuruswamy, Garikapati; Jagadeeshaprasad, Mashanipalya G; Jayaramaiah, Ramesha H; Bhat, Shweta; Regin, Bhaskaran S; Ramaswamy, Sureshkumar; Giri, Ashok P; Mohan, Viswanathan; Balasubramanyam, Muthuswamy; Kulkarni, Mahesh J

    2015-08-01

    Human serum albumin is one of the most abundant plasma proteins that readily undergoes glycation, thus glycated albumin has been suggested as an additional marker for monitoring glycemic status. Hitherto, only Amadori-modified peptides of albumin were quantified. In this study, we report the construction of fragment ion library for Amadori-modified lysine (AML), N(ε)-(carboxymethyl)lysine (CML)-, and N(ε)-(carboxyethyl)lysine (CEL)-modified peptides of the corresponding synthetically modified albumin using high resolution accurate mass spectrometry (HR/AM). The glycated peptides were manually inspected and validated for their modification. Further, the fragment ion library was used for quantification of glycated peptides of albumin in the context of diabetes. Targeted Sequential Window Acquisition of all THeoretical Mass Spectra (SWATH) analysis in pooled plasma samples of control, prediabetes, diabetes, and microalbuminuria, has led to identification and quantification of 13 glycated peptides comprised of four AML, seven CML, and two CEL modifications, representing nine lysine sites of albumin. Five lysine sites namely K549, K438, K490, K88, and K375, were observed to be highly sensitive for glycation modification as their respective m/z showed maximum fold change and had both AML and CML modifications. Thus, peptides involving these lysine sites could be potential novel markers to assess the degree of glycation in diabetes. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. Pharmacologic study of C-terminal fragments of frog skin calcitonin gene-related peptide.

    PubMed

    Ladram, Ali; Besné, Isabelle; Breton, Lionel; de Lacharrière, Olivier; Nicolas, Pierre; Amiche, Mohamed

    2008-07-01

    The calcitonin gene-related peptide from the skin of the frog Phyllomedusa bicolor (pbCGRP) is a 37-residue neuropeptide that differs from human alpha CGRP (halphaCGRP) at 16 positions. The affinities of the C-terminal fragments of pbCGRP and halphaCGRP were evaluated in SK-N-MC cells: pbCGRP(8-37) (K(i)=0.2nM) and pbCGRP(27-37) (K(i)=95nM) were, respectively, 3 times and 20 times more potent than the human fragments halphaCGRP(8-37) and halphaCGRP(27-37). Their antagonistic potencies were measured in SK-N-MC and Col 29 cells, and the rat vas deferens. pbCGRP(8-37) inhibited the halphaCGRP-stimulated production of cAMP by SK-N-MC and Col 29 cells 3 to 4 times more strongly than halphaCGRP(8-37). Thus pbCGRP(8-37) is the most potent CGRP-1 competitive antagonist of all the natural sequences reported to date. pbCGRP(27-37) was also as potent as [D(31), A(34), F(35)] halphaCGRP(27-37), a prototypic antagonist analog derived from structure-activity relationship studies of halphaCGRP(8-37).

  1. A Holistic Multi Evidence Approach to Study the Fragmentation Behaviour of Crystalline Mannitol

    NASA Astrophysics Data System (ADS)

    Koner, Jasdip S.; Rajabi-Siahboomi, Ali; Bowen, James; Perrie, Yvonne; Kirby, Daniel; Mohammed, Afzal R.

    2015-11-01

    Mannitol is an essential excipient employed in orally disintegrating tablets due to its high palatability. However its fundamental disadvantage is its fragmentation during direct compression, producing mechanically weak tablets. The primary aim of this study was to assess the fracture behaviour of crystalline mannitol in relation to the energy input during direct compression, utilising ball milling as the method of energy input, whilst assessing tablet characteristics of post-milled powders. Results indicated that crystalline mannitol fractured at the hydrophilic (011) plane, as observed through SEM, alongside a reduction in dispersive surface energy. Disintegration times of post-milled tablets were reduced due to the exposure of the hydrophilic plane, whilst more robust tablets were produced. This was shown through higher tablet hardness and increased plastic deformation profiles of the post-milled powders, as observed with a lower yield pressure through an out-of-die Heckel analysis. Evaluation of crystal state using x-ray diffraction/differential scanning calorimetry showed that mannitol predominantly retained the β-polymorph however x-ray diffraction provided a novel method to calculate energy input into the powders during ball milling. It can be concluded that particle size reduction is a pragmatic strategy to overcome the current limitation of mannitol fragmentation and provide improvements in tablet properties.

  2. Human semen cryopreservation: a sperm DNA fragmentation study with alkaline and neutral Comet assay.

    PubMed

    Ribas-Maynou, J; Fernández-Encinas, A; García-Peiró, A; Prada, E; Abad, C; Amengual, M J; Navarro, J; Benet, J

    2014-01-01

    Sperm cryopreservation is widely used for both research and reproduction purposes, but its effect on sperm DNA damage remains controversial. Sperm DNA fragmentation (SDF) has become an important biomarker to assess male infertility. In particular, the differentiation between single- and double-stranded DNA fragmentation (ssSDF and dsSDF) has clinical implications for male infertility where ssSDF is associated with reduced fertility, whereas dsSDF is associated with increased risk of miscarriage. In this study, semen samples from 30 human males have been analysed in both fresh and cryopreserved using the alkaline and neutral Comet assays. Results show an increase of about 10% of ssSDF, assessed by the alkaline Comet assay, regardless of the male fertility status. Neutral Comet analysis of dsSDF does not show any statistical increase when comparing fresh and cryopreserved samples in any of the patient groups. Results support previous reports that oxidative stress is the major effector in DNA damage during sample cryopreservation, as, on one hand, ssSDF has previously been related to oxidative damage and, on the other hand, we have not found any effect on dsSDF. Therefore, there might be a slight risk of decreased fertility after using a freezed sample, but no evidence for increased miscarriage risk from cryopreserved spermatozoa should be expected. © 2013 American Society of Andrology and European Academy of Andrology.

  3. A Holistic Multi Evidence Approach to Study the Fragmentation Behaviour of Crystalline Mannitol

    PubMed Central

    Koner, Jasdip S.; Rajabi-Siahboomi, Ali; Bowen, James; Perrie, Yvonne; Kirby, Daniel; Mohammed, Afzal R.

    2015-01-01

    Mannitol is an essential excipient employed in orally disintegrating tablets due to its high palatability. However its fundamental disadvantage is its fragmentation during direct compression, producing mechanically weak tablets. The primary aim of this study was to assess the fracture behaviour of crystalline mannitol in relation to the energy input during direct compression, utilising ball milling as the method of energy input, whilst assessing tablet characteristics of post-milled powders. Results indicated that crystalline mannitol fractured at the hydrophilic (011) plane, as observed through SEM, alongside a reduction in dispersive surface energy. Disintegration times of post-milled tablets were reduced due to the exposure of the hydrophilic plane, whilst more robust tablets were produced. This was shown through higher tablet hardness and increased plastic deformation profiles of the post-milled powders, as observed with a lower yield pressure through an out-of-die Heckel analysis. Evaluation of crystal state using x-ray diffraction/differential scanning calorimetry showed that mannitol predominantly retained the β-polymorph; however x-ray diffraction provided a novel method to calculate energy input into the powders during ball milling. It can be concluded that particle size reduction is a pragmatic strategy to overcome the current limitation of mannitol fragmentation and provide improvements in tablet properties. PMID:26553127

  4. The effect of habitat fragmentation on cyclic population dynamics: a numerical study.

    PubMed

    Strohm, S; Tyson, R

    2009-08-01

    Through four spatially explicit models, we investigate how habitat fragmentation affects cyclic predator-prey population dynamics. We use a Partial Differential Equation (PDE) framework to describe the dispersal of predators and prey in a heterogeneous landscape made of high quality and low quality habitat patches, subject to increasing fragmentation through habitat separation and/or habitat loss. Our results show that habitat fragmentation decreases the amplitude of the predator-prey population cycles while average population density is not as strongly affected in general. Beyond these simple trends however, the four models show differing responses to fragmentation, indicating that when making predictions about population survival and persistence in the face of habitat fragmentation, the choice of model is important. Our results may inform conservation efforts in fragmented habitats for cyclic species such as the snowshoe hare and Canada lynx.

  5. Studies on Pyridazine Azide Cyclisation Reactions

    SciTech Connect

    Allan, R.D.; Greenwood, J.; Hambley, T.; Hanrahan, J.R.; Hibbs, D.E.; Itani, S.; Tran, H.; Turner, P.

    2010-11-16

    Reaction of sodium azide with 4-methyl-3,5,6-tribromopyridazine results in the formation of 3,5,6-triazide intermediate which could cyclise to give two possible bicyclic products while ab initio calculations show that the formation of a tricyclic compound is extremely energetically unfavourable. However, experimentally, only one major product is isolated. The structure of this unstable product has been conclusively established by X-ray crystallography as 3,5-diazido-4-methyl[1,5-b]tetrazolopyridazine confirming theoretical predictions.

  6. Fragmented Adipose Tissue Graft for Bone Healing: Histological and Histometric Study in Rabbits’ Calvaria

    PubMed Central

    Oliveira, Lidiane C.; Giovanini, Allan F.; Abuabara, Allan; Klug, Luiz G.; Gonzaga, Carla C.; Zielak, João C.; Urban, Cícero A.

    2013-01-01

    Objective The adipose tissue represents an important reservoir of stem cells. There are few studies in the literature with which to histologically evaluate whether or not the adipose tissue graft is really a safe option to achieve bone repair. This study histologically analyzed the effect of fragmented autogenous adipose tissue grafts on bone healing in surgically created, critical-size defects (CSD) in a rabbit’s calvaria. Study design Forty-two New Zealand rabbits were used in this study. CSD that were 15 mm in diameter were created in the calvarium of each animal. The defects were randomly divided into two groups: in Group C (control), the defect was filled only by a blood clot and, in Group FAT (i.e., fragmented adipose tissue), the defect was filled with fragmented autogenous adipose tissue grafts. The groups were divided into subgroups (n = 7) for euthanasia at 7, 15, and 40 days after the procedure had been conducted. Histologic and histometric analyses were performed. Data were statistically analysed with ANOVA and Tukey’s tests (p < 0.05). Results The amount of bone formation did not show statistically significant differences seven days after the operation, which indicates that the groups had similar amounts of mineral deposition in the earlier period of the repair. Conversely, a significant of amount of bone matrix deposition was identified in the FAT group at 15 and 40 days following the operation, both on the border and in the body of the defect. Such an outcome was not found in the control group. Conclusion In this study, an autologous adipose tissue graft may be considered as likely biomaterial for bone regeneration, since it positively affected the amount of bone formation in surgically created CSD in the rabbits’ calvaria 40 days after the procedure had been performed. Further investigations with a longer time evaluation are warranted to determine the effectiveness of autologous adipose tissue graft in the bone healing. Key words

  7. Study of apoptosis in skin lesions of leprosy in relation to treatment and lepra reactions.

    PubMed

    Ajith, C; Gupta, Sachin; Radotra, Bishan D; Arora, Sunil K; Kumar, Bhushan; Dogra, Sunil; Kaur, Inderjeet

    2005-12-01

    In leprosy on treatment, one factor contributing to the healing of skin lesions with minimal fibrosis may be apoptosis of inflammatory cells, even though apoptosis is sparse in leprosy as compared to tuberculosis. The degree of apoptosis in skin lesions of leprosy was studied by histopathologic examination (HPE) and by DNA fragmentation and electrophoresis. The effect of various parameters on apoptosis was noted in untreated disease, during treatment at 3 and 6 months, and in lepra reactions in different parts of the spectrum of leprosy. Of the 31 patients, 13 had paucibacillary (PB) and 18 multibacillary (MB) disease. Twenty one patients were in reaction: 16 had type 1 reaction and 5 had type 2 reaction. The controls included patients with non-granulomatous skin diseases; there were no normal controls, and no separate controls for cases with reaction. Apoptosis occurred more frequently in patients with leprosy as compared to the controls. In both PB & MB lesions, apoptosis was observed to increase progressively with treatment at 3 and 6 months, and was more prominent in the MB cases at 6 months of treatment. When lesions in either type 1 or type 2 reaction were compared to lesions not in reaction, a significant increase in apoptosis (p = 0.014) was found only in lesions with type 2 reaction and those which were at 6 months of treatment. The type of treatment regimen, or oral steroids given for reactions, did not significantly alter the degree of apoptosis. Our observations indicate that increased apoptosis is present in leprosy lesions and that in leprosy it progressively increases with anti-leprosy treatment up to 6 months. If the process of apoptosis in skin lesions is followed up for a longer period of time, the degree of apoptosis may be expected to decline. The study of apoptosis may help to understand the mechanism of clearance of bacilli and resolution of granulomas in leprosy patients.

  8. Oxygen radical-mediated oxidation reactions of an alanine peptide motif - density functional theory and transition state theory study.

    PubMed

    Chen, Hsing-Yu; Jang, Soonmin; Jinn, Tzyy-Rong; Chang, Jia-Yaw; Lu, Hsiu-Feng; Li, Feng-Yin

    2012-04-24

    Oxygen-base (O-base) oxidation in protein backbone is important in the protein backbone fragmentation due to the attack from reactive oxygen species (ROS). In this study, an alanine peptide was used model system to investigate this O-base oxidation by employing density functional theory (DFT) calculations combining with continuum solvent model. Detailed reaction steps were analyzed along with their reaction rate constants. Most of the O-base oxidation reactions for this alanine peptide are exothermic except for the bond-breakage of the Cα-N bond to form hydroperoxy alanine radical. Among the reactions investigated in this study, the activated energy of OH α-H abstraction is the lowest one, while the generation of alkylperoxy peptide radical must overcome the highest energy barrier. The aqueous situation facilitates the oxidation reactions to generate hydroxyl alanine peptide derivatives except for the fragmentations of alkoxyl alanine peptide radical. The Cα-Cβ bond of the alkoxyl alanine peptide radical is more labile than the peptide bond. the rate-determining step of oxidation in protein backbone is the generation of hydroperoxy peptide radical via the reaction of alkylperoxy peptide radical with HO2. The stabilities of alkylperoxy peptide radical and complex of alkylperoxy peptide radical with HO2 are crucial in this O-base oxidation reaction.

  9. Oxygen radical-mediated oxidation reactions of an alanine peptide motif - density functional theory and transition state theory study

    PubMed Central

    2012-01-01

    Background Oxygen-base (O-base) oxidation in protein backbone is important in the protein backbone fragmentation due to the attack from reactive oxygen species (ROS). In this study, an alanine peptide was used model system to investigate this O-base oxidation by employing density functional theory (DFT) calculations combining with continuum solvent model. Detailed reaction steps were analyzed along with their reaction rate constants. Results Most of the O-base oxidation reactions for this alanine peptide are exothermic except for the bond-breakage of the Cα-N bond to form hydroperoxy alanine radical. Among the reactions investigated in this study, the activated energy of OH α-H abstraction is the lowest one, while the generation of alkylperoxy peptide radical must overcome the highest energy barrier. The aqueous situation facilitates the oxidation reactions to generate hydroxyl alanine peptide derivatives except for the fragmentations of alkoxyl alanine peptide radical. The Cα-Cβ bond of the alkoxyl alanine peptide radical is more labile than the peptide bond. Conclusion the rate-determining step of oxidation in protein backbone is the generation of hydroperoxy peptide radical via the reaction of alkylperoxy peptide radical with HO2. The stabilities of alkylperoxy peptide radical and complex of alkylperoxy peptide radical with HO2 are crucial in this O-base oxidation reaction. PMID:22524792

  10. Neutron-induced reaction studies using stored ions

    NASA Astrophysics Data System (ADS)

    Glorius, Jan; Litvinov, Yuri A.; Reifarth, René

    2015-11-01

    Storage rings provide unique possibilities for investigations of nuclear reactions. Radioactive ions can be stored if the ring is connected to an appropriate facility and reaction studies are feasible at low beam intensities because of the recycling of beam particles. Using gas jet or droplet targets, charged particle-induced reactions on short-lived isotopes can be studied in inverse kinematics. In such a system a high-flux reactor could serve as a neutron target extending the experimental spectrum to neutron-induced reactions. Those could be studied over a wide energy range covering the research fields of nuclear astrophysics and reactor safety, transmutation of nuclear waste and fusion.

