WorldWideScience

Sample records for atomic fragment fluorescence

  1. Fluorescent amplified fragment length polymorphism (AFLP ...

    African Journals Online (AJOL)

    Rosa rugosa is an excellent ornamental plant with important ecological, economical and medicinal values in China. Polymorphism amplifications of the genomic DNA of 5 wild R. rugosa accessions and 25 cultivars that originated from China with fluorescent amplified fragment length polymorphism molecular markers were ...

  2. Computer Model Of Fragmentation Of Atomic Nuclei

    Science.gov (United States)

    Wilson, John W.; Townsend, Lawrence W.; Tripathi, Ram K.; Norbury, John W.; KHAN FERDOUS; Badavi, Francis F.

    1995-01-01

    High Charge and Energy Semiempirical Nuclear Fragmentation Model (HZEFRG1) computer program developed to be computationally efficient, user-friendly, physics-based program for generating data bases on fragmentation of atomic nuclei. Data bases generated used in calculations pertaining to such radiation-transport applications as shielding against radiation in outer space, radiation dosimetry in outer space, cancer therapy in laboratories with beams of heavy ions, and simulation studies for designing detectors for experiments in nuclear physics. Provides cross sections for production of individual elements and isotopes in breakups of high-energy heavy ions by combined nuclear and Coulomb fields of interacting nuclei. Written in ANSI FORTRAN 77.

  3. Atomic Absorption, Atomic Fluorescence, and Flame Emission Spectrometry.

    Science.gov (United States)

    Horlick, Gary

    1984-01-01

    This review is presented in six sections. Sections focus on literature related to: (1) developments in instrumentation, measurement techniques, and procedures; (2) performance studies of flames and electrothermal atomizers; (3) applications of atomic absorption spectrometry; (4) analytical comparisons; (5) atomic fluorescence spectrometry; and (6)…

  4. Quantum fluctuation effects on nuclear fragment and atomic cluster formation

    Energy Technology Data Exchange (ETDEWEB)

    Ohnishi, Akira [Hokkaido Univ., Sapporo (Japan). Dept. of Physics; Randrup, J.

    1997-05-01

    We investigate the nuclear fragmentation and atomic cluster formation by means of the recently proposed quantal Langevin treatment. It is shown that the effect of the quantal fluctuation is in the opposite direction in nuclear fragment and atomic cluster size distribution. This tendency is understood through the effective classical temperature for the observables. (author)

  5. DNA fragment sizing and sorting by laser-induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Jett, J.H.; Hammond, M.L.; Keller, R.A.; Marrone, B.L.; Martin, J.C.

    1992-12-31

    A method is provided for obtaining DNA fingerprints using high speed detection systems, such as flow cytometry to determine unique characteristics of DNA pieces from a selected sample. In one characterization the DNA piece is fragmented at preselected sites to produce a plurality of DNA fragments. The DNA piece or the resulting DNA fragments are treated with a dye effective to stain stoichiometrically the DNA fragments. The fluorescence from the dye in the stained fragments is then examined to generate an output functionally related to the number of nucleotides in each one of the DNA fragments. In one embodiment, the intensity of the fluorescence emissions from each fragment is directly proportional to the fragment length. Additional dyes can be bound to the DNA piece and DNA fragments to provide information additional to length information. Oligonucleotide specific dyes and/or hybridization probes can be bound to the DNA fragments to provide information on oligonucleotide distribution or probe hybridization to DNA fragments of different sizes.

  6. Relationships between Liquid Atomization and Solid Fragmentation

    Science.gov (United States)

    2016-03-01

    fragment size distributions found in the research literature , including specific examples of Weibull, Gamma, and root normal size distributions. This...bn 1               n m b n n m 1 1 1 The research literature usually considers Weibull size distributions to be the same when mn...approximations based on test or computational data, while those given in the grey cells are exact values derived from theory. As seen in Appendix A, the

  7. Nondestructive fluorescent state detection of single neutral atom qubits.

    Science.gov (United States)

    Gibbons, Michael J; Hamley, Christopher D; Shih, Chung-Yu; Chapman, Michael S

    2011-04-01

    We demonstrate nondestructive (lossless) fluorescent state detection of individual neutral atom qubits trapped in an optical lattice. The hyperfine state of the atom is measured with a 95% accuracy and an atom loss rate of 1%. Individual atoms are initialized and detected over 100 times before being lost from the trap, representing a 100-fold improvement in data collection rates over previous experiments. Microwave Rabi oscillations are observed with repeated measurements of one and the same single atom. © 2011 American Physical Society

  8. Fluorescent labeling of antibody fragments using split GFP.

    Directory of Open Access Journals (Sweden)

    Fortunato Ferrara

    Full Text Available Antibody fragments are easily isolated from in vitro selection systems, such as phage and yeast display. Lacking the Fc portion of the antibody, they are usually labeled using small peptide tags recognized by antibodies. In this paper we present an efficient method to fluorescently label single chain Fvs (scFvs using the split green fluorescent protein (GFP system. A 13 amino acid tag, derived from the last beta strand of GFP (termed GFP11, is fused to the C terminus of the scFv. This tag has been engineered to be non-perturbing, and we were able to show that it exerted no effect on scFv expression or functionality when compared to a scFv without the GFP11 tag. Effective functional fluorescent labeling is demonstrated in a number of different assays, including fluorescence linked immunosorbant assays, flow cytometry and yeast display. Furthermore, we were able to show that this split GFP system can be used to determine the concentration of scFv in crude samples, as well an estimate of antibody affinity, without the need for antibody purification. We anticipate this system will be of widespread interest in antibody engineering and in vitro display systems.

  9. Theory of analytical curves in atomic fluorescence flame spectrometry

    NARCIS (Netherlands)

    Hooymayers, H.P.

    An explicit expression for the intensity of atomic resonance fluorescence as a function of atomic concentration in a flame is derived under certain idealized conditions. The expression is generally valid for a pure Doppler absorption line profile as well as for a combined Doppler and collisional

  10. Resonance Fluorescence from an Artificial Atom in Squeezed Vacuum

    Directory of Open Access Journals (Sweden)

    D. M. Toyli

    2016-07-01

    Full Text Available We present an experimental realization of resonance fluorescence in squeezed vacuum. We strongly couple microwave-frequency squeezed light to a superconducting artificial atom and detect the resulting fluorescence with high resolution enabled by a broadband traveling-wave parametric amplifier. We investigate the fluorescence spectra in the weak and strong driving regimes, observing up to 3.1 dB of reduction of the fluorescence linewidth below the ordinary vacuum level and a dramatic dependence of the Mollow triplet spectrum on the relative phase of the driving and squeezed vacuum fields. Our results are in excellent agreement with predictions for spectra produced by a two-level atom in squeezed vacuum [Phys. Rev. Lett. 58, 2539 (1987], demonstrating that resonance fluorescence offers a resource-efficient means to characterize squeezing in cryogenic environments.

  11. Simultaneous single molecule atomic force and fluorescence lifetime imaging

    Science.gov (United States)

    Schulz, Olaf; Koberling, Felix; Walters, Deron; Koenig, Marcelle; Viani, Jacob; Ros, Robert

    2010-02-01

    The combination of atomic force microscopy (AFM) with single-molecule-sensitive confocal fluorescence microscopy enables a fascinating investigation into the structure, dynamics and interactions of single biomolecules or their assemblies. AFM reveals the structure of macromolecular complexes with nanometer resolution, while fluorescence can facilitate the identification of their constituent parts. In addition, nanophotonic effects, such as fluorescence quenching or enhancement due to the AFM tip, can be used to increase the optical resolution beyond the diffraction limit, thus enabling the identification of different fluorescence labels within a macromolecular complex. We present a novel setup consisting of two commercial, state-of-the-art microscopes. A sample scanning atomic force microscope is mounted onto an objective scanning confocal fluorescence lifetime microscope. The ability to move the sample and objective independently allows for precise alignment of AFM probe and laser focus with an accuracy down to a few nanometers. Time correlated single photon counting (TCSPC) gives us the opportunity to measure single-molecule fluorescence lifetimes. We will be able to study molecular complexes in the vicinity of an AFM probe on a level that has yet to be achieved. With this setup we simultaneously obtained single molecule sensitivity in the AFM topography and fluorescence lifetime imaging of YOYO-1 stained lambda-DNA samples and we showed silicon tip induced single molecule quenching on organic fluorophores.

  12. Enrichment of true positives from structural alerts through the use of novel atomic fragment based descriptors

    DEFF Research Database (Denmark)

    Long, A.; Rydberg, Patrik

    2013-01-01

    To enhance the discrimination rate for methods applying structural alerts and biotransformation rules in the prediction of toxicity and drug metabolism we have developed a set of novel fragment based atomic descriptors. These atomic descriptors encode the properties of the fragments separating...... an atom from the closest end of a branch or the molecule. The end of a branch and the end of a molecule, as well as the selection of the fragments, are made by an algorithm that uses only the distance matrix of the molecule. The novel descriptors are applied to a small set of biotransformation rules...

  13. Resonance fluorescence microscopy via three-dimensional atom localization

    Science.gov (United States)

    Panchadhyayee, Pradipta; Dutta, Bibhas Kumar; Das, Nityananda; Mahapatra, Prasanta Kumar

    2018-02-01

    A scheme is proposed to realize three-dimensional (3D) atom localization in a driven two-level atomic system via resonance fluorescence. The field arrangement for the atom localization involves the application of three mutually orthogonal standing-wave fields and an additional traveling-wave coupling field. We have shown the efficacy of such field arrangement in tuning the spatially modulated resonance in all directions. Under different parametric conditions, the 3D localization patterns originate with various shapes such as sphere, sheets, disk, bowling pin, snake flute, flower vase. High-precision localization is achieved when the radiation field detuning equals twice the combined Rabi frequencies of the standing-wave fields. Application of a traveling-wave field of suitable amplitude at optimum radiation field detuning under symmetric standing-wave configuration leads to 100% detection probability even in sub-wavelength domain. Asymmetric field configuration is also taken into consideration to exhibit atom localization with appreciable precision compared to that of the symmetric case. The momentum distribution of the localized atoms is found to follow the Heisenberg uncertainty principle under the validity of Raman-Nath approximation. The proposed field configuration is suitable for application in the study of atom localization in an optical lattice arrangement.

  14. Stabilization of 200-atom platinum nanoparticles by organosilane fragments

    KAUST Repository

    Pelzer, Katrin

    2011-04-19

    Three\\'s a charm: Platinum nanoparticles of 2 nm diameter and containing approximately 200 atoms covered with n-octylsilyl groups (see picture, right; Pt blue, Si red, C gray, H turquoise) form when [Pt(dba)2] (dba=dibenzylideneacetone) decomposes in the presence of n-octylsilane. The particles adopt a cuboctahedral structure with an edge length of three atoms. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Evidence for the Role of Proton Shell Closure in Quasifission Reactions from X-Ray Fluorescence of Mass-Identified Fragments

    Science.gov (United States)

    Morjean, M.; Hinde, D. J.; Simenel, C.; Jeung, D. Y.; Airiau, M.; Cook, K. J.; Dasgupta, M.; Drouart, A.; Jacquet, D.; Kalkal, S.; Palshetkar, C. S.; Prasad, E.; Rafferty, D.; Simpson, E. C.; Tassan-Got, L.; Vo-Phuoc, K.; Williams, E.

    2017-12-01

    The atomic numbers and the masses of fragments formed in quasifission reactions are simultaneously measured at scission in 48Ti + 238U reactions at a laboratory energy of 286 MeV. The atomic numbers are determined from measured characteristic fluorescence x rays, whereas the masses are obtained from the emission angles and times of flight of the two emerging fragments. For the first time, thanks to this full identification of the quasifission fragments on a broad angular range, the important role of the proton shell closure at Z =82 is evidenced by the associated maximum production yield, a maximum predicted by time-dependent Hartree-Fock calculations. This new experimental approach gives now access to precise studies of the time dependence of the N /Z (neutron over proton ratios of the fragments) evolution in quasifission reactions.

  16. F-RAG: Generating Atomic Coordinates from RNA Graphs by Fragment Assembly.

    Science.gov (United States)

    Jain, Swati; Schlick, Tamar

    2017-11-24

    Coarse-grained models represent attractive approaches to analyze and simulate ribonucleic acid (RNA) molecules, for example, for structure prediction and design, as they simplify the RNA structure to reduce the conformational search space. Our structure prediction protocol RAGTOP (RNA-As-Graphs Topology Prediction) represents RNA structures as tree graphs and samples graph topologies to produce candidate graphs. However, for a more detailed study and analysis, construction of atomic from coarse-grained models is required. Here we present our graph-based fragment assembly algorithm (F-RAG) to convert candidate three-dimensional (3D) tree graph models, produced by RAGTOP into atomic structures. We use our related RAG-3D utilities to partition graphs into subgraphs and search for structurally similar atomic fragments in a data set of RNA 3D structures. The fragments are edited and superimposed using common residues, full atomic models are scored using RAGTOP's knowledge-based potential, and geometries of top scoring models is optimized. To evaluate our models, we assess all-atom RMSDs and Interaction Network Fidelity (a measure of residue interactions) with respect to experimentally solved structures and compare our results to other fragment assembly programs. For a set of 50 RNA structures, we obtain atomic models with reasonable geometries and interactions, particularly good for RNAs containing junctions. Additional improvements to our protocol and databases are outlined. These results provide a good foundation for further work on RNA structure prediction and design applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Laser induced fluorescence measurements on W- and Ba atoms eroded from fluorescent lamp electrodes

    Science.gov (United States)

    Ehlbeck, J.; Rackow, K.; Sigeneger, F.; Uhrlandt, D.; Weltmann, K.-D.; Hadrath, S.; Lieder, G.

    2010-05-01

    The method of laser induced fluorescence (LIF) is applied to fluorescent lamps (FL) in order to investigate processes of electrode erosion in the vicinity of the electrodes. The life time of FLs which are ignited by instant start is mainly limited by sputtering of the coil electrodes and in final breaking. This sputtering of tungsten mainly occurs during the ignition in the glow discharge phase. Therefore, the density of W atoms is measured in the electrode region during ignition. Temporal and spatial resolved profiles were measured by LIF which has been combined with fast imaging. The life time of FLs which are started with preheated coils is also caused mainly by electrode failures. But the reason differs from the instant start case because here the loss is caused mainly by evaporation. End-of-lamp life is reached if the emitter material which is deposited at the coil to reduce the work function of the coil is lost completely. LIF is used to measure the density of the eroded emitter material, namely Barium atoms. First result of phase resolved absolute Ba atoms densities are presented.

  18. Fragmentation inside atomic cooling haloes exposed to Lyman-Werner radiation

    Science.gov (United States)

    Regan, John A.; Downes, Turlough P.

    2018-01-01

    Supermassive stars born in pristine environments in the early Universe hold the promise of being the seeds for the supermassive black holes observed as high redshift quasars shortly after the epoch of reionisation. {H_2} suppression is thought to be crucial in order to negate normal Population III star formation and allow high accretion rates to drive the formation of supermassive stars. Only in the cases where vigorous fragmentation is avoided will a monolithic collapse be successful giving rise to a single massive central object. We investigate the number of fragmentation sites formed in collapsing atomic cooling haloes subject to various levels of background Lyman-Werner flux. The background Lyman-Werner flux manipulates the chemical properties of the gas in the collapsing halo by destroying {H_2}. We find that only when the collapsing gas cloud shifts from the molecular to the atomic cooling regime is the degree of fragmentation suppressed. In our particular case we find that this occurs above a critical Lyman-Werner background of J ˜ 10 J21. The important criterion being the transition to the atomic cooling regime rather than the actual value of J, which will vary locally. Once the temperature of the gas exceeds T ≳ 104 K and the gas transitions to atomic line cooling, then vigorous fragmentation is strongly suppressed.

  19. Advanced Spectral Library (ASTRAL): Atomic Fluorescence in Cool, Evolved Stars

    Science.gov (United States)

    Carpenter, Ken G.; Nielsen, Krister E.; Kober, Gladys V.; Rau, Gioia

    2018-01-01

    The "Advanced Spectral Library (ASTRAL) Project: Cool Stars" (PI = T. Ayres) collected a definitive set of representative, high-resolution (R~46,000 in the FUV up to ~1700 Å, R~30,000 for 1700-2150 Å, and R~114,000 >2150 Å) and high signal/noise (S/N>100) UV spectra of eight F-M evolved cool stars. These extremely high-quality STIS UV echelle spectra are available from the HST archive and from the Univ. of Colorado (http://casa.colorado.edu/~ayres/ASTRAL/) and will enable investigations of a broad range of problems -- stellar, interstellar, and beyond -- for many years. In this paper, we extend our study of the very rich emission-line spectra of the four evolved K-M stars in the sample, Beta Gem (K0 IIIb), Gamma Dra (K5 III), Gamma Cru (M3.4 III), and Alpha Ori (M2 Iab), to study the atomic fluorescence processes operating in their outer atmospheres. We summarize the pumping transitions and fluorescent line products known on the basis of previous work (e.g. Carpenter 1988, etc.) and newly identified in our current, on-going analysis of these extraordinary ASTRAL STIS spectra.

  20. Atomic force microscopy imaging of fragments from the Martian meteorite ALH84001

    Science.gov (United States)

    Steele, A.; Goddard, D.; Beech, I. B.; Tapper, R. C.; Stapleton, D.; Smith, J. R.

    1998-01-01

    A combination of scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM) techniques, as well as atomic force microscopy (AFM) methods has been used to study fragments of the Martian meteorite ALH84001. Images of the same areas on the meteorite were obtained prior to and following gold/palladium coating by mapping the surface of the fragment using ESEM coupled with energy-dispersive X-ray analysis. Viewing of the fragments demonstrated the presence of structures, previously described as nanofossils by McKay et al. (Search for past life on Mars--possible relic biogenic activity in martian meteorite ALH84001. Science, 1996, pp. 924-930) of NASA who used SEM imaging of gold-coated meteorite samples. Careful imaging of the fragments revealed that the observed structures were not an artefact introduced by the coating procedure.

  1. Absolute fragmentation cross sections in atom-molecule collisions : Scaling laws for non-statistical fragmentation of polycyclic aromatic hydrocarbon molecules

    NARCIS (Netherlands)

    Chen, T.; Gatchell, M.; Stockett, M. H.; Alexander, J. D.; Zhang, Y.; Rousseau, P.; Domaracka, A.; Maclot, S.; Delaunay, R.; Adoui, L.; Huber, B. A.; Schlathölter, T.; Schmidt, H. T.; Cederquist, H.; Zettergren, H.

    2014-01-01

    We present scaling laws for absolute cross sections for non-statistical fragmentation in collisions between Polycyclic Aromatic Hydrocarbons (PAH/PAH+) and hydrogen or helium atoms with kinetic energies ranging from 50 eV to 10 keV. Further, we calculate the total fragmentation cross sections

  2. Mapping of wave packets in direct fragmentation via pump-probe frequency integrated fluorescence spectroscopy

    DEFF Research Database (Denmark)

    Engel, Volker; Henriksen, Niels Engholm

    2000-01-01

    We consider femtosecond excitation of a molecule to a dissociative electronic state. The quantum dynamics is recorded via delayed excitation to a higher electronic state and measurement of the total fluorescence from this state detected as a function of delay time. It is shown that the signal can...... be used to determine the probability density distribution of the outgoing wave packet describing the fragmentation. This, in particular, applies to the case of fragment detection since then the time-dependent signal directly measures the probability flux at a fixed value of the dissociation coordinate...

  3. Laser-induced fluorescence with an OPO system. Part II: direct determination of lead content in seawater by electrothermal atomization-laser-excited atomic fluorescence (ETA-LEAF).

    Science.gov (United States)

    Le Bihan, A; Lijour, Y; Giamarchi, P; Burel-Deschamps, L; Stephan, L

    2003-03-01

    Fluorescence was induced by coupling a laser with an optical parametric oscillator (OPO) to develop an analytical method for the direct determination of lead content, at ultra-trace level, in seawater by electrothermal atomization-laser-excited atomic fluorescence (ETA-LEAF). The optimization of atomization conditions, laser pulse energy, and mainly temporal parameters allowed us to reach a 3 fg detection limit (0.3 ng L(-1)) despite the low repetition rate of the device. The expected error on predicted concentrations of lead, at trace levels, in seawater was below 15%.

  4. Two-photon-excited fluorescence spectroscopy of atomic fluorine at 170 nm

    Science.gov (United States)

    Herring, G. C.; Dyer, Mark J.; Jusinski, Leonard E.; Bischel, William K.

    1988-01-01

    Two-photon-excited fluorescence spectroscopy of atomic fluorine is reported. A doubled dye laser at 286-nm is Raman shifted in H2 to 170 nm (sixth anti-Stokes order) to excite ground-state 2P(0)J fluorine atoms to the 2D(0)J level. The fluorine atoms are detected by one of two methods: observing the fluorescence decay to the 2PJ level or observing F(+) production through the absorption of an additional photon by the excited atoms. Relative two-photon absorption cross sections to and the radiative lifetimes of the 2D(0)J states are measured.

  5. Fragmentation of neutral carbon clusters formed by high velocity atomic collision; Fragmentation d'agregats de carbone neutres formes par collision atomique a haute vitesse

    Energy Technology Data Exchange (ETDEWEB)

    Martinet, G

    2004-05-01

    The aim of this work is to understand the fragmentation of small neutral carbon clusters formed by high velocity atomic collision on atomic gas. In this experiment, the main way of deexcitation of neutral clusters formed by electron capture with ionic species is the fragmentation. To measure the channels of fragmentation, a new detection tool based on shape analysis of current pulse delivered by semiconductor detectors has been developed. For the first time, all branching ratios of neutral carbon clusters are measured in an unambiguous way for clusters size up to 10 atoms. The measurements have been compared to a statistical model in microcanonical ensemble (Microcanonical Metropolis Monte Carlo). In this model, various structural properties of carbon clusters are required. These data have been calculated with Density Functional Theory (DFT-B3LYP) to find the geometries of the clusters and then with Coupled Clusters (CCSD(T)) formalism to obtain dissociation energies and other quantities needed to compute fragmentation calculations. The experimental branching ratios have been compared to the fragmentation model which has allowed to find an energy distribution deposited in the collision. Finally, specific cluster effect has been found namely a large population of excited states. This behaviour is completely different of the atomic carbon case for which the electron capture in the ground states predominates. (author)

  6. Rubidium atomic beam clock based on lamp-pumping and fluorescence-detection scheme

    Science.gov (United States)

    Wang, Y. H.; Huang, J. Q.; Gu, Y.; Liu, S. Q.; Dong, T. Q.; Lu, Z. H.

    2011-02-01

    A compact, portable rubidium atomic beam clock based on lamp-pumping and fluorescence-detection scheme is proposed. The expected short-term frequency stability can be at least two orders of magnitude better than previous experimental results. The usages of lamp pumping, fluorescence detection and microwave slow-wave resonance structures make this design robust and compact.

  7. Laser-excitation atomic fluorescence spectroscopy in a helium microwave-induced plasma

    Science.gov (United States)

    Schroeder, Timothy S.

    The focus of this dissertation is to report the first documented coupling of helium microwave induced plasmas (MIPs) to laser excitation atomic fluorescence spectroscopy. The ability to effectively produce intense atomic emission from both metal and nonmetal analytes gives helium microwave induced plasmas a greater flexibility than the more commonly utilized argon inductively coupled plasma (ICP). Originally designed as an element selective detector for non-aqueous chromatography applications at low applied powers (500 W). The helium MIP has been shown to be a very powerful analytical atomic spectroscopy tool. The development of the pulsed dye laser offered an improved method of excitation in the field of atomic fluorescence. The use of laser excitation for atomic fluorescence was a logical successor to the conventional excitation methods involving hollow cathode lamps and continuum sources. The highly intense, directional, and monochromatic nature of laser radiation results in an increased population of atomic species in excited electronic states where atomic fluorescence can occur. The application of laser excitation atomic fluorescence to the analysis of metals in a helium microwave induced plasma with ultrasonic sample nebulization was the initial focus of this work. Experimental conditions and results are included for the aqueous characterization of manganese, lead, thallium, and iron in the helium MIP- LEAFS system. These results are compared to previous laser excitation atomic fluorescence experimentation. The effect of matrix interferences on the analytical fluorescence signal was also investigated for each element. The advantage of helium MIPs over argon ICPs in the determination of nonmetals in solution indicates that the helium MIP is an excellent candidate for laser excitation atomic fluorescence experiments involving nonmetals such as chlorine, bromine, iodine, and sulfur. Preliminary investigations into this area are reported, including documentation

  8. Relationship between Ba atom emission and electrode temperature in a low-pressure fluorescent lamp

    Energy Technology Data Exchange (ETDEWEB)

    Yamagata, Yukihiko, E-mail: yamagata@ence.kyushu-u.ac.j [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasugakouen, Kasuga, Fukuoka 816-8580 (Japan); Kai, Makoto [Lighting Company, Panasonic Corporation, 1-1 Saiwaicho, Takatsuki, Osaka 569-1193 (Japan); Naito, Sho; Tomita, Kentaro; Uchino, Kiichiro [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasugakouen, Kasuga, Fukuoka 816-8580 (Japan); Manabe, Yoshio [Lighting Company, Panasonic Corporation, 1-1 Saiwaicho, Takatsuki, Osaka 569-1193 (Japan)

    2010-04-30

    A relationship between emission characteristics of Ba atom as an emitter material and temperature distributions of an electrode in a fluorescent lamp is described, which is measured by using laser-induced fluorescence and black-body radiation method, respectively. In a virgin lamp, a hot spot observed at the electrode edge connected to the power supply is the main source of Ba atom emission. In a long-term-used lamp, it is shown that Ba atom emission, thermionic electron emission in cathode half-cycle and electron collection in anode half-cycle are most active on the hot spot appearing on the center of the electrode.

  9. Cooperative fluorescence from a strongly driven dilute cloud of atoms

    DEFF Research Database (Denmark)

    Ott, Johan Raunkjær; Wubs, Martijn; Lodahl, Peter

    2013-01-01

    We investigate cooperative fluorescence in a dilute cloud of strongly driven two-level emitters. Starting from the Heisenberg equations of motion, we compute the first-order scattering corrections to the saturation of the excited-state population and to the resonance-fluorescence spectrum, which...... both require going beyond the state-of-the-art linear-optics approach to describe collective phenomena. A dipole blockade is observed due to long-range dipole-dipole coupling that vanishes at stronger driving fields. Furthermore, we compute the inelastic component of the light scattered by a cloud...

  10. Ultimate Statistical Physics: fluorescence of a single atom

    CERN Document Server

    Pomeau, Yves; Ginibre, Jean

    2016-01-01

    We discuss the statistics of emission of photons by a single atom or ion illuminated by a laser beam at the frequency of quasi-resonance between two energy levels, a situation that corresponds to real experiments. We extend this to the case of two laser beams resonant with the energy differences between two excited levels and the ground state (three level atom in V-configuration). We use a novel approach of this type of problem by considering Kolmogorov equation for the probability distribution of the atomic state which takes into account first the deterministic evolution of this state under the effect of the incoming laser beam and the random emission of photons during the spontaneous decay of the excited state(s) to the ground state. This approach yields solvable equations in the two level atom case. For the three level atom case we set the problem and define clearly its frame. The results obtained are valid both in the opposite limits of rare and of frequent spontaneous decay, compared to the period of the...

  11. Development and testing of hyperbaric atomic force microscopy (AFM) and fluorescence microscopy for biological applications.

    Science.gov (United States)

    D'Agostino, D P; McNally, H A; Dean, J B

    2012-05-01

    A commercially available atomic force microscopy and fluorescence microscope were installed and tested inside a custom-designed hyperbaric chamber to provide the capability to study the effects of hyperbaric gases on biological preparations, including cellular mechanism of oxidative stress. In this report, we list details of installing and testing atomic force microscopy and fluorescence microscopy inside a hyperbaric chamber. The pressure vessel was designed to accommodate a variety of imaging equipment and ensures full functionality at ambient and hyperbaric conditions (≤85 psi). Electrical, gas and fluid lines were installed to enable remote operation of instrumentation under hyperbaric conditions, and to maintain viable biological samples with gas-equilibrated superfusate and/or drugs. Systems were installed for vibration isolation and temperature regulation to maintain atomic force microscopy performance during compression and decompression. Results of atomic force microscopy testing demonstrate sub-nanometre resolution at hyperbaric pressure in dry scans and fluid scans, in both contact mode and tapping mode. Noise levels were less when measurements were taken under hyperbaric pressure with air, helium (He) and nitrogen (N(2) ). Atomic force microscopy and fluorescence microscopy measurements were made on a variety of living cell cultures exposed to hyperbaric gases (He, N(2) , O(2) , air). In summary, atomic force microscopy and fluorescence microscopy were installed and tested for use at hyperbaric pressures and enables the study of cellular and molecular effects of hyperbaric gases and pressure per se in biological preparations. © 2012 The Authors Journal of Microscopy © 2012 Royal Microscopical Society.

  12. Polymerized LB Films Imaged with a Combined Atomic Force Microscope-Fluorescence Microscope

    NARCIS (Netherlands)

    Putman, C.A.J.; Putman, Constant A.J.; Hansma, Helen G.; Gaub, Hermann E.; Hansma, Paul K.

    1992-01-01

    The first results obtained with a new stand-alone atomic force microscope (AFM) integrated with a standard Zeiss optical fluorescence microscope are presented. The optical microscope allows location and selection of objects to be imaged with the high-resolution AFM. Furthermore, the combined

  13. Laser-Induced Fluorescence Measurements for Optical Single Atom Detection for Nuclear Astrophysics

    Science.gov (United States)

    Parzuchowski, Kristen; Singh, Jaideep; Wenzl, Jennifer; Frisbie, Dustin; Johnson, Maegan

    2016-09-01

    We propose a new highly selective detector to measure rare nuclear reactions relevant for nuclear astrophysics. Our primary interest is the 22Ne(α , n) 25Mg reaction, which is a primary source of neutrons for the s-process. Our proposed detector, in conjunction with a recoil separator, captures the recoil products resulting from the reaction in a cryogenically frozen thin film of solid neon. The fluorescence spectra of the captured atoms is shifted from the absorption spectra by hundreds of nanometers. This allows for the optical detection of individual fluorescence photons against a background of intense excitation light. We will describe our initial studies of laser-induced fluorescence of Yb and Mg in solid Ne. Neon is an attractive medium because it is optically transparent and provides efficient, pure, stable, & chemically inert confinement for a wide variety of atomic and molecular species. Yb is used as a test atom because of its similar atomic structure to Mg and much brighter fluorescence signal. This work is supported by funds from Michigan State University.

  14. Observation of DNA Molecules Using Fluorescence Microscopy and Atomic Force Microscopy

    Science.gov (United States)

    Ito, Takashi

    2008-01-01

    This article describes experiments for an undergraduate instrumental analysis laboratory that aim to observe individual double-stranded DNA (dsDNA) molecules using fluorescence microscopy and atomic force microscopy (AFM). dsDNA molecules are observed under several different conditions to discuss their chemical and physical properties. In…

  15. Laser Induced Fluorescence for Singly Ionized Atomic Iodine

    Science.gov (United States)

    Steinberger, Thomas; Scime, Earl

    2017-10-01

    While xenon is the standard propellant for a wide range of plasma thrusters, xenon is expensive and xenon propellant systems require heavy compressed gas tanks, pressure regulators, and other bulky hardware. Iodine has similar mass and is much easier to acquire than xenon. Iodines natural state of matter at room temperature is solid and is easily sublimated to gas with a simple heating element. This advantage for iodine is also a significant challenge when developing gas handling systems for iodine. Another challenge for iodine thrusters is a lack of well-defined spectroscopic diagnostics for single ionized iodine, specifically, a lack of a demonstrated laser induced fluorescence (LIF) scheme. We present emission spectroscopy measurements of iodine ion emission from the 6p5P3 - 5d5D4o transition at 695.878 nm and the 6p5P3 - 6s5S2o transition at 516.12 nm as a function of pressure and microwave power for a microwave excited iodine plasma in a sealed quartz cell at a pressure of 1 mTorr. The 5d5D4o state is metastable and was identified by Hargus et al. [48th AIAA Joint Propulsion, 2012] as a strong candidate for an iodine ion LIF scheme. We will also present preliminary LIF measurements using a tunable dye laser operating at 695.878 nm. Special thanks to Dr. William Hargus Jr. and Air Force Research Laboratory at Edwards AFB.

  16. Molecular and atomic ultra trace analysis by laser induced fluorescence with OPO system and ICCD camera.

    Science.gov (United States)

    Burel, L; Giamarchi, P; Stephan, L; Lijour, Y; Le Bihan, A

    2003-06-13

    This paper presents a synthesis of some analytical potentialities of an equipment designed for both laser induced molecular and atomic fluorescence in the field of ultra-trace analysis (ng l(-1)). Excitation of fluorescence was performed with a pulsed Nd:Yag laser coupled to an optical parametric oscillator (OPO). Fluorescence spectra were recorded with a spectrograph and an intensified charge-coupled device (ICCD). The high energy and the tunability of the excitation combined with the sensitivity of the ICCD and the time-resolution provide better limit of detection (LOD) and selectivity. By molecular fluorescence, some major organic contaminants in the environment were studied, i.e. polycyclic aromatic hydrocarbons (PAHs) (benzo[a]pyrene and hydroxypyrene) and a pesticide (carbaryl). The LODs achieved by direct analysis were far below the restricted European values for tap water. Analysis was performed in water containing humic acids using time resolution to avoid the matrix fluorescence. By electro thermal atomisation-laser excited atomic fluorescence (ETA-LEAF), we detected traces of aluminium and lead in seawater. Some general considerations about the signal to noise ratio optimisation are reported. LODs reached the femtogram level.

  17. The use of fluorescent fragment length analysis (PCR-FFL) in the direct diagnosis and identification of cutaneous Leishmania species.

    Science.gov (United States)

    Tomás-Pérez, Míriam; Fisa, Roser; Riera, Cristina

    2013-03-01

    Leishmaniasis is a disease caused by different species belonging to the genus Leishmania. It presents different epidemiological and clinical features and requires the development of rapid, sensitive techniques to improve specific diagnosis. In this study, we compared the traditional technique of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with PCR-fluorescent fragment length analysis (PCR-FFL). Fluorescently tagged primers, designed in the rRNA fragment ITS-1 and 7SL region, were used to amplify fragments, which were later digested and whose sizes were accurately determined using an automated DNA sequencer. We validated the technique using 19 Leishmania strains from five cutaneous Leishmania species before testing 36 clinical samples: 23 skin biopsies and 13 skin scrapings/lesion exudates on filter paper. In real diagnostic, PCR-FFL has proved to be quick, accurate, and more sensitive (83.3% testing the ITS-1 fragment and 94.4% testing the 7SL) than PCR-RFLP analysis (75% and 80.6%). Filter papers improved the specific diagnosis in both techniques using non-invasive samples.

  18. Measurements of amplitude and frequencies of subwavelength oscillations of atoms using resonance fluorescence of three levels atom in two standing waves

    Science.gov (United States)

    Enaki, Nicolae; Bazgan, Sergiu; Mihailescu, Ion

    2015-02-01

    The resonance fluorescence of an atomic (or ion) system implanted in the materials driving two standing waves of the optical cavity is studied taking into consideration the delocalization of the atom. It is demonstrated that the resonance fluorescence depends on the position of atoms (or ions) relative the nodes or antinodes of standing waves. This situation gives us the possibility to measure the amplitude of mechanical oscillations of these radiators implanted in organic or inorganic materials. It is proposed to measure the amplitude of the mechanical oscillations relative to the equilibrium position using the time changes in the positions of the five peaks of the resonance fluorescence spectrum. In this case, the small oscillation amplitude relative to the standing wave length can drastically change the spectrum of resonance fluorescence of such atoms. The proposed method can be used in the measurements of the nanostructure temperature (or bio-molecule temperature deformation).

  19. Atomic fluorescence method for determination of concentration of alkali metal vapor using a laser source

    Energy Technology Data Exchange (ETDEWEB)

    Budkin, L.A.; Okhotnikov, O.G.; Pak, G.T.; Pikhtelev, A.I.; Puzanov, S.L.

    1984-04-01

    An experimental investigation into the temperature dependence of the cesium vapor concentration has been carried out within the 20-80 deg C temperature range on the base of the atomic fluorescence method with the use of a semiconductor laser. The relation allowing one to study the alkali metal atomic concentration as a function of the vapor temperature and also the method sensitivity as a function of the laser intensity has been derived using the balance equations. A good agreement of the experimental results with estimated ones has been obtained. The method sensitivity has been found to grow with the laser intensity.

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

    Science.gov (United States)

    Roussel, Sophie; Félix, Benjamin; Grant, Kathie; Dao, Trinh Tam; Brisabois, Anne; Amar, Corinne

    2013-01-24

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

  1. Fluorescent atom coincidence spectroscopy of extremely neutron-deficient barium isotopes

    Science.gov (United States)

    Wells, S. A.; Evans, D. E.; Griffith, J. A. R.; Eastham, D. A.; Groves, J.; Smith, J. R. H.; Tolfree, D. W. L.; Warner, D. D.; Billowes, J.; Grant, I. S.; Walker, P. M.

    1988-09-01

    Fluorescent atom coincidence spectroscopy (FACS) has been used to measure the nuclear mean square radii and moments of the extremely neutron-deficient isotopes 120-124Ba. At N=65 an abrupt change in nuclear mean square charge radii is observed which can be understood in terms of the occupation of the spin-orbit partner g7/25/2[413] neutron and g9/29/2[404] proton orbitals and the consequent enhancement of the n-p interaction.

  2. Elasticity Maps of Living Neurons Measured by Combined Fluorescence and Atomic Force Microscopy

    OpenAIRE

    Spedden, Elise; White, James D.; Naumova, Elena N.; Kaplan, David L.; Staii, Cristian

    2013-01-01

    Detailed knowledge of mechanical parameters such as cell elasticity, stiffness of the growth substrate, or traction stresses generated during axonal extensions is essential for understanding the mechanisms that control neuronal growth. Here, we combine atomic force microscopy-based force spectroscopy with fluorescence microscopy to produce systematic, high-resolution elasticity maps for three different types of live neuronal cells: cortical (embryonic rat), embryonic chick dorsal root ganglio...

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

    Directory of Open Access Journals (Sweden)

    Roussel Sophie

    2013-01-01

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

  4. Effect of Glow-to-Arc Transition on Loss Mechanism of Ba Atoms from Electrode of Fluorescent Lamp

    Science.gov (United States)

    Ueda, Takashi; Samir, Ahmed; Egashira, Yuichi; Yamashita, Go; Shimada, Shozaburo; Yamagata, Yukihiko; Uchino, Kiichiro; Manabe, Yoshio

    2007-10-01

    The loss of Ba atoms from the electrode of a fluorescent lamp was measured while the lamp was operated in the glow and arc discharge modes at 60 Hz. A laser-induced fluorescence (LIF) technique was applied to the measurements of the temporal and spatial distributions of Ba atoms in the vicinity of the electrode. Ground-state (61S0) Ba atoms were excited to a 51P1 level by a frequency-doubled dye laser beam (350.1 nm), and the subsequent fluorescence (51P1-51D2, 582.6 nm) was detected. The temporal and spatial distributions of Ba atoms were found to be completely different in the two discharge modes. Temporally; in the arc discharge mode, the density of the Ba atoms was found to have two peaks, and the number of Ba atoms emitted in the anode half-cycle was about twofold larger than that emitted in the cathode half-cycle. In the glow discharge mode, the number of Ba atoms emitted in the anode half-cycle was found to be negligible compared with that emitted in the cathode half-cycle. Spatially; in the arc discharge mode, Ba atoms were found to be emitted mainly from the hot spot of the filament electrode. In the glow discharge mode, Ba atoms were found to be emitted from all parts of the filament electrodes homogeneously. The mechanism of Ba atom loss in both modes was discussed.

  5. Influence of atomic screening on fragmentation of ultrarelativistic lead ions in LHC collimators

    DEFF Research Database (Denmark)

    Baggesen, Jan C.; Sørensen, Allan H.

    2009-01-01

    When a lead beam is collimated in the CERN LHC some of the ions fragment in the collimators causing problems downstream. For design purposes the fragmentation probability needs to be assessed. At LHC energies ( γ 3000 ; the Lorentz-factor γ is the total energy of an ion in units of its rest energ...... case for various collimator materials and find a significant effect for tungsten, the heaviest candidate planned for use....

  6. Fluorescent atom coincidence spectroscopy of extremely neutron-deficient barium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Wells, S.A.; Evans, D.E.; Griffith, J.A.R.; Eastham, D.A.; Groves, J.; Smith, J.R.H.; Tolfree, D.W.L.; Warner, D.D.; Billowes, J.; Grant, I.S.

    1988-09-01

    Fluorescent atom coincidence spectroscopy (FACS) has been used to measure the nuclear mean square radii and moments of the extremely neutron-deficient isotopes /sup 120-124/Ba. At N=65 an abrupt change in nuclear mean square charge radii is observed which can be understood in terms of the occupation of the spin-orbit partner g/sub 7/2/ 5/2(413) neutron and g/sub 9/2/ 9/2(404) proton orbitals and the consequent enhancement of the n-p interaction.

  7. Ultrastable combined atomic force and total internal reflection fluorescence microscope [corrected].

    Science.gov (United States)

    Gumpp, H; Stahl, S W; Strackharn, M; Puchner, E M; Gaub, H E

    2009-06-01

    Combining atomic force microscope (AFM) with other microscopy techniques has expanded the range of potential applications for single molecule investigations dramatically. Particularly hybrid instruments with total internal reflection fluorescence (TIRF) excitation have opened new routes in life sciences. Here we present a novel design for such a hybrid microscope, which overcomes the limitations of conventional combinations caused by their limited mechanical stability. A thorough analysis of the noise spectra and a comparison of the different designs and the different operation modes are given. With this instrument we demonstrate single molecule manipulation by AFM and simultaneous TIRF imaging.

  8. Detection of protein interactions based on GFP fragment complementation by fluorescence microscopy and spectrofluorometry

    National Research Council Canada - National Science Library

    Torrado, Mario; Iglesias, Raquel; Mikhailov, Alexander T

    2008-01-01

    ...) spectrofluorometric detection of reassembled GFP fluorescent signals directly in lysates from cell suspension thereby avoiding, in many cases, the need for tag-affinity isolation of protein complexes; and (iii...

  9. Antimony determination and speciation by multisyringe flow injection analysis with hydride generation-atomic fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Semenova, N.V. [Department of Geography, Lomonosov State University, Moscow 119899 (Russian Federation); Leal, L.O. [Department of Chemistry, University of the Balearic Islands, Carretera de Valldemossa, km.7.5, E-07122 Palma de Mallorca (Spain); Forteza, R. [Department of Chemistry, University of the Balearic Islands, Carretera de Valldemossa, km.7.5, E-07122 Palma de Mallorca (Spain); Cerda, V. [Department of Chemistry, University of the Balearic Islands, Carretera de Valldemossa, km.7.5, E-07122 Palma de Mallorca (Spain)]. E-mail: vcerda@p01.uib.es

    2005-02-07

    A new analytical procedure for determination of inorganic antimony and speciation of antimony(III) and antimony(V) is presented. For this purpose, a software-controlled time-based multisyringe flow injection system, which contains a multisyringe burette provided with a multi-port selection valve, was developed. Hydride generation-atomic fluorescence spectrometry was used as a detection technique. A 0.3% (w/v) reducing sodium tetrahydroborate solution, hydrochloric acid (2 M), an antimony solution and a pre-reducing solution of 10% (w/v) KI and 0.3% (w/v) ascorbic acid are dispensed simultaneously into a gas-liquid separation cell with further propulsion of the reaction product into the flame of an atomic fluorescence spectrometer using argon flow. A hydrogen flow was employed to support the flame. The linear range and the detection limit (3s{sub b}/S) of the proposed technique were 0.2-5.6 {mu}g l{sup -1} and 0.08 {mu}g l{sup -1}, respectively. A sample throughput of 18 samples per hour (corresponding to 80 injections per hour) was achieved. The relative standard deviation for 18 independent measurements was 4.6%. This technique was validated by means of reference solid and water materials with good agreement with the certified values. Satisfactory results for speciation of Sb(III) and Sb(V) by means of the developed technique were obtained.

  10. Backward-emitted sub-Doppler fluorescence from an optically thick atomic vapor

    Science.gov (United States)

    Carvalho, João Carlos de Aquino; Laliotis, Athanasios; Chevrollier, Martine; Oriá, Marcos; Bloch, Daniel

    2017-10-01

    Literature mentions only incidentally a sub-Doppler contribution in the excitation spectrum of the backward fluorescence of a dense vapor. This contribution is here investigated on Cs vapor, both on the first resonance line (894 nm) and on the weaker second resonance line (459 nm). We show that in a strongly absorbing medium, the quenching of excited atoms moving towards a window irradiated under near normal incidence reduces the fluorescence on the red side of the excitation spectrum. Atoms moving slowly towards the window produce a sub-Doppler velocity-selective contribution, whose visibility is here improved by applying a frequency-modulation technique. This sub-Doppler feature, induced by a surface quenching combined with a short absorption length for the incident irradiation, exhibits close analogies with the narrow spectra appearing with thin vapor cells. We also show that a normal incidence irradiation is essential for the sub-Doppler feature to be observed, while it should be independent of the detection geometry.

  11. Development of a 2D temperature measurement technique for combustion diagnostics using 2-line atomic fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Engstroem, Johan

    2001-01-01

    The present thesis is concerned with the development and application of a novel planar laser-induced fluorescence (PLIF) technique for temperature measurements in a variety of combusting flows. Accurate measurement of temperature is an essential task in combustion diagnostics, since temperature is one of the most fundamental quantities for the characterization of combustion processes. The technique is based on two-line atomic fluorescence (TLAF) from small quantities of atomic indium (In) seeded into the fuel. It has been developed from small-scale experiments in laboratory flames to the point where practical combustion systems can be studied. The technique is conceptually simple and reveals temperature information in the post-flame regions. The viability of the technique has been tested in three extreme measurement situations: in spark ignition engine combustion, in ultra-lean combustion situations such as lean burning aero-engine concepts and, finally, in fuel-rich combustion. TLAF was successfully applied in an optical Sl engine using isooctane as fuel. The wide temperature sensitivity, 700 - 3000 K, of the technique using indium atoms allowed measurements over the entire combustion cycle in the engine to be performed. In applications in lean combustion a potential problem caused by the strong oxidation processes of indium atoms was encountered. This limits measurement times due to deposits of absorbing indium oxide on measurement windows. The seeding requirement is a disadvantage of the technique and can be a limitation in some applications. The results from experiments performed in sooting flames are very promising for thermometry measurements in such environments. Absorption by hydrocarbons and other native species was found to be negligible. Since low laser energies and low seeding concentrations could be used, the technique did not, unlike most other incoherent optical thermometry techniques, suffer interferences from LII of soot particles or LIF from PAH

  12. Determination of mercury distribution inside spent compact fluorescent lamps by atomic absorption spectrometry.

    Science.gov (United States)

    Rey-Raap, Natalia; Gallardo, Antonio

    2012-05-01

    In this study, spent compact fluorescent lamps were characterized to determine the distribution of mercury. The procedure used in this research allowed mercury to be extracted in the vapor phase, from the phosphor powder, and the glass matrix. Mercury concentration in the three phases was determined by the method known as cold vapor atomic absorption spectrometry. Median values obtained in the study showed that a compact fluorescent lamp contained 24.52±0.4ppb of mercury in the vapor phase, 204.16±8.9ppb of mercury in the phosphor powder, and 18.74±0.5ppb of mercury in the glass matrix. There are differences in mercury concentration between the lamps since the year of manufacture or the hours of operation affect both mercury content and its distribution. The 85.76% of the mercury introduced into a compact fluorescent lamp becomes a component of the phosphor powder, while more than 13.66% is diffused through the glass matrix. By washing and eliminating all phosphor powder attached to the glass surface it is possible to classified the glass as a non-hazardous waste. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Correlated Fluorescence-Atomic Force Microscopy Studies of the Clathrin Mediated Endocytosis in SKMEL Cells

    Science.gov (United States)

    Smith, Steve; Hor, Amy; Luu, Anh; Kang, Lin; Scott, Brandon; Bailey, Elizabeth; Hoppe, Adam

    Clathrin-mediated endocytosis is one of the central pathways for cargo transport into cells, and plays a major role in the maintenance of cellular functions, such as intercellular signaling, nutrient intake, and turnover of plasma membrane in cells. The clathrin-mediated endocytosis process involves invagination and formation of clathrin-coated vesicles. However, the biophysical mechanisms of vesicle formation are still debated. We investigate clathrin vesicle formation mechanisms through the utilization of tapping-mode atomic force microscopy for high resolution topographical imaging in neutral buffer solution of unroofed cells exposing the inner membrane, combined with fluorescence imaging to definitively label intracellular constituents with specific fluorescent fusion proteins (actin filaments labeled with green phalloidin-antibody and clathrin coated vesicles with the fusion protein Tq2) in SKMEL (Human Melanoma) cells. Results from our work are compared against dynamical polarized total internal fluorescence (TIRF), super-resolution photo-activated localization microscopy (PALM) and transmission electron microscopy (TEM) to draw conclusions regarding the prominent model of vesicle formation in clathrin-mediated endocytosis. Funding provided by NSF MPS/DMR/BMAT award # 1206908.

  14. Reaction microscopes applied to study atomic and molecular fragmentation in intense laser fields: non-sequential double ionization of helium

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, V.L.B. de [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Rudenko, A. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Feuerstein, B. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Zrost, K. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Schroeter, C.D. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Moshammer, R. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Ullrich, J. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)]. E-mail: joachim.ullrich@mpi-hd.mpg.de

    2004-12-01

    'Reaction Microscopes' enable to detect the momentum vectors of several electrons and ions after the fragmentation of atoms or molecules. Thus, the investigation of pathways to single and multiple electron ejection in femtosecond PW/cm{sup 2} laser fields has become experimentally accessible in unprecedented detail. In this paper, a newly designed machine is described, resolutions achieved for electrons and ions are discussed and examples are given for many-particle fragmentation of atoms and molecules. Moreover, for helium, new results on single as well as first multiple differential data on double ionization are presented. Covering a wide intensity range within the 'non-sequential' (NS) double ionization regime, the importance of different NS double ionization mechanisms is explored as a function of the laser intensity. Contributions due to recollision-excitation plus subsequent field ionization (RESI) are identified and correlated electron emission spectra are discussed in the longitudinal as well as transverse directions. Whereas only weak indications of Coulomb-repulsion between the electrons in the final state are observed the emitted electrons are found to be strongly correlated with the ions.

  15. Atomic fluorescence emitted from a corona discharge in helium above and below saturated vapour pressure

    Science.gov (United States)

    Shiltagh, Nagham M.; Mendoza Luna, Luis G.; Watkins, Mark J.; Thornton, Stuart C.; von Haeften, Klaus

    2018-01-01

    A new apparatus was constructed to investigate the visible and near infrared fluorescence spectroscopy of electronically excited helium over a wide range of pressures and temperatures, covering both the gaseous and liquid phases. To achieve sufficient throughput, increased sensitivity was established by employing a micro-discharge cell and a high performance lens system that allows for a large collection solid angle. With this set-up, several thousand spectra were recorded. The atomic 3 s 1 S → 2 p 1 P and 3 s 3 S → 2 p 3 P atomic transitions showed line shifts, spectral broadening and intensity changes that were dependent in magnitude on pressure, temperature and thermodynamic phase. While in the gas phase the lines showed little dependency on the discharge cell temperature, the opposite was observed for the liquid phase, suggesting that a significant number of atoms were solvated. Triplet lines were up to a factor of 50 times stronger in intensity than the singlet lines, depending on pressure. When taking the particle density into account, this effect was stronger in the gas phase than in the liquid phase of helium. This was attributed to the recombination of He2 +, He3 + and He4 + with electrons, which is facilitated in the gas phase because of the significantly higher mobility.

  16. Strength fragmentation of Gamow-Teller transitions and delayed neutron emission of atomic nuclei

    Science.gov (United States)

    Severyukhin, A. P.

    2017-11-01

    Starting from a Skyrme interaction with tensor terms, the β-decay rates of 52Ca have been studied within a microscopic model including the 2 p - 2 h configuration effects. We observe a redistribution of the strength of Gamow-Teller transitions due to the 2 p - 2 h fragmentation. Taking into account this effect results in a satisfactory description of the neutron emission probability of the β-decay in 52Ca.

  17. Shape analysis of current pulses delivered by semiconductor detectors: A new tool for fragmentation studies of high velocity atomic clusters and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Chabot, M. E-mail: chabot@ipno.in2p3.fr; Della Negra, S.; Lavergne, L.; Martinet, G.; Wohrer-Beroff, K. E-mail: wohrer@gps.jussieu.fr; Sellem, R.; Daniel, R.; Le Bris, J.; Lalu, G.; Gardes, D.; Scarpaci, J.A.; Desesquelle, P.; Lima, V

    2002-11-01

    Shape analyses of current pulses delivered by semiconductor detectors under impact of high velocity atomic clusters have been performed for the first time. We show in this paper that the shape of the current pulse depends sensitively on the cluster size. When the cluster is fragmented, the obtained signal is found to result from the sum of signals associated with individual fragment impacts so that recognition of the fragmentation pathway is made possible in an unambiguous way. Application to the extraction of the 29 fragmentation channels of neutral C{sub 9} clusters is presented.

  18. Shape analysis of current pulses delivered by semiconductor detectors: A new tool for fragmentation studies of high velocity atomic clusters and molecules

    CERN Document Server

    Chabot, M; Lavergne, L; Martinet, G; Wohrer-Beroff, K; Sellem, R; Daniel, R; Le Bris, J; Lalu, G; Gardes, D; Scarpaci, J A; Désesquelles, P; Lima, V

    2002-01-01

    Shape analyses of current pulses delivered by semiconductor detectors under impact of high velocity atomic clusters have been performed for the first time. We show in this paper that the shape of the current pulse depends sensitively on the cluster size. When the cluster is fragmented, the obtained signal is found to result from the sum of signals associated with individual fragment impacts so that recognition of the fragmentation pathway is made possible in an unambiguous way. Application to the extraction of the 29 fragmentation channels of neutral C sub 9 clusters is presented.

  19. Projectile atomic-number effect on ion-induced fragmentation and ionization of fullerenes

    NARCIS (Netherlands)

    Hadjar, O; Hoekstra, R; Morgenstern, R; Schlatholter, T

    The delocalized pi electrons of a C-60 cluster can be well described as an electron gas. Electronic friction experienced by a multicharged ion colliding with a fullerene might then be modeled in terms of the electronic stopping power. We investigated such collisions for projectile atomic numbers Z

  20. Study on Temporal and Spatial Distributions of Ba Atoms in Fluorescent Lamp Discharge Using Laser-Induced Florescence

    Science.gov (United States)

    AlyHendy, Ahmed Samir; Yamashita, Go; Yamagata, Yukihiko; Uchino, Kiichiro; Ueda, Takashi; Manabe, Yoshio

    2006-10-01

    A laser-induced fluorescence (LIF) technique was applied to the measurements of the temporal and spatial distributions of Ba atoms in the vicinity of the electrode of a fluorescent lamp operated at 60 Hz. Ground-state (61S0) Ba atoms were excited to a 51P1 level (350.1 nm) by a frequency-doubled dye laser beam, and the subsequent fluorescence (51P1-51D2, 582.6 nm) was detected. Over a whole periodic time (16.67 ms), the density of the Ba atoms was found to have two peaks, and the number of Ba atoms emitted in the anode half-cycle was about twofold larger than that emitted in the cathode half-cycle. This difference between the Ba atoms emitted during the anode half-cycle and those emitted during the cathode half-cycle was studied for lamps with different gas pressures. Ba atoms were found to be emitted mainly from the hot spot of the filament electrode. It is suggested that the main factor for Ba atom emission from the electrode is not sputtering by ion bombardment but thermal evaporation.

  1. High-speed atomic force microscope combined with single-molecule fluorescence microscope.

    Science.gov (United States)

    Fukuda, Shingo; Uchihashi, Takayuki; Iino, Ryota; Okazaki, Yasutaka; Yoshida, Masato; Igarashi, Kiyohiko; Ando, Toshio

    2013-07-01

    High-speed atomic force microscopy (HS-AFM) and total internal reflection fluorescence microscopy (TIRFM) have mutually complementary capabilities. Here, we report techniques to combine these microscopy systems so that both microscopy capabilities can be simultaneously used in the full extent. To combine the two systems, we have developed a tip-scan type HS-AFM instrument equipped with a device by which the laser beam from the optical lever detector can track the cantilever motion in the X- and Y-directions. This stand-alone HS-AFM system is mounted on an inverted optical microscope stage with a wide-area scanner. The capability of this combined system is demonstrated by simultaneous HS-AFM∕TIRFM imaging of chitinase A moving on a chitin crystalline fiber and myosin V walking on an actin filament.

  2. Characterization of early-stage amyloid aggregates by incorporating extrinsic fluorescence and atomic force microscopy.

    Science.gov (United States)

    Koh, Moonjee; Lee, Hwiin; Lee, Youmin; Lee, Minyung

    2014-11-01

    Amyloid-β (Aβ) oligomers are nanosized bio-assemblies that cause Alzheimer's disease. Characterizing early-stage Aβ aggregates becomes an important issue because it is a prerequisite in exploring small molecule inhibitors that bind to Aβ oligomers. Of special interest are efficient screening systems that characterize the Aβ oligomer size with respect to the aging time. In this work, highly sensitive fluorescence techniques and atomic force microscopy (AFM) were employed to investigate the size determination of Aβ and screening of small molecule inhibitors. A solvatochromic dye, 1-anilinonaphthalene-8-sulfonic acid (ANS), was used as an extrinsic fluorophore to monitor the growth mechanism of the Aβ aggregates. Then, the time-resolved fluorescence anisotropy method was employed to estimate the hydrodynamic size of Aβ oligomers. Finally, AFM was used to characterize the Aβ oligomer size in the absence and presence of potential inhibitors. We present that the combination of such three experimental techniques is an excellent way to detect the early stage of Aβ aggregation and to screen small molecule inhibitors.

  3. Tunable diode-laser induced fluorescence on Al and Ti atoms in low pressure magnetron discharges

    Energy Technology Data Exchange (ETDEWEB)

    Vitelaru, C; Minea, T M; Boisse-Laporte, C; Bretagne, J [Laboratoire de Physique des Gaz et Plasmas, UMR 8578 CNRS, Universite Paris Sud-XI, 91405 Orsay Cedex (France); Aniculaesei, C; Popa, G [Physics Department, Faculty of Physics Al I Cuza University, Bd. Carol No 11, Iasi, 700506 (Romania); De Poucques, L, E-mail: catalin.vitelaru@u-psud.f [Institut Jean Lamour, CNRS - UHP Nancy, UPV-Metz, Faculte des Sciences et Techniques, boulevard des aiguillettes, BP 70239 - 54506 Vandoeuvre les Nancy Cedex (France)

    2010-03-31

    Two different blue light laser diodes were used to investigate two types of atoms, namely Ti with resonance transition centred at {lambda}{sub 0}(Ti) = 398.289 nm and Al with {lambda}{sub 0}(Al) = 394.512 nm. Tunable diode-laser induced fluorescence offers local information on two groups of sputtered particles-non-thermalized and thermalized. The anisotropic velocity distribution functions (vdfs) are characterized probing the plasma along two directions: parallel to the target, v{sub r}, and perpendicular to it, v{sub z}. Measurements were performed in two plasma reactors both having planar magnetron cathodes with circular symmetry but with Ti and Al targets of different magnet strengths and diameters. The similar results of the vdf space dependence for these magnetron systems confirm the general behaviour of sputtered species transport. These similarities are related to the circular geometry and fundamentals of sputtering whereas differences are due to each specific sputtered element. The experimental results also show the effect of current density on the shape of vdf for Ti and Al. An increase in the current intensity implies a linear increase in the relative density of energetic sputtered atoms while the group of thermalized ones appears unaffected in the high current density regime.

  4. Frustrated tunneling ionization during laser-induced D{sub 2} fragmentation: Detection of excited metastable D{sup *} atoms

    Energy Technology Data Exchange (ETDEWEB)

    McKenna, J.; Zeng, S.; Hua, J. J.; Sayler, A. M.; Zohrabi, M.; Johnson, Nora G.; Gaire, B.; Carnes, K. D.; Esry, B. D.; Ben-Itzhak, I. [J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, Kansas 66506 (United States)

    2011-10-15

    In a recent Letter, Manschwetus et al.[Phys. Rev. Lett. 102, 113002 (2009)] reported evidence of electron recapture during strong-field fragmentation of H{sub 2}--explained using a frustrated tunneling ionization model. Unusually, the signature of this process was detection of excited H{sup *} atoms. We report here an extensive study of this process in D{sub 2}. Our measurements encompass a study of the pulse duration, intensity, ellipticity, and angular distribution dependence of D{sup *} formation. While we find that the mechanism suggested by Manschwetus et al. is consistent with our experimental data, our theoretical work shows that electron recollision excitation cannot be completely ruled out as an alternative mechanism for D{sup *} production.

  5. Interaction of an anticancer peptide fragment of azurin with p53 and its isolated domains studied by atomic force spectroscopy.

    Science.gov (United States)

    Bizzarri, Anna Rita; Santini, Simona; Coppari, Emilia; Bucciantini, Monica; Di Agostino, Silvia; Yamada, Tohru; Beattie, Craig W; Cannistraro, Salvatore

    2011-01-01

    p28 is a 28-amino acid peptide fragment of the cupredoxin azurin derived from Pseudomonas aeruginosa that preferentially penetrates cancerous cells and arrests their proliferation in vitro and in vivo. Its antitumor activity reportedly arises from post-translational stabilization of the tumor suppressor p53 normally downregulated by the binding of several ubiquitin ligases. This would require p28 to specifically bind to p53 to inhibit specific ligases from initiating proteosome-mediated degradation. In this study, atomic force spectroscopy, a nanotechnological approach, was used to investigate the interaction of p28 with full-length p53 and its isolated domains at the single molecule level. Analysis of the unbinding forces and the dissociation rate constant suggest that p28 forms a stable complex with the DNA-binding domain of p53, inhibiting the binding of ubiquitin ligases other than Mdm2 to reduce proteasomal degradation of p53.

  6. Photon-number statistics from resonance fluorescence of a two-level atom near a plasmonic nanoparticle

    Science.gov (United States)

    Pastukhov, Vladimir M.; Vladimirova, Yulia V.; Zadkov, Victor N.

    2014-12-01

    The photon-number statistics from resonance fluorescence of a two-level atom near a metal nanosphere driven by a laser field with finite bandwidth is studied theoretically. Our analysis shows that all interesting physics here takes place in a small area around the nanosphere where the near field and the atom-nanosphere coupling essentially affect the radiative properties of the atom. Computer modeling estimates this area roughly as r ≤2 a (r is the distance from the center of the nanosphere to the atom), with a being the radius of the nanosphere. At the larger distances, the influence of the nanoparticle vanishes and the atom tends to behave similarly to that in free space. It is shown that the distribution function p (n ,T ) of the emission probability of n photons in a given time interval T in steady-state resonance fluorescence drastically depends on the atom location around the nanosphere for r ≤2 a , featuring a characteristic twist in the ridgelike dependence and a convergence time of up to 9 μ s, two orders of magnitude slower than for the atom in free space. At large distances, the distribution converges to a Gaussian one, as for the atom in free space. The typical convergence time scale at large distances r >2 a tends to the convergence time of the atom in free space. There are also two areas symmetrical around the nanosphere in which Ω ˜γ and the convergence time goes to zero. This behavior is determined by the interplay of the radiative and nonradiative decay rates of the atom due to the coupling with the metal nanosphere and by the near-field intensity. Additional parameters are the normalized laser frequency detuning from the atomic resonance and the bandwidth of the incoming laser field.