  11. A theoretical and mass spectrometry study of the fragmentation of mycosporine-like amino acids

    NASA Astrophysics Data System (ADS)

    Cardozo, Karina H. M.; Vessecchi, Ricardo; Carvalho, Valdemir M.; Pinto, Ernani; Gates, Paul J.; Colepicolo, Pio; Galembeck, Sérgio E.; Lopes, Norberto P.

    2008-06-01

    In the present study, the mycosporine-like amino acids (MAAs) were isolated from the marine red alga Gracilaria tenuistipitata and analysed by high-resolution accurate-mass sequential mass spectrometry (MSn). In addition to the proposed fragmentation mechanism based on the MSn analysis, it is clearly demonstrated that the elimination of mass 15 is a radical processes taking place at the methoxyl substituent of the double bond. This characteristic loss of a methyl radical was studied by theoretical calculations and the homolytic cleavage of the OC bond is suggested to be dependent on the bond weakening. The protonation site of the MAAs was indicated by analysis of the Fukui functions and the relative Gibbs energies of the several possible protonated forms.

  12. COLLISIONS OF POROUS CLUSTERS: A GRANULAR-MECHANICS STUDY OF COMPACTION AND FRAGMENTATION

    SciTech Connect

    Ringl, Christian; Urbassek, Herbert M.; Bringa, Eduardo M.; Bertoldi, Dalia S.

    2012-06-20

    The collision of granular clusters can result in a number of complex outcomes from sticking to partial or full destruction of the clusters. These outcomes will contribute to the size distribution of dust aggregates, changing their optical properties and their capability to contribute to solid-state astrochemistry. We study the collision of two clusters of equal size, formed by approximately 7000 sub-{mu}m grains each, with a mass and velocity range that is difficult to sample in experiments. We obtain the outcome of the collision: compaction, fragmentation, and size distribution of ejecta, and type of outcome, as a function of velocity and impact parameter. We compare our results to other models and simulations, at both atomistic and continuum scales, and find some agreement together with some discrepancies. We also study collision-induced compaction as a function of cluster size, up to sizes of N = 250, 000, and find that for large clusters considerably higher compactions result at higher velocities.

  13. Characterization and development of an active scintillating target for nuclear reaction studies on actinides

    NASA Astrophysics Data System (ADS)

    Belier, Gilbert; Aupiais, Jean; Varignon, Cyril; Vayre, Sylvain

    2012-02-01

    This article presents the development of a new kind of active actinide target, based on organic liquid scintillators containing the dissolved isotope. Amongst many advantages one can mention the very high detection efficiency, the Pulse Shape Discrimination capability, the fast response allowing high count rates and good time resolution and the ease of fabrication. The response of this target to fission fragments has been studied. The discrimination of alpha, fission and proton recoil events is demonstrated. The alpha decay and fission detection efficiencies are simulated and compared to measurements. Finally the use of such a target in the context of fast neutron induced reactions is discussed.

  14. Culture, Polymerase Chain Reaction and Restriction Fragment Length Polymorphism Studies in Bartonella bacilliformis

    DTIC Science & Technology

    1998-09-22

    agarose gel. The Bgi I digestions of the plasmid suggested that the pBS was somehow altered , and that it had lost RE sites. It was decided that the stock...of pBS that had been used for all ligations up to this point was altered and therefore not performing as expected. This stock of pBS was discarded, and...they were either absent or altered in the insert DNA of B. bacilli/ormis, KC583. It is also interesting to note that primer set 1 produced specific

  15. [Reaction mechanism studies of heavy ion induced nuclear reactions]. Annual progress report, [January 1992--February 1993

    SciTech Connect

    Mignerey, A.C.

    1993-02-01

    Completed work is summarized on the topics of excitation energy division in deep-inelastic reactions and the onset of multifragmentation in La-induced reactions at E/A = 45 MeV. Magnetic fields are being calculated for the PHOBOS detector system, a two-arm multiparticle spectrometer for studying low-transverse-momentum particles produced at the Relativistic Heavy Ion Collider. The Maryland Forward Array is being developed for detection of the reaction products from very peripheral collisions; it consists of two individual units of detectors: the annular silicon detector in front and the plastic phoswich detector at back.

  16. Computational study of silica-supported transition metal fragments for Kubas-type hydrogen storage.

    PubMed

    Skipper, Claire V J; Hamaed, Ahmad; Antonelli, David M; Kaltsoyannis, Nikolas

    2010-12-08

    To verify the role of the Kubas interaction in transition metal grafted mesoporous silicas, and to rationalize unusual rising enthalpy trends with surface coverage by hydrogen in these systems, computational studies have been performed. Thus, the interaction of H2 with the titanium centers in molecular models for experimentally characterized mesoporous silica-based H2 absorption materials has been studied quantum chemically using gradient corrected density functional theory. The interaction between the titanium and the H2 molecules is found to be of a synergic, Kubas type, and a maximum of four H2 molecules can be bound to each titanium, in good agreement with previous experiments. The average Ti-H2 interaction energies in molecules incorporating benzyl ancillary ligands (models of the experimental systems) increase as the number of bound H2 units increases from two to four, in agreement with the experimental observation that the H2 adsorption enthalpy increases as the number of adsorbed H2 molecules increases. The Ti-H2 interaction is shown to be greater when the titanium is bound to ancillary ligands, which are poor π-acceptors, and when the ancillary ligand causes the least steric hindrance to the metal. Extension of the target systems to vanadium and chromium shows that, for molecules containing hydride ancillary ligands, a good relationship is found between the energies of the frontier molecular orbitals of the molecular fragments, which interact with incoming H2 molecules, and the strength of the M-H2 interaction. For the benzyl systems, both the differences in M-H2 interaction energies and the energy differences in frontier orbital energies are smaller than those in the hydrides, such that conclusions based on frontier orbital energies are less robust than for the hydride systems. Because of the high enthalpies predicted for organometallic fragments containing hydride ligands, and the low affinity of Cr(III) for hydrogen in this study, these features may

  17. C-H bond activation of methane in aqueous solution: a hybrid quantum mechanical/effective fragment potential study.

    PubMed

    Da Silva, Júlio C S; Rocha, Willian R

    2011-12-01

    In this study, we investigated the C-H bond activation of methane catalyzed by the complex [PtCl(4)](2-), using the hybrid quantum mechanical/effective fragment potential (EFP) approach. We analyzed the structures, energetic properties, and reaction mechanism involved in the elementary steps that compose the catalytic cycle of the Shilov reaction. Our B3LYP/SBKJC/cc-pVDZ/EFP results show that the methane activation may proceed through two pathways: (i) electrophilic addition or (ii) direct oxidative addition of the C-H bond of the alkane. The electrophilic addition pathway proceeds in two steps with formation of a σ-methane complex, with a Gibbs free energy barrier of 24.6 kcal mol(-1), followed by the cleavage of the C-H bond, with an energy barrier of 4.3 kcal mol(-1) . The activation Gibbs free energy, calculated for the methane uptake step was 24.6 kcal mol(-1), which is in good agreement with experimental value of 23.1 kcal mol(-1) obtained for a related system. The results shows that the activation of the C-H bond promoted by the [PtCl(4)](2-) catalyst in aqueous solution occurs through a direct oxidative addition of the C-H bond, in a single step, with an activation free energy of 25.2 kcal mol(-1), as the electrophilic addition pathway leads to the formation of a σ-methane intermediate that rapidly undergoes decomposition. The inclusion of long-range solvent effects with polarizable continuum model does not change the activation energies computed at the B3LYP/SBKJC/cc-pVDZ/EFP level of theory significantly, indicating that the large EFP water cluster used, obtained from Monte Carlo simulations and analysis of the center-of-mass radial pair distribution function, captures the most important solvent effects.

  18. NASTRAN buckling study of a linear induction motor reaction rail

    NASA Technical Reports Server (NTRS)

    Williams, J. G.

    1973-01-01

    NASTRAN was used to study problems associated with the installation of a linear induction motor reaction rail test track. Specific problems studied include determination of the critical axial compressive buckling stress and establishment of the lateral stiffness of the reaction rail under combined loads. NASTRAN results were compared with experimentally obtained values and satisfactory agreement was obtained. The reaction rail was found to buckle at an axial compressive stress of 11,400 pounds per square inch. The results of this investigation were used to select procedures for installation of the reaction rail.

  19. Multiple reaction monitoring with multistage fragmentation (MRM3) detection enhances selectivity for LC-MS/MS analysis of plasma free metanephrines.

    PubMed

    Wright, Michael J; Thomas, Rebecca L; Stanford, Phoebe E; Horvath, Andrea R

    2015-03-01

    LC-MS/MS with multiple reaction monitoring (MRM) is a powerful tool for quantifying target analytes in complex matrices. However, the technique lacks selectivity when plasma free metanephrines are measured. We propose the use of multistage fragmentation (MRM(3)) to improve the analytical selectivity of plasma free metanephrine measurement. Metanephrines were extracted from plasma with weak cation exchange solid-phase extraction before separation by hydrophilic interaction liquid chromatography. We quantified normetanephrine and metanephrine by either MRM or MRM(3) transitions m/z 166→134→79 and m/z 180→149→121, respectively. Over a 6-month period, approximately 1% (n = 21) of patient samples showed uncharacterized coeluting substances that interfered with the routine assay, resulting in an inability to report results. Quantification with MRM(3) removed these interferences and enabled measurement of the target compounds. For patient samples unaffected by interferences, Deming regression analysis demonstrated a correlation between MRM(3) and MRM methods of y = 1.00x - 0.00 nmol/L for normetanephrine and y = 0.99x + 0.03 nmol/L for metanephrine. Between the MRM(3) method and the median of all LC-MS/MS laboratories enrolled in a quality assurance program, the correlations were y = 0.97x + 0.03 nmol/L for normetanephrine and y = 1.03x - 0.04 nmol/L for metanephrine. Imprecision for the MRM(3) method was 6.2%-7.0% for normetanephrine and 6.1%-9.9% for metanephrine (n = 10). The lower limits of quantification for the MRM(3) method were 0.20 nmol/L for normetanephrine and 0.16 nmol/L for metanephrine. The use of MRM(3) technology improves the analytical selectivity of plasma free metanephrine quantification by LC-MS/MS while demonstrating sufficient analytical sensitivity and imprecision. © 2014 American Association for Clinical Chemistry.

  20. APPLICATION OF POLYMERASE CHAIN REACTION (PCR) AND PCR BASED RESTRICTION FRAGMENT LENGTH POLYMORPHISM FOR DETECTION AND IDENTIFICATION OF DERMATOPHYTES FROM DERMATOLOGICAL SPECIMENS

    PubMed Central

    Bagyalakshmi, R; Senthilvelan, B; Therese, K L; Murugusundram, S; Madhavan, H N

    2008-01-01

    Objective: To develop and optimize polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) targeting 18S rDNA and internal transcribed spacer (ITS) region of fungi for rapid detection and identification of dermatophytes. Materials and Methods: Two PCR-RFLP methods targeting 18S rDNA and ITS regions of fungi were optimized using standard and laboratory isolates of dermatophytes and other fungi. Sixty-eight dermatological clinical specimens (nail clippings (56), material obtained from blisters (8), hair root (2), scraping from scaly plaque of foot (1) and skin scraping (1) collected by the dermatologist were subjected to both the optimized PCR-RFLP and conventional mycological (smear and culture) methods. Results: PCRs targeting 18S rDNA and the ITS region were sensitive to detect 10 picograms and 1 femtogram of T. rubrum DNA, respectively. PCR targeting 18S rDNA was specific for dermatophytes and subsequent RFLP identified them to species level. PCR-RFLP targeting the ITS region differentiated dermatophytes from other fungi with identification to species level. Among the 68 clinical specimens tested, both PCR-RFLP methods revealed the presence of dermatophytes in 27 cases (39.7%), whereas culture revealed the same only in 2 cases (7.40%), increasing the clinical sensitivity by 32.3%. Among 20 smear positive specimens, both PCR-RFLP methods detected dermatophytes in 12 (17.6%). Both the methods detected the presence of dermatophytes in 13 (19.11%) smear and culture negative specimens, increasing the clinical sensitivity by 36.1%. Conclusion: PCR-RFLP methods targeting 18S rDNA and the ITS regions of fungi were specific and highly sensitive for detection and speciation of dermatophytes. PMID:19967012

  1. Multichannel study on the fragmentation of the 1g9/2 isobaric analog resonance in 53Mn

    NASA Astrophysics Data System (ADS)

    Sziklai, J.; Cameron, J. A.; Szöghy, I. M.; Vass, T.

    1994-02-01

    Fragments of the 1g9/2 isobaric analog resonance in 53Mn corresponding to the 3.715 MeV state (Sn=0.57) in 53Cr were located using the 52Cr(p,p0), 52Cr(p,p1), 52Cr(p,p1γ), 52Cr(p,p2γ), and 52Cr(p,γ)53Mn reactions. Differential cross sections were measured in the 4.06-4.28 MeV, and the γ-excitation curves in the 4.04-4.35 MeV proton energy region. Spins, parities, and partial widths were determined with the aid of R-matrix analysis for all resonances observed in the region. The spins of the 1g9/2 resonance fragments were found independently from (p,p1γ), (p,p2γ), and (p,γ) angular distribution measurements and their analyses. Nineteen fragments were identified and their γ-branching ratios to low lying levels of 53Mn were also deduced. Partial widths for each fragment in all four channels were derived. Channel-channel correlations were calculated. Fine structure analyses were carried out in all open channels. Inelastic spectroscopic factors and Coulomb displacement energy for the 1g9/2 state were also derived.

  2. Experimental and numerical study of thin fragments protection for radiographic detectors

    NASA Astrophysics Data System (ADS)

    Counilh, D.; Gillot, F.; Adolf, L.-M.; Silvin, P.; Rambert, N.; Hebert, D.; Bertron, I.; Bozier, O.

    2017-01-01

    To perform a non-intrusive measurement on a pyrotechnic setup, we usually use radiography. But, the X-ray generator and the detectors of the radiographic chain must be protected against the blast and. We carried out an experimental campaign to test the performances of various shielding. Representative cylindrical projectiles with various masses (from 20g to 40g) and aspect ratios (length to diameter ratio from 0.1 to 1) were launched with a gas gun at different initial velocities (from 1500m/s up to 2000m/s). Multiple shield configurations, based on assemblies of steel, aluminum and B4C plates were tested. The experimental results were combined with numerical studies to demonstrate the capabilities of the shield to stop fragments.

  3. Fragmentation dynamics of ionized neon trimer inside helium nanodroplets: a theoretical study.

    PubMed

    Bonhommeau, David; Viel, Alexandra; Halberstadt, Nadine

    2004-06-22

    We report a theoretical study of the fragmentation dynamics of Ne(3) (+) inside helium nanodroplets, following vertical ionization of the neutral neon trimer. The motion of the neon atoms is treated classically, while transitions between the electronic states of the ionic cluster are treated quantum mechanically. A diatomics-in-molecules description of the potential energy surfaces is used, in a minimal basis set consisting of three effective p orbitals on each neon atom for the missing electron. The helium environment is modeled by a friction force acting on the neon atoms when their speed exceeds the Landau velocity. A reasonable range of values for the corresponding friction coefficient is obtained by comparison with existing experimental measurements.