  7. In situ detection of atomic and molecular iodine using Resonance and Off-Resonance Fluorescence by Lamp Excitation: ROFLEX

    Science.gov (United States)

    Gómez Martín, J. C.; Blahins, J.; Gross, U.; Ingham, T.; Goddard, A.; Mahajan, A. S.; Ubelis, A.; Saiz-Lopez, A.

    2011-01-01

    We demonstrate a new instrument for in situ detection of atmospheric iodine atoms and molecules based on atomic and molecular resonance and off-resonance ultraviolet fluorescence excited by lamp emission. The instrument combines the robustness, light weight, low power consumption and efficient excitation of radio-frequency discharge light sources with the high sensitivity of the photon counting technique. Calibration of I2 fluorescence is achieved via quantitative detection of the molecule by Incoherent Broad Band Cavity-enhanced Absorption Spectroscopy. Atomic iodine fluorescence signal is calibrated by controlled broad band photolysis of known I2 concentrations in the visible spectral range at atmospheric pressure. The instrument has been optimised in laboratory experiments to reach detection limits of 1.2 pptv for I atoms and 13 pptv for I2, for S/N = 1 and 10 min of integration time. The ROFLEX system has been deployed in a field campaign in northern Spain, representing the first concurrent observation of ambient mixing ratios of iodine atoms and molecules in the 1-350 pptv range.

  8. Photo-fragmentation of lithium atoms studied with MOTReMi

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Ganjun

    2010-02-15

    Within this thesis, an experimental study of the photo double ionization (PDI) and the simultaneous ionization-excitation is performed for lithium in different initial states Li(1s{sup 2}2l) (l=s,p). The excess energy of the linearly polarized VUV-light is between 4 and 12 eV above the PDI-threshold. Three forefront technologies are combined: a magneto-optical trap (MOT) for lithium generating an ultra-cold and, by means of optical pumping, a state-prepared target; a reaction microscope (ReMi), enabling the momentum resolved detection of all reaction fragments with high-resolution and the free-electron laser in Hamburg (FLASH), providing an unprecedented brilliant photon beam at favourable time structure to access small cross sections. Close to threshold the total as well as differential PDI cross sections are observed to critically depend on the excitation level and the symmetry of the initial state. For the excited state Li (1s{sup 2}2p) the PDI dynamics strongly depends on the alignment of the 2p-orbital with respect to the VUV-light polarization and, thus, from the population of the magnetic substates (m{sub p}=0,{+-} 1). This alignment sensitivity decreases for increasing excess energy and is completely absent for ionization-excitation. Time-dependent close-coupling calculations are able to reproduce the experimental total cross sections with deviations of at most 30%. All the experimental observations can be consistently understood in terms of the long range electron correlation among the continuum electrons which gives rise to their preferential back-to-back emission. This alignment effect, which is observed here for the first time, allows controlling the PDI dynamics through a purely geometrical modification of the target initial state without changing its internal energy. (orig.)

  9. Redox speciation analysis of antimony in soil extracts by hydride generation atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Fuentes, Edwar; Pinochet, Hugo; Gregori, Ida de E-mail: idegrego@ucv.cl; Potin-Gautier, Martine

    2003-07-18

    A sensitive atomic spectrometric method for the redox speciation analysis of antimony in soils is described. The method is based on the selective generation of stibine from Sb(III) in a continuous flow system using atomic fluorescence spectrometry for detection. Sb(V) is masked by citric or oxalic acid in HCl medium. The procedure was optimized with synthetic solutions of Sb(III) and Sb(V). The effect of carboxylic acid and HCl concentration on the recovery of Sb(III) and Sb(V) species from standard solutions, and on the fluorescence signal were studied. Both species were extracted from soil with H{sub 2}O, 0.05 mol l{sup -1} EDTA and 0.25 mol l{sup -1} H{sub 2}SO{sub 4}. Since the soil samples were collected from sites impacted by copper mining activities, the effect of Cu{sup 2+} on the determination of antimony in synthetic solutions and soil extracts was studied. Cu{sup 2+} decreased the Sb(III) signal, but had no effect on the total antimony determination. Therefore, the selective determination of Sb(III) was carried out in citric acid-HCl medium, using the analyte addition technique. Total antimony in soil extracts was determined using the standard calibration technique after reducing Sb(V) to Sb(III) at room temperature with KI-ascorbic acid. The Sb(V) concentration was calculated from the difference between total antimony and Sb(III). The limits of detection (PS Analytical, Excalibur Millennium model) were 17 and 10 ng l{sup -1} for Sb(III) and total antimony, respectively, and the R.S.D. at the 0.5-{mu}g l{sup -1} level were 2.5 and 2.4%, respectively. The total antimony concentration of soils is in the mg kg{sup -1} range; the Sb recovery from the different soils by the extracting solutions was between less than 0.02% and approximately 10%. Similar recoveries were obtained using EDTA and sulfuric acid solutions. Sb(V) was found to be the main antimony species extracted from soils.

  10. Applicability of multisyringe chromatography coupled to cold-vapor atomic fluorescence spectrometry for mercury speciation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Guzman-Mar, J.L.; Hinojosa-Reyes, L. [Department of Chemistry Sciences, Universidad Autonoma de Nuevo Leon, Cd. Universitaria, Pedro de Alba s/n, C.P. 66451 San Nicolas de los Garza, Nuevo Leon (Mexico); Serra, A.M. [Department of Chemistry, University of the Balearic Islands, E-07122 Palma de Mallorca (Spain); Hernandez-Ramirez, A. [Department of Chemistry Sciences, Universidad Autonoma de Nuevo Leon, Cd. Universitaria, Pedro de Alba s/n, C.P. 66451 San Nicolas de los Garza, Nuevo Leon (Mexico); Cerda, V., E-mail: victor.cerda@uib.es [Department of Chemistry, University of the Balearic Islands, E-07122 Palma de Mallorca (Spain)

    2011-12-05

    Graphical abstract: An automatic system, based on the applicability of multisyringe chromatography (MSC) coupled to cold-vapor atomic fluorescence spectrometry (CV/AFS) detection is developed for mercury speciation. Highlights: Black-Right-Pointing-Pointer The on-line coupling of MSC to CV/AFS was developed for mercury speciation analysis. Black-Right-Pointing-Pointer The speciation of MeHg{sup +}, Hg{sup 2+} and EtHg{sup +} was achieved on a RP C18 monolithic column. Black-Right-Pointing-Pointer The hyphenated system provided higher sample throughput compared to HPLC-CV/AFS. Black-Right-Pointing-Pointer The limits of detection for mercury species were comparable or better than those reported by HPLC-CV/AFS. Black-Right-Pointing-Pointer The developed method also provided low instrumental and operational costs. - Abstract: In this paper, a novel automatic approach for the speciation of inorganic mercury (Hg{sup 2+}), methylmercury (MeHg{sup +}) and ethylmercury (EtHg{sup +}) using multisyringe chromatography (MSC) coupled to cold-vapor atomic fluorescence spectrometry (CV/AFS) was developed. For the first time, the separation of mercury species was accomplished on a RP C18 monolithic column using a multi-isocratic elution program. The elution protocol involved the use of 0.005% 2-mercapthoethanol in 240 mM ammonium acetate (pH 6)-acetonitrile (99:1, v/v), followed by 0.005% 2-mercapthoethanol in 240 mM ammonium acetate (pH 6)-acetonitrile (90:10, v/v). The eluted mercury species were then oxidized under post-column UV radiation and reduced using tin(II) chloride in an acidic medium. Subsequently, the generated mercury metal were separated from the reaction mixture and further atomized in the flame atomizer and detected by AFS. Under the optimized experimental conditions, the limits of detection (3{sigma}) were found to be 0.03, 0.11 and 0.09 {mu}g L{sup -1} for MeHg{sup +}, Hg{sup 2+} and EtHg{sup +}, respectively. The relative standard deviation (RSD, n = 6) of the

  11. Toward deformation densities for intramolecular interactions without radical reference states using the fragment, atom, localized, delocalized, and interatomic (FALDI) charge density decomposition scheme.

    Science.gov (United States)

    de Lange, Jurgens Hendrik; Cukrowski, Ignacy

    2017-05-15

    A novel approach for calculating deformation densities is presented, which enables to calculate the deformation density resulting from a change between two chemical states, typically conformers, without the need for radical fragments. The Fragment, Atom, Localized, Delocalized, and Interatomic (FALDI) charge density decomposition scheme is introduced, which is applicable to static electron densities (FALDI-ED), conformational deformation densities (FALDI-DD) as well as orthodox fragment-based deformation densities. The formation of an intramolecular NH⋅⋅⋅N interaction in protonated ethylene diamine is used as a case study where the FALDI-based conformational deformation densities (with atomic or fragment resolution) are compared with an orthodox EDA-based approach. Atomic and fragment deformation densities revealed in real-space details that (i) pointed at the origin of density changes associated with the intramolecular H-bond formation and (ii) fully support the IUPAC H-bond representation. The FALDI scheme is equally applicable to intra- and intermolecular interactions. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  12. Elasticity Maps of Living Neurons Measured by Combined Fluorescence and Atomic Force Microscopy

    CERN Document Server

    Spedden, Elise; Naumova, Elena N; Kaplan, David L; Staii, Cristian

    2013-01-01

    Detailed knowledge of mechanical parameters such as cell elasticity, stiffness of the growth substrate, or traction stresses generated during axonal extensions is essential for understanding the mechanisms that control neuronal growth. Here we combine Atomic Force Microscopy based force spectroscopy with Fluorescence Microscopy to produce systematic, high-resolution elasticity maps for three different types of live neuronal cells: cortical (embryonic rat), embryonic chick dorsal root ganglion, and P-19 (mouse embryonic carcinoma stem cells) neurons. We measure how the stiffness of neurons changes both during neurite outgrowth and upon disruption of microtubules of the cell. We find reversible local stiffening of the cell during growth, and show that the increase in local elastic modulus is primarily due to the formation of microtubules. We also report that cortical and P-19 neurons have similar elasticity maps, with elastic moduli in the range 0.1-2 kPa, with typical average values of 0.4 kPa (P-19) and 0.2 k...

  13. Atomic layer deposition to prevent metal transfer from implants: An X-ray fluorescence study

    Energy Technology Data Exchange (ETDEWEB)

    Bilo, Fabjola [INSTM and Chemistry for Technologies Laboratory, University of Brescia, via Branze, 38, 25123 Brescia (Italy); Borgese, Laura, E-mail: laura.borgese@unibs.itl [INSTM and Chemistry for Technologies Laboratory, University of Brescia, via Branze, 38, 25123 Brescia (Italy); Prost, Josef; Rauwolf, Mirjam; Turyanskaya, Anna; Wobrauschek, Peter; Kregsamer, Peter; Streli, Christina [Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna (Austria); Pazzaglia, Ugo [Dipartimento Specialità Medico Chirurgiche Sc. Radiol. e Sanità Pubblica, University of Brescia, v.le Europa, 11, 25121 Brescia (Italy); Depero, Laura E. [INSTM and Chemistry for Technologies Laboratory, University of Brescia, via Branze, 38, 25123 Brescia (Italy)

    2015-12-30

    Highlights: • Co and Cr migrate from bare alloy implant to the surrounding tissue showing a cluster distribution. • Co and Cr migrate from the TiO{sub 2} coated implant to the surrounding tissue showing a decreasing gradient distribution from the alloy surface. • TiO{sub 2} coating layers obtained by ALD on Co–Cr alloy show a barrier effect for the migration of metals. • The thicker the TiO{sub 2} layer deposited by ALD, the lower the metal migration. • The migration of metals from bare alloy toward the surrounding tissue increases with time. This effect is not detected in the coated samples. - Abstract: We show that Atomic Layer Deposition is a suitable coating technique to prevent metal diffusion from medical implants. The metal distribution in animal bone tissue with inserted bare and coated Co–Cr alloys was evaluated by means of micro X-ray fluorescence mapping. In the uncoated implant, the migration of Co and Cr particles from the bare alloy in the biological tissues is observed just after one month and the number of particles significantly increases after two months. In contrast, no metal diffusion was detected in the implant coated with TiO{sub 2}. Instead, a gradient distribution of the metals was found, from the alloy surface going into the tissue. No significant change was detected after two months of aging. As expected, the thicker is the TiO{sub 2} layer, the lower is the metal migration.

  14. Elasticity maps of living neurons measured by combined fluorescence and atomic force microscopy.

    Science.gov (United States)

    Spedden, Elise; White, James D; Naumova, Elena N; Kaplan, David L; Staii, Cristian

    2012-09-05

    Detailed knowledge of mechanical parameters such as cell elasticity, stiffness of the growth substrate, or traction stresses generated during axonal extensions is essential for understanding the mechanisms that control neuronal growth. Here, we combine atomic force microscopy-based force spectroscopy with fluorescence microscopy to produce systematic, high-resolution elasticity maps for three different types of live neuronal cells: cortical (embryonic rat), embryonic chick dorsal root ganglion, and P-19 (mouse embryonic carcinoma stem cells) neurons. We measure how the stiffness of neurons changes both during neurite outgrowth and upon disruption of microtubules of the cell. We find reversible local stiffening of the cell during growth, and show that the increase in local elastic modulus is primarily due to the formation of microtubules. We also report that cortical and P-19 neurons have similar elasticity maps, with elastic moduli in the range 0.1-2 kPa, with typical average values of 0.4 kPa (P-19) and 0.2 kPa (cortical). In contrast, dorsal root ganglion neurons are stiffer than P-19 and cortical cells, yielding elastic moduli in the range 0.1-8 kPa, with typical average values of 0.9 kPa. Finally, we report no measurable influence of substrate protein coating on cell body elasticity for the three types of neurons. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  15. Correlated fluorescence-atomic force microscopy studies of the clathrin mediated endocytosis in SKMEL cells

    Science.gov (United States)

    Hor, Amy; Luu, Anh; Kang, Lin; Scott, Brandon; Bailey, Elizabeth; Hoppe, Adam; Smith, Steve

    2017-02-01

    Clathrin-mediated endocytosis (CME) is one of the central pathways for cargo transport into cells, and plays a major role in the maintenance of cellular functions, such as intercellular signaling, nutrient intake, and turnover of plasma membrane in cells. The clathrin-mediated endocytosis process involves invagination and formation of clathrin-coated vesicles. However, the biophysical mechanisms of vesicle formation are still debated. Currently, there are two models describing membrane bending during the formation of clathrin cages: the first involves the deposition of all clathrin molecules to the plasma membrane, forming a flat lattice prior to membrane bending, whereas in the second model, membrane bending happens simultaneously as the clathrin arrives to the site to form a clathrin-coated cage. We investigate clathrin vesicle formation mechanisms through the utilization of tapping-mode atomic force microscopy for high resolution topographical imaging in neutral buffer solution of unroofed cells exposing the inner membrane, combined with fluorescence imaging to definitively label intracellular constituents with specific fluorophores (actin filaments labeled with green phalloidin and clathrin coated vesicles with the fusion protein Tq2) in SKMEL (Human Melanoma) cells. An extensive statistical survey of many hundreds of CME events, at various stages of progression, are observed via this method, allowing inferences about the dominant mechanisms active in CME in SKMEL cells. Results indicate a mixed model incorporating aspects of both the aforementioned mechanisms for CME.

  16. Fragmentation and plasmid strand breaks in pure and gold-doped DNA irradiated by beams of fast hydrogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Wyer, J A; Latimer, C J; Shah, M B; Currell, F J [Centre for Plasma Physics, IRCEP, Queen' s University Belfast, BT7 1NN (United Kingdom); Butterworth, K T; Hirst, D G [Experimental Therapeutics Research Group, School of Pharmacy, Queen' s University Belfast, BT9 7BL (United Kingdom); Montenegro, E C [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Cx. Postal 68528, Rio de Janeiro, RJ 21941-972 (Brazil)], E-mail: jeanwyer@phys.au.dk

    2009-08-07

    The results of an investigation into the damage caused to dry plasmid DNA after irradiation by fast (keV) hydrogen atoms are presented. Agarose gel electrophoresis was used to assess single and double strand break yields as a function of dose in dry DNA samples deposited on a mica substrate. Damage levels were observed to increase with beam energy. Strand break yields demonstrated a considerable dependence on sample structure and the method of sample preparation. Additionally, the effect of high-Z nanoparticles on damage levels was investigated by irradiating DNA samples containing controlled amounts of gold nanoparticles. In contrast to previous (photonic) studies, no enhancement of strand break yields was observed with the particles showing a slight radioprotective effect. A model of DNA damage as a function of dose has been constructed in terms of the probability for the creation of single and double strand breaks, per unit ion flux. This model provides quantitative conclusions about the effects of both gold nanoparticles and the different buffers used in performing the assays and, in addition, infers the proportion of multiply damaged fragments.

  17. Fluorescence detection of white-beam X-ray absorption anisotropy: towards element-sensitive projections of local atomic structure

    Science.gov (United States)

    Korecki, P.; Tolkiehn, M.; Dąbrowski, K. M.; Novikov, D. V.

    2011-01-01

    Projections of the atomic structure around Nb atoms in a LiNbO3 single crystal were obtained from a white-beam X-ray absorption anisotropy (XAA) pattern detected using Nb K fluorescence. This kind of anisotropy results from the interference of X-rays inside a sample and, owing to the short coherence length of a white beam, is visible only at small angles around interatomic directions. Consequently, the main features of the recorded XAA corresponded to distorted real-space projections of dense-packed atomic planes and atomic rows. A quantitative analysis of XAA was carried out using a wavelet transform and allowed well resolved projections of Nb atoms to be obtained up to distances of 10 Å. The signal of nearest O atoms was detected indirectly by a comparison with model calculations. The measurement of white-beam XAA using characteristic radiation indicates the possibility of obtaining element-sensitive projections of the local atomic structure in more complex samples. PMID:21997909

  18. The interaction between atoms of Au and Cu with clean Si(111) surface: a study combining synchrotron radiation grazing incidence X-ray fluorescence analysis and theoretical calculations.

    Science.gov (United States)

    de Carvalho, Hudson W P; Batista, Ana P L; Ramalho, Teodorico C; Pérez, Carlos A; Gobbi, Angelo Luiz

    2009-09-15

    In order to evaluate the interactions between Au/Cu atoms and clean Si(111) surface, we used synchrotron radiation grazing incidence X-ray fluorescence analysis and theoretical calculations. Optimized geometries and energies on different adsorption sites indicate that the binding energies at different adsorption sites are high, suggesting a strong interaction between metal atom and silicon surface. The Au atom showed higher interaction than Cu atom. The theoretical and experimental data showed good agreement.

  19. Potential of two-line atomic fluorescence for temperature imaging in turbulent indium-oxide-producing flames

    Energy Technology Data Exchange (ETDEWEB)

    Münsterjohann, Bettina; Huber, Franz J. T.; Klima, Tobias C.; Holfelder, Sandra; Engel, Sascha R. [Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Technische Thermodynamik (LTT) (Germany); Miller, Joseph D. [Aerospace Systems Directorate, Air Force Research Laboratory (United States); Meyer, Terrence R. [Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen Graduate School in Advanced Optical Technologies (SAOT) (Germany); Will, Stefan, E-mail: stefan.will@fau.de [Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Technische Thermodynamik (LTT) (Germany)

    2015-11-15

    The applicability of two-line atomic fluorescence (TLAF) for temperature imaging in an indium-based flame spray pyrolysis (FSP) process is demonstrated using a single tunable optical parametric oscillator (OPO) to generate the required excitation wavelengths consecutively. Single-shot images of the detected fluorescence signals demonstrate that the signal levels in the flame are suitable for evaluation of temperature and verify the capability and potential of the measurement technique directly during particle formation without additional indium seeding. Qualitative averaged two-dimensional temperature distributions in the FSP flame are presented, showing the influence of varying sheath gas flow rates on the resulting temperature distribution. With the addition of a second OPO and detection system, the two fluorescence signals acquired consecutively in this work could be obtained simultaneously and enable spatio-temporally resolved single-shot temperature measurements in flame synthesis processes of indium-containing nanoparticles.

  20. High sensitivity detection of protein molecules picked up on a probe of atomic force microscope based on the fluorescence detection by a total internal reflection fluorescence microscope.

    Science.gov (United States)

    Yamada, Takafumi; Afrin, Rehana; Arakawa, Hideo; Ikai, Atsushi

    2004-07-02

    We developed a method to detect and identify proteins on a probe of the atomic force microscope (AFM) with a high sensitivity. Due to a low background noise of the total internal reflection fluorescence microscope employed as a detecting system, we were able to achieve a high enough sensitivity to detect zeptomole orders of protein molecules immobilized on the tip. Several different methods to immobilize protein molecules to AFM-probes were tested, meant for a wide range of applications of this method. Furthermore, we demonstrated that different proteins were clearly distinguished by immunofluorescence microscopy on the probe using their specific antibodies.

  1. Visualization of cofilin-actin and Ras-Raf interactions by bimolecular fluorescence complementation assays using a new pair of split Venus fragments.

    Science.gov (United States)

    Ohashi, Kazumasa; Kiuchi, Tai; Shoji, Kazuyasu; Sampei, Kaori; Mizuno, Kensaku

    2012-01-01

    The bimolecular fluorescence complementation (BiFC) assay is a method for visualizing protein-protein interactions in living cells. To visualize the cofilin-actin interaction in living cells, a series of combinations of the N- and C-terminal fragments of Venus fused upstream or downstream of cofilin and actin were screened systematically. A new pair of split Venus fragments, Venus (1-210) fused upstream of cofilin and Venus (210-238) fused downstream of actin, was the most effective combination for visualizing the specific interaction between cofilin and actin in living cells. This pair of Venus fragments was also effective for detecting the active Ras-dependent interaction between H-Ras and Raf1 and the Ca(2+)-dependent interaction between calmodulin and its target M13 peptide. In vitro BiFC assays using the pair of purified BiFC probes provided the means to detect the specific interactions between cofilin and actin and between H-Ras and Raf1. In vivo and in vitro BiFC assays using the newly identified pair of Venus fragments will serve as a useful tool for measuring protein-protein interactions with high specificity and low background fluorescence and could be applied to the screening of inhibitors that block protein-protein interactions.

  2. A highly selective and ratiometric fluorescent probe for cyanide by rationally altering the susceptible H-atom.

    Science.gov (United States)

    Hao, Yuanqiang; Nguyen, Khac Hong; Zhang, Yintang; Zhang, Guan; Fan, Shengnan; Li, Fen; Guo, Chao; Lu, Yuanyuan; Song, Xiaoqing; Qu, Peng; Liu, You-Nian; Xu, Maotian

    2018-01-01

    A highly selective and ratiometric fluorescent probe for cyanide was rationally designed and synthesized. The probe comprises a fluorophore unit of naphthalimide and a CN- acceptor of methylated trifluoroacetamide group. For these previous reported trifluoroacetamide derivative-based cyanide chemosensors, the H-atom of amide adjacent to trifluoroacetyl group is susceptible to be attacked by various anions (CN- itself, F-, AcO-, et al.) and even the solvent molecule, which resulted in the bewildered reaction mechanism and poor selectivity of the assay. In this work, the susceptible H-atom of trifluoroacetamide was artfully substituted by alkyl group. Thus a highly specific fluorescent probe was developed for cyanide sensing. Upon the nucleophilic addition of cyanide anion to the carbonyl of trifluoroacetamide moiety of the probe, the ICT process of the probe was significantly enhanced and leading to a remarkable red shift in both absorption and emission spectra of the probe. This fluorescent assay showed a linear range of 1.0-80.0µM and a LOD (limit of detection) of 0.23µM. All the investigated interference have no influence on the sensing behavior of the probe toward cyanide. Moreover, by coating on TLC plate, the probe can be utilized for practical detection of trace cyanide in water samples. Copyright © 2017. Published by Elsevier B.V.

  3. Direct determination of mercury in white vinegar by matrix assisted photochemical vapor generation atomic fluorescence spectrometry detection

    Energy Technology Data Exchange (ETDEWEB)

    Liu Qingyang, E-mail: liuqingyang0807@yahoo.com.c [Beijing Center for Physical and Chemical Analysis, Beijing 100089 (China)

    2010-07-15

    This paper proposes the use of photochemical vapor generation with acetic acid as sample introduction for the direct determination of ultra-trace mercury in white vinegars by atomic fluorescence spectrometry. Under ultraviolet irradiation, the sample matrix (acetic acid) can reduce mercury ion to atomic mercury Hg{sup 0}, which is swept by argon gas into an atomic fluorescence spectrometer for subsequent analytical measurements. The effects of several factors such as the concentration of acetic acid, irradiation time, the flow rate of the carrier gas and matrix effects were discussed and optimized to give detection limits of 0.08 ng mL{sup -1} for mercury. Using the experimental conditions established during the optimization (3% v/v acetic acid, 30 s irradiation time and 20 W mercury lamp), the precision levels, expressed as relative standard deviation, were 4.6% (one day) and 7.8% (inter-day) for mercury (n = 9). Addition/recovery tests for evaluation of the accuracy were in the range of 92-98% for mercury. The method was also validated by analysis of vinegar samples without detectable amount of Hg spiked with aqueous standard reference materials (GBW(E) 080392 and GBW(E) 080393). The results were also compared with those obtained by acid digestion procedure and determination of mercury by ICP-MS. There was no significant difference between the results obtained by the two methods based on a t-test (at 95% confidence level).

  4. Laser-Excited Atomic Fluorescence and Ionization in a Graphite Furnace for the Determination of Metals and Nonmetals

    Science.gov (United States)

    Butcher, David James

    1990-01-01

    Here is reported novel instrumentation for atomic spectrometry that combined the use of a pulsed laser system as the light source and an electrothermal atomizer as the atom cell. The main goal of the research was to develop instrumentation that was more sensitive for elemental analysis than commercially available instruments and could be used to determine elements in real sample matrices. Laser excited atomic fluorescence spectrometry (LEAFS) in an electrothermal atomizer (ETA) was compared to ETA atomic absorption spectrometry (AAS) for the determination of thallium, manganese, and lead in food and agricultural standard reference materials (SRMs). Compared to ETA AAS, ETA LEAFS has a longer linear dynamic range (LDR) (5-7 orders of magnitude compared to 2-3 orders of magnitude) and higher sensitivity (10 ^{-16} to 10^{ -14} g as compared to 10^{ -13} to 10^{-11} g). Consequently, ETA LEAFS allows elemental analysis to be done over a wider range of concentrations with less dilution steps. Thallium was accurately determined in biological samples by ETA LEAFS at amounts five to one hundred times below the ETA AAS detection limit. ETA AAS and ETA LEAFS were compared for the determination of lead and manganese, and in general, the accuracies and precisions of ETA AAS were the same, with typical precisions between 3% and 6%. Fluorine was determined using laser excited molecular fluorescence spectrometry (LEMOFS) in an ETA. Molecular fluorescence from magnesium fluoride was collected, and the detection limit of 0.3 pg fluorine was two to six orders of magnitude more sensitive than other methods commonly used for the determination of fluorine. Significant interferences from ions were observed, but the sensitivity was high enough that fluorine could be determined in freeze dried urine SRMs by diluting the samples by a factor of one hundred to remove the interferences. Laser enhanced ionization (LEI) in an ETA was used for the determination of metals. For thallium, indium

  5. Molecular Organization of Various Collagen Fragments as Revealed by Atomic Force Microscopy and Diffusion-Ordered NMR Spectroscopy

    NARCIS (Netherlands)

    Stötzel, S.; Schurink, M.; Wienk, H.L.J.; Siebler, U.; Burg-Roderfeld, M.; Eckert, T.; Kulik, B.; Wechselberger, R.W.; Sewing, J.; Steinmeyer, J.; Oesser, S.; Boelens, R.; Siebert, H.-C.

    2012-01-01

    Heterogeneous mixtures of collagen fragments can be used as nutrition supplement or as key ingredients for ointments with therapeutic relevance in wound healing. Some mixtures of collagen fragments are referred to as collagen hydrolysates owing to the production process with hydrolytic enzymes.

  6. DFT Conformation and Energies of Amylose Fragments at Atomic Resolution Part I: Syn Forms of Alpha-Maltotetraose

    Science.gov (United States)

    DFT optimization studies of ninety syn '-maltotetraose (DP-4) amylose fragments have been carried out at the B3LYP/6-311++G** level of theory. The DP-4 fragments studied include V-helix, tightly bent conformations, a boat, and a 1C4 conformer. The standard hydroxymethyl rotamers (gg, gt, tg) were ...

  7. Trace elemental analysis of titanium dioxide pigments and automotive white paint fragments for forensic examination using high-energy synchrotron radiation x-ray fluorescence spectrometry.

    Science.gov (United States)

    Nishiwaki, Yoshinori; Watanabe, Seiya; Shimoda, Osamu; Saito, Yasuhiro; Nakanishi, Toshio; Terada, Yasuko; Ninomiya, Toshio; Nakai, Izumi

    2009-05-01

    High-energy synchrotron radiation x-ray fluorescence spectrometry (SR-XRF) utilizing 116 keV x-rays was used to characterize titanium dioxide pigments (rutile) and automotive white paint fragments for forensic examination. The technique allowed analysis of K lines of 9 trace elements in 18 titanium dioxide pigments (rutile), and 10 trace elements in finish coat layers of seven automotive white paint fragments. High-field strength elements (HFSE) were found to strongly reflect the origin of the titanium dioxide (TiO(2)) pigments, and could be used as effective parameters for discrimination and classification of the pigments and paint fragments. A pairwise comparison of the finish coat layers of seven automotive white paint fragments was performed. The trace elements in the finish coat layers detected by the high-energy SR-XRF were especially effective for identification. By introducing the trace element information of primer and electrocoat layers, all the automotive white paint fragments could be discriminated by this technique.

  8. Mercury in Environmental and Biological Samples Using Online Combustion with Sequential Atomic Absorption and Fluorescence Measurements: A Direct Comparison of Two Fundamental Techniques in Spectrometry

    Science.gov (United States)

    Cizdziel, James V.

    2011-01-01

    In this laboratory experiment, students quantitatively determine the concentration of an element (mercury) in an environmental or biological sample while comparing and contrasting the fundamental techniques of atomic absorption spectrometry (AAS) and atomic fluorescence spectrometry (AFS). A mercury analyzer based on sample combustion,…

  9. Single-lane single-fluor sequencing using dideoxy-labeled, heavy-atom-modified near-IR fluorescent dyes

    Science.gov (United States)

    Williams, Daryl C.; Flanagan, James H., Jr.; Legendre, Benjamin L., Jr.; Hammer, Robert P.; Soper, Steven A.

    1995-04-01

    Using a near-IR (NIR) fluorescence detection system and labels synthesized in our laboratories, electropherograms of oligonucleotides separated by capillary gel electrophoresis and detected using NIR fluorescence will be presented. The sequence of nucleotide bases was determined using a single-lane, single-dye technique. The molar concentrations of the ddNTP's used during extension reactions were varied in order to achieve a ratio of 4:2:1:0 (A:C:G:T) which allowed the identification of each terminal base via fluorescence intensity measurements. Sequencing ladders were prepared from the template, M13mp18, using standard Sanger dideoxy chain termination techniques, the modified T7 DNA polymerase, and a NIR-labeled M13 primer. The data indicated reliable sequence determination up to 300 bases with a base-calling accuracy of 90%. In order to eliminate the need for dye-labeled primers and the T7 DNA polymerase enzyme, we have developed a sequencing strategy which utilizes dye-labeled dideoxy nucleotides in a single-lane, single-fluor approach. Base-calling is accomplished by measuring the fluorescence lifetime of intramolecular heavy-atom modified dyes.

  10. Laser excited analytical atomic and ionic fluorescence in flames, furnaces and inductively coupled plasmas—I. General considerations

    Science.gov (United States)

    Omenetto, N.; Human, H. G. C.

    Several important parameters for the analytical use of laser excited fluorescence spectrometry in flames, graphite furnaces and inductively coupled plasmas are discussed in some detail. These parameters include the laser characteristics such as peak power, pulse duration, spectral bandwidth and repetition rate, the choice of the excitation line, the optical arrangement and the detection system, this last one centred on the widespread use of the boxcar averager. It is shown that, if the ultimate sensitivity is the goal to be achieved, then the choice must be the electrothermal atomization. However, even for flames and inductively coupled plasmas, excellent results are possible provided that: (i) the laser system allows complete spectral coverage in the ultraviolet: (ii) saturation of the fluorescence signal can be approached over a large sample volume; and (iii) the gated detection parameters and the laser repetition frequency are optimized with respect to each other so as to reach the maximum signal-to-noise ratio.

  11. Synchronizing atomic force microscopy force mode and fluorescence microscopy in real time for immune cell stimulation and activation studies.

    Science.gov (United States)

    Cazaux, Séverine; Sadoun, Anaïs; Biarnes-Pelicot, Martine; Martinez, Manuel; Obeid, Sameh; Bongrand, Pierre; Limozin, Laurent; Puech, Pierre-Henri

    2016-01-01

    A method is presented for combining atomic force microscopy (AFM) force mode and fluorescence microscopy in order to (a) mechanically stimulate immune cells while recording the subsequent activation under the form of calcium pulses, and (b) observe the mechanical response of a cell upon photoactivation of a small G protein, namely Rac. Using commercial set-ups and a robust signal coupling the fluorescence excitation light and the cantilever bending, the applied force and activation signals were very easily synchronized. This approach allows to control the entire mechanical history of a single cell up to its activation and response down to a few hundreds of milliseconds, and can be extended with very minimal adaptations to other cellular systems where mechanotransduction is studied, using either purely mechanical stimuli or via a surface bound specific ligand. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  12. A new technique for ultrafast velocity distribution measurements of atomic species by post-ionization laser induced fluorescent (PILIF)

    Energy Technology Data Exchange (ETDEWEB)

    Tabares, F.L.

    1992-07-01

    A new method for single shot velocity distribution measurement of metallic impurities of relevance for studies involving continuous sources, such as limiter experiments in fusion devices or sputtering experiments, based in the combination of Resonant Enhanced Multiphoton ionization (REMPI) and Laser Induced Fluorescence (LIF) is proposed. High ionization yield and good time resolution are expected according to the numerical simulation of the experiment that has been run for several atomic species. Other possible applications of REMPI to plasma edge physics and to conventional techniques for velocity distribution measurements are briefly addressed. (Author) 8 refs.

  13. Verification of cell viability at progressively higher scanning forces using a hybrid atomic force and fluorescence microscope.

    Science.gov (United States)

    Barnes, C A; O'Hagan, B M G; Howard, C V; McKerr, G

    2007-11-01

    The prudent use of the atomic force microscope as a supra-vital live cell imaging tool requires that cell viability must be determined before and after scanning. Complementary optical techniques in conjunction with the fluorescent dyes rhodamine-123 and ethidium homodimer have been used within this study to determine cell viability after increasing loads are applied in contact mode. Guideline force ranges for five commonly cultured cell lines, human squamous carcinoma (A431), fibroblast, HeLa, Potorous tridactylis (PtK2) and rat intestinal epithelial (RIE) cells are given.

  14. Photoluminescence Enhancement in Nanotextured Fluorescent SiC Passivated by Atomic Layer Deposited Al2O3 Films

    DEFF Research Database (Denmark)

    Lu, Weifang; Ou, Yiyu; Jokubavicius, Valdas

    2016-01-01

    The influence of thickness of atomic layer deposited Al2O3 films on nano-textured fluorescent 6H-SiC passivation is investigated. The passivation effect on the light emission has been characterized by photoluminescence and time-resolved photoluminescence at room temperature. The results show...... that 20nm thickness of Al2O3 layer is favorable to observe a large photoluminescence enhancement (25.9%) and long carrier lifetime (0.86ms). This is a strong indication for an interface hydrogenation that takes place during post-thermal annealing. These results show that an Al2O3 layer could serve...

  15. The generation of volatile organo-metallics compounds for on-line detection by atomic fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hill, S.J.; Ebdon, L.; Goodall, P. [Univ. of Plymouth (United Kingdom)] [and others

    1994-12-31

    Previously we have described the use of sodium tetraethylborate (NaTEB) to derivatise cadmium, in aqueous solution, to yield an efficient vapour generation system which can be interfaced to both atomic absorption and fluorescence spectrometry (AAS, AFS). This approach has now been extended to the vapour generation of lead via the tetra-ethyl lead species. The efficient generation of lead requires the use of an auxiliary oxidising agent such as hydrogen peroxide and is therefore analogous to the lead (IV) hybride system. Conventional continuous flow methods were applied to lead alkyl generation with detection via AAS using a flame heated quartz furnace as an atom cell. A rigorous comparison of the lead alkyl and conventional hydride methods was undertaken after optimization of the two chemisties using simplex procedures.

  16. Barrierless growth of precursor-free, ultrafast laser-fragmented noble metal nanoparticles by colloidal atom clusters - A kinetic in situ study.

    Science.gov (United States)

    Jendrzej, Sandra; Gökce, Bilal; Amendola, Vincenzo; Barcikowski, Stephan

    2016-02-01

    Unintended post-synthesis growth of noble metal colloids caused by excess amounts of reactants or highly reactive atom clusters represents a fundamental problem in colloidal chemistry, affecting product stability or purity. Hence, quantified kinetics could allow defining nanoparticle size determination in dependence of the time. Here, we investigate in situ the growth kinetics of ps pulsed laser-fragmented platinum nanoparticles in presence of naked atom clusters in water without any influence of reducing agents or surfactants. The nanoparticle growth is investigated for platinum covering a time scale of minutes to 50days after nanoparticle generation, it is also supplemented by results obtained from gold and palladium. Since a minimum atom cluster concentration is exceeded, a significant growth is determined by time resolved UV/Vis spectroscopy, analytical disc centrifugation, zeta potential measurement and transmission electron microscopy. We suggest a decrease of atom cluster concentration over time, since nanoparticles grow at the expense of atom clusters. The growth mechanism during early phase (<1day) of laser-synthesized colloid is kinetically modeled by rapid barrierless coalescence. The prolonged slow nanoparticle growth is kinetically modeled by a combination of coalescence and Lifshitz-Slyozov-Wagner kinetic for Ostwald ripening, validated experimentally by the temperature dependence of Pt nanoparticle size and growth quenching by Iodide anions. Copyright © 2015. Published by Elsevier Inc.

  17. Metal-binding proteins scanning and determination by combining gel electrophoresis, synchrotron radiation X-ray fluorescence and atomic spectrometry.

    Science.gov (United States)

    Verbi, F M; Arruda, S C C; Rodriguez, A P M; Pérez, C A; Arruda, M A Z

    2005-02-28

    In the present work, protein bands from in vitro embriogenic callus (Citrus sinensis L. Osbeck) were investigated using micro-synchrotron radiation X-ray fluorescence (muSR-XRF) after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) separation. Metal-binding protein quantification was done after microwave oven decomposition of gel by synchrotron radiation total reflection X-ray fluorescence (SR-TXRF), flame atomic absorption spectrometry (FAAS) and flame atomic emission spectrometry (FAES). According to the analysis of the protein bands, it is possible to observe that both 81 and ca. 14 kDa proteins present different Fe signal intensity at different positions. The analysis of 53 kDa protein, showed even more interesting results. Besides Fe, the muSR-XRF experiments indicate the presence of Ca, Cu, K and Zn. Chemical elements such as Cu, K, Fe and Zn were determined by SR-TXRF, Mg by FAAS and Na by FAES. Ca was determined by SR-TXRF and FAAS only for accuracy check. In the mineralised protein bands of 81 and around 14 kDa band, only Fe was determined (105 and 21.8 microg g(-1)). For those protein bands (86-ca. 14 kDa) were determined, Ca, K, Cu and Zn in a wide concentration range (42.4-283, 2.47-96.8, 0.91-15.9 and 3.39-29.7 microg g(-1), respectively).

  18. Synchronizing atomic force microscopy force mode and fluorescence microscopy in real time for immune cell stimulation and activation studies

    Energy Technology Data Exchange (ETDEWEB)

    Cazaux, Séverine; Sadoun, Anaïs; Biarnes-Pelicot, Martine; Martinez, Manuel; Obeid, Sameh [Aix Marseille Université, LAI UM 61, Marseille F-13288 (France); Inserm, UMR-S 1067, Marseille F-13288 (France); CNRS, UMR 7333, Marseille F-13288 (France); Bongrand, Pierre [Aix Marseille Université, LAI UM 61, Marseille F-13288 (France); Inserm, UMR-S 1067, Marseille F-13288 (France); CNRS, UMR 7333, Marseille F-13288 (France); APHM, Hôpital de la Conception, Laboratoire d’Immunologie, Marseille F-13385 (France); Limozin, Laurent [Aix Marseille Université, LAI UM 61, Marseille F-13288 (France); Inserm, UMR-S 1067, Marseille F-13288 (France); CNRS, UMR 7333, Marseille F-13288 (France); Puech, Pierre-Henri, E-mail: pierre-henri.puech@inserm.fr [Aix Marseille Université, LAI UM 61, Marseille F-13288 (France); Inserm, UMR-S 1067, Marseille F-13288 (France); CNRS, UMR 7333, Marseille F-13288 (France)

    2016-01-15

    A method is presented for combining atomic force microscopy (AFM) force mode and fluorescence microscopy in order to (a) mechanically stimulate immune cells while recording the subsequent activation under the form of calcium pulses, and (b) observe the mechanical response of a cell upon photoactivation of a small G protein, namely Rac. Using commercial set-ups and a robust signal coupling the fluorescence excitation light and the cantilever bending, the applied force and activation signals were very easily synchronized. This approach allows to control the entire mechanical history of a single cell up to its activation and response down to a few hundreds of milliseconds, and can be extended with very minimal adaptations to other cellular systems where mechanotransduction is studied, using either purely mechanical stimuli or via a surface bound specific ligand. - Highlights: • A signal coupling AFM and fluorescence microscopy was characterized for soft cantilevers. • It can be used as an intrinsic timer to synchronize images and forces. • Mechanical stimulation of single immune cells while recording calcium fluxes was detailed. • Light-induced mechanical modifications of lymphocytes using a PA-Rac protein were demonstrated. • The precautions and limitations of use of this effect were presented.

  19. [Determination of trace selenium in plants by hydride generation atomic fluorescence spectrometry with program temperature-controlled graphite digestion].

    Science.gov (United States)

    Qian, Wei; Jiang, Qian; Wang, Ru-Hai; Gong, Hua; Han, Yong

    2014-01-01

    Discussed several methods of pretreatment for the determination of selenium were discussed, and a program temperature-controlled graphite digestion method was developed to digest 5 kinds of representative standard plant samples of citrus leaves, tea, cabbage leaves, shrubs and rice. The effect of the pretreatment method of digestion solution, digestion temperature and digestion time on the extraction of selenium was investigated in detail. The instrumental working parameters were optimized. For the reaction conditions of hydride generation atomic fluorescence spectrometry (HG-AFS), the effect of the concentration of KBH4 and HCl on the determination of selenium was emphasized. Not only the effect of the concentration of carrier flow HCl was considered, but also the effect of the concentration of sample HCl on the determination of selenium was studied. The best method for determination of trace selenium in plant samples by atomic fluorescence spectrometry with program temperature-controlled graphite digestion was established. Results indicated that the recovery of the method of selenium was 87.1% - 106.2%, the detection limit was 0.018 microg x L(-1) and the relative standard deviation (RSD) was less than 6.0%. In the range of 0-10 microg x L(-1) (low standard) and 0-100 microg x L(-1) (high standard) fluorescence was linearly related to the concentration of selenium, the coefficient of r was 0.9999 and r was 0.9997. Therefore, this method has wide linear range, high sensitivity, low detection limit and good stability, which was very suitable for the determination of trace selenium of plant. And the method was of easy and safe operation, strong practicability, low cost, and low toxicity of chemicals used, so it can be used as a routine analysis method in general laboratory.

  20. DFT studies of the conformation and relative energies of alpha-maltotetraose (DP-4): An amylose fragment at atomic resolution

    Science.gov (United States)

    DFT optimization studies of more than one hundred conformations of a-maltotetraose have been carried out at the B3LYP/6-311++G** level of theory. The DP-4 fragments of predominately 4C1 chair residues include tightly bent forms, helix, band-flips, kinks, boat, and some 1C4 conformers. The three do...

  1. Two-Photon Laser-Induced Fluorescence O and N Atoms for the Study of Heterogeneous Catalysis in a Diffusion Reactor

    Science.gov (United States)

    Pallix, Joan B.; Copeland, Richard A.; Arnold, James O. (Technical Monitor)

    1995-01-01

    Advanced laser-based diagnostics have been developed to examine catalytic effects and atom/surface interactions on thermal protection materials. This study establishes the feasibility of using laser-induced fluorescence for detection of O and N atom loss in a diffusion tube to measure surface catalytic activity. The experimental apparatus is versatile in that it allows fluorescence detection to be used for measuring species selective recombination coefficients as well as diffusion tube and microwave discharge diagnostics. Many of the potential sources of error in measuring atom recombination coefficients by this method have been identified and taken into account. These include scattered light, detector saturation, sample surface cleanliness, reactor design, gas pressure and composition, and selectivity of the laser probe. Recombination coefficients and their associated errors are reported for N and O atoms on a quartz surface at room temperature.

  2. Determination of mercury by electrochemical cold vapor generation atomic fluorescence spectrometry using polyaniline modified graphite electrode as cathode

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Xianjuan [Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Gan Wuer, E-mail: wgan@ustc.edu.c [Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wan Lingzhong; Zhang Hanchang; He Youzhao [Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2010-02-15

    An electrochemical cold vapor generation system with polyaniline modified graphite electrode as cathode material was developed for Hg (II) determination by coupling with atomic fluorescence spectrometry. This electrochemical cold vapor generation system with polyaniline/graphite electrode exhibited higher sensitivity; excellent stability and lower memory effect compared with graphite electrode electrochemical cold vapor generation system. The relative standard deviation was 2.7% for eleven consecutive measurements of 2 ng mL{sup -1} Hg (II) standard solution and the mercury limit of detection for the sample blank solution was 1.3 rg mL{sup -1} (3sigma). The accuracy of the method was evaluated through analysis of the reference materials (GBW09101) (Human hair) and GBW (08517) (Laminaria Japonica Aresch) and the proposed method was successfully applied to the analysis of human hairs.

  3. Application of fluorescent amplified fragment length polymorphism for comparison of human and animal isolates of Yersinia enterocolitica

    DEFF Research Database (Denmark)

    Fearnley, C.; On, S.L.W.; Kokotovic, Branko

    2005-01-01

    An amplified fragment length polymorphism (AFLP) method, developed to genotype Yersinia enterocolitica, has been used to investigate 70 representative strains isolated from humans, pigs, sheep, and cattle in the United Kingdom. AFLP primarily distinguished Y enterocolitica strains according...... of serotype. However, AFLP profiles also allowed differentiation of strains within these serotype-related subclusters, indicating the high discriminatory power of the technique for Y. enterocolitica. Investigation of the relationship between strain AFLP profile and host confirmed that pigs are, and provides...

  4. Ultra-trace determination of methylmercuy in seafood by atomic fluorescence spectrometry coupled with electrochemical cold vapor generation

    Energy Technology Data Exchange (ETDEWEB)

    Zu, Wenchuan, E-mail: zuhongshuai@126.com [Beijing Institute of Technology, College of Chemistry, Beijing 100081 (China); Beijing Center for Physical & Chemical Analysis, Beijing 100089 (China); Wang, Zhenghao [Beijing Normal University, College of Chemistry, Beijing 100875 (China)

    2016-03-05

    Highlights: • Methylmercury detection by ECVG-AFS without pre-separation by HPLC is proposed. • Methylmercury is atomized by direct electrochemical reduction with no reductant. • Remarkably better sensitivity is obtained than the traditional HPLC-UV-AFS method. • Glassy carbon is the best cathode material to generate Hg vapor from methylmercury. - Abstract: A homemade electrochemical flow cell was adopted for the determination of methylmercury. The cold vapor of mercury atoms was generated from the surface of glassycarbon cathode through the method of electrolytic reduction and detected by atomic fluorescence spectroscopy subsequently. The operating conditions were optimized with 2 ng mL{sup −1} methylmercury standard solution. The caliberation curve was favorably linear when the concentrations of standard HgCH{sub 3}{sup +} solutions were in the range of 0.2–5 ng mL{sup −1}(as Hg). Under the optimized conditions, the limit of detection (LOD) for methylmercury was 1.88 × 10{sup −3} ng mL{sup −1} and the precision evaluated by relative standard deviation was 2.0% for six times 2 ng mL{sup −1} standard solution replicates. The terminal analytical results of seafood samples, available from local market, showed that the methylmercury content ranged within 3.7–45.8 ng g{sup −1}. The recoveries for methylmercury spiked samples were found to be in the range of 87.6–103.6% and the relative standard deviations below 5% (n = 6)were acquired, which showed this method was feasible for real sample analysis.

  5. Rocket observation of atomic oxygen and night airglow: Measurement of concentration with an improved resonance fluorescence technique

    Directory of Open Access Journals (Sweden)

    K. Kita

    1996-02-01

    Full Text Available An improved resonant fluorescence instrument for measuring atomic oxygen concentration was developed to avoid the Doppler effect and the aerodynamic shock effect due to the supersonic motion of a rocket. The shock effect is reduced by adopting a sharp wedge-shaped housing and by scanning of the detector field of view to change the distance between the scattering volume and the surface of the housing. The scanning enables us to determine absolute values of atomic oxygen concentration from relative variation of the scattered light signal due to the self-absorption. The instrument was calibrated in the laboratory, and the numerical simulation reproduced the calibration result. Using the instrument, the altitude profile of atomic oxygen concentration was observed by a rocket experiment at Uchinoura (31°N on 28 January 1992. The data obtained from the rocket experiment were not perfectly free from the shock effect, but errors due to the effect were reduced by the data analysis procedure. The observed maximum concentration was 3.8× 1011 cm–3 at altitudes around 94 km. The systematic error is estimated to be less than ±0.7×1011 cm–3 and the relative random error is less than±0.07× 1011 cm–3at the same altitudes. The altitude profile of the OI 557.7-nm airglow was also observed in the same rocket experiment. The maximum volume emission rate was found to be 150 photons cm–3 s–1 at 94 km. The observed altitude profiles are compared with the MSIS model and other in situ observations.

  6. Ambient-temperature trap/release of arsenic by dielectric barrier discharge and its application to ultratrace arsenic determination in surface water followed by atomic fluorescence spectrometry

    Science.gov (United States)

    A novel dielectric barrier discharge reactor (DBDR) was utilized to trap/release arsenic coupled to hydride generation atomic fluorescence spectrometry (HGAFS). On the DBD principle, the precise and accurate control of trap/release procedures was fulfilled at ambient temperature, and an analytical m...

  7. An expression for the atomic fluorescence and thermal-emission intensity under conditions of near saturation and arbitrary self-absorption

    NARCIS (Netherlands)

    Omenetto, N.; Winefordner, J.D.; Alkemade, C.T.J.

    An expression for the effect of self-absorption on the fluorescence and thermal emission intensities is derived by taking into account stimulated emission. A simple, idealized case is considered, consisting of a two level atomic system, in a flame, homogeneous with respect to temperature and

  8. Fragments analysis of Marajoara pubic covers using a portable system of X-ray fluorescence and multivariate statistics

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Renato [Instituto Federal de Educacao, Ciencia e Tecnologia do Rio de Janeiro (CPAR/IFRJ), RJ (Brazil). Curso de Licenciatura em Matematica; Calza, Cristiane Ferreira; Lopes, Ricardo Tadeu [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), RJ (Brazil); Rabello, Angela; Lima, Tania [Museu Nacional (MN/UFRJ), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    Full text: In this work it was characterized the elemental composition of 102 fragments of Marajoara pubic covers, belonging to the National Museum collection, using EDXRF and multivariate statistics analysis. The objective was to identify possible groups of samples that presented similar characteristics. This information will be useful in the development of a systematic classification of these artifacts. Provenance studies of ancient ceramics are based on the assumption that pottery produced from a specific clay will present a similar chemical composition, which will distinguish them from pottery produced from a different clay. In this way, the pottery is assigned to particular production groups, which are then correlated with their respective origins. EDXRF measurements were carried out with a portable system, developed in the Nuclear Instrumentation Laboratory, consisting of an X-ray tube Oxford TF3005 with tungsten (W) anode, operating at 25 kV and 100 {mu}A, and a Si-PIN XR-100CR detector from Amptek. In each one of the 102 fragments, six points were analyzed (three in the front part and three in the reverse) with an acquisition time of 600 s and a beam collimation of 2 mm. The spectra were processed and analyzed using the software QXAS-AXIL from IAEA. PCA was applied to the XRF results revealing a clear cluster separation to the samples. (author)

  9. Speciation analysis of arsenic compounds in seafood by ion chromatography-atomic fluorescence spectrometry

    Science.gov (United States)

    Han, Tingting; Ji, Hongwei; Li, Huixin; Cui, He; Song, Tian; Duan, Xiaojuan; Zhu, Qianlin; Cai, Feng; Zhang, Li

    2017-06-01

    Ion chromatography-ultra violet-hydride generation-Atomic Florescence Spectrometry was applied to detect 5 arsenic species in seafoods. The arsenic species studied include arsenobetaine (AsB), arsenite (As(III)), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), and arsenate (As(V)), which were extracted from samples using 2% formic acid. Gradient elution using 33 mmol L-1 CH3COONH4 and 15 mmol L-1 Na2CO3 with 10 mL CH3CH2OH at pH 8.4 allowed the chromatographic separation of all the species on a Hamilton PRP-X100 anion-exchange column in less than 8 min. In this study, an ultrasound extraction method was used to extract arsenic species from seafood. The extraction efficiency was good and the recoveries from spiked samples were in the range of 72.6%-109%; the precision between sample replicates was higher than 3.6% for all determinations. The detection limits were 3.543 μg L-1 for AsB, 0.426 μg L-1 for As(III), 0.216 μg L-1 for DMA, 0.211 μg L-1 for MMA, and 0.709 μg L-1 for As(V), and the linear coefficients were greater than 0.999. We also developed an application of this method for the determination of arsenic species in bonito, Euphausia superba, and Enteromorpha with satisfactory results. Therefore, it was confirmed that this method was appropriate for the detection of arsenic species in seafood.

  10. Relationship between cell stiffness and stress fiber amount, assessed by simultaneous atomic force microscopy and live-cell fluorescence imaging.

    Science.gov (United States)

    Gavara, Núria; Chadwick, Richard S

    2016-06-01

    Actomyosin stress fibers, one of the main components of the cell's cytoskeleton, provide mechanical stability to adherent cells by applying and transmitting tensile forces onto the extracellular matrix (ECM) at the sites of cell-ECM adhesion. While it is widely accepted that changes in spatial and temporal distribution of stress fibers affect the cell's mechanical properties, there is no quantitative knowledge on how stress fiber amount and organization directly modulate cell stiffness. We address this key open question by combining atomic force microscopy with simultaneous fluorescence imaging of living cells, and combine for the first time reliable quantitative parameters obtained from both techniques. We show that the amount of myosin and (to a lesser extent) actin assembled in stress fibers directly modulates cell stiffness in adherent mouse fibroblasts (NIH3T3). In addition, the spatial distribution of stress fibers has a second-order modulatory effect. In particular, the presence of either fibers located in the cell periphery, aligned fibers or thicker fibers gives rise to reinforced cell stiffness. Our results provide basic and significant information that will help design optimal protocols to regulate the mechanical properties of adherent cells via pharmacological interventions that alter stress fiber assembly or via micropatterning techniques that restrict stress fiber spatial organization.

  11. Antimony speciation analysis in sediment reference materials using high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Potin-Gautier, M. [Laboratoire de Chimie Analytique, BioInorganique et Environnement LCABIE (UMR CNRS 3054), Universite de Pau et des pays de l' Adour, 64000 Pau (France); Pannier, F. [Laboratoire de Chimie Analytique, BioInorganique et Environnement LCABIE (UMR CNRS 3054), Universite de Pau et des pays de l' Adour, 64000 Pau (France)]. E-mail: Florence.pannier@univ-pau.fr; Quiroz, W. [Laboratoire de Chimie Analytique, BioInorganique et Environnement LCABIE (UMR CNRS 3054), Universite de Pau et des pays de l' Adour, 64000 Pau (France); Laboratorio de Quimica Analitica y Ambiental, Instituto de Quimica, Pontificia Universidad catolica de Valparaiso (Chile); Pinochet, H. [Laboratorio de Quimica Analitica y Ambiental, Instituto de Quimica, Pontificia Universidad catolica de Valparaiso (Chile); Gregori, I. de [Laboratorio de Quimica Analitica y Ambiental, Instituto de Quimica, Pontificia Universidad catolica de Valparaiso (Chile)

    2005-11-30

    This work presents the development of suitable methodologies for determination of the speciation of antimony in sediment reference samples. Liquid chromatography with a post-column photo-oxidation step and hydride generation atomic fluorescence spectrometry as detection system is applied to the separation and determination of Sb(III), Sb(V) and trimethylantimony species. Post-column decomposition and hydride generation steps were studied for sensitive detection with the AFS detector. This method was applied to investigate the conditions under which speciation analysis of antimony in sediment samples can be carried out. Stability studies of Sb species during the extraction processes of solid matrices, using different reagents solutions, were performed. Results demonstrate that for the extraction yield and the stability of Sb species in different marine sediment extracts, citric acid in ascorbic acid medium was the best extracting solution for antimony speciation analysis in this matrix (between 55% and 65% of total Sb was recovered from CRMs, Sb(III) being the predominant species). The developed method allows the separation of the three compounds within 6 min with detection limits of 30 ng g{sup -1} for Sb(III) and TMSbCl2 and 40 ng g{sup -1} for Sb(V) in sediment samples.

  12. Determination of selenium in nutritional supplements and shampoos by flow injection-hydride generation-atomic fluorescence spectrometry.

    Science.gov (United States)

    Gámiz-Gracia, L; Luque de Castro, M D

    1999-11-15

    A method for the determination of Se in pharmaceutical samples (nutritional supplements and shampoos) is proposed. The method involves two steps: (1) digestion of the samples and reduction of all forms of Se to Se(IV), which is complete in only 10 min by the use of a focused microwave digestor; and (2) continuous derivatisation (hydride formation) and spectrometry detection by atomic fluorescence. The method can be applied over a wide range of concentrations (0.3-1300 ng ml(-1) of Se) with good repeatability (RSD values lower than 4.6%). The method has been applied successfully to a reference material, and two different types of pharmaceuticals (namely, five different nutritional supplements-with Se present as sodium selenite and Se-methionine-and two shampoos, with selenium sulphide), in agreements with the certified and nominal values, respectively. Yields ranged between 86.5 and 104.8%, and good precision (RSD values lower than 4.2%) were obtained in all instances.

  13. [Indirect determination of rare earth elements in Chinese herbal medicines by hydride generation-atomic fluorescence spectrometry].

    Science.gov (United States)

    Zeng, Chao; Lu, Jian-Ping; Xue, Min-Hua; Tan, Fang-Wei; Wu, Xiao-Yan

    2014-07-01

    Based on their similarity in chemical properties, rare earth elements were able to form stable coordinated compounds with arsenazo III which were extractable into butanol in the presence of diphenylguanidine. The butanol was removed under reduced pressure distillation; the residue was dissolved with diluted hydrochloric acid. As was released with the assistance of KMnO4 and determined by hydrogen generation-atomic fluorescence spectrometry in terms of rare earth elements. When cesium sulfate worked as standard solution, extraction conditions, KMnO4 amount, distillation temperature, arsenazo III amount, interfering ions, etc were optimized. The accuracy and precision of the method were validated using national standard certified materials, showing a good agreement. Under optimum condition, the linear relationship located in 0.2-25 microg x mL(-1) and detection limit was 0.44 microg x mL(-1). After the herbal samples were digested with nitric acid and hydrogen peroxide, the rare earth elements were determined by this method, showing satisfactory results with relative standard deviation of 1.3%-2.5%, and recoveries of 94.4%-106.0%. The method showed the merits of convenience and rapidness, simple instrumentation and high accuracy. With the rare earths enriched into organic phase, the separation of analytes from matrix was accomplished, which eliminated the interference. With the residue dissolved by diluted hydrochloric acid after the solvent was removed, aqueous sample introduction eliminated the impact of organic phase on the tubing connected to pneumatic pump.

  14. Automated system for on-line determination of dimethylarsinic and inorganic arsenic by hydride generation-atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Chaparro, L.L.; Leal, L.O. [Renewable Energy and Environmental Protection Department, Advanced Materials Research Center (CIMAV), Chihuahua, Chihuahua (Mexico); Ferrer, L.; Cerda, V. [University of the Balearic Islands, Department of Chemistry, Palma de Mallorca (Spain)

    2012-09-15

    A multisyringe flow-injection approach has been coupled to hydride generation-atomic fluorescence spectrometry (HG-AFS) with UV photo-oxidation for dimethylarsinic (DMA), inorganic As and total As determination, depending on the pre-treatment given to the sample (extraction or digestion). The implementation of a UV lamp allows on-line photo-oxidation of DMA and the following arsenic detection, whereas a bypass leads the flow directly to the HG-AFS system, performing inorganic arsenic determination. DMA concentration is calculated by the difference of total inorganic arsenic and measurement of the photo-oxidation step. The detection limits for DMA and inorganic arsenic were 0.09 and 0.47 {mu}g L{sup -1}, respectively. The repeatability values accomplished were of 2.4 and 1.8 %, whereas the injection frequencies were 24 and 28 injections per hour for DMA and inorganic arsenic, respectively. This method was validated by means of a solid reference material BCR-627 (muscle of tuna) with good agreement with the certified values. Satisfactory results for DMA and inorganic arsenic determination were obtained in several water matrices. The proposed method offers several advantages, such as increasing the sampling frequency, low detection limits and decreasing reagents and sample consumption, which leads to lower waste generation. (orig.)

  15. Atomic fluorescence spectrometric determination of trace amounts of arsenic and antimony in drinking water by continuous hydride generation.

    Science.gov (United States)

    El-Hadri, F; Morales-Rubio, A; de la Guardia, M

    2000-07-31

    A highly sensitive and simple method has been developed for the determination of As(III), total As, Sb(III) and total Sb in drinking water samples by continuous hydride generation and atomic fluorescence spectrometry (HGAFS). For As determination, water samples aspirated in a carrier of 2 mol l(-1) HCl were merged with a reducing NaBH(4) 3%(m/v) solution, with sample and NaBH(4) flow rates of 12.5 and 1.5 ml min(-1) respectively. The hydride generated in a 170 cm reaction coil was transported to the detector with an Ar flow of 400 ml min(-1), and a limit of detection between 5 and 20 ng l(-1) was obtained. For Sb determination, 2.5 mol l(-1) HCl and 2%(m/v) NaBH(4) were employed, with respective flow rates of 9.7 and 2 ml min(-1). The hydride generated in a 50 cm reaction coil was transported to the detector with an Ar flow rate of 300 ml min(-1), and a limit of detection between 6 and 14 ng l(-1) was obtained. Determination of the total concentration of these elements was obtained after a previous reduction with KI. Recovery studies of different added concentrations of these species in natural water samples were between 93 and 104% for As(III), 96-103% for As(V), 93-101% for Sb(III) and 90-119% for Sb(V).

  16. Determination of arsenite, arsenate, monomethylarsonic acid and dimethylarsinic acid in cereals by hydride generation atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Matos Reyes, M.N. [Department of Analytical Chemistry, University of Valencia, 50 Dr. Moliner Street, 46100 Burjassot, Valencia (Spain); Department of Chemistry, Pontificia Universidade Catolica do Rio de Janeiro, Rua Marques de Sao Vicente, 225, 22453-900, Rio de Janeiro, RJ (Brazil); Cervera, M.L. [Department of Analytical Chemistry, University of Valencia, 50 Dr. Moliner Street, 46100 Burjassot, Valencia (Spain)], E-mail: m.luisa.cervera@uv.es; Campos, R.C. [Department of Chemistry, Pontificia Universidade Catolica do Rio de Janeiro, Rua Marques de Sao Vicente, 225, 22453-900, Rio de Janeiro, RJ (Brazil); Guardia, M. de la [Department of Analytical Chemistry, University of Valencia, 50 Dr. Moliner Street, 46100 Burjassot, Valencia (Spain)

    2007-09-15

    A fast, sensitive and simple non-chromatographic analytical method was developed for the speciation analysis of toxic arsenic species in cereal samples, namely rice and wheat semolina. An ultrasound-assisted extraction of the toxic arsenic species was performed with 1 mol L{sup -1} H{sub 3}PO{sub 4} and 0.1% (m/v) Triton XT-114. After extraction, As(III), As(V), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) concentrations were determined by hydride generation atomic fluorescence spectrometry using a series of proportional equations corresponding to four different experimental reduction conditions. The detection limits of the method were 1.3, 0.9, 1.5 and 0.6 ng g{sup -1} for As(III), As(V), DMA and MMA, respectively, expressed in terms of sample dry weight. Recoveries were always greater than 90%, and no species interconversion occurred. The speciation analysis of a rice flour reference material certified for total arsenic led to coherent results, which were also in agreement with other speciation studies made on the same certified reference material.

  17. Silver stained polyacrylamide gels and fluorescence-based automated capillary electrophoresis for detection of amplified fragment length polymorphism patterns obtained from white-rot fungi in the genus Trametes.

    Science.gov (United States)

    Dresler-Nurmi, A; Terefework, Z; Kaijalainen1, S; Lindström, K; Hatakka, A

    2000-07-01

    Silver stained denaturing polyacrylamide gels (PAGEs) and fluorescent denaturing automated capillary electrophoresis (CE) were used to detect amplified fragment length polymorphism (AFLP) patterns obtained from white-rot fungi belonging to the genus Trametes. AFLP fingerprinting detected by the fluorescence-based method as well as by silver staining showed a high discriminatory power in differentiating nine strains of Trametes ochracea, nine strains of Trametes hirsuta and ten isolates of Trametes versicolor. UPGMA dendrograms derived from fluorescently labelled and silver stained AFLP patterns were similar, but a few differences were detected especially in the clustering of T. ochracea and T. hirsuta strains. Compared to silver-stained AFLP, detection of fluorescent AFLP was fast, reliable and easy to perform and it facilitated surveying with a computerized analysis system. Fluorescent CE seems to be well suited for studying similarity between Trametes species.

  18. Quenching of the OH and nitrogen molecular emission by methane addition in an Ar capacitively coupled plasma to remove spectral interference in lead determination by atomic fluorescence spectrometry

    Science.gov (United States)

    Frentiu, T.; Ponta, M.; Mihaltan, A. I.; Darvasi, E.; Frentiu, M.; Cordos, E.

    2010-07-01

    A new method is proposed to remove the spectral interference on elements in atomic fluorescence spectrometry by quenching of the molecular emission of the OH radical (A 2Σ + → X 2Π) and N 2 second positive system (C 3Π u → B 3Σ g) in the background spectrum of medium power Ar plasmas. The experiments were carried out in a radiofrequency capacitively coupled plasma (275 W, 27.12 MHz) by CH 4 addition. The quenching is the result of the high affinity of OH radical for a hydrogen atom from the CH 4 molecule and the collisions of the second kind between nitrogen excited molecules and CH 4, respectively. The decrease of the emission of N 2 second positive system in the presence of CH 4 is also the result of the deactivation of the metastable argon atoms that could excite the nitrogen molecules. For flow rates of 0.7 l min - 1 Ar with addition of 7.5 ml min - 1 CH 4, the molecular emission of OH and N 2 was completely removed from the plasma jet spectrum at viewing heights above 60 mm. The molecular emission associated to CH and CH 2 species was not observed in the emission spectrum of Ar/CH 4 plasma in the ultraviolet range. The method was experimented for the determination of Pb at 283.31 nm by atomic fluorescence spectrometry with electrodeless discharge lamp and a multichannel microspectrometer. The detection limit was 35 ng ml - 1 , 2-3 times better than in atomic emission spectrometry using the same plasma source, and similar to that in hollow cathode lamp microwave plasma torch atomic fluorescence spectrometry.

  19. Derivation of original RESP atomic partial charges for MD simulations of the LDAO surfactant with AMBER: applications to a model of micelle and a fragment of the lipid kinase PI4KA.

    Science.gov (United States)

    Karakas, Esra; Taveneau, Cyntia; Bressanelli, Stéphane; Marchi, Massimo; Robert, Bruno; Abel, Stéphane

    2017-01-01

    In this paper, we describe the derivation and the validation of original RESP atomic partial charges for the N, N-dimethyl-dodecylamine oxide (LDAO) surfactant. These charges, designed to be fully compatible with all the AMBER force fields, are at first tested against molecular dynamics simulations of pure LDAO micelles and with a fragment of the lipid kinase PIK4A (DI) modeled with the QUARK molecular modeling server. To model the micelle, we used two distinct AMBER force fields (i.e. Amber99SB and Lipid14) and a variety of starting conditions. We find that the micelle structural properties (such as the shape, size, the LDAO headgroup hydration, and alkyl chain conformation) slightly depend on the force field but not on the starting conditions and more importantly are in good agreement with experiments and previous simulations. We also show that the Lipid14 force field should be used instead of the Amber99SB one to better reproduce the C(sp3)C(sp3)C(sp3)C(sp3) conformation in the surfactant alkyl chain. Concerning the simulations with LDAO-DI protein, we carried out different runs at two NaCl concentrations (i.e. 0 and 300 mM) to mimic, in the latter case, the experimental conditions. We notice a small dependence of the simulation results with the LDAO parameters and the salt concentration. However, we find that in the simulations, three out of four tryptophans of the DI protein are not accessible to water in agreement with our fluorescence spectroscopy experiments reported in the paper.

  20. Cloud point extraction for trace inorganic arsenic speciation analysis in water samples by hydride generation atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shan, E-mail: ls_tuzi@163.com; Wang, Mei, E-mail: wmei02@163.com; Zhong, Yizhou, E-mail: yizhz@21cn.com; Zhang, Zehua, E-mail: kazuki.0101@aliyun.com; Yang, Bingyi, E-mail: e_yby@163.com

    2015-09-01

    A new cloud point extraction technique was established and used for the determination of trace inorganic arsenic species in water samples combined with hydride generation atomic fluorescence spectrometry (HGAFS). As(III) and As(V) were complexed with ammonium pyrrolidinedithiocarbamate and molybdate, respectively. The complexes were quantitatively extracted with the non-ionic surfactant (Triton X-114) by centrifugation. After addition of antifoam, the surfactant-rich phase containing As(III) was diluted with 5% HCl for HGAFS determination. For As(V) determination, 50% HCl was added to the surfactant-rich phase, and the mixture was placed in an ultrasonic bath at 70 °C for 30 min. As(V) was reduced to As(III) with thiourea–ascorbic acid solution, followed by HGAFS. Under the optimum conditions, limits of detection of 0.009 and 0.012 μg/L were obtained for As(III) and As(V), respectively. Concentration factors of 9.3 and 7.9, respectively, were obtained for a 50 mL sample. The precisions were 2.1% for As(III) and 2.3% for As(V). The proposed method was successfully used for the determination of trace As(III) and As(V) in water samples, with satisfactory recoveries. - Highlights: • Cloud point extraction was firstly established to determine trace inorganic arsenic(As) species combining with HGAFS. • Separate As(III) and As(V) determinations improve the accuracy. • Ultrasonic release of complexed As(V) enables complete As(V) reduction to As(III). • Direct HGAFS analysis can be performed.

  1. Decoding distinct membrane interactions of HIV-1 fusion inhibitors using a combined atomic force and fluorescence microscopy approach.

    Science.gov (United States)

    Franquelim, Henri G; Gaspar, Diana; Veiga, A Salomé; Santos, Nuno C; Castanho, Miguel A R B

    2013-08-01

    Enfuvirtide and T-1249 are two potent HIV-1 fusion inhibitor peptides. Recent studies indicate that lipids play an important role in the mode of action of those bioactive molecules. Using a combined tandem atomic force microscopy (AFM)-epifluorescence microscopy approach, we studied the interaction of both enfuvirtide and T-1249 with supported lipid bilayers. Fluid (ld)-gel (so) and ld-liquid ordered (lo) phase-separated membrane systems were tested. Results, especially for T-1249, show significant lipid membrane activity at a 15μM peptide concentration. T-1249, in opposition to enfuvirtide, induces an increase in membrane surface roughness, decrease in membrane fluidity, bilayer thinning at ld domains and disruption of the so domain borders. In terms of structural properties, both enfuvirtide and T-1249 possess distinct functional hydrophobic and amphipathic domains of HIV gp41. While enfuvirtide only yields the tryptophan-rich domain (TRD), T-1249 possesses both TRD and pocket-binding domain (PBD). TRD increases the hydrophobicity of the peptide while PBD enhances the amphipathic characteristics. As such, the enhanced membrane activity of T-1249 may be explained by a synergism between its amphipathic N-terminal segment and its hydrophophic C-terminal. Our findings provide valuable insights on the molecular-level mode of action of HIV-1 fusion inhibitors, unraveling the correlation between their structural properties and membrane interactions as a factor influencing their antiviral activity. Ultimately, this work validates the applicability of a combined AFM and fluorescence approach to evaluate the mechanic and structural properties of supported lipid bilayers upon interaction with membrane-active peptides. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. New considerations about the separation and quantification of antimony species by ion chromatography-hydride generation atomic fluorescence spectrometry.

    Science.gov (United States)

    Miravet, R; López-Sánchez, J F; Rubio, R

    2004-10-15

    A new method for the speciation of inorganic [Sb(III) and Sb(V)] and organic (Me3SbCl2) antimony species by using a polystyrene-divinylbenzene-based anion-exchange HPLC column (Hamilton PRP-X100) coupled to hydride generation atomic fluorescence spectrometry (HG-AFS) is presented. Several mobile phases were tested for the baseline separation of these three antimony species, investigating in detail experimental parameters such as concentration and pH. The best efficiency and resolution was achieved by using a gradient elution between diammonium tartrate 250 mmol l(-1) pH 5.5 (A) and KOH 20 mmol l(-1) pH 12 (B). The gradient programme used was 100% B for 1.5 min, decreasing to 0% B in 0.1 min and maintained the elution with 100% A for 5.5 min. Analysis time was less than 7 min. Equilibration of the column with the complexing mobile phase was found to be critical in order to avoid Sb(III) double peak formation. Dilution in diammonium tartrate medium was necessary in order to avoid Sb(III) oxidation at microg l(-1) concentration level. Detection limits of 0.06 microg l(-1) for Sb(V), 0.09 microg l(-1) for Me3SbCl2 and 0.04 microg l(-1) for Sb(III) as well as repeatability and reproducibility better than 5% R.S.D. (n = 10) and 9% R.S.D. (n = 30) (for 1 and 5 microg l(-1) of Sb(V) and Sb(III) and 5 and 10 microg l(-1) of Me3SbCl2) were obtained. Accuracy and recovery studies were carried out by analysing one river freshwater sample and two water certified reference materials. The proposed methodology can be considered reliable and straightforward for antimony speciation in fresh water samples.

  3. The identification, diversity and prevalence of trypanosomes in field caught tsetse in Tanzania using ITS-1 primers and fluorescent fragment length barcoding.

    Science.gov (United States)

    Adams, E R; Hamilton, P B; Malele, I I; Gibson, W C

    2008-07-01

    We report on the development of two generic, PCR-based methods, which replace the multiple species-specific PCR tests used previously to identify the trypanosome species carried by individual tsetse flies. The first method is based on interspecies size variation in the PCR product of the ITS-1 region of the ribosomal RNA (rRNA) locus. In the second approach, length variation of multiple fragments within the 18S and 28S rRNA genes is assayed by PCR amplification with fluorescent primers; products are subsequently sized accurately and rapidly by the use of an automated DNA sequencer. Both methods were used to identify samples collected during large-scale field studies of trypanosome-infected tsetse in Tanzania in the National Parks of Tarangire and Serengeti, and the coastal forest reserve of Msubugwe. The fluctuations of trypanosome prevalence over time and two different field seasons are discussed. As well as facilitating the identification of trypanosome species with increased speed, precision and sensitivity, these generic systems have enabled us to identify two new species of trypanosome.

  4. Exclusion of cytoplasmic fragments in flow cytometric analysis of lymph node samples from dogs with lymphoma using membrane-permeable violet laser-excitable DNA-binding fluorescent dye (DyeCycle Violet).

    Science.gov (United States)

    Ito, Daisuke; O'Brien, Timothy D; Modiano, Jaime F

    2010-12-01

    Cytoplasmic fragments derived from fragile neoplastic lymphocytes are common in samples of lymph nodes collected from dogs with lymphoma. These cytoplasmic fragments interfere with accurate gating of target cells and quantification protocols used for flow cytometry because of their variable size and expression of lymphoid cell surface antigens on their membranes. The aim of this study was to develop a method to efficiently exclude cytoplasmic fragments from flow cytometric analysis of canine lymph nodes in which lymphoma was present. Single-cell suspensions of neoplastic cells were prepared from biopsy samples and fine-needle aspirates of lymph nodes from 23 dogs with lymphoma. Suspensions were stained using a violet laser-excitable (405 nm) membrane-permeable DNA-binding fluorescent dye (DyeCycle Violet [DCV]), incubated with antibodies against CD3, CD5, CD21, CD22, and CD45, and then stained with 7-amino-actinomycin D (7-AAD), an argon-excitable (488 nm) membrane-impermeable DNA-binding fluorescent dye. Multiparameter flow cytometry was used for analysis based on selective uptake and laser-activated fluorescence of these dyes. Cytoplasmic fragments, which were DCV-negative and CD45-positive, and dead cells, which were positive for 7-AAD, were efficiently separated from neoplastic cells. Staining with DCV is a useful method to improve flow cytometric gating methods and quantitative analyses of lymph node samples from dogs with lymphoma. ©2010 American Society for Veterinary Clinical Pathology.

  5. Correlation between Wavelength Dispersive X-ray Fluorescence (WDXRF) analysis of hardened concrete for chlorides vs. Atomic Absorption (AA) analysis in accordance with AASHTO T- 260; sampling and testing for chloride ion in concrete and concrete raw mater

    Science.gov (United States)

    2014-04-01

    A correlation between Wavelength Dispersive X-ray Fluorescence(WDXRF) analysis of Hardened : Concrete for Chlorides and Atomic Absorption (AA) analysis (current method AASHTO T-260, procedure B) has been : found and a new method of analysis has been ...

  6. Development of a MSFIA system for sequential determination of antimony, arsenic and selenium using hydride generation atomic fluorescence spectrometry.

    Science.gov (United States)

    de Santana, Fernanda A; Portugal, Lindomar A; Serra, Antonio M; Ferrer, Laura; Cerdà, Víctor; Ferreira, Sergio L C

    2016-08-15

    This paper proposed a multisyringe flow injection analysis (MSFIA) system for antimony, arsenic and selenium determination in peanut samples by hydride generation atomic fluorescence spectrometry (HG-AFS). The optimization step of the hydride generation was performed using a two-level full factorial design involving the parameters: hydrochloric acid, sodium tetrahydroborate and potassium iodide concentrations. So, using the chemical conditions optimized, this method allows the determination of these elements employing the external calibration technique using aqueous standards with limits of detection and quantification of 0.04 and 0.14µgL(-1) for antimony, 0.04 and 0.14µgL(-1) for arsenic and 0.14 and 0.37µgL(-1) for selenium, respectively. Additionally, the effect of vanadium, chromium, cobalt, nickel, zinc, copper, iron and molybdenum on the generation of chemical vapour was also studied. The precision expressed as relative standard deviation varied from 1.2 to 3.6% for antimony, 1.8-3.9% for arsenic and 1.8-2% for selenium. The accuracy for arsenic and selenium was confirmed using the certified peach leaves reference material SRM 1547 produced by National Institute of Standard and Technology. The proposed method showed 45 injection throughput (h(-1)) using 1.6mL sample volume for each element, 0.8mL NaBH4 0.5% (w/v) containing NaOH 0.05% (w/v), 0.8mL HCl 5M and 0.4mL KI 14% (w/v) containing L-ascorbic acid 2.5% (w/v). The method was applied to the determination of antimony, arsenic and selenium in peanut samples, which were firstly lyophilized and afterward digested using microwave assisted radiation. Six samples were analyzed and the contents of the elements found were: 28.7-41.3µgkg(-1) for arsenic, 86.4-480.1µgkg(-1) for selenium and 32.6-52.4µgkg(-1) for antimony. Addition/recovery tests were also performed to confirm the method accuracy for the three elements. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Fluorescent amplified fragment length polymorphism (FAFLP genotyping demonstrates the role of biofilm-producing methicillin-resistant periocular Staphylococcus epidermidis strains in postoperative endophthalmitis

    Directory of Open Access Journals (Sweden)

    Hasnain Seyed E

    2006-01-01

    Full Text Available Abstract Background An observational case series was used to study the virulence characteristics and genotypes of paired Staphylococcus epidermidis isolates cultured from intraocular samples and from periocular environment of patients with postcataract surgery endophthalmitis. Methods Eight S. epidermidis isolates were obtained from three patients (2 from patients #1 and 2 and 4 from patient #3 whose vitreous and/or anterior chamber (AC specimens and preoperative lid/conjunctiva samples were culture positive. Cultures were identified by API-Staph phenotypic identification system and genotypically characterized by Fluorescent Amplified Fragment Length Polymorphism (FAFLP and checked for their antimicrobial susceptibility. The isolates were tested for biofilm-production and methicillin-resistance (MR by PCR amplification of icaAB and mecA gene respectively. Results Four out of eight S. epidermidis strains showed multiple drug resistance (MDR. All the eight strains were PCR positive for mecA gene whereas seven out of eight strains were positive for icaAB genes. In all three patients FAFLP typing established vitreous isolates of S. epidermidis strains to be indistinguishable from the strains isolated from the patient's conjunctival swabs. However, from patient number three there was one isolate (1030b from lid swab, which appeared to be nonpathogenic and ancestral having minor but significant differences from other three strains from the same patient. This strain also lacked icaAB gene. In silico analysis indicated possible evolution of other strains from this strain in the patient. Conclusion Methicillin-resistant biofilm positive S. epidermidis strains colonizing the conjunctiva and eyelid were responsible for postoperative endophthalmitis (POE.

  8. [Direct determination of water-soluble antimony(III) and antimony(V) in soil by hydride generation atomic fluorescence spectrometry].

    Science.gov (United States)

    Yu, Zhao-Shui; Zhang, Qin

    2009-12-01

    A simple, rapid and useful method for the determination of water-soluble antimony(III) and antimony(V) in soil was established using hydride generation atomic fluorescence spectrometry. The method was based on the different chemical reaction efficiency between Sb(III) and Sb(V) with KBH4 in the media of HCl. The amounts of Sb(III) and Sb(V) can be obtained through measuring antimony fluorescence intensities before and after reduction with reductant. The effects of HCl and KBH4 on the sensitivities of Sb(III) and Sb(V) were investigated, and the interferences from coexistent elements were studied. The reduction efficiencies of both reductants were compared. The detection limits of the method were 1.11 ng x g(-1) for Sb(III) and 1.57 ng x g(-1) for Sb(V). The accuracy of the method was verified by recovery experiments on spiked real soil samples.

  9. Removal of Chromophore-Proximal Polar Atoms Decreases Water Content and Increases Fluorescence in a Near Infrared Phytofluor.

    Science.gov (United States)

    Lehtivuori, Heli; Bhattacharya, Shyamosree; Angenent-Mari, Nicolaas M; Satyshur, Kenneth A; Forest, Katrina T

    2015-01-01

    Genetically encoded fluorescent markers have revolutionized cell and molecular biology due to their biological compatibility, controllable spatiotemporal expression, and photostability. To achieve in vivo imaging in whole animals, longer excitation wavelength probes are needed due to the superior ability of near infrared light to penetrate tissues unimpeded by absorbance from biomolecules or autofluorescence of water. Derived from near infrared-absorbing bacteriophytochromes, phytofluors are engineered to fluoresce in this region of the electromagnetic spectrum, although high quantum yield remains an elusive goal. An invariant aspartate residue is of utmost importance for photoconversion in native phytochromes, presumably due to the proximity of its backbone carbonyl to the pyrrole ring nitrogens of the biliverdin (BV) chromophore as well as the size and charge of the side chain. We hypothesized that the polar interaction network formed by the charged side chain may contribute to the decay of the excited state via proton transfer. Thus, we chose to further probe the role of this amino acid by removing all possibility for polar interactions with its carboxylate side chain by incorporating leucine instead. The resultant fluorescent protein, WiPhy2, maintains BV binding, monomeric status, and long maximum excitation wavelength while minimizing undesirable protoporphyrin IXα binding in cells. A crystal structure and time-resolved fluorescence spectroscopy reveal that water near the BV chromophore is excluded and thus validate our hypothesis that removal of polar interactions leads to enhanced fluorescence by increasing the lifetime of the excited state. This new phytofluor maintains its fluorescent properties over a broad pH range and does not suffer from photobleaching. WiPhy2 achieves the best compromise to date between high fluorescence quantum yield and long illumination wavelength in this class of fluorescent proteins.

  10. Removal of Chromophore-proximal Polar Atoms Decreases Water Content and Increases Fluorescence in a Near Infrared Phytofluor

    Directory of Open Access Journals (Sweden)

    Heli eLehtivuori

    2015-11-01

    Full Text Available Genetically encoded fluorescent markers have revolutionized cell and molecular biology due to their biological compatibility, controllable spatiotemporal expression, and photostability. To achieve in vivo imaging in whole animals, longer excitation wavelength probes are needed due to the superior ability of near infrared light to penetrate tissues unimpeded by absorbance from biomolecules or autofluorescence of water. Derived from near infrared-absorbing bacteriophytochromes, phytofluors are engineered to fluoresce in this region of the electromagnetic spectrum, although high quantum yield remains an elusive goal. An invariant aspartate residue is of utmost importance for photoconversion in native phytochromes, presumably due to the proximity of its backbone carbonyl to the pyrrole ring nitrogens of the biliverdin (BV chromophore as well as the size and charge of the side chain. We hypothesized that the polar interaction network formed by the charged side chain may contribute to the decay of the excited state via proton transfer. Thus, we chose to further probe the role of this amino acid by removing all possibility for polar interactions with its carboxylate side chain by incorporating leucine instead. The resultant fluorescent protein, WiPhy2, maintains BV binding, monomeric status, and long maximum excitation wavelength while minimizing undesirable protoporphyrin IXα binding in cells. A crystal structure and time-resolved fluorescence spectroscopy reveal that water near the BV chromophore is excluded and thus validate our hypothesis that removal of polar interactions leads to enhanced fluorescence by increasing the lifetime of the excited state. This new phytofluor maintains its fluorescent properties over a broad pH range and does not suffer from photobleaching. WiPhy2 achieves the best compromise to date between high fluorescence quantum yield and long illumination wavelength in this class of fluorescent proteins.

  11. Large time-asymmetric quantum fluctuations in amplitude–intensity correlation measurements of V-type three-level atom resonance fluorescence

    Science.gov (United States)

    Gutiérrez, L.; Castro-Beltrán, H. M.; Román-Ancheyta, R.; Horvath, L.

    2017-11-01

    In this paper we show that the scattered field of a bichromatically driven V-type three-level atom exhibit asymmetry and large violation of classical bounds in amplitude-intensity correlations. These features result from the noncommutativity of amplitude and intensity field operators, and the strong non-Gaussian fluctuations in this system. The amplitude-intensity correlations of resonance fluorescence, with its large third-order fluctuations, describe the nonclassical features of the emitted field more accurately than the second-order measure related to squeezing. Spectra and variances of these correlations, along intensity-intensity correlations, provide a wealth of supporting information.

  12. Density relaxation and particle motion characteristics in a non-ionic deep eutectic solvent (acetamide + urea): Time-resolved fluorescence measurements and all-atom molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Das, Anuradha; Das, Suman; Biswas, Ranjit, E-mail: ranjit@bose.res.in [Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata, West Bengal 700098 (India)

    2015-01-21

    Temperature dependent relaxation dynamics, particle motion characteristics, and heterogeneity aspects of deep eutectic solvents (DESs) made of acetamide (CH{sub 3}CONH{sub 2}) and urea (NH{sub 2}CONH{sub 2}) have been investigated by employing time-resolved fluorescence measurements and all-atom molecular dynamics simulations. Three different compositions (f) for the mixture [fCH{sub 3}CONH{sub 2} + (1 − f)NH{sub 2}CONH{sub 2}] have been studied in a temperature range of 328-353 K which is ∼120-145 K above the measured glass transition temperatures (∼207 K) of these DESs but much lower than the individual melting temperature of either of the constituents. Steady state fluorescence emission measurements using probe solutes with sharply different lifetimes do not indicate any dependence on excitation wavelength in these metastable molten systems. Time-resolved fluorescence anisotropy measurements reveal near-hydrodynamic coupling between medium viscosity and rotation of a dissolved dipolar solute. Stokes shift dynamics have been found to be too fast to be detected by the time-resolution (∼70 ps) employed, suggesting extremely rapid medium polarization relaxation. All-atom simulations reveal Gaussian distribution for particle displacements and van Hove correlations, and significant overlap between non-Gaussian (α{sub 2}) and new non-Gaussian (γ) heterogeneity parameters. In addition, no stretched exponential relaxations have been detected in the simulated wavenumber dependent acetamide dynamic structure factors. All these results are in sharp contrast to earlier observations for ionic deep eutectics with acetamide [Guchhait et al., J. Chem. Phys. 140, 104514 (2014)] and suggest a fundamental difference in interaction and dynamics between ionic and non-ionic deep eutectic solvent systems.

  13. Surface passivation of nano-textured fluorescent SiC by atomic layer deposited TiO2

    DEFF Research Database (Denmark)

    Lu, Weifang; Ou, Yiyu; Jokubavicius, Valdas

    2016-01-01

    reflectance increases with TiO2 thickness due to increased surface diffuse reflection. The passivation effect of ALD TiO2 thin film on the nano-textured fluorescent 6H-SiC sample was also investigated and a PL intensity improvement of 8.05% was obtained due to the surface passivation....

  14. Atomic force microscopy study of the antigen-antibody binding force on patient cancer cells based on ROR1 fluorescence recognition.

    Science.gov (United States)

    Li, Mi; Xiao, Xiubin; Liu, Lianqing; Xi, Ning; Wang, Yuechao; Dong, Zaili; Zhang, Weijing

    2013-09-01

    Knowledge of drug-target interaction is critical to our understanding of drug action and can help design better drugs. Due to the lack of adequate single-molecule techniques, the information of individual interactions between ligand-receptors is scarce until the advent of atomic force microscopy (AFM) that can be used to directly measure the individual ligand-receptor forces under near-physiological conditions by linking ligands onto the surface of the AFM tip and then obtaining force curves on cells. Most of the current AFM single-molecule force spectroscopy experiments were performed on cells grown in vitro (cell lines) that are quite different from the human cells in vivo. From the view of clinical practice, investigating the drug-target interactions directly on the patient cancer cells will bring more valuable knowledge that may potentially serve as an important parameter in personalized treatment. Here, we demonstrate the capability of AFM to measure the binding force between target (CD20) and drug (rituximab, an anti-CD20 monoclonal antibody targeted drug) directly on lymphoma patient cancer cells under the assistance of ROR1 fluorescence recognition. ROR1 is a receptor expressed on some B-cell lymphomas but not on normal cells. First, B-cell lymphoma Raji cells (a cell line) were used for ROR1 fluorescence labeling and subsequent measurement of CD20-rituximab binding force. The results showed that Raji cells expressed ROR1, and the labeling of ROR1 did not influence the measurement of CD20-rituximab binding force. Then the established experimental procedures were performed on the pathological samples prepared from the bone marrow of a follicular lymphoma patient. Cancer cells were recognized by ROR1 fluorescence. Under the guidance of fluorescence, with the use of a rituximab-conjugated tip, the cellular topography was visualized by using AFM imaging and the CD20-Rituximab binding force was measured by single-molecule force spectroscopy. Copyright © 2013

  15. COMPARISON OF FEMTOSECOND AND NANOSECOND TWO PHOTON ABSORPTION LASER INDUCED FLUORESCENCE (TALIF) OF ATOMIC OXYGEN IN ATMOSPHERIC PRESSURE PLASMAS

    Science.gov (United States)

    2016-08-01

    Division (AFRL/RQQE) Combustion Branch, Turbine Engine Division (AFRL/RQTC) Jacob B. Schmidt and Sukesh Roy Spectral Energies LLC Brian Sands ...quenching coefficient, kqi. The effective quenching coefficient is measured by directly monitoring the fluorescence decay in both the plasma jet and...gas added directly to the unpowered helium jet for signal calibration [Van Gessel et al. 2013]. In this method, effective branching ratios aXe were

  16. Diagnostics of Carbon Nanotube Formation in a Laser Produced Plume: An Investigation of the Metal Catalyst by Laser Ablation Atomic Fluorescence Spectroscopy

    Science.gov (United States)

    deBoer, Gary; Scott, Carl

    2003-01-01

    Carbon nanotubes, elongated molecular tubes with diameters of nanometers and lengths in microns, hold great promise for material science. Hopes for super strong light-weight material to be used in spacecraft design is the driving force behind nanotube work at JSC. The molecular nature of these materials requires the appropriate tools for investigation of their structure, properties, and formation. The mechanism of nanotube formation is of particular interest because it may hold keys to controlling the formation of different types of nanotubes and allow them to be produced in much greater quantities at less cost than is currently available. This summer's work involved the interpretation of data taken last summer and analyzed over the academic year. The work involved diagnostic studies of carbon nanotube formation processes occurring in a laser-produced plume. Laser ablation of metal doped graphite to produce a plasma plume in which carbon nanotubes self assemble is one method of making carbon nanotube. The laser ablation method is amenable to applying the techniques of laser spectroscopy, a powerful tool for probing the energies and dynamics of atomic and molecular species. The experimental work performed last summer involved probing one of the metal catalysts, nickel, by laser induced fluorescence. The nickel atom was studied as a function of oven temperature, probe laser wavelength, time after ablation, and position in the laser produced plume. This data along with previously obtained data on carbon was analyzed over the academic year. Interpretations of the data were developed this summer along with discussions of future work. The temperature of the oven in which the target is ablated greatly influences the amount of material ablated and the propagation of the plume. The ablation conditions and the time scale of atomic and molecular lifetimes suggest that initial ablation of the metal doped carbon target results in atomic and small molecular species. The metal

  17. Speciation analysis of organoarsenical compounds in biological matrices by coupling ion chromatography to atomic fluorescence spectrometry with on-line photooxidation and hydride generation

    Energy Technology Data Exchange (ETDEWEB)

    Simon, S.; Lobos, G.; Pannier, F.; De Gregori, I.; Pinochet, H.; Potin-gautier, M

    2004-09-06

    The optimisation of an on-line decomposition based on UV photooxidation for the analysis of organoarsenic species by coupling cation-exchange chromatography and atomic fluorescence spectrometry with hydride generation, is described. In this study, special consideration is given to the compatibility of mobile phases with post-column treatments. Results show that the most commonly used mobile phase, aqueous pyridine solutions, decreases species conversion efficiency, leading to a significant loss of sensitivity. New fully-compatible chromatographic conditions are proposed to separate arsenobetaine, arsenocholine, trimethylarsine oxide and tetramethylarsonium ion within 20 min. The very low absolute limits of detection, 4-12 pg(As), allow speciation at trace levels. Analysis of a certified reference fish tissue (DORM-2) and other seafood samples (French and Chilean oysters and mussel) highlights the robustness and the accuracy of the optimised system.

  18. [Butanol extraction combined with dilute hydrochloric acid dissolution-atomic fluorescence spectrometric method for indirect determination of molybdenum in Chinese herbal medicine].

    Science.gov (United States)

    Lu, Jian-Ping; Geng, Guo-Xing; Tang, Yan-Kui; Lu, Zhi-Yong

    2012-12-01

    A method for indirectly determining the molybdenum in Chinese herbal medicine by butanol extraction and dilute hydrochloric acid dissolution was established for atomic fluorescence spectrometry. The molybdoarsenate heteropoly acid, formed in the presence of As(V) and ammonium molybdate in 0.3 mol x L(-1) sulphuric acid medium, was separated and enriched in the organic solvent, then the evaporation of organic reagent was implemented and the left residue was dissolved in dilute hydrochloric acid in which the arsenic content was determined on behalf of molybdenum. In the optimum experimental conditions, molybdenum content in 0-15 microg x L(-1) range depicts a good linear relationship, the detection limit and relative standard deviation of 0.44 microg x L(-1) and 1.1% were obtained, respectively. Spiked Chinese herbal medicine samples were determined with the proposed method, and recoveries of 95.6%-101.3% were achieved.

  19. Impact of fluorescence emission from gold atoms on surrounding biological tissue-implications for nanoparticle radio-enhancement.

    Science.gov (United States)

    Byrne, H L; Gholami, Y; Kuncic, Z

    2017-04-21

    The addition of gold nanoparticles within target tissue (i.e. a tumour) to enhance the delivered radiation dose is a well studied radiotherapy treatment strategy, despite not yet having been translated into standard clinical practice. While several studies have used Monte Carlo simulations to investigate radiation dose enhancement by Auger electrons emitted from irradiated gold nanoparticles, none have yet considered the effects due to escaping fluorescence photons. Geant4 was used to simulate a water phantom containing 10 mg ml -1 uniformly dispersed gold (1% by mass) at 5 cm depth. Incident monoenergetic photons with energies either side of the gold K-edge at 73 keV and 139.5 keV were chosen to give the same attenuation contrast against water, where water is used as a surrogate for biological tissue. For 73 keV incident photons, adding 1% gold into the water phantom enhances the energy deposited in the phantom by a factor of  ≈1.9 while 139.5 keV incident photons give a lower enhancement ratio of  ≈1.5. This difference in enhancement ratio, despite the equivalent attenuation ratios, can be attributed to energy carried from the target into the surrounding volume by fluorescence photons for the higher incident photon energy. The energy de-localisation is maximal just above the K-edge with 36% of the initial energy deposit in the phantom lost to escaping fluorescence photons. Conversely we find that the absorption of more photons by gold in the phantom reduces the number of scattered photons and hence energy deposited in the surrounding volume by up to 6% for incident photons below the K-edge. For incident photons above the K-edge this is somewhat offset by fluorescence. Our results give new insight into the previously unstudied centimetre scale energy deposition outside a target, which will be valuable for the future development of treatment plans using gold nanoparticles. From these results, we can conclude that gold nanoparticles delivered

  20. Hydride generation atomic fluorescence spectrometric determination of As, Bi, Sb, Se(IV) and Te(IV) in aqua regia extracts from atmospheric particulate matter using multivariate optimization

    Energy Technology Data Exchange (ETDEWEB)

    Moscoso-Perez, Carmen [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Moreda-Pineiro, Jorge [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain)]. E-mail: jmoreda@udc.es; Lopez-Mahia, Purificacion [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Muniategui-Lorenzo, Soledad [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Fernandez-Fernandez, Esther [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Prada-Rodriguez, Dario [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain)

    2004-11-22

    A highly sensitive and simple method, based on hydride generation and atomic fluorescence detection, has been developed for the determination of As, Bi, Sb, Se(IV) and Te(IV) in aqua regia extracts from atmospheric particulate matter samples. Atmospheric particulates matter was collected on glass fiber filters using a medium volume sampler (PM1 particulate matter). Two-level factorial designs have been used to optimise the hydride generation atomic fluorescence spectrometry (HG-AFS) procedure. The effects of several parameters affecting the hydride generation efficiency (hydrochloric acid, sodium tetrahydroborate and potassium iodide concentrations and flow rates) have been evaluated using a Plackett-Burman experimental design. In addition, parameters affecting the hydride measurement (delay, analysis and memory times) have been also investigated. The significant parameters obtained (sodium tetrahydroborate concentration, sodium tetrahydroborate flow rate and analysis time for As; hydrochloric acid concentration and sodium tetrahydroborate flow rate for Se(IV); and sodium tetrahydroborate concentration and sodium tetrahydroborate flow rate for Te(IV)) have been optimized by using 2{sup n} + star central composite design. Hydrochloric acid concentration and sodium tetrahydroborate flow rate were the significant parameters obtained for Sb and Bi determination, respectively. Using a univariate approach these parameters were optimized. The accuracy of methods have been verified by using several certified reference materials: SRM 1648 (urban particulate matter) and SRM 1649a (urban dust). Detection limits in the range of 6 x 10{sup -3} to 0.2 ng m{sup -3} have been achieved. The developed methods were applied to several atmospheric particulate matter samples corresponding to A Coruna city (NW Spain)

  1. Intracellular concentration map of magnesium in whole cells by combined use of X-ray fluorescence microscopy and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lagomarsino, Stefano, E-mail: stefano.lagomarsino@cnr.it [IPCF-CNR -UOS Roma c/o Dip Fisica Universita' ' Sapienza' , P.le A. Moro, 2 Rome (Italy); Physics Department, Universita' Sapienza, P.le A. Moro, 2 Rome (Italy); Iotti, Stefano [Dipartimento di Medicina Interna, dell' Invecchiamento e Malattie Nefrologiche Universita di Bologna, Via Massarenti, 9 40138 Bologna (Italy); Istituto Nazionale Biostrutture e Biosistemi - Rome (Italy); Farruggia, Giovanna [Dipartimento di Biochimica ' G. Moruzzi' Universita di Bologna, Via Irnerio, 48 40126 Bologna (Italy); Cedola, Alessia [IFN-CNR - V. Cineto Romano, 42 00156 Rome (Italy); Trapani, Valentina [Istituto di Patologia Generale - Universita Cattolica del Sacro Cuore - Facolta di Medicina ' A. Gemelli' L.go F. Vito, 1 00168 Rome (Italy); Fratini, Michela [IFN-CNR - V. Cineto Romano, 42 00156 Rome (Italy); Bukreeva, Inna [IFN-CNR - V. Cineto Romano, 42 00156 Rome (Italy); Shubnikov Institute of Crystallography, Leninskii prospekt 59, Moscow, 119333 (Russian Federation); Notargiacomo, Andrea [IFN-CNR - V. Cineto Romano, 42 00156 Rome (Italy); Mastrototaro, Lucia [Istituto di Patologia Generale - Universita Cattolica del Sacro Cuore - Facolta di Medicina ' A. Gemelli' L.go F. Vito, 1 00168 Rome (Italy); Marraccini, Chiara [Dipartimento di Medicina Interna, dell' Invecchiamento e Malattie Nefrologiche Universita di Bologna, Via Massarenti, 9 40138 Bologna (Italy); and others

    2011-11-15

    We report a novel experimental approach to derive quantitative concentration map of light elements in whole cells by combining two complementary nano-probe methods: X-ray fluorescence microscopy (XRFM) and atomic force microscopy (AFM). The concentration is derived by normalizing point-by-point the elemental (here Mg) spatial distribution obtained by XRFM, by the thickness measured using AFM. The considerable difference between the elemental distribution and the concentration maps indicates that this procedure is essential to obtain reliable information on the role and function of elements in whole cells. - Highlights: Black-Right-Pointing-Pointer X-ray fluorescence and AFM have been measured on the same de-hydrated whole cells. Black-Right-Pointing-Pointer The element distribution has been normalized point-by-point by the cell thickness. Black-Right-Pointing-Pointer The element (Mg) concentration map has been obtained on a whole cell. Black-Right-Pointing-Pointer The element concentration map is quite different from the distribution map. Black-Right-Pointing-Pointer Higher Mg concentration is found in the cell periphery.

  2. DFT Conformation and Energies of Amylose Fragments at Atomic Resolution Part 2: “Band-flip” and “Kink” Forms of Alpha-Maltotetraose

    Science.gov (United States)

    In Part 2 of this series of DFT optimization studies of '-maltotetraose, we present results at the B3LYP/6-311++G** level of theory for conformations denoted “band-flips” and “kinks”. Recent experimental X-ray studies have found examples of amylose fragments with conformations distorted from the us...

  3. Assessment of homogeneity and minimum sample mass for cadmium analysis in powdered certified reference materials and real rice samples by solid sampling electrothermal vaporization atomic fluorescence spectrometry.

    Science.gov (United States)

    Mao, Xuefei; Liu, Jixin; Huang, Yatao; Feng, Li; Zhang, Lihua; Tang, Xiaoyan; Zhou, Jian; Qian, Yongzhong; Wang, Min

    2013-01-30

    To optimize analytical quality controls of solid sampling electrothermal vaporization atomic fluorescence spectrometry (SS-ETV-AFS), the homogeneity (H(E)) of rice samples and their minimum sample mass (M) for cadmium analysis were evaluated using three certified reference materials (CRMs) and real rice samples. The effects of different grinding degrees (particle sizes 1 mm) on H(E) and M of real rice samples were also investigated. The calculated M values of three CRMs by the Pauwels equation were 2.19, 19.76, and 3.79 mg. The well-ground real rice samples (particle size method were compared with the results by microwave digestion graphite furnace atomic absorption spectrometry with a 0.5 g sample mass. There was no significant difference between these two methods, which meant that SS-ETV-AFS could be used to accurately detect Cd in rice with several milligrams of samples instead of the certified value (200 mg) or the recommended mass (200-500 mg) of the methods of the Association of Official Analytical Chemists.

  4. Cross section measurements of the processes occurring in the fragmentation of H{sub n}{sup +} (3 {<=} n {<=} 35) hydrogen clusters induced by high speed (60 keV/u) collisions on helium atoms; Mesure des sections efficaces des differents processus intervenant dans la fragmentation d`agregats d`hydrogene H{sub n}{sup +} (3 {<=} n {<=} 35) induite par collision a haute vitesse (60 keV/u) sur un atome d`helium

    Energy Technology Data Exchange (ETDEWEB)

    Louc, Sandrine [Inst. de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France)

    1997-09-15

    Different processes involved in the fragmentation of ionised hydrogen clusters H{sub 3} + (H{sub 2}){sub (n-3)/2} (n = 5-35) have been studied in the same experiment: the fragmentation of the cluster is induced by the collision with an helium atom at high velocity ({approx_equal} c/100). The collision is realised in reversed kinematic - clusters are accelerated - which allows the detection of neutral and charged fragments. The different channels of fragmentation are identified by using coincidence techniques. For all the cluster sizes studied the capture cross sections of one electron of the target by the cluster is equal to the capture cross section of the H{sub 3}{sup +} ion. In the same way, the dissociation cross section of the H{sub 3}{sup +} core of the cluster does not depend on cluster size. These fragmentation processes are due to the interaction of H{sub 3}{sup +} core of the cluster and the helium atom without ionization of another component of the cluster. On the contrary, the cross sections of loss of one, two and three molecules by the cluster and the dissociation cross section of the cluster in all its molecular components depends strongly on the cluster size. This dependence is different from the one measured for the metastable decay of the cluster. Thus, the process of loss of molecules induced by a collision should correspond to a different dissociation mechanism. In regard of the singularities observed for the size dependence, the H{sub 9}{sup +}, H{sub 15}{sup +}, H{sub 19}{sup +} and H{sub 29}{sup +} clusters could be the `core` of the biggest clusters. These observation are in agreement with the size effects of smaller magnitude observed for the dissociation cross section (all the processes). The values of the cross section for the process of at least one ionization of the cluster indicate that about 80% of the fragmentation events result from this process. (author) 114 refs., 74 figs., 9 tabs.

  5. Identification of cultured isolates of clinically important yeast species using fluorescent fragment length analysis of the amplified internally transcribed rRNA spacer 2 region

    Directory of Open Access Journals (Sweden)

    Muylaert An

    2002-07-01

    Full Text Available Abstract Background The number of patients with yeast infection has increased during the last years. Also the variety of species of clinical importance has increased. Correct species identification is often important for efficient therapy, but is currently mostly based on phenotypic features and is sometimes time-consuming and depends largely on the expertise of technicians. Therefore, we evaluated the feasibility of PCR-based amplification of the internally transcribed spacer region 2 (ITS2, followed by fragment size analysis on the ABI Prism 310 for the identification of clinically important yeasts. Results A rapid DNA-extraction method, based on simple boiling-freezing was introduced. Of the 26 species tested, 22 could be identified unambiguously by scoring the length of the ITS2-region. No distinction could be made between the species Trichosporon asteroides and T. inkin or between T. mucoides and T. ovoides. The two varieties of Cryptococcus neoformans (var. neoformans and var. gattii could be differentiated from each other due to a one bp length difference of the ITS2 fragment. The three Cryptococcus laurentii isolates were split into two groups according to their ITS2-fragment lengths, in correspondence with the phylogenetic groups described previously. Since the obtained fragment lengths compare well to those described previously and could be exchanged between two laboratories, an internationally usable library of ITS2 fragment lengths can be constructed. Conclusions The existing ITS2 size based library enables identification of most of the clinically important yeast species within 6 hours starting from a single colony and can be easily updated when new species are described. Data can be exchanged between laboratories.

  6. Spatial dynamics of laser-induced fluorescence in an intense laser beam: experiment and theory in alkali metal atoms

    CERN Document Server

    Auzinsh, Marcis; Ferber, Ruvin; Gahbauer, Florian; Kalnins, Uldis

    2015-01-01

    We have shown that it is possible to model accurately optical phenomena in intense laser fields by taking into account the intensity distribution over the laser beam. We developed a theoretical model that divided an intense laser beam into concentric regions, each with a Rabi frequency that corresponds to the intensity in that region, and solved a set of coupled optical Bloch equations for the density matrix in each region. Experimentally obtained magneto-optical resonance curves for the $F_g=2\\longrightarrow F_e=1$ transition of the $D_1$ line of $^{87}$Rb agreed very well with the theoretical model up to a laser intensity of around 200 mW/cm$^2$ for a transition whose saturation intensity is around 4.5 mW/cm$^2$. We have studied the spatial dependence of the fluorescence intensity in an intense laser beam experimentally and theoretically. An experiment was conducted whereby a broad, intense pump laser excited the $F_g=4\\longrightarrow F_e=3$ transition of the $D_2$ line of cesium while a weak, narrow probe ...

  7. Immobilisation of oligo-peptidic probes for microarray implementation: characterisation by FTIR, atomic force microscopy and 2D fluorescence.

    Science.gov (United States)

    Soultani-Vigneron, S; Dugas, V; Rouillat, M H; Fédollière, J; Duclos, M C; Vnuk, E; Phaner-Goutorbe, M; Bulone, V; Martin, J R; Wallach, J; Cloarec, J P

    2005-08-05

    Proteomic microarrays show a wide range of applications for the investigation of DNA-protein, enzyme-substrate as well as protein-protein interactions. Among many challenges to build a viable "protein microarray", the surface chemistry that will allow to immobilised various proteins to retain their biological activity is of paramount importance. Here we report a chemical functionalisation method allowing immobilisation of oligo-peptides onto silica surface (porous silica, glass, thermal silicon dioxide). Substrates were first derivatised with a monofunctional silane allowing the elaboration of dense and uniform monolayers in highly reproducible way. Prior to the oligo-peptides grafting, this organic layer was functionalised with an amino-polyethyleneglycol. The coupling step of oligo-peptides onto functionalised supports is achieved through activation of the C-terminal function of the oligo-peptides. Chemical surface modifications were followed by FTIR spectroscopy, AFM measurements and fluorescence scanning microscopy. A systematic study of the oligo-peptide grafting conditions (time, concentration, solvent) was carried out to optimise this step. The oligo-peptides grafting strategy implemented in this work ensure a covalent and oriented grafting of the oligo-peptides. This orientation is ensured through the use of fully protected peptide except the terminal primary amine. The immobilized peptides will be then deprotected before biological recognition. This strategy is crucial to retain the biological activity of thousands of oligo-probes assessed on a microarray.

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

    DEFF Research Database (Denmark)

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

    2004-01-01

    . Isolates with identical DNA profiles were distributed across the spectrum of origin. It was not possible to associate certain types with specific food sectors or clinical cases, which is indicative of the spread of L. monocytogenes clones across species. Overall, AFLP fingerprinting was suitable...... of different origin. The AFLP technique was compared with three other molecular typing methods - ribotyping, random amplified polymorphic DNA analysis (RAPD), and pulsed-field gel electrophoresis (PFGE) - in terms of discriminatory ability. PCR-restriction fragment length polymorphism was included......, while another main cluster consisted of all of the 72 L. monocytogenes hly allele 2 strains. This indicates the existence of two distinct phylogenetic divisions. Isolates of the remaining Listeria species were not included in the clusters. AFLP, PFGE, and RAPD typing were highly discriminatory methods...

  9. Experimental evidence of resonant energy collisional transfers between argon 1s and 2p states and ground state H atoms by laser collisional induced fluorescence

    Science.gov (United States)

    Carbone, Emile; van Dijk, Jan; Kroesen, Gerrit

    2015-04-01

    In this paper, laser collisional induced fluorescence (LCIF) is used to probe resonant excitation transfers in an argon/hydrogen plasma resulting from heavy particle collisions. Different radiative transitions between the 1s and 2p states (in Paschen's notation) of argon are optically pumped by a nanosecond laser pulse. The spontaneous fluorescence and collisional responses of the argon and hydrogen systems are monitored by optical emission spectroscopy. A surfatron plasma source is used to generate an argon plasma with a few per cent hydrogen addition at pressures between 0.65 and 20 mbar. The electron density is measured independently by means of Thomson scattering. The overall response of the plasma due to optical pumping of argon is briefly discussed and an overview of the known heteronuclear excitation transfers in an argon/hydrogen plasma is given. The propagation of the shortcut in the Ar(1s) to H(n = 2) excitation transfer due to the optical pumping of the Ar(1s) states is seen in the atomic hydrogen LCIF responses. For the first time, we give direct experimental evidence of the existence of an efficient excitation transfer: Additionally, measurements are performed in order to estimate the resonant energy transfer between the resonant argon 1s states and hydrogen atoms: for which no previously measured cross sections could be found in the literature. These are extra quenching channels of argon 1s and 2p states that should be included in collisional-radiative modeling of argon-hydrogen discharges. The high repetition rate of the dye laser allows us to obtain a high sensitivity in the measurements. LCIF is shown to be a powerful tool for unraveling electron and also heavy particle excitation channels in situ in the plasma phase. The technique was previously developed for measuring electron or species densities locally in the plasma, but we show that it can be advantageously used to probe collisional transfers between very short-lived species which exist

  10. Arsenic speciation in edible alga samples by microwave-assisted extraction and high performance liquid chromatography coupled to atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Salgado, S. [Departamento de Ingenieria Civil: Tecnologia Hidraulica y Energetica, Escuela Universitaria de Ingenieria Tecnica de Obras Publicas, Universidad Politecnica de Madrid, Alfonso XII 3 y 5, 28014 Madrid (Spain); Quijano, M.A., E-mail: marian.quijano@upm.es [Departamento de Ingenieria Civil: Tecnologia Hidraulica y Energetica, Escuela Universitaria de Ingenieria Tecnica de Obras Publicas, Universidad Politecnica de Madrid, Alfonso XII 3 y 5, 28014 Madrid (Spain); Bonilla, M.M. [Departamento de Ingenieria Civil: Tecnologia Hidraulica y Energetica, Escuela Universitaria de Ingenieria Tecnica de Obras Publicas, Universidad Politecnica de Madrid, Alfonso XII 3 y 5, 28014 Madrid (Spain)

    2012-02-10

    Highlights: Black-Right-Pointing-Pointer Total As and As species were analyzed in edible marine algae. Black-Right-Pointing-Pointer A microwave-assisted extraction method with deionized water was applied. Black-Right-Pointing-Pointer As compounds identified comprised DMA, As(V) and four arsenosugars Black-Right-Pointing-Pointer Considerably high As(V) concentrations were found in the most of the algae studied. - Abstract: Twelve commercially available edible marine algae from France, Japan and Spain and the certified reference material (CRM) NIES No. 9 Sargassum fulvellum were analyzed for total arsenic and arsenic species. Total arsenic concentrations were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) after microwave digestion and ranged from 23 to 126 {mu}g g{sup -1}. Arsenic species in alga samples were extracted with deionized water by microwave-assisted extraction and showed extraction efficiencies from 49 to 98%, in terms of total arsenic. The presence of eleven arsenic species was studied by high performance liquid chromatography-ultraviolet photo-oxidation-hydride generation atomic-fluorescence spectrometry (HPLC-(UV)-HG-AFS) developed methods, using both anion and cation exchange chromatography. Glycerol and phosphate sugars were found in all alga samples analyzed, at concentrations between 0.11 and 22 {mu}g g{sup -1}, whereas sulfonate and sulfate sugars were only detected in three of them (0.6-7.2 {mu}g g{sup -1}). Regarding arsenic toxic species, low concentration levels of dimethylarsinic acid (DMA) (<0.9 {mu}g g{sup -1}) and generally high arsenate (As(V)) concentrations (up to 77 {mu}g g{sup -1}) were found in most of the algae studied. The results obtained are of interest to highlight the need to perform speciation analysis and to introduce appropriate legislation to limit toxic arsenic species content in these food products.

  11. On-line continuous generation of zinc chelates in the vapor phase by reaction with sodium dithiocarbamates and determination by atomic fluorescence spectrometry

    Science.gov (United States)

    Duan, Xuchuan; Sun, Rui; Fang, Jinliang

    2017-02-01

    The present study shows for the first time that a volatile zinc chelate species can be generated by the on-line continuous merging of an acidified sample solution with an aqueous sodium diethyldithiocarbamate solution followed by rapid separation using a frit-based bubble gas-liquid separator at room temperature. The operating conditions for the generation of the vaporous zinc chelate were preliminarily investigated by non-dispersive atomic fluorescence spectrometry. The possible mechanism of zinc vapor generation is discussed. The study shows that the volatile species is an intermediate species with very similar properties to diethyldithiocarbamic acid and a very short half-life in the acidic solution. Moreover, this species can only be generated by on-line mixing and rapid separation. The efficiency of generation was 33-85% depending on acidity. Under optimal conditions, the flow rates of the sample and Na-DDTC solution were 1.3 ml min- 1, the carrier argon flow rate was 225 ml min- 1, the acid concentration of the sample solution and the concentration of Na-DDTC were 0.05 M and 0.4% (m/v), respectively, the detection limit of zinc was 0.33 (3σ) ng ml- 1, and the relative standard deviation (RSD) was 1.3%. The accuracy of the method was verified by the determination of zinc in the plant reference materials GBW10015 (spinach) and GBW10045 (rice). The results were in good agreement with the certified reference values.

  12. Solid Phase Extraction of Inorganic Mercury Using 5-Phenylazo-8-hydroxyquinoline and Determination by Cold Vapor Atomic Fluorescence Spectroscopy in Natural Water Samples

    Directory of Open Access Journals (Sweden)

    Mirna Daye

    2013-01-01

    Full Text Available 8-Hydroxyquinoline (8-HQ was chosen as a powerful ligand for Hg solid phase extraction. Among several chelating resins based on 8-HQ, 5-phenylazo-8-hydroxyquinoline (5Ph8HQ is used for mercury extraction in which the adsorption dynamics were fully studied. It has been shown that Hg(II is totally absorbed by 5Ph8HQ within the first 30 minutes of contact time with t1/2 5 minutes, following Langmuir adsorption model. At pH 4, the affinity of mercury is unchallenged by other metals except, for Cu(II, which have shown higher Kd value. With these latter characteristics, 5Ph8HQ was examined for the preconcentration of trace levels of Hg(II. The developed method showed quantitative recoveries of Hg(II with LOD = 0.21 pg mL−1 and RSD = 3–6% using cold vapor atomic fluorescence spectroscopy (CV-AFS with a preconcentration factor greater than 250.

  13. A Geant4-based Simulation to Evaluate the Feasibility of Using Nuclear Resonance Fluorescence (NRF) in Determining Atomic Compositions of Body Tissue in Cancer Diagnostics and Irradiation

    Science.gov (United States)

    Gilbo, Yekaterina; Wijesooriya, Krishni; Liyanage, Nilanga

    2017-01-01

    Customarily applied in homeland security for identifying concealed explosives and chemical weapons, NRF (Nuclear Resonance Fluorescence) may have high potential in determining atomic compositions of body tissue. High energy photons incident on a target excite the target nuclei causing characteristic re-emission of resonance photons. As the nuclei of each isotope have well-defined excitation energies, NRF uniquely indicates the isotopic content of the target. NRF radiation corresponding to nuclear isotopes present in the human body is emitted during radiotherapy based on Bremsstrahlung photons generated in a linear electron accelerator. We have developed a Geant4 simulation in order to help assess NRF capabilities in detecting, mapping, and characterizing tumors. We have imported a digital phantom into the simulation using anatomical data linked to known chemical compositions of various tissues. Work is ongoing to implement the University of Virginia's cancer center treatment setup and patient geometry, and to collect and analyze the simulation's physics quantities to evaluate the potential of NRF for medical imaging applications. Preliminary results will be presented.

  14. Masking Agents Evaluation for Lead Determination by Flow Injection-Hydride Generation-Atomic Fluorescence Spectrometry Technique: Effect of KI, L-Cysteine, and 1,10-Phenanthroline

    Directory of Open Access Journals (Sweden)

    Blanca G. Beltrán

    2016-01-01

    Full Text Available Hydride generation (HG of lead technique presents interferences from foreign ions of complex matrix samples. In order to minimize these interferences, the effect of masking agents such as KI, L-cysteine, and 1,10-phenanthroline was studied in the absence and in the presence of selected interfering species (As, Cr, Cu, and Fe. Different modes of addition of masking agents were accomplished, that is, to either sample or KBH4 reducing solution. The lead determinations were performed using a flow injection analysis (FIA system coupled to HG and atomic fluorescence spectrometry (AFS. The linearity of calibration curves (1–10 μg Pb L−1 was not affected by the addition of the masking agents. The use of KI in the reducing solution diminished interferences from concentrations of As and Cu, while 1,10-phenanthroline showed a positive effect on the interference by As. Moreover, Cr and Cu appeared to be the most serious interfering ions for plumbane (PbH4, because they drastically reduced the analytical signal of lead. Fe did not present any interference under the employed experimental conditions, even at high levels. The accuracy was established through the analysis of certified reference material (i.e., BCR-610, groundwater using KI as masking agent. The detection limit reached by FIA-HG-AFS proposed methodology was 0.03 μg Pb L−1.

  15. Design and application of a novel integrated electrochemical hydride generation cell for the determination of arsenic in seaweeds by atomic fluorescence spectrometry.

    Science.gov (United States)

    Jiang, Xian-Juan; Gan, Wu-Er; Han, Su-Ping; Zi, Hong-Jing; He, You-Zhao

    2009-07-15

    An integrated electrochemical hydride generation cell, mainly composed of three components (a gas liquid separator, a graphite tube cathode and a reticulate Pt wire anode), was laboratory constructed and employed for the detection of arsenic by coupling to atomic fluorescence spectrometry. This integrated cell was free of ion-exchange membrane and individual anolyte, with the virtues of low-cost, easy assembly and environmental-friendly. Using flow injection mode, the sample throughput could come to 120 h(-1) attributed to the small dimension of the cathode chamber. The operating conditions for the electrochemical hydride generation of arsenic were investigated in detail and the potential interferences from oxygen or various ions were also evaluated. Under the optimized conditions, no obvious oxygen quenching effects were observed. The limit of detection of As (III) for the sample blank solution was 0.2 ng mL(-1) (3sigma) and the relative standard deviation was 3.1% for nine consecutive measurements of 5 ng mL(-1) As (III) standard solution. The calibration curve was linear up to 100 ng mL(-1). The accuracy of the method was verified by the determination of arsenic in the reference materials GBW08517 (Laminaria Japonica Aresch) and GBW10023 (Porphyra crispata) and the developed method was successfully applied to determine trace amounts of arsenic in edible seaweeds.

  16. Quantitative analysis of drug-induced complement-mediated cytotoxic effect on single tumor cells using atomic force microscopy and fluorescence microscopy.

    Science.gov (United States)

    Li, Mi; Liu, Lianqing; Xi, Ning; Wang, Yuechao; Xiao, Xiubin; Zhang, Weijing

    2015-01-01

    In the antibody-based targeted therapies of B-cell lymphomas, complement-mediated cytotoxicity (CMC) is an important mechanism. CMC is activated after the binding of drugs (monoclonal antibodies) to tumor cells. The activation of CMC ultimately leads to the lysis of tumor cells. However, it remains poorly understood how CMC alters the morphology and mechanics of single tumor cells at the nanoscale. In recent years, nanoscopic observations of cellular behaviors with the use of atomic force microscopy (AFM) have contributed much to the field of cell biology. In this work, by combining AFM with fluorescence microscopy, the detailed changes in cellular ultra-microstructures and mechanical properties during the process of CMC were quantitatively investigated on single tumor cells. AFM imaging distinctly showed that the CMC effect could lead to the formation of nano holes on the tumor cells. Quantitative analysis of AFM images indicated that cell surface became lower and rougher after the CMC process. The cellular mechanics measurements showed that during the process of CMC cells firstly softened and finally stiffened, which was validated by dynamically monitoring the mechanical changes of single living cells during CMC. The experimental results provide novel insights into the antibody-dependent CMC.

  17. Automated dispersive liquid-liquid microextraction coupled to high performance liquid chromatography - cold vapour atomic fluorescence spectroscopy for the determination of mercury species in natural water samples.