  4. Northeastern Regional Forest Fragmentation Assessment: Rationale, Methods, and Comparisons With Other Studies

    Treesearch

    Andrew Lister; Rachel Riemann; Tonya Lister; Will McWilliams

    2005-01-01

    Forest fragmentation is thought to impact many biotic and abiotic processes important to ecosystem function. We assessed forest fragmentation in 13 Northeastern States to gain a greater understanding of the trends in and status of this region?s forests. We reclassified and then statistically filtered and updated classified Landsat imagery from the early 1990s, and...

  5. Multitemporal analysis of forest fragmentation in Hindu Kush Himalaya-a case study from Khangchendzonga Biosphere Reserve, Sikkim, India.

    PubMed

    Sharma, Mohit; Areendran, G; Raj, Krishna; Sharma, Ankita; Joshi, P K

    2016-10-01

    Forests in the mountains are a treasure trove; harbour a large biodiversity; and provide fodder, firewood, timber and non-timber forest products; all of these are essential for human survival in the highest mountains on earth. The present paper attempts a spatiotemporal assessment of forest fragmentation and changes in land use land cover (LULC) pattern using multitemporal satellite data over a time span of around a decade (2000-2009), within the third highest protected area (PA) in the world. The fragmentation analysis using Landscape Fragmentation Tool (LFT) depicts a decrease in large core, edge and patches areas by 5.93, 3.64 and 0.66 %, respectively, while an increase in non-forest and perforated areas by 6.59 and 4.01 %, respectively. The land cover dynamics shows a decrease in open forest, alpine scrub, alpine meadows, snow and hill shadow areas by 2.81, 0.39, 8.18, 3.46 and 0.60 %, respectively, and there is an increase in dense forest and glacier area by 4.79 and 10.65 %, respectively. The change analysis shows a major transformation in areas from open forest to dense forest and from alpine meadows to alpine scrub. In order to quantify changes induced by forest fragmentation and to characterize composition and configuration of LULC mosaics, fragmentation indices were computed using Fragstats at class level, showing the signs of accelerated fragmentation. The outcome of the analysis revealed the effectiveness of geospatial tools coupled with landscape ecology in characterization and quantification of forest fragmentation and land cover changes. The present study provides a baseline database for sustainable conservation planning that will benefit the subsistence livelihoods in the region. Recommendations made based on the present analysis will help to recover forest and halt the pessimistic effects of fragmentation and land cover changes on biodiversity and ecosystem services in the region.

  6. Plans for Studies of (alpha,n) Reactions Relevant to Astrophysics via Inverse Reactions

    NASA Astrophysics Data System (ADS)

    Shima, T.; Nagai, Y.; Kii, T.; Kikuchi, T.; Baba, T.; Kobayashi, T.; Okazaki, F.

    1996-08-01

    (alpha,n) reactions in the keV energy region play important roles in astrophysical nucleosynthesis. In the primordial nucleosynthesis, it has been pointed out that a fluctuation of the baryon density distribution could be formed if the QCD phase transition from quark-gluon plasma to hadron gas occurred by first order. In that case the space was separated into the high density proton-rich zones and the low density neutron-rich ones, and in the neutron-rich zones nucleosynthesis could proceed beyond the mass gap at A = 8 via the reaction chains such as H-1(n,gamma)H-2(n,gamma)H-3(d,n)He-4(t,gamma)Li-7(n,gamma)Li-8(alpha,n)B- 11(n,ga mma)B-12(e(sup-)nu)C-12(n,gamma)C-13(n,gamma)C-14(n,gamma)C-15 ......, and so on. In the above nuclear reactions, the Li-8(alpha,n)B reaction plays quite a crucial role, because it can break through the mass gap at A = 8. (alpha,n) reactions of some light nuclei are also important as neutron sources for slow neutron capture process (s-process) of nucleosynthesis in stars. In low-mass and intermediate-mass (M < 10 Solar Mass) stars, neutrons are supposed to be supplied mainly by the C-13(alpha,n)O-16 reaction. On the other hand, the Ne-22(alpha,n)Mg-25 reaction is a candidate of the neutron source in massive stars with M > or = 10 Solar Mass. The contribution of the O-18(alpha,n)Ne-21 reaction to s-process in massive stars is still unknown. Since the temperatures of the above astrophysical sites correspond to the energy range of between a few ten and a few hundred keV, accurate data of the (alpha,n) reaction cross sections in the energy range are required for investigating nucleosynthesis. In order to measure these cross sections, not only direct (alpha,n) reactions but also inverse (n,alpha) reactions can be studied. In the following we would like to show experimental designs for studying several (alpha,n) reactions of astrophysical importance.

  7. The study on the reaction of rutile in Bayer liquor

    SciTech Connect

    Bi Shiwen; Li Dianfeng; Yang Yihong; Fu Gaofeng; Zhang Xin; Li Yan

    1996-10-01

    TiO{sub 2} is a harmful impurity in the digestion of producing alumina. TiO{sub 2} in bauxite usually exists in the forms of rutile, anatase and brookite. In this paper, the authors studied the reaction of rutile in sodium aluminate liquor, examined the effects of OH{sup {minus}} ion concentration, adding amount of CaO and temperature on the reaction, achieved the kinetics equation and calculated the activation energy of the reaction.

  8. A lower fragmentation mass scale for clumps in high redshift galaxies: a systematic numerical study

    NASA Astrophysics Data System (ADS)

    Tamburello, Valentina; Mayer, Lucio; Shen, Sijing; Wadsley, James

    2015-08-01

    We perform a systematic study of the effect of sub-grid physics, resolution and structural parameters on the fragmentation of gas-rich galaxy discs into massive star forming clumps due to gravitational instability. We use the state-of-the-art zoom-in cosmological hydrodynamical simulation ARGO (Fiacconi et al. 2015) to set up the initial conditions of our models, and then carry out 26 high resolution controlled simulations of high-z galaxies using the GASOLINE2 code, which includes a modern, numerically robust SPH implementation.We find that when blast-wave feedback is included, the formation of long-lived, gravitationally bound clumps requires disc gas fractions of at least 50% and massive discs, which should have Vmax > 200 km/s at z ˜ 2, more massive than the typical galaxies expected at those redshifts.Less than 50 Myr after formation, clumps have stellar masses in the range 4 × 106 - 5 × 107 M⊙.Formation of clumps with mass exceeding ˜108 M⊙ is a rare occurrence, since it requires mergers between multiple massive clumps, as we verified by tracing back in time the particles belonging to such clumps. Such mergers happen after a few orbital times (˜200-300 Myr), but normally clumps migrate inward and are tidally disrupted on shorter timescales.Clump sizes are in the range 100-500 pc. We argue that giant clumps identified in observations (˜109 M⊙ and 1 kpc in size) might either have a different origin, such as minor mergers and clumpy gas accretion, or their sizes and masses may be overestimated due to resolution issues.Using an analytical model, already developed to explain the fragmentation scale in gravitationally unstable 3D protoplanetary discs, we can predict fairly accurately the characteristic gaseous masses of clumps soon after fragmentation, when standard Toome analysis becomes invalid.Due to their modest size, clumps have little effect on bulge growth as they migrate to the center. In our unstable discs a small bulge can form irrespective of

  9. Fusion and quasifission studies in reactions forming Rn via evaporation residue measurements

    NASA Astrophysics Data System (ADS)

    Shamlath, A.; Prasad, E.; Madhavan, N.; Laveen, P. V.; Gehlot, J.; Nasirov, A. K.; Giardina, G.; Mandaglio, G.; Nath, S.; Banerjee, Tathagata; Vinodkumar, A. M.; Shareef, M.; Jhingan, A.; Varughese, T.; Kumar, Dvgrks; Devi, P. Sandya; Khushboo, Jisha, P.; Kumar, Neeraj; Hosamani, M. M.; Kailas, S.

    2017-03-01

    Background: Formation of the compound nucleus (CN) is highly suppressed by quasifission in heavy-ion collisions involving massive nuclei. Though considerable progress has been made in the understanding of fusion-fission and quasifission, the exact dependence of fusion probability on various entrance channel variables is not completely clear, which is very important for the synthesis of new heavy and superheavy elements. Purpose: To study the interplay between fusion and quasifission in reactions forming CN in the boundary region where the fusion probability starts to deviate from unity. Methods: Fusion evaporation residue cross sections were measured for the Si,3028+180Hf reactions using the Hybrid Recoil Mass Analyser at IUAC, New Delhi. Experimental data were compared with data from other reactions forming the same CN or isotopes of the CN. Theoretical calculations were performed using the dinuclear system and statistical models. Results: Reduced evaporation residue cross sections were observed for the reactions studied compared with the asymmetric reaction forming the same CN, indicating fusion suppression in more symmetric systems. The observations are consistent with fission fragment measurements performed in the same or similar systems. Larger ER cross sections are observed with increase in mass in the isotopic chain of the CN. Conclusions: Fusion probability varies significantly with the entrance channels in reactions forming the same CN. While complete fusion occurs for the 16O+194Pt reaction, the fusion probability drops to approximately 60 -70 % for the 30Si+180Hf and less than 20 % for the 50Ti+160Gd reactions, respectively, forming the same CN at similar excitation energies.

  10. Matrix isolation as a tool for studying interstellar chemical reactions

    NASA Technical Reports Server (NTRS)

    Ball, David W.; Ortman, Bryan J.; Hauge, Robert H.; Margrave, John L.

    1989-01-01

    Since the identification of the OH radical as an interstellar species, over 50 molecular species were identified as interstellar denizens. While identification of new species appears straightforward, an explanation for their mechanisms of formation is not. Most astronomers concede that large bodies like interstellar dust grains are necessary for adsorption of molecules and their energies of reactions, but many of the mechanistic steps are unknown and speculative. It is proposed that data from matrix isolation experiments involving the reactions of refractory materials (especially C, Si, and Fe atoms and clusters) with small molecules (mainly H2, H2O, CO, CO2) are particularly applicable to explaining mechanistic details of likely interstellar chemical reactions. In many cases, matrix isolation techniques are the sole method of studying such reactions; also in many cases, complexations and bond rearrangements yield molecules never before observed. The study of these reactions thus provides a logical basis for the mechanisms of interstellar reactions. A list of reactions is presented that would simulate interstellar chemical reactions. These reactions were studied using FTIR-matrix isolation techniques.

  11. Studies of hypersensitivity reactions to foods in infants and children.

    PubMed

    Bock, S A; Lee, W Y; Remigio, L K; May, C D

    1978-12-01

    In order to extend previous investigations of adverse reactions to foods performed at this institution, 68 children, aged 5 mo to 15 yr, were studied. All subjects reported a history of adverse reaction to ingestion of one or more of the 14 foods under study. Sixteen of 43 subjects, 3 yr of age or older, had 22 adverse reactions during 94 food challenges with one or more of the 14 foods. All reactions confirmed were to peanut or other nuts, milk, egg, and soy. Skin testing with 1:20 weight/volume concentrations of food extracts applied by the puncture technique produced a net wheal reaction 3 mm or greater in all subjects 3 yr of age or older in whom double-blind food challenges confirmed the history of adverse reaction. Thirteen of 25 children less than 3 yr of age manifested adverse reactions during 49 food challenges. Skin testing by puncture technique produced a net wheal 3 mm or greater in 9 children less than 3 yr of age in whom food challenge elicited a clinical response within 2 hr. One of 4 subjects less than 3 yr of age in whom the adverse reaction occurred more than 4 hr after food challenge exhibited a wheal to puncture skin test of 3 mm or greater. These studies suggest that at present double-blind food challenge is an indispensible tool for the unequivocal evaluation of adverse reactions to foods.

  12. Universality of fragment shapes

    PubMed Central

    Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

    2015-01-01

    The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism. PMID:25772300

  13. Universality of fragment shapes

    NASA Astrophysics Data System (ADS)

    Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

    2015-03-01

    The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism.

  14. Limiting Fragmentation Behavior of Projectile Helium (Z = 2) Fragments in Nucleus--Nucleus Interactions at 14.6 A GeV

    NASA Astrophysics Data System (ADS)

    Kumar, Ashwini; Singh, Gurmukh; Singh, Bhartendu K.

    2012-12-01

    An analysis of projectile helium (Z = 2) fragments based on 855 minimum-bias inelastic events induced by 14.6 A GeV 28Si beam in a nuclear emulsion is presented in order to test the hypothesis of limiting fragmentation. The projected angular distributions of projectile helium fragments have been fitted with Gaussian curves in individual helium reaction channels and also in different emulsion target events. Furthermore, average emission angle of projectile helium fragments has been studied in individual helium reaction channels with different emulsion target groups. On the basis of pseudo-rapidity distribution, an energy independent limiting fragmentation behavior of projectile helium fragments is also investigated in the fragmentation region.

  15. The GILL study: glycerin-induced local reactions in immunotherapy.

    PubMed

    Calabria, Christopher W; Coop, Christopher A; Tankersley, Michael S

    2008-01-01

    The mechanism of local reactions is not well defined. Glycerin, an excellent preservative used commonly in immunotherapy extracts, is a recognized irritant. This study was undertaken to examine whether higher glycerin concentration in immunotherapy extracts is associated with an increase in local reaction rates during immunotherapy. A retrospective analysis of electronic immunotherapy records over a 12-month period was performed from a single site. A small local reaction was defined as induration and/or erythema at the injection site smaller than or equal to the size of the patient's palm. A large local reaction was defined as a reaction larger than the patient's palm. Over the 12-month period, 360 patients received a total of 9678 immunotherapy injections. For all injections, the total local reaction rate was 16.3% (1574/9678), the small local reaction rate was 15.9% (1536/9678), and the large local reaction rate was 0.4% (38/9678). For aeroallergens, small local reaction rates increased significantly with increasing allergen concentrations, from 7.3% (1:1000 vol/vol) to 23.0% (1:1 vol/vol; P < .001). The small local reaction rate was higher with increasing allergen content but not higher glycerin concentration. Large local reactions were infrequent and did not significantly increase with allergen or glycerin concentration. Small local, but not large local, reaction rates increase with higher allergen concentration, number, and volume. Higher glycerin concentrations (even 50%) are not associated with significantly higher small or large local reaction rates.

  16. A DNA Metabarcoding Study of a Primate Dietary Diversity and Plasticity across Its Entire Fragmented Range

    PubMed Central

    Quéméré, Erwan; Hibert, Fabrice; Miquel, Christian; Lhuillier, Emeline; Rasolondraibe, Emmanuel; Champeau, Julie; Rabarivola, Clément; Nusbaumer, Louis; Chatelain, Cyrille; Gautier, Laurent; Ranirison, Patrick; Crouau-Roy, Brigitte; Taberlet, Pierre; Chikhi, Lounès

    2013-01-01

    In tropical regions, most primary ecosystems have been replaced by mosaic landscapes in which species must cope with a large shift in the distribution of their habitat and associated food resources. Primates are particularly vulnerable to habitat modifications. Most species persist in small fragments surrounded by complex human-mediated matrices whose structure and connectivity may strongly influence their dispersal and feeding behavior. Behavioral plasticity appears to be a crucial parameter governing the ability of organisms to exploit the resources offered by new matrix habitats and thus to persist in fragmented habitats. In this study, we were interested in the dietary plasticity of the golden-crowned sifaka (Propithecus tattersalli), an endangered species of lemur, found only in the Daraina region in north-eastern Madagascar. We used a DNA-based approach combining the barcoding concept and Illumina next-generation sequencing to (i) describe the species diet across its entire range and (ii) evaluate the influence of landscape heterogeneity on diet diversity and composition. Faeces from 96 individuals were sampled across the entire species range and their contents were analyzed using the trnL metabarcoding approach. In parallel, we built a large DNA reference database based on a checklist of the plant species of the Daraina region. Our results suggest that golden-crowned sifakas exhibit remarkable dietary diversity with at least 130 plant species belonging to 80 genera and 49 different families. We highlighted an influence of both habitat type and openness on diet composition suggesting a high flexibility of foraging strategies. Moreover, we observed the presence of numerous cultivated and naturalized plants in the faeces of groups living in forest edge areas. Overall, our findings support our initial expectation that P. tattersalli is able to cope with the current level of alteration of the landscape and confirm our previous results on the distribution and the

  17. A Method for Studying the Temperature Dependence of Dynamic Fracture and Fragmentation

    PubMed Central

    Jones, David R.; Chapman, David J.; Eakins, Daniel E.