    Science.gov (United States)

    Liu, Yao-Min; Zhang, Feng-Ping; Jiao, Bao-Yu; Rao, Jin-Yu; Leng, Geng

    2017-04-14

    An automated, home-constructed, and low cost dispersive liquid-liquid microextraction (DLLME) device that directly coupled to a high performance liquid chromatography (HPLC) - cold vapour atomic fluorescence spectroscopy (CVAFS) system was designed and developed for the determination of trace concentrations of methylmercury (MeHg(+)), ethylmercury (EtHg(+)) and inorganic mercury (Hg(2+)) in natural waters. With a simple, miniaturized and efficient automated DLLME system, nanogram amounts of these mercury species were extracted from natural water samples and injected into a hyphenated HPLC-CVAFS for quantification. The complete analytical procedure, including chelation, extraction, phase separation, collection and injection of the extracts, as well as HPLC-CVAFS quantification, was automated. Key parameters, such as the type and volume of the chelation, extraction and dispersive solvent, aspiration speed, sample pH, salt effect and matrix effect, were thoroughly investigated. Under the optimum conditions, linear range was 10-1200ngL(-1) for EtHg(+) and 5-450ngL(-1) for MeHg(+) and Hg(2+). Limits of detection were 3.0ngL(-1) for EtHg(+) and 1.5ngL(-1) for MeHg(+) and Hg(2+). Reproducibility and recoveries were assessed by spiking three natural water samples with different Hg concentrations, giving recoveries from 88.4-96.1%, and relative standard deviations <5.1%. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Slurry sampling-microwave assisted leaching prior to hydride generation-pervaporation-atomic fluorescence detection for the determination of extractable arsenic in soil.

    Science.gov (United States)

    Caballo-López, A; Luque De Castro, M D

    2003-05-01

    A flow injection-pervaporation method, where the sample was introduced as slurry, has been developed for the continuous derivatization and determination of arsenic in soil by hydride generation-atomic fluorescence spectrometry. The removal of arsenic is achieved with the help of a microwave digestor, which facilitates an on-line leaching in the flow injection manifold. Slurries, prepared by mixing the soil (particle size <65 microm) with 6 mol L(-)(1) HCl, were magnetically stirred for 3 min, and while stirring, the pump aspirated the aliquot and filled the loop (500 microL) of the injection valve. An industrial soil and five types of soil (sandy, clayey, slimy, limy, organic) were selected for the optimization of the leaching and determination steps of arsenic, respectively. The results obtained from three certified reference materials [stream sediment GBW 07311 (188 microg/mL As), river sediment CRM 320 (76.7 microg/mL As), and soil GBW 07405 (412 microg/mL As)] using direct calibration against aqueous standards demonstrate the reliability of the method. The relative standard deviation for within-laboratory reproducibility was 4.5%.

  19. Multivariate optimization of a method for antimony determination by hydride generation atomic fluorescence spectrometry in hair samples of patients undergoing chemotherapy against Leishmaniasis.

    Science.gov (United States)

    Cardozo, Manuelle C; Cavalcante, Dannuza D; Silva, Daniel L F; Santos, Walter N L Dos; Bezerra, Marcos A

    2016-09-01

    A method was developed for determination of total antimony in hair samples from patients undergoing chemotherapy against Leishmaniasis based on the administration of pentavalent antimonial drugs. The method is based on microwave assisted digestion of the samples in a pressurized system, reduction of Sb5+ to Sb3+ with KI solution (10% w/v) in ascorbic acid (2%, w/v) and its subsequent determination by hydride generation atomic fluorescence spectrometry (HG-AFS). The proportions of each component (HCl, HNO3 and water) used in the digestion were studied applying a constrained mixtures design. The optimal proportions found were 50% water, 25% HNO3 and 25% HCl. Variables involved in the generation of antimony hydride were optimized using a Doehlert design revealing that good sensitivity is found when using 2.0% w/v NaBH4 and 4.4 mol L-1 HCl. Under the optimum experimental conditions, the method allows the determination of antimony in hair samples with detection and quantification limits of 1.4 and 4.6 ng g-1, respectively, and precision expressed as relative standard deviation (RSD) of 2.8% (n = 10 to 10.0 mg L-1). The developed method was applied in the analysis of hair samples from patients who take medication against Leishmaniasis.

  20. Multivariate optimization of a method for antimony determination by hydride generation atomic fluorescence spectrometry in hair samples of patients undergoing chemotherapy against Leishmaniasis

    Directory of Open Access Journals (Sweden)

    MANUELLE C. CARDOZO

    2016-01-01

    Full Text Available ABSTRACT A method was developed for determination of total antimony in hair samples from patients undergoing chemotherapy against Leishmaniasis based on the administration of pentavalent antimonial drugs. The method is based on microwave assisted digestion of the samples in a pressurized system, reduction of Sb5+ to Sb3+ with KI solution (10% w/v in ascorbic acid (2%, w/v and its subsequent determination by hydride generation atomic fluorescence spectrometry (HG-AFS. The proportions of each component (HCl, HNO3 and water used in the digestion were studied applying a constrained mixtures design. The optimal proportions found were 50% water, 25% HNO3 and 25% HCl. Variables involved in the generation of antimony hydride were optimized using a Doehlert design revealing that good sensitivity is found when using 2.0% w/v NaBH4 and 4.4 mol L-1 HCl. Under the optimum experimental conditions, the method allows the determination of antimony in hair samples with detection and quantification limits of 1.4 and 4.6 ng g-1, respectively, and precision expressed as relative standard deviation (RSD of 2.8% (n = 10 to 10.0 mg L-1. The developed method was applied in the analysis of hair samples from patients who take medication against Leishmaniasis.

  1. Absolute atomic oxygen density measurements for nanosecond-pulsed atmospheric-pressure plasma jets using two-photon absorption laser-induced fluorescence spectroscopy

    Science.gov (United States)

    Jiang, C.; Carter, C.

    2014-12-01

    Nanosecond-pulsed plasma jets that are generated under ambient air conditions and free from confinement of electrodes have become of great interest in recent years due to their promising applications in medicine and dentistry. Reactive oxygen species that are generated by nanosecond-pulsed, room-temperature non-equilibrium He-O2 plasma jets among others are believed to play an important role during the bactericidal or sterilization processes. We report here absolute measurements of atomic oxygen density in a 1 mm-diameter He/(1%)O2 plasma jet at atmospheric pressure using two-photon absorption laser-induced fluorescence spectroscopy. Oxygen number density on the order of 1013 cm-3 was obtained in a 150 ns, 6 kV single-pulsed plasma jet for an axial distance up to 5 mm above the device nozzle. Temporally resolved O density measurements showed that there are two maxima, separated in time by 60-70 µs, and a total pulse duration of 260-300 µs. Electrostatic modeling indicated that there are high-electric-field regions near the nozzle exit that may be responsible for the observed temporal behavior of the O production. Both the field-distribution-based estimation of the time interval for the O number density profile and a pulse-energy-dependence study confirmed that electric-field-dependent, direct and indirect electron-induced processes play important roles for O production.

  2. Determination of As(III) and As(V) in soils using sequential extraction combined with flow injection hydride generation atomic fluorescence detection

    Energy Technology Data Exchange (ETDEWEB)

    Shi Jianbo; Tang Zhiyong; Jin Zexiang; Chi Quan; He Bin; Jiang Guibin

    2003-01-27

    An analytical procedure for determination of As(III) and As(V) in soils using sequential extraction combined with flow injection (FI) hydride generation atomic fluorescence spectrometry (HG-AFS) was presented. The soils were sequentially extracted by water, 0.6 mol l{sup -1} KH{sub 2}PO{sub 4} solution, 1% (v/v) HCl solution and 1% (w/v) NaOH solution. The arsenite (As(III)) in extract was analyzed by HG-AFS in the medium of 0.1 mol l{sup -1} citric acid solution, then the total arsenic in extract was determined by HG-AFS using on-line reduction of arsenate with L-cysteine. The concentration of arsenate (As(V)) was calculated by the difference. The optimum conditions of extraction and determination were studied in detail. The detection limit (3{sigma}) for As(III) and As(V) were 0.11 and 0.07 {mu}g l{sup -1}, respectively. The relative standard deviation (R.S.D.) was 1.43% (n=11) at the 10 {mu}g l{sup -1} As level. The method was applied in the determination of As(III) and As(V) of real soils and the recoveries of As(III) and As(V) were in the range of 89.3-118 and 80.4-111%, respectively.

  3. Ultraviolet vapor generation atomic fluorescence spectrometric determination of mercury in natural water with enrichment by on-line solid phase extraction

    Science.gov (United States)

    Qin, Deyuan; Gao, Feng; Zhang, Zhaohui; Zhao, Liqian; Liu, Jixin; Ye, Jianping; Li, Junwei; Zheng, Fengxi

    2013-10-01

    A novel method, which coupled an on-line solid phase extraction (SPE) enrichment with ultraviolet vapor generation (UVG) atomic fluorescence spectrometry (AFS), was developed to improve the sensitivity of mercury determination and to remove the interference of some anion and organics to UVG of mercury. A high mercury retention efficiency and maximum exclusion of inorganic and organic matrix in water samples were achieved by using C18 SPE mini cartridge modified with sodium diethyldithiocarbamate (DDTC). Fast and efficient elution from the cartridge was found by using L-cysteine mixing solution. Furthermore, through the investigation of different UV reactor designs, the most important factor was the structure of the reactor (which corresponded roughly to the photon flux) wherein the tubing was sintered into the UV lamp to give the highest UV generation efficiency. The second factor was the materials of the tubing (which roughly corresponded to the working wavelength). Synthetic quartz, characterized by the highest transparency at 185 nm, attained the highest UVG efficiency, suggesting that the most favorable wavelength for UVG was 185 nm. Under optimum conditions, the achievable detection limit (3σ) with sample loadings of 10.0 mL was 0.03 ng L- 1 and 0.08 ng L- 1 with different manifolds, respectively. The method was successfully applied to the determination of Hg in tap water, river water and lake water samples.

  4. Distribution of heavy metals in Lumbricus terrestris, Aporrectodea longa and A. rosea measured by atomic absorption and X-ray fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, C.; Laursen, J. (Kongelige Veterinaer- og Landbohoejskole, Copenhagen (Denmark))

    1982-01-01

    Distribution of Ca, Pb, Cd, Zn, Fe and Mn has been investigated in the earthworm species Lumbricus terrestris, Aporectodea longa and A. rosea by atomic absorption and X-ray fluorescence spectrometry measurements. The material of L. terrestris originated from the garden of the Royal Veterinary and Agricultural University in central Copenhagen. Material of the other two species was sampled in sewage sludge treated plots. It was found that lead and cadmium are accumulated in the gut wall and from here transferred to waste nodules (brown bodies). In L. terrestris more lead was transferred to waste nodules than cadmium. Also large amounts of zinc were accumulated in the gut wall. Analyses of L. terrestris calciferous glands showed that these take part in regulation and excretion of a number of heavy metals. Lead and cadmium content was low in the ventral nerve chord and seminal vesicles. A. longa with poorly developed calciferous glands seems to rely more on waste nodule formation in the ultimate immobilization of lead.

  5. Speciation of inorganic- and methyl-mercury in biological matrixes by electrochemical vapor generation from an L-cysteine modified graphite electrode with atomic fluorescence spectrometry detection.

    Science.gov (United States)

    Zhang, Wang-Bing; Yang, Xin-An; Dong, Yong-Ping; Xue, Jing-Jing

    2012-11-06

    A novel nonchromatographic speciation technique for ultratrace inorganic mercury (Hg(2+)) and methylmercury (CH(3)Hg(+)) in biological materials is developed and validated by electrolytic vapor generation (EVG) coupled with atomic fluorescence spectrometry (AFS). The studies show that CH(3)Hg(+) and Hg(2+) can be converted to Hg vapor efficiently on an l-cysteine modified graphite cathode, which has never been reported before. We observe that only Hg(2+) can be converted efficiently to Hg vapor at low current mode (0.2 A). While at high current mode (2.2 A), both CH(3)Hg(+) and Hg(2+) can be reduced efficiently. As a result, we successfully establish an exact and sensitive method based on the current control to detect mercury speciation for the first time. The factors of electrolytic conditions have been optimized, and the potential mechanism is discussed. Under the optimal conditions, the detection limits (3s) of Hg(2+) and CH(3)Hg(+) in aqueous solutions are 0.098 and 0.073 μg L(-1), respectively. The relative standard deviations for 6 replicate determinations of 2 μg L(-1) Hg are determined as 3.2% and 4.7% for Hg(2+) and CH(3)Hg(+). The accuracy of the method is verified through the analysis of certified reference materials (CRM, NRC-DORM-2), and the proposed method has been applied satisfactorily to the determination of mercury speciation in several seafood samples by calibration curve mode.

  6. Determination of total Sb,Se Te, and Bi and evaluation of their inorganic species in garlic by hydride-generation-atomic-fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Matos Reyes, M.N.; Cervera, M.L.; Guardia, M. de la [University of Valencia, Department of Analytical Chemistry, Burjassot, Valencia (Spain)

    2009-07-15

    A sensitive and simple analytical method has been developed for determination of Sb(III), Sb(V), Se(IV), Se(VI), Te(IV), Te(VI), and Bi(III) in garlic samples by using hydride-generation-atomic-fluorescence spectrometry (HG-AFS). The method is based on a single extraction of the inorganic species by sonication at room temperature with 1 mol L{sup -1} H{sub 2}SO{sub 4} and washing of the solid phase with 0.1% (w/v) EDTA, followed by measurement of the corresponding hydrides generated under two different experimental conditions directly and after a pre-reduction step. The limit of detection of the method was 0.7 ng g{sup -1} for Sb(III), 1.0 ng g{sup -1} for Sb(V), 1.3 ng g{sup -1} for Se(IV), 1.0 ng g{sup -1} for Se(VI), 1.1 ng g{sup -1} for Te(IV), 0.5 ng g{sup -1} for Te(VI), and 0.9 ng g{sup -1} for Bi(III), in all cases expressed in terms of sample dry weight. (orig.)

  7. Fluorescence study of the effect of the oxidized phospholipids on amyloid fibril formation by the apolipoprotein A-I N-terminal fragment

    Science.gov (United States)

    Vus, Kateryna; Girych, Mykhailo; Trusova, Valeriya; Gorbenko, Galyna; Kinnunen, Paavo; Mizuguchi, Chiharu; Saito, Hiroyuki

    2017-11-01

    The effects of the oxidized phospholipids (oxPLs) on amyloid fibril formation by the apolipoprotein A-I variant 1-83/G26R have been investigated using Thioflavin T fluorescence assay. All types of the PoxnoPC assemblies (dispersions, micelles and lipid bilayer vesicles) induced retardation of amyloid nucleation and elongation and the enhancement of the 1-83/G26R fibrillization, although PazePC micelles completely prevented protein aggregation at low protein-to-lipid molar ratios. The ability of PazePC to inhibit 1-83/G26R aggregation was explained by the protein-lipid electrostatic interactions, which either stabilize the α-helical structure of the membrane-associated 1-83/G26R or facilitate the protein solubilization by the detergent micelles.

  8. Process Fragments

    Science.gov (United States)

    Eberle, Hanna; Unger, Tobias; Leymann, Frank

    The concepts presented in this paper are motivated by the assumption that process knowledge is distributed knowledge and not completely known just by one person. Driven by this assumption we deal in this paper with the following questions: How can partial process knowledge be represented? How can this partial knowledge be used to define something more complete? To use higher level artefacts as building blocks to new applications has a long tradition in software engineering to increase flexibility and reduce modeling costs. In this paper we take a first step in applying this concept to processes, by defining process building blocks and operations which compose process building blocks. The building blocks will be referred to as process fragments in the following. The process fragment composition may take place either at design or runtime of the process. The design time approach reduces design costs by reusing artefacts. However the runtime fragment composition approach realizes high flexibility due to the possibility in the dynamic selection of the fragments to be composed. The contribution of this work lies in a fragment definition that enables the fragment modeler to represent his 'local' and fragmentary knowledge in a formal way and which allows fragment models to be composed.

  9. Comparison of a portable micro-X-ray fluorescence spectrometry with inductively coupled plasma atomic emission spectrometry for the ancient ceramics analysis

    Energy Technology Data Exchange (ETDEWEB)

    Papadopoulou, D.N. [Laboratory of Analytical Chemistry, Faculty of Chemistry, Aristotle University, GR-54124, Thessaloniki (Greece); Zachariadis, G.A. [Laboratory of Analytical Chemistry, Faculty of Chemistry, Aristotle University, GR-54124, Thessaloniki (Greece); Anthemidis, A.N. [Laboratory of Analytical Chemistry, Faculty of Chemistry, Aristotle University, GR-54124, Thessaloniki (Greece); Tsirliganis, N.C. [Archaeometry Laboratory, Cultural and Educational Technology Institute, Tsimiski 58, GR-67100, Xanthi (Greece); Stratis, J.A. [Laboratory of Analytical Chemistry, Faculty of Chemistry, Aristotle University, GR-54124, Thessaloniki (Greece)]. E-mail: jstratis@chem.auth.gr

    2004-12-01

    Two multielement instrumental methods of analysis, micro X-ray fluorescence spectrometry (micro-XRF) and inductively coupled plasma atomic emission spectrometry (ICP-AES) were applied for the analysis of 7th and 5th century B.C. ancient ceramic sherds in order to evaluate the above two methods and to assess the potential to use the current compact and portable micro-XRF instrument for the in situ analysis of ancient ceramics. The distinguishing factor of interest is that micro-XRF spectrometry offers the possibility of a nondestructive analysis, an aspect of primary importance in the compositional analysis of cultural objects. Micro-XRF measurements were performed firstly directly on the ceramic sherds with no special pretreatment apart from surface cleaning (micro-XRF on sherds) and secondly on pressed pellet disks which were prepared for each ceramic sherd (micro-XRF on pellet). For the ICP-AES determination of elements, test solutions were prepared by the application of a microwave-assisted decomposition procedure in closed high-pressure PFA vessels. Also, the standard reference material SARM 69 was used for the efficiency calibration of the micro-XRF instrument and was analysed by both methods. In order to verify the calibration, the standard reference materials NCS DC 73332 and SRM620 as well as the reference materials AWI-1 and PRI-1 were analysed by micro-XRF. Elemental concentrations determined by the three analytical procedures (ICP-AES, micro-XRF on sherds and micro-XRF on pellets) were statistically treated by correlation analysis and Student's t-test (at the 95% confidence level)

  10. Ultraviolet vapor generation atomic fluorescence spectrometric determination of mercury in natural water with enrichment by on-line solid phase extraction

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Deyuan [Beijing Titan Instruments Co., Ltd., Beijing 100015 (China); Gao, Feng; Zhang, Zhaohui [Beijing Entry–Exit Inspection and Quarantine Bureau, Beijing 100026 (China); Zhao, Liqian [Beijing Titan Instruments Co., Ltd., Beijing 100015 (China); Liu, Jixin, E-mail: ljx2117@gmail.com [Beijing Titan Instruments Co., Ltd., Beijing 100015 (China); Ye, Jianping; Li, Junwei; Zheng, Fengxi [Beijing Titan Instruments Co., Ltd., Beijing 100015 (China)

    2013-10-01

    A novel method, which coupled an on-line solid phase extraction (SPE) enrichment with ultraviolet vapor generation (UVG) atomic fluorescence spectrometry (AFS), was developed to improve the sensitivity of mercury determination and to remove the interference of some anion and organics to UVG of mercury. A high mercury retention efficiency and maximum exclusion of inorganic and organic matrix in water samples were achieved by using C{sub 18} SPE mini cartridge modified with sodium diethyldithiocarbamate (DDTC). Fast and efficient elution from the cartridge was found by using L-cysteine mixing solution. Furthermore, through the investigation of different UV reactor designs, the most important factor was the structure of the reactor (which corresponded roughly to the photon flux) wherein the tubing was sintered into the UV lamp to give the highest UV generation efficiency. The second factor was the materials of the tubing (which roughly corresponded to the working wavelength). Synthetic quartz, characterized by the highest transparency at 185 nm, attained the highest UVG efficiency, suggesting that the most favorable wavelength for UVG was 185 nm. Under optimum conditions, the achievable detection limit (3σ) with sample loadings of 10.0 mL was 0.03 ng L{sup −1} and 0.08 ng L{sup −1} with different manifolds, respectively. The method was successfully applied to the determination of Hg in tap water, river water and lake water samples. - Graphical abstract: An interference free ultraviolet vapor generation based method was applied to determine ultratrace mercury in water sample. - Highlights: • Hg was enriched by on-line solid phase extraction. • Hg was detected by ultraviolet vapor generation AFS. • The interference of some anion and some organics was removed. • The effects of details of UV set were systemically discussed.

  11. Determination of inorganic arsenic in algae using bromine halogenation and on-line nonpolar solid phase extraction followed by hydride generation atomic fluorescence spectrometry.

    Science.gov (United States)

    Zhang, Weihong; Qi, Yuehan; Qin, Deyuan; Liu, Jixin; Mao, Xuefei; Chen, Guoying; Wei, Chao; Qian, Yongzhong

    2017-08-01

    Accurate, stable and fast analysis of toxic inorganic arsenic (iAs) in complicated and arsenosugar-rich algae matrix is always a challenge. Herein, a novel analytical method for iAs in algae was reported, using bromine halogenation and on-line nonpolar solid phase extraction (SPE) followed by hydride generation atomic fluorescence spectrometry (HG-AFS). The separation of iAs from algae was first performed by nonpolar SPE sorbent using Br - for arsenic halogenation. Algae samples were extracted with 1% perchloric acid. Then, 1.5mL extract was reduced by 1% thiourea, and simultaneously reacted (for 30min) with 50μL of 10% KBr for converting iAs to AsBr 3 after adding 3.5mL of 70% HCl to 5mL. A polystyrene (PS) resin cartridge was employed to retain arsenicals, which were hydrolyzed, eluted from the PS resin with H 2 O, and categorized as iAs. The total iAs was quantified by HG-AFS. Under optimum conditions, the spiked recoveries of iAs in real algae samples were in the 82-96% range, and the method achieved a desirable limit of detection of 3μgkg -1 . The inter-day relative standard deviations were 4.5% and 4.1% for spiked 100 and 500μgkg -1 respectively, which proved acceptable for this method. For real algae samples analysis, the highest presence of iAs was found in sargassum fusiforme, followed by kelp, seaweed and laver. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Arsenic fractionation in agricultural soil using an automated three-step sequential extraction method coupled to hydride generation-atomic fluorescence spectrometry.

    Science.gov (United States)

    Rosas-Castor, J M; Portugal, L; Ferrer, L; Guzmán-Mar, J L; Hernández-Ramírez, A; Cerdà, V; Hinojosa-Reyes, L

    2015-05-18

    A fully automated modified three-step BCR flow-through sequential extraction method was developed for the fractionation of the arsenic (As) content from agricultural soil based on a multi-syringe flow injection analysis (MSFIA) system coupled to hydride generation-atomic fluorescence spectrometry (HG-AFS). Critical parameters that affect the performance of the automated system were optimized by exploiting a multivariate approach using a Doehlert design. The validation of the flow-based modified-BCR method was carried out by comparison with the conventional BCR method. Thus, the total As content was determined in the following three fractions: fraction 1 (F1), the acid-soluble or interchangeable fraction; fraction 2 (F2), the reducible fraction; and fraction 3 (F3), the oxidizable fraction. The limits of detection (LOD) were 4.0, 3.4, and 23.6 μg L(-1) for F1, F2, and F3, respectively. A wide working concentration range was obtained for the analysis of each fraction, i.e., 0.013-0.800, 0.011-0.900 and 0.079-1.400 mg L(-1) for F1, F2, and F3, respectively. The precision of the automated MSFIA-HG-AFS system, expressed as the relative standard deviation (RSD), was evaluated for a 200 μg L(-1) As standard solution, and RSD values between 5 and 8% were achieved for the three BCR fractions. The new modified three-step BCR flow-based sequential extraction method was satisfactorily applied for arsenic fractionation in real agricultural soil samples from an arsenic-contaminated mining zone to evaluate its extractability. The frequency of analysis of the proposed method was eight times higher than that of the conventional BCR method (6 vs 48 h), and the kinetics of lixiviation were established for each fraction. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Arsenic speciation based on ion exchange high-performance liquid chromatography hyphenated with hydride generation atomic fluorescence and on-line UV photo oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Bin He; Jiang Gui-bin; Xu Xiao-bai [Chinese Academy of Scinces, Beijing (China). Research Center for Eco-Environmental Sciences

    2000-12-01

    An on-line method capable of the separation of arsenic species was developed for the speciation of arsenite As(III), arsenate As(V), monomethylarsenic (MMA) and dimethylarsenic acid (DMA) in biological samples. The method is based on the combination of high-performance liquid chromatograph (HPLC) for separation, UV photo oxidation for sample digestion and hydride generation atomic fluorescence spectrometry (HGAFS) for sensitive detection. The best separation results were obtained with an anion-exchange AS11 column protected by an AG11 guard column, and gradient elution with NaH{sub 2}PO{sub 4} and water as mobile phase. The on-line UV photo oxidation with 1.5% K{sub 2}S{sub 2}O{sub 8} in 0.2 mol L{sup -1} NaOH in an 8 m PTFE coil for 40 s ensures the digestion of organoarsenic compounds. Detection limits for the four species were in the range of 0.11-0.15 ng (20 {mu}L injected). Procedures were validated by analysis of the certified reference materials GBW09103 freeze-dried human urine and the results were in good agreement with the certified values of total arsenic concentration. The method has been successfully applied to speciation studies of blood arsenic species with no need of sample pretreatment. Speciation of arsenic in blood samples collected from two patients after the ingestion of realgar-containing drug reveals slight increase of arsenite and DMA, resulting from the digestion of realgar. (orig.)

  14. Chameleon fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Brax, Philippe [Institut de Physique Théorique, CEA, IPhT, CNRS, URA 2306, F-91191Gif/Yvette Cedex (France); Upadhye, Amol, E-mail: philippe.brax@cea.fr, E-mail: aupadhye@anl.gov [Institute for the Early Universe, Ewha University, International Education, Building #601, 11-1, Daehyun-Dong Seodaemun-Gu, Seoul 120-750 (Korea, Republic of)

    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.

  15. Rock fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Brown, W.S.; Green, S.J.; Hakala, W.W.; Hustrulid, W.A.; Maurer, W.C. (eds.)

    1976-01-01

    Experts in rock mechanics, mining, excavation, drilling, tunneling and use of underground space met to discuss the relative merits of a wide variety of rock fragmentation schemes. Information is presented on novel rock fracturing techniques; tunneling using electron beams, thermocorer, electric spark drills, water jets, and diamond drills; and rock fracturing research needs for mining and underground construction. (LCL)

  16. Speciation analysis of mercury in sediments using vortex-assisted liquid-liquid microextraction coupled to high-performance liquid chromatography-cold vapor atomic fluorescence spectrometry.

    Science.gov (United States)

    Leng, Geng; Yin, Hui; Li, Shaobo; Chen, Yong; Dan, Dezhong

    2012-09-15

    A simple and fast solvent microextraction method termed vortex-assisted liquid-liquid microextraction (VALLME) coupled with high-performance liquid chromatography-vapor generation atomic fluorescence spectrometry (HPLC-CVAFS) has been developed for the trace analysis of methylmercury (MeHg(+)), ethylmercury (EtHg(+)) and inorganic mercury (Hg(2+)) in sediment samples. Carbon tetrachloride was used as collecting solvent for the extraction of mercury species from sediment by a vortex-assisted extraction. In VALLME, 100 μL 1% (m/v) l-Cysteine were used as extraction solvent and were injected into 4 mL carbon tetrachloride. The extraction solvent dispersed into carbon tetrachloride under vigorously shaking by a vortex agitator. The fine droplets could extract mercury species within few minutes because of the shorter diffusion distance and larger specific surface area. After centrifugation, the floating extractant phase restored its initial single microdrop shape and was used for HPLC-CVAFS analysis. The parameters affecting the extraction efficiency of the proposed VALLME such as extraction solvent, vortex time, volumes of extraction solvent and salt addition etc. were investigated. Under the optimum conditions, linearity was found in the concentration range from 0.1 to 25 ng g(-1) for MeHg(+), 0.2 to 65 ng g(-1) for EtHg(+), and 0.1 to 30 ng g(-1) for Hg(2+). Coefficients of determination (R(2)) ranged from 0.9938 to 0.9972. The limits of detection (LODs, signal-to-noise ratio (S/N)=3) were 0.028 ng g(-1) for MeHg(+), 0.057 ng g(-1) for EtHg(+), and 0.029 ng g(-1) for Hg(2+). Reproducibility and recoveries were assessed by testing a series of 6 sediment samples, which were spiked with different concentration levels. Finally, the proposed method was successfully applied in analyses of real nature sediment samples. In this work, VALLME was applied to the extraction of mercury species in sediment samples for the first time. Using l-Cys as extraction solvent, the

  17. Arsenic fractionation in agricultural soil using an automated three-step sequential extraction method coupled to hydride generation-atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Rosas-Castor, J.M. [Universidad Autónoma de Nuevo León, UANL, Facultad de Ciencias Químicas, Cd. Universitaria, San Nicolás de los Garza, Nuevo León, C.P. 66451 Nuevo León (Mexico); Group of Analytical Chemistry, Automation and Environment, University of Balearic Islands, Cra. Valldemossa km 7.5, 07122 Palma de Mallorca (Spain); Portugal, L.; Ferrer, L. [Group of Analytical Chemistry, Automation and Environment, University of Balearic Islands, Cra. Valldemossa km 7.5, 07122 Palma de Mallorca (Spain); Guzmán-Mar, J.L.; Hernández-Ramírez, A. [Universidad Autónoma de Nuevo León, UANL, Facultad de Ciencias Químicas, Cd. Universitaria, San Nicolás de los Garza, Nuevo León, C.P. 66451 Nuevo León (Mexico); Cerdà, V. [Group of Analytical Chemistry, Automation and Environment, University of Balearic Islands, Cra. Valldemossa km 7.5, 07122 Palma de Mallorca (Spain); Hinojosa-Reyes, L., E-mail: laura.hinojosary@uanl.edu.mx [Universidad Autónoma de Nuevo León, UANL, Facultad de Ciencias Químicas, Cd. Universitaria, San Nicolás de los Garza, Nuevo León, C.P. 66451 Nuevo León (Mexico)

    2015-05-18

    Highlights: • A fully automated flow-based modified-BCR extraction method was developed to evaluate the extractable As of soil. • The MSFIA–HG-AFS system included an UV photo-oxidation step for organic species degradation. • The accuracy and precision of the proposed method were found satisfactory. • The time analysis can be reduced up to eight times by using the proposed flow-based BCR method. • The labile As (F1 + F2) was <50% of total As in soil samples from As-contaminated-mining zones. - Abstract: A fully automated modified three-step BCR flow-through sequential extraction method was developed for the fractionation of the arsenic (As) content from agricultural soil based on a multi-syringe flow injection analysis (MSFIA) system coupled to hydride generation-atomic fluorescence spectrometry (HG-AFS). Critical parameters that affect the performance of the automated system were optimized by exploiting a multivariate approach using a Doehlert design. The validation of the flow-based modified-BCR method was carried out by comparison with the conventional BCR method. Thus, the total As content was determined in the following three fractions: fraction 1 (F1), the acid-soluble or interchangeable fraction; fraction 2 (F2), the reducible fraction; and fraction 3 (F3), the oxidizable fraction. The limits of detection (LOD) were 4.0, 3.4, and 23.6 μg L{sup −1} for F1, F2, and F3, respectively. A wide working concentration range was obtained for the analysis of each fraction, i.e., 0.013–0.800, 0.011–0.900 and 0.079–1.400 mg L{sup −1} for F1, F2, and F3, respectively. The precision of the automated MSFIA–HG-AFS system, expressed as the relative standard deviation (RSD), was evaluated for a 200 μg L{sup −1} As standard solution, and RSD values between 5 and 8% were achieved for the three BCR fractions. The new modified three-step BCR flow-based sequential extraction method was satisfactorily applied for arsenic fractionation in real agricultural

  18. Determination of hydrogen sulfide and volatile thiols in air samples by mercury probe derivatization coupled with liquid chromatography-atomic fluorescence spectrometry.

    Science.gov (United States)

    Bramanti, Emilia; D'Ulivo, Lucia; Lomonte, Cristina; Onor, Massimo; Zamboni, Roberto; Raspi, Giorgio; D'Ulivo, Alessandro

    2006-10-02

    A new procedure is proposed for the sampling and storage of hydrogen sulphide (H2S) and volatile thiols (methanethiol or methyl mercaptan, ethanethiol and propanethiol) for their determination by liquid chromatography. The sampling procedure is based on the trapping/pre-concentration of the analytes in alkaline aqueous solution containing an organic mercurial probe p-hydroxymercurybenzoate, HO-Hg-C6H4-COO- (PHMB), where they are derivatized to stable PHMB complexes based on mercury-sulfur covalent bonds. PHMB complexes are separated on a C18 reverse phase column, allowing their determination by liquid chromatography coupled with sequential non-selective UV-vis (DAD) and mercury specific (chemical vapor generation atomic fluorescence spectrometry, CVGAFS) on-line detectors. PHMB complexes, S(PHMB)2CH3S-PHMB, C2H5S-PHMB and C3H7S-PHMB, are stable alt least for 12 h at room temperature and for 3 months if stored frozen (-20 degrees C). The best analytical figures of merits in the optimized conditions were obtained by CVGAFS detection, with detection limits (LODc) of 9.7 microg L(-1) for H2S, 13.7 microg L(-1) for CH(3)SH, 17.7 microg L(-1) for C2H5SH and 21.7 microg L(-1) for C3H7SH in the trapping solution in form of RS-PHMB complexes, the relative standard deviation (R.S.D.) ranging between 1.0 and 1.5%, and a linear dynamic range (LDR) between 10 and 9700 microg L(-1). Conventional UV absorbance detectors tuned at 254 nm can be employed as well with comparable R.S.D. and LDR, but with LODc one order of magnitude higher than AFS detector and lower specificity. The sampling procedure followed by LC-DAD-CVGAFS analysis has been validated, as example, for H2S determination by a certified gas permeation tube as a source of 3.071+/-0.154 microg min(-1) of H2S, giving a recovery of 99.8+/-7% and it has been applied to the determination of sulfur compounds in real gas samples (biogas and the air of a plant for fractional distillation of crude oil).

  19. Investigation of Al{sub 2}O{sub 3} barrier film properties made by atomic layer deposition onto fluorescent tris-(8-hydroxyquinoline) aluminium molecular films

    Energy Technology Data Exchange (ETDEWEB)

    Maindron, Tony; Aventurier, Bernard [LETI/DOPT/SCOOP/Laboratoire des Composants pour la Visualisation, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Ghazouani, Ahlem; Jullien, Tony [LETI/DTSI/SDEP/Laboratoire Dépôt Equipe 2, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Rochat, Névine [LETI/DTSI/Service de Caractérisation des Matériaux et Composants, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Simon, Jean-Yves; Viasnoff, Emilie [LETI/DOPT/SCOOP/Laboratoire des Composants pour la Visualisation, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France)

    2013-12-02

    Al{sub 2}O{sub 3} films have been deposited at 85 °C by atomic layer deposition onto single 100 nm thick tris-(8-hydroxyquinoline) aluminium (AlQ{sub 3}) films made onto silicon wafers. It has been found that a thick ALD-deposited Al{sub 2}O{sub 3} layer (> 11 nm) greatly prevents the photo-oxidation of AlQ{sub 3} films when exposed to continuous UV irradiation (350 mW/cm{sup 2}). Thin Al{sub 2}O{sub 3} thicknesses (< 11 nm) on the contrary yield lower barrier performances. Defects in the Al{sub 2}O{sub 3} layer have been easily observed as non-fluorescent AlQ{sub 3} singularities, or black spots, under UV light on the system Si/AlQ{sub 3}/Al{sub 2}O{sub 3} stored into laboratory conditions (22 °C/50% Relative Humidity (RH)) for long time scale (∼ 2000 h). Accelerated aging conditions in a climatic chamber (85 °C/85% RH) also allow faster visualization of the same defects (168 h). The black spot density grows upon time and the black spot density occurrence rates have been calculated to be 0.024 h{sup −1}·cm{sup −2} and 0.243 h{sup −1}·cm{sup −2} respectively for the two testing conditions. A detailed investigation of these defects did show that they cannot be ascribed to the presence of a detectable particle. In that sense they are presumably the consequence of the existence of nanometre-scaled defects which cannot be detected onto fresh samples. Interestingly, an additional overcoating of ebeam-deposited SiO{sub 2} onto the Si/AlQ{sub 3}/Al{sub 2}O{sub 3} sample helps to decrease drastically the black spot density occurrence rates down to 0.004 h{sup −1}·cm{sup −2} and 0.04 h{sup −1}·cm{sup −2} respectively for 22 °C/50% RH and 85 °C/85% RH testing conditions. These observations highlight the moisture sensitivity of low temperature ALD-deposited Al{sub 2}O{sub 3} films and confirm the general idea that a single Al{sub 2}O{sub 3} ALD film performs as an ultra-high barrier but needs to be overprotected from water condensation by an

  20. Optical diagnostics of radio-frequency plasmas containing CHF3 and CHF3/O2: Laser-induced fluorescence of CF2, CF, and O atoms, and optical emission from H, F, and O

    Science.gov (United States)

    Hancock, G.; Sucksmith, J. P.

    2002-01-01

    Laser-induced fluorescence (LIF) has been used to measure absolute concentrations of CF2, CF, and O atoms in a parallel-plate capacitatively coupled radio-frequency-driven plasma containing CHF3 and its mixtures with Ar and O2 at pressures between 50 and 500 mTorr. In CHF3 the spatial distribution of CF2 peaks at the driven electrode, and shows the importance of surface processes for its production. Time-resolved studies show evidence for its homogeneous chemical removal. CF concentrations are an order of magnitude lower than those of CF2, and removal by reaction with H atoms is consistent with time-resolved data taken on plasma extinction. For both radicals the absolute concentrations are higher than those found for similar plasmas in CF4. In the presence of O2 the fluorinated radical concentrations drop to below the detection limit, and the influence of surface removal processes is again invoked to explain the increase in O atom concentration observed when a small amount of CHF3 is added to a dominantly O2 gas flow. Optical emission from excited F, H, and O atoms is observed, and even when corrected by actinometry, is shown to be an unreliable indicator of the relative concentration of the ground-state species because of contributions from dissociative excitation of stable species in the discharge. Excited H atoms are found to be translationally hot from measurements of their linewidths, and are clearly not all formed from excitation of H atoms. Time-resolved actinometry (TRA) can be used in some cases to remove the contribution to the emission from dissociative excitation, but in the case of O atoms where both LIF and TRA were compared, the influence of a time-dependent dissociative excitation step complicates the analysis and is attributed to the presence of other species such as O2(a1Δg) in the discharge.

  1. Bespoke Fragments

    DEFF Research Database (Denmark)

    Kruse Aagaard, Anders

    2017-01-01

    The PhD project Bespoke Fragments is investigating the space emerging in the exploration of the relationship between digital drawing and fabrication, and the field of materials and their properties and capacities. Through a series of different experiments, the project situates itself in a shuttling...... tangible experiments, the project discusses materiality and digitally controlled fabrication tools as a expansion of the architect’s tool box and workflow. Bespoke Fragments considers this expansion as an opportunity to establish a connection between forms of digital drawing and the specificities...... of materials. Through that connection, the project seeks to use the realisation to generate developments and findings and, through an iterative mode of thinking, establish a dialogue between drawing, materials, and fabrication. The use of digital fabrication tools through digital drawing opens up a new...

  2. Architectural fragments

    DEFF Research Database (Denmark)

    Bang, Jacob Sebastian

    2018-01-01

    . I try to invent the ways of drawing the models - that decode and unfold them into architectural fragments- into future buildings or constructions in the landscape. [1] Luigi Moretti: Italian architect, 1907 - 1973 [2] Man Ray: American artist, 1890 - 1976. in 2015, I saw the wonderful exhibition......I have created a large collection of plaster models: a collection of Obstructions, errors and opportunities that may develop into architecture. The models are fragments of different complex shapes as well as more simple circular models with different profiling and diameters. In this contect I have...... been studying Luigi Moretti's [1] plastermodel - "the Model of the inner spaces of the Saint Maria of the Divine Providence" - in which context I see my own models. In 1934, Man Ray [2] photographed mathematical rmodels (in plaster) at the Henri Poincaré Institute in Paris and later used...

  3. PubChem atom environments.

    Science.gov (United States)

    Hähnke, Volker D; Bolton, Evan E; Bryant, Stephen H

    2015-01-01

    Atom environments and fragments find wide-spread use in chemical information and cheminformatics. They are the basis of prediction models, an integral part in similarity searching, and employed in structure search techniques. Most of these methods were developed and evaluated on the relatively small sets of chemical structures available at the time. An analysis of fragment distributions representative of most known chemical structures was published in the 1970s using the Chemical Abstracts Service data system. More recently, advances in automated synthesis of chemicals allow millions of chemicals to be synthesized by a single organization. In addition, open chemical databases are readily available containing tens of millions of chemical structures from a multitude of data sources, including chemical vendors, patents, and the scientific literature, making it possible for scientists to readily access most known chemical structures. With this availability of information, one can now address interesting questions, such as: what chemical fragments are known today? How do these fragments compare to earlier studies? How unique are chemical fragments found in chemical structures? For our analysis, after hydrogen suppression, atoms were characterized by atomic number, formal charge, implicit hydrogen count, explicit degree (number of neighbors), valence (bond order sum), and aromaticity. Bonds were differentiated as single, double, triple or aromatic bonds. Atom environments were created in a circular manner focused on a central atom with radii from 0 (atom types) up to 3 (representative of ECFP_6 fragments). In total, combining atom types and atom environments that include up to three spheres of nearest neighbors, our investigation identified 28,462,319 unique fragments in the 46 million structures found in the PubChem Compound database as of January 2013. We could identify several factors inflating the number of environments involving transition metals, with many

  4. Methodology using a portable X-ray fluorescence device for on-site and rapid evaluation of heavy-atom contamination in wounds: a model study for application to plutonium contamination.

    Directory of Open Access Journals (Sweden)

    Hiroshi Yoshii

    Full Text Available Workers decommissioning the Fukushima-Daiichi nuclear power plant damaged from the Great East Japan Earthquake and resulting tsunami are at risk of injury with possible contamination from radioactive heavy atoms including actinides, such as plutonium. We propose a new methodology for on-site and rapid evaluation of heavy-atom contamination in wounds using a portable X-ray fluorescence (XRF device. In the present study, stable lead was used as the model contaminant substitute for radioactive heavy atoms. First, the wound model was developed by placing a liquid blood phantom on an epoxy resin wound phantom contaminated with lead. Next, the correlation between the concentration of contaminant and the XRF peak intensity was formulated considering the thickness of blood exiting the wound. Methods to determine the minimum detection limit (MDL of contaminants at any maximal equivalent dose to the wound by XRF measurement were also established. For example, in this system, at a maximal equivalent dose of 16.5 mSv to the wound and blood thickness of 0.5 mm, the MDL value for lead was 1.2 ppm (3.1 nmol. The radioactivity of 239Pu corresponding to 3.1 nmol is 1.7 kBq, which is lower than the radioactivity of 239Pu contaminating puncture wounds in previous severe accidents. In conclusion, the established methodology could be beneficial for future development of a method to evaluate plutonium contamination in wounds. Highlights: Methodology for evaluation of heavy-atom contamination in a wound was established. A portable X-ray fluorescence device enables on-site, rapid and direct evaluation. This method is expected to be used for evaluation of plutonium contamination in wounds.

  5. Methodology using a portable X-ray fluorescence device for on-site and rapid evaluation of heavy-atom contamination in wounds: a model study for application to plutonium contamination.

    Science.gov (United States)

    Yoshii, Hiroshi; Yanagihara, Kouta; Imaseki, Hitoshi; Hamano, Tsuyoshi; Yamanishi, Hirokuni; Inagaki, Masayo; Sakai, Yasuhiro; Sugiura, Nobuyuki; Kurihara, Osamu; Sakai, Kazuo

    2014-01-01

    Workers decommissioning the Fukushima-Daiichi nuclear power plant damaged from the Great East Japan Earthquake and resulting tsunami are at risk of injury with possible contamination from radioactive heavy atoms including actinides, such as plutonium. We propose a new methodology for on-site and rapid evaluation of heavy-atom contamination in wounds using a portable X-ray fluorescence (XRF) device. In the present study, stable lead was used as the model contaminant substitute for radioactive heavy atoms. First, the wound model was developed by placing a liquid blood phantom on an epoxy resin wound phantom contaminated with lead. Next, the correlation between the concentration of contaminant and the XRF peak intensity was formulated considering the thickness of blood exiting the wound. Methods to determine the minimum detection limit (MDL) of contaminants at any maximal equivalent dose to the wound by XRF measurement were also established. For example, in this system, at a maximal equivalent dose of 16.5 mSv to the wound and blood thickness of 0.5 mm, the MDL value for lead was 1.2 ppm (3.1 nmol). The radioactivity of 239Pu corresponding to 3.1 nmol is 1.7 kBq, which is lower than the radioactivity of 239Pu contaminating puncture wounds in previous severe accidents. In conclusion, the established methodology could be beneficial for future development of a method to evaluate plutonium contamination in wounds. Highlights: Methodology for evaluation of heavy-atom contamination in a wound was established. A portable X-ray fluorescence device enables on-site, rapid and direct evaluation. This method is expected to be used for evaluation of plutonium contamination in wounds.

  6. Fragmentation based

    Directory of Open Access Journals (Sweden)

    Shashank Srivastava

    2014-01-01

    Gaining the understanding of mobile agent architecture and the security concerns, in this paper, we proposed a security protocol which addresses security with mitigated computational cost. The protocol is a combination of self decryption, co-operation and obfuscation technique. To circumvent the risk of malicious code execution in attacking environment, we have proposed fragmentation based encryption technique. Our encryption technique suits the general mobile agent size and provides hard and thorny obfuscation increasing attacker’s challenge on the same plane providing better performance with respect to computational cost as compared to existing AES encryption.

  7. Mercury speciation by high-performance liquid chromatography atomic fluorescence spectrometry using an integrated microwave/UV interface. Optimization of a single step procedure for the simultaneous photo-oxidation of mercury species and photo-generation of Hg0

    Science.gov (United States)

    de Quadros, Daiane P. C.; Campanella, Beatrice; Onor, Massimo; Bramanti, Emilia; Borges, Daniel L. G.; D'Ulivo, Alessandro

    2014-11-01

    We described the hyphenation of photo-induced chemical vapor generation with high performance liquid chromatography-atomic fluorescence spectrometry (HPLC-AFS) for the quantification of inorganic mercury, methylmercury (MeHg) and ethylmercury (EtHg). In the developed procedure, formic acid in mobile phase was used for the photodecomposition of organomercury compounds and reduction of Hg2 + to mercury vapor under microwave/ultraviolet (MW/UV) irradiation. We optimized the proposed method studying the influence of several operating parameters, including the type of organic acid and its concentration, MW power, composition of HPLC mobile phase and catalytic action of TiO2 nanoparticles. Under the optimized conditions, the limits of detection were 0.15, 0.15 and 0.35 μg L- 1 for inorganic mercury, MeHg and EtHg, respectively. The developed method was validated by determination of the main analytical figures of merit and applied to the analysis of three certified reference materials. The online interfacing of liquid chromatography with photochemical-vapor generation-atomic fluorescence for mercury determination is simple, environmentally friendly, and represents an attractive alternative to the conventional tetrahydroborate (THB) system.

  8. Photolysis of CH{sub 3}CHO at 248 nm: Evidence of triple fragmentation from primary quantum yield of CH{sub 3} and HCO radicals and H atoms

    Energy Technology Data Exchange (ETDEWEB)

    Morajkar, Pranay; Schoemaecker, Coralie; Fittschen, Christa, E-mail: christa.fittschen@univ-lille1.fr [Université Lille Nord de France, PhysicoChimie des Processus de Combustion et de l’Atmosphère – PC2A, UMR 8522, F-59650 Villeneuve d’Ascq (France); Bossolasco, Adriana [Université Lille Nord de France, PhysicoChimie des Processus de Combustion et de l’Atmosphère – PC2A, UMR 8522, F-59650 Villeneuve d’Ascq (France); INFIQC (CONICET), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba (Argentina)

    2014-06-07

    Radical quantum yields have been measured following the 248 nm photolysis of acetaldehyde, CH{sub 3}CHO. HCO radical and H atom yields have been quantified by time resolved continuous wave Cavity Ring Down Spectroscopy in the near infrared following their conversion to HO{sub 2} radicals by reaction with O{sub 2}. The CH{sub 3} radical yield has been determined using the same technique following their conversion into CH{sub 3}O{sub 2}. Absolute yields have been deduced for HCO radicals and H atoms through fitting of time resolved HO{sub 2} profiles, obtained under various O{sub 2} concentrations, to a complex model, while the CH{sub 3} yield has been determined relative to the CH{sub 3} yield from 248 nm photolysis of CH{sub 3}I. Time resolved HO{sub 2} profiles under very low O{sub 2} concentrations suggest that another unknown HO{sub 2} forming reaction path exists in this reaction system besides the conversion of HCO radicals and H atoms by reaction with O{sub 2}. HO{sub 2} profiles can be well reproduced under a large range of experimental conditions with the following quantum yields: CH{sub 3}CHO + hν{sub 248nm} → CH{sub 3}CHO{sup *}, CH{sub 3}CHO{sup *} → CH{sub 3} + HCO ϕ{sub 1a} = 0.125 ± 0.03, CH{sub 3}CHO{sup *} → CH{sub 3} + H + CO ϕ{sub 1e} = 0.205 ± 0.04, CH{sub 3}CHO{sup *}→{sup o{sub 2}}CH{sub 3}CO + HO{sub 2} ϕ{sub 1f} = 0.07 ± 0.01. The CH{sub 3}O{sub 2} quantum yield has been determined in separate experiments as ϕ{sub CH{sub 3}} = 0.33 ± 0.03 and is in excellent agreement with the CH{sub 3} yields derived from the HO{sub 2} measurements considering that the triple fragmentation (R1e) is an important reaction path in the 248 nm photolysis of CH{sub 3}CHO. From arithmetic considerations taking into account the HO{sub 2} and CH{sub 3} measurements we deduce a remaining quantum yield for the molecular pathway: CH{sub 3}CHO{sup *} → CH{sub 4} + CO ϕ{sub 1b} = 0.6. All experiments can be

  9. Bespoke Fragments

    DEFF Research Database (Denmark)

    Kruse Aagaard, Anders

    2016-01-01

    the digital environment with the reality of materials – and use realisation and materialisation to generate architectural developments and findings through an iterative mode of thinking about the dialogue between drawing, materials and fabrication. The control of fabrication tools through digital drawing......The Ph.D. -project Bespoke Fragments seeks to explore and utilise the space emerging between the potentials of digital drawing and fabrication and the field of materials and their properties and capacities. Within this span, the project is situated in a shuttling between the virtual and the actual......, investigating levels of control and uncertainty encountering with these. Through tangible experiments, the project discusses materiality and digitally controlled fabrications tools as direct expansions of the architect's digital drawing and workflow. The project sees this expansion as an opportunity to connect...

  10. Framing Fragmentation

    DEFF Research Database (Denmark)

    Bundgaard, Charlotte

    2009-01-01

    Contemporary industrialized architecture based on advanced information technology and highly technological production processes, implies a radically different approach to architecture than what we have experienced in the past. Works of architecture composed of prefabricated building components......, contain distinctive architectural traits, not only based on rational repetition, but also supporting composition and montage as dynamic concepts. Prefab architecture is an architecture of fragmentation, individualization and changeability, and this sets up new challenges for the architect. This paper...... tries to develop a strategy for the architect dealing with industrially based architecture; a strategy which exploits architectural potentials in industrial building, which recognizes the rules of mass production and which redefines the architect’s position among the agents of building. If recent...

  11. The determination of major and some minor constituents in lead zirconate-titanate compositions by x-ray fluorescence and atomic absorption spectrometry

    NARCIS (Netherlands)

    van Willigen, J.H.H.G.; Kruidhof, H.; Dahmen, E.A.M.F.

    1972-01-01

    An accurate X-ray fluorescence spectrometric method is described for the determination of lead, zirconium and titanium in lead zirconate-titanate ceramics. Careful matching of samples and standards by a borax fusion method resulted in a relative standard deviation of about 0.2% for the major

  12. Modern atomic physics

    CERN Document Server

    Natarajan, Vasant

    2015-01-01

    Much of our understanding of physics in the last 30-plus years has come from research on atoms, photons, and their interactions. Collecting information previously scattered throughout the literature, Modern Atomic Physics provides students with one unified guide to contemporary developments in the field. After reviewing metrology and preliminary material, the text explains core areas of atomic physics. Important topics discussed include the spontaneous emission of radiation, stimulated transitions and the properties of gas, the physics and applications of resonance fluorescence, coherence, cooling and trapping of charged and neutral particles, and atomic beam magnetic resonance experiments. Covering standards, a different way of looking at a photon, stimulated radiation, and frequency combs, the appendices avoid jargon and use historical notes and personal anecdotes to make the topics accessible to non-atomic physics students. Written by a leader in atomic and optical physics, this text gives a state-of-the...

  13. Fragmentation and Hadronization

    OpenAIRE

    Webber, B.R.

    1999-01-01

    Experimental data, theoretical ideas and models concerning jet fragmentation and the hadronization process are reviewed, concentrating on the following topics: factorization and small-x resummation of fragmentation functions, hadronization models, single-particle yields and spectra in Z decay, comparisons between quark and gluon jets, current and target fragmentation in deep inelastic scattering, heavy quark fragmentation, Bose-Einstein correlations and WW fragmentation.

  14. Fragmentation and Hadronization

    OpenAIRE

    Webber, B.R.

    2000-01-01

    Experimental data, theoretical ideas and models concerning jet fragmentation and the hadronization process are reviewed, concentrating on the following topics: factorization and small-x resummation of fragmentation functions, hadronization models, single-particle yields and spectra in Z decay, comparisons between quark and gluon jets, current and target fragmentation in deep inelastic scattering, heavy quark fragmentation, Bose-Einstein correlations and WW fragmentation.

  15. X-ray fluorescence holography

    CERN Document Server

    Hayashi, K; Takahashi, Y

    2003-01-01

    X-ray fluorescence holography (XFH) is a new structural analysis method of determining a 3D atomic arrangement around fluorescing atoms. We developed an XFH apparatus using advanced X-ray techniques and succeeded in obtaining high-quality hologram data. Furthermore, we introduced applications to the structural analysis of a thin film and the environment around dopants and, discussed the quantitative analysis of local lattice distortion. (author)

  16. Proposal for Testing and Validation of Vacuum Ultra-Violet Atomic Laser-Induced Fluorescence as a Method to Analyze Carbon Grid Erosion in Ion Thrusters

    Science.gov (United States)

    Stevens, Richard

    2003-01-01

    Previous investigation under award NAG3-25 10 sought to determine the best method of LIF to determine the carbon density in a thruster plume. Initial reports from other groups were ambiguous as to the number of carbon clusters that might be present in the plume of a thruster. Carbon clusters would certainly affect the ability to LIF; if they were the dominant species, then perhaps the LIF method should target clusters. The results of quadrupole mass spectroscopy on sputtered carbon determined that minimal numbers of clusters were sputtered from graphite under impact from keV Krypton. There were some investigations in the keV range by other groups that hinted at clusters, but at the time the proposal was presented to NASA, there was no data from low-energy sputtering available. Thus, the proposal sought to develop a method to characterize the population only of atoms sputtered from a graphite target in a test cell. Most of the ground work had been established by the previous two years of investigation. The proposal covering 2003 sought to develop an anti-Stokes Raman shifting cell to generate VUW light and test this cell on two different laser systems, ArF and YAG- pumped dye. The second goal was to measure the lowest detectable amounts of carbon atoms by 156.1 nm and 165.7 nm LIF. If equipment was functioning properly, it was expected that these goals would be met easily during the timeframe of the proposal, and that is the reason only modest funding was requested. The PI was only funded at half- time by Glenn during the summer months. All other work time was paid for by Whitworth College. The college also funded a student, Charles Shawley, who worked on the project during the spring.

  17. Determination of the electromagnetic dipole strength distribution in medium-heavy atomic nuclei by means of nuclear resonance fluorescence; Bestimmung der elektromagnetischen Dipolstaerkeverteilung in mittelschweren Atomkernen mittels Kernresonanzfluoreszenz

    Energy Technology Data Exchange (ETDEWEB)

    Massarczyk, Ralph Jens

    2011-01-17

    During the last hundred years several models were developed to describe the configuration of nuclei. These models have to make predictions, which should be comparable with experiments. As a standard type of experiment the nuclear resonance fluorescence was established. A nucleus is excited by irradiation with photons. By emitting one or more photons the nucleus decays back to the ground state. With this method it is possible to measure energy levels and to determine the strength of their excitation. A continuum of unresolved peaks gives additional strength. The existing setup at the linear electron accelerator ELBE of the Forschungszentrum Dresden-Rossendorf uses bremsstrahlung, produced as a secondary beam in a thin Niobium foil. During the years 2008/09 experiments on the nuclei of {sup 86}Kr and {sup 136}Ba took place there. In this work they will be analyzed. Photon flux and efficiency determination have been done as well as simulations on detector response and non-nuclear scattered background events. For this purpose the GEANT4 package was used. Finally the resulting cross sections were corrected for branching and feeding.

  18. Molecular energies from an incremental fragmentation method

    Science.gov (United States)

    Meitei, Oinam Romesh; Heßelmann, Andreas

    2016-02-01

    The systematic molecular fragmentation method by Collins and Deev [J. Chem. Phys. 125, 104104 (2006)] has been used to calculate total energies and relative conformational energies for a number of small and extended molecular systems. In contrast to the original approach by Collins, we have tested the accuracy of the fragmentation method by utilising an incremental scheme in which the energies at the lowest level of the fragmentation are calculated on an accurate quantum chemistry level while lower-cost methods are used to correct the low-level energies through a high-level fragmentation. In this work, the fragment energies at the lowest level of fragmentation were calculated using the random-phase approximation (RPA) and two recently developed extensions to the RPA while the incremental corrections at higher levels of the fragmentation were calculated using standard density functional theory (DFT) methods. The complete incremental fragmentation method has been shown to reproduce the supermolecule results with a very good accuracy, almost independent on the molecular type, size, or type of decomposition. The fragmentation method has also been used in conjunction with the DFT-SAPT (symmetry-adapted perturbation theory) method which enables a breakdown of the total nonbonding energy contributions into individual interaction energy terms. Finally, the potential problems of the method connected with the use of capping hydrogen atoms are analysed and two possible solutions are supplied.

  19. SCEDS: protein fragments for molecular replacement in Phaser

    Energy Technology Data Exchange (ETDEWEB)

    McCoy, Airlie J., E-mail: ajm201@cam.ac.uk [University of Cambridge, Hills Road, Cambridge CB2 0XY (United Kingdom); Nicholls, Robert A. [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH (United Kingdom); Schneider, Thomas R. [Hamburg Unit c/o DESY, Notkestrasse 85, 22603 Hamburg (Germany); University of Cambridge, Hills Road, Cambridge CB2 0XY (United Kingdom)

    2013-11-01

    Protein fragments suitable for use in molecular replacement can be generated by normal-mode perturbation, analysis of the difference distance matrix of the original versus normal-mode perturbed structures, and SCEDS, a score that measures the sphericity, continuity, equality and density of the resulting fragments. A method is described for generating protein fragments suitable for use as molecular-replacement (MR) template models. The template model for a protein suspected to undergo a conformational change is perturbed along combinations of low-frequency normal modes of the elastic network model. The unperturbed structure is then compared with each perturbed structure in turn and the structurally invariant regions are identified by analysing the difference distance matrix. These fragments are scored with SCEDS, which is a combined measure of the sphericity of the fragments, the continuity of the fragments with respect to the polypeptide chain, the equality in number of atoms in the fragments and the density of C{sup α} atoms in the triaxial ellipsoid of the fragment extents. The fragment divisions with the highest SCEDS are then used as separate template models for MR. Test cases show that where the protein contains fragments that undergo a change in juxtaposition between template model and target, SCEDS can identify fragments that lead to a lower R factor after ten cycles of all-atom refinement with REFMAC5 than the original template structure. The method has been implemented in the software Phaser.

  20. Detection of vapor phase mercury species by laser fluorescence methods

    Science.gov (United States)

    Tong, Xiaomei

    Several mercury species emissions have been identified in off-gases from industrial processes. At present, there is no commercial continuous emission monitoring (CEM) technique or instrumentation to reliably monitor volatile mercury species emissions from industrial stacks. Conventional measurement methods, such as cold vapor trap based techniques for elemental mercury, have difficulty in achieving both high sensitivity and the fast time resolution required for real-time monitoring. This doctoral research work gives a systematic study of potential methods for real-time trace detection of volatile elemental mercury and mercury compounds in industrial stack gases. It is based on laser-induced fluorescence techniques; photofragment fluorescence spectroscopy for detection of volatile mercury compounds, and resonance fluorescence for detection of elemental mercury. The capabilities and limitations of these detection techniques are investigated in this dissertation. Detection of mercury compounds is a challenge since they are non-fluorescent. With photofragment fluorescence spectroscopy, target compound concentrations are related to the fluorescence intensity from an excited fragment. In this doctoral research work, low concentrations of mercuric bromide vapor in an atmospheric pressure flow cell are irradiated by a focused laser beam at 222nm. Photofragment fluorescence is monitored at 253.7nm. Two detection schemes, Charge Coupled Device (CCD) and photomultiplier tube (PMT), are applied for the measurement of photofragment fluorescence. The performances of these two systems are compared in the dissertation. A supersonic jet is combined with resonance fluorescence for detection of elemental mercury vapor. With test gas expanded into a vacuum, fluorescence quenching and spectral broadening are reduced. In the experiment, the gas jet is crossed with a laser beam at 253.7nm to excite atomic fluorescence, which is distinguished from the elastic background by time gating

  1. Chemical characterization of archaeological ceramics fragments by X-ray ({mu}-XRF) micro fluorescence; Caracterizacao quimica de fragmentos ceramicos arqueologicos por microfluorescencia de raios X ({mu}-XRF)

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Richard Maximiliano da Cunha e; Nascimento Filho, Virgilio Franco do [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil); Appoloni, Carlos Roberto [Universidade Estadual de Londrina, PR (Brazil); Perez, Carlos Alberto [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil)

    2002-07-01

    The concentrations of the inorganic chemical elements presents in archaeological ceramic samples and clay samples allows the study about the clay sources determination used in the ceramic production. The analyzed samples are fragments of Brazilian indigenous ceramic, found in the area of the city of Londrina, North of Parana, and they belong to the archaeological collection of the 'Padre Carlos Weiss' Historical Museum, of the State University of Londrina. The determination of the chemical elements in these fragments was performed by energy dispersive X-ray microfluorescence ({mu}-XRF), for being not destructive and multielementar. The analytic technique allowed the identification of the K, Ca, Ti, Mn, Fe minority elements, and the Cr, Ni, Cu, Zn and Rb trace elements. The cluster analysis for the method of the medium grouping was used, and it was obtained two different groups, taking to conclude that indigenous Tupiguaranis used two clay sources in the making of its ceramic. (author)

  2. Fractionation and redox speciation of antimony in agricultural soils by hydride generation--atomic fluorescence spectrometry and stability of Sb(III) and Sb(V) during extraction with different extractant solutions.

    Science.gov (United States)

    Fuentes, Edwar; Pinochet, Hugo; Potin-Gautier, Martine; De Graegori, Ida

    2004-01-01

    This stability of Sb(III) and Sb(V) species was studied during single extraction from soils by water. EDTA, diluted H2SO4 and H3PO4, and oxalic acid/oxalate solutions, with and without ascorbic acid, were used as stabilizing reagent of both Sb species. Antimony redox speciation in soil extracts was performed by selective hydride generation-atomic fluorescence spectrometry. Simulated extraction procedures (without soil) showed that, except in oxalate medium, Sb(III) was oxidized to Sb(V), and this reaction was avoided with ascorbic acid. Recovery studies from a spiked agricultural soil showed that no oxidation but sorption of Sb(III) occurred during the extraction process in water and H2SO4 medium, and quantitative oxidation in EDTA and oxalate medium. With ascorbic acid, this oxidation was totally avoided in EDTA and partially avoided in oxalate solution. A new sequential extraction procedure was proposed and applied to the fractionation and redox speciation of antimony in agricultural soils, using EDTA + ascorbic acid, pH 7 (available under complexing and moderately reducible conditions); oxalic acid/oxalate + ascorbic acid (extractable in reducible conditions) and HNO3 + HCl + HF (residual fraction). The proposed extraction scheme can provide information about the availability and mobility of antimony redox species in agricultural soils.

  3. Design Tools for FRIB Fragment Separators

    Science.gov (United States)

    Bandura, Laura

    2009-10-01

    A key component of the Facility for Rare Isotope Beams, FRIB will be the in-flight fragment separator used to select and purify the isotope of interest for experiments. In order to simulate this process, we have developed a hybrid map-Monte Carlo code based on the ion optics code COSY INFINITY that accurately models fragment production and atomic processes. The code COSY INFINTIY uses powerful differential algebraic methods for computing the dynamics of the beam in the fragment separator. Ion production and atomic processes have been added to COSY to calculate beam-material interactions. The code tracks the fragmentation and fission of the beam in target and absorber material while computing energy loss and energy and angular straggling as well as charge state evolution of the beam by implementing auxiliary codes such as ATIMA and GLOBAL. EPAX has been utilized to return the cross sections of fragmentation products. The hybrid map-Monte Carlo code extensions added to COSY provide an integrated beam dynamics-nuclear processes design optimization and simulation framework that is efficient and accurate. The code may be used to optimize any fragment separator system for the selection of any rare isotope.

  4. Analysis of fragmentations of coumarins in mass spectrometry using ...

    African Journals Online (AJOL)

    A good correlation was found between electronic charges of atoms and fragmentation processes. In the present study, another series of coumarins with nitrogenated moieties is used to verify the reliability of this method. KEY WORDS: 4,7-Disubstituted coumarins, Nitrogenated moiety, AM1, Electronic charge, Fragmentation, ...

  5. An apertureless near-field microscope for fluorescence imaging

    OpenAIRE

    Yang, T. J.; Lessard, Guillaume A.; Quake, Stephen R.

    2000-01-01

    We describe an apertureless near field microscope for imaging fluorescent samples. Optical contrast is generated by exploiting fluorescent quenching near a metallized atomic force microscope tip. This microscope has been used to image fluorescent latex beads with subdiffraction limit resolution. The use of fluorescence allows us to prove that the contrast mechanism is indeed spectroscopic in origin.

  6. Fluorescence spectroscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2016-01-01

    Fluorescence spectroscopy is a powerful experimental tool used by scientists from many disciplines. During the last decades there have been important developments on distinct fluorescence methods, particularly those related to the study of biological phenomena. This chapter discusses...... the foundations of the fluorescence phenomenon, introduces some general methodologies and provides selected examples on applications focused to disentangle structural and dynamical aspects of biological processes....

  7. A direct interaction between the sigma-1 receptor and the hERG voltage-gated K+ channel revealed by atomic force microscopy and homogeneous time-resolved fluorescence (HTRF®).

    Science.gov (United States)

    Balasuriya, Dilshan; D'Sa, Lauren; Talker, Ronel; Dupuis, Elodie; Maurin, Fabrice; Martin, Patrick; Borgese, Franck; Soriani, Olivier; Edwardson, J Michael

    2014-11-14

    The sigma-1 receptor is an endoplasmic reticulum chaperone protein, widely expressed in central and peripheral tissues, which can translocate to the plasma membrane and modulate the function of various ion channels. The human ether-à-go-go-related gene encodes hERG, a cardiac voltage-gated K(+) channel that is abnormally expressed in many human cancers and is known to interact functionally with the sigma-1 receptor. Our aim was to investigate the nature of the interaction between the sigma-1 receptor and hERG. We show that the two proteins can be co-isolated from a detergent extract of stably transfected HEK-293 cells, consistent with a direct interaction between them. Atomic force microscopy imaging of the isolated protein confirmed the direct binding of the sigma-1 receptor to hERG monomers, dimers, and tetramers. hERG dimers and tetramers became both singly and doubly decorated by sigma-1 receptors; however, hERG monomers were only singly decorated. The distribution of angles between pairs of sigma-1 receptors bound to hERG tetramers had two peaks, at ∼90 and ∼180° in a ratio of ∼2:1, indicating that the sigma-1 receptor interacts with hERG with 4-fold symmetry. Homogeneous time-resolved fluorescence (HTRF®) allowed the detection of the interaction between the sigma-1 receptor and hERG within the plane of the plasma membrane. This interaction was resistant to sigma ligands, but was decreased in response to cholesterol depletion of the membrane. We suggest that the sigma-1 receptor may bind to hERG in the endoplasmic reticulum, aiding its assembly and trafficking to the plasma membrane. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. Ligament Mediated Fragmentation of Viscoelastic Liquids

    Science.gov (United States)

    Keshavarz, Bavand; Houze, Eric C.; Moore, John R.; Koerner, Michael R.; McKinley, Gareth H.

    2016-10-01

    The breakup and atomization of complex fluids can be markedly different than the analogous processes in a simple Newtonian fluid. Atomization of paint, combustion of fuels containing antimisting agents, as well as physiological processes such as sneezing are common examples in which the atomized liquid contains synthetic or biological macromolecules that result in viscoelastic fluid characteristics. Here, we investigate the ligament-mediated fragmentation dynamics of viscoelastic fluids in three different canonical flows. The size distributions measured in each viscoelastic fragmentation process show a systematic broadening from the Newtonian solvent. In each case, the droplet sizes are well described by Gamma distributions which correspond to a fragmentation-coalescence scenario. We use a prototypical axial step strain experiment together with high-speed video imaging to show that this broadening results from the pronounced change in the corrugated shape of viscoelastic ligaments as they separate from the liquid core. These corrugations saturate in amplitude and the measured distributions for viscoelastic liquids in each process are given by a universal probability density function, corresponding to a Gamma distribution with nmin=4 . The breadth of this size distribution for viscoelastic filaments is shown to be constrained by a geometrical limit which can not be exceeded in ligament-mediated fragmentation phenomena.

  9. Inhibition of Chk1 by CEP-3891 accelerates mitotic nuclear fragmentation in response to ionizing Radiation

    DEFF Research Database (Denmark)

    Syljuåsen, Randi G; Sørensen, Claus Storgaard; Nylandsted, Jesper

    2004-01-01

    %) of cells showed fragmented nuclei at 24 hours after IR (6 Gy). The formation of nuclear fragmentation in IR-treated human cancer cells was directly visualized by time-lapse video microscopy of U2-OS cells expressing a green fluorescent protein-tagged histone H2B protein. Nuclear fragmentation occurred...

  10. Atomic polarizabilities

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)

    2015-01-22

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.

  11. Atomic Physics

    CERN Document Server

    Foot, Christopher J

    2007-01-01

    This text will thoroughly update the existing literature on atomic physics. Intended to accompany an advanced undergraduate course in atomic physics, the book will lead the students up to the latest advances and the applications to Bose-Einstein Condensation of atoms, matter-wave inter-ferometry and quantum computing with trapped ions. The elementary atomic physics covered in the early chapters should be accessible to undergraduates when they are first introduced to the subject. To complement. the usual quantum mechanical treatment of atomic structure the book strongly emphasizes the experimen

  12. Ultracold atoms on atom chips

    DEFF Research Database (Denmark)

    Krüger, Peter; Hofferberth, S.; Haller, E.

    2005-01-01

    Miniaturized potentials near the surface of atom chips can be used as flexible and versatile tools for the manipulation of ultracold atoms on a microscale. The full scope of possibilities is only accessible if atom-surface distances can be reduced to microns. We discuss experiments in this regime...

  13. Liquid chromatography-hydride generation-atomic fluorescence spectrometry determination of arsenic species in dog plasma and its application to a pharmacokinetic study after oral administration of Realgar and Niu Huang Jie Du Pian.

    Science.gov (United States)

    Zhang, Yunjing; Qiang, Shuping; Sun, Jing; Song, Min; Hang, Taijun

    2013-02-15

    A high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) method was developed for the simultaneous determination of four arsenic species (As(III), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and arsenate As(V)) in dog plasma. Good separation of the four arsenic species was achieved within 15min on an anion-exchange column with isocratic elution using 15mmol/L KH(2)PO(4) (pH 5.9) as eluent at a flow rate of 1.0mL/min. The assay was linear over the range of 1.25-200, 1.56-200, 1.34-172, and 2.50-200ng/mL with the detection limits of 0.80, 1.00, 0.86 and 2.00ng/mL for As(III), DMA, MMA and As(V), respectively. The method was validated for selectivity, precision, accuracy and recovery and then applied to a comparative pharmacokinetic study of the arsenic species in beagle dogs after a single oral administration of Realgar (24.32mg/kg, equivalent to 11.31mgAs/kg) alone or Niu Huang Jie Du Pian (a patent traditional Chinese medicine (TCM), 380mg/kg, equivalent to 28.45mgAs/kg), respectively. DMA was found to be the predominant species in the dog plasma after dosing, with As(V) appeared as the quickly eliminating one. No traces of MMA and As(III) were detected at any sampling time points. The main pharmacokinetic parameters found for DMA p.o. administration of Realgar and Niu Huang Jie Du Pian were as follows: C(max) (14.7±4.2) and (57.0±32.0)ng/mL, T(max) (2.4±0.5) and (2.5±0.5)h, AUC(0-36) (151.1±12.9) and (635.9±418.2)ngh/mL, AUC(0-∞) (206.0±44.5) and (687.2±425.1)ngh/mL, t(1/2) (16.2±7.9) and (9.4±2.2)h, respectively. The influence of compounding in Niu Huang Jie Du Pian on the pharmacokinetics of arsenics was shown with increased transformation of DMA and its faster elimination rate. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Fragmentation in Carbon Therapy Beams

    CERN Document Server

    Charara, Y M

    2010-01-01

    The state of the art Monte Carlo code HETC-HEDS was used to simulate spallation products, secondary neutron, and secondary proton production in A-150 Tissue Equivalent Plastic phantoms to investigate fragmentation of carbon therapy beams. For a 356 MeV/Nucleon carbon ion beam, production of charged particles heavier than protons was 0.24 spallation products per incident carbon ion with atomic numbers ranging from 1 through 5 (hydrogen to boron). In addition, there were 4.73 neutrons and 2.95 protons produced per incident carbon ion. Furthermore, as the incident energy increases, the neutron production rate increases at a rate of 20% per 10 MeV/nucleon. Secondary protons were created at a rate between 2.62-2.87 per carbon ion, while spallation products were created at a rate between 0.20-0.24 per carbon ion.

  15. Fragmentation trees reloaded.

    Science.gov (United States)

    Böcker, Sebastian; Dührkop, Kai

    2016-01-01

    Untargeted metabolomics commonly uses liquid chromatography mass spectrometry to measure abundances of metabolites; subsequent tandem mass spectrometry is used to derive information about individual compounds. One of the bottlenecks in this experimental setup is the interpretation of fragmentation spectra to accurately and efficiently identify compounds. Fragmentation trees have become a powerful tool for the interpretation of tandem mass spectrometry data of small molecules. These trees are determined from the data using combinatorial optimization, and aim at explaining the experimental data via fragmentation cascades. Fragmentation tree computation does not require spectral or structural databases. To obtain biochemically meaningful trees, one needs an elaborate optimization function (scoring). We present a new scoring for computing fragmentation trees, transforming the combinatorial optimization into a Maximum A Posteriori estimator. We demonstrate the superiority of the new scoring for two tasks: both for the de novo identification of molecular formulas of unknown compounds, and for searching a database for structurally similar compounds, our method SIRIUS 3, performs significantly better than the previous version of our method, as well as other methods for this task. SIRIUS 3 can be a part of an untargeted metabolomics workflow, allowing researchers to investigate unknowns using automated computational methods.Graphical abstractWe present a new scoring for computing fragmentation trees from tandem mass spectrometry data based on Bayesian statistics. The best scoring fragmentation tree most likely explains the molecular formula of the measured parent ion.

  16. Fragmentation of monoclonal antibodies

    Science.gov (United States)

    Vlasak, Josef

    2011-01-01

    Fragmentation is a degradation pathway ubiquitously observed in proteins despite the remarkable stability of peptide bond; proteins differ only by how much and where cleavage occurs. The goal of this review is to summarize reports regarding the non-enzymatic fragmentation of the peptide backbone of monoclonal antibodies (mAbs). The sites in the polypeptide chain susceptible to fragmentation are determined by a multitude of factors. Insights are provided on the intimate chemical mechanisms that can make some bonds prone to cleavage due to the presence of specific side-chains. In addition to primary structure, the secondary, tertiary and quaternary structures have a significant impact in modulating the distribution of cleavage sites by altering local flexibility, accessibility to solvent or bringing in close proximity side chains that are remote in sequence. This review focuses on cleavage sites observed in the constant regions of mAbs, with special emphasis on hinge fragmentation. The mechanisms responsible for backbone cleavage are strongly dependent on pH and can be catalyzed by metals or radicals. The distribution of cleavage sites are different under acidic compared to basic conditions, with fragmentation rates exhibiting a minimum in the pH range 5–6; therefore, the overall fragmentation pattern observed for a mAb is a complex result of structural and solvent conditions. A critical review of the techniques used to monitor fragmentation is also presented; usually a compromise has to be made between a highly sensitive method with good fragment separation and the capability to identify the cleavage site. The effect of fragmentation on the function of a mAb must be evaluated on a case-by-case basis depending on whether cleavage sites are observed in the variable or constant regions, and on the mechanism of action of the molecule. PMID:21487244

  17. DNA sequencing using fluorescence background electroblotting membrane

    Science.gov (United States)

    Caldwell, K.D.; Chu, T.J.; Pitt, W.G.

    1992-05-12

    A method for the multiplex sequencing on DNA is disclosed which comprises the electroblotting or specific base terminated DNA fragments, which have been resolved by gel electrophoresis, onto the surface of a neutral non-aromatic polymeric microporous membrane exhibiting low background fluorescence which has been surface modified to contain amino groups. Polypropylene membranes are preferably and the introduction of amino groups is accomplished by subjecting the membrane to radio or microwave frequency plasma discharge in the presence of an aminating agent, preferably ammonia. The membrane, containing physically adsorbed DNA fragments on its surface after the electroblotting, is then treated with crosslinking means such as UV radiation or a glutaraldehyde spray to chemically bind the DNA fragments to the membrane through amino groups contained on the surface. The DNA fragments chemically bound to the membrane are subjected to hybridization probing with a tagged probe specific to the sequence of the DNA fragments. The tagging may be by either fluorophores or radioisotopes. The tagged probes hybridized to the target DNA fragments are detected and read by laser induced fluorescence detection or autoradiograms. The use of aminated low fluorescent background membranes allows the use of fluorescent detection and reading even when the available amount of DNA to be sequenced is small. The DNA bound to the membranes may be reprobed numerous times. No Drawings

  18. A probabilistic fragment-based protein structure prediction algorithm.

    Science.gov (United States)

    Simoncini, David; Berenger, Francois; Shrestha, Rojan; Zhang, Kam Y J

    2012-01-01

    Conformational sampling is one of the bottlenecks in fragment-based protein structure prediction approaches. They generally start with a coarse-grained optimization where mainchain atoms and centroids of side chains are considered, followed by a fine-grained optimization with an all-atom representation of proteins. It is during this coarse-grained phase that fragment-based methods sample intensely the conformational space. If the native-like region is sampled more, the accuracy of the final all-atom predictions may be improved accordingly. In this work we present EdaFold, a new method for fragment-based protein structure prediction based on an Estimation of Distribution Algorithm. Fragment-based approaches build protein models by assembling short fragments from known protein structures. Whereas the probability mass functions over the fragment libraries are uniform in the usual case, we propose an algorithm that learns from previously generated decoys and steers the search toward native-like regions. A comparison with Rosetta AbInitio protocol shows that EdaFold is able to generate models with lower energies and to enhance the percentage of near-native coarse-grained decoys on a benchmark of [Formula: see text] proteins. The best coarse-grained models produced by both methods were refined into all-atom models and used in molecular replacement. All atom decoys produced out of EdaFold's decoy set reach high enough accuracy to solve the crystallographic phase problem by molecular replacement for some test proteins. EdaFold showed a higher success rate in molecular replacement when compared to Rosetta. Our study suggests that improving low resolution coarse-grained decoys allows computational methods to avoid subsequent sampling issues during all-atom refinement and to produce better all-atom models. EdaFold can be downloaded from http://www.riken.jp/zhangiru/software.html [corrected].

  19. Atomic physics

    CERN Document Server

    Born, Max

    1969-01-01

    The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.

  20. Early Atomism

    Indian Academy of Sciences (India)

    http://www.ias.ac.in/article/fulltext/reso/015/10/0905-0925. Keywords. Atomic theory; Avogadro's hypothesis; atomic weights; periodic table; valence; molecular weights; molecular formula; isomerism. Author Affiliations. S Ramasesha1. Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, ...

  1. Embedded Fragments Registry (EFR)

    Data.gov (United States)

    Department of Veterans Affairs — In 2009, the Department of Defense estimated that approximately 40,000 service members who served in OEF/OIF may have embedded fragment wounds as the result of small...

  2. Fragmentation Main Model

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The fragmentation model combines patch size and patch continuity with diversity of vegetation types per patch and rarity of vegetation types per patch. A patch was...

  3. DNA fragmentation in spermatozoa

    DEFF Research Database (Denmark)

    Rex, A S; Aagaard, J.; Fedder, J

    2017-01-01

    Sperm DNA Fragmentation has been extensively studied for more than a decade. In the 1940s the uniqueness of the spermatozoa protein complex which stabilizes the DNA was discovered. In the fifties and sixties, the association between unstable chromatin structure and subfertility was investigated....... In the seventies, the impact of induced DNA damage was investigated. In the 1980s the concept of sperm DNA fragmentation as related to infertility was introduced as well as the first DNA fragmentation test: the Sperm Chromatin Structure Assay (SCSA). The terminal deoxynucleotidyl transferase nick end labelling...... (TUNEL) test followed by others was introduced in the nineties. The association between DNA fragmentation in spermatozoa and pregnancy loss has been extensively investigated spurring the need for a therapeutic tool for these patients. This gave rise to an increased interest in the aetiology of DNA damage...

  4. Fragmented Work Stories

    DEFF Research Database (Denmark)

    Humle, Didde Maria; Reff Pedersen, Anne

    2015-01-01

    stories. We argue that meaning by story making is not always created by coherence and causality; meaning is created by different types of fragmentation: discontinuities, tensions and editing. The objective of this article is to develop and advance antenarrative practice analysis of work stories......Following a strand of narrative studies pointing to the living conditions of storytelling and the micro-level implications of working within fragmented narrative perspectives, this article contributes to narrative research on work stories by focusing on how meaning is created from fragmented...... by exploring how different types of fragmentation create meanings. This is done by studying the work stories of job and personnel consultants and by drawing on the results of a narrative, ethnographic study of a consultancy. The analysis demonstrates how work stories are social practices negotiated, retold...

  5. Application of total reflection X-ray fluorescence spectrometry for ...

    Indian Academy of Sciences (India)

    in rainwater are, inductively coupled plasma-mass spectrometry (ICPMS), inductively coupled plasma-atomic emission spectrometry (ICP-AES), atomic absorption spectrom- etry (AAS), X-ray fluorescence (XRF), total reflection X-ray fluorescence (TXRF), neu- tron activation analysis (NAA), electroanalytical techniques, etc.

  6. Crystallographic fragment screening.

    Science.gov (United States)

    Badger, John

    2012-01-01

    Crystallographic fragment screening is a technique for initiating drug discovery in which protein crystals are soaked or grown with high concentrations of small molecule compounds (typically MW 110-250 Da) chosen to represent fragments of potential drugs. Specific binding of these compounds to the protein is subsequently visualized in electron density maps obtained from analysis of X-ray diffraction data collected from these crystals. Theoretical and practical experience indicate that a suitably diverse library of fragment compounds containing only a few hundred compounds may be sufficient to provide a comprehensive screen of the protein target. By soaking crystals in mixtures of 3-10 compounds a fragment screen may be completed within ∼100 diffraction data sets. This data collection requirement may be met given reproducible well-diffracting protein crystals and robotic sample handling equipment at a high flux X-ray source. The leading practical issue for most crystallography laboratories that wish to launch a fragment screening project is the design and/or procurement of an appropriate fragment library. Although several off-the-shelf fragment libraries are available from chemical suppliers, the numbers, sizes, and solubility of the compounds in relatively few of these libraries are well-match to the specific needs of the crystallographic screening experiment. Informed consideration of the properties of compounds in the screening library, possibly augmented by additional filtering of available compounds with appropriate search tools, is required to design a successful experiment. The analysis of results from crystallographic fragment screening involves highly repetitive application of routine image data processing and structure refinement calculations from many very similar crystals. Efficient handling of the data applies a high-throughput structure determination methodology that conveniently packages the structure solution calculations into a single process that

  7. Fragment Impact Toolkit (FIT)

    Energy Technology Data Exchange (ETDEWEB)

    Shevitz, Daniel Wolf [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Key, Brian P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Garcia, Daniel B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-05

    The Fragment Impact Toolkit (FIT) is a software package used for probabilistic consequence evaluation of fragmenting sources. The typical use case for FIT is to simulate an exploding shell and evaluate the consequence on nearby objects. FIT is written in the programming language Python and is designed as a collection of interacting software modules. Each module has a function that interacts with the other modules to produce desired results.

  8. Microwave Spectroscopy of Cold Rubidium Atoms

    OpenAIRE

    Entin, V. M.; Ryabtsev, I. I.

    2004-01-01

    The effect of microwave radiation on the resonance fluorescence of a cloud of cold $^{85}Rb$ atoms in a magnetooptical trap is studied. The radiation frequency was tuned near the hyperfine splitting frequency of rubidium atoms in the 5S ground state. The microwave field induced magnetic dipole transitions between the magnetic sublevels of the 5S(F=2) and 5S(F=3) states, resulting in a change in the fluorescence signal. The resonance fluorescence spectra were recorded by tuning the microwave r...

  9. Ternary-fragmentation-driving potential energies of 252Cf

    Science.gov (United States)

    Karthikraj, C.; Ren, Zhongzhou

    2017-12-01

    Within the framework of a simple macroscopic model, the ternary-fragmentation-driving potential energies of 252Cf are studied. In this work, all possible ternary-fragment combinations of 252Cf are generated by the use of atomic mass evaluation-2016 (AME2016) data and these combinations are minimized by using a two-dimensional minimization approach. This minimization process can be done in two ways: (i) with respect to proton numbers (Z1, Z2, Z3) and (ii) with respect to neutron numbers (N1, N2, N3) of the ternary fragments. In this paper, the driving potential energies for the ternary breakup of 252Cf are presented for both the spherical and deformed as well as the proton-minimized and neutron-minimized ternary fragments. From the proton-minimized spherical ternary fragments, we have obtained different possible ternary configurations with a minimum driving potential, in particular, the experimental expectation of Sn + Ni + Ca ternary fragmentation. However, the neutron-minimized ternary fragments exhibit a driving potential minimum in the true-ternary-fission (TTF) region as well. Further, the Q -value energy systematics of the neutron-minimized ternary fragments show larger values for the TTF fragments. From this, we have concluded that the TTF region fragments with the least driving potential and high Q values have a strong possibility in the ternary fragmentation of 252Cf. Further, the role of ground-state deformations (β2, β3, β4, and β6) in the ternary breakup of 252Cf is also studied. The deformed ternary fragmentation, which involves Z3=12 -19 fragments, possesses the driving potential minimum due to the larger oblate deformations. We also found that the ground-state deformations, particularly β2, strongly influence the driving potential energies and play a major role in determining the most probable fragment combinations in the ternary breakup of 252Cf.

  10. Mass Spectral Fragmentation of VX

    National Research Council Canada - National Science Library

    Rohrbaugh, Dennis K

    2008-01-01

    The objective of this study was to provide structural identification of VX fragment ions formed during mass spectrometric analysis, elucidation of fragmentation pathways, and a compilation of tandem...

  11. HDX reveals unique fragment ligands for the vitamin D receptor.

    Science.gov (United States)

    Carson, Matthew W; Zhang, Jun; Chalmers, Michael J; Bocchinfuso, Wayne P; Holifield, Karol D; Masquelin, Thierry; Stites, Ryan E; Stayrook, Keith R; Griffin, Patrick R; Dodge, Jeffery A

    2014-08-01

    Modulation of the vitamin D receptor (VDR) with a ligand has the potential to be useful for the oral treatment of osteoporosis. One component of our lead generation strategy to identify synthetic ligands for VDR included a fragment based drug design approach. Screening of ligands in a VDR fluorescence polarization assay and a RXR/VDR conformation sensing assay resulted in the identification of multiple fragment hits (lean >0.30). These fragment scaffolds were subsequently evaluated for interaction with the VDR ligand binding domain using hydrogen-deuterium exchange (HDX) mass spectrometry. Significant protection of H/D exchange was observed for some fragments in helixes 3, 7, and 8 of the ligand binding domain, regions which are similar to those seen for the natural hormone VD3. The fragments appear to mimic the A-ring of VD3 thereby providing viable starting points for synthetic expansion. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Fragmentation processes of OCS in collision with highly charged ions

    Science.gov (United States)

    Matsumoto, J.; Tezuka, T.; Fukutome, A.; Karimi, R.; Wales, B.; Sanderson, J. H.; Shiromaru, H.

    2014-04-01

    Fragmentation of (OCS)3+ and (OCS)4+ produced by 120 keV Ar8+ collision was studied by using a position-sensitive time-of-flight (PS-TOF) method. We identified stepwise processes involving CO2+ and CS2+ metastable species as well as the concerted process (simultaneous breakup of the two bonds). For the (OCS)4+ events, the stepwise processes were found for fragmentation channels containing a doubly-charged terminal atom.

  13. Isotopic Scaling and the Symmetry Energy in Spectator Fragmentation

    OpenAIRE

    INDRA, The; collaborations, ALADIN; :; Fèvre, A. Le; Auger, G.; Begemann-Blaich, M.L.; Bellaize, N.; Bittiger, R.; Bocage, F.; Borderie, B.; R. Bougault(LPCC); Bouriquet, B.; Charvet, J. L.; Chbihi, A.; Dayras, R.

    2004-01-01

    Isotopic effects in the fragmentation of excited target residues following collisions of $^{12}$C on $^{112,124}$Sn at incident energies of 300 and 600 MeV per nucleon were studied with the INDRA 4$\\pi$ detector. The measured yield ratios for light particles and fragments with atomic number $Z \\leq$ 5 obey the exponential law of isotopic scaling. The deduced scaling parameters decrease strongly with increasing centrality to values smaller than 50% of those obtained for the peripheral event gr...

  14. Fragments of Time

    DEFF Research Database (Denmark)

    Christiansen, Steen Ledet

    Time travel films necessarily fragment linear narratives, as scenes are revisited with differences from the first time we saw it. Popular films such as Back to the Future mine comedy from these visitations, but there are many different approaches. One extreme is Chris Marker's La Jetée - a film...... made almost completely of still images, recounting the end of the world. These stills can be viewed as fragments that have survived the end of the world and now provide the only access to the events that occured. Shane Carruth's Primer has a different approach to time travel, the narrative diegesis...

  15. The Serendipity of Fragmentation

    DEFF Research Database (Denmark)

    Leixnering, Stephan; Meyer, Renate E.

    , it was the central government’s task to coordinate, steer and control the newly emerged decentralized organizations. This raises questions about the overall design of the public sector at present. Our paper engages with the prevalent public governance phenomenon of fragmentation from a design perspective in order...... form of organizing between networks and formal organization: lacking a single center and featuring multiplex and multifaceted relations within the politico-administrative apparatus and between government and PSOs, high fragmentation, local and robust action, but latent structures of significant formal...

  16. Laser stabilisation for velocity-selective atomic absorption

    NARCIS (Netherlands)

    Meijer, H.A.J.; Meulen, H.P. van der; Ditewig, F.; Wisman, C.J.; Morgenstern, R.

    1987-01-01

    A relatively simple method is described for stabilising a dye laser at a frequency ν = ν0 + νc in the vicinity of an atomic resonance frequency ν0. The Doppler effect is exploited by looking for atomic fluorescence when a laser beam is crossed with an atomic beam at certain angles αi. Absolute

  17. Protein subcellular localization assays using split fluorescent proteins

    Science.gov (United States)

    Waldo, Geoffrey S [Santa Fe, NM; Cabantous, Stephanie [Los Alamos, NM

    2009-09-08

    The invention provides protein subcellular localization assays using split fluorescent protein systems. The assays are conducted in living cells, do not require fixation and washing steps inherent in existing immunostaining and related techniques, and permit rapid, non-invasive, direct visualization of protein localization in living cells. The split fluorescent protein systems used in the practice of the invention generally comprise two or more self-complementing fragments of a fluorescent protein, such as GFP, wherein one or more of the fragments correspond to one or more beta-strand microdomains and are used to "tag" proteins of interest, and a complementary "assay" fragment of the fluorescent protein. Either or both of the fragments may be functionalized with a subcellular targeting sequence enabling it to be expressed in or directed to a particular subcellular compartment (i.e., the nucleus).

  18. Molecular markers. Amplified fragment length polymorphism

    Directory of Open Access Journals (Sweden)

    Pržulj Novo

    2005-01-01

    Full Text Available Amplified Fragment Length Polymorphism molecular markers (AFLPs has been developed combining procedures of RFLPs and RAPDs molekular markers, i.e. the first step is restriction digestion of the genomic DNA that is followed by selective amplification of the restricted fragments. The advantage of the AFLP technique is that it allows rapid generation of a large number of reproducible markers. The reproducibility of AFLPs markers is assured by the use of restriction site-specific adapters and adapter-specific primers for PCR reaction. Only fragments containing the restriction site sequence plus the additional nucleotides will be amplified and the more selected nucleotides added on the primer sequence the fewer the number of fragments amplified by PCR. The amplified products are normally separated on a sequencing gel and visualized after exposure to X-ray film or by using fluorescent labeled primers. AFLP shave proven to be extremely proficient in revealing diversity at below the species level. A disadvantage of AFLP technique is that AFLPs are essentially a dominant marker system and not able to identify heterozygotes.

  19. Non-destructive state measurement of individual neutral atoms

    Science.gov (United States)

    Gibbons, Michael; Shih, Chung-Yu; Hamley, Chris; Chapman, Michael

    2011-05-01

    Non-destructive state detection of individual neutral atoms is essential for scalable neutral atom quantum information processing. We have demonstrated non-destructive fluorescent state detection of individual neutral atom qubits trapped in an optical lattice. The hyperfine state of the atom is measured with 95% accuracy and the atom loss rate of 1%. State detection is performed on individual atoms over 100 times before being lost from the trap, representing a significant increase in the data collection rates. Using this technique, we have observed microwave Rabi oscillations with measurements done on one-and-the-same atom.

  20. Stone fragmentation by ultrasound

    Indian Academy of Sciences (India)

    Some delicate nerves and fibres in the surrounding areas of the stones present in the kidney are also damaged by high ultrasonic intensity used in such systems. In the present work, enhancement of the kidney stone fragmentation by using ultrasound is studied. The cavitation bubbles are found to implode faster, with more ...

  1. Fragments of the Past

    Directory of Open Access Journals (Sweden)

    Peter Szende

    2016-10-01

    Full Text Available With travel being made more accessible throughout the decades, the hospitality industry constantly evolved their practices as society and technology progressed. Hotels looked for news ways up service their customers, which led to the invention of the Servidor in 1918. Once revolutionary innovations have gone extinct, merely becoming fragments of the past.

  2. Wildlife habitat fragmentation.

    Science.gov (United States)

    John. Lehmkuhl

    2005-01-01

    A primary issue in forest wildlife management is habitat fragmentation and its effects on viability, which is the "bottom line" for plant and animal species of conservation concern. Population viability is the likelihood that a population will be able to maintain itself (remain viable) over a long period of time-usually 100 years or more. Though it is true...

  3. Fluorescence microscopy.

    Science.gov (United States)

    Sanderson, Michael J; Smith, Ian; Parker, Ian; Bootman, Martin D

    2014-10-01

    Fluorescence microscopy is a major tool with which to monitor cell physiology. Although the concepts of fluorescence and its optical separation using filters remain similar, microscope design varies with the aim of increasing image contrast and spatial resolution. The basics of wide-field microscopy are outlined to emphasize the selection, advantages, and correct use of laser scanning confocal microscopy, two-photon microscopy, scanning disk confocal microscopy, total internal reflection, and super-resolution microscopy. In addition, the principles of how these microscopes form images are reviewed to appreciate their capabilities, limitations, and constraints for operation. © 2014 Cold Spring Harbor Laboratory Press.

  4. Atomic theories

    CERN Document Server

    Loring, FH

    2014-01-01

    Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec

  5. Identifying protein domains by global analysis of soluble fragment data.

    Science.gov (United States)

    Bulloch, Esther M M; Kingston, Richard L

    2014-11-15

    The production and analysis of individual structural domains is a common strategy for studying large or complex proteins, which may be experimentally intractable in their full-length form. However, identifying domain boundaries is challenging if there is little structural information concerning the protein target. One experimental procedure for mapping domains is to screen a library of random protein fragments for solubility, since truncation of a domain will typically expose hydrophobic groups, leading to poor fragment solubility. We have coupled fragment solubility screening with global data analysis to develop an effective method for identifying structural domains within a protein. A gene fragment library is generated using mechanical shearing, or by uracil doping of the gene and a uracil-specific enzymatic digest. A split green fluorescent protein (GFP) assay is used to screen the corresponding protein fragments for solubility when expressed in Escherichia coli. The soluble fragment data are then analyzed using two complementary approaches. Fragmentation "hotspots" indicate possible interdomain regions. Clustering algorithms are used to group related fragments, and concomitantly predict domain location. The effectiveness of this Domain Seeking procedure is demonstrated by application to the well-characterized human protein p85α. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Nucleic acid encoding a self-assembling split-fluorescent protein system

    Energy Technology Data Exchange (ETDEWEB)

    Waldo, Geoffrey S.; Cabantous, Stephanie

    2015-07-14

    The invention provides a protein labeling and detection system based on self-complementing fragments of fluorescent and chromophoric proteins. The system of the invention is exemplified with various combinations of self-complementing fragments derived from Aequorea victoria Green Fluorescent Protein (GFP), which are used to detect and quantify protein solubility in multiple assay formats, both in vitro and in vivo.

  7. Nucleic acid encoding a self-assembling split-fluorescent protein system

    Science.gov (United States)

    Waldo, Geoffrey S [Santa Fe, NM; Cabantous, Stephanie [Los Alamos, NM

    2011-06-07

    The invention provides a protein labeling and detection system based on self-complementing fragments of fluorescent and chromophoric proteins. The system of the invention is exemplified with various combinations of self-complementing fragments derived from Aequorea victoria Green Fluorescent Protein (GFP), which are used to detect and quantify protein solubility in multiple assay formats, both in vitro and in vivo.

  8. Nucleic acid encoding a self-assembling split-fluorescent protein system

    Science.gov (United States)

    Waldo, Geoffrey S; Cabantous, Stephanie

    2014-04-01

    The invention provides a protein labeling and detection system based on self-complementing fragments of fluorescent and chromophoric proteins. The system of the invention is exemplified with various combinations of self-complementing fragments derived from Aequorea victoria Green Fluorescent Protein (GFP), which are used to detect and quantify protein solubility in multiple assay formats, both in vitro and in vivo.

  9. Atomic Power

    African Journals Online (AJOL)

    Atomic Power. By Denis Taylor: Dr. Taylor was formerly Chief UNESCO Advisor at the University. College, Nairobi, Kenya and is now Professor of Electrical Engineering in the Uni- versity of ... method of producing radioactive isotopes, which are materials .... the sealing and the pressure balancing, all can be carried out ...

  10. A turn-on fluorescence-sensing technique for glucose determination based on graphene oxide-DNA interaction.

    Science.gov (United States)

    Zhang, Hao; Huang, Hui; Lin, Zihan; Su, Xingguang

    2014-11-01

    Graphene is a two-dimensional carbon nanomaterial one atom thick. Interactions between graphene oxide (GO) and ssDNA containing different numbers of bases have been proved to be remarkably different. In this paper we propose a novel approach for turn-on fluorescence sensing determination of glucose. Hydrogen peroxide (H2O2) is produced by glucose oxidase-catalysed oxidation of glucose. In the presence of ferrous iron (Fe(2+)) the hydroxyl radical (•OH) is generated from H2O2 by the Fenton reaction. This attacks FAM-labelled long ssDNA causing irreversible cleavage, as a result of the oxidative effect of •OH, producing an FAM-linked DNA fragment. Because of the weak interaction between GO and short FAM-linked DNA fragments, restoration of DNA fluorescence can be achieved by addition of glucose. Due to the excellent fluorescence quenching efficiency of GO and the specific catalysis of glucose oxidase, the sensitivity and selectivity of this method for GO-DNA sensing are extremely high. The linear range is from 0.5 to 10 μmol L(-1) and the detection limit for glucose is 0.1 μmol L(-1). The method has been successfully used for analysis of glucose in human serum.

  11. Heavy-Quark Fragmentation

    CERN Document Server

    Cacciari, M; Cacciari, Matteo; Gardi, Einan

    2003-01-01

    We study perturbative and non-perturbative aspects of heavy-quark fragmentation into hadrons, emphasizing the large-x region, where x is the energy fraction of the detected hadron. We first prove that when the moment index N and the quark mass m get large simultaneously with the ratio (N Lambda/m) fixed, the fragmentation function depends on this ratio alone. This opens up the way to formulate the non-perturbative contribution to the fragmentation function at large N as a shape function of m(1-x) which is convoluted with the Sudakov-resummed perturbative result. We implement this resummation and the parametrization of the corresponding shape function using Dressed Gluon Exponentiation. The Sudakov exponent is calculated in a process independent way from a generalized splitting function which describes the emission probability of an off-shell gluon off a heavy quark. Non-perturbative corrections are parametrized based on the renormalon structure of the Sudakov exponent. They appear in moment space as an expone...

  12. Fracture, failure, and fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Dienes, J.K.

    1984-01-01

    Though continuum descriptions of material behavior are useful for many kinds of problems, particularly those involving plastic flow, a more general approach is required when the failure is likely to involve growth and coalescence of a large number of fractures, as in fragmentation. Failures of this kind appear frequently in rapid dynamic processes such as those resulting from impacts and explosions, particularly in the formation of spall fragments. In the first part of this paper an approach to formulating constitutive relations that accounts for the opening, shear and growth of an ensemble of cracks is discussed. The approach also accounts for plastic flow accompanying fragmentation. The resulting constitutive relations have been incorporated into a Lagrangean computer program. In the second part of this paper a theoretical approach to coalescence is described. The simplest formulation makes use of a linear Liouville equation, with crack growth limited by the mean free path of cracks, assumed constant. This approach allows for an anisotropic distribution of cracks. An alternative approach is also described in which the decrease of the mean free path with increasing crack size is accounted for, but the crack distribution is assumed isotropic. A reduction of the governing Liouville equation to an ordinary differential equation of third order is possible, and the result can be used to determine how mean-free-path decreases with increasing crack size.

  13. Ecosystem extent and fragmentation

    Science.gov (United States)

    Sayre, Roger; Hansen, Matt

    2017-01-01

    One of the candidate essential biodiversity variable (EBV) groups described in the seminal paper by Pereira et al. (2014) concerns Ecosystem Structure. This EBV group is distinguished from another EBV group which encompasses aspects of Ecosystem Function. While the Ecosystem Function EBV treats ecosystem processes like nutrient cycling, primary production, trophic interactions, etc., the Ecosystem Structure EBV relates to the set of biophysical properties of ecosystems that create biophysical environmental context, confer biophysical structure, and occur geographically. The Ecosystem Extent and Fragmentation EBV is one of the EBVs in the Ecosystem Structure EBV group.Ecosystems are understood to exist at multiple scales, from very large areas (macro-ecosystems) like the Arctic tundra, for example, to something as small as a tree in an Amazonian rain forest. As such, ecosystems occupy space and therefore can be mapped across any geography of interest, whether that area of interest be a site, a nation, a region, a continent, or the planet. One of the most obvious and seemingly straightforward EBVs is Ecosystem Extent and Fragmentation. Ecosystem extent refers to the location and geographic distribution of ecosystems across landscapes or in the oceans, while ecosystem fragmentation refers to the spatial pattern and connectivity of ecosystem occurrences on the landscape.

  14. Atomic arias

    Science.gov (United States)

    Crease, Robert P.

    2009-01-01

    The American composer John Adams uses opera to dramatize controversial current events. His 1987 work Nixon in China was about the landmark meeting in 1972 between US President Richard Nixon and Chairman Mao Zedong of China; The Death of Klinghoffer (1991) was a musical re-enactment of an incident in 1985 when Palestinian terrorists kidnapped and murdered a wheelchair-bound Jewish tourist on a cruise ship. Adams's latest opera, Doctor Atomic, is also tied to a controversial event: the first atomic-bomb test in Alamogordo, New Mexico, on 16 June 1945. The opera premièred in San Francisco in 2005, had a highly publicized debut at the Metropolitan Opera in New York in 2008, and will have another debut on 25 February - with essentially the same cast - at the English National Opera in London.

  15. Atomic rivals

    Energy Technology Data Exchange (ETDEWEB)

    Goldschmidt, B.

    1990-01-01

    This book is a memoir of rivalries among the Allies over the bomb, by a participant and observer. Nuclear proliferation began in the uneasy wartime collaboration of the United States, England, Canada, and Free France to produce the atom bomb. Through the changes of history, a young French chemist had a role in almost every act of this international drama. This memoir is based on Goldschmidt's own recollections, interviews with other leading figures, and 3,000 pages of newly declassified documents in Allied archives. From his own start as Marie Curie's lab assistant, Goldschmidt's career was closely intertwined with Frances complicated rise to membership in the nuclear club. As a refugee from the Nazis, he became part of the wartime nuclear energy project in Canada and found himself the only French scientist to work (although briefly) on the American atom bomb project.

  16. Ultrasensitive fluorescence detection of DNA

    Energy Technology Data Exchange (ETDEWEB)

    Mathies, R.A.; Glazer, A.N.

    1992-01-01

    We have shown that a number of polycationic highly fluorescent dyes form complexes with double-stranded DNA (dsDNA) which are stable to electrophoresis and have characterized in detail such dsDNA complexes with TOTO (1,1[prime]-(4,4,7,7-tetramethyl-4,7-diazaundecamethylene)-bis-4-[3-methyl-2,3-dihydro-(benzo-1,3-thiazole)-2-methylidene]-quinolinium tetraiodide) and oxazole yellow dimer (YOYO; an analogue of TOTO with a benzo-1,3-oxazole in place of the benzo-1,3-thiazole). TOTO and YOYO are virtually non-fluorescent in solution, but form highly fluorescent complexes with dsDNA, up to a maximum dye to DNA bp ratio of 1:4, with >1000-fold fluorescence enhancement. We have developed an assay using YOYO for the quantitation of single-stranded and dsDNA in solution applicable over a range of DNA concentrations from 0.5 to 100 ng per ml. The fluorescent dsDNA-dye complexes allow detection of dsDNA on agarose and acrylamide gels with picogram sensitivity. We have applied these complexes in multiplex mapping experiments for accurate sizing and quantitation of restriction fragments. We have shown that in gel shift experiments the stable dsDNA-dye complexes can be used to detect heteroduplex-Muts complexes with a sensitivity comparable to radioisotopic detection.

  17. CONTROL OF FRAGMENTATION BY BLASTING

    OpenAIRE

    Božić, Branko

    1998-01-01

    The degree of fragmentation influences the economy of the excavation operations. Characteristics of blasted rock such as fragment size, volume and mass are fundamental variables effecting the economics of a mining operation and are in effect the basis for evaluating the quality of a blast. The properties of fragmentation, such as size and shape, are very important information for the optimization of production. Three factors control the fragment size distribution: the rock structure, the q...

  18. SCALING AND 4-QUARK FRAGMENTATION

    NARCIS (Netherlands)

    SCHOLTEN, O; BOSVELD, GD

    1991-01-01

    The conditions for a scaling behaviour from the fragmentation process leading to slow protons are discussed- The scaling referred to implies that the fragmentation functions depend on the light-cone momentum fraction only. It is shown that differences in the fragmentation functions for valence- and

  19. Delivery of gene-expressing fragments using quantum dot

    Science.gov (United States)

    Hoshino, Akiyoshi; Manabe, Noriyoshi; Hanada, Sanshiro; Fujioka, Kouki; Yasuhara, Masato; Kondo, Akihiko; Yamamoto, Kenji

    2009-02-01

    Gene therapy is an attractive approach to supplement a deficient gene function. Although there has been some success with specific gene delivery using various methods including viral vectors and liposomes, most of these methods have a limited efficiency or also carry a risk for oncogenesis. Fluorescent nanoparticles, such as nanocrystal quantum dots (QDs), have potential to be applied to molecular biology and bioimaging, since some nanocrystals emit higher and longer lasting fluorescence than conventional organic probes do. We herein report that quantum dots (QDs) conjugated with nuclear localizing signal peptides (NLSP) successfully introduced the gene-fragments with promoter elements, which promoted the expression of the enhanced green fluorescent protein (eGFP) gene in mammalian cells. The expression of eGFP protein was observed when the QD/geneconstruct was added to the culture media. The gene-expression efficiency varied depending on multiple factors around QDs, such as 1) the reading direction of gene fragments, 2) the quantity of gene fragments attached on the surface of QD-constructs, 3) the surface electronic charges varied according to the structure of QD/gene-constructs, and 4) the particle size of QD/gene complex varied according to the structure and amounts of gene fragments. Using this QD/geneconstruct system, eGFP protein could be detected 28 days after the gene-introduction whereas the fluorescence of QDs was disappeared. This system therefore provides another method for the intracellular delivery of gene-fragments without using either viral vectors or specific liposomes. These results suggest that inappropriate treatment and disposal of QDs may still have risks to the environmental pollution including human health under certain conditions. Here we propose the further research for the immune and physiological responses in not only immune cells but also other cells, in order to clear the effect of all other nanoscale products as well as nanocrystal

  20. Synthesis of arabinoxylan fragments

    DEFF Research Database (Denmark)

    Underlin, Emilie Nørmølle; Böhm, Maximilian F.; Madsen, Robert

    The cell wall of plants can be termed the skeleton of the plant. One of the parts making up the cell wall is hemicellulose. Hemicellulose is composed of a number of saccharides where one of the most abundant are the arabinoxylan-oligosaccharides. In many instances the biosynthesis and degration...... of arabinoxylan oligosaccharides remain elusive. As a consequence defined arabinoxylan fragments have been chosen as synthetic targets which subsequently will be submitted to enzymatic studies. A better understanding of these processes could lead to e.g. better utilisation of the biomass for biofuel production...

  1. An Archeology of Fragments

    Directory of Open Access Journals (Sweden)

    Gerald L. Bruns

    2014-10-01

    Full Text Available This is a short (fragmentary history of fragmentary writing from the German Romantics (F. W. Schlegel, Friedrich Hölderlin to modern and contemporary concrete or visual poetry. Such writing is (often deliberately a critique of the logic of subsumption that tries to assimilate whatever is singular and irreducible into totalities of various categorical or systematic sorts. Arguably, the fragment (parataxis is the distinctive feature of literary Modernism, which is a rejection, not of what precedes it, but of what Max Weber called “the rationalization of the world” (or Modernity whose aim is to keep everything, including all that is written, under surveillance and control.

  2. Mercury speciation by high-performance liquid chromatography atomic fluorescence spectrometry using an integrated microwave/UV interface. Optimization of a single step procedure for the simultaneous photo-oxidation of mercury species and photo-generation of Hg{sup 0}

    Energy Technology Data Exchange (ETDEWEB)

    Quadros, Daiane P.C. de [Departamento de Química, Universidade Federal de Santa Catarina, 88040-970 Florianópolis, SC (Brazil); Campanella, Beatrice; Onor, Massimo; Bramanti, Emilia [National Research Council of Italy, C.N.R., Instituto di Chimica dei Composti Organo Metallici – ICCOM – UOS Pisa, Area della Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy); Borges, Daniel L.G. [Departamento de Química, Universidade Federal de Santa Catarina, 88040-970 Florianópolis, SC (Brazil); D' Ulivo, Alessandro, E-mail: dulivo@pi.iccom.cnr.it [National Research Council of Italy, C.N.R., Instituto di Chimica dei Composti Organo Metallici – ICCOM – UOS Pisa, Area della Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy)

    2014-11-01

    We described the hyphenation of photo-induced chemical vapor generation with high performance liquid chromatography–atomic fluorescence spectrometry (HPLC–AFS) for the quantification of inorganic mercury, methylmercury (MeHg) and ethylmercury (EtHg). In the developed procedure, formic acid in mobile phase was used for the photodecomposition of organomercury compounds and reduction of Hg{sup 2+} to mercury vapor under microwave/ultraviolet (MW/UV) irradiation. We optimized the proposed method studying the influence of several operating parameters, including the type of organic acid and its concentration, MW power, composition of HPLC mobile phase and catalytic action of TiO{sub 2} nanoparticles. Under the optimized conditions, the limits of detection were 0.15, 0.15 and 0.35 μg L{sup −1} for inorganic mercury, MeHg and EtHg, respectively. The developed method was validated by determination of the main analytical figures of merit and applied to the analysis of three certified reference materials. The online interfacing of liquid chromatography with photochemical-vapor generation–atomic fluorescence for mercury determination is simple, environmentally friendly, and represents an attractive alternative to the conventional tetrahydroborate (THB) system. - Highlights: • Inorganic and organic mercury were determined by photochemical vapor generation using a MW/UV photochemical reactor. • The optimized procedure has been applied to the speciation of Hg(II), MeHg and EtHg coupling HPLC with PVG–AFS. • The proposed method is simple, sensitive, and is established for mercury determination in biological materials.

  3. Fragmentation of Chitosan by Acids

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Kasaai

    2013-01-01

    Full Text Available 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.

  4. A molecular fragment cheminformatics roadmap for mesoscopic simulation.

    Science.gov (United States)

    Truszkowski, Andreas; Daniel, Mirco; Kuhn, Hubert; Neumann, Stefan; Steinbeck, Christoph; Zielesny, Achim; Epple, Matthias

    2014-12-01

    Mesoscopic simulation studies the structure, dynamics and properties of large molecular ensembles with millions of atoms: Its basic interacting units (beads) are no longer the nuclei and electrons of quantum chemical ab-initio calculations or the atom types of molecular mechanics but molecular fragments, molecules or even larger molecular entities. For its simulation setup and output a mesoscopic simulation kernel software uses abstract matrix (array) representations for bead topology and connectivity. Therefore a pure kernel-based mesoscopic simulation task is a tedious, time-consuming and error-prone venture that limits its practical use and application. A consequent cheminformatics approach tackles these problems and provides solutions for a considerably enhanced accessibility. This study aims at outlining a complete cheminformatics roadmap that frames a mesoscopic Molecular Fragment Dynamics (MFD) simulation kernel to allow its efficient use and practical application. The molecular fragment cheminformatics roadmap consists of four consecutive building blocks: An adequate fragment structure representation (1), defined operations on these fragment structures (2), the description of compartments with defined compositions and structural alignments (3), and the graphical setup and analysis of a whole simulation box (4). The basis of the cheminformatics approach (i.e. building block 1) is a SMILES-like line notation (denoted fSMILES) with connected molecular fragments to represent a molecular structure. The fSMILES notation and the following concepts and methods for building blocks 2-4 are outlined with examples and practical usage scenarios. It is shown that the requirements of the roadmap may be partly covered by already existing open-source cheminformatics software. Mesoscopic simulation techniques like MFD may be considerably alleviated and broadened for practical use with a consequent cheminformatics layer that successfully tackles its setup subtleties and

  5. N/z Dependence of Projectile Fragmentation

    Science.gov (United States)

    Trautmann, W.; Adrich, P.; Aumann, T.; Bacri, C. O.; Barczyk, T.; Bassini, R.; Bianchin, S.; Boiano, C.; Botvina, A. S.; Boudard, A.; Brzychczyk, J.; Chbihi, A.; Cibor, J.; Czech, B.; de Napoli, M.; Ducret, J.-É.; Emling, H.; Frankland, J. D.; Hellström, M.; Henzlova, D.; Immè, G.; Iori, I.; Johansson, H.; Kezzar, K.; Lafriakh, A.; Le Fèvre, A.; Le Gentil, E.; Leifels, Y.; Lühning, J.; Łukasik, J.; Lynch, W. G.; Lynen, U.; Majka, Z.; Mocko, M.; Müller, W. F. J.; Mykulyak, A.; Orth, H.; Otte, A. N.; Palit, R.; Pawłowski, P.; Pullia, A.; Raciti, G.; Rapisarda, E.; Sann, H.; Schwarz, C.; Sfienti, C.; Simon, H.; Sümmerer, K.; Tsang, M. B.; Verde, G.; Volant, C.; Wallace, M.; Weick, H.; Wiechula, J.; Wieloch, A.; Zwiegliński, B.

    The N/Z dependence of projectile fragmentation at relativistic energies has been studied in a recent experiment at the GSI laboratory with the ALADiN forward spectrometer coupled to the LAND neutron detector. Besides a primary beam of 124Sn, also secondary beams of 124La and 107Sn delivered by the FRS fragment separator have been used in order to extend the range of isotopic compositions of the produced spectator sources. With the achieved mass resolution of ΔA/A ≈ 1.5%, lighter isotopes with atomic numbers Z ≤ 10 are individually resolved. The presently ongoing analyses of the measured isotope yields focus on isoscaling and its relation to the properties of hot fragments at freeze-out and on the derivation of chemical freeze-out temperatures which are found to be independent of the isotopic composition of the studied systems. The latter result is at variance with the predictions for limiting temperatures as obtained with finite-temperature Hartree-Fock calculations.

  6. Atom Skimmers and Atom Lasers Utilizing Them

    Science.gov (United States)

    Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

    2005-01-01

    Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

  7. Quantum Correlated Multi-Fragment Reaction Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Feagin, James M. [California State Univ., Fullerton, CA (United States)

    2017-06-30

    This grant supported research in basic atomic, molecular and optical physics related to the interactions of atoms with particles and fields. This report will focus on the 12 year period from 2004 to 2017, although the DOE–BES has supported my research every year since 1986. All of the support from the grant was used to pay summer salaries of the PI and students and travel to conferences and meetings. The results were in the form of publications in peer reviewed journals as well as conference invited talks and colloquiums. There were 12 peer reviewed publications in these 12+ years. Innovations in few-body science at molecular and nano levels are a critical component of on- going efforts to establish sustainable environmental and energy resources. The varied research paths taken will require the development of basic science on broad fronts with increasing flexi- bility to crossover technologies. We thus worked to extract understanding and quantum control of few-body microscopic systems based on our long-time experience with more conventional studies of correlated electrons and ions. Given the enormous advances over the past 20 years to our understanding of quantum cor- relations with photon interferometry, AMO collision science generally is ready to move beyond the one-particle, single-port momentum detection that has dominated collision physics since Rutherford. Nevertheless, our familiar theoretical tools for collision theory need to be up- graded to incorporate these more generalized measurement formalisms and ultimately to give incentive for a new generation of experiments. Our interest in these topics remains motivated by the recent surge in and success of exper- iments involving few-body atomic and molecular fragmentation and the detection of all the fragments. The research described here thus involved two parallel efforts with (i) emphasis on reaction imaging while (ii) pursuing longtime work on quantum correlated collective excitations.

  8. Cold Light from Hot Atoms and Molecules

    Science.gov (United States)

    Lister, Graeme; Curry, John J.

    2011-05-01

    The introduction of rare earth atoms and molecules into lighting discharges led to great advances in efficacy of these lamps. Atoms such as Dy, Ho and Ce provide excellent radiation sources for lighting applications, with rich visible spectra, such that a suitable combination of these elements can provide high quality white light. Rare earth molecules have also proved important in enhancing the radiation spectrum from phosphors in fluorescent lamps. This paper reviews some of the current aspects of lighting research, particularly rare earth chemistry and radiation, and the associated fundamental atomic and molecular data.

  9. Evaluation of chemical fluorescent dyes as a protein conjugation partner for live cell imaging.

    Directory of Open Access Journals (Sweden)

    Yoko Hayashi-Takanaka

    Full Text Available To optimize live cell fluorescence imaging, the choice of fluorescent substrate is a critical factor. Although genetically encoded fluorescent proteins have been used widely, chemical fluorescent dyes are still useful when conjugated to proteins or ligands. However, little information is available for the suitability of different fluorescent dyes for live imaging. We here systematically analyzed the property of a number of commercial fluorescent dyes when conjugated with antigen-binding (Fab fragments directed against specific histone modifications, in particular, phosphorylated H3S28 (H3S28ph and acetylated H3K9 (H3K9ac. These Fab fragments were conjugated with a fluorescent dye and loaded into living HeLa cells. H3S28ph-specific Fab fragments were expected to be enriched in condensed chromosomes, as H3S28 is phosphorylated during mitosis. However, the degree of Fab fragment enrichment on mitotic chromosomes varied depending on the conjugated dye. In general, green fluorescent dyes showed higher enrichment, compared to red and far-red fluorescent dyes, even when dye:protein conjugation ratios were similar. These differences are partly explained by an altered affinity of Fab fragment after dye-conjugation; some dyes have less effect on the affinity, while others can affect it more. Moreover, red and far-red fluorescent dyes tended to form aggregates in the cytoplasm. Similar results were observed when H3K9ac-specific Fab fragments were used, suggesting that the properties of each dye affect different Fab fragments similarly. According to our analysis, conjugation with green fluorescent dyes, like Alexa Fluor 488 and Dylight 488, has the least effect on Fab affinity and is the best for live cell imaging, although these dyes are less photostable than red fluorescent dyes. When multicolor imaging is required, we recommend the following dye combinations for optimal results: Alexa Fluor 488 (green, Cy3 (red, and Cy5 or CF640 (far-red.

  10. CONTROL OF FRAGMENTATION BY BLASTING

    Directory of Open Access Journals (Sweden)

    Branko Božić

    1998-12-01

    Full Text Available The degree of fragmentation influences the economy of the excavation operations. Characteristics of blasted rock such as fragment size, volume and mass are fundamental variables effecting the economics of a mining operation and are in effect the basis for evaluating the quality of a blast. The properties of fragmentation, such as size and shape, are very important information for the optimization of production. Three factors control the fragment size distribution: the rock structure, the quantity of explosive and its distribution within the rock mass. Over the last decade there have been considerable advances in our ability to measure and analyze blasting performance. These can now be combined with the continuing growth in computing power to develop a more effective description of rock fragmentation for use by future blasting practitioners. The paper describes a view of the fragmentation problem by blasting and the need for a new generation of engineering tools to guide the design and implementation of blasting operations.

  11. High Atom Number in Microsized Atom Traps

    Science.gov (United States)

    2015-12-14

    Final Performance Report on ONR Grant N00014-12-1-0608 High atom number in microsized atom traps for the period 15 May 2012 through 14 September...TYPE Final Technical Report 3. DATES COVERED (From - To) 05/15/2012-09/14/2012 4. TITLE AND SUBTITLE High atom number in microsized atom traps...forces for implementing a small-footprint, large-number atom -chip instrument. Bichromatic forces rely on absorption and stimulated emission to produce

  12. Introduction to fluorescence microscopy.

    Science.gov (United States)

    Ghiran, Ionita C

    2011-01-01

    This chapter is an overview of basic principles of fluorescence microscopy, including a brief history on the invention of this type of microscopy. The chapter highlights important points related to properties of fluorochromes, resolution in fluorescence microscopy, phase contrast and fluorescence, fluorescence filters, construction of a fluorescence microscope, and tips on the correct use of this equipment.

  13. Impact of Linker Length and Composition on Fragment Binding and Cell Permeation: Story of a Bisbenzimidazole Dye Fragment.

    Science.gov (United States)

    Ranjan, Nihar; Kellish, Patrick; King, Ada; Arya, Dev P

    2017-12-12

    Small molecules that modulate biological functions are targets of modern day drug discovery efforts. In a common platform fragment-based drug discovery, two fragments that bind to adjacent sites on a target are identified and are then linked together using different linkers to identify the linkage for optimum activity. What are not known from these studies are the effects these linkers, which typically contain C, H, and O atoms, have on the properties of the individual fragment. Herein, we investigate such effects in a bisbenzimidazole fragment whose derivatives have a wide range of therapeutic applications in nucleic acid recognition, sensing, and photodynamic therapy and as cellular probes. We report a dramatic effect of linker length and composition of alkynyl (clickable) Hoechst 33258 derivatives in target binding and cell uptake. We show that the binding of Hoechst 33258-modeled bisbenzimidazoles (1-9) that contain linkers of varying lengths (3-21 atoms) display length- and composition-dependent variation in B-DNA stabilization using a variety of spectroscopic methods. For a dodecamer DNA duplex, the thermal stabilization varied from 0.3 to 9.0 °C as the linker length increased from 3 to 21 atoms, respectively. Compounds with linker lengths of ≤11 atoms (such as compounds 1 and 5) are localized in the nucleus, while compounds with long linkers (such as compounds 8 and 9) are distributed in the extranuclear space, as well, with possible interactions with extranuclear targets. These findings provide insights into future drug design by revealing how linkers can influence the biophysical and cellular properties of individual drug fragments.

  14. An Algebra for Program Fragments

    DEFF Research Database (Denmark)

    Kristensen, Bent Bruun; Madsen, Ole Lehrmann; Møller-Pedersen, Birger

    1985-01-01

    Program fragments are described either by strings in the concrete syntax or by constructor applications in the abstract syntax. By defining conversions between these forms, both may be intermixed. Program fragments are constructed by terminal and nonterminal symbols from the grammar and by variab......Program fragments are described either by strings in the concrete syntax or by constructor applications in the abstract syntax. By defining conversions between these forms, both may be intermixed. Program fragments are constructed by terminal and nonterminal symbols from the grammar...

  15. Determination of experimental K-shell fluorescence yield for ...

    Indian Academy of Sciences (India)

    for many years and have been compiled by Krause [1], Bambynek et al [2,3] and. Hubbell et al [4,5]. Fluorescence yield, ωK, plays an important role in a variety of fields such as atomic, molecular and radiation physics, X-ray fluorescence analysis, cancer therapy, medical research, health physics, irradiation processes and ...