    2015-01-01

    The dynamic fracture of a body is a late-stage phenomenon typically studied under simplified conditions, in which a sample is deformed under uniform stress and strain rate. This can be produced by evenly loading the inner surface of a cylinder. Due to the axial symmetry, as the cylinder expands the wall is placed into a tensile hoop stress that is uniform around the circumference. While there are various techniques to generate this expansion such as explosives, electromagnetic drive, and existing gas gun techniques they are all limited in the fact that the sample cylinder must be at room temperature. We present a new method using a gas gun that facilitates experiments on cylinders from 150 K to 800 K with a consistent, repeatable loading. These highly diagnosed experiments are used to examine the effect of temperature on the fracture mechanisms responsible for failure, and their resulting influence on fragmentation statistics. The experimental geometry employs a steel ogive located inside the target cylinder, with the tip located about halfway in. A single stage light gas gun is then used to launch a polycarbonate projectile into the cylinder at 1,000 m/sec-1. The projectile impacts and flows around the rigid ogive, driving the sample cylinder from the inside. The use of a non-deforming ogive insert allows us to install temperature control hardware inside the rear of the cylinder. Liquid nitrogen (LN2) is used for cooling and a resistive high current load for heating. Multiple channels of upshifted photon Doppler velocimetry (PDV) track the expansion velocity along the cylinder enabling direct comparison to computer simulations, while High speed imaging is used to measure the strain to failure. The recovered cylinder fragments are also subject to optical and electron microscopy to ascertain the failure mechanism. PMID:26168019

  18. Fundamental studies of retrograde reactions in direct liquefaction

    SciTech Connect

    Serio, M.A.; Solomon, P.R.; Bassilakis, R.; Kroo, E.

    1989-01-01

    Most of the proposed processing schemes for improving liquefaction yields involve favoring bond-breaking and radical stabilization reactions over the retrograde reactions. The retrograde reactions are often encountered before liquefaction temperatures are reached. The objective of this program is to elucidate and model the retrograde reaction chemistry in direct coal liquefaction through the application of experimental techniques and theoretical models which have been successfully employed at Advanced Fuel Research (AFR) and SRI International (a subcontractor) to understand and predict coal reaction behavior. The study of retrograde reactions is being done using an integrated approach using extensive characterization of the liquefaction chemistry of three kinds of systems: (1) model polymers; (2) coal; and (3) modified coals.

  19. Variational Flooding Study of a SN2 Reaction.

    PubMed

    Piccini, GiovanniMaria; McCarty, James J; Valsson, Omar; Parrinello, Michele

    2017-02-02

    We have studied the reaction dynamics of a prototypical organic reaction using a variationally optimized truncated bias to accelerate transitions between educt and product reactant states. The asymmetric SN2 nucleophilic substitution reaction of fluoromethane and chloromethane CH3F + Cl(-) ⇌ CH3Cl + F(-) is considered, and many independent biased molecular dynamics simulations have been performed at 600, 900, and 1200 K, collecting several hundred transitions at each temperature. The transition times and relative rate constants have been obtained for both reaction directions. The activation energies extracted from an Arrhenius plot compare well with standard static calculations.

  20. Transverse flow reactor studies of the dynamics of radical reactions

    SciTech Connect

    Macdonald, R.G.

    1993-12-01

    Radical reactions are in important in combustion chemistry; however, little state-specific information is available for these reactions. A new apparatus has been constructed to measure the dynamics of radical reactions. The unique feature of this apparatus is a transverse flow reactor in which an atom or radical of known concentration will be produced by pulsed laser photolysis of an appropriate precursor molecule. The time dependence of individual quantum states or products and/or reactants will be followed by rapid infrared laser absorption spectroscopy. The reaction H + O{sub 2} {yields} OH + O will be studied.

  1. Ab initio study of C + H3+ reactions

    NASA Technical Reports Server (NTRS)

    Talbi, D.; DeFrees, D. J.

    1991-01-01

    The reaction C + H3+ --> CH(+) + H2 is frequently used in models of dense interstellar cloud chemistry with the assumption that it is fast, i.e. there are no potential energy barriers inhibiting it. Ab initio molecular orbital study of the triplet CH3+ potential energy surface (triplet because the reactant carbon atom is a ground state triplet) supports this hypothesis. The reaction product is 3 pi CH+; the reaction is to exothermic even though the product is not in its electronic ground state. No path has been found on the potential energy surface for C + H3+ --> CH2(+) + H reaction.

  2. KINETIC STUDIES OF PHOTOTROPIC REACTIONS OF TRIPHENYLMETHANE LEUCONITRILES

    DTIC Science & Technology

    The mechanism of the phototropic reaction of triphenylmethane leuconitriles was studied in considerable detail. For the reaction between methyl...violet and cyande is phototropic and on excitation with ultraviolet light will revert to the dye and cyanide. The role of the solvent in the... phototropic process is considered. The excitation energy of the photoropic process is estabished. (Author)

  3. Women's reactions to interpersonal violence research: a longitudinal study.

    PubMed

    Edwards, Katie M; Probst, Danielle R; Tansill, Erin C; Gidycz, Christine A

    2013-01-01

    This study assessed women's immediate and long-term reactions to completing self-report measures of interpersonal violence. College women completed surveys at the beginning and end of a 2-month academic quarter for course credit. Results showed that 7.7% of participants experienced immediate negative emotional reactions to research participation. Greater immediate negative reactions were related to interpersonal victimization and psychological distress variables. Attrition from the study over the 2-month follow-up was not predicted by participants' immediate negative emotional reactions to the research or anticipation of future distress. Of the participants who returned for the follow-up, 2.1% of participants reported experiencing distress over the interim period as a result of their initial participation in the study. These long-term reactions were bivariately related to a number of victimization, psychological distress, and reaction variables measured at the first study session. However, in the regression analyses, only immediate negative emotional reactions to the research and anticipation of future distress predicted long-term negative emotional reactions.

  4. Design study for a magnetically supported reaction wheel

    NASA Technical Reports Server (NTRS)

    Stocking, G.; Dendy, J.; Sabnis, A.

    1974-01-01

    Results are described of a study program in which the characteristics of a magnetically supported reaction wheel are defined. Tradeoff analyses are presented for the principal components, which are then combined in several reaction wheel design concepts. A preliminary layout of the preferred configuration is presented along with calculated design and performance parameters. Recommendations are made for a prototype development program.

  5. Electromagnetic studies of nuclear structure and reactions

    SciTech Connect

    Hersman, F.W.; Dawson, J.F.; Heisenberg, J.H.; Calarco, J.R.

    1990-06-01

    This report contains papers on the following topics: giant resonance studies; deep inelastic scattering studies; high resolution nuclear structure work; and relativistic RPA; and field theory in the Schroedinger Representation.

  6. Fragmentation properties of metals

    SciTech Connect

    Grady, D.E.; Kipp, M.E.

    1996-06-01

    In the present study we are developing an experimental fracture material property test method specific to dynamic fragmentation. Spherical test samples of the metals of interest are subjected to controlled impulsive stress loads by acceleration to high velocities with a light-gas launcher facility and subsequent normal impact on thin plates. Motion, deformation and fragmentation of the test samples are diagnosed with multiple flash radiography methods. The impact plate materials are selected to be transparent to the x-ray method so that only test metal material is imaged. Through a systematic series of such tests, both strain-to-failure and fragmentation resistance properties are determined through this experimental method. Fragmentation property data for several steels, copper, aluminum, tantalum and titanium have been obtained to date. Aspects of the dynamic data have been analyzed with computational methods to achieve a better understanding of the processes leading to failure and fragmentation, and to test an existing computational fragmentation model.

  7. Systematic derivatization, mass fragmentation and acquisition studies in the analysis of chlorophenols, as their silyl derivatives by gas chromatography-mass spectrometry.

    PubMed

    Faludi, T; Andrási, N; Vasanits-Zsigrai, A; Záray, Gy; Molnár-Perl, I

    2013-08-09

    An exhaustive GC-MS sample preparation, derivatization, mass fragmentation and acquisition study was performed, for the simultaneous analysis of chlorophenols (CPs). Selected species were 2-CP, 3-CP, 4-CP, 3,5-dichlorophenol (diCP), 2,5-diCP, 2,6-diCP, 2,4-diCP, 2,3-diCP, 3,4-diCP 2,4,6-trichlorophenol (triCP), 2,4,5-triCP, 2,3,4-triCP, 2,3,4,6-tetrachlorophenol (tetraCP) and pentachlorophenol (pentaCP), in total 14 compounds. As novelties to the field, basic researches, like systematic derivatization, mass fragmentation and acquisition methods have been optimized for the trimethylsilyl (TMS) ether derivatives of CPs. The reactivity of chlorophenols with silylating agents has not been systematically analyzed. Here, we studied the reactivity of 14 chlorophenols with five silylating reagents. The three acquisition techniques, the full scan (FS), the multiple ion monitoring (MIM), and the currently optimized multiple reaction monitoring (MRM) methods, have been compared. We developed a new analytical approach, simultaneously monitoring the fragmentation pattern of the (35)Cl and the (37)Cl containing fragment ions both as precursor and as product ions. This principle resulted in remarkable specificity and sensitivity of detection and quantification; particularly in the cases of the tetraCP and pentaCP derivatives containing the (35)Cl and the (37)Cl fragment ions at an approximate ratio of <1:1. Detailed documentation of the loss of HCl via fragmentation processes, without decomposition of the benzene ring, was attributed to the "ring-walk" mechanism described first for monochlorophenol. Critical evaluation of the derivatization and acquisition protocols was collated and validated with the same characteristics. Data of six point calibration along with the corresponding relative standard deviation percentage (RSD%) values, in the line of FS, MIM and MRM methods (r(2): 0.9987, 0.9992, 0.9989; RSD%: 8.7, 5.6, 8.1), proved to be independent on the acquisition processes

  8. Studies of heavy ion reactions and transuranic nuclei. Progress report, August 1, 1979-July 31, 1980. [Univ. of Rochester, New York, 8/1/79-7/31/80

    SciTech Connect

    Huizenga, J.R.

    1980-07-01

    The study of heavy-ion reaction mechanisms at the SuperHILAC and LAMPF is reported. Preprints of five articles and manuscripts of four recent conference papers are given, along with complete citations of publications and a list of personnel. Significant work was performed in the following areas: the bombarding energy dependence of the /sup 209/Bi + /sup 136/Xe reaction; the fragment yields for specific Z and A for projectile-like fragments produced in the reaction of 8.3-MeV/u /sup 56/Fe ions with targets of /sup 56/Fe, /sup 165/Ho, /sup 209/Bi, and /sup 238/U; and time distributions of fragments from delayed fission after muon capture for muonic /sup 235/U, /sup 238/U, /sup 237/Np, /sup 239/Pu, and /sup 242/Pu. (RWR)

  9. Study of alpha one antitrypsin activity in lepra reaction.

    PubMed

    Sengupta, S R; Dhole, T N; Jahagirdar, V L; Yemul, V L; Chawhan, R N

    1983-04-01

    In our earlier study (Yemul et, al, 1983) we have reported elevation of serum alpha one antitrypsin levels in patients of lepromatous leprosy and lepra reaction. In this study estimation of serum alpha one antitrypsin levels in fifty lepra reaction patients (8 of type 1 and 42 of type II) and fifty age and sex matched healthy controls is described. Alpha one antitrypsin levels were elevated in lepra reaction patients (type I--mean value of 332 mg% and S.D. +/- 118.8 and type II--mean value of 450 mg% and S.D. +/- 73.7) when compared with the healthy controls (mean value of 285 mg% and S.D. +/- 66.05). The increase in levels in type II lepra reaction patients was statistically significant. The results are discussed to correlate the increased levels of alpha one antitrypsin and the high bacterial load leading to the release of various proteases in type II lepra reaction.

  10. Fundamental studies of retrograde reactions in direct liquefaction

    SciTech Connect

    Serio, M.A.; Solomon, P.R.; Kroo, E.; Charpenay, S.; Bassilakis, R.

    1991-12-17

    The overall objective of the program was to improve the understanding of retrograde reactions and their dependencies on coal rank and structure, and/or coal modifications and reaction conditions. Because retrograde reactions are competitive with bond breaking reactions, an understanding of both is required to shift the competition in favor of the latter. Related objectives were to clarify the conflicting observations reported in literature on such major topics as the role of oxygen groups in retrograde reactions and to provide a bridge from very fundamental studies on pure compounds to phenomenological studies on actual coal. This information was integrated into the FG-DVC model, which was improved and extended to the liquefaction context.

  11. Observation of anomalous reaction mean free paths of nuclear-projectile fragments in research emulsion from 2 A GeV heavy-ion collisions

    SciTech Connect

    Karant, Y.J.

    1981-07-01

    From an analysis of 1460 projectile fragment collisions in nuclear research emulsion exposed to 2.1 A GeV /sup 16/O and 1.9 A GeV /sup 56/Fe at the Bevalac, evidence is presented for the existence of an anomalously short interaction mean free path of projectile fragments for the first several cm after emission. The result is significant to beyond the 3 standard deviation confidence level.

  12. Surface plasmon field-enhanced fluorescence spectroscopy studies of primer extension reactions.

    PubMed

    Stengel, Gudrun; Knoll, Wolfgang

    2005-04-22

    Surface plasmon field-enhanced fluorescence spectroscopy (SPFS) utilizes the evanescent electromagnetic field of a surface plasmon to excite chromophors in close proximity to the surface. While conventional surface plasmon resonance spectroscopy allows the observation of surface reactions by means of refractive index changes, SPFS additionally provides a channel for the read-out of fluorescence changes. Thus, the detection limit for low mass compounds, whose adsorption is only accompanied by small refractive index changes, can be substantially improved by fluorescent labeling. In this study, we present the first example that utilizes SPFS to follow the dynamics of an enzymatic reaction. The elongation of surface-tethered DNA has been observed by the incorporation of Cy5-labeled nucleotides into the nascent strand by the action of DNA polymerase I (Klenow fragment). The technique offers a rapid way to determine the binding constant and the catalytic activity of a DNA processing enzyme, here exemplified by the Klenow fragment. Furthermore, the effect of mispaired bases in the primer/template duplex and the influence of different label densities have been studied. The resulting sensitivity for nucleotide incorporation, being in the femtomolar regime, combined with the specificity of the enzyme for fully complementary DNA duplexes suggest the application of this assay as a powerful tool for DNA detection.

  13. A complex reaction time study (Sternberg) in space flight

    NASA Technical Reports Server (NTRS)

    Thornton, W.; Uri, John; Moore, Tom

    1993-01-01

    Simple and complex (Sternberg) reaction time studies were flown on three and seven day Shuttle flights in 1985. Three subjects did selftesting with an onboard handheld calculator without difficulty. There was little change in simple reaction time. One subject demonstrated a decrease in the processing rate during space motion sickness while a second exhibited an increase in complex reaction time without a change in processing rate during a period of high work load. The population was too small to demonstrate significant changes. This study demonstrates the ease and practicality of such measurements and indicates the potential value of such studies in space.