  16. Muscle fragments on a scaffold in rats

    DEFF Research Database (Denmark)

    Jangö, Hanna; Gräs, Søren; Christensen, Lise

    2015-01-01

    with autologous muscle fiber fragments (MFF), as an adjunct to native tissue POP repair, is a potential new alternative. METHODS: A rat abdominal wall model of native repair was used with six animals in each of three groups: native repair, native repair + MPEG-PLGA, and native repair + MPEG-PLGA + MFF. MFF were...... labeled with PKH26-fluorescence dye. After 8 weeks labeled cells were identified in tissue samples and histopathological and immunohistochemical analyses of connective tissue organization and desmin reactivity of muscle cells were performed. Fresh tissue samples were subjected to uniaxial biomechanical......-PLGA scaffolds seeded with autologous MFF affected some histological and biomechanical properties of native tissue repair in an abdominal wall defect model in rats. The method thus appears to be a simple tissue engineering concept with potential relevance for native tissue repair of POP....

  17. Fluorescence detection: SPIE volume 743

    Energy Technology Data Exchange (ETDEWEB)

    Menzel, E.R.

    1987-01-01

    This book contains proceedings arranged into four sessions. They are: Fluorescence spectroscopic techniques; Fluorescence in analysis and materials characterization; Fluorescence in medicine and biochemistry; and Fluorescence in criminalistics.

  18. Dynamics Resonances in Atomic States of Astrophysical Relevance

    Indian Academy of Sciences (India)

    Since spontaneous fluorescence of excited atoms is probabilistic, the description of the radiating quantized system evolution along with photon energy transfer in a cold atom medium, should include elements of stochastic dynamics. Finally, the chaotic dynamics of a weakly bound Rydberg electron over a grid of the energy ...

  19. Barium transport in fluorescent lamps

    Science.gov (United States)

    Sigeneger, F.; Rackow, K.; Uhrlandt, D.; Ehlbeck, J.; Lieder, G.

    2008-10-01

    The transport of barium atoms and ions in the cathode region of fluorescent lamps driven at 25,Hz is studied experimentally and theoretically. The density of Ba atoms and ions have been measured time-resolved by laserinduced fluorescence at different distances from the spot center. Furthermore, the time-dependent cathode fall voltage was approximately determined using an improved band method. The model comprises the solution of the time-dependent particle balance equations of Ba and Ba^+ which include the Ba ionization as gain and loss terms, respectively. The ionization rate coefficient of Ba and the electron density are determined by solving the space-dependent electron Boltzmann equation in spherical geometry using the measured cathode fall voltage and the discharge current as input. Good agreement between the measured and calculated density profiles of barium atoms has been obtained. The results demonstrate the sensitive dependence of the Ba density profiles on the ionization which leads to a strong depletion of the Ba density in the cathode phase of the investigated electrode. The model yields the Ba flux from the cathode which limits the lifetime of the lamp.

  20. Thermodynamical string fragmentation

    Science.gov (United States)

    Fischer, Nadine; Sjöstrand, Torbjörn

    2017-01-01

    The observation of heavy-ion-like behaviour in pp collisions at the LHC suggests that more physics mechanisms are at play than traditionally assumed. The introduction e.g. of quark-gluon plasma or colour rope formation can describe several of the observations, but as of yet there is no established paradigm. In this article we study a few possible modifications to the Pythia event generator, which describes a wealth of data but fails for a number of recent observations. Firstly, we present a new model for generating the transverse momentum of hadrons during the string fragmentation process, inspired by thermodynamics, where heavier hadrons naturally are suppressed in rate but obtain a higher average transverse momentum. Secondly, close-packing of strings is taken into account by making the temperature or string tension environment-dependent. Thirdly, a simple model for hadron rescattering is added. The effect of these modifications is studied, individually and taken together, and compared with data mainly from the LHC. While some improvements can be noted, it turns out to be nontrivial to obtain effects as big as required, and further work is called for.

  1. Energy distribution of projectile fragment particles in heavy ion therapeutic beam

    Energy Technology Data Exchange (ETDEWEB)

    Matsufuji, Naruhiro; Tomura, Hiromi; Futami, Yasuyuki [National Inst. of Radiological Sciences, Chiba (Japan)] [and others

    1998-03-01

    Production of fragment particles in a patient`s body is one of important problems for heavy charged particle therapy. It is required to know the yield and the energy spectrum for each fragment element - so called `beam quality` to understand the effect of therapeutic beam precisely. In this study, fragment particles produced by practical therapeutic beam of HIMAC were investigated with using tissue-equivalent material and a detector complex. From the results, fragment particles were well identified by difference of their atomic numbers and the beam quality was derived. Responses of the detectors in this energy region were also researched. (author)

  2. Fragmentation of exotic oxygen isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Leistenschneider, A.; Elze, Th.W.; Gruenschloss, A.; Palit, R. [Johann Wolfgang Goethe-Univ., Frankfurt (Germany). Inst. fuer Kernphysik; Aumann, T.; Cortina, D.; Datta Pramanik, U.; Emling, H.; Geissel, H.; Helariutta, K.; Hellstroem, M.; Ilievski, S.; Jones, K.; Muenzenberg, G.; Scheidenberger, C.; Schmidt, K.-H.; Suemmerer, K. [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); Boretzky, K.; Kratz, J.V.; Le Hong, Khiem [Johannes Gutenberg-Univ., Mainz (Germany). Inst. fue Kernchemie; Canto, L.F. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Fisica; Carlson, B.V. [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil). Inst. Tecnologico de Aeronautica (ITA). Dept. de Fisica; Hussein, M.S. [Sao Paulo Univ. (USP), SP (Brazil). Inst. de Fisica; Kulessa, R.; Lubkiewicz, E.; Wajda, E.; Walus, W. [Uniwersytet Jagellonski, Krakow (Poland). Instytut Fizyki; Reiter, P. [Ludwig-Maximilians-Univ., Garching (Germany). Sektion Physik; Simon, H. [Technische Univ., Darmstadt (Germany). Inst. fuer Kernphysik

    2003-06-01

    Abrasion-ablation models and the empirical EPAX parametrization of projectile fragmentation are described. Their cross section predictions are compared to recent data of the fragmentation of secondary beams of neutron-rich, unstable {sup 19,20,21} O isotopes at beam energies near 600 MeV/nucleon as well as data for stable {sup 17,18} O beams. (author)

  3. Polymer fragmentation in extensional flow

    Energy Technology Data Exchange (ETDEWEB)

    Maroja, Armando M.; Oliveira, Fernando A.; Ciesla, Michal; Longa, Lech

    2001-06-01

    In this paper we present an analysis of fragmentation of dilute polymer solutions in extensional flow. The transition rate is investigated both from theoretical and computational approaches, where the existence of a Gaussian distribution for the breaking bonds has been controversial. We give as well an explanation for the low fragmentation frequency found in DNA experiments.

  4. Mass spectrometry for fragment screening.

    Science.gov (United States)

    Chan, Daniel Shiu-Hin; Whitehouse, Andrew J; Coyne, Anthony G; Abell, Chris

    2017-11-08

    Fragment-based approaches in chemical biology and drug discovery have been widely adopted worldwide in both academia and industry. Fragment hits tend to interact weakly with their targets, necessitating the use of sensitive biophysical techniques to detect their binding. Common fragment screening techniques include differential scanning fluorimetry (DSF) and ligand-observed NMR. Validation and characterization of hits is usually performed using a combination of protein-observed NMR, isothermal titration calorimetry (ITC) and X-ray crystallography. In this context, MS is a relatively underutilized technique in fragment screening for drug discovery. MS-based techniques have the advantage of high sensitivity, low sample consumption and being label-free. This review highlights recent examples of the emerging use of MS-based techniques in fragment screening. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  5. "Bohr's Atomic Model."

    Science.gov (United States)

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  6. CANAS '01 - Colloquium analytical atomic spectroscopy; CANAS '01 - Colloquium Analytische Atomspektroskopie. Programm. Kurzfassungen der Vortraege und Poster

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    The main topics of the meeting on analytical atom spectroscopy were: optical atom spectrometry, x-ray fluorescence analysis, absorption spectroscopy, icp mass spectroscopy, trace analysis, sampling, sample preparation and quality assurance.

  7. Effect of binding and conformation on fluorescence quenching in new 2',7'-dichlorofluorescein derivatives.

    Science.gov (United States)

    Sparano, Brian A; Shahi, Shatrughan P; Koide, Kazunori

    2004-06-10

    [structure: see text] Symmetrical and unsymmetrical 2',7'-dichlorofluorescein (DCF) derivatives have been synthesized by means of Mannich reactions and an aromatic Claisen rearrangement. NMR and fluorescence spectroscopic studies reveal the correlation between the conformations, the photoinduced electron transfer mechanism, and fluorescent intensities of these DCF derivatives. Two quenching nitrogen atoms cooperatively and reversibly suppress the fluorescence of the chromophore.

  8. Fluorescent bioassays for toxic metals in milk and yoghurt

    Directory of Open Access Journals (Sweden)

    Siddiki Mohammad Shohel

    2012-10-01

    Full Text Available Abstract Background From a human health viewpoint, contaminated milk and its products could be a source of long-term exposure to toxic metals. Simple, inexpensive, and on-site assays would enable constant monitoring of their contents. Bioassays that can measure toxic metals in milk or yoghurt might reduce the risk. For this purpose, the green fluorescent protein (GFP-tagged trans factors, ArsR-GFP and CadC-GFP, together with their cis elements were used to develop such bioassays. Results ArsR-GFP or CadC-GFP, which binds either toxic metal or DNA fragment including cis element, was directly mixed with cow’s milk or yoghurt within a neutral pH range. The fluorescence of GFP, which is reflected by the association/dissociation ratio between cis element and trans factor, significantly changed with increasing externally added As (III or Cd (II whereas smaller responses to externally added Pb (II and Zn (II were found. Preparation and dilution of whey fraction at low pH were essential to intrinsic zinc quantification using CadC-GFP. Using the extraction procedure and bioassay, intrinsic Zn (II concentrations ranging from 1.4 to 4.8 mg/l for milk brands and from 1.2 to 2.9 mg/kg for yoghurt brands were determined, which correlated to those determined using inductively coupled plasma atomic emission spectroscopy. Conclusions GFP-tagged bacterial trans factors and cis elements can work in the neutralized whole composition and diluted whey fraction of milk and yoghurt. The feature of regulatory elements is advantageous for establishment of simple and rapid assays of toxic metals in dairy products.

  9. Fluorescent bioassays for toxic metals in milk and yoghurt.

    Science.gov (United States)

    Siddiki, Mohammad Shohel Rana; Ueda, Shunsaku; Maeda, Isamu

    2012-10-25

    From a human health viewpoint, contaminated milk and its products could be a source of long-term exposure to toxic metals. Simple, inexpensive, and on-site assays would enable constant monitoring of their contents. Bioassays that can measure toxic metals in milk or yoghurt might reduce the risk. For this purpose, the green fluorescent protein (GFP)-tagged trans factors, ArsR-GFP and CadC-GFP, together with their cis elements were used to develop such bioassays. ArsR-GFP or CadC-GFP, which binds either toxic metal or DNA fragment including cis element, was directly mixed with cow's milk or yoghurt within a neutral pH range. The fluorescence of GFP, which is reflected by the association/dissociation ratio between cis element and trans factor, significantly changed with increasing externally added As (III) or Cd (II) whereas smaller responses to externally added Pb (II) and Zn (II) were found. Preparation and dilution of whey fraction at low pH were essential to intrinsic zinc quantification using CadC-GFP. Using the extraction procedure and bioassay, intrinsic Zn (II) concentrations ranging from 1.4 to 4.8 mg/l for milk brands and from 1.2 to 2.9 mg/kg for yoghurt brands were determined, which correlated to those determined using inductively coupled plasma atomic emission spectroscopy. GFP-tagged bacterial trans factors and cis elements can work in the neutralized whole composition and diluted whey fraction of milk and yoghurt. The feature of regulatory elements is advantageous for establishment of simple and rapid assays of toxic metals in dairy products.

  10. DNA length evaluation using cyanine dye and fluorescence correlation spectroscopy.

    Science.gov (United States)

    Shimizu, Masafumi; Sasaki, Satoshi; Tsuruoka, Makoto

    2005-01-01

    To develop a high-performance method for measuring the length of double-stranded DNA (dsDNA) fragments, the capability of fluorescence correlation spectroscopy (FCS) was examined. To omit troublesome and time-consuming labeling operations such as PCR with fluorescently labeled mononucleotides or primers, intercalation of dimeric cyanine dye YOYO-1 iodide (YOYO) to dsDNA was utilized as a simple labeling method. Various lengths of dsDNA fragments were prepared and mixed with YOYO prior to FCS, and the dependence of the diffusion time of a dsDNA-YOYO complex on the length of dsDNA fragment and the dsDNA/YOYO ratio was investigated. It was successfully demonstrated that the dsDNA length can be measured using YOYO and FCS, and the calibration curve was developed taking into account the rewinding and expansion of the dsDNA fragment caused by YOYO intercalation.

  11. Teach us atom structure

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Suh Yeon

    2006-08-15

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  12. Playing pinball with atoms.

    Science.gov (United States)

    Saedi, Amirmehdi; van Houselt, Arie; van Gastel, Raoul; Poelsema, Bene; Zandvliet, Harold J W

    2009-05-01

    We demonstrate the feasibility of controlling an atomic scale mechanical device by an external electrical signal. On a germanium substrate, a switching motion of pairs of atoms is induced by electrons that are directly injected into the atoms with a scanning tunneling microscope tip. By precisely controlling the tip current and distance we make two atom pairs behave like the flippers of an atomic-sized pinball machine. This atomic scale mechanical device exhibits six different configurations.

  13. The spectroscopy of fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, W.R. [Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)

    1998-12-31

    High-resolution measurements on {gamma} rays from fission fragments have provided a rich source of information, unobtainable at the moment in any other way, on the spectroscopy of neutron-rich nuclei. In recent years important data have been obtained on the yrast- and near yrast-structure of neutron-rich fission fragments. We discuss the scope of measurements which can be made on prompt gamma rays from secondary fission fragments, the techniques used in the experiments and some results recently obtained. (author) 24 refs., 8 figs., 1 tab.

  14. Archaeological pottery fragments analysis from Sambaqui do Bacanga (MA-Brazil) with a portable EDXRF system

    Energy Technology Data Exchange (ETDEWEB)

    Ikeoka, Renato A.; Appoloni, Carlos R.; Parreira, Paulo S.; Lopes, Fabio [Universidade Estadual de Londrina (UEL), PR (Brazil). Dept. de Fisica], e-mail: renatoikeoka@yahoo.com.br; Bandeira, Arkley M. [Universidade de Sao Paulo (USP), SP (Brazil). Museu de Arqueologia e Etnologia], e-mail: arkleybandeira@hotmail.com

    2009-07-01

    Sambaqui do Bacanga archaeological site is located in the Island of Sao Luis - Maranhao - Brazil, in the region bathed by the Bacanga River. A stratigraphic collection of 68 pottery fragments was collected during the years 2005 and 2006 to perform a qualitative analysis of the chemical elements employing a Portable System of Energy Dispersive X-ray Fluorescence (PXRF). The elements K, Ca, Ti, Mn, Fe, Zn, Br, Rb, Sr, Y, Zr and Pb were identified in the different fragments and only Fe, Ca, Sr, Zr, Mn, Ti and Zn were common elements for all of them, indicating that these elements are present in the raw material used in the manufacture of the fragments. Only one fragment presented remains of painting. A larger concentration of Fe was observed in this region compared to other areas. This indicates that a material with iron oxide was used to make the painting. The elements Fe, Sr, Mn, Ti and Zn are present, systematically, with larger intensities on concave and convex sides in relation to the ceramic paste for 43 among the 68 analyzed fragments, indicating a different surface treatment that leads to an enrichment of those elements. Cluster analysis was performed with the pottery fragments at three levels. The fragments were grouped in three different clusters, except for two fragments from the 132 cm level, which grouped with the fragments from 10-20 cm level. This result indicates three different sources of clay for the studied pottery fragments. (author)

  15. Light quark fragmentations into pions

    Science.gov (United States)

    Edemskaya, A. K.; Naumov, D. V.; Samoylov, O. B.

    2011-12-01

    We discuss a process of hadronization of light quarks into charged pions in e + e - annihilations and in deep inelastic scatering of charged leptons and neutrino off nucleons. The corresponding semi-inclusive cross-sections of pions production we write in terms of quark fragmentation functions and fracture functions. We suggest a new method of measurements of fragmentation and fracture functions based on analysis of semiinclusive data.

  16. QGP and Modified Jet Fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin-Nian

    2005-04-18

    Recent progresses in the study of jet modification in hotmedium and their consequences in high-energy heavy-ion collisions are reviewed. In particular, I will discuss energy loss for propagating heavy quarks and the resulting modified fragmentation function. Medium modification of the parton fragmentation function due to quark recombination are formulated within finite temperature field theory and their implication on the search for deconfined quark-gluon plasma is also discussed.

  17. Fundamentals of fluorescence and fluorescence microscopy.

    Science.gov (United States)

    Wolf, David E

    2013-01-01

    This chapter discusses the fundamental physics of fluorescence. The application of fluorescence to microscopy represents an important transition in the development of microscopy, particularly as it applies to biology. It enables quantitating the amounts of specific molecules within a cell, determining whether molecules are complexing on a molecular level, measuring changes in ionic concentrations within cells and organelles, and measuring molecular dynamics. This chapter also discusses the issues important to quantitative measurement of fluorescence and focuses on four of quantitative measurements of fluorescence--boxcar-gated detection, streak cameras, photon correlation, and phase modulation. Although quantitative measurement presents many pitfalls to the beginner, it also presents significant opportunities to one skilled in the art. This chapter also examines how fluorescence is measured in the steady state and time domain and how fluorescence is applied in the modern epifluorescence microscope. Copyright © 2007 Elsevier Inc. All rights reserved.

  18. In Vivo Fluorescent Detection of Fe-S Clusters Coordinated by Human GRX2

    OpenAIRE

    Hoff, Kevin G.; Culler, Stephanie J; Nguyen, Peter Q.; McGuire, Ryan M.; Silberg, Jonathan J.; Smolke, Christina D.

    2009-01-01

    A major challenge to studying Fe-S cluster biosynthesis in higher eukaryotes is the lack of simple tools for imaging metallocluster binding to proteins. We describe the first fluorescent approach for in vivo detection of 2Fe2S clusters that is based upon the complementation of Venus fluorescent protein fragments via human glutaredoxin 2 (GRX2) coordination of a 2Fe2S cluster. We show that Escherichia coli and mammalian cells expressing Venus fragments fused to GRX2 ...

  19. Control the fear atomic

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Gwan [I and Book, Seoul (Korea, Republic of)

    2003-04-15

    This book has a lot of explanation of nuclear energy with articles. Their titles are the bad man likes atomic, the secret of atom, nuclear explosion, NPT?, the secret of uranium fuel rod, nuclear power plant vs nuclear bomb, I hate atomic, keep plutonium in control, atomic in peace and find out alternative energy.

  20. Measuring Membrane Penetration with Depth-Dependent Fluorescence Quenching: Distribution Analysis is Coming of Age

    Science.gov (United States)

    Ladokhin, Alexey S.

    2014-01-01

    Depth-dependent fluorescence quenching by lipid-attached quenchers (e.g., bromine atoms or doxyl groups) is an important tool for determining the penetration of proteins and peptides into lipid bilayers. Extracting quantitative information and accurate calculations of the depth of the fluorophore are complicated by thermal disorder, resulting in broad distributions of the transverse positions of both quenchers and fluorophores. Twenty-one years ago a methodology called Distribution Analysis (DA) was introduced, based on the emerging view of the complexity of the transverse organization of lipid bilayer structure. The method is aimed at extracting quantitative information on membrane penetration, such as position and width of fluorophore's distribution along the depth coordinate and its exposure to the lipid phase. Here we review recent progress in refining the DA method and illustrate its applications to protein-membrane interactions. We demonstrate how basic assumptions of the DA approach can be validated using molecular dynamics simulations and how the precision of depth determination is improved by applying a new protocol based on a combination of steady-state and time-resolved fluorescence quenching. Using the example of the MPER fragment of the membrane-spanning domain of the HIV-1 gp41 fusion protein, we illustrate how DA applications and computer simulations can be used together to reveal the molecular organization of a protein-membrane complex. PMID:24593994

  1. Reviews in fluorescence 2010

    CERN Document Server

    Geddes, Chris D

    2011-01-01

    ""Reviews in Fluorescence 2010"", the seventh volume of the book serial from Springer, serves as a comprehensive collection of current trends and emerging hot topics in the field of fluorescence and closely related disciplines. It summarizes the year's progress in fluorescence and its applications, with authoritative analytical reviews specialized enough to be attractive to professional researchers, yet also appealing to the wider audience of scientists in related disciplines of fluorescence. ""Reviews in Fluorescence"" offers an essential reference material for any lab working in the fluoresc

  2. Principles of fluorescence techniques

    CERN Document Server

    2016-01-01

    Fluorescence techniques are being used and applied increasingly in academics and industry. The Principles of Fluorescence Techniques course will outline the basic concepts of fluorescence techniques and the successful utilization of the currently available commercial instrumentation. The course is designed for students who utilize fluorescence techniques and instrumentation and for researchers and industrial scientists who wish to deepen their knowledge of fluorescence applications. Key scientists in the field will deliver theoretical lectures. The lectures will be complemented by the direct utilization of steady-state and lifetime fluorescence instrumentation and confocal microscopy for FLIM and FRET applications provided by leading companies.

  3. Fragmentation and ablation during entry

    Energy Technology Data Exchange (ETDEWEB)

    Canavan, G.H.

    1997-09-01

    This note discusses objects that both fragment and ablate during entry, using the results of previous reports to describe the velocity, pressure, and fragmentation of entering objects. It shows that the mechanisms used there to describe the breakup of non-ablating objects during deceleration remain valid for most ablating objects. It treats coupled fragmentation and ablation during entry, building on earlier models that separately discuss the entry of objects that are hard, whose high heat of ablation permits little erosion, and those who are strong whose strength prevents fragmentation, which are discussed in ``Radiation from Hard Objects,`` ``Deceleration and Radiation of Strong, Hard, Asteroids During Atmospheric Impact,`` and ``Meteor Signature Interpretation.`` This note provides a more detailed treatment of the further breakup and separation of fragments during descent. It replaces the constraint on mass per unit area used earlier to determine the altitude and magnitude of peak power radiation with a detailed analytic solution of deceleration. Model predictions are shown to be in agreement with the key features of numerical calculations of deceleration. The model equations are solved for the altitudes of maximum radiation, which agree with numerical integrations. The model is inverted analytically to infer object size and speed from measurements of peak power and altitude to provide a complete model for the approximate inversion of meteor data.

  4. Efficient sampling in fragment-based protein structure prediction using an estimation of distribution algorithm.

    Directory of Open Access Journals (Sweden)

    David Simoncini

    Full Text Available Fragment assembly is a powerful method of protein structure prediction that builds protein models from a pool of candidate fragments taken from known structures. Stochastic sampling is subsequently used to refine the models. The structures are first represented as coarse-grained models and then as all-atom models for computational efficiency. Many models have to be generated independently due to the stochastic nature of the sampling methods used to search for the global minimum in a complex energy landscape. In this paper we present EdaFold(AA, a fragment-based approach which shares information between the generated models and steers the search towards native-like regions. A distribution over fragments is estimated from a pool of low energy all-atom models. This iteratively-refined distribution is used to guide the selection of fragments during the building of models for subsequent rounds of structure prediction. The use of an estimation of distribution algorithm enabled EdaFold(AA to reach lower energy levels and to generate a higher percentage of near-native models. [Formula: see text] uses an all-atom energy function and produces models with atomic resolution. We observed an improvement in energy-driven blind selection of models on a benchmark of EdaFold(AA in comparison with the [Formula: see text] AbInitioRelax protocol.

  5. Microfabricated Waveguide Atom Traps.

    Energy Technology Data Exchange (ETDEWEB)

    Jau, Yuan-Yu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    A nanoscale , microfabricated waveguide structure can in - principle be used to trap atoms in well - defined locations and enable strong photon-atom interactions . A neutral - atom platform based on this microfabrication technology will be prealigned , which is especially important for quantum - control applications. At present, there is still no reported demonstration of evanescent - field atom trapping using a microfabricated waveguide structure. We described the capabilities established by our team for future development of the waveguide atom - trapping technology at SNL and report our studies to overcome the technical challenges of loading cold atoms into the waveguide atom traps, efficient and broadband optical coupling to a waveguide, and the waveguide material for high - power optical transmission. From the atomic - physics and the waveguide modeling, w e have shown that a square nano-waveguide can be utilized t o achieve better atomic spin squeezing than using a nanofiber for first time.

  6. Atomic and molecular manipulation

    CERN Document Server

    Mayne, Andrew J

    2011-01-01

    Work with individual atoms and molecules aims to demonstrate that miniaturized electronic, optical, magnetic, and mechanical devices can operate ultimately even at the level of a single atom or molecule. As such, atomic and molecular manipulation has played an emblematic role in the development of the field of nanoscience. New methods based on the use of the scanning tunnelling microscope (STM) have been developed to characterize and manipulate all the degrees of freedom of individual atoms and molecules with an unprecedented precision. In the meantime, new concepts have emerged to design molecules and substrates having specific optical, mechanical and electronic functions, thus opening the way to the fabrication of real nano-machines. Manipulation of individual atoms and molecules has also opened up completely new areas of research and knowledge, raising fundamental questions of "Optics at the atomic scale", "Mechanics at the atomic scale", Electronics at the atomic scale", "Quantum physics at the atomic sca...

  7. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    2000-01-01

    This fifth volume of the successful series Advances in Atomic Spectroscopy continues to discuss and investigate the area of atomic spectroscopy.It begins with a description of the use of various atomic spectroscopic methods and applications of speciation studies in atomic spectroscopy. The emphasis is on combining atomic spectroscopy with gas and liquid chromatography. In chapter two the authors describe new developments in tunable lasers and the impact they will have on atomic spectroscopy. The traditional methods of detection, such as photography and the photomultiplier, and how they are being replaced by new detectors is discussed in chapter three. The very active area of glow discharge atomic spectrometry is presented in chapter four where, after a brief introduction and historical review, the use of glow discharge lamps for atomic spectroscopy and mass spectrometry are discussed. Included in this discussion is geometry and radiofrequency power. The future of this source in atomic spectroscopy is also dis...

  8. Fragments of protein A eluted during protein A affinity chromatography.

    Science.gov (United States)

    Carter-Franklin, Jayme N; Victa, Corazon; McDonald, Paul; Fahrner, Robert

    2007-09-07

    Protein A affinity chromatography is a common method for process scale purification of monoclonal antibodies. During protein A affinity chromatography, protein A ligand co-elutes with the antibody (commonly called leaching), which is a potential disadvantage since the leached protein A may need to be cleared for pharmaceutical antibodies. To determine the mechanism of protein A leaching and characterize the leached protein A, we fluorescently labeled the protein A ligand in situ on protein A affinity chromatography media. We found that intact protein A leaches when loading either purified antibody or unpurified antibody in harvested cell culture fluid (HCCF), and that additionally fragments of protein A leach when loading HCCF. The leaching of protein A fragments can be reduced by EDTA, suggesting that proteinases contribute to the generation of protein A fragments. We found that protein A fragments larger than about 6000 Da can be measured by enzyme linked immunosorbent assay, and that they can be more difficult to clear than whole protein A by cation-exchange chromatography.

  9. A thermodynamic theory of dynamic fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Yew, Ching H. [Texas Univ., Austin, TX (United States); Taylor, P.A. [Sandia National Labs., Albuquerque, NM (United States)

    1993-08-01

    We present a theory of dynamic fragmentation of brittle materials based on thermodynamic arguments. We recover the expressions for average fragment size and number as originally derived by Grady. We extend the previous work by obtaining descriptions of fragment size distribution and compressibility change due to the fragmentation process. The size distribution is assumed to be proportional to the spectral power of the strain history and a sample distribution is presented for a fragmentation process corresponding to a constant rate strain history. The description of compressibility change should be useful in computational studies of fragmentation. These results should provide insight into the process of fragmentation of brittle materials from hypervelocity impact.

  10. Real-time Tracking of DNA Fragment Separation by Smartphone.

    Science.gov (United States)

    Tao, Chunxian; Yang, Bo; Li, Zhenqing; Zhang, Dawei; Yamaguchi, Yoshinori

    2017-06-01

    Slab gel electrophoresis (SGE) is the most common method for the separation of DNA fragments; thus, it is broadly applied to the field of biology and others. However, the traditional SGE protocol is quite tedious, and the experiment takes a long time. Moreover, the chemical consumption in SGE experiments is very high. This work proposes a simple method for the separation of DNA fragments based on an SGE chip. The chip is made by an engraving machine. Two plastic sheets are used for the excitation and emission wavelengths of the optical signal. The fluorescence signal of the DNA bands is collected by smartphone. To validate this method, 50, 100, and 1,000 bp DNA ladders were separated. The results demonstrate that a DNA ladder smaller than 5,000 bp can be resolved within 12 min and with high resolution when using this method, indicating that it is an ideal substitute for the traditional SGE method.

  11. Dependence of Fission-Fragment Properties On Excitation Energy For Neutron-Rich Actinides

    Directory of Open Access Journals (Sweden)

    Ramos D.

    2016-01-01

    Isotopic fission yields of 250Cf, 244Cm, 240Pu, 239Np and 238U are presented in this work. With this information, the average number of neutrons as a function of the atomic number of the fragments is calculated, which reflects the impact of nuclear structure around Z=50, N=80 on the production of fission fragments. The characteristics of the Super Long, Standard I, Standard II, and Standard III fission channels were extracted from fits of the fragment yields for different ranges of excitation energy. The position and contribution of the fission channels as function of excitation energy are presented.

  12. Fluorescent Lamp Replacement Study

    Science.gov (United States)

    2017-07-01

    C -1 D FLUORESCENT LAMP SPECIFICATION SHEETS . . . . . . . . . . . . . . . . . . . . . . . . . . D -1 E LED WAVES’ LED ...friendly products, advances in efficiency, and lower production costs for lamps . The conversion of fluorescent bulbs to LED technology has many benefits...repeatedly turned on and off. (5) LEDs can be used in existing fluorescent lighting fixtures using LED retrofit kits or replacement lamps . (6

  13. Nuclear fragmentation and DNA degradation during programmed cell death in petals of morning glory (Ipomoea nil)

    NARCIS (Netherlands)

    Yamada, T.; Takatsu, Y.; Kasumi, K.; Ichimura, K.; Doorn, van W.G.

    2006-01-01

    We studied DNA degradation and nuclear fragmentation during programmed cell death (PCD) in petals of Ipomoea nil (L.) Roth flowers. The DNA degradation, as observed on agarose gels, showed a large increase. Using DAPI, which stains DNA, and flow cytometry for DAPI fluorescence, we found that the

  14. AN IMAGE-ANALYSIS TECHNIQUE FOR DETECTION OF RADIATION-INDUCED DNA FRAGMENTATION AFTER CHEF ELECTROPHORESIS

    NARCIS (Netherlands)

    ROSEMANN, M; KANON, B; KONINGS, AWT; KAMPINGA, HH

    CHEF-electrophoresis was used as a technique to detect radiation-induced DNA breakage with special emphasis to biological relevant X-ray doses (0-10 Gy). Fluorescence detection of DNA-fragments using a sensitive image analysis system was directly compared with conventional scintillation counting of

  15. Doping of Green Fluorescent Protein into Superfluid Helium Droplets: Size and Velocity of Doped Droplets.

    Science.gov (United States)

    Alghamdi, Maha; Zhang, Jie; Oswalt, Andrew; Porter, Joseph J; Mehl, Ryan A; Kong, Wei

    2017-09-14

    We report doping of green fluorescent protein from an electrospray ionization (ESI) source into superfluid helium droplets. From analyses of the time profiles of the doped droplets, we identify two distinct groups of droplets. The faster group has a smaller average size, on the order of 10(6) helium atoms/droplet, and the slower group is much larger, by at least an order of magnitude. The relative populations of these two groups depend on the temperature of the droplet source: from 11 to 5 K, the signal intensity of the slower droplet group gradually increases, from near the detection limit to comparable to that of the faster group. We postulate that the smaller droplets are formed via condensation of gaseous helium upon expansion from the pulsed valve, while the larger droplets develop from fragmentation of ejected liquid helium. Our results on the size and velocity of the condensation peak at higher source temperatures (>7 K) agree with previous reports, but those at lower temperatures (<7 K) seem to be off. We attribute this discrepancy to the masking effect of the exceedingly large droplets from the fragmentation peak in previous measurements of droplet sizes. Within the temperature range of our investigation, although the expansion condition changes from subcritical to supercritical, there is no abrupt change in either the velocity distribution or the size distribution of the condensation peak, and the most salient effect is in the increasing intensity of the fragmentation peak. The absolute doping efficiency, as expressed by the ratio of ion-doped droplets over the total number of ions from the ESI source, is on the order of 10(-4), while only hundreds of doped ions have been detected. Further improvements in the ESI source are key to extending the technology for future experiments. On the other hand, the separation of the two groups of droplets in velocity is beneficial for size selection of only the smaller droplets for future experiments of electron

  16. Simultaneous speciation analysis of Sb(III), Sb(V) and (CH3)3SbCl2 by high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry detection (HPLC-HG-AFS): application to antimony speciation in sea water.

    Science.gov (United States)

    De Gregori, Ida; Quiroz, Waldo; Pinochet, Hugo; Pannier, Florence; Potin-Gautier, Martine

    2005-10-14

    This paper presents an improvement for the simultaneous separation of Sb(V), Sb(III) and (CH3)3SbCl2 species by high performance liquid chromatography (HPLC) and its detection by hydride generation-atomic fluorescence spectrometry (HG-AFS). The separation was performed on an anion exchange column PRP-X100 using a gradient elution program between EDTA/KHP (potasium hydrogen phtalate) as first mobile phase and phosphate solutions solution as the second one. The chromatographic separation and the HG-AFS parameters were optimized by experimental design. The best results were obtained by using an elution program with 20 mmol l(-1) EDTA + 2 mmol(-01) KHP solution at pH 4.5, during 1.15 min, then change to 50 mmol l(-1) (NH4)2HPO4 solution at pH 8.3, switching back after 4.0 min to the first mobile phase, until 5 min, with a constant flow rate of 1.5 ml min(-1). Retention time of Sb(V), Sb(III) and trimethylantimony species were 1.22, 2.31 and 3.45 min and the detection limits were 0.13; 0.07 and 0.13 microg l(-1), respectively. Studies on the stability of this antimony species in sea water samples on the function of the elapsed time of storage in refrigerator at 4 degrees C was performed employing the optimized method. Results revealed that Sb(III) is easily oxidized within some hours to Sb(V) in sea water stored at 4 degrees C. However, when the sea water was immediately mixed with EDTA no oxidation of Sb(III) was observed up to 1 week of storage. The proposed methodology was then applied to the antimony speciation in sea water samples.

  17. Population pressure and farm fragmentation:

    African Journals Online (AJOL)

    user

    Small farmers play a dominant role in rural area in Rwanda according to many researchers. These farmers have some particular characteristics: most of them have tiny farms, while purchasing and borrowing of land are frequent. In addition, the size of farms is not only very small but farms are further fragmented into ...

  18. Fragmentation of stretched liquid ligaments

    NARCIS (Netherlands)

    Marmottant, P.G.M.; Villermaux, Emmanuel

    2004-01-01

    The dynamics and fragmentation of stretched liquid ligaments is investigated. The ligaments are produced by the withdrawal of a tube initially dipping at a free surface. Time resolved high speed motion experiments reveal two different elongation behaviors, depending on the nondimensional number t,

  19. Fragmented nature: consequences for biodiversity

    NARCIS (Netherlands)

    Olff, H.; Ritchie, M.E.

    2002-01-01

    We discuss how fragmentation of resources and habitat operate differently on species diversity across spatial scales, ranging from positive effects on local species coexistence to negative effect on intermediate spatial scales, to again positive effects on large spatial and temporal scales. Species

  20. Fragmented nature : consequences for biodiversity

    NARCIS (Netherlands)

    Olff, Han; Ritchie, Mark E.

    2002-01-01

    We discuss how fragmentation of resources and habitat operate differently on species diversity across spatial scales, ranging from positive effects on local species coexistence to negative effect on intermediate spatial scales, to again positive effects on large spatial and temporal scales. Species

  1. A new assay based on terminal restriction fragment length polymorphism of homocitrate synthase gene fragments for Candida species identification.

    Science.gov (United States)

    Szemiako, Kasjan; Śledzińska, Anna; Krawczyk, Beata

    2017-08-01

    Candida sp. have been responsible for an increasing number of infections, especially in patients with immunodeficiency. Species-specific differentiation of Candida sp. is difficult in routine diagnosis. This identification can have a highly significant association in therapy and prophylaxis. This work has shown a new application of the terminal restriction fragment length polymorphism (t-RFLP) method in the molecular identification of six species of Candida, which are the most common causes of fungal infections. Specific for fungi homocitrate synthase gene was chosen as a molecular target for amplification. The use of three restriction enzymes, DraI, RsaI, and BglII, for amplicon digestion can generate species-specific fluorescence labeled DNA fragment profiles, which can be used to determine the diagnostic algorithm. The designed method can be a cost-efficient high-throughput molecular technique for the identification of six clinically important Candida species.

  2. A desirability function-based scoring scheme for selecting fragment-like class A aminergic GPCR ligands

    Science.gov (United States)

    Kelemen, Ádám A.; Ferenczy, György G.; Keserű, György M.

    2015-01-01

    A physicochemical property-based desirability scoring scheme for fragment-based drug discovery was developed for class A aminergic GPCR targeted fragment libraries. Physicochemical property distributions of known aminergic GPCR-active fragments from the ChEMBL database were examined and used for a desirability function-based score. Property-distributions such as log D (at pH 7.4), PSA, pKa (strongest basic center), number of nitrogen atoms, number of oxygen atoms, and the number of rotatable bonds were combined into a desirability score (FrAGS). The validation of the scoring scheme was carried out using both public and proprietary experimental screening data. The scoring scheme is suitable for the design of aminergic GPCR targeted fragment libraries and might be useful for preprocessing fragments before structure based virtual or wet screening.

  3. Atomic vapor density monitor

    Energy Technology Data Exchange (ETDEWEB)

    Sewall, N.; Harris, W.; Beeler, R.; Wooldridge, J.; Chen, H.L.

    1986-09-01

    This report presents information on the Atomic Vapor Density Monitor (AVDM) system that measures the density of a vapor by measuring the absorption of light from a swept-wavelength laser that passes through an atomic vapor stream.

  4. Fast metastable hydrogen atoms from H2 molecules: twin atoms

    Directory of Open Access Journals (Sweden)

    Trimèche A.

    2015-01-01

    Full Text Available It is a difficult task to obtain “twin atoms”, i.e. pairs of massive particles such that one can perform experiments in the same fashion that is routinely done with “twin photons”. One possible route to obtain such pairs is by dissociating homonuclear diatomic molecules. We address this possibility by investigating the production of metastable H(2s atoms coming from the dissociation of cold H2 molecules produced in a Campargue nozzle beam crossing an electron beam from a high intensity pulsed electron gun. Dissociation by electron impact was chosen to avoid limitations of target molecular excited states due to selection rules. Detectors placed several centimeters away from the collision center, and aligned with respect to possible common molecular dissociation channel, analyze the neutral fragments as a function of their time-of-flight (TOF through Lyman-α detection. Evidence for the first time observed coincidence of pairs of H(2s atoms obtained this way is presented.

  5. The VERDI fission fragment spectrometer

    Directory of Open Access Journals (Sweden)

    Frégeau M.O.

    2013-12-01

    Full Text Available The VERDI time-of-flight spectrometer is dedicated to measurements of fission product yields and of prompt neutron emission data. Pre-neutron fission-fragment masses will be determined by the double time-of-flight (TOF technique. For this purpose an excellent time resolution is required. The time of flight of the fragments will be measured by electrostatic mirrors located near the target and the time signal coming from silicon detectors located at 50 cm on both sides of the target. This configuration, where the stop detector will provide us simultaneously with the kinetic energy of the fragment and timing information, significantly limits energy straggling in comparison to legacy experimental setup where a thin foil was usually used as a stop detector. In order to improve timing resolution, neutron transmutation doped silicon will be used. The high resistivity homogeneity of this material should significantly improve resolution in comparison to standard silicon detectors. Post-neutron fission fragment masses are obtained form the time-of-flight and the energy signal in the silicon detector. As an intermediary step a diamond detector will also be used as start detector located very close to the target. Previous tests have shown that poly-crystalline chemical vapour deposition (pCVD diamonds provides a coincidence time resolution of 150 ps not allowing complete separation between very low-energy fission fragments, alpha particles and noise. New results from using artificial single-crystal diamonds (sCVD show similar time resolution as from pCVD diamonds but also sufficiently good energy resolution.

  6. Dynamics Resonances in Atomic States of Astrophysical Relevance

    CERN Document Server

    Arefieff, K N; Bezuglov, N N; Dimitrijevic, M S; Klyucharev, A N; Mihajlov, A A; Sreckovic, V A

    2016-01-01

    Ionized geocosmic media parameters in a thermal and a subthermal range of energy have a number of unique features. The photoresonance plasma that is formed by optical excitation of the lowest excited (resonance) atomic states is one example of conversion of radiation energy into electrical one. Since spontaneous fluorescence of excited atoms is probabilistic, the description of the radiating quantized system evolution along with photons energy transfer in a cold atoms medium, should include elements of stochastic dynamics. Finally, the chaotic dynamics of a weakly bound Rydberg electron over a grid of the energy levels diagram of a quasi-molecular Rydberg complex provides an excitation migration of the electron forward to the ionization continuum. This work aims at discussing the specific features of the dynamic resonances formalism in the description of processes involving Rydberg states of an excited atom, including features in the fluorescence spectrum partially caused by the quantum defect control due to ...

  7. Atomic Spectra Database (ASD)

    Science.gov (United States)

    SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

  8. Playing Pinball with Atoms

    NARCIS (Netherlands)

    Saedi, A.; van Houselt, Arie; van Gastel, Raoul; Poelsema, Bene; Zandvliet, Henricus J.W.

    2009-01-01

    We demonstrate the feasibility of controlling an atomic scale mechanical device by an external electrical signal. On a germanium substrate, a switching motion of pairs of atoms is induced by electrons that are directly injected into the atoms with a scanning tunneling microscope tip. By precisely

  9. Fragmentation

    Science.gov (United States)

    K.H. Riitters

    2009-01-01

    Effective resource management takes into account the administrative and biophysical settings within which natural resources occur. A setting may be described in many ways; for example, by forest land ownership, by reserved and roadless designation, or by the distribution of human populations in relation to forest (chapter 3). The physical arrangement of forest in a...

  10. Isotopic scaling and the symmetry energy in spectator fragmentation.

    Science.gov (United States)

    Le Fèvre, A; Auger, G; Begemann-Blaich, M L; Bellaize, N; Bittiger, R; Bocage, F; Borderie, B; Bougault, R; Bouriquet, B; Charvet, J L; Chbihi, A; Dayras, R; Durand, D; Frankland, J D; Galichet, E; Gourio, D; Guinet, D; Hudan, S; Immé, G; Lautesse, P; Lavaud, F; Legrain, R; Lopez, O; Łukasik, J; Lynen, U; Müller, W F J; Nalpas, L; Orth, H; Plagnol, E; Raciti, G; Rosato, E; Saija, A; Schwarz, C; Seidel, W; Sfienti, C; Tamain, B; Trautmann, W; Trzciński, A; Turzó, K; Vient, E; Vigilante, M; Volant, C; Zwiegliński, B; Botvina, A S

    2005-04-29

    Isotopic effects in the fragmentation of excited target residues following collisions of 12C on (112,124)Sn at incident energies of 300 and 600 MeV per nucleon were studied with the INDRA 4pi detector. The measured yield ratios for light particles and fragments with atomic number Z < or = 5 obey the exponential law of isotopic scaling. The deduced scaling parameters decrease strongly with increasing centrality to values smaller than 50% of those obtained for the peripheral event groups. Symmetry-term coefficients, deduced from these data within the statistical description of isotopic scaling, are near gamma = 25 MeV for peripheral and gamma < 15 MeV for central collisions.

  11. Atomization characteristics of a prefilming airblast atomizer

    Science.gov (United States)

    Hayashi, Shigeru; Koito, Atsushi; Hishiki, Manabu

    1992-01-01

    The size distribution of water test sprays generated by a prefilming airblast atomizer used for aeroengines was measured in swirling and non-swirling flows with the well established laser scattering particle sizing technique. Atomizing air velocity (or pressure difference) was varied in a range wider than the conditions of actual engines. The Sauter Mean Diameter (SMD) decreased at approximately a 1.5 power of the atomizing air velocity, being a higher velocity index than the previously reported values of 1 to 1.2. It was unexpectedly found that the effect of the liquid/air flow ratio was small. Since swirling flow increased the SMD at lower air velocities yet decreased it at higher ones, it is suggested that the reverse flow near the nozzle pintle adversely affects atomization.

  12. Field-dependent atomic relaxation in a squeezed vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, S S [Department of Mathematics, College of Science, University of Bahrain, PO Box 32038 (Bahrain); Jarad, T M [UMIST, Department of Mathematics, PO Box 88, Manchester M60 1QD (United Kingdom); Puri, R R [Bhabha Atomic Research Centre, Theoretical Physics Division, Bombay 400085 (India); Bullough, R K [UMIST, Department of Mathematics, PO Box 88, Manchester M60 1QD (United Kingdom)

    2005-11-01

    The relaxation process of a single two-level atom driven by an intense resonant coherent field is studied in the presence of a broadband squeezed vacuum field. Generalized forms for the self-field operator and the field-dependent damping coefficients are derived. In the steady state, positive atomic inversion ({approx}5%) is shown for some range of the phase of the squeezed vacuum field. The squeezing-induced enhanced and asymmetric coherence (i.e. non-zero dispersive atomic polarization) induces profound asymmetry in the side-bands of the Mollow fluorescent spectrum and the absorptive-dispersive spectra near the Rabi side-band frequencies. The case of two and three cooperative atoms, instead of a single atom, shows (i) positive atomic inversion in the steady state for larger interval of the squeeze phase parameter and more enhanced extrema for the atomic polarization components and (ii) the extra side peaks in the fluorescent spectrum become asymmetric and of dispersive-like profile. Dressed-state analysis in the single-atom case with the field-dependent decay process in the presence of the squeezed vacuum field is presented and shows that the inequality of the (field-dependent) decay rates of the dressed states leads to more positive inversion in the dressed states as compared with the normal vacuum case.

  13. Field-dependent atomic relaxation in a squeezed vacuum

    Science.gov (United States)

    Hassan, S. S.; Jarad, T. M.; Puri, R. R.; Bullough, R. K.

    2005-11-01

    The relaxation process of a single two-level atom driven by an intense resonant coherent field is studied in the presence of a broadband squeezed vacuum field. Generalized forms for the self-field operator and the field-dependent damping coefficients are derived. In the steady state, positive atomic inversion (~5%) is shown for some range of the phase of the squeezed vacuum field. The squeezing-induced enhanced and asymmetric coherence (i.e. non-zero dispersive atomic polarization) induces profound asymmetry in the side-bands of the Mollow fluorescent spectrum and the absorptive-dispersive spectra near the Rabi side-band frequencies. The case of two and three cooperative atoms, instead of a single atom, shows (i) positive atomic inversion in the steady state for larger interval of the squeeze phase parameter and more enhanced extrema for the atomic polarization components and (ii) the extra side peaks in the fluorescent spectrum become asymmetric and of dispersive-like profile. Dressed-state analysis in the single-atom case with the field-dependent decay process in the presence of the squeezed vacuum field is presented and shows that the inequality of the (field-dependent) decay rates of the dressed states leads to more positive inversion in the dressed states as compared with the normal vacuum case.

  14. Single atom electrochemical and atomic analytics

    Science.gov (United States)

    Vasudevan, Rama

    In the past decade, advances in electron and scanning-probe based microscopies have led to a wealth of imaging and spectroscopic data with atomic resolution, yielding substantial insight into local physics and chemistry in a diverse range of systems such as oxide catalysts, multiferroics, manganites, and 2D materials. However, typical analysis of atomically resolved images is limited, despite the fact that image intensities and distortions of the atoms from their idealized positions contain unique information on the physical and chemical properties inherent to the system. Here, we present approaches to data mine atomically resolved images in oxides, specifically in the hole-doped manganite La5/8Ca3/8MnO3, on epitaxial films studied by in-situ scanning tunnelling microscopy (STM). Through application of bias to the STM tip, atomic-scale electrochemistry is demonstrated on the manganite surface. STM images are then further analyzed through a suite of algorithms including 2D autocorrelations, sliding window Fourier transforms, and others, and can be combined with basic thermodynamic modelling to reveal relevant physical and chemical descriptors including segregation energies, existence and strength of atomic-scale diffusion barriers, surface energies and sub-surface chemical species identification. These approaches promise to provide tremendous insights from atomically resolved functional imaging, can provide relevant thermodynamic parameters, and auger well for use with first-principles calculations to yield quantitative atomic-level chemical identification and structure-property relations. This research was sponsored by the Division of Materials Sciences and Engineering, BES, DOE. Research was conducted at the Center for Nanophase Materials Sciences, which also provided support and is a DOE Office of Science User Facility.

  15. Multilevel Atomic Coherent States and Atomic Holomorphic Representation

    Science.gov (United States)

    Cao, Chang-Qi; Haake, Fritz

    1996-01-01

    The notion of atomic coherent states is extended to the case of multilevel atom collective. Based on atomic coherent states, a holomorphic representation for atom collective states and operators is defined. An example is given to illustrate its application.

  16. Fragment separator momentum compression schemes

    Energy Technology Data Exchange (ETDEWEB)

    Bandura, Laura, E-mail: bandura@anl.gov [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); National Superconducting Cyclotron Lab, Michigan State University, 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Erdelyi, Bela [Argonne National Laboratory, Argonne, IL 60439 (United States); Northern Illinois University, DeKalb, IL 60115 (United States); Hausmann, Marc [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Kubo, Toshiyuki [RIKEN Nishina Center, RIKEN, Wako (Japan); Nolen, Jerry [Argonne National Laboratory, Argonne, IL 60439 (United States); Portillo, Mauricio [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Sherrill, Bradley M. [National Superconducting Cyclotron Lab, Michigan State University, 1 Cyclotron, East Lansing, MI 48824-1321 (United States)

    2011-07-21

    We present a scheme to use a fragment separator and profiled energy degraders to transfer longitudinal phase space into transverse phase space while maintaining achromatic beam transport. The first order beam optics theory of the method is presented and the consequent enlargement of the transverse phase space is discussed. An interesting consequence of the technique is that the first order mass resolving power of the system is determined by the first dispersive section up to the energy degrader, independent of whether or not momentum compression is used. The fragment separator at the Facility for Rare Isotope Beams is a specific application of this technique and is described along with simulations by the code COSY INFINITY.

  17. Fragment separator momentum compression schemes.

    Energy Technology Data Exchange (ETDEWEB)

    Bandura, L.; Erdelyi, B.; Hausmann, M.; Kubo, T.; Nolen, J.; Portillo, M.; Sherrill, B.M. (Physics); (MSU); (Northern Illinois Univ.); (RIKEN)

    2011-07-21

    We present a scheme to use a fragment separator and profiled energy degraders to transfer longitudinal phase space into transverse phase space while maintaining achromatic beam transport. The first order beam optics theory of the method is presented and the consequent enlargement of the transverse phase space is discussed. An interesting consequence of the technique is that the first order mass resolving power of the system is determined by the first dispersive section up to the energy degrader, independent of whether or not momentum compression is used. The fragment separator at the Facility for Rare Isotope Beams is a specific application of this technique and is described along with simulations by the code COSY INFINITY.

  18. Fragment separator momentum compression schemes

    Science.gov (United States)

    Bandura, Laura; Erdelyi, Bela; Hausmann, Marc; Kubo, Toshiyuki; Nolen, Jerry; Portillo, Mauricio; Sherrill, Bradley M.

    2011-07-01

    We present a scheme to use a fragment separator and profiled energy degraders to transfer longitudinal phase space into transverse phase space while maintaining achromatic beam transport. The first order beam optics theory of the method is presented and the consequent enlargement of the transverse phase space is discussed. An interesting consequence of the technique is that the first order mass resolving power of the system is determined by the first dispersive section up to the energy degrader, independent of whether or not momentum compression is used. The fragment separator at the Facility for Rare Isotope Beams is a specific application of this technique and is described along with simulations by the code COSY INFINITY.

  19. Fragmentering og korridorer i landskabet

    DEFF Research Database (Denmark)

    Hammershøj, M.; Madsen, A. B.

    , at fragmentering af habitater resulterer i en reduktion og isolering af mange plante- og dyrepopulationer. Det er desuden vist, at korridorer har en funktion som habitater, hvilket er medvirkende til, at et område med korridorer kan huse flere arter og individer end et tilsvarende område uden korridorer. Der......Rapporten indeholder en litteraturudredning, der er baseret på en bearbejdning af den tilgængelige nationale og internationale litteratur omhandlende fragmentering og korridorer på det botaniske og zoologiske område. I alt 1.063 titler ligger til grund for udredningen. Udredningen har vist...... mangler dog entydige beviser for, at korridorer kan være af afgørende betydning for rekolonisering af habitater, i hvilke en given art er forsvundet. Afslutningsvis gives en liste med forskningsbehov samt en række anbefalinger....

  20. Fragmentation in the biopharmaceutical industry.

    Science.gov (United States)

    Goldsmith, Andrew D; Varela, Francisco E

    2017-02-01

    The large number of biopharmaceutical mergers and acquisitions (M&A) that occurred over the past decade has generated questions about whether the industry is consolidating around too-few players, negatively impacting both the number of medicines developed and overall innovation. However, closer examination of the level of biopharmaceutical consolidation by prescription sales shows that the industry was more fragmented in 2015 than in 2003. The trend towards increasing fragmentation is also observed across noncommercial and independent metrics over the same time period. The number and size of M&A deals has masked an active and competitive marketplace in which market growth and the number of companies entering the market exceeded the apparent reduction in the number of players caused by acquisitions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Transverse Velocity Scaling in Au+Au Fragmentation

    OpenAIRE

    Lukasik, J.; Hudan, S.; Lavaud, F.; Turzo, K.; Auger, G.; Bacri, Ch.O.; Begemann-Blaich, M.L.; Bellaize, N.; Bittiger, R.; Bocage, F.; Borderie, B.; Buchet, P.; R. Bougault(LPCC); Bouriquet, B.; Charvet, J. L.

    2002-01-01

    Invariant transverse-velocity spectra of intermediate-mass fragments were measured with the 4-pi multi-detector system INDRA for collisions of Au on Au at incident energies between 40 and 150 MeV per nucleon. Their scaling properties as a function of incident energy and atomic number Z are used to distinguish and characterize the emissions in (i) peripheral collisions at the projectile and target rapidities, and in (ii) central and (iii) peripheral collisions near mid-rapidity. The importance...

  2. Fast Nondestructive Parallel Readout of Neutral Atom Registers in Optical Potentials

    Science.gov (United States)

    Martinez-Dorantes, M.; Alt, W.; Gallego, J.; Ghosh, S.; Ratschbacher, L.; Völzke, Y.; Meschede, D.

    2017-11-01

    We demonstrate the parallel and nondestructive readout of the hyperfine state for optically trapped 87Rb atoms. The scheme is based on state-selective fluorescence imaging and achieves detection fidelities >98 % within 10 ms, while keeping 99% of the atoms trapped. For the readout of dense arrays of neutral atoms in optical lattices, where the fluorescence images of neighboring atoms overlap, we apply a novel image analysis technique using Bayesian inference to determine the internal state of multiple atoms. Our method is scalable to large neutral atom registers relevant for future quantum information processing tasks requiring fast and nondestructive readout and can also be used for the simultaneous readout of quantum information stored in internal qubit states and in the atoms' positions.

  3. Carcinogenesis of Depleted Uranium Fragments.

    Science.gov (United States)

    1996-02-01

    29 of 54 Chinese hamsters injected intravenously with a relatively high dose of Thorotrast (> 0.4 Bq/g) developed fibrosarcomas from perivascular...leakage of some injections (Guilmette et al., 1989). Plutonium fragments have been injected into the footpads of dogs to simulate the plutonium...extensively studied in animals, particularly in rats (Haley, 1982; Haley et al., 1982; Diamond et al., 1987; Morrow et al., 1982) and dogs (Morrow et al

  4. Modeling of Fragmentation of Asteroids

    Science.gov (United States)

    Agrawal, Parul; Prabhu, Dinesh K.; Carlozzi, Alexander; Hart, Kenneth; Bryson, Katie; Sears, Derek

    2015-01-01

    The objective of this study is to understand fragmentation and fracture of a given asteroid and mechanisms of break-up. The focus of the present work is to develop modeling techniques for stony asteroids in 10m-100m range to answer two questions: 1) What is the role of material makeup of an asteroid in the stress distribution? 2)How is stress distribution altered in the presence of pre-existing defects?

  5. Structure, fragmentation and fracture functions

    CERN Document Server

    Canal-Garcia, C A

    2000-01-01

    We address the partonic description of the proton, the photon and the "color singlet, " as seen in inclusive and semi-inclusive DIS, in e /sup +/e/sup $/collisions, and in diffractive processes, respectively. Their formal treatment using structure, fragmentation, and fracture functions is outlined giving an insight into the perturbative QCD framework for these functions. Examples and comparisons with experimental data from LEP, HERA, and Tevatron are also covered. (52 refs).

  6. Fibril fragmentation enhances amyloid cytotoxicity.

    Science.gov (United States)

    Xue, Wei-Feng; Hellewell, Andrew L; Gosal, Walraj S; Homans, Steve W; Hewitt, Eric W; Radford, Sheena E

    2009-12-04

    Fibrils associated with amyloid disease are molecular assemblies of key biological importance, yet how cells respond to the presence of amyloid remains unclear. Cellular responses may not only depend on the chemical composition or molecular properties of the amyloid fibrils, but their physical attributes such as length, width, or surface area may also play important roles. Here, we report a systematic investigation of the effect of fragmentation on the structural and biological properties of amyloid fibrils. In addition to the expected relationship between fragmentation and the ability to seed, we show a striking finding that fibril length correlates with the ability to disrupt membranes and to reduce cell viability. Thus, despite otherwise unchanged molecular architecture, shorter fibrillar samples show enhanced cytotoxic potential than their longer counterparts. The results highlight the importance of fibril length in amyloid disease, with fragmentation not only providing a mechanism by which fibril load can be rapidly increased but also creating fibrillar species of different dimensions that can endow new or enhanced biological properties such as amyloid cytotoxicity.

  7. Residual Fragments after Percutaneous Nephrolithotomy

    Directory of Open Access Journals (Sweden)

    Kaan Özdedeli

    2012-09-01

    Full Text Available Clinically insignificant residual fragments (CIRFs are described as asymptomatic, noninfectious and nonobstructive stone fragments (≤4 mm remaining in the urinary system after the last session of any intervention (ESWL, URS or PCNL for urinary stones. Their insignificance is questionable since CIRFs could eventually become significant, as their presence may result in recurrent stone growth and they may cause pain and infection due to urinary obstruction. They may become the source of persistent infections and a significant portion of the patients will have a stone-related event, requiring auxilliary interventions. CT seems to be the ultimate choice of assessment. Although there is no concensus about the timing, recent data suggests that it may be performed one month after the procedure. However, imaging can be done in the immediate postoperative period, if there are no tubes blurring the assessment. There is some evidence indicating that selective medical therapy may have an impact on decreasing stone formation rates. Retrograde intrarenal surgery, with its minimally invasive nature, seems to be the best way to deal with residual fragments.

  8. Ionization and fragmentation modes of nucleobases after collisions with multiply charged ions

    NARCIS (Netherlands)

    Hoekstra, R.; Morgenstern, R.; Schlathoelter, T.

    2004-01-01

    We studied multiply charged ion (MCI) induced ionization, excitation and fragmentation of the nucleobases uracil and thymine. Ions of different charge state at velocities between 0.2 and 0.4 atomic units were used as projectiles. By means of time-of-flight spectrometry of the collision products in a

  9. Ion induced excitation and fragmentation of fullerenes and small organic molecules

    NARCIS (Netherlands)

    Schlathölter, Thomas; Hadjar, O; de Vries, J.; Hoekstra, R; Morgenstern, R; Burgdorfer, J; Cohen, JS; Datz, S; Vane, CR

    2001-01-01

    The interaction of multiply charged ions with fullerenes involves processes such as ionization, evaporation, fragmentation and electron emission. The relative importance of these deexciation channels depends on the projectile parameters charge state q, velocity v and atomic number Z. We give a brief

  10. Observation of the Hydrogen Migration in the Cation-Induced Fragmentation of the Pyridine Molecules.

    Science.gov (United States)

    Wasowicz, Tomasz J; Pranszke, Bogusław

    2016-02-25

    The ability to selectively control chemical reactions related to biology, combustion, and catalysis has recently attracted much attention. In particular, the hydrogen atom relocation may be used to manipulate bond-breaking and new bond-forming processes and may hold promise for far-reaching applications. Thus, the hydrogen atom migration preceding fragmentation of the gas-phase pyridine molecules by the H(+), H2(+), He(+), He(2+), and O(+) impact has been studied experimentally in the energy range of 5-2000 eV using collision-induced luminescence spectroscopy. Formation of the excited NH(A(3)Π) radicals was observed among the atomic and diatomic fragments. The structure of the pyridine molecule is lacking of the NH group, therefore observation of its A(3)Π → X(3)Σ(-) emission bands is an evidence of the hydrogen atom relocation prior to the cation-induced fragmentation. The NH(A(3)Π) emission yields indicate that formation of the NH radicals depends on the type of selected projectile and can be controlled by tuning its velocity. The plausible collisional mechanisms as well as fragmentation channels for NH formation in pyridine are discussed.

  11. A Method for Predicting Fragmentation Characteristics of Natural and Performed Explosive Fragmentation Munitions

    National Research Council Canada - National Science Library

    Gold, Vladimir

    2001-01-01

    New methodology for simulating performance of explosive fragmentation munitions presented in this work integrates three-dimensional axisymmetric hydrocode analyses with analytical fragmentation modeling...

  12. Perturbation calculations of the interaction energies between non-bonded hydrogen atoms - Part 2

    NARCIS (Netherlands)

    Laidlaw, W.G.; Lekkerkerker, H.N.W.; Wieser, H.

    1971-01-01

    Calculations of the interaction energy between non-bonded hydrogen atoms in the fragments A—H---H'—A' for selected displacements of the hydrogen atoms enable one to evaluate corrections to the force field due to the non-bonded interactions and to discuss the changes in the stretching vibration

  13. Fluorescence Live Cell Imaging

    OpenAIRE

    Ettinger, Andreas; Wittmann, Torsten

    2014-01-01

    Fluorescence microscopy of live cells has become an integral part of modern cell biology. Fluorescent protein (FP) tags, live cell dyes, and other methods to fluorescently label proteins of interest provide a range of tools to investigate virtually any cellular process under the microscope. The two main experimental challenges in collecting meaningful live cell microscopy data are to minimize photodamage while retaining a useful signal-to-noise ratio and to provide a suitable environment for ...

  14. Fragmentation of small carbon clusters, a review

    Energy Technology Data Exchange (ETDEWEB)

    Beroff, K. [Laboratoire des Collisions Atomiques et Moleculaires, CNRS and Universite Paris-Sud, batiment 351, 91405 Orsay Cedex (France)], E-mail: karine.beroff@u-psud.fr; Chabot, M. [Institut de Physique Nucleaire, CNRS-IN2P3 and Universite Paris-Sud, 91405 Orsay Cedex (France); Mezdari, F. [Laboratoire des Collisions Atomiques et Moleculaires, CNRS and Universite Paris-Sud, batiment 351, 91405 Orsay Cedex (France); Martinet, G.; Tuna, T. [Institut de Physique Nucleaire, CNRS-IN2P3 and Universite Paris-Sud, 91405 Orsay Cedex (France); Desesquelles, P. [Centre de Spectrometrie Nucleaire et Spectrometrie de Masse, Universite Paris-Sud and CNRS-IN2P3, batiment 104, 91405 Orsay Cedex (France); LePadellec, A. [Institut de Recherche sur les Systemes Atomiques et Moleculaires Complexes, Universite Paul Sabatier and CNRS, batiment 3R1B4, 31062 Toulouse Cedex 9 (France); Barat, M. [Laboratoire des Collisions Atomiques et Moleculaires, CNRS and Universite Paris-Sud, batiment 351, 91405 Orsay Cedex (France)

    2009-03-15

    An overview of the works devoted to fragmentation of small carbon clusters is given in a first part. Fragmentation of swift neutral and (multi) charged carbon clusters studied with the AGAT spectrometer is presented and discussed in a second part.

  15. Fragmentation of small carbon clusters, a review

    OpenAIRE

    Béroff, K.; Chabot, M.; Mezdari, F.; Martinet, G.; Tuna, T.; Désesquelles, P.; Le Padellec, Arnaud; Barat, M.

    2008-01-01

    An overview of the works devoted to fragmentation of small carbon clusters is given in a first part. Fragmentation of swift neutral and (multi) charged carbon clusters studied with the AGAT spectrometer is presented and discussed in a second part.

  16. Identification of amplified fragment length polymorphism (AFLP ...

    African Journals Online (AJOL)

    Identification of amplified fragment length polymorphism (AFLP) fragments linked to soybean mosaic virus resistance gene in Glycine soja and conversion to a sequence characterized amplified regions (SCAR) marker for rapid selection.

  17. Long range intermolecular forces in triatomic systems: connecting the atom-diatom and atom-atom-atom representations

    OpenAIRE

    Cvitas, Marko T.; Soldan, Pavel; Hutson, Jeremy M.

    2005-01-01

    The long-range forces that act between three atoms are analysed in both atom-diatom and atom-atom-atom representations. Expressions for atom-diatom dispersion coefficients are obtained in terms of 3-body nonadditive coefficients. The anisotropy of atom-diatom C_6 dispersion coefficients arises primarily from nonadditive triple-dipole and quadruple-dipole forces, while pairwise-additive forces and nonadditive triple-dipole and dipole-dipole-quadrupole forces contribute significantly to atom-di...

  18. Fragment Kinetic Energies and Modes of Fragment Formation

    Science.gov (United States)

    Odeh, T.; Bassini, R.; Begemann-Blaich, M.; Fritz, S.; Gaff-Ejakov, S. J.; Gourio, D.; Groß, C.; Immé, G.; Iori, I.; Kleinevoß, U.; Kunde, G. J.; Kunze, W. D.; Lynen, U.; Maddalena, V.; Mahi, M.; Möhlenkamp, T.; Moroni, A.; Müller, W. F.; Nociforo, C.; Ocker, B.; Petruzzelli, F.; Pochodzalla, J.; Raciti, G.; Riccobene, G.; Romano, F. P.; Saija, A.; Schnittker, M.; Schüttauf, A.; Schwarz, C.; Seidel, W.; Serfling, V.; Sfienti, C.; Trautmann, W.; Trzcinski, A.; Verde, G.; Wörner, A.; Xi, Hongfei; Zwieglinski, B.

    2000-05-01

    Kinetic energies of light fragments ( A<=10) from the decay of target spectators in 197Au+197Au collisions at 1000 MeV per nucleon have been measured with high-resolution telescopes at backward angles. Except for protons and apart from the observed evaporation components, the kinetic-energy spectra exhibit slope temperatures of about 17 MeV, independent of the particle species, but not corresponding to the thermal or chemical degrees of freedom at breakup. It is suggested that these slope temperatures may reflect the intrinsic Fermi motion and thus the bulk density of the spectator system at the instant of becoming unstable.

  19. Multiphoton ionization-fragmentation patterns of tertiary amines

    Science.gov (United States)

    Parker, D. H.; Bernstein, R. B.; Lichtin, D. A.

    1981-09-01

    Multiphoton ionization (MPI)-fragmentation patterns are reported for a series of normal and caged tertiary amines. Ionization is enhanced by two-photon resonance with the 3s and 3p Rydberg states of trimethylamine, triethylamine, and the caged amines quinuclidine and triethylenediamine. Over the wavelength region λ = 400-530 nm, N(CH3)3 ionizes to the parent ion (P) and fragments only by the loss of a H atom to yield the P-H daughter ion; N(C2H5)3 ionizes to its parent ion and fragments by the loss of a methyl to form the P-CH3 ion. The branching ratio of daughter to parent ions is found to be essentially independent of laser intensity but strongly dependent on laser wavelength. The caged amines quinuclidine [N(C2H4)3CH, or ABCO] and triethylenediamine [N(C2H4)3N, or DABCO] fragment extensively over this λ range in a manner dependent on both laser wavelength and intensity. The extent of daughter ion formation in N(CH3)3 and N(C2H5)3 can be understood by consideration of the wavelength regions in which the total available energy from the initial three- or four-photon ionization event exceeds the appearance potential of the given daughter ion. For the caged amines direct observation of this mechanism is masked by fragmentation due to sequential absorption of photons (during the ˜5 ns pulse duration) by the parent and/or daughter ions. The present results show that even for molecules with broad, unstructured UV absorption and MPI spectra such as N(CH3)3 and N(C2H5)3, considerable information on photon-molecule and photon-ion interactions can still be gained by the MPI mass spectrometry technique.

  20. Optimal Economic Landscapes with Habitat Fragmentation Effects

    OpenAIRE

    Lewis, David J.; Wu, JunJie

    2005-01-01

    Habitat fragmentation is widely considered a primary threat to biodiversity. This paper develops a theoretical model of land use to analyze the optimal conservation of landscapes when land quality is spatially heterogeneous and wildlife habitat is fragmented and socially valuable. When agriculture is the primary cause of fragmentation, we show that reforestation efforts should be targeted to the most fragmented landscapes with an aggregate share of forest equal to a threshold, defined by the ...

  1. Condensed matter applied atomic collision physics, v.4

    CERN Document Server

    Datz, Sheldon

    1983-01-01

    Applied Atomic Collision Physics, Volume 4: Condensed Matter deals with the fundamental knowledge of collision processes in condensed media.The book focuses on the range of applications of atomic collisions in condensed matter, extending from effects on biological systems to the characterization and modification of solids. This volume begins with the description of some aspects of the physics involved in the production of ion beams. The radiation effects in biological and chemical systems, ion scattering and atomic diffraction, x-ray fluorescence analysis, and photoelectron and Auger spectrosc

  2. Self-organized criticality in fragmenting

    DEFF Research Database (Denmark)

    Oddershede, L.; Dimon, P.; Bohr, J.

    1993-01-01

    The measured mass distributions of fragments from 26 fractured objects of gypsum, soap, stearic paraffin, and potato show evidence of obeying scaling laws; this suggests the possibility of self-organized criticality in fragmenting. The probability of finding a fragment scales inversely to a power...

  3. Scaling and four-quark fragmentation

    NARCIS (Netherlands)

    Scholten, O.; Bosveld, G. D.

    1991-01-01

    The conditions for a scaling behaviour from the fragmentation process leading to slow protons are discussed. The scaling referred to implies that the fragmentation functions depend on the light-cone momentum fraction only. It is shown that differences in the fragmentation functions for valence- and

  4. Population pressure and farm fragmentation: Challenges facing ...

    African Journals Online (AJOL)

    In addition, the size of farms is not only very small but farms are further fragmented into diminutive size fields due to increasing population pressure. The magnitude of fragmentation has increased overtime. Effects of population pressure and farm fragmentation are studied based on a survey of 200 households from Rusatira ...

  5. Single atom microscopy.

    Science.gov (United States)

    Zhou, Wu; Oxley, Mark P; Lupini, Andrew R; Krivanek, Ondrej L; Pennycook, Stephen J; Idrobo, Juan-Carlos

    2012-12-01

    We show that aberration-corrected scanning transmission electron microscopy operating at low accelerating voltages is able to analyze, simultaneously and with single atom resolution and sensitivity, the local atomic configuration, chemical identities, and optical response at point defect sites in monolayer graphene. Sequential fast-scan annular dark-field (ADF) imaging provides direct visualization of point defect diffusion within the graphene lattice, with all atoms clearly resolved and identified via quantitative image analysis. Summing multiple ADF frames of stationary defects produce images with minimized statistical noise and reduced distortions of atomic positions. Electron energy-loss spectrum imaging of single atoms allows the delocalization of inelastic scattering to be quantified, and full quantum mechanical calculations are able to describe the delocalization effect with good accuracy. These capabilities open new opportunities to probe the defect structure, defect dynamics, and local optical properties in 2D materials with single atom sensitivity.

  6. Solar Spectroscopy: Atomic Processes

    Science.gov (United States)

    Mason, H.; Murdin, P.

    2000-11-01

    A Greek philosopher called DEMOCRITUS (c. 460-370 BC) first introduced the concept of atoms (which means indivisible). His atoms do not precisely correspond to our atoms of today, which are not indivisible, but made up of a nucleus (protons with positive charge and neutrons which have no charge) and orbiting electrons (with negative charge). Indeed, in the solar atmosphere, the temperature is suc...

  7. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1997-01-01

    This series describes selected advances in the area of atomic spectroscopy. It is primarily intended for the reader who has a background in atmoic spectroscopy; suitable to the novice and expert. Although a widely used and accepted method for metal and non-metal analysis in a variety of complex samples, Advances in Atomic Spectroscopy covers a wide range of materials. Each Chapter will completely cover an area of atomic spectroscopy where rapid development has occurred.

  8. Optical Thin Film Thickness Measurement for the Single Atom Microscope

    Science.gov (United States)

    Nelson, Courtney; Frisbie, Dustin; Singh, Jaideep; Spinlab Team

    2017-09-01

    The Single Atom Microscope Project proposes an efficient, selective, and sensitive method to measure the 1022Ne+24 He ->1225 Mg + n reaction. This rare nuclear reaction is a source of neutrons for heavy element development through the slow neutron capture process. This method embeds Magnesium atoms in a solid neon film. The Magnesium atoms exhibit a shifted fluorescence spectrum allowing for the detection of individual fluorescence photons against the excitation light background. Currently, Ytterbium is used in place of Magnesium-25 because it has been more thoroughly studied than Magnesium and we expect it to have a brighter signal. To identify the signal emitted from the Ytterbium atoms, we need to quantify the amount of signal and background per atom in the neon film. We need to know the film thickness to find the number of atoms in the film to determine the amount of light emitted per atom. In preparation for the neon film measurement, I constructed an experiment to advance the understanding of what is required to optically measure a thin film by using a cover glass slide in place of the thin film. This preliminary experiment has determined a measurement method for finding the thickness of a neon thin film on a sapphire substrate. This work is supported by Michigan State University, U.S. National Science Foundation under Grant Number 1654610, and U.S. NSF REU.

  9. Fragmentation in massive star formation.

    Science.gov (United States)

    Beuther, Henrik; Schilke, Peter

    2004-02-20

    Studies of evolved massive stars indicate that they form in a clustered mode. During the earliest evolutionary stages, these regions are embedded within their natal cores. Here we present high-spatial-resolution interferometric dust continuum observations disentangling the cluster-like structure of a young massive star-forming region. The derived protocluster mass distribution is consistent with the stellar initial mass function. Thus, fragmentation of the initial massive cores may determine the initial mass function and the masses of the final stars. This implies that stars of all masses can form via accretion processes, and coalescence of intermediate-mass protostars appears not to be necessary.

  10. DRAG COEFFICIENTS FOR IRREGULAR FRAGMENTS

    Science.gov (United States)

    1986-08-01

    regular fragments.were studied In the report, I.e., a sphere, a c-ibe and a bar. Th.a bar length, 1530) 77= pp. P width and thickness were. in the ratio...measurements for the 96 fragmento are contained in Tables A-1, A-2 and A-3 of Appendix A. The esiential aspects of the vertical wind tunnel are shown...THICKNESS L’ MAXIMUM LENGTH P ..UPS AVERAGE LENGTH W’ M AXIMUM WIDTH PLUS AVERAGE WIDTH T’ M I’XIX1MUM THICKNESS PLUS AVERAIE THICKNESS i -- STANDARO DEVIATION

  11. Experiments with Fluorescent Lamps

    Science.gov (United States)

    Kraftmakher, Yaakov

    2010-10-01

    The experiments described below show the irradiance and illuminance spectra of two fluorescent lamps in relation to their color temperatures, and the efficacy in comparison to that of an incandescent lamp. Spectra of "warm white" and "cool daylight" fluorescent lamps are demonstrated.

  12. LEDs for fluorescence microscopy

    NARCIS (Netherlands)

    Young, I.T.; Garini, Y.; Dietrich, H.R.C.; Van Oel, W.; Liqui Lung, G.

    2004-01-01

    Traditional light sources for fluorescence microscopy have been mercury lamps, xenon lamps, and lasers. These sources have been essential in the development of fluorescence microscopy but each can have serious disadvantages: lack of near monochromaticity, heat generation, cost, lifetime of the light

  13. Membranes and Fluorescence microscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2009-01-01

    Fluorescence spectroscopy-based techniques using conventional fluorimeters have been extensively applied since the late 1960s to study different aspects of membrane-related phenomena, i.e., mainly relating to lipid-lipid and lipid-protein (peptide) interactions. Even though fluorescence...

  14. Dihadron fragmentation functions for large invariant mass.

    Science.gov (United States)

    Zhou, J; Metz, A

    2011-04-29

    Using perturbative quantum chromodynamics, we compute dihadron fragmentation functions for a large invariant mass of the dihadron pair. The main focus is on the interference fragmentation function H(1)(∢), which plays an important role in spin physics of the nucleon. Our calculation also reveals that H(1)(∢) and the Collins fragmentation function have closely related underlying dynamics. By considering semi-inclusive deep-inelastic scattering, we further show that collinear factorization in terms of dihadron fragmentation functions and collinear factorization in terms of single-hadron fragmentation functions provide the same result in the region of intermediate invariant mass.

  15. Magmatic and fragmentation controls on volcanic ash surface chemistry

    Science.gov (United States)

    Ayris, Paul M.; Diplas, Spyros; Damby, David E.; Hornby, Adrian J.; Cimarelli, Corrado; Delmelle, Pierre; Scheu, Bettina; Dingwell, Donald B.

    2016-04-01

    The chemical effects of silicate ash ejected by explosive volcanic eruptions on environmental systems are fundamentally mediated by ash particle surfaces. Ash surfaces are a composite product of magmatic properties and fragmentation mechanisms, as well as in-plume and atmospheric alteration processes acting upon those surfaces during and after the eruption. Recent attention has focused on the capacity of alteration processes to shape ash surfaces; most notably, several studies have utilised X-ray photoelectron spectroscopy (XPS), a technique probing the elemental composition and coordination state of atoms within the top 10 nm of ash surfaces, to identify patterns of elemental depletions and enrichments relative to bulk ash chemical composition. Under the presumption of surface and bulk equivalence, any disparities have been previously attributed to surface alteration processes, but the ubiquity of some depletions (e.g., Ca, Fe) across multiple ash studies, irrespective of eruptive origin, could suggest these to be features of the surface produced at the instant of magma fragmentation. To investigate this possibility further, we conducted rapid decompression experiments at different pressure conditions and at ambient and magmatic temperature on porous andesitic rocks. These experiments produced fragmented ash material untouched by secondary alteration, which were compared to particles produced by crushing of large clasts from the same experiments. We investigated a restricted size fraction (63-90 μm) from both fragmented and crushed materials, determining bulk chemistry and mineralogy via XRF, SEM-BSE and EPMA, and investigated the chemical composition of the ash surface by XPS. Analyses suggest that fragmentation under experimental conditions partitioned a greater fraction of plagioclase-rich particles into the selected size fraction, relative to particles produced by crushing. Trends in surface chemical composition in fragmented and crushed particles mirror that

  16. Model tool to describe chemical structures in XML format utilizing structural fragments and chemical ontology.

    Science.gov (United States)

    Sankar, Punnaivanam; Alain, Krief; Aghila, Gnanasekaran

    2010-05-24

    We have developed a model structure-editing tool, ChemEd, programmed in JAVA, which allows drawing chemical structures on a graphical user interface (GUI) by selecting appropriate structural fragments defined in a fragment library. The terms representing the structural fragments are organized in fragment ontology to provide a conceptual support. ChemEd describes the chemical structure in an XML document (ChemFul) with rich semantics explicitly encoding the details of the chemical bonding, the hybridization status, and the electron environment around each atom. The document can be further processed through suitable algorithms and with the support of external chemical ontologies to generate understandable reports about the functional groups present in the structure and their specific environment.

  17. Multicolor, Fluorescent Supercapacitor Fiber.

    Science.gov (United States)

    Liao, Meng; Sun, Hao; Zhang, Jing; Wu, Jingxia; Xie, Songlin; Fu, Xuemei; Sun, Xuemei; Wang, Bingjie; Peng, Huisheng

    2017-10-05

    Fiber-shaped supercapacitors have attracted broad attentions from both academic and industrial communities due to the demonstrated potentials as next-generation power modules. However, it is important while remains challenging to develop dark-environment identifiable supercapacitor fibers for enhancement on operation convenience and security in nighttime applications. Herein, a novel family of colorful fluorescent supercapacitor fibers has been produced from aligned multi-walled carbon nanotube sheets. Fluorescent dye particles are introduced and stably anchored on the surfaces of aligned multi-walled carbon nanotubes to prepare hybrid fiber electrodes with a broad range of colors from red to purple. The fluorescent component in the dye introduces fluorescent indication capability to the fiber, which is particularly promising for flexible and wearable devices applied in dark environment. In addition, the colorful fluorescent supercapacitor fibers also maintain high electrochemical performance under cyclic bending and charge-discharge processes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Single-atom-resolved fluorescence imaging of an atomic Mott insulator

    DEFF Research Database (Denmark)

    Sherson, Jacob; Weitenberg, Christof; Andres, Manuel

    2010-01-01

    The reliable detection of single quantum particles has revolutionized the field of quantum optics and quantum information processing. For several years, researchers have aspired to extend such detection possibilities to larger-scale, strongly correlated quantum systems 1 , 2 in order to record in...

  19. Protein- protein interaction detection system using fluorescent protein microdomains

    Science.gov (United States)

    Waldo, Geoffrey S.; Cabantous, Stephanie

    2010-02-23

    The invention provides a protein labeling and interaction detection system based on engineered fragments of fluorescent and chromophoric proteins that require fused interacting polypeptides to drive the association of the fragments, and further are soluble and stable, and do not change the solubility of polypeptides to which they are fused. In one embodiment, a test protein X is fused to a sixteen amino acid fragment of GFP (.beta.-strand 10, amino acids 198-214), engineered to not perturb fusion protein solubility. A second test protein Y is fused to a sixteen amino acid fragment of GFP (.beta.-strand 11, amino acids 215-230), engineered to not perturb fusion protein solubility. When X and Y interact, they bring the GFP strands into proximity, and are detected by complementation with a third GFP fragment consisting of GFP amino acids 1-198 (strands 1-9). When GFP strands 10 and 11 are held together by interaction of protein X and Y, they spontaneous association with GFP strands 1-9, resulting in structural complementation, folding, and concomitant GFP fluorescence.

  20. Reframing landscape fragmentation's effects on ecosystem services.

    Science.gov (United States)

    Mitchell, Matthew G E; Suarez-Castro, Andrés F; Martinez-Harms, Maria; Maron, Martine; McAlpine, Clive; Gaston, Kevin J; Johansen, Kasper; Rhodes, Jonathan R

    2015-04-01

    Landscape structure and fragmentation have important effects on ecosystem services, with a common assumption being that fragmentation reduces service provision. This is based on fragmentation's expected effects on ecosystem service supply, but ignores how fragmentation influences the flow of services to people. Here we develop a new conceptual framework that explicitly considers the links between landscape fragmentation, the supply of services, and the flow of services to people. We argue that fragmentation's effects on ecosystem service flow can be positive or negative, and use our framework to construct testable hypotheses about the effects of fragmentation on final ecosystem service provision. Empirical efforts to apply and test this framework are critical to improving landscape management for multiple ecosystem services. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. The formation of planets by disc fragmentation

    Directory of Open Access Journals (Sweden)

    Stamatellos Dimitris

    2013-04-01

    Full Text Available I discuss the role that disc fragmentation plays in the formation of gas giant and terrestrial planets, and how this relates to the formation of brown dwarfs and low-mass stars, and ultimately to the process of star formation. Protostellar discs may fragment, if they are massive enough and can cool fast enough, but most of the objects that form by fragmentation are brown dwarfs. It may be possible that planets also form, if the mass growth of a proto-fragment is stopped (e.g. if this fragment is ejected from the disc, or suppressed and even reversed (e.g by tidal stripping. I will discuss if it is possible to distinguish whether a planet has formed by disc fragmentation or core accretion, and mention of a few examples of observed exoplanets that are suggestive of formation by disc fragmentation.

  2. Sleep fragmentation in canine narcolepsy.

    Science.gov (United States)

    Kaitin, K I; Kilduff, T S; Dement, W C

    1986-01-01

    Genetically narcoleptic dogs were recorded continuously for 24 h to examine their sleep-wake patterns and to evaluate the extent of sleep fragmentation. Three narcoleptic and three control dogs from each of two affected breeds (Labrador retrievers and Doberman pinschers) were surgically implanted with electrodes for recording standard sleep parameters. Recordings were scored in 30-s epochs for the states of active waking, drowsiness, light sleep, deep slow wave sleep, REM sleep, and cataplexy. All affected dogs displayed marked fragmentation and disruption of the sleep-wake cycle characterized by repeated awakenings, frequent shifts in sleep stages, numerous attacks of cataplexy occurring from active waking, and a disturbance of the normal REM-NREM periodicity. This sleep disruption was reflected in significantly greater numbers of episodes of each behavioral state as well as in a 38% increase in the total number of all states. These results demonstrate a severe disturbance of the normal sleep pattern in canine narcoleptics. The possibility of a general dysfunction of circadian organization is discussed.

  3. Dielectrophoretic immobilization of proteins: Quantification by atomic force microscopy.

    Science.gov (United States)

    Laux, Eva-Maria; Knigge, Xenia; Bier, Frank F; Wenger, Christian; Hölzel, Ralph

    2015-09-01

    The combination of alternating electric fields with nanometer-sized electrodes allows the permanent immobilization of proteins by dielectrophoretic force. Here, atomic force microscopy is introduced as a quantification method, and results are compared with fluorescence microscopy. Experimental parameters, for example the applied voltage and duration of field application, are varied systematically, and the influence on the amount of immobilized proteins is investigated. A linear correlation to the duration of field application was found by atomic force microscopy, and both microscopical methods yield a square dependence of the amount of immobilized proteins on the applied voltage. While fluorescence microscopy allows real-time imaging, atomic force microscopy reveals immobilized proteins obscured in fluorescence images due to low S/N. Furthermore, the higher spatial resolution of the atomic force microscope enables the visualization of the protein distribution on single nanoelectrodes. The electric field distribution is calculated and compared to experimental results with very good agreement to atomic force microscopy measurements. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Prospects of Optical Single Atom Detection for Nuclear Astrophysics

    Science.gov (United States)

    Singh, Jaideep

    2015-10-01

    We will discuss the prospects of optically detecting single atoms captured in a cryogenic thin film of a noble gas such as neon. This proposed detection scheme, when coupled with a recoil separator, could be used to measure rare nuclear reactions relevant for nuclear astrophysics. In particular, we will focus on the 22Ne(α, n)25Mg reaction, which is an important source of neutrons for the s-process. Noble gas solids are an attractive medium because they are optically transparent and provide efficient, pure, stable, & chemically inert confinement for a wide variety of atomic and molecular species. Atoms embedded inside of noble gas solids have a fluorescence spectrum that is often significantly shifted from its absorption spectrum. This makes possible the detection of individual fluorescence photons against a background of intense excitation light, which can be suppressed using the appropriate optical filters. We will report on our efforts to optically detect single Yb atoms in solid Ne. Yb is an ideal candidate for initial studies because it emits a strong green fluorescence when excited by blue light and it has an atomic structure that very closely resembles that of Mg. This work is supported by funds from Michigan State University.

  5. Development of Fluorescent Protein Probes Specific for Parallel DNA and RNA G-Quadruplexes.

    Science.gov (United States)

    Dang, Dung Thanh; Phan, Anh Tuân

    2016-01-01

    We have developed fluorescent protein probes specific for parallel G-quadruplexes by attaching cyan fluorescent protein to the G-quadruplex-binding motif of the RNA helicase RHAU. Fluorescent probes containing RHAU peptide fragments of different lengths were constructed, and their binding to G-quadruplexes was characterized. The selective recognition and discrimination of G-quadruplex topologies by the fluorescent protein probes was easily detected by the naked eye or by conventional gel imaging. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Talif quantification of nitrogen atoms applied to experimental simulation of Titan's atmosphere

    Science.gov (United States)

    Sebbar, Touhami Es; Yves, Benilan; Arzoumanian, Emmanuel; Gazeau, Marie-Claire

    Titan, Saturn's largest moon, has an atmosphere mainly composed of nitrogen ( 98 % N2 ) and methane ( 2 % CH4 ). In Titan's upper atmosphere, these compounds are dissociated by energetic electrons coming from the magnetosphere of Saturn and solar photons: nitrogen atoms and CH3 , CH2 and CH radicals are produced. The recombination of these fragments and the following complex chemistry leads finally to the formation of complex hydrocarbons and nitriles. Within the SETUP program (see presentation session F32), simulation experiments will be carried out with the aim to explicit the mechanisms involved in the chemical evolution of Titan's atmosphere. Indeed, the initial gas mixture (N2 /CH4 ) will be submitted in a dedicated reactor to an energy deposition, in situ time resolved analysis of the resulting sample (qualification and quantification of intermediates species, as well as stable compounds) will be performed by a laser technique (C.R.D.S.: Cavity Ring Down Spectroscopy). Representativeness of our simulations in term of energy deposition is ensured by the use of both UV photons (dissociation of CH4 by a continuous lamp or a pulsed laser) and electrons (dissociation of N2 by a cold plasma). One of our actual concern is to make sure that the cold plasma induces a ratio of nitrogen atoms versus dinitrogen molecules equivalent to the one existing in Titan's high atmosphere. Consequently, we are studying the N production in the reactor as the function of different parameters of the discharge: initial flow of N2 , discharge power, gas pressure and residence time. Quantification of N in its ground state is performed, by the Two photons Absorption Laser Induced Fluorescence technique (TALIF): a UV laser beam excitation at 206.6 nm [N (2p3 4 S 3/2 ) → N (3p 4 S3/2 ) transition] is used, the fluorescence is detected between 742 and 746 nm [N (3p 4 S3/2 ) → N (3s 4 P1/2,3/2,5/2 ) transition]. The TALIF measurements which give the relative nitrogen atom density are

  7. Atoms, Molecules, and Compounds

    CERN Document Server

    Manning, Phillip

    2007-01-01

    Explores the atoms that govern chemical processes. This book shows how the interactions between simple substances such as salt and water are crucial to life on Earth and how those interactions are predestined by the atoms that make up the molecules.

  8. Atoms, Molecules and Radiation

    Indian Academy of Sciences (India)

    IAS Admin

    A Refresher Course in Applications of Quantum Mechanics to 'Atoms, Molecules and Radiation' will be held at the Indian Academy of Sciences, Bangalore from December 8 to 20. 2014. The Course is primarily aimed at teachers teaching quantum mechanics and/ or atomic and molecular physics at the UG / PG level.

  9. When Atoms Want

    Science.gov (United States)

    Talanquer, Vicente

    2013-01-01

    Chemistry students and teachers often explain the chemical reactivity of atoms, molecules, and chemical substances in terms of purposes or needs (e.g., atoms want or need to gain, lose, or share electrons in order to become more stable). These teleological explanations seem to have pedagogical value as they help students understand and use…

  10. Atomicity in Electronic Commerce,

    Science.gov (United States)

    1996-01-01

    Atomicity in Electronic Commerce J. D. Tygar January 1996 CMU-CS-96-112 School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213...other research sponsor. Keywords: electronic commerce , atomicity, NetBill, IBIP, cryptography, transaction pro- cessing, ACID, franking, electronic ...goods over networks. Electronic commerce has inspired a large variety of work. Unfortunately, much of that work ignores traditional transaction

  11. Sensing of biomolecular interactions using fluorescence complementing systems in living cells.

    Science.gov (United States)

    Zhang, Xian-En; Cui, Zongqiang; Wang, Dianbing

    2016-02-15

    Sensing biomolecule interactions in living cells allows for a deeper understanding of the mechanisms governing biological processes, and has increasing significance for improvements in clinical diagnosis. It is now possible by using molecular biosensors. One method involving molecular biosensors is called molecular fluorescence complementation, usually referred to as BiFC (bimolecular fragment/fluorescence complementary/complementation) or TriFC (trimolecular fragment complementary/complementation). This complementation method is based on the principle that two non-fluorescent fragments of a fluorescent protein are brought into sufficient lyclose proximity, upon which they are reconstructed so that fluorescence is re-established. This process relies on the interaction between the two fusion partners, which normally are proteins. This method is simple, noninvasive, sensitive, and does not require specialized tools, hence being available to most standard laboratories. Here, we selectively describe three relevant examples, although many other molecular interactions have been shown to work with this method. Recent developments of this method include multicolor BiFC, which allows for simultaneous detection of multi-biomolecule interactions, RNA-protein interactions, far red and near infrared sensing systems for deep tissue imaging. Challenges in the utilization of this method are discussed. Given the current rate of technological advancements, we believe that fluorescence fragment complementing systems have the potential to be utilized across a wide range of areas, including in routine research and clinical diagnosis. Copyright © 2015. Published by Elsevier B.V.

  12. Embedded Fragments from U.S. Military Personnel—Chemical Analysis and Potential Health Implications

    Directory of Open Access Journals (Sweden)

    José A. Centeno

    2014-01-01

    Full Text Available Background: The majority of modern war wounds are characterized by high-energy blast injuries containing a wide range of retained foreign materials of a metallic or composite nature. Health effects of retained fragments range from local or systemic toxicities to foreign body reactions or malignancies, and dependent on the chemical composition and corrosiveness of the fragments in vivo. Information obtained by chemical analysis of excised fragments can be used to guide clinical decisions regarding the need for fragment removal, to develop therapeutic interventions, and to better anticipate future medical problems from retained fragment related injuries. In response to this need, a new U.S Department of Defense (DoD directive has been issued requiring characterization of all removed fragments to provide a database of fragment types occurring in combat injuries. Objectives: The objective of this study is to determine the chemical composition of retained embedded fragments removed from injured military personnel, and to relate results to histological findings in tissue adjacent to fragment material. Methods: We describe an approach for the chemical analysis and characterization of retained fragments and adjacent tissues, and include case examples describing fragments containing depleted uranium (DU, tungsten (W, lead (Pb, and non-metal foreign bodies composed of natural and composite materials. Fragments obtained from four patients with penetrating blast wounds to the limbs were studied employing a wide range of chemical and microscopy techniques. Available adjacent tissues from three of the cases were histologically, microscopically, and chemically examined. The physical and compositional properties of the removed foreign material surfaces were examined with energy dispersive x-ray fluorescence spectrometry (EDXRF, scanning electron microscopy (SEM, laser ablation inductively-coupled plasma mass-spectrometry (LA-ICP-MS, and confocal laser Raman

  13. Internal fluorescence labeling with fluorescent deoxynucleotides in two-label peak-height encoded DNA sequencing by capillary electrophoresis.

    Science.gov (United States)

    Starke, H R; Yan, J Y; Zhang, J Z; Mühlegger, K; Effgen, K; Dovichi, N J

    1994-09-25

    Fluorescently labeled deoxynucleotides were used for internal labeling of DNA sequencing fragments generated in a two-color peak-height encoded protocol. Sequenase and a manganese-containing buffer were used to generate uniform peak heights. Tetramethyl rhodamine - dATP was used in a labeling step, followed by termination with ddATP and ddCTP in a 3:1 ratio. Fluorescein - dATP was used in a second reaction, followed by termination with ddGTP and ddTTP in a 3:1 ratio. The fragments were pooled and separated by capillary gel electrophoresis. The results were compared with peak-height encoded sequencing based on fluorescently labeled primers. The dye-labeled primers produced higher resolution separations for shorter fragments. However, dye-labeled primer fragments suffered from an earlier onset of biased reptation and produced shorter sequencing reads. Fragments from 50 to at least 500 bases in length could be sequenced with the internal labels.

  14. Multipolar electrostatics for proteins: atom-atom electrostatic energies in crambin.

    Science.gov (United States)

    Yuan, Yongna; Mills, Matthew J L; Popelier, Paul L A

    2014-02-15

    Accurate electrostatics necessitates the use of multipole moments centered on nuclei or extra point charges centered away from the nuclei. Here, we follow the former alternative and investigate the convergence behavior of atom-atom electrostatic interactions in the pilot protein crambin. Amino acids are cut out from a Protein Data Bank structure of crambin, as single amino acids, di, or tripeptides, and are then capped with a peptide bond at each side. The atoms in the amino acids are defined through Quantum Chemical Topology (QCT) as finite volume electron density fragments. Atom-atom electrostatic energies are computed by means of a multipole expansion with regular spherical harmonics, up to a total interaction rank of L = ℓA+ ℓB + 1 = 10. The minimum internuclear distance in the convergent region of all the 15 possible types of atom-atom interactions in crambin that were calculated based on single amino acids are close to the values calculated from di and tripeptides. Values obtained at B3LYP/aug-cc-pVTZ and MP2/aug-cc-pVTZ levels are only slightly larger than those calculated at HF/6-31G(d,p) level. This convergence behavior is transferable to the well-known amyloid beta polypeptide Aβ1-42. Moreover, for a selected central atom, the influence of its neighbors on its multipole moments is investigated, and how far away this influence can be ignored is also determined. Finally, the convergence behavior of AMBER becomes closer to that of QCT with increasing internuclear distance. Copyright © 2013 Wiley Periodicals, Inc.

  15. Theoretical atomic physics

    CERN Document Server

    Friedrich, Harald

    2017-01-01

    This expanded and updated well-established textbook contains an advanced presentation of quantum mechanics adapted to the requirements of modern atomic physics. It includes topics of current interest such as semiclassical theory, chaos, atom optics and Bose-Einstein condensation in atomic gases. In order to facilitate the consolidation of the material covered, various problems are included, together with complete solutions. The emphasis on theory enables the reader to appreciate the fundamental assumptions underlying standard theoretical constructs and to embark on independent research projects. The fourth edition of Theoretical Atomic Physics contains an updated treatment of the sections involving scattering theory and near-threshold phenomena manifest in the behaviour of cold atoms (and molecules). Special attention is given to the quantization of weakly bound states just below the continuum threshold and to low-energy scattering and quantum reflection just above. Particular emphasis is laid on the fundamen...

  16. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  17. Maximally Atomic Languages

    Directory of Open Access Journals (Sweden)

    Janusz Brzozowski

    2014-05-01

    Full Text Available The atoms of a regular language are non-empty intersections of complemented and uncomplemented quotients of the language. Tight upper bounds on the number of atoms of a language and on the quotient complexities of atoms are known. We introduce a new class of regular languages, called the maximally atomic languages, consisting of all languages meeting these bounds. We prove the following result: If L is a regular language of quotient complexity n and G is the subgroup of permutations in the transition semigroup T of the minimal DFA of L, then L is maximally atomic if and only if G is transitive on k-subsets of 1,...,n for 0 <= k <= n and T contains a transformation of rank n-1.

  18. Nondestructive light-shift measurements of single atoms in optical dipole traps

    Science.gov (United States)

    Shih, Chung-Yu; Chapman, Michael S.

    2013-06-01

    We measure the ac Stark shifts of the 5S1/2,F=2→5P3/2,F'=3 transitions of individual optically trapped 87Rb atoms using a nondestructive detection technique that allows us to measure the fluorescent signal of one and the same atom for over 60 s. These measurements allow the efficient and rapid characterization of single-atom traps that is required for many coherent quantum information protocols. Although this method is demonstrated using a single-atom trap, the concept is readily extended to resolvable atomic arrays.

  19. Combined AFM and confocal fluorescence microscope for applications in bio-nanotechnology

    NARCIS (Netherlands)

    Kassies, R.; van der Werf, Kees; Lenferink, Aufrid T.M.; Hunter, C.N.; Olsen, J.D.; Subramaniam, Vinod; Otto, Cornelis

    2005-01-01

    We present a custom-designed atomic force fluorescence microscope (AFFM), which can perform simultaneous optical and topographic measurements with single molecule sensitivity throughout the whole visible to near-infrared spectral region. Integration of atomic force microscopy (AFM) and confocal

  20. Fluorescence and Spectral Imaging

    Directory of Open Access Journals (Sweden)

    Ralph S. DaCosta

    2007-01-01

    Full Text Available Early identification of dysplasia remains a critical goal for diagnostic endoscopy since early discovery directly improves patient survival because it allows endoscopic or surgical intervention with disease localized without lymph node involvement. Clinical studies have successfully used tissue autofluorescence with conventional white light endoscopy and biopsy for detecting adenomatous colonic polyps, differentiating benign hyperplastic from adenomas with acceptable sensitivity and specificity. In Barrett's esophagus, the detection of dysplasia remains problematic because of background inflammation, whereas in the squamous esophagus, autofluorescence imaging appears to be more dependable. Point fluorescence spectroscopy, although playing a crucial role in the pioneering mechanistic development of fluorescence endoscopic imaging, does not seem to have a current function in endoscopy because of its nontargeted sampling and suboptimal sensitivity and specificity. Other point spectroscopic modalities, such as Raman spectroscopy and elastic light scattering, continue to be evaluated in clinical studies, but still suffer the significant disadvantages of being random and nonimaging. A recent addition to the fluorescence endoscopic imaging arsenal is the use of confocal fluorescence endomicroscopy, which provides real-time optical biopsy for the first time. To improve detection of dysplasia in the gastrointestinal tract, a new and exciting development has been the use of exogenous fluorescence contrast probes that specifically target a variety of disease-related cellular biomarkers using conventional fluorescent dyes and novel potent fluorescent nanocrystals (i.e., quantum dots. This is an area of great promise, but still in its infancy, and preclinical studies are currently under way.

  1. ADVANCED APPROACHES TO ARSINE ATOMIZATION FOR AS SPECIATION BY CRYOFOCUSING WITH ATOMIC ABSORPTION AND ATOMIC FLUORESCENCE DETECTORS

    Science.gov (United States)

    Human metabolism of inorganic arsenic (iAs) yields methylated arsenicals that contain arsenic in +3 or +5 oxidation state. Trivalent methylated arsenicals are significantly more toxic than their pentavalent counterparts. Therefore, determination of tri- and pentavalent forms of m...

  2. Internal fluorescence labeling with fluorescent deoxynucleotides in two-label peak-height encoded DNA sequencing by capillary electrophoresis.

    OpenAIRE

    Starke, H R; J. Y. Yan; ZHANG, J. Z.; Mühlegger, K; Effgen, K; Dovichi, N J

    1994-01-01

    Fluorescently labeled deoxynucleotides were used for internal labeling of DNA sequencing fragments generated in a two-color peak-height encoded protocol. Sequenase and a manganese-containing buffer were used to generate uniform peak heights. Tetramethyl rhodamine - dATP was used in a labeling step, followed by termination with ddATP and ddCTP in a 3:1 ratio. Fluorescein - dATP was used in a second reaction, followed by termination with ddGTP and ddTTP in a 3:1 ratio. The fragments were pooled...

  3. Highly thermostable fluorescent proteins

    Science.gov (United States)

    Bradbury, Andrew M [Santa Fe, NM; Waldo, Geoffrey S [Santa Fe, NM; Kiss, Csaba [Los Alamos, NM

    2012-05-01

    Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

  4. Fluorescent discharge lamp

    Science.gov (United States)

    Mukai, E.; Otsuka, H.; Nomi, K.; Honmo, I.

    1982-01-01

    A rapidly illuminating fluorescent lamp 1,200 mm long and 32.5 mm in diameter with an interior conducting strip which is compatible with conventional fixtures and ballasts is described. The fluorescent lamp is composed of a linear glass tube, electrodes sealed at both ends, mercury and raregas sealed in the glass tube, a fluorescent substance clad on the inner walls of the glass tube, and a clad conducting strip extending the entire length of the glass tube in the axial direction on the inner surface of the tube.

  5. Fluorescent discharge lamp

    Science.gov (United States)

    Mukai, E.; Otsuka, H.; Nomi, K.; Honmo, I.

    1982-07-01

    A rapidly illuminating fluorescent lamp 1,200 mm long and 32.5 mm in diameter with an interior conducting strip which is compatible with conventional fixtures and ballasts is described. The fluorescent lamp is composed of a linear glass tube, electrodes sealed at both ends, mercury and raregas sealed in the glass tube, a fluorescent substance clad on the inner walls of the glass tube, and a clad conducting strip extending the entire length of the glass tube in the axial direction on the inner surface of the tube.

  6. Highly thermostable fluorescent proteins

    Science.gov (United States)

    Bradbury, Andrew M [Santa Fe, NM; Waldo, Geoffrey S [Santa Fe, NM; Kiss, Csaba [Los Alamos, NM

    2011-03-22

    Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

  7. Single chain Fab (scFab fragment

    Directory of Open Access Journals (Sweden)

    Brenneis Mariam

    2007-03-01

    Full Text Available Abstract Background The connection of the variable part of the heavy chain (VH and and the variable part of the light chain (VL by a peptide linker to form a consecutive polypeptide chain (single chain antibody, scFv was a breakthrough for the functional production of antibody fragments in Escherichia coli. Being double the size of fragment variable (Fv fragments and requiring assembly of two independent polypeptide chains, functional Fab fragments are usually produced with significantly lower yields in E. coli. An antibody design combining stability and assay compatibility of the fragment antigen binding (Fab with high level bacterial expression of single chain Fv fragments would be desirable. The desired antibody fragment should be both suitable for expression as soluble antibody in E. coli and antibody phage display. Results Here, we demonstrate that the introduction of a polypeptide linker between the fragment difficult (Fd and the light chain (LC, resulting in the formation of a single chain Fab fragment (scFab, can lead to improved production of functional molecules. We tested the impact of various linker designs and modifications of the constant regions on both phage display efficiency and the yield of soluble antibody fragments. A scFab variant without cysteins (scFabΔC connecting the constant part 1 of the heavy chain (CH1 and the constant part of the light chain (CL were best suited for phage display and production of soluble antibody fragments. Beside the expression system E. coli, the new antibody format was also expressed in Pichia pastoris. Monovalent and divalent fragments (DiFabodies as well as multimers were characterised. Conclusion A new antibody design offers the generation of bivalent Fab derivates for antibody phage display and production of soluble antibody fragments. This antibody format is of particular value for high throughput proteome binder generation projects, due to the avidity effect and the possible use of

  8. Atomic transition probabilities of Er i

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J E; Den Hartog, E A [Department of Physics, University of Wisconsin, 1150 University Ave., Madison, WI 53706 (United States); Wyart, J-F, E-mail: jelawler@wisc.ed, E-mail: jean-francois.wyart@lac.u-psud.f, E-mail: eadenhar@wisc.ed [Laboratoire Aime Cotton, CNRS (UPR3321), Bat. 505, Centre Universitaire Paris-Sud, 91405-Orsay (France)

    2010-12-14

    Atomic transition probabilities for 562 lines of the first spectrum of erbium (Er i) are reported. These data are from new branching fraction measurements on Fourier transform spectra normalized with previously reported radiative lifetimes from time-resolved laser-induced fluorescence measurements (Den Hartog et al 2010 J. Phys. B: At. Mol. Opt. Phys. 43 155004). The wavelength range of the data set is from 298 to 1981 nm. In this work we explore the utility of parametric fits based on the Cowan code in assessing branching fraction errors due to lines connecting to unobserved lower levels.

  9. Atomic transition probabilities of Gd i

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J E; Den Hartog, E A [Department of Physics, University of Wisconsin, 1150 University Avenue, Madison, WI 53706 (United States); Bilty, K A, E-mail: jelawler@wisc.edu, E-mail: biltyka@uwec.edu, E-mail: eadenhar@wisc.edu [Department of Physics and Astronomy, University of Wisconsin-Eau Claire, Eau Claire, WI 54702 (United States)

    2011-05-14

    Fourier transform spectra are used to determine emission branching fractions for 1290 lines of the first spectrum of gadolinium (Gd i). These branching fractions are converted to absolute atomic transition probabilities using previously reported radiative lifetimes from time-resolved laser-induced-fluorescence measurements (Den Hartog et al 2011 J. Phys. B: At. Mol. Opt. Phys. 44 055001). The wavelength range of the data set is from 300 to 1850 nm. A least squares technique for separating blends of the first and second spectra lines is also described and demonstrated in this work.

  10. Fluid fragmentation from hospital toilets

    CERN Document Server

    Traverso, G; Lu, C -C; Maa, R; Langer, R; Bourouiba, L

    2013-01-01

    Hospital-acquired infections represent significant health and financial burdens to society. Clostridium difficile (C. difficile) is a particularly challenging bacteria with the potential to cause severe diarrhea and death. One mode of transmission for C. difficile, as well as other pathogens, which has received little attention is the potential air contamination by pathogen-bearing droplets emanating from toilets. In the fluid dynamics video submitted to the APS DFD Gallery of Fluid Motion 2013, we present flow visualizations via high-speed recordings showing the capture of the product of the fluid fragmentation generated by hospital toilet high-pressure flushes. Important quantities of both large and small droplets are observed. We illustrate how high-pressure flushes and cleaning products currently used in hospital toilets result in aggravating, rather than alleviating, the suspension and recirculation of tenacious airborne pathogen-bearing droplets.

  11. Fluorescent magnetic hybrid nanoprobe for multimodal bioimaging

    Energy Technology Data Exchange (ETDEWEB)

    Koktysh, Dmitry [Department of Chemistry, Vanderbilt University, Station B 351822, Nashville, TN 37235 (United States); Bright, Vanessa; Pham, Wellington, E-mail: dmitry.koktysh@vanderbilt.edu, E-mail: wellington.pham@vanderbilt.edu [Institute of Imaging Science, Vanderbilt University, 1161 21st Avenue South AA, 1105 MCN, Nashville, TN 37232 (United States)

    2011-07-08

    A fluorescent magnetic hybrid imaging nanoprobe (HINP) was fabricated by the conjugation of superparamagnetic Fe{sub 3}O{sub 4} nanoparticles and visible light emitting ({approx}600 nm) fluorescent CdTe/CdS quantum dots (QDs). The assembly strategy used the covalent linking of the oxidized dextran shell of magnetic particles to the glutathione ligands of QDs. The synthesized HINP formed stable water-soluble colloidal dispersions. The structure and properties of the particles were characterized by transmission electron and atomic force microscopy, energy dispersive x-ray analysis and inductively coupled plasma optical emission spectroscopy, dynamic light scattering analysis, optical absorption and photoluminescence spectroscopy, and fluorescent imaging. The luminescence imaging region of the nanoprobe was extended to the near-infrared (NIR) ({approx}800 nm) by conjugation of the superparamagnetic nanoparticles with synthesized CdHgTe/CdS QDs. Cadmium, mercury based QDs in HINP can be easily replaced by novel water-soluble glutathione stabilized AgInS{sub 2}/ZnS QDs to present a new class of cadmium-free multimodal imaging agents. The observed NIR photoluminescence of fluorescent magnetic nanocomposites supports their use for bioimaging. The developed HINP provides dual-imaging channels for simultaneous optical and magnetic resonance imaging.

  12. Fluorescent magnetic hybrid nanoprobe for multimodal bioimaging

    Science.gov (United States)

    Koktysh, Dmitry; Bright, Vanessa; Pham, Wellington

    2011-07-01

    A fluorescent magnetic hybrid imaging nanoprobe (HINP) was fabricated by the conjugation of superparamagnetic Fe3O4 nanoparticles and visible light emitting (~600 nm) fluorescent CdTe/CdS quantum dots (QDs). The assembly strategy used the covalent linking of the oxidized dextran shell of magnetic particles to the glutathione ligands of QDs. The synthesized HINP formed stable water-soluble colloidal dispersions. The structure and properties of the particles were characterized by transmission electron and atomic force microscopy, energy dispersive x-ray analysis and inductively coupled plasma optical emission spectroscopy, dynamic light scattering analysis, optical absorption and photoluminescence spectroscopy, and fluorescent imaging. The luminescence imaging region of the nanoprobe was extended to the near-infrared (NIR) (~800 nm) by conjugation of the superparamagnetic nanoparticles with synthesized CdHgTe/CdS QDs. Cadmium, mercury based QDs in HINP can be easily replaced by novel water-soluble glutathione stabilized AgInS2/ZnS QDs to present a new class of cadmium-free multimodal imaging agents. The observed NIR photoluminescence of fluorescent magnetic nanocomposites supports their use for bioimaging. The developed HINP provides dual-imaging channels for simultaneous optical and magnetic resonance imaging.

  13. Changing blue fluorescent protein to green fluorescent protein using chemical RNA editing as a novel strategy in genetic restoration.

    Science.gov (United States)

    Vu, Luyen T; Nguyen, Thanh T K; Alam, Shafiul; Sakamoto, Takashi; Fujimoto, Kenzo; Suzuki, Hitoshi; Tsukahara, Toshifumi

    2015-11-01

    Using the transition from cytosine of BFP (blue fluorescent protein) gene to uridine of GFP (green fluorescent protein) gene at position 199 as a model, we successfully controlled photochemical RNA editing to effect site-directed deamination of cytidine (C) to uridine (U). Oligodeoxynucleotides (ODNs) containing 5'-carboxyvinyl-2'-deoxyuridine ((CV) U) were used for reversible photoligation, and single-stranded 100-nt BFP DNA and in vitro-transcribed full-length BFP mRNA were the targets. Photo-cross-linking with the responsive ODNs was performed using UV (366 nm) irradiation, which was followed by heat treatment, and the cross-linked nucleotide was cleaved through photosplitting (UV, 312 nm). The products were analyzed using restriction fragment length polymorphism (RFLP) and fluorescence measurements. Western blotting and fluorescence-analysis results revealed that in vitro-translated proteins were synthesized from mRNAs after site-directed RNA editing. We detected substantial amounts of the target-base-substituted fragment using RFLP and observed highly reproducible spectra of the transition-GFP signal using fluorescence spectroscopy, which indicated protein stability. ODNc restored approximately 10% of the C-to-U transition. Thus, we successfully used non-enzymatic site-directed deamination for genetic restoration in vitro. In the near future, in vivo studies that include cultured cells and model animals will be conducted to treat genetic disorders. © 2015 John Wiley & Sons A/S.

  14. Quantum caustics in resonance-fluorescence trajectories

    Science.gov (United States)

    Naghiloo, M.; Tan, D.; Harrington, P. M.; Lewalle, P.; Jordan, A. N.; Murch, K. W.

    2017-11-01

    We employ phase-sensitive amplification to perform homodyne detection of the resonance fluorescence from a driven superconducting artificial atom. Entanglement between the emitter and its fluorescence allows us to track the individual quantum state trajectories of the emitter conditioned on the outcomes of the field measurements. We analyze the ensemble properties of these trajectories by considering trajectories that connect specific initial and final states. By applying the stochastic path-integral formalism, we calculate equations of motion for the most-likely path between two quantum states and compare these predicted paths to experimental data. Drawing on the mathematical similarity between the action formalism of the most-likely quantum paths and ray optics, we study the emergence of caustics in quantum trajectories: places where multiple extrema in the stochastic action occur. We observe such multiple most-likely paths in experimental data and find these paths to be in reasonable quantitative agreement with theoretical calculations.

  15. High yield DNA fragmentation using cyclical hydrodynamic shearing

    NARCIS (Netherlands)

    Shui, Lingling; Sparreboom, Wouter; Spang, Peter; Roeser, Tina; Nieto, Benjamin; Guasch, Francesc; Corbera, Antoni Homs; van den Berg, Albert; Carlen, Edwin

    2013-01-01

    We report a new DNA fragmentation technique that significantly simplifies conventional hydrodynamic shearing fragmentation by eliminating the need for sample recirculation while maintaining high fragmentation yield and low fragment length variation, and therefore, reduces instrument complexity and

  16. Determination of absolute population densities of eroded tungsten in hollow cathode lamps and fluorescent lamps by laser-induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Hadrath, S [Institute of Low-Temperature Plasma Physics, Friedrich-Ludwig-Jahn-Str. 19, D-17489 Greifswald (Germany); Ehlbeck, J [Institute of Low-Temperature Plasma Physics, Friedrich-Ludwig-Jahn-Str. 19, D-17489 Greifswald (Germany); Lieder, G [Research Light Sources, Osram GmbH, Hellabrunner Str. 1, D 81536 Muenchen (Germany); Sigeneger, F [Institute of Low-Temperature Plasma Physics, Friedrich-Ludwig-Jahn-Str. 19, D-17489 Greifswald (Germany)

    2005-09-07

    The high energy ion bombardment during instant start of a fluorescent lamp (FL) leads to intense sputtering of the electrode material including tungsten and emitter. Thus, a cold started FL often suffers from early failures due to coil fracture. The main goal of this paper is to investigate tungsten erosion. We have employed the ultra-sensitive method of laser-induced fluorescence. This technique is particularly well-suited to determining absolute population densities of neutral and singly ionized atoms of liberated electrode material. In addition to FL, our investigations have been performed also on hollow cathode lamps (HCLs). These are useful because they provide a variable source of sputtered tungsten atoms and can serve as tuning tools for precise adjustment of the laser radiation. We will present absolute atomic tungsten population densities in a commercial FL and in an HCL. Furthermore, the results of a theoretical investigation of the argon plasma and the tungsten density in the HCL are represented.

  17. Single-atom nanoelectronics

    CERN Document Server

    Prati, Enrico

    2013-01-01

    Single-Atom Nanoelectronics covers the fabrication of single-atom devices and related technology, as well as the relevant electronic equipment and the intriguing new phenomena related to single-atom and single-electron effects in quantum devices. It also covers the alternative approaches related to both silicon- and carbon-based technologies, also from the point of view of large-scale industrial production. The publication provides a comprehensive picture of the state of the art at the cutting edge and constitutes a milestone in the emerging field of beyond-CMOS technology. Although there are

  18. Physics of the atom

    CERN Document Server

    Wehr, Russell M; Adair, Thomas W

    1984-01-01

    The fourth edition of Physics of the Atom is designed to meet the modern need for a better understanding of the atomic age. It is an introduction suitable for students with a background in university physics and mathematical competence at the level of calculus. This book is designed to be an extension of the introductory university physics course into the realm of atomic physics. It should give students a proficiency in this field comparable to their proficiency in mechanics, heat, sound, light, and electricity.

  19. Fluorescent radiation converter

    Science.gov (United States)

    Viehmann, W. (Inventor)

    1981-01-01

    A fluorescence radiation converter is described which includes a substantially undoped optically transparent substrate and a waveshifter coating deposited on at least one portion of the substrate for absorption of radiation and conversion of fluorescent radiation. The coating is formed to substantially 1000 g/liter of a solvent, 70 to 200 g/liter of an organic polymer, and 0.2 to 25 g/liter of at least one organic fluorescent dye. The incoming incident radiation impinges on the coating. Radiation is absorbed by the fluorescent dye and is re-emitted as a longer wavelength radiation. Radiation is trapped within the substrate and is totally internally reflected by the boundary surface. Emitted radiation leaves the substrate ends to be detected.

  20. Fluorescent filtered electrophosphorescence

    Science.gov (United States)

    Forrest, Stephen R [Princeton, NJ; Sun, Yiru [Princeton, NJ; Giebink, Noel [Princeton, NJ; Thompson, Mark E [Anaheim Hills, CA

    2009-01-06

    The present invention relates to organic light emitting devices (OLEDs), and more specifically to OLEDS that emit light using a combination of fluorescent emitters and phosphorescent emitters for the efficient utilization of all of the electrically generated excitons.

  1. Introduction to fluorescence

    CERN Document Server

    Jameson, David M

    2014-01-01

    "An essential contribution to educating scientists in the principles of fluorescence. It will also be an important addition to the libraries of practitioners applying the principles of molecular fluorescence."-Ken Jacobson, Kenan Distinguished Professor of Cell Biology and Physiology, University of North Carolina at Chapel Hill"An exquisite compendium of fluorescence and its applications in biochemistry enriched by a very exciting historical perspective. This book will become a standard text for graduate students and other scientists."-Drs. Zygmunt (Karol) Gryczynski and Ignacy Gryczynski, University of North Texas Health Science Center"… truly a masterwork, combining clarity, precision, and good humor. The reader, novice or expert, will be pleased with the text and will not stop reading. It is a formidable account of the fluorescence field, which has impacted the life sciences so considerably in the last 60 years."-Jerson L. Silva, M.D., Ph.D., Professor and Director, National Institute of Science and Tech...

  2. Fluorescence (Multiwave) Confocal Microscopy.

    Science.gov (United States)

    Welzel, J; Kästle, Raphaela; Sattler, Elke C

    2016-10-01

    In addition to reflectance confocal microscopy, multiwave confocal microscopes with different laser wavelengths in combination with exogenous fluorophores allow fluorescence mode confocal microscopy in vivo and ex vivo. Fluorescence mode confocal microscopy improves the contrast between the epithelium and the surrounding soft tissue and allows the depiction of certain structures, like epithelial tumors, nerves, and glands. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Advanced in X-ray fluorescence holography

    CERN Document Server

    Hayashi, K

    2002-01-01

    X-ray fluorescence holography (XFH) can resolve 'phase problem' in crystal diffraction and therefore it provides 3D atomic images around specific elements. Since first demonstration of the XFH in 1996, view of atoms has been improved rapidly with the refinement of the hologram data collection method. The present performance of the XFH makes it possible to apply to impurity, thin film and quasicrystal, and opens a way to practical tool for determination of local structure. In this paper, theory including solutions for twin image problem, advanced experimental systems and application to Si sub 0 sub . sub 9 sub 9 sub 9 Ge sub 0 sub . sub 0 sub 0 sub 1 are discussed. (author)

  4. Filter for interpretation of fragmentation during entry

    Energy Technology Data Exchange (ETDEWEB)

    Canavan, G.H.

    1997-10-01

    Objects that fragment cascade and decelerate abruptly, producing short, bright, signatures which can be used to estimate object diameter and speed. Other objects can be incorporated into a generalized fragmentation filter. This note summarizes the results of previous reports on the prediction and inversion of signatures from objects that radiate, ablate, and fragment during entry and uses them to produce models for the parameters of entering objects.

  5. Interaction of three fission fragments and yields of various ternary fragments

    Science.gov (United States)

    Denisov, V. Yu.; Pilipenko, N. A.; Sedykh, I. Yu.

    2017-01-01

    The interaction potential energy of the three deformed fragments formed in fission of 252Cf is studied for various combinations of three-fragment fission. The lowest height of the potential energy ridge between three touching and separated deformed fragments is sought. The excitation energies of various three-deformed-fragment configurations, at the lowest barrier heights related to the yield of the corresponding configuration, are considered in detail. The most probable three-fragment fission configurations are discussed. The yields of various ternary fragments in fission of 250Cf agree well with available experimental data.

  6. Fluorescence-based biosensors.

    Science.gov (United States)

    Strianese, Maria; Staiano, Maria; Ruggiero, Giuseppe; Labella, Tullio; Pellecchia, Claudio; D'Auria, Sabato

    2012-01-01

    The field of optical sensors has been a growing research area over the last three decades. A wide range of books and review articles has been published by experts in the field who have highlighted the advantages of optical sensing over other transduction methods. Fluorescence is by far the method most often applied and comes in a variety of schemes. Nowadays, one of the most common approaches in the field of optical biosensors is to combine the high sensitivity of fluorescence detection in combination with the high selectivity provided by ligand-binding proteins. In this chapter we deal with reviewing our recent results on the implementation of fluorescence-based sensors for monitoring environmentally hazardous gas molecules (e.g. nitric oxide, hydrogen sulfide). Reflectivity-based sensors, fluorescence correlation spectroscopy-based (FCS) systems, and sensors relying on the enhanced fluorescence emission on silver island films (SIFs) coupled to the total internal reflection fluorescence mode (TIRF) for the detection of gliadin and other prolamines considered toxic for celiac patients are also discussed herein.

  7. Coherent control of indirect photofragmentation in the weak-field limit: Control of transient fragment distributions

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Henriksen, Niels Engholm

    2011-01-01

    We demonstrate theoretically that laser-induced coherent quantum interference control of asymptotic states of dissociating molecules is possible - even in the (one-photon) weak-field limit starting from a single vibrational eigenstate - when resonances are in play. This is illustrated for the Na......I molecule, where it is shown that the probability of observing atomic fragments as well as the distribution of their relative momenta can be changed by a phase modulated pulse with a fixed bandwidth. This type of control is restricted to finite times during the indirect fragmentation. (C) 2011 American...

  8. Electronic Predetermination of Ethylene Fragmentation Dynamics

    Directory of Open Access Journals (Sweden)

    Xinhua Xie

    2014-04-01

    Full Text Available We experimentally investigate the dependence of the fragmentation behavior of the ethylene dication on the intensity and duration of the laser pulses that initiate the fragmentation dynamics by strong-field double ionization. Using coincidence momentum imaging for the detection of ionic fragments, we disentangle the different contributions of ionization from lower-valence orbitals and field-driven excitation dynamics to the population of certain dissociative excited ionic states that are connected to one of several possible fragmentation pathways towards a given set of fragment ions. We find that the excitation probability to a particular excited state and therewith the outcome of the fragmentation reaction strongly depend on the parameters of the laser pulse. This, in turn, opens up new possibilities for controlling the outcome of fragmentation reactions of polyatomic molecules in that it may allow one to selectively enhance or suppress individual fragmentation channels, which was not possible in previous attempts of controlling fragmentation processes of polyatomic molecules with strong laser fields.

  9. Excited state N2+(B˜) fragments from the photodissociation of N4+ at 270-290 nm

    Science.gov (United States)

    Ostrander, Scott C.; Weisshaar, James C.

    1986-08-01

    The photodissociation spectrum of N4+ from 270 to 310 nm is broad and structureless at 300 K, with the cross section diminishing by a factor of 10 towards shorter wavelengths. We have detected fluorescence from N2+(B˜) excited state fragments having quantum yield < 0.01 and risetime < 10 ns. The threshold at λ ≈ 300 nm indicates no exit channel barrier.