  14. Isotope labelling to study molecular fragmentation during the dielectric barrier discharge wet reforming of methane

    NASA Astrophysics Data System (ADS)

    Montoro-Damas, Antonio M.; Gómez-Ramírez, Ana; Gonzalez-Elipe, Agustín R.; Cotrino, José

    2016-09-01

    Isotope labelling is used to study the wet plasma reforming of methane in a dielectric barrier discharge reactor using D2O and CH4 as reactants. Besides the formation of CO and hydrogen as main products, different partitions of H and D atoms are found in the hydrogen (i.e., H2, HD, D2), methane (i.e., CH4, CH3D and CH2D2) and water (D2O, DHO) molecules detected by mass spectrometry as outlet gases of the plasma process. The effect of operating parameters such as applied current, residence time and the addition of oxygen to the reaction mixture is correlated with the H/D distribution in these molecules, the overall reaction yield and the energetic efficiency of the process. The results prove the plasma formation of intermediate excited species that rendering water and methane instead of CO and hydrogen greatly contribute to decrease the overall energy efficiency of the reforming process.

  15. Evaluation of patients undergoing removal of glass fragments from injured hands: a retrospective study.

    PubMed

    Tuncer, Serdar; Ozcelik, Ismail Bulent; Mersa, Berkan; Kabakas, Fatih; Ozkan, Turker

    2011-08-01

    The hand is the body part most frequently injured by broken glass. Glass fragments lodged in soft tissues may result in numerous complications, such as infection, delayed healing, persistent pain, and late injury as a result of migration. Between 2005 and 2010, we removed 46 glass particles from the hands of 26 patients. The injuries were caused by the following: car windows broken during motor vehicle accidents in 11 patients (42%); fragments from broken glasses, dishes, or bottles in 9 (35%); the hand passing through glass in 5 (19%); and a fragment from a broken fluorescent lamp in 1 (4%) patient. Despite the efficacy of plain radiographs in detecting glass fragments, these are sometimes not obtained. Given the relatively low cost, accessibility, and efficacy of radiographs, and the adverse consequences of retained foreign bodies, the objections to obtaining radiographs should be few in diagnosing glass-related injuries of the hand.

  16. Orientation and alignment effects in ion-induced fragmentation of water: A triple coincidence study

    SciTech Connect

    Rajput, Jyoti; Safvan, C. P.

    2014-10-28

    The technique of recoil ion momentum spectroscopy is employed to determine the complete momentum vectors for three fragment dissociation channels, [D{sub 2}O]{sup (q+2)} → (D{sup +} + D{sup +} + O{sup q+}) with q = 1, 2, or 3 formed in collisions of isolated water molecules with 450 keV Xe{sup 9+} ions. The kinetic energy released in each of these dissociation channels is measured and angular correlations between the fragment momenta are determined. From the angular correlations of the three fragment ions with the direction of the incoming beam, a strong anisotropy in the emission of recoil fragments is reported. It is inferred that the molecular plane prefers to lie orthogonal to the incoming beam direction with certain orientations being more preferred than others and a clear signature of non-coplanar dissociation is also observed.

  17. Stab or throw? Biomechanical studies on the injuring potential of glass fragments.

    PubMed

    Sterzik, Vera; Kneubuehl, Beat; Rupp, Wolf; Bohnert, Michael

    2010-06-15

    During a Christmas party, two male guests started fighting. The perpetrator was allegedly pushed onto a glass table by the victim or fell into the table together with that man so that the glass top broke and caused a cut wound on the perpetrator's back. According to his statement he then threw a fragment of the broken glass table in the direction of the other man hitting him accidentally in a way so that the subclavian artery was severed and he died from exsanguination. Tests on the breaking characteristics of the glass table, the flying behaviour and the kinetics of thrown glass fragments conducted on various models supported the conclusion that the fatal injury on the victim's neck could not have been caused by a thrown glass fragment. It was much more likely that a stab with a blade-shaped glass fragment was the cause of the fatal injuries. (c) 2010 Elsevier Ireland Ltd. All rights reserved.

  18. Avian pancreatic polypeptide fragments refold to native aPP conformation when combined in solution: a CD and VCD study.

    PubMed

    Copps, Jeffrey; Murphy, Richard F; Lovas, Sándor

    2006-09-01

    An equimolar mixture of avian pancreatic polypeptide (aPP) fragments aPP(1-11)-NH2 and Ac-aPP(12-36) had an electronic circular dichroism (ECD) spectrum that was similar to that of whole aPP in H2O and even more so in 30% (v/v) trifluoroethanol (TFE) in 15 mM Na2HPO4, but was different from the sum of the spectra of the individual fragments. The vibrational circular dichroism (VCD) spectrum of the combined fragments in 30% (v/v) TFE in 15 mM Na2HPO4 in D2O was also similar to that of the intact aPP and unlike the sum of the VCD spectra of the fragments. The interaction of these fragments is thus sufficient to support the conformation of whole aPP. This study demonstrates that VCD, in combination with ECD, is useful for the study of protein-protein interactions.

  19. Measurement and management of human-induced patterns of forest fragmentation: a case study.

    PubMed

    Tole, Lise

    2006-06-01

    In many tropical developing countries, the twin pressures of population and poverty are resulting in substantial fragmentation of forests, increasing the probability of extinction for many species, Forest fragmentation occurs when large contiguous forests are perforated by small holes or broken up into edges and smaller patches to form a nonforested matrix of open spaces. Thus, forest fragmentation refers not only to the area of forest cleared, but also to the pattern of this clearance, the resulting forest's spatial properties. Both characteristics are important for species survivability. Apart from opening up forests to many abiotic and biotic influences, fragmentation can affect species dispersal and migration through its effects on forest connectivity. Landscape ecology conceptualizes connectivity as a gradient of critical thresholds, ranging from the large intact forest to the small unconnected forest patch. This article reports results from a multiple-scale analysis of forest fragmentation in Jamaica's Cockpit Country, an area of once contiguous forest now under threat from human encroachment. Spatial forest data derived from classification of ETM+ satellite imagery are used to measure fragmentation patterns representing various degrees of forest connectivity and density. The results suggest that, overall, 81% of the region is in forest. However, fragmentation patterns also suggest that this forest is riven with extensive perforations indicative of an early stage in the decline of contiguity. The results provided by the spatial fragmentation model are a first step in the design of effective conservation and rehabilitation plans for the area. The article concludes with a discussion of possible multiscale management options for the region.

  20. A gas gun based technique for studying the role of temperature in dynamic fracture and fragmentation

    NASA Astrophysics Data System (ADS)

    Jones, D. R.; Chapman, D. J.; Eakins, D. E.

    2013-11-01

    Presented in this work is a new experimental technique to facilitate studies of materials under uniform radial expansion at rates of strain typically seen in ballistic and impact studies (103 to 105 s-1) at temperatures around 100-1000 K. Previous work places a right-cylinder polymer insert in a sample cylinder, into which a matching polymer projectile is launched using a gas gun. The impact and resulting deformation of the polymers imparts radial momentum to the cylinder. This work replaces the polymer insert with a steel ogive. A polycarbonate projectile deforms around the insert and drives radial expansion. The uniform radial expansion created has a less complex interface than previous work as only one material is driving the cylinder wall. As deformation of the insert is no longer necessary, the opportunity to heat or cool the cylinder prior to expansion is now available for studies into the effect of temperature on fracture and fragmentation behavior. This paper describes the design of this new impact configuration alongside how strain rate and expansion profile can be controlled. Validation experiment results with 6061-T6 aluminum and Ti-6Al-4V cylinders using a variety of diagnostics are compared with numerical modelling, where the benefits of this technique in assisting development of material strength and failure models are discussed with methods to control the sample temperature.

  1. Direct studies of (α,p) reactions with HELIOS

    NASA Astrophysics Data System (ADS)

    Lai, Jianping; Blackmon, J. C.; Deibel, C. M.; Dimarco, D.; Gardiner, H.; Lauer, A.; Santiago-Gonzalez, D.; Williams, C.; Digiovine, B.; Greene, J.; Rohrer, J.; Helios Group At Argonne National Lab Collaboration

    2014-09-01

    In a variety of astrophysical processes, (α,p) type reactions have significant effects on final energy output and elemental abundances. However, only a handful of reactions have been measured due to technical limitations. Innovative new equipment and techniques, therefore, are necessary to extend measurement limits of these reactions rates. The HELIcal Orbit Spectrometer(HELIOS), serves as an important tool in studying reactions using radioactive ion beams at the Argonne Tandem Linac Accelerator System facility. With a specially designed gas target, we are able to study (α,p) reaction directly. HELIOS can separate protons from reactions with different energy states and the heavy recoils can be detected in coincidence by a high efficiency gas ionization detector. This combination has been successful in our pilot experiments. A series of (α,p) experiments using this setup in HELIOS are planned. We will start with 20Ne(α,p), which is crucial in Type Ia supernovae. A direct measurement of 30S(α,p), a key reaction in X ray burst, is also included in the near future plans and the beam development of 30S is in progress. Preliminary results will be presented. In a variety of astrophysical processes, (α,p) type reactions have significant effects on final energy output and elemental abundances. However, only a handful of reactions have been measured due to technical limitations. Innovative new equipment and techniques, therefore, are necessary to extend measurement limits of these reactions rates. The HELIcal Orbit Spectrometer(HELIOS), serves as an important tool in studying reactions using radioactive ion beams at the Argonne Tandem Linac Accelerator System facility. With a specially designed gas target, we are able to study (α,p) reaction directly. HELIOS can separate protons from reactions with different energy states and the heavy recoils can be detected in coincidence by a high efficiency gas ionization detector. This combination has been successful in our pilot

  2. In-situ study of Ag nanoparticle hydrosol optical spectra evolution during laser ablation/fragmentation

    NASA Astrophysics Data System (ADS)

    Šmejkal, P.; Pfleger, J.; Šišková, K.; Vlčková, B.; Dammer, O.; Šlouf, M.

    The results of in-situ monitoring of a laser fragmentation process of a largely polydisperse and morphologically heterogeneous citrate-reduced Ag hydrosol containing a fraction of Ag nanowires are presented. The laser fragmentation was performed using several wavelengths of the incident laser pulses (1064, 532 and 355 nm). Surface plasmon extinction spectra monitoring the nanoparticle fragmentation process were acquired pulse by pulse and related to transmission electron microscopy (TEM) images and statistical TEM image analysis of Ag nanoparticles collected in selected stages of the fragmentation. It was found that, due to different interactions of the laser pulses of various wavelengths with a specific fraction of the Ag nanoparticles in the hydrosol, the course of the fragmentation process depends on the wavelength, leading to different size distributions of the nanoparticles in the resulting hydrosol. The laser pulses of 532 nm wavelength are the most effective for the fragmentation process of the citrate-reduced Ag hydrosol, yielding the narrowest size distribution and the smallest mean radius of the Ag nanoparticles.

  3. Cartesian positioning system for localization of blast and ballistic fragments: a phantom-based pilot study.

    PubMed

    Folio, Les; Fischer, Tatjana; Shogan, Paul J; Frew, Michael; Bunger, Rolf; Provenzale, James M

    2011-11-01

    Our purpose was to demonstrate the consistency of radiologists' three-dimensional measurements of simulated blast fragment locations in vitro in an effort to objectively localize retained fragments and wound paths. We designed a phantom consisting of 10 nail heads (simulating blast fragments) glued to wooden pegs that were randomly situated at distances from a reference point within a plastic tub. The x, y, and z coordinates of simulated fragments were recorded in Cartesian 3-space relative to the reference point. Computed tomography images of the phantom were acquired. Differences in x, y, and z positions as determined by three observers were summed for each fragment. Agreement between recordings of coordinates across readers was assessed using the intraclass correlation coefficient. Summed differences in coordinate positions as determined by readers ranged between 0.00 and 1.204 cm (mean: 0.732 cm). Across readers, the intraclass correlation coefficient for each dimension was >0.99. We found excellent agreement among readers with minimal discrepancy of measured locations of simulated fragments. Our results provide a foundation for trajectory analysis necessary to lead to automated organ damage reporting for immediate assessment in the emergency department and for forensic investigation and long-term epidemiological analysis.

  4. The combined fragmentation and systematic molecular fragmentation methods.

    PubMed

    Collins, Michael A; Cvitkovic, Milan W; Bettens, Ryan P A

    2014-09-16

    Conspectus Chemistry, particularly organic chemistry, is mostly concerned with functional groups: amines, amides, alcohols, ketones, and so forth. This is because the reactivity of molecules can be categorized in terms of the reactions of these functional groups, and by the influence of other adjacent groups in the molecule. These simple truths ought to be reflected in the electronic structure and electronic energy of molecules, as reactivity is determined by electronic structure. However, sophisticated ab initio quantum calculations of the molecular electronic energy usually do not make these truths apparent. In recent years, several computational chemistry groups have discovered methods for estimating the electronic energy as a sum of the energies of small molecular fragments, or small sets of groups. By decomposing molecules into such fragments of adjacent functional groups, researchers can estimate the electronic energy to chemical accuracy; not just qualitative trends, but accurate enough to understand reactivity. In addition, this has the benefit of cutting down on both computational time and cost, as the necessary calculation time increases rapidly with an increasing number of electrons. Even with steady advances in computer technology, progress in the study of large molecules is slow. In this Account, we describe two related "fragmentation" methods for treating molecules, the combined fragmentation method (CFM) and systematic molecular fragmentation (SMF). In addition, we show how we can use the SMF approach to estimate the energy and properties of nonconducting crystals, by fragmenting the periodic crystal structure into relatively small pieces. A large part of this Account is devoted to simple overviews of how the methods work. We also discuss the application of these approaches to calculating reactivity and other useful properties, such as the NMR and vibrational spectra of molecules and crystals. These applications rely on the ability of these

  5. Genotypic characterization of Indian isolates of infectious bursal disease virus strains by reverse transcription-polymerase chain reaction combined with restriction fragment length polymorphism analysis.

    PubMed

    Priyadharsini, C V; Senthilkumar, T M A; Raja, P; Kumanan, K

    2016-03-01

    The reverse transcription PCR (RT-PCR) combined with restriction fragment length polymorphism (RFLP) is used for the differentiation of classical virulent (cv), virulent (v) and very virulent (vv) strains of infectious bursal disease virus (IBDV) isolates from chicken bursal tissues in southern states of India. In the present study, six different isolates (MB11, HY12, PY12, BGE14, VCN14 and NKL14) of IBDV strains were subjected for genotyping along with vaccine virus (Georgia, intermediate strain) using RT-PCR for amplification of a 743 bp sequence in the hypervariable region of VP2 gene followed by restriction enzyme digestion with 5 different restriction enzymes (BspMI, SacI, HhaI, StuI and SspI). The RT-PCR products obtained from vvIBDV strains were digested by SspI enzyme except PY12, BGE14 and MB11 isolates. The SacI digested the isolate MB11, PY12 and the vaccine strain, but it did not cleave the very virulent isolates of IBDV. HhaI cleaved all the isolates with different restriction profile patterns. StuI digested all the vvIBDV isolates and BspMI was not able to differentiate field isolates from vaccine strain. Though RT-PCR combined with RFLP is a genotypic method, further confirmation of serotypes to distinguish the vvIBDV from cvIBDV has to be carried out using pathogenicity studies.

  6. Fragmentation of Chitosan by Acids

    PubMed Central

    Arul, Joseph; Charlet, Gérard

    2013-01-01

    Fragmentation of chitosan in aqueous solution by hydrochloric acid was investigated. The kinetics of fragmentation, the number of chain scissions, and polydispersity of the fragments were followed by viscometry and size exclusion chromatography. The chemical structure and the degree of N-acetylation (DA) of the original chitosan and its fragments were examined by 1H NMR spectroscopy and elemental analysis. The kinetic data indicates that the reaction was of first order. The results of polydispersity and the DA suggest that the selected experimental conditions (temperature and concentration of acid) were appropriate to obtain the fragments having the polydispersity and the DA similar to or slightly different from those of the original one. A procedure to estimate molecular weight of fragments as well as the number of chain scissions of the fragments under the experimental conditions was also proposed. PMID:24302858

  7. Study of the {sup 12}C ({sup 8}B, {sup 7}Be)X knockout reaction at intermediate energies

    SciTech Connect

    Sadeghi, H. Ghambari, M.; Fereidonnejad, R.

    2016-01-15

    The breakup reactions of {sup 8}B on a {sup 12}C target at 142, 285, 790, and 936MeV/nucleon have been studied. One-proton-removal cross sections, leading to the production of {sup 7}Be fragments in the ground and first excited states (at 0.429MeV), and the longitudinal momentum distributions of the {sup 7}Be fragments are obtained in the Eikonal approximation of the Glauber Model. The results of the calculations including the contribution of the {sup 7}Be to the ground and first excited states of {sup 8}B are compared with the available experimental data. One-proton-removal cross section for the {sup 12}C({sup 8}B, {sup 7}Be)X knockout reaction at 142, 285, 790, and 936 MeV/nucleon energy has been calculated. {sup 8}B and {sup 7}Be cross sections and momentum distribution are in a good agreement with available data.

  8. Theoretical Study of Sodium-Water Surface Reaction Mechanism

    NASA Astrophysics Data System (ADS)

    Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR).

  9. Jet-A reaction mechanism study for combustion application

    NASA Technical Reports Server (NTRS)

    Lee, Chi-Ming; Kundu, Krishna; Acosta, Waldo

    1991-01-01

    Simplified chemical kinetic reaction mechanisms for the combustion of Jet A fuel was studied. Initially, 40 reacting species and 118 elementary chemical reactions were chosen based on a literature review. Through a sensitivity analysis with the use of LSENS General Kinetics and Sensitivity Analysis Code, 16 species and 21 elementary chemical reactions were determined from this study. This mechanism is first justified by comparison of calculated ignition delay time with the available shock tube data, then it is validated by comparison of calculated emissions from the plug flow reactor code with in-house flame tube data.

  10. Jet-A reaction mechanism study for combustion application

    NASA Technical Reports Server (NTRS)

    Lee, Chi-Ming; Kundu, Krishna; Acosta, Waldo

    1991-01-01

    Simplified chemical kinetic reaction mechanisms for the combustion of Jet A fuel are studied. Initially 40 reacting species and 118 elementary chemical reactions were chosen based on the literature review of previous works. Through a sensitivity analysis with the use of LSENS General Kinetics and Sensitivity Analysis Code, 16 species and 21 elementary chemical reactions were determined from this study. This mechanism is first justified by comparison of calculated ignition delay time with available shock tube data, then it is validated by comparison of calculated emissions from plug flow reactor code with in-house flame tube data.

  11. Jet-A reaction mechanism study for combustion application

    NASA Technical Reports Server (NTRS)

    Lee, Chi-Ming; Kundu, Krishna; Acosta, Waldo

    1991-01-01

    Simplified chemical kinetic reaction mechanisms for the combustion of Jet A fuel are studied. Initially 40 reacting species and 118 elementary chemical reactions were chosen based on the literature review of previous works. Through a sensitivity analysis with the use of LSENS General Kinetics and Sensitivity Analysis Code, 16 species and 21 elementary chemical reactions were determined from this study. This mechanism is first justified by comparison of calculated ignition delay time with available shock tube data, then it is validated by comparison of calculated emissions from plug flow reactor code with in-house flame tube data.

  12. Effects of target fragmentation on evaluation of LET spectra from space radiations: implications for space radiation protection studies

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Wilson, J. W.; Shinn, J. L.; Badavi, F. F.; Badhwar, G. D.

    1996-01-01

    We present calculations of linear energy transfer (LET) spectra in low earth orbit from galactic cosmic rays and trapped protons using the HZETRN/BRYNTRN computer code. The emphasis of our calculations is on the analysis of the effects of secondary nuclei produced through target fragmentation in the spacecraft shield or detectors. Recent improvements in the HZETRN/BRYNTRN radiation transport computer code are described. Calculations show that at large values of LET (> 100 keV/micrometer) the LET spectra seen in free space and low earth orbit (LEO) are dominated by target fragments and not the primary nuclei. Although the evaluation of microdosimetric spectra is not considered here, calculations of LET spectra support that the large lineal energy (y) events are dominated by the target fragments. Finally, we discuss the situation for interplanetary exposures to galactic cosmic rays and show that current radiation transport codes predict that in the region of high LET values the LET spectra at significant shield depths (> 10 g/cm2 of Al) is greatly modified by target fragments. These results suggest that studies of track structure and biological response of space radiation should place emphasis on short tracks of medium charge fragments produced in the human body by high energy protons and neutrons.

  13. Effects of target fragmentation on evaluation of LET spectra from space radiations: implications for space radiation protection studies

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Wilson, J. W.; Shinn, J. L.; Badavi, F. F.; Badhwar, G. D.

    1996-01-01

    We present calculations of linear energy transfer (LET) spectra in low earth orbit from galactic cosmic rays and trapped protons using the HZETRN/BRYNTRN computer code. The emphasis of our calculations is on the analysis of the effects of secondary nuclei produced through target fragmentation in the spacecraft shield or detectors. Recent improvements in the HZETRN/BRYNTRN radiation transport computer code are described. Calculations show that at large values of LET (> 100 keV/micrometer) the LET spectra seen in free space and low earth orbit (LEO) are dominated by target fragments and not the primary nuclei. Although the evaluation of microdosimetric spectra is not considered here, calculations of LET spectra support that the large lineal energy (y) events are dominated by the target fragments. Finally, we discuss the situation for interplanetary exposures to galactic cosmic rays and show that current radiation transport codes predict that in the region of high LET values the LET spectra at significant shield depths (> 10 g/cm2 of Al) is greatly modified by target fragments. These results suggest that studies of track structure and biological response of space radiation should place emphasis on short tracks of medium charge fragments produced in the human body by high energy protons and neutrons.

  14. Severe Cutaneous Adverse Drug Reactions: A Clinicoepidemiological Study

    PubMed Central

    Sasidharanpillai, Sarita; Riyaz, Najeeba; Khader, Anza; Rajan, Uma; Binitha, Manikoth P; Sureshan, Deepthi N

    2015-01-01

    Background: Drug eruptions range from transient erythema to the life threatening severe cutaneous adverse reactions (SCAR) that encompass Stevens–Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), acute generalized exanthematous pustulosis (AGEP) and drug reaction with eosinophilia and systemic symptoms complex (DRESS). Aims and Objectives: To study the clinical and epidemiological aspects of cutaneous adverse drug reactions (CADR). Materials and Methods: Ethical clearance was obtained from the institutional ethics committee. All patients admitted in the Dermatology ward of our tertiary care hospital with CADR (those who fit in the category of probable or possible drug reaction as per WHO casuality assessment) from first September 2011 to 31st August 2012 were included in this cross sectional study after obtaining written informed consent. The drug reaction patterns observed in the study population were determined and the common offending drugs were identified. Results: In the study, population of males outnumbered females and the majority were between 46 and 60 years of age. The commonest reaction pattern observed was SJS- TEN spectrum of illness and aromatic anticonvulsants were the common offending drugs. Prompt withdrawal of the culprit drug and administration of systemic steroids with or without I/V Ig reverted the adverse reaction in all except one. Conclusion: Severe drug reactions predominated as the study population was comprised of inpatients of a tertiary referral centre. Though; previous authors had reported a mortality rate of up to 20% in DRESS, all our patients with this reaction pattern, responded well to treatment. The mortality rate among TEN cases was much lower than the previous reports. Early diagnosis, prompt withdrawal of the suspected drug, careful monitoring for development of complications and immediate intervention can improve the prognosis of CADR. PMID:25657416

  15. Quantum mechanical/effective fragment potential (QM/EFP) study of phosphate monoester aminolysis in aqueous solution.

    PubMed

    Ferreira, Dalva E C; Florentino, Bruno P D; Rocha, Willian R; Nome, Faruk

    2009-11-05

    In this work, we investigated the P-O bond cleavage of dianionic p-nitrophenyl phosphate monoester (p-NPP), with attack of aqueous methylamine on phosphorus, by using the hybrid quantum mechanical/effective fragment potential (QM/EFP) approach. We explored the structures, energetic properties, reaction mechanism, and charge distribution along the entire reaction coordinate. Our B3LYP/6-31++G(d,p)/EFP results show that the cleavage of the P-O bond of p-NPP proceeds through a concerted mechanism with an activation energy of about 26 kcal/mol and an activation free energy at 39 degrees C of 23.6 kcal/mol, in good agreement with the experimental value of 27 kcal/mol. The reaction involves a trigonal bipyramidal (TBP) transition state with less initial bonding to the nucleophile than to the leaving group. The extent of the P-O(nitrophenolate) bond dissociation at the transition state, with methylamine as the nucleophile, is less than that with OH(-). The computed charge distribution along the reaction coordinate is consistent with a progressive charge transfer from the nitrogen atom of methylamine to the phosphate unit along the reaction coordinate. A new strategy to build the initial EFP cluster, by running a classical Monte Carlo simulation and analyzing the center-of-mass radial pair distribution function, was also used.

  16. Theoretical Studies of Elementary Hydrocarbon Species and Their Reactions

    SciTech Connect

    Allen, Wesley D.; Schaefer, III, Henry F.

    2015-11-14

    This is the final report of the theoretical studies of elementary hydrocarbon species and their reactions. Part A has a bibliography of publications supported by DOE from 2010 to 2016 and Part B goes into recent research highlights.

  17. Atmospheric chemistry: Laboratory studies of kinetics of important reactions

    NASA Astrophysics Data System (ADS)

    Smith, S. J.

    Experiments to measure the rate constants for some reactions of the atmospherically important nitrate radical (NO3) are described using the discharge-flow technique. The nitrate radical was monitored by optical absorption at lambda = 662 nm. The reactions of NO3 with some stable organic and inorganic substrates are reported. The temperature dependences of some of the rate constants were also determined (298 less than T less than 523 K). In most cases, computer simulation was used to extract the rate constant for the primary process because the time-dependent behavior of (NO3) was affected by secondary reactions of NO3 with products of the primary interaction. The Arrhenius parameter for the reactions of NO3 with CH3CH3, CH2CH2, CH3OH, CHCl3, and HCl were determined. The activation energies for the reactions studied between NO3 and some alkynes are presented along with the corresponding pre-exponential factors. Some reactions were studied at room temperature (298 plus or minus 2 K) only and the rate constants found (in units of cubic cm/molecule sec) are: buta-1,3-diene (1.8 x 10 (exp -13), isobutene (2.8 x 10 (exp -13), HBr (1.3 x 10 (exp -15) and hex-2-yne (3.0 x 10 (exp -14). Non-Arrhenius behavior was found in the reactions of NO3 with n-butane, isobutane and propene. The empirical variation of these rate constants with temperature is presented. The curvature of the Arrhenius plots is discussed in terms of (1) a temperature-dependent pre-exponential factor, and (2) the possibility that two competing channels, possessing differing activation energies, exist for each reaction. The atmospheric implications of these reactions are discussed with reference to the nighttime production of nitric acid and the importance of the these reactions as loss processes for NO3.

  18. Fragmentation of [Ni(NO3)3](-): A Study of Nickel-Oxygen Bonding and Oxidation States in Nickel Oxide Fragments.

    PubMed

    Hester, Thomas H; Albury, Rachael M; Pruitt, Carrie Jo M; Goebbert, Daniel J

    2016-07-05

    Gas-phase nickel nitrate anions are known to produce nickel oxide nitrate anions, [NiOx(NO3)y](-) upon fragmentation. The goal of this study was to investigate the properties of nickel oxide nitrate complexes generated by electrospray ionization using a tandem quadrupole mass spectrometer and theoretical calculations. The [Ni(NO3)3](-) ion undergoes sequential NO2(•) elimination to yield [NiO(NO3)2](-) and [NiO2(NO3)](-), followed by elimination of O2. The electronic structure of the nickel oxide core influences decomposition. Calculations indicate electron density from oxygen is delocalized onto the metal, yielding a partially oxidized oxygen in [NiO(NO3)2](-). Theoretical studies suggest the mechanism for O2 elimination from [NiO2(NO3)](-) involves oxygen atom transfer from a nitrate ligand to yield an intermediate, [NiO(O2)(NO2)](-), containing an oxygen radical anion ligand, O(•-), a superoxide ligand, O2(•-), and a nitrite ligand bound to Ni(2+). Electron transfer from superoxide partially reduces both the metal and oxygen and yields the energetically favored [NiO(NO2)](-) + O2 products.

  19. Crossed molecular beam studies of atmospheric chemical reaction dynamics

    SciTech Connect

    Zhang, Jingsong

    1993-04-01

    The dynamics of several elementary chemical reactions that are important in atmospheric chemistry are investigated. The reactive scattering of ground state chlorine or bromine atoms with ozone molecules and ground state chlorine atoms with nitrogen dioxide molecules is studied using a crossed molecular beams apparatus with a rotatable mass spectrometer detector. The Cl + O3 → ClO + O2 reaction has been studied at four collision energies ranging from 6 kcal/mole to 32 kcal/mole. The derived product center-of-mass angular and translational energy distributions show that the reaction has a direct reaction mechanism and that there is a strong repulsion on the exit channel. The ClO product is sideways and forward scattered with respect to the Cl atom, and the translational energy release is large. The Cl atom is most likely to attack the terminal oxygen atom of the ozone molecule. The Br + O3 → ClO + O2 reaction has been studied at five collision energies ranging from 5 kcal/mole to 26 kcal/mole. The derived product center-of-mass angular and translational energy distributions are quite similar to those in the Cl + O3 reaction. The Br + O3 reaction has a direct reaction mechanism similar to that of the Cl + O3 reaction. The electronic structure of the ozone molecule seems to play the central role in determining the reaction mechanism in atomic radical reactions with the ozone molecule. The Cl + NO2 → ClO + NO reaction has been studied at three collision energies ranging from 10.6 kcal/mole to 22.4 kcal/mole. The center-of-mass angular distribution has some forward-backward symmetry, and the product translational energy release is quite large. The reaction proceeds through a short-lived complex whose lifetime is less than one rotational period. The experimental results seem to show that the Cl atom mainly attacks the oxygen atom instead of the nitrogen atom of the NO2

  20. Study of Structure and Small-Scale Fragmentation in TMC-1

    NASA Technical Reports Server (NTRS)

    Langer, W. D.; Velusamy, T.; Kuiper, T. B.; Levin, S.; Olsen, E.; Migenes, V.

    1995-01-01

    Large-scale C(sup 18)O maps show that the Taurus molecular cloud 1 (TMC-1) has numerous cores located along a ridge which extends about 12 minutes by at least 35 minutes. The cores traced by C(sup 18)O are about a few arcminutes (0.1-0.2 pc) in extent, typically contain about 0.5-3 solar mass, and are probably gravitationally bound. We present a detailed study of the small-scale fragmentary structure of one of these cores, called core D, within TMC-1 using very high spectral and spatial resolution maps of CCS and CS. The CCS lines are excellent tracers for investigating the density, temperature, and velocity structure in dense cores. The high spectral resolution, 0.008 km /s, data consist mainly of single-dish, Nyquist-sampled maps of CCS at 22 GHz with 45 sec spatial resolution taken with NASA's 70 m DSN antenna at Goldstone. The high spatial resolution spectral line maps were made with the Very Large Array (9 sec resolution) at 22 GHz and with the OVRO millimeter array in CCS and CS at 93 GHz and 98 GHz, respectively, with 6 sec resolution. These maps are supplemented with single-dish observations of CCS and CC(sup 34)S spectra at 33 GHz using a NASA 34 m DSN antenna, CCS 93 GHz, C(sup 34)S (2-1), and C(sup 18)O (1-0) single-dish observations made with the AT&T Bell Laboratories 7 m antenna. Our high spectral and spatial CCS and CS maps show that core D is highly fragmented. The single-dish CCS observations map out several clumps which range in size from approx. 45 sec to 90 sec (0.03-0.06 pc). These clumps have very narrow intrinsic line widths, 0.11-0.25 km/s, slightly larger than the thermal line width for CCS at 10 K, and masses about 0.03-0.2 solar mass. Interferometer observations of some of these clumps show that they have considerable additional internal structure, consisting of several condensations ranging in size from approx. 10 sec- 30 sec (0.007-0.021 pc), also with narrow line widths. The mass of these smallest fragments is of order 0.01 solar mass

  1. Cosmetic micromanipulation of vitrified-warmed cleavage stage embryos does not improve ART outcomes: An ultrastructural study of fragments.