  10. Atomic & Molecular Interactions

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-07-12

    The Gordon Research Conference (GRC) on Atomic & Molecular Interactions was held at Roger Williams University, Bristol, RI. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  11. The Casimir atomic pendulum

    Energy Technology Data Exchange (ETDEWEB)

    Razmi, H. [Department of Physics, University of Qom, Qom 37185-359 (Iran, Islamic Republic of)], E-mail: razmi@qom.ac.ir; Abdollahi, M. [Department of Physics, University of Qom, Qom 37185-359 (Iran, Islamic Republic of)], E-mail: mah.abdollahi@gmail.com

    2008-11-10

    We want to introduce an atomic pendulum whose driving force (torque) is due to the quantum vacuum fluctuations. Applying the well-known Casimir-Polder effect to a special configuration (a combined structure of an atomic nanostring and a conducting plate), an atomic pendulum (Casimir atomic pendulum) is designed. Using practically acceptable data corresponding to the already known world of nanotechnology and based on reasonable/reliable numerical estimates, the period of oscillation for the pendulum is computed. This pendulum can be considered as both a new micro(nano)-electromechanical system and a new simple vacuum machine. Its design may be considered as a first step towards realizing the visualized vacuum (Casimir) clock{exclamation_point}.

  12. The Casimir atomic pendulum

    Science.gov (United States)

    Razmi, H.; Abdollahi, M.

    2008-11-01

    We want to introduce an atomic pendulum whose driving force (torque) is due to the quantum vacuum fluctuations. Applying the well-known Casimir-Polder effect to a special configuration (a combined structure of an atomic nanostring and a conducting plate), an atomic pendulum (Casimir atomic pendulum) is designed. Using practically acceptable data corresponding to the already known world of nanotechnology and based on reasonable/reliable numerical estimates, the period of oscillation for the pendulum is computed. This pendulum can be considered as both a new micro(nano)-electromechanical system and a new simple vacuum machine. Its design may be considered as a first step towards realizing the visualized vacuum (Casimir) clock!

  13. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    1998-01-01

    This volume continues the series'' cutting-edge reviews on developments in this field. Since its invention in the 1920s, electrostatic precipitation has been extensively used in industrial hygiene to remove dust and particulate matter from gases before entering the atmosphere. This combination of electrostatic precipitation is reported upon in the first chapter. Following this, chapter two reviews recent advances in the area of chemical modification in electrothermal atomization. Chapter three consists of a review which deal with advances and uses of electrothermal atomization atomic absorption spectrometry. Flow injection atomic spectroscopy has developed rapidly in recent years and after a general introduction, various aspects of this technique are looked at in chapter four. Finally, in chapter five the use of various spectrometric techniques for the determination of mercury are described.

  14. Dalton's Atomic Theory

    National Research Council Canada - National Science Library

    DOBBIN, LEONARD

    1896-01-01

    WITH reference to the communications from the authors and from the reviewer of the "New View of the Origin of Dalton's Atomic Theory," published in NATURE for May 14, I beg leave to offer the following remarks...

  15. Atomic Interferometry Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Vertical cavity surface emitting lasers (VCSELs) is a new technology which can be used for developing high performance laser components for atom-based sensors...

  16. Topics in atomic physics

    CERN Document Server

    Burkhardt, Charles E

    2006-01-01

    The study of atomic physics propelled us into the quantum age in the early twentieth century and carried us into the twenty-first century with a wealth of new and, in some cases, unexplained phenomena. Topics in Atomic Physics provides a foundation for students to begin research in modern atomic physics. It can also serve as a reference because it contains material that is not easily located in other sources. A distinguishing feature is the thorough exposition of the quantum mechanical hydrogen atom using both the traditional formulation and an alternative treatment not usually found in textbooks. The alternative treatment exploits the preeminent nature of the pure Coulomb potential and places the Lenz vector operator on an equal footing with other operators corresponding to classically conserved quantities. A number of difficult to find proofs and derivations are included as is development of operator formalism that permits facile solution of the Stark effect in hydrogen. Discussion of the classical hydrogen...

  17. Zeeman atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hadeishi, T.; McLaughlin, R.

    1978-08-01

    The design and development of a Zeeman atomic absorption spectrometer for trace element analysis are described. An instruction manual is included which details the operation, adjustment, and maintenance. Specifications and circuit diagrams are given. (WHK)

  18. Effects of pretreatment on the denaturation and fragmentation of genomic DNA for DNA hybridization.

    Science.gov (United States)

    Wang, Xiaofang; Son, Ahjeong

    2013-12-01

    DNA hybridization is an important step for a number of bioassays such as fluorescence in situ hybridization, microarrays, as well as the NanoGene assay. Denaturation and fragmentation of genomic DNA are two critical pretreatments for DNA hybridization. However, no thorough and systematic characterization on denaturation and fragmentation has been carried out for the NanoGene assay so far. In this study, we investigated the denaturation and fragmentation of the bacterial gDNA with physical treatments (i.e., heating and sonication) and chemical treatments (i.e., dimethyl sulfoxide). First of all, a simple approach for indicating the denaturation fraction was developed based on the absorbance difference (i.e., hyperchromic effect) between the double-stranded DNA and single-stranded DNA fragments. Then the denaturation capabilities of the treatments to the gDNA were elucidated, followed by the examination of the possible renaturation over time. The fragmentation of the gDNA by each treatment was also investigated. Based on denaturation efficiency, minimum renaturation tendency, and fragmentation, the sonication method was found to be the best among the six methods. We further demonstrated that the sonication method produced the best result among the treatments examined for the DNA hybridization in the NanoGene assay.

  19. Atomic Clocks Research - An Overview.

    Science.gov (United States)

    1987-08-15

    magnet. Since atomic deflection in an inhomogeneous magnetic field is inversely proportional to the square of the atomic speed, the atomic velocity...purifier and controlled leak; an atomic source (i.e., the dissociator under 39 study); a dipole electromagnetic with pole pieces shaped to produce an...34Relaxation Magnetique d’Atomes de Rubidium sur des Parois Paraffines," J. Phys. (Paris) 24, 379 (1963). 21. S. Wexler, "Deposition of Atomic Beams

  20. Radiation Dosimetry via Automated Fluorescence Microscopy

    Science.gov (United States)

    Castleman, Kenneth R.; Schulze, Mark

    2005-01-01

    A developmental instrument for assessment of radiation-induced damage in human lymphocytes includes an automated fluorescence microscope equipped with a one or more chargecoupled- device (CCD) video camera(s) and circuitry to digitize the video output. The microscope is also equipped with a three-axis translation stage that includes a rotation stage, and a rotary tray that holds as many as thirty specimen slides. The figure depicts one version of the instrument. Once the slides have been prepared and loaded into the tray, the instrument can operate unattended. A computer controls the operation of the stage, tray, and microscope, and processes the digital fluorescence-image data to recognize and count chromosomes that have been broken, presumably by radiation. The design and method of operation of the instrument exploit fluorescence in situ hybridization (FISH) of metaphase chromosome spreads, which is a technique that has been found to be valuable for monitoring the radiation dose to circulating lymphocytes. In the specific FISH protocol used to prepare specimens for this instrument, metaphase lymphocyte cultures are chosen for high mitotic index and highly condensed chromosomes, then several of the largest chromosomes are labeled with three of four differently colored whole-chromosome-staining dyes. The three dyes, which are used both individually and in various combinations, are fluorescein isothiocyanate (FITC), Texas Red (or equivalent), and Cy5 (or equivalent); The fourth dye 4',6-diamidino- 2-phenylindole (DAPI) is used as a counterstain. Under control by the computer, the microscope is automatically focused on the cells and each slide is scanned while the computer analyzes the DAPI-fluorescence images to find the metaphases. Each metaphase field is recentered in the field of view and refocused. Then a four-color image (more precisely, a set of images of the same view in the fluorescent colors of the four dyes) is acquired. By use of pattern

  1. Wave Atom Based Watermarking

    OpenAIRE

    Bukhari, Ijaz; Nuhman-ul-Haq; Hyat, Khizar

    2013-01-01

    Watermarking helps in ensuring originality, ownership and copyrights of a digital image. This paper aims at embedding a Watermark in an image using Wave Atom Transform. Preference of Wave Atoms on other transformations has been due to its sparser expansion, adaptability to the direction of local pattern, and sharp frequency localization. In this scheme, we had tried to spread the watermark in an image so that the information at one place is very small and undetectable. In order to extract the...

  2. Hirshfeld atom refinement.

    Science.gov (United States)

    Capelli, Silvia C; Bürgi, Hans-Beat; Dittrich, Birger; Grabowsky, Simon; Jayatilaka, Dylan

    2014-09-01

    Hirshfeld atom refinement (HAR) is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly-l-Ala measured at 12, 50, 100, 150, 220 and 295 K, using Hartree-Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs) are freely refined without constraints or restraints - even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295 K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu's), all other structural parameters agree within less than 2 csu's. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules), the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009 Å for temperatures of 150 K or below; for hydrogen-atom ADPs it is better than 0.006 Å(2) as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements - an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65 Å.

  3. Atoms, molecules & elements

    CERN Document Server

    Graybill, George

    2007-01-01

    Young scientists will be thrilled to explore the invisible world of atoms, molecules and elements. Our resource provides ready-to-use information and activities for remedial students using simplified language and vocabulary. Students will label each part of the atom, learn what compounds are, and explore the patterns in the periodic table of elements to find calcium (Ca), chlorine (Cl), and helium (He) through hands-on activities.

  4. Atomic Bomb Health Benefits

    OpenAIRE

    Luckey, T. D.

    2008-01-01

    Media reports of deaths and devastation produced by atomic bombs convinced people around the world that all ionizing radiation is harmful. This concentrated attention on fear of miniscule doses of radiation. Soon the linear no threshold (LNT) paradigm was converted into laws. Scientifically valid information about the health benefits from low dose irradiation was ignored. Here are studies which show increased health in Japanese survivors of atomic bombs. Parameters include decreased mutation,...

  5. Atomic interferometry; Interferometrie atomique

    Energy Technology Data Exchange (ETDEWEB)

    Baudon, J.; Robert, J. [Paris-13 Univ., 93 - Saint-Denis (France)

    2004-07-01

    Since the theoretical works of L. De Broglie (1924) and the famous experiment of Davisson and Germer (1927), we know that a wave is linked with any particle of mass m by the relation {lambda} = h/(mv), where {lambda} is the wavelength, v the particle velocity and h is the Planck constant. The basic principle of the interferometry of any material particle, atom, molecule or aggregate is simple: using a simple incident wave, several mutually consistent waves (with well-defined relative phases) are generated and controllable phase-shifts are introduced between them in order to generate a wave which is the sum of the previous waves. An interference figure is obtained which consists in a succession of dark and bright fringes. The atomic interferometry is based on the same principle but involves different techniques, different wave equations, but also different beams, sources and correlations which are described in this book. Because of the small possible wavelengths and the wide range of possible atomic interactions, atomic interferometers can be used in many domains from the sub-micron lithography to the construction of sensors like: inertial sensors, gravity-meters, accelerometers, gyro-meters etc. The first chapter is a preliminary study of the space and time diffraction of atoms. The next chapters is devoted to the description of slit, light separation and polarization interferometers, and the last chapter treats of the properties of Bose-Einstein condensates which are interesting in atomic interferometry. (J.S.)

  6. Atomic bomb and leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Ichimaru, M.; Tomonaga, M.; Amenomori, T.; Matsuo, T. (Nagasaki Univ. (Japan). School of Medicine)

    1991-12-01

    Characteristic features of the leukemia among atomic bomb survivors were studied. Dose estimates of atomic bomb radiation were based on T65D, but the new dosimetry system DS86 was used for some analyses. The ratio of a single leukemia type to all leukemias was highest for chronic myelogenous leukemia (CML) in Hiroshima, and the occurrence of CML was thought to be most characteristic to atomic bomb radiation induced leukemia. The threshold of CML occurrence in Hiroshima is likely to be between 0.5{approx}0.09 Gy. However, the threshold of acute leukemia appears to be nearly 1 Gy. In the distribution of acute myeloid leukemia (AML) subtypes by French-American-British classification, there was no M3 case in 1 Gy or more group, although several atypical AML cases of survivors were observed. Although aplastic anemia has not increased as a late effect of the atomic bomb radiation exposure, many atypical leukemia or other myeloproliferative diseases who had been diagnosed as aplastic anemia or its related diseases have been experienced among atomic bomb survivors. Chromosome study was conducted using colony forming cells induced by hemopoietic stem cells of peripheral blood of proximal survivors. Same chromosome aberrations were observed in colony forming cells and peripheral T-cells in several atomic bomb survivors. (author).

  7. Circular dichroism spectroscopy of fluorescent proteins

    NARCIS (Netherlands)

    Visser, N.V.; Hink, M.A.; Borst, J.W.; Krogt, van der G.N.M.; Visser, A.J.W.G.

    2002-01-01

    Circular dichroism (CD) spectra have been obtained from several variants of green fluorescent protein: blue fluorescent protein (BFP), enhanced cyan fluorescent protein (CFP), enhanced green fluorescent protein (GFP), enhanced yellow fluorescent protein (YFP), all from Aequorea victoria, and the red

  8. The use of Visual Implant Fluorescent Elastomer (VIE for marking Phyllopezus pollicaris lizards (Squamata: Phyllodactylidae

    Directory of Open Access Journals (Sweden)

    Paulo Ragner Silva de Freitas

    2013-11-01

    Full Text Available This study reports the use of Visible Implant Fluorescent Elastomer (VIE and its efficiency in marking Phyllopezus pollicaris lizards from an area of caatinga in northeastern Brazil. The marking procedure of individuals was conducted from April to September 2012. Forty individuals were marked in the dorsal region with fluorescent colors (red, yellow, green and orange. Twenty lizards were recaptured and showed good retention of the elastomer. Only two specimens presented fragmented marks. The results showed that the use of VIE for tagging and recapture was efficient because of the high retention rate in the individuals recaptured and low fragmentation rate of the marks.

  9. Using Terminal Restriction Fragment Length Polymorphism (T-RFLP) Analysis to Assess Microbial Community Structure in Compost Systems

    Science.gov (United States)

    Tiquia, Sonia M.

    Terminal restriction fragment length polymorphism (T-RFLP) analysis of PCR-amplified genes is a widely used fingerprinting technique in composting systems. This analysis is based on the restriction endonuclease digestion of fluorescently end-labeled PCR products. The digested product is mixed with a DNA size standard, itself labeled with a distinct fluorescent dye, and the fragments are then separated by capillary or gel electrophoresis using an automated sequencer. Upon analysis, only the terminal end-labeled restriction fragments are detected. An electropherogram is produced, which shows a profile of compost microbial community as a series of peaks of varying height. This technique has also been effectively used in the exploration of complex microbial environments and in the study of bacterial, archaeal, and eukaryal populations in natural habitats.

  10. Decoupling habitat fragmentation from habitat loss: butterfly species mobility obscures fragmentation effects in a naturally fragmented landscape of lake islands.

    Science.gov (United States)

    MacDonald, Zachary G; Anderson, Iraleigh D; Acorn, John H; Nielsen, Scott E

    2018-01-01

    Since the publication of the theory of island biogeography, ecologists have postulated that fragmentation of continuous habitat presents a prominent threat to species diversity. However, negative fragmentation effects may be artifacts; the result of species diversity declining with habitat loss, and habitat loss correlating positively with degree of fragmentation. In this study, we used butterfly assemblages on islands of Lake of the Woods, Ontario, Canada to decouple habitat fragmentation from habitat loss and test two competing hypotheses: (1) the island effect hypothesis, which predicts that decreasing fragment size and increasing fragment isolation reduces species diversity beyond the effects of habitat loss, and (2) the habitat amount hypothesis, which negates fragmentation effects and predicts that only total habitat area determines the diversity of species persisting on fragmented landscapes. Using eight independent size classes of islands (ranging from 0.1 to 8.0 ha) that varied in number of islands while holding total area constant, species diversity comparisons, species accumulation curves, and species-area relationship extrapolations demonstrated that smaller insular habitats contained at least as many butterfly species as continuous habitat. However, when highly mobile species occurring on islands without their larval food plants were excluded from analyses, island effects on potentially reproducing species became apparent. Similarily, generalized linear models suggested that effects of island isolation and vascular plant richness on insular butterfly richness were confounded by species of high mobility. We conclude that inter-fragment movements of highly mobile species may obscure important fragmentation effects on potentially reproducing populations, questioning support for the habitat amount hypothesis.

  11. The soluble urokinase plasminogen activator receptor and its fragments in venous ulcers

    DEFF Research Database (Denmark)

    Ahmad, Anwar; Saha, Prakash; Evans, Colin

    2015-01-01

    functions that include chemotaxis, adhesion, and proliferation, which also have a role in wound healing. The aim of this study was to determine whether suPAR and its cleaved fragments are present in venous ulcers and whether their levels are associated with healing. METHODS: Ulcer exudates were collected...... from patients with venous leg ulcers (n = 30). Healing was defined as complete re-epithelialization within 6 months of compression therapy. Time-resolved fluorescence immunoassays were validated for quantification of suPAR and its fragments in ulcer exudates. The effect of exudates on keratinocyte...... with nonhealers (n = 21). Exudate from healing ulcers stimulated keratinocyte migration (P = .02), whereas depletion of suPAR from exudates resulted in cell apoptosis. CONCLUSIONS: We conclude that suPAR and its fragments are present in the environs of venous ulcers and may act as indicators of the propensity...

  12. Atomic Force Microscopy

    Indian Academy of Sciences (India)

    microscopes, but AFM can be used to image four molecules of p53 bound to a small fragment of DNA. Here we can also ..... another useful feature to the AFM systems. .... tion: AFM has been used extensively to understand the structure– function organization of different sub-nuclear organelle. Nucleus. Figure 7a. Eukaryotic.

  13. Multicolor-based discrimination of 21 short tandem repeats and amelogenin using four fluorescent universal primers.

    Science.gov (United States)

    Asari, Masaru; Okuda, Katsuhiro; Hoshina, Chisato; Omura, Tomohiro; Tasaki, Yoshikazu; Shiono, Hiroshi; Matsubara, Kazuo; Shimizu, Keiko

    2016-02-01

    The aim of this study was to develop a cost-effective genotyping method using high-quality DNA for human identification. A total of 21 short tandem repeats (STRs) and amelogenin were selected, and fluorescent fragments at 22 loci were simultaneously amplified in a single-tube reaction using locus-specific primers with 24-base universal tails and four fluorescent universal primers. Several nucleotide substitutions in universal tails and fluorescent universal primers enabled the detection of specific fluorescent fragments from the 22 loci. Multiplex polymerase chain reaction (PCR) produced intense FAM-, VIC-, NED-, and PET-labeled fragments ranging from 90 to 400 bp, and these fragments were discriminated using standard capillary electrophoretic analysis. The selected 22 loci were also analyzed using two commercial kits (the AmpFLSTR Identifiler Kit and the PowerPlex ESX 17 System), and results for two loci (D19S433 and D16S539) were discordant between these kits due to mutations at the primer binding sites. All genotypes from the 100 samples were determined using 2.5 ng of DNA by our method, and the expected alleles were completely recovered. Multiplex 22-locus genotyping using four fluorescent universal primers effectively reduces the costs to less than 20% of genotyping using commercial kits, and our method would be useful to detect silent alleles from commercial kit analysis. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Photodesorption of Na atoms from rough Na surfaces

    DEFF Research Database (Denmark)

    Balzer, Frank; Gerlach, R.; Manson, J.R.

    1997-01-01

    We investigate the desorption of Na atoms from large Na clusters deposited on dielectric surfaces. High-resolution translational energy distributions of the desorbing atoms are determined by three independent methods, two-photon laser-induced fluorescence, as well as single-photon and resonance......-enhanced two-photon ionization techniques. Upon variation of surface temperature and for different substrates (mica vs lithium fluoride) clear non-Maxwellian time-of-flight distributions are observed with a cos θ angular dependence and most probable kinetic energies below that expected of atoms desorbing from...... atoms are scattered by surface vibrations. Recent experiments providing time constants for the decay of the optical excitations in the clusters support this model. The excellent agreement between experiment and theory indicates the importance of both absorption of the laser photons via direct excitation...

  15. Pulsed metastable atom source for low vapour-pressure metals

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Urena, A.; Verdasco Costales, E. (Universidad Complutense de Madrid (Spain). Facultad de Quimica); Saez Rabanos, V. (Universidad Politecnica de Madrid (Spain). Escuela Tecnica Superior de Ingenieros Industriales)

    1990-03-01

    The basic design and most relevant experimental conditions of a pulsed metastable atomic-beam oven are described. The stainless steel oven is suitable for vaporising metals and salts up to around 1400 K producing intense beams of metastable alkaline-earth atoms when pulsed or continuous wave low voltage discharges are used. Several applications using atomic calcium in its {sup 3}P and {sup 1}D electronic state are reported. The beam characterisation and discharge efficiency have been measured by time-of-flight or laser-induced fluorescence techniques. In addition, a method of changing the metastable n{sup 3}P/n{sup 1}D ratio, by raising the oven temperature, is described which looks very promising for the study of electronic selectivity in reactive collision processes. Finally several spectroscopic applications for atomic and molecular beam determinations are reported. (author).

  16. FRAGMENTATION OF CONTINENTAL UNITES STATES FORESTS

    Science.gov (United States)

    We report a multiple-scale analysis of forest fragmentation based on 30-m land-cover maps for the conterminous United States. Each 0.09-ha unit of forest was classified according to fragmentation indices measured within the surrounding landscape, for five landscape sizes from 2....

  17. Generalized Fragmentation Functions for Fractal Jet Observables

    NARCIS (Netherlands)

    Elder, B.T.; Procura, M.; Thaler, J.; Waalewijn, W.J.; Zhou, K.

    We introduce a broad class of fractal jet observables that recursively probe the collective properties of hadrons produced in jet fragmentation. To describe these collinear-unsafe observables, we generalize the formalism of fragmentation functions, which are important objects in QCD for calculating

  18. INTERMITTENCY, A TEST FOR STRING FRAGMENTATION PROCESSES

    NARCIS (Netherlands)

    SCHOLTEN, O

    The Artru-Mennessier and the string fragmentation procedure as implemented in the code VENUS have been compared. The two fragmentation prescriptions predict a similar rapidity spectrum including its energy dependence and event multiplicities, but give rise to very different intermittency results.

  19. Fragmentation of eastern United States forest types

    Science.gov (United States)

    Kurt H. Riitters; John W. Coulston

    2013-01-01

    Fragmentation is a continuing threat to the sustainability of forests in the Eastern United States, where land use changes supporting a growing human population are the primary driver of forest fragmentation (Stein and others 2009). While once mostly forested, approximately 40 percent of the original forest area has been converted to other land uses, and most of the...

  20. Pollen and gene flow in fragmented habitats

    NARCIS (Netherlands)

    Kwak, Manja M.; Velterop, Odilia; van Andel, Jelte

    . Habitat fragmentation affects both plants and pollinators. Habitat fragmentation leads to changes in species richness, population number and size, density, and shape, thus to changes in the spatial arrangement of flowers. These changes influence the amount of food for flower-visiting insects and

  1. Evaluation of effect of selected trace elements on dynamics of sperm dna fragmentation

    Directory of Open Access Journals (Sweden)

    Artur Wdowiak

    2015-12-01

    Full Text Available Introduction: Lead and cadmium can lead to negative effects on sperm chromatin DNA integrity. Copper, zinc and selenium are essential components of many enzymes which are important for reproduction. The aim of this research was to evaluate the influence of lead, cadmium, zinc, copper and selenium on the dynamics of semen DNA fragmentation.Material and methods: The present study concerned 85 fertile and 131 infertile men aged 25-35. DNA fragmentation in the samples was determined after 3 h, 6 h and 12 h. The Pb, Cd, Cu, Zn, and Se measurements were performed by the electrothermal-atomic absorption spectrometry method.Results: We found that sperm DNA fragmentation was a dynamic process which was intensified with an increase in the level of lead in seminal plasma. The levels of lead and cadmium were higher in seminal plasma of infertile men, compared to fertile men. The levels of zinc, copper and selenium in seminal plasma were higher in men with proven fertility, compared to infertile men, and did not exert a significant effect on the dynamics of sperm DNA fragmentation. The level of cadmium had no significant effect on intensification of sperm DNA fragmentation in time.Discussion: Reports in the literature which concern the effect of trace elements on human reproduction are equivocal. The present study confirmed an unfavourable effect, especially that of lead, on the dynamics of sperm DNA fragmentation; however, these studies need to be expanded and continued in the future.

  2. Classical molecular dynamics simulations of fusion and fragmentation in fullerene-fullerene collisions

    Science.gov (United States)

    Verkhovtsev, Alexey; Korol, Andrei V.; Solovyov, Andrey V.

    2017-08-01

    We present the results of classical molecular dynamics simulations of collision-induced fusion and fragmentation of C60 fullerenes, performed by means of the MBN Explorer software package. The simulations provide information on structural differences of the fused compound depending on kinematics of the collision process. The analysis of fragmentation dynamics at different initial conditions shows that the size distributions of produced molecular fragments are peaked for dimers, which is in agreement with a well-established mechanism of C60 fragmentation via preferential C2 emission.Atomic trajectories of the colliding particles are analyzed and different fragmentation patterns are observed and discussed. On the basis of the performed simulations, characteristic time of C2 emission is estimated as a function of collision energy.The results are compared with experimental time-of-flight distributions of molecular fragments and with earlier theoretical studies. Considering the widely explored case study of C60-C60 collisions, we demonstrate broad capabilities of the MBN Explorer software, which can be utilized for studying collisions of a broad variety of nanoscale and biomolecular systems by means of classical molecular dynamics.

  3. Long-term effects of fragmentation and fragment properties on bird species richness in Hawaiian forests

    Science.gov (United States)

    David J. Flaspohler; Christian P. Giardina; Gregory P. Asner; Patrick Hart; Jonathan Price; Cassie Ka’apu Lyons; Xeronimo. Castaneda

    2010-01-01

    Forest fragmentation is a common disturbance affecting biological diversity, yet the impacts of fragmentation on many forest processes remain poorly understood. Forest restoration is likely to be more successful when it proceeds with an understanding of how native and exotic vertebrates utilize forest patches of different size. We used a system of forest fragments...

  4. Simulation analysis of effects of single fragment size on air-blast wave and fragment propagation

    Directory of Open Access Journals (Sweden)

    ZHENG Hongwei

    2017-12-01

    Full Text Available [Objectives] This paper involves the propagation and attenuation of the velocity and energy of air-blast waves and high-velocity fragments while taking their combined effects into account.[Methods] With ANSYS/LS-DYNA software, a simulation model of a columnar TNT air blast is built with prefabricated fragments affixed to its end. When the total quality of fragments is constant, the effects of a single fragment's size on the propagation of the air-blast wave and fragments are studied by changing the size of the single fragment.[Results] The results show that fragments greatly reduce the intensity and velocity of a shockwave, and block the air-blast waves behind them. When the total quality of the fragments remains constant, the effects of single fragment size on blast shockwave propagation characteristics show little difference. The smaller the single fragment, the more kinetic energy the fragments will have and the faster that energy will dissipate.[Conclusions] As a result, more attention should be paid to the combined effects of air-blast waves and high-velocity fragments. Such research can provide reference points for the deeper study of blast loads and their interaction.

  5. Effects of external fields, dimension and polarization on the resonance fluorescence of quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Vaseghi, B., E-mail: vaseghi@mail.yu.ac.ir; Razavi, S.M.

    2017-02-01

    In this paper simultaneous effects of external electric and magnetic fields, dimension and polarization on the resonance fluorescence spectrum and photon statistics of a spherical quantum dot with parabolic confinement are investigated. With special attention to the optical scattering processes resonance fluorescence spectrum and second-order correlation function are calculated and plotted for different external parameters. Our results show the occurrence of resonance fluorescence similar to atomic systems and considerable effects of external fields, quantum confinement and light polarization on the resonance fluorescence spectrum and second-order correlation function in the quantum dot systems. The existence of Mollow triplets and photon antibunching are strongly depend on these external agents.

  6. Highly luminescent N-doped carbon quantum dots as an effective multifunctional fluorescence sensing platform.

    Science.gov (United States)

    Qian, Zhaosheng; Ma, Juanjuan; Shan, Xiaoyue; Feng, Hui; Shao, Linxiang; Chen, Jianrong

    2014-02-17

    The doping of carbon quantum dots with nitrogen provides a promising direction to improve fluorescence performance and broaden their applications in sensing systems. Herein we report a one-pot solvothermal synthesis of N-doped carbon quantum dots (NCQDs) and the synthesis of a series of NCQDs with different nitrogen contents. The as-prepared NCQDs were compared with carbon quantum dots (CQDs); the introduction of nitrogen atoms largely increased the quantum yield of NCQDs and highest emission efficiency is up to 36.3 %. The fluorescence enhancement may originate from more polyaromatic structures induced by incorporated nitrogen atoms and protonation of nitrogen atoms on dots. It was found that NCQDs can act as a multifunctional fluorescence sensing platform because they can be used to detect pH values, Ag(I), and Fe(III) in aqueous solution. The fluorescence intensity of NCQDs is inversely proportional to pH values across a broad range from 5.0 to 13.5, which indicates that NCQDs can be devised as an effective pH indicator. Selective detection of Ag(I) and Fe(III) was achieved based on their distinctive fluorescence influence because Ag(I) can significantly enhance the fluorescence whereas Fe(III) can greatly quench the fluorescence. The quantitative determination of Ag(I) can be accomplished with NCQDs by using the linear relationship between fluorescence intensity of NCQDs and concentration of Ag(I). The sensitive detection of H2O2 was developed by taking advantage of the distinct quenching ability of Fe(III) and Fe(II) toward the fluorescence of NCQDs. Cellular toxicity test showed NCQDs still retain low toxicity to cells despite the introduction of a great deal of nitrogen atoms. Moreover, bioimaging experiments demonstrated that NCQDs have stronger resistance to photobleaching than CQDs and more excellent fluorescence labeling performance. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Diquark Fragmentation Contribution in Λ b Production

    Science.gov (United States)

    Osati, T.; Movlanaei, M.

    2017-05-01

    In the framework of the quark-diquark model of baryons, Λ b can be considered as b constituent quark an ud constituent diquark. In this study, we investigate the effect ud scalar diquark fragmentation into Λ b , therefor we calculate frgmentation functions of b quark and ud diquark into Λ b baryon through the use of perturbative QCD. In the next stage, throuth the use of the obtained fragmentation functions, we calculate the total fragmentation probabilities and average fragmentation parameters for b→Λ b and u d→Λ b . Finally, the inclusive cross section of Λ b baryon in electron-positron annihilation in ALEPH experiment is calculated with regard to ud diquark fragmentation contribution.

  8. Chimeric recombinant antibody fragments in cardiac troponin I immunoassay.

    Science.gov (United States)

    Hyytiä, Heidi; Heikkilä, Taina; Brockmann, Eeva-Christine; Kekki, Henna; Hedberg, Pirjo; Puolakanaho, Tarja; Lövgren, Timo; Pettersson, Kim

    2015-03-01

    To introduce a novel nanoparticle-based immunoassay for cardiac troponin I (cTnI) utilizing chimeric antibody fragments and to demonstrate that removal of antibody Fc-part and antibody chimerization decrease matrix related interferences. A sandwich-type immunoassay for cTnI based on recombinant chimeric (mouse variable/human constant) antigen binding (cFab) antibodies and intrinsically fluorescent nanoparticles was developed. To test whether using chimeric antibody fragments helps to avoid matrix related interferences, samples (n=39) with known amounts of triglycerides, bilirubin, rheumatoid factor (RF) or human anti-mouse antibodies (HAMAs) were measured with the novel assay, along with a previously published nanoparticle-based research assay with the same antibody epitopes. The limit of detection (LoD) was 3.30ng/L. Within-laboratory precision for 29ng/L and 2819ng/L cTnI were 13.7% and 15.9%, respectively. Regression analysis with Siemens ADVIA Centaur® yielded a slope (95% confidence intervals) of 0.18 (0.17-1.19) and a y-intercept of 1.94 (-1.28-3.91) ng/L. When compared to a previously published nanoparticle-based assay, the novel assay showed substantially reduced interference in the tested interference prone samples, 15.4 vs. 51.3%. A rheumatoid factor containing sample was decreased from 241ng/L to fragments enabled the development of a sensitive (LoD=3.3ng/L) immunoassay for the detection of cTnI and decreased matrix related interferences, thus resulting in a lower number of falsely elevated cTnI-values. Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  9. Universal bosonic tetramers of dimer-atom-atom structure

    OpenAIRE

    Deltuva, A.

    2012-01-01

    Unstable four-boson states having an approximate dimer-atom-atom structure are studied using momentum-space integral equations for the four-particle transition operators. For a given Efimov trimer the universal properties of the lowest associated tetramer are determined. The impact of this tetramer on the atom-trimer and dimer-dimer collisions is analyzed. The reliability of the three-body dimer-atom-atom model is studied.

  10. MATERIALS WITH COMPLEX ELECTRONIC/ATOMIC STRUCTURES

    Energy Technology Data Exchange (ETDEWEB)

    D. M. PARKIN; L. CHEN; ET AL

    2000-09-01

    We explored both experimentally and theoretically the behavior of materials at stresses close to their theoretical strength. This involves the preparation of ultra fine scale structures by a variety of fabrication methods. In the past year work has concentrated on wire drawing of in situ composites such as Cu-Ag and Cu-Nb. Materials were also fabricated by melting alloys in glass and drawing them into filaments at high temperatures by a method known as Taylor wire technique. Cu-Ag microwires have been drawn by this technique to produce wires 10 {micro}m in diameter that consist of nanoscale grains of supersaturated solid solution. Organogels formed from novel organic gelators containing cholesterol tethered to squaraine dyes or trans-stilbene derivatives have been studied from several different perspectives. The two types of molecules are active toward several organic liquids, gelling in some cases at w/w percentages as low as 0.1. While relatively robust, acroscopically dry gels are formed in several cases, studies with a variety of probes indicate that much of the solvent may exist in domains that are essentially liquid-like in terms of their microenvironment. The gels have been imaged by atomic force microscopy and conventional and fluorescence microscopy, monitoring both the gelator fluorescence in the case of the stilbene-cholesterol gels and, the fluorescence of solutes dissolved in the solvent. Remarkably, our findings show that several of the gels are composed of similarly appearing fibrous structures visible at the nano-, micro-, and macroscale.

  11. Formaldehyde adsorption on carbon nanotubes fragment by density functional theory

    Science.gov (United States)

    Chen, D.; Yuan, Yong J.

    2017-07-01

    The interaction between formaldehyde (HCOH) and pristine single-walled carbon nanotube (SWCNT) fragment was investigated by density functional theory (DFT) to evaluate the detection of HCOH. The simulation results demonstrated less adsorption on surface of SWCNT and doped CNTs, while a HCOH molecule tended to be chemisorbed to the C atom located on SWCNT’s edge positions with larger binding energy of 1.742 eV and smaller binding distance of 1.351 Å. Furthermore, charge transfer and density of states study indicated that the electronic properties changed evidently in the most stable HCOH-SWCNT system, and were mainly around the Fermi level. More importantly, the adsorption of HCOH affected the electronic conductance of SWCNT. It is expected that the results could provide a useful theoretical guidance for the investigation of molecular films interface bonding and design of HCOH sensing devices.

  12. N-Terminal Fragments of Huntingtin Longer than Residue 170 form Visible Aggregates Independently to Polyglutamine Expansion.

    Science.gov (United States)

    Chen, Moore Z; Mok, Sue-Ann; Ormsby, Angelique R; Muchowski, Paul J; Hatters, Danny M

    2017-01-01

    A hallmark of Huntington's disease is the progressive aggregation of full length and N-terminal fragments of polyglutamine (polyQ)-expanded Huntingtin (Htt) into intracellular inclusions. The production of N-terminal fragments appears important for enabling pathology and aggregation; and hence the direct expression of a variety of N-terminal fragments are commonly used to model HD in animal and cellular models. It remains unclear how the length of the N-terminal fragments relates to polyQ - mediated aggregation. We investigated the fundamental intracellular aggregation process of eight different-length N-terminal fragments of Htt in both short (25Q) and long polyQ (97Q). N-terminal fragments were fused to fluorescent proteins and transiently expressed in mammalian cell culture models. These included the classic exon 1 fragment (90 amino acids) and longer forms of 105, 117, 171, 513, 536, 552, and 586 amino acids based on wild-type Htt (of 23Q) sequence length nomenclature. N-terminal fragments of less than 171 amino acids only formed inclusions in polyQ-expanded form. By contrast the longer fragments formed inclusions irrespective of Q-length, with Q-length playing a negligible role in extent of aggregation. The inclusions could be classified into 3 distinct morphological categories. One type (Type A) was universally associated with polyQ expansions whereas the other two types (Types B and C) formed independently of polyQ length expansion. PolyQ-expansion was only required for fragments of less than 171 amino acids to aggregate. Longer fragments aggregated predominately through a non-polyQ mechanism, involving at least one, and probably more distinct clustering mechanisms.

  13. Concentrators using fluorescent substances

    Energy Technology Data Exchange (ETDEWEB)

    Hayashibara, M.; Tsukamoto, M. (Hitachi Seisakusho K.K., Tokyo (Japan))

    1990-01-01

    In luminescent concentrators - plates of polymethylmethacrylate (PMMA) or other transparent material with a fluorescent compound dispersed within them - incident light is trapped and concentrated by internal reflection, and shifted to a longer wavelength, as it interacts with fluorescent particles. Experience with the use of luminescent concentrators for electricity generation in conjunction with solar cells, in solar heaters, in amplifiers for light intensity, in long-wave converters and in display panels is discussed. Solar energy conversion efficiencies of 4-5% have been obtained in generating systems combining concentrators containing Fluorol 555 or Rhodamin 6G with GaAs solar cells. (author).

  14. Smartphone fluorescence spectroscopy

    Science.gov (United States)

    Yu, Hojoeng; Tan, Yafang; Cunningham, Brian T.

    2014-03-01

    We demonstrate the first use of smartphone spectrophotometry for readout of fluorescence-based biological assays. We evaluated the smartphone fluorimeter in the context of a fluorescent molecular beacon (MB) assay for detection of a specific nucleic acid sequences in a liquid test sample. The capability of distinguishing a one-point mismatch is also demonstrated by detecting single-base mutation in target nucleic acids. Our approach offers a route towards portable biomolecular assays for viral/bacterial pathogens, disease biomarkers, and toxins.

  15. Smartphone fluorescence spectroscopy.

    Science.gov (United States)

    Yu, Hojeong; Tan, Yafang; Cunningham, Brian T

    2014-09-02

    We demonstrate the first use of smartphone spectrophotometry for readout of fluorescence-based biological assays. We evaluated the smartphone fluorimeter in the context of a fluorescent molecular beacon (MB) assay for detection of specific nucleic acid sequences in a liquid test sample and compared performance against a conventional laboratory fluorimeter. The capability of distinguishing a one-point mismatch is also demonstrated by detecting single-base mutation in target nucleic acids. Our approach offers a route toward portable biomolecular assays for viral/bacterial pathogens, disease biomarkers, and toxins.

  16. Exact Solutions of Fragmentation Equations with General Fragmentation Rates and Separable Particles Distribution Kernels

    Directory of Open Access Journals (Sweden)

    S. C. Oukouomi Noutchie

    2014-01-01

    Full Text Available We make use of Laplace transform techniques and the method of characteristics to solve fragmentation equations explicitly. Our result is a breakthrough in the analysis of pure fragmentation equations as this is the first instance where an exact solution is provided for the fragmentation evolution equation with general fragmentation rates. This paper is the key for resolving most of the open problems in fragmentation theory including “shattering” and the sudden appearance of infinitely many particles in some systems with initial finite particles number.

  17. Sampling the Hydrogen Atom

    Directory of Open Access Journals (Sweden)

    Graves N.

    2013-01-01

    Full Text Available A model is proposed for the hydrogen atom in which the electron is an objectively real particle orbiting at very near to light speed. The model is based on the postulate that certain velocity terms associated with orbiting bodies can be considered as being af- fected by relativity. This leads to a model for the atom in which the stable electron orbits are associated with orbital velocities where Gamma is n /α , leading to the idea that it is Gamma that is quantized and not angular momentum as in the Bohr and other models. The model provides a mechanism which leads to quantization of energy levels within the atom and also provides a simple mechanical explanation for the Fine Struc- ture Constant. The mechanism is closely associated with the Sampling theorem and the related phenomenon of aliasing developed in the mid-20th century by engineers at Bell labs.

  18. Cold Rydberg Atoms Trapped in a CO2 Optical Lattice

    Science.gov (United States)

    2012-09-03

    Dipole trap chamber, showing the MOT region and the ion time of flight region (in front of the MCP detector ); b) Fluorescence image of atoms in our CO2...using the pulsed field ionization technique (PFI). The ions, formed either in a MOT or a dipole trap, are image onto a MCP detector and a phosphorus...have installed an electron detector and an ion detector ; the later will be able to obtain images of the atoms in the dipole trap. Recently, we have

  19. Atomic Force Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Day, R.D.; Russell, P.E.

    1988-12-01

    The Atomic Force Microscope (AFM) is a recently developed instrument that has achieved atomic resolution imaging of both conducting and non- conducting surfaces. Because the AFM is in the early stages of development, and because of the difficulty of building the instrument, it is currently in use in fewer than ten laboratories worldwide. It promises to be a valuable tool for obtaining information about engineering surfaces and aiding the .study of precision fabrication processes. This paper gives an overview of AFM technology and presents plans to build an instrument designed to look at engineering surfaces.

  20. Hirshfeld atom refinement

    Directory of Open Access Journals (Sweden)

    Silvia C. Capelli

    2014-09-01

    Full Text Available Hirshfeld atom refinement (HAR is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly–l-Ala measured at 12, 50, 100, 150, 220 and 295 K, using Hartree–Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs are freely refined without constraints or restraints – even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295 K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu's, all other structural parameters agree within less than 2 csu's. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules, the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009 Å for temperatures of 150 K or below; for hydrogen-atom ADPs it is better than 0.006 Å2 as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements – an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65 Å.

  1. Optically pumped atoms

    CERN Document Server

    Happer, William; Walker, Thad

    2010-01-01

    Covering the most important knowledge on optical pumping of atoms, this ready reference is backed by numerous examples of modelling computation for optical pumped systems. The authors show for the first time that modern scientific computing software makes it practical to analyze the full, multilevel system of optically pumped atoms. To make the discussion less abstract, the authors have illustrated key points with sections of MATLAB codes. To make most effective use of contemporary mathematical software, it is especially useful to analyze optical pumping situations in the Liouville spa

  2. Atoms in Agriculture

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, Thomas S. [University of Tennessee

    1965-01-01

    Agriculture benefits from the applications of research. Radioactive techniques have been used to study soils, plants, microbes, insects, farm animals, and new ways to use and preserve foodstuffs. Radioactive atoms are not used directly by farmers but are used in research directed by the U. S. Department of Agriculture and Atomic Energy Commission, by the agricultural experiment stations of the various states, and by numerous public and private research institutions. From such research come improved materials and methods which are used on the farm.

  3. From Atoms to Solids

    Science.gov (United States)

    1999-01-31

    Honea. M.L. Homer, J.L. Persson, R.L. Whetten , Chem. atoms Phys. Lett. 171 (1990) 147. [17] M.R. Hoare, Adv. Chem. Phys. 40 (1979) 49. Two types of...Persson, M.E. LaVilla, R.L. tal conditions, the clusters become rigid. Thereafter, Whetten , J. Phys. Chem. 93 (1989) 2869. each newly added atom condenses...106 (1981) 265. M. Broyer, Phys. Rev. A 39 (1989) 6056. [9] W. Ekardt, Ber. Bunsenges. Phys. Chem. 88 (1984) 289. [38] R.L. Whetten , private

  4. Korean atomic bomb victims.

    Science.gov (United States)

    Sasamoto, Yukuo

    2009-01-01

    After colonizing Korea, Japan invaded China, and subsequently initiated the Pacific War against the United States, Britain, and their allies. Towards the end of the war, U.S. warplanes dropped atomic bombs on Hiroshima and Nagasaki, which resulted in a large number of Koreans who lived in Hiroshima and Nagasaki suffering from the effects of the bombs. The objective of this paper is to examine the history of Korea atomic bomb victims who were caught in between the U.S., Japan, the Republic of Korea (South Korea) and the Democratic People's Republic of Korea (North Korea).

  5. Atomic bomb and leukemia

    Energy Technology Data Exchange (ETDEWEB)

    Ichimaru, Michito; Tomonaga, Masao; Amenomori, Tatsuhiko; Matsuo, Tatsuki (Nagasaki Univ. (Japan). School of Medicine)

    1991-03-01

    Characteristic features of leukemia among atomic bomb survivors were studied. The ratio of a single leukemia type to all leukemias was highest for CML in Hiroshima, and the occurrence of CML was thought to be most characteristic for atomic bomb radiation induced leukemia. In the distribution of AML subtypes of FAB classification, there was no M3 cases in 1 Gy or more group, although several atypical AML cases of survivors were observed. Chromosome study was conducted using colony forming cells induced by hemopoietic stem cells of peripheral blood of proximal survivors. Same chromosome aberrations were observed in colony forming cells and peripheral blood of proximal survivors. (author).

  6. Improved chemical shift based fragment selection for CS-Rosetta using Rosetta3 fragment picker

    Energy Technology Data Exchange (ETDEWEB)

    Vernon, Robert [Hospital for Sick Children, Program in Molecular Structure and Function (Canada); Shen, Yang [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States); Baker, David [University of Washington, Department of Biochemistry (United States); Lange, Oliver F., E-mail: oliver.lange@tum.de [Technische Universitaet Muenchen, Department Chemie, Biomolecular NMR and Munich Center for Integrated Protein Science (Germany)

    2013-10-15

    A new fragment picker has been developed for CS-Rosetta that combines beneficial features of the original fragment picker, MFR, used with CS-Rosetta, and the fragment picker, NNMake, that was used for purely sequence based fragment selection in the context of ROSETTA de-novo structure prediction. Additionally, the new fragment picker has reduced sensitivity to outliers and other difficult to match data points rendering the protocol more robust and less likely to introduce bias towards wrong conformations in cases where data is bad, missing or inconclusive. The fragment picker protocol gives significant improvements on 6 of 23 CS-Rosetta targets. An independent benchmark on 39 protein targets, whose NMR data sets were published only after protocol optimization had been finished, also show significantly improved performance for the new fragment picker (van der Schot et al. in J Biomol NMR, 2013)

  7. Dual Fragment Impact of PBX Charges

    Science.gov (United States)

    Haskins, Peter; Briggs, Richard; Leeming, David; White, Nathan; Cheese, Philip; DE&S MoD UK Team; Ordnance Test Solutions Ltd Team

    2017-06-01

    Fragment impact can pose a significant hazard to many systems containing explosives or propellants. Testing for this threat is most commonly carried out using a single fragment. However, it can be argued that an initial fragment strike (or strikes) could sensitise the energetic material to subsequent impacts, which may then lead to a more violent reaction than would have been predicted based upon single fragment studies. To explore this potential hazard we have developed the capability to launch 2 fragments from the same gun at a range of velocities, and achieve impacts on an acceptor charge with good control over the spatial and temporal separation of the strikes. In this paper we will describe in detail the experimental techniques we have used, both to achieve the dual fragment launch and observe the acceptor charge response. In addition, we will describe the results obtained against PBX filled explosive targets; discuss the mechanisms controlling the target response and their significance for vulnerability assessment. Results of these tests have clearly indicated the potential for detonation upon the second strike, at velocities well below those needed for shock initiation by a single fragment.

  8. On Disciplinary Fragmentation and Scientific Progress

    Science.gov (United States)

    Balietti, Stefano; Mäs, Michael; Helbing, Dirk

    2015-01-01

    Why are some scientific disciplines, such as sociology and psychology, more fragmented into conflicting schools of thought than other fields, such as physics and biology? Furthermore, why does high fragmentation tend to coincide with limited scientific progress? We analyzed a formal model where scientists seek to identify the correct answer to a research question. Each scientist is influenced by three forces: (i) signals received from the correct answer to the question; (ii) peer influence; and (iii) noise. We observed the emergence of different macroscopic patterns of collective exploration, and studied how the three forces affect the degree to which disciplines fall apart into divergent fragments, or so-called “schools of thought”. We conducted two simulation experiments where we tested (A) whether the three forces foster or hamper progress, and (B) whether disciplinary fragmentation causally affects scientific progress and vice versa. We found that fragmentation critically limits scientific progress. Strikingly, there is no effect in the opposite causal direction. What is more, our results shows that at the heart of the mechanisms driving scientific progress we find (i) social interactions, and (ii) peer disagreement. In fact, fragmentation is increased and progress limited if the simulated scientists are open to influence only by peers with very similar views, or when within-school diversity is lost. Finally, disciplines where the scientists received strong signals from the correct answer were less fragmented and experienced faster progress. We discuss model’s implications for the design of social institutions fostering interdisciplinarity and participation in science. PMID:25790025

  9. Correlative atomic force microscopy and localization-based super-resolution microscopy: revealing labelling and image reconstruction artefacts.

    Science.gov (United States)

    Monserrate, Aitor; Casado, Santiago; Flors, Cristina

    2014-03-17

    Hybrid microscopy: A correlative microscopy tool that combines in situ super-resolution fluorescence microscopy based on single-molecule localization and atomic force microscopy is presented. Direct comparison with high- resolution topography allows the authors to improve fluorescence labeling and image analysis in super-resolution imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Quantum Fragment Based ab Initio Molecular Dynamics for Proteins.

    Science.gov (United States)

    Liu, Jinfeng; Zhu, Tong; Wang, Xianwei; He, Xiao; Zhang, John Z H

    2015-12-08

    Developing ab initio molecular dynamics (AIMD) methods for practical application in protein dynamics is of significant interest. Due to the large size of biomolecules, applying standard quantum chemical methods to compute energies for dynamic simulation is computationally prohibitive. In this work, a fragment based ab initio molecular dynamics approach is presented for practical application in protein dynamics study. In this approach, the energy and forces of the protein are calculated by a recently developed electrostatically embedded generalized molecular fractionation with conjugate caps (EE-GMFCC) method. For simulation in explicit solvent, mechanical embedding is introduced to treat protein interaction with explicit water molecules. This AIMD approach has been applied to MD simulations of a small benchmark protein Trpcage (with 20 residues and 304 atoms) in both the gas phase and in solution. Comparison to the simulation result using the AMBER force field shows that the AIMD gives a more stable protein structure in the simulation, indicating that quantum chemical energy is more reliable. Importantly, the present fragment-based AIMD simulation captures quantum effects including electrostatic polarization and charge transfer that are missing in standard classical MD simulations. The current approach is linear-scaling, trivially parallel, and applicable to performing the AIMD simulation of proteins with a large size.

  11. Economical Alternatives for High Sensitivity in Atomic Spectrometry Laboratory

    Directory of Open Access Journals (Sweden)

    O. Yavuz Ataman

    2007-12-01

    Full Text Available The most commonly used analytical tools for determination of elements at trace levels are atomic absorption spectrometry (AAS, inductively coupled plasma, optical emission and mass spectrometry (ICP-OES and ICP-MS and atomic fluorescence spectrometry (AFS. Although sensitive plasma techniques are becoming predominant in most of the western laboratories, AAS keeps its importance in developing countries. Simple and inexpensive ways of enhancing sensitivity will be described for laboratories equipped with only a flame AA spectrometer. Although there are many chemical preconcentration procedures to improve sensitivity of flame AAS, only some atom trapping techniques will be included here. One kind of atom trapping device is a slotted quartz tube (SQT used for in situ preconcentration of analyte species followed by a rapid revolatilization cycle to obtain an enhanced signal. These devices provide limits of detection at a level of µg L-1. Another kind of atom trapping involves use of vapor generation technique and quartz or tungsten atom trapping surfaces. The analytical steps consist of the generation of volatile species, usually by hydride formation using NaBH4, trapping these species at the surface of an atom trap held at an optimized temperature and finally re-volatilizing analyte species by rapid heating of trap. These species are transported using a carrier gas to an externally heated quartz tube as commonly used in hydride generation AAS systems; a transient signal is formed and measured. These traps have limits of detection in the order of ng L-1.

  12. Barium transport in the hot spot region of fluorescent lamps

    Science.gov (United States)

    Sigeneger, F.; Rackow, K.; Uhrlandt, D.; Ehlbeck, J.; Lieder, G.

    2010-09-01

    The transport of barium atoms and ions in the vicinity of the hot spot in fluorescent lamps operating at 25 kHz is investigated by a combined experimental and theoretical approach. By laser-induced fluorescence, the particle densities of barium atoms and ions were measured time-resolved at different distances from the spot centre. In addition, the time-dependent cathode fall voltage was measured using an improved band method. The model combines a kinetic part for the electrons with a fluid part for the barium atoms and ions. Both parts are spatially resolved in spherically symmetric geometry. The space-dependent electron Boltzmann equation yields the electron density and the ionization rate coefficient of barium as functions of the cathode fall voltage. These results are used to solve the time-dependent particle balance equations of barium atoms and ions which include the ionization of barium as gain and loss terms, respectively. Good agreement between the measured and calculated particle densities of barium atoms is obtained. A sensitive dependence of the ionization frequency and of the barium particle densities on the cathode fall voltage was found.

  13. Barium transport in the hot spot region of fluorescent lamps

    Energy Technology Data Exchange (ETDEWEB)

    Sigeneger, F; Rackow, K; Uhrlandt, D; Ehlbeck, J; Lieder, G [INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany)

    2010-09-29

    The transport of barium atoms and ions in the vicinity of the hot spot in fluorescent lamps operating at 25 kHz is investigated by a combined experimental and theoretical approach. By laser-induced fluorescence, the particle densities of barium atoms and ions were measured time-resolved at different distances from the spot centre. In addition, the time-dependent cathode fall voltage was measured using an improved band method. The model combines a kinetic part for the electrons with a fluid part for the barium atoms and ions. Both parts are spatially resolved in spherically symmetric geometry. The space-dependent electron Boltzmann equation yields the electron density and the ionization rate coefficient of barium as functions of the cathode fall voltage. These results are used to solve the time-dependent particle balance equations of barium atoms and ions which include the ionization of barium as gain and loss terms, respectively. Good agreement between the measured and calculated particle densities of barium atoms is obtained. A sensitive dependence of the ionization frequency and of the barium particle densities on the cathode fall voltage was found.

  14. Early Reporting of Apoptosis by Real-time Imaging of Cancer Cells Labeled with Green Fluorescent Protein in the Nucleus and Red Fluorescent Protein in the Cytoplasm.

    Science.gov (United States)

    Yang, Meng; Jiang, Ping; Hoffman, Robert M

    2015-05-01

    We previously developed PC-3 human prostate cancer cells expressing red fluorescent protein (RFP) in the cytoplasm and green fluorescent protein (GFP) linked to histone H2B expressed in the nucleus. We demonstrate in the present report the use of these dual-color cells for early detection of apoptosis in the presence of cancer chemotherapy agents. Induction of apoptosis was observed by real-time imaging of cytoplasmic and nuclear size and shape changes and nuclear fragmentation using fluorescence microscopy. Apoptosis was also detected by measuring DNA fragmentation. The cancer chemotherapy agents paclitaxel and vinblastine were used for induction of apoptosis. When the PC-3 dual-color cells were treated with paclitaxel or vinblastine, cytoplasmic and nuclear size and shape changes and nuclear fragmentation were observed by 24 hours. The paclitaxel-treated PC-3 dual-color cells exhibited ring-like structures formed by the fragmented nuclei, which could be brightly visualized by H2B-GFP fluorescence. Apoptosis was also detected by the dual-color PC-3 cells by 24 hours when treated with vinblastine. However, no nuclear ring-like structures were formed in the PC-3 cells by vinblastine treatment. In contrast, DNA fragmentation could not be observed in PC-3 cells until 48 hours after exposure to paclitaxel. Dual-color PC-3 cells can serve as a simple real-time early reporter of apoptosis and as a screen for novel cancer therapeutics or genotoxic agents. The dual-color cell real-time imaging assay is a more sensitive and earlier reporter for apoptosis than the DNA fragmentation assay. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  15. Fluorescence lifetime based bioassays

    Science.gov (United States)

    Meyer-Almes, Franz-Josef

    2017-12-01

    Fluorescence lifetime (FLT) is a robust intrinsic property and material constant of fluorescent matter. Measuring this important physical indicator has evolved from a laboratory curiosity to a powerful and established technique for a variety of applications in drug discovery, medical diagnostics and basic biological research. This distinct trend was mainly driven by improved and meanwhile affordable laser and detection instrumentation on the one hand, and the development of suitable FLT probes and biological assays on the other. In this process two essential working approaches emerged. The first one is primarily focused on high throughput applications employing biochemical in vitro assays with no requirement for high spatial resolution. The second even more dynamic trend is the significant expansion of assay methods combining highly time and spatially resolved fluorescence data by fluorescence lifetime imaging. The latter approach is currently pursued to enable not only the investigation of immortal tumor cell lines, but also specific tissues or even organs in living animals. This review tries to give an actual overview about the current status of FLT based bioassays and the wide range of application opportunities in biomedical and life science areas. In addition, future trends of FLT technologies will be discussed.

  16. Single atoms on demand for cavity QED experiments

    Energy Technology Data Exchange (ETDEWEB)

    Dotsenko, I.

    2007-09-06

    Cavity quantum electrodynamics (cavity QED) describes electromagnetic fields in a confined space and the radiative properties of atoms in such fields. The simplest example of such system is a single atom interacting with one mode of a high-finesse resonator. Besides observation and exploration of fundamental quantum mechanical effects, this system bears a high potential for applications quantum information science such as, e.g., quantum logic gates, quantum communication and quantum teleportation. In this thesis I present an experiment on the deterministic coupling of a single neutral atom to the mode of a high-finesse optical resonator. In Chapter 1 I describe our basic techniques for trapping and observing single cesium atoms. As a source of single atoms we use a high-gradient magneto-optical trap, which captures the atoms from background gas in a vacuum chamber and cools them down to millikelvin temperatures. The atoms are then transferred without loss into a standing-wave dipole trap, which provides a conservative potential required for experiments on atomic coherence such as quantum information processing and metrology on trapped atoms. Moreover, shifting the standing-wave pattern allows us to deterministically transport the atoms (Chapter 2). In combination with nondestructive fluorescence imaging of individual trapped atoms, this enables us to control their position with submicrometer precision over several millimeters along the dipole trap. The cavity QED system can distinctly display quantum behaviour in the so-called strong coupling regime, i.e., when the coherent atom-cavity coupling rate dominates dissipation in the system. This sets the main requirements on the resonator's properties: small mode volume and high finesse. Chapter 3 is devoted to the manufacturing, assembling, and testing of an ultra-high finesse optical Fabry-Perot resonator, stabilized to the atomic transition. In Chapter 4 I present the transportation of single atoms into the

  17. HETC-3STEP included fragmentation process

    Energy Technology Data Exchange (ETDEWEB)

    Shigyo, Nobuhiro; Iga, Kiminori; Ishibashi, Kenji [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering

    1997-03-01

    High Energy Transport Code (HETC) based on the cascade-evaporation model is modified to calculate the fragmentation cross section. For the cascade process, nucleon-nucleon cross sections are used for collision computation; effective in-medium-corrected cross sections are adopted instead of the original free-nucleon collision. The exciton model is adopted for improvement of backward nucleon-emission cross section for low-energy nucleon-incident events. The fragmentation reaction is incorporated into the original HETC as a subroutine set by the use of the systematics of the reaction. The modified HETC (HETC-3STEP/FRG) reproduces experimental fragment yields to a reasonable degree. (author)

  18. Heart Rate Fragmentation: A Symbolic Dynamical Approach

    Directory of Open Access Journals (Sweden)

    Madalena D. Costa

    2017-11-01

    Full Text Available Background: We recently introduced the concept of heart rate fragmentation along with a set of metrics for its quantification. The term was coined to refer to an increase in the percentage of changes in heart rate acceleration sign, a dynamical marker of a type of anomalous variability. The effort was motivated by the observation that fragmentation, which is consistent with the breakdown of the neuroautonomic-electrophysiologic control system of the sino-atrial node, could confound traditional short-term analysis of heart rate variability.Objective: The objectives of this study were to: (1 introduce a symbolic dynamical approach to the problem of quantifying heart rate fragmentation; (2 evaluate how the distribution of the different dynamical patterns (“words” varied with the participants' age in a group of healthy subjects and patients with coronary artery disease (CAD; and (3 quantify the differences in the fragmentation patterns between the two sample populations.Methods: The symbolic dynamical method employed here was based on a ternary map of the increment NN interval time series and on the analysis of the relative frequency of symbolic sequences (words with a pre-defined set of features. We analyzed annotated, open-access Holter databases of healthy subjects and patients with CAD, provided by the University of Rochester Telemetric and Holter ECG Warehouse (THEW.Results: The degree of fragmentation was significantly higher in older individuals than in their younger counterparts. However, the fragmentation patterns were different in the two sample populations. In healthy subjects, older age was significantly associated with a higher percentage of transitions from acceleration/deceleration to zero acceleration and vice versa (termed “soft” inflection points. In patients with CAD, older age was also significantly associated with higher percentages of frank reversals in heart rate acceleration (transitions from acceleration to

  19. Heart Rate Fragmentation: A Symbolic Dynamical Approach.

    Science.gov (United States)

    Costa, Madalena D; Davis, Roger B; Goldberger, Ary L

    2017-01-01

    Background: We recently introduced the concept of heart rate fragmentation along with a set of metrics for its quantification. The term was coined to refer to an increase in the percentage of changes in heart rate acceleration sign, a dynamical marker of a type of anomalous variability. The effort was motivated by the observation that fragmentation, which is consistent with the breakdown of the neuroautonomic-electrophysiologic control system of the sino-atrial node, could confound traditional short-term analysis of heart rate variability. Objective: The objectives of this study were to: (1) introduce a symbolic dynamical approach to the problem of quantifying heart rate fragmentation; (2) evaluate how the distribution of the different dynamical patterns ("words") varied with the participants' age in a group of healthy subjects and patients with coronary artery disease (CAD); and (3) quantify the differences in the fragmentation patterns between the two sample populations. Methods: The symbolic dynamical method employed here was based on a ternary map of the increment NN interval time series and on the analysis of the relative frequency of symbolic sequences (words) with a pre-defined set of features. We analyzed annotated, open-access Holter databases of healthy subjects and patients with CAD, provided by the University of Rochester Telemetric and Holter ECG Warehouse (THEW). Results: The degree of fragmentation was significantly higher in older individuals than in their younger counterparts. However, the fragmentation patterns were different in the two sample populations. In healthy subjects, older age was significantly associated with a higher percentage of transitions from acceleration/deceleration to zero acceleration and vice versa (termed "soft" inflection points). In patients with CAD, older age was also significantly associated with higher percentages of frank reversals in heart rate acceleration (transitions from acceleration to deceleration and vice

  20. Composite Overwrap Fragmentation Observations, Concerns, and Recommendations

    Science.gov (United States)

    Bangham, Mike; Hovater, Mary

    2017-01-01

    A series of test activities has raised some concerns about the generation of orbital debris caused by failures of composite overwrapped pressure vessels (COPVs). These tests have indicated that a large number of composite fragments can be produced by either pressure burst failures or by high-speed impacts. A review of prior high-speed tests with COPV indicates that other tests have produced large numbers of composite fragments. As was the case with the test referenced here, the tests tended to produce a large number of small composite fragments with relatively low velocities induced by the impact and or gas expansion.