    PubMed

    Safari, Somayyeh; Khalili, Mohammad Ali; Barekati, Zeinab; Halvaei, Iman; Anvari, Morteza; Nottola, Stefania A

    2017-09-01

    The aim was to study the ultrastructure of cytoplasmic fragments along with the effect of cosmetic micromanipulation (CM) on the morphology and development of vitrified-warmed embryos as well as assisted reproductive technology (ART) outcomes. A total of 96 frozen embryo transfer (FET) cycles were included in this prospective randomized study. They were divided into three groups of CM (n=32), sham (n=32) and control (n=32). In the CM group, the vitrified- warmed embryos were subjected to fragments and coarse granules removal (cosmetic micromanipulation) after laser assisted zona hatching (LAH); sham group subjected only to LAH and no intervention was taken for the control group. Fragmented embryo was evaluated by transmission electron microscopy (TEM). Significant improvement was observed in the morphological parameters, such as fragmentation degrees, evenness of the blastomeres and embryo grade during the subsequent development, after applying cosmetic micromanipulation, when compared to sham or control groups (P=0.00001). However, there were no differences in the clinical outcomes amongst the three studied groups e.g. the rates of clinical, ongoing and multiple pregnancies, implantation, delivery and live birth. In fine structure view, fragments exhibited uniform cytoplasmic texture containing majority of organelles that were observed in normal blastomeres including mitochondria. In conclusion, application of cosmetic micromanipulation in low-grade vitrified-warmed embryos showed significant improvement on embryo morphology parameters; however, did not result in noticeable improvements in clinical outcomes of the patients undergoing ART program. In addition, embryo vitrification had no adverse effects on fine structure of the fragments. Copyright © 2017 Society for Biology of Reproduction & the Institute of Animal Reproduction and Food Research of Polish Academy of Sciences in Olsztyn. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  2. Studies of alpha-induced astrophysical reactions at CRIB

    SciTech Connect

    Yamaguchi, H.; Hashimoto, T.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kubono, S.

    2010-08-12

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Using the RI beams at CRIB, many measurements on proton alpha resonance scatterings, ({alpha},p) reactions, and others were performed in recent years mainly for studying astrophysical reactions and exotic nuclear structure. Among them, the results on the {sup 7}Li+{alpha} resonance scatterings are presented.

  3. Bulk plasma fragmentation in a C{sub 4}F{sub 8} inductively coupled plasma: A hybrid modeling study

    SciTech Connect

    Zhao, Shu-Xia; Zhang, Yu-Ru; Gao, Fei; Wang, You-Nian; Bogaerts, Annemie

    2015-06-28

    A hybrid model is used to investigate the fragmentation of C{sub 4}F{sub 8} inductive discharges. Indeed, the resulting reactive species are crucial for the optimization of the Si-based etching process, since they determine the mechanisms of fluorination, polymerization, and sputtering. In this paper, we present the dissociation degree, the density ratio of F vs. C{sub x}F{sub y} (i.e., fluorocarbon (fc) neutrals), the neutral vs. positive ion density ratio, details on the neutral and ion components, and fractions of various fc neutrals (or ions) in the total fc neutral (or ion) density in a C{sub 4}F{sub 8} inductively coupled plasma source, as well as the effect of pressure and power on these results. To analyze the fragmentation behavior, the electron density and temperature and electron energy probability function (EEPF) are investigated. Moreover, the main electron-impact generation sources for all considered neutrals and ions are determined from the complicated C{sub 4}F{sub 8} reaction set used in the model. The C{sub 4}F{sub 8} plasma fragmentation is explained, taking into account many factors, such as the EEPF characteristics, the dominance of primary and secondary processes, and the thresholds of dissociation and ionization. The simulation results are compared with experiments from literature, and reasonable agreement is obtained. Some discrepancies are observed, which can probably be attributed to the simplified polymer surface kinetics assumed in the model.

  4. The Role of Pebble Fragmentation in Planetesimal Formation. I. Experimental Study

    NASA Astrophysics Data System (ADS)

    Bukhari Syed, M.; Blum, J.; Wahlberg Jansson, K.; Johansen, A.

    2017-01-01

    Previous work on protoplanetary dust growth shows a halt at centimeter sizes owing to the occurrence of bouncing at velocities of ≳0.1 m s‑1 and fragmentation at velocities ≳1 m s‑1. To overcome these barriers, spatial concentration of centimeter-sized dust pebbles and subsequent gravitational collapse have been proposed. However, numerical investigations have shown that dust aggregates may undergo fragmentation during the gravitational collapse phase. This fragmentation in turn changes the size distribution of the solids and thus must be taken into account in order to understand the properties of the planetesimals that form. To explore the fate of dust pebbles undergoing fragmenting collisions, we conducted laboratory experiments on dust-aggregate collisions with a focus on establishing a collision model for this stage of planetesimal formation. In our experiments, we analyzed collisions of dust aggregates with masses between 0.7 and 91 g mass ratios between target and projectile from 1 to 126 at a fixed porosity of 65%, within the velocity range of 1.5–8.7 m s‑1, at low atmospheric pressure of ∼10‑3 mbar, and in free-fall conditions. We derived the mass of the largest fragment, the fragment size/mass distribution, and the efficiency of mass transfer as a function of collision velocity and projectile/target aggregate size. Moreover, we give recipes for an easy-to-use fragmentation and mass-transfer model for further use in modeling work. In a companion paper, we use the experimental findings and the derived dust-aggregate collision model to investigate the fate of dust pebbles during gravitational collapse.

  5. Performance Assessment of the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism Method for Rapid Detection of Susceptibility to Ethambutol and Molecular Prediction of Extensively Drug-resistant Tuberculosis in Clinical Isolates of Mycobacterium tuberculosis.

    PubMed

    Arjomandzadegan, M; Nazari, R; Zolfaghari, M R; Taherahmadi, M; Sadrnia, M; Titov, L P; Ahmadi, A; Shojapoor, M

    2015-09-01

    The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was employed for rapid detection of ethambutol (EMB) resistant clinical isolates of Mycobacterium tuberculosis. From 182 clinical isolates of M tuberculosis collected from different regions, 103 strains were entered in the investigation. DNA was extracted by Chelex 100 method and PCR was performed using specific primers for embB gene. Polymerase chain reaction products were digested with HaeIII and NlaII restriction endonucleases and the patterns of restriction fragments were analysed. Some randomly selected samples were sequenced. Out of 103 studied strains, 52 were resistant to EMB. The cases of secondary tuberculosis were 53 (51.50 ± 1.77%), and primary cases 50 (48.50 ± 1.77%; p > 0.05). From 63 extensively drug-resistant (XDR), pre-XDR and multidrug-resistant (MDR) isolates, 27 (87%), 18 (81.8%) and 7 (70%) strains were resistant to EMB, respectively. Results of PCR-RFLP method showed that from 27R EMB XDR isolates, 13 (sensitivity 48% with CI: 0.307, 0.66 and specificity 100%), from 18R EMB pre-XDR strains, 4 (sensitivity 22% with CI: 0.09, 0.45 and specificity 100%) and of 7R EMB MDR, 2 (sensitivity 28% with CI: 0.082, 0.64 and specificity 100%) had mutation in ATG-Met codon 306. Results of sequencing were concordant with RFLP method. Overall, sensitivity of the molecular method was 36.5% (CI: 0.09, 0.45) and specificity 100%. None of the 40 pansusceptible strains was embB306 mutants. Extensively drug-resistant strains had a higher proportion of embB306 mutants (43%) than pre-XDR and MDR isolates (odds ratio 6.78; p < 0.001). Fast detection of susceptibility to EMB drug is possible by PCR-RFLP. The embB306 locus is a candidate marker for rapid prediction of high resistance consisting of MDR and XDR forms to anti-tuberculosis drugs using this method.

  6. Performance Assessment of the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism Method for Rapid Detection of Susceptibility to Ethambutol and Molecular Prediction of Extensively Drug-resistant Tuberculosis in Clinical Isolates of Mycobacterium tuberculosis

    PubMed Central

    Arjomandzadegan, M; Nazari, R; Zolfaghari, MR; Taherahmadi, M; Sadrnia, M; Titov, LP; Ahmadi, A; Shojapoor, M

    2015-01-01

    ABSTRACT Introduction: The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was employed for rapid detection of ethambutol (EMB) resistant clinical isolates of Mycobacterium tuberculosis. Materials and Methods: From 182 clinical isolates of M tuberculosis collected from different regions, 103 strains were entered in the investigation. DNA was extracted by Chelex 100 method and PCR was performed using specific primers for embB gene. Polymerase chain reaction products were digested with HaeIII and NlaII restriction endonucleases and the patterns of restriction fragments were analysed. Some randomly selected samples were sequenced. Results: Out of 103 studied strains, 52 were resistant to EMB. The cases of secondary tuberculosis were 53 (51.50 ± 1.77%), and primary cases 50 (48.50 ± 1.77%; p > 0.05). From 63 extensively drug-resistant (XDR), pre-XDR and multidrug-resistant (MDR) isolates, 27 (87%), 18 (81.8%) and 7 (70%) strains were resistant to EMB, respectively. Results of PCR-RFLP method showed that from 27R EMB XDR isolates, 13 (sensitivity 48% with CI: 0.307, 0.66 and specificity 100%), from 18R EMB pre-XDR strains, 4 (sensitivity 22% with CI: 0.09, 0.45 and specificity 100%) and of 7R EMB MDR, 2 (sensitivity 28% with CI: 0.082, 0.64 and specificity 100%) had mutation in ATG-Met codon 306. Results of sequencing were concordant with RFLP method. Overall, sensitivity of the molecular method was 36.5% (CI: 0.09, 0.45) and specificity 100%. None of the 40 pansusceptible strains was embB306 mutants. Extensively drug-resistant strains had a higher proportion of embB306 mutants (43%) than pre-XDR and MDR isolates (odds ratio 6.78; p < 0.001). Conclusion: Fast detection of susceptibility to EMB drug is possible by PCR-RFLP. The embB306 locus is a candidate marker for rapid prediction of high resistance of MDR and XDR forms to anti-tuberculosis drugs using this method. PMID:26624582

  7. Biodistribution and radioimmunoscintigraphy studies of renal cell carcinoma using tumor-preferential monoclonal antibodies and F(ab')2 fragments

    SciTech Connect

    Chiou, R.K. )

    1989-12-01

    The in vivo localization of renal cell carcinoma-preferential monoclonal antibodies A6H, D5D, and C5H was evaluated and the biodistribution of F(ab')2 antibody fragments of A6H and the intact Mab were compared in over 100 nude mice. A6H localized well to most renal cell carcinoma xenografts studied; the median tumor to blood ratios ranged from 6.4 to 11.5 for various xenografts. C5H also localized well to most renal cell carcinoma xenografts tested. However, D5D did not localize well to renal cell carcinoma xenografts in vivo despite its highly restrictive in vitro reactivity. The F(ab')2 fragments of A6H produced higher tumor to blood ratios, which probably resulted from fast clearance of the fragments from the circulation. Preliminary results showed that indium-111 labeling may further improve imaging.

  8. Studies of the Inheritance of Human Ribosomal DNA Variants Detected in Two-Dimensional Separations of Genomic Restriction Fragments

    PubMed Central

    Kuick, R.; Asakawa, J. I.; Neel, J. V.; Kodaira, M.; Satoh, C.; Thoraval, D.; Gonzalez, I. L.; Hanash, S. M.

    1996-01-01

    We have investigated the variation in human ribosomal DNA repeat units as revealed in two-dimensional electrophoretic separations of genomic restriction fragments that were end-labeled at NotI cleavage sites. The transcribed portion of the ribosomal DNA results in ~20 labeled fragments visible on each gel as multicopy spots. We have mapped these spots to the sequences responsible for their appearance on the gels, based on their migration positions and direct sequencing of spots, and describe several previously unreported sources of variation. By studying mother/father/child families we gained information on how much of the between-repeats variation is due to differences between and within repeat arrays on homologous chromosomes. Two instances in which a child exhibited more copies of a particular fragment than were present in the parents are described and hypothesized to be due to events such as multiple unequal sister-chromatid exchanges or gene conversions. PMID:8878694

  9. Exclusive studies of angular distributions in GeV hadron-induced reactions with {sup 197}Au

    SciTech Connect

    Hsi, W.; Kwiatkowski, K.; Wang, G.; Bracken, D.S.; Cornell, E.; Ginger, D.S.; Viola, V.E.; Korteling, R.G.; Morley, K.B.; Huang, R.; Lynch, W.G.; Tsang, M.B.; Xi, H.; Gimeno-Nogues, F.; Ramakrishnan, E.; Rowland, D.; Yennello, S.J.; Breuer, H.; Gushue, S.; Remsberg, L.P.; Botvina, A.; Friedman, W.A.

    1999-09-01

    Exclusive studies of angular distributions for intermediate-mass fragments (IMFs) produced in GeV hadron-induced reactions have been performed with the Indiana Silicon Sphere (ISiS) 4{pi} detector array. Special emphasis has been given to understanding the origin of sideways peaking, which becomes prominent in the angular distributions for beam momenta above about 10 GeV/c. Both the magnitude of the effect and the peak angle increase as a function of fragment multiplicity and charge. When gated on IMF kinetic energy, the angular distributions evolve from forward-peaked to near isotropy as the fragment kinetic energy decreases. Fragment-fragment angular-correlation analyses show no obvious evidence for a dynamic mechanism that might signal shock wave effects or the breakup of exotic geometric shapes such as bubbles or toroids. Moving-source and intranuclear cascade simulations suggest that the observed sideways peaking is of kinematic origin, arising from significant transverse momentum imparted to the heavy recoil nucleus during the fast cascade stage of the collision. A two-step cascade and statistical multifragmentation calculation is consistent with this assumption. {copyright} {ital 1999} {ital The American Physical Society}

  10. Exclusive studies of angular distributions in GeV hadron-induced reactions with [sup 197]Au

    SciTech Connect

    Hsi, W.; Kwiatkowski, K.; Wang, G.; Bracken, D.S.; Cornell, E.; Ginger, D.S.; Viola, V.E. ); Korteling, R.G. V5A I56); Morley, K.B. ); Huang, R.; Lynch, W.G.; Tsang, M.B.; Xi, H. ); Gimeno-Nogues, F.; Ramakrishnan, E.; Rowland, D.; Yennello, S.J. ); Breuer, H. ); Gushue, S.; Remsberg, L.P. ); Botvin

    1999-09-01

    Exclusive studies of angular distributions for intermediate-mass fragments (IMFs) produced in GeV hadron-induced reactions have been performed with the Indiana Silicon Sphere (ISiS) 4[pi] detector array. Special emphasis has been given to understanding the origin of sideways peaking, which becomes prominent in the angular distributions for beam momenta above about 10 GeV/c. Both the magnitude of the effect and the peak angle increase as a function of fragment multiplicity and charge. When gated on IMF kinetic energy, the angular distributions evolve from forward-peaked to near isotropy as the fragment kinetic energy decreases. Fragment-fragment angular-correlation analyses show no obvious evidence for a dynamic mechanism that might signal shock wave effects or the breakup of exotic geometric shapes such as bubbles or toroids. Moving-source and intranuclear cascade simulations suggest that the observed sideways peaking is of kinematic origin, arising from significant transverse momentum imparted to the heavy recoil nucleus during the fast cascade stage of the collision. A two-step cascade and statistical multifragmentation calculation is consistent with this assumption. [copyright] [ital 1999] [ital The American Physical Society

  11. Electronic coupling calculation and pathway analysis of electron transfer reaction using ab initio fragment-based method. I. FMO-LCMO approach

    NASA Astrophysics Data System (ADS)

    Nishioka, Hirotaka; Ando, Koji

    2011-05-01

    By making use of an ab initio fragment-based electronic structure method, fragment molecular orbital-linear combination of MOs of the fragments (FMO-LCMO), developed by Tsuneyuki et al. [Chem. Phys. Lett. 476, 104 (2009)], 10.1016/j.cplett.2009.05.069, we propose a novel approach to describe long-distance electron transfer (ET) in large system. The FMO-LCMO method produces one-electron Hamiltonian of whole system using the output of the FMO calculation with computational cost much lower than conventional all-electron calculations. Diagonalizing the FMO-LCMO Hamiltonian matrix, the molecular orbitals (MOs) of the whole system can be described by the LCMOs. In our approach, electronic coupling TDA of ET is calculated from the energy splitting of the frontier MOs of whole system or perturbation method in terms of the FMO-LCMO Hamiltonian matrix. Moreover, taking into account only the valence MOs of the fragments, we can considerably reduce computational cost to evaluate TDA. Our approach was tested on four different kinds of model ET systems with non-covalent stacks of methane, non-covalent stacks of benzene, trans-alkanes, and alanine polypeptides as their bridge molecules, respectively. As a result, it reproduced reasonable TDA for all cases compared to the reference all-electron calculations. Furthermore, the tunneling pathway at fragment-based resolution was obtained from the tunneling current method with the FMO-LCMO Hamiltonian matrix.

  12. Electronic coupling calculation and pathway analysis of electron transfer reaction using ab initio fragment-based method. I. FMO-LCMO approach.

    PubMed

    Nishioka, Hirotaka; Ando, Koji

    2011-05-28

    By making use of an ab initio fragment-based electronic structure method, fragment molecular orbital-linear combination of MOs of the fragments (FMO-LCMO), developed by Tsuneyuki et al. [Chem. Phys. Lett. 476, 104 (2009)], we propose a novel approach to describe long-distance electron transfer (ET) in large system. The FMO-LCMO method produces one-electron Hamiltonian of whole system using the output of the FMO calculation with computational cost much lower than conventional all-electron calculations. Diagonalizing the FMO-LCMO Hamiltonian matrix, the molecular orbitals (MOs) of the whole system can be described by the LCMOs. In our approach, electronic coupling T(DA) of ET is calculated from the energy splitting of the frontier MOs of whole system or perturbation method in terms of the FMO-LCMO Hamiltonian matrix. Moreover, taking into account only the valence MOs of the fragments, we can considerably reduce computational cost to evaluate T(DA). Our approach was tested on four different kinds of model ET systems with non-covalent stacks of methane, non-covalent stacks of benzene, trans-alkanes, and alanine polypeptides as their bridge molecules, respectively. As a result, it reproduced reasonable T(DA) for all cases compared to the reference all-electron calculations. Furthermore, the tunneling pathway at fragment-based resolution was obtained from the tunneling current method with the FMO-LCMO Hamiltonian matrix.

  13. Quantification of contributions of molecular fragments for eye irritation of organic chemicals using QSAR study.

    PubMed

    Kar, Supratik; Roy, Kunal

    2014-05-01

    The eye irritation potential of chemicals has largely been evaluated using the Draize rabbit-eye test for a very long time. The Draize eye-irritation data on 38 compounds established by the European Center for Ecotoxicology and Toxicology of Chemicals (ECETOC) has been used in the present quantitative structure-activity relationship (QSAR) analysis in order to predict molar-adjusted eye scores (MES) and determine possible structural requisites and attributes that are primarily responsible for the eye irritation caused by the studied solutes. The developed model was rigorously validated internally as well as externally by applying principles of the Organization for Economic Cooperation and Development (OECD). The test for applicability domain was also carried out in order to check the reliability of the predictions. Important fragments contributing to higher MES values of the solutes were identified through critical analysis and interpretation of the developed model. Considering all the identified structural attributes, one can choose or design safe solutes with low eye irritant properties. The presented approach suggests a model for use in the context of virtual screening of relevant solute libraries. The developed QSAR model can be used to predict existing as well as future chemicals falling within the applicability domain of the model in order to reduce the use of animals. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Study of Binding Interaction between Pif80 Protein Fragment and Aragonite

    NASA Astrophysics Data System (ADS)

    Du, Yuan-Peng; Chang, Hsun-Hui; Yang, Sheng-Yu; Huang, Shing-Jong; Tsai, Yu-Ju; Huang, Joseph Jen-Tse; Chan, Jerry Chun Chung

    2016-08-01

    Pif is a crucial protein for the formation of the nacreous layer in Pinctada fucata. Three non-acidic peptide fragments of the aragonite-binding domain (Pif80) are selected, which contain multiple copies of the repeat sequence DDRK, to study the interaction between non-acidic peptides and aragonite. The polypeptides DDRKDDRKGGK (Pif80-11) and DDRKDDRKGGKDDRKDDRKGGK (Pif80-22) have similar binding affinity to aragonite. Solid-state NMR data indicate that the backbones of Pif80-11 and Pif80-22 peptides bound on aragonite adopt a random-coil conformation. Pif80-11 is a lot more effective than Pif80-22 in promoting the nucleation of aragonite on the substrate of β-chitin. Our results suggest that the structural arrangement at a protein-mineral interface depends on the surface structure of the mineral substrate and the protein sequence. The side chains of the basic residues, which function as anchors to the aragonite surface, have uniform structures. The role of basic residues as anchors in protein-mineral interaction may play an important role in biomineralization.

  15. Bacterial expression and preliminary crystallographic studies of a 149-residue fragment of human Caprin-1

    PubMed Central

    Wu, Yuhong; Zhu, Jiang; Huang, Xiaolan; Du, Zhihua

    2015-01-01

    Caprin-1 is an RNA-binding protein which plays critical roles in several important biological processes, including cellular proliferation, the interferon-mediated antiviral innate immune response, the maintenance of synaptic plasticity and the formation of RNA stress granules. Caprin-1 has been implicated in the pathogenesis of several human diseases, including osteo­sarcoma, breast cancer, viral infections, hearing loss and neurodegenerative disorders. Despite the emerging biological and physiopathological significance of Caprin-1, no structural information is available for this protein. Moreover, Caprin-1 does not have sequence similarity to any other protein with a known structure. It is therefore expected that structural studies will play a particularly crucial role in revealing the functional mechanisms of Caprin-1. Here, a protein fragment of human Caprin-1 consisting of residues 112–260 was expressed, purified and crystallized. Native and Se-SAD data sets were collected to resolutions to 2.05 and 2.65 Å, respectively, in different space groups. PMID:25760709

  16. Study of Binding Interaction between Pif80 Protein Fragment and Aragonite

    PubMed Central

    Du, Yuan-Peng; Chang, Hsun-Hui; Yang, Sheng-Yu; Huang, Shing-Jong; Tsai, Yu-Ju; Huang, Joseph Jen-Tse; Chan, Jerry Chun Chung

    2016-01-01

    Pif is a crucial protein for the formation of the nacreous layer in Pinctada fucata. Three non-acidic peptide fragments of the aragonite-binding domain (Pif80) are selected, which contain multiple copies of the repeat sequence DDRK, to study the interaction between non-acidic peptides and aragonite. The polypeptides DDRKDDRKGGK (Pif80-11) and DDRKDDRKGGKDDRKDDRKGGK (Pif80-22) have similar binding affinity to aragonite. Solid-state NMR data indicate that the backbones of Pif80-11 and Pif80-22 peptides bound on aragonite adopt a random-coil conformation. Pif80-11 is a lot more effective than Pif80-22 in promoting the nucleation of aragonite on the substrate of β-chitin. Our results suggest that the structural arrangement at a protein-mineral interface depends on the surface structure of the mineral substrate and the protein sequence. The side chains of the basic residues, which function as anchors to the aragonite surface, have uniform structures. The role of basic residues as anchors in protein-mineral interaction may play an important role in biomineralization. PMID:27484975

  17. An experimental study of hydromagmatic fragmentation through energetic, non-explosive magma-water mixing

    USGS Publications Warehouse

    Mastin, L.G.; Spieler, O.; Downey, W.S.

    2009-01-01

    In this paper we report the first experimental investigation of non-explosive hydromagmatic fragmentation during energetic mixing with water. We mix magma and water by two methods: (1) pouring a basaltic melt between two converging water sprays; and (2) jetting basaltic melt at high pressure (3??MPa) through a nozzle into a tank of stagnant water. These experiments involved shear at relative velocities of ~ 5-16??m/s and vigorous mixing for less than a second, providing sufficient time for glassy rinds to grow but insufficient time for clot interiors to cool. In resulting fragments, we examined the gross morphology, which reflects fluid deformation during mixing, and surface textures, which reflect the growth and disruption of glassy rinds. We find major differences in both fragment morphology and surface texture between experiments. Water-spray experiments produced Pele's hair, thin bubble shards, melt droplets, and angular, fracture-bound droplet pieces. Melt-jet experiments produced mostly coarse (> 1??mm diameter), wavy fluidal fragments with broken ends. Fluidal surfaces of fragments produced by water-spray experiments were generally shiny under reflected light and, in microscopic examination, smooth down to micron scale, implying no disruption of glassy rinds, except for (a) rare flaking on Pele's hair that was bent prior to solidification; or (b) cracking and alligator-skin textures on segments of melt balls that had expanded before complete cooling. In contrast, textures of fluidal surfaces on fragments produced by melt-jet experiments are dull in reflected light and, in scanning electron images, exhibit ubiquitous discontinuous skins ("rinds") that are flaked, peeled, or smeared away in stripes. Adhering to these surfaces are flakes, blocks, and blobs of detached material microns to tens of microns in diameter. In the water-spray fragments, we interpret the scarcity of disrupted surface rinds to result from lack of bending after surfaces formed. In the

  18. An experimental study of hydromagmatic fragmentation through energetic, non-explosive magma-water mixing

    NASA Astrophysics Data System (ADS)

    Mastin, L. G.; Spieler, O.; Downey, W. S.

    2009-03-01

    In this paper we report the first experimental investigation of non-explosive hydromagmatic fragmentation during energetic mixing with water. We mix magma and water by two methods: (1) pouring a basaltic melt between two converging water sprays; and (2) jetting basaltic melt at high pressure (3 MPa) through a nozzle into a tank of stagnant water. These experiments involved shear at relative velocities of ~ 5-16 m/s and vigorous mixing for less than a second, providing sufficient time for glassy rinds to grow but insufficient time for clot interiors to cool. In resulting fragments, we examined the gross morphology, which reflects fluid deformation during mixing, and surface textures, which reflect the growth and disruption of glassy rinds. We find major differences in both fragment morphology and surface texture between experiments. Water-spray experiments produced Pele's hair, thin bubble shards, melt droplets, and angular, fracture-bound droplet pieces. Melt-jet experiments produced mostly coarse (> 1 mm diameter), wavy fluidal fragments with broken ends. Fluidal surfaces of fragments produced by water-spray experiments were generally shiny under reflected light and, in microscopic examination, smooth down to micron scale, implying no disruption of glassy rinds, except for (a) rare flaking on Pele's hair that was bent prior to solidification; or (b) cracking and alligator-skin textures on segments of melt balls that had expanded before complete cooling. In contrast, textures of fluidal surfaces on fragments produced by melt-jet experiments are dull in reflected light and, in scanning electron images, exhibit ubiquitous discontinuous skins ("rinds") that are flaked, peeled, or smeared away in stripes. Adhering to these surfaces are flakes, blocks, and blobs of detached material microns to tens of microns in diameter. In the water-spray fragments, we interpret the scarcity of disrupted surface rinds to result from lack of bending after surfaces formed. In the melt

  19. A Monte Carlo study of the radiation quality dependence of DNA fragmentation spectra.

    PubMed

    Alloni, D; Campa, A; Belli, M; Esposito, G; Facoetti, A; Friedland, W; Liotta, M; Mariotti, L; Paretzke, H G; Ottolenghi, A

    2010-03-01

    We simulated the irradiation of human fibroblasts with gamma rays, protons and helium, carbon and iron ions at a fixed dose of 5 Gy. The simulations were performed with the biophysical Monte Carlo code PARTRAC. From the output of the code, containing in particular the genomic positions of the radiation-induced DNA double-strand breaks (DSBs), we obtained the DNA fragmentation spectra. Very small fragments, in particular those related to "complex lesions" (few tens of base pairs), are probably very important for the late cellular consequences, but their detection is not possible with the common experimental techniques. We paid special attention to the differences among the various ions in the production of these very small fragments; in particular, we compared the fragmentation spectra for ions of the same specific energy and for ions of the same LET (linear energy transfer). As found previously for iron ions, we found that the RBE (relative biological effectiveness) for DSB production was considerably higher than 1 for all high-LET radiations considered. This is at variance with the results obtainable from experimental data, and it is due to the ability to count the contribution of small fragments. It should be noted that for a given LET this RBE decreases with increasing ion charge, due mainly to the increasing mean energy of secondary electrons. A precise quantification of the DNA initial damage can be of great importance for both radiation protection, particularly in open-space long-term manned missions, and hadrontherapy.

  20. Laser fragmentation of foreign bodies in the urinary tract: an in vitro study and clinical application.

    PubMed

    Bedke, Jens; Kruck, Stephan; Schilling, David; Matter, Anton; Horstmann, Marcus; Sievert, Karl-Dietrich; Stenzl, Arnulf; Nagele, Udo

    2010-04-01

    Foreign bodies of the urinary tract represent a urologic emergency. First-line treatment is endoscopic removal, but this is often impeded by restricted space, especially in the urethra. We postulated that foreign objects could be fragmented by Holmium:YAG laser and investigated its effect on objects of varying composition. In a specially designed stage flushed with physiologic saline, medical and non-medical objects of differing composition and diameter were subjected to fragmentation by Holmium:YAG at powers of 18 and 30 W. In additional thermal experiments, 5,000 J was applied to differing volumes of 0.9% sodium chloride. Experiments were repeated ten times. With one exception (16 Ch silicon catheter) all medical objects were fragmented (latex urinary catheter, ureteral stents, and guidewires). Of non-medical objects (wood, steel, copper, graphite, and nylon) only copper wire was not amenable to laser dissection. These in vitro results were applied in two patients who presented with a pencil (wood and graphite) in the urethra or bladder. After Holmium:YAG laser fragmentation, the pencil could be removed by forceps each. Foreign objects in the urinary tract can be fragmented with a Holmium:YAG laser. When foreign bodies are too big for initial endoscopic extraction, the clinician should consider this technique as a reasonable and atraumatic option to avoid open surgery.

  1. Experimental studies of reactions relevant for γ-process nucleosynthesis

    SciTech Connect

    Scholz, P.; Endres, J.; Hennig, A.; Mayer, J.; Netterdon, L.; Zilges, A.; Sauerwein, A.

    2014-05-09

    We report on our recent experimental studies of reactions relevant for the γ process nucleosynthesis. Applying the activation method using the Cologne Clover Counting Setup total cross sections of the reactions {sup 168}Yb(α,γ), {sup 168}Yb(α,n), and {sup 187}Re(α,n) could be obtained. Furthermore, the reaction {sup 89}Y(p,γ) was investigated via the in-beam technique with HPGe detectors at the high-efficiency g-ray spectrometer HORUS in Cologne in order to determine partial and total cross sections.

  2. Trojan Horse Method for neutrons-induced reaction studies

    NASA Astrophysics Data System (ADS)

    Gulino, M.; Asfin Collaboration