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Sample records for nuclear polarization applied

  1. Optimizing dissolution dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Bornet, Aurélien; Jannin, Sami

    2016-03-01

    This article is a short review of some of our recent developments in dissolution dynamic nuclear polarization (d-DNP). We present the basic principles of d-DNP, and motivate our choice to step away from conventional approaches. We then introduce a modified d-DNP recipe that can be summed up as follows: Using broad line polarizing agents to efficiently polarize 1H spins. Increasing the magnetic field to 6.7 T and above. Applying microwave frequency modulation. Applying 1H-13C cross polarization. Transferring hyperpolarized solution through a magnetic tunnel.

  2. Cross-polarization for dissolution dynamic nuclear polarization.

    PubMed

    Batel, Michael; Däpp, Alexander; Hunkeler, Andreas; Meier, Beat H; Kozerke, Sebastian; Ernst, Matthias

    2014-10-21

    Dynamic nuclear polarization (DNP) in combination with subsequent dissolution of the sample allows the detection of low-γ nuclei in the solution state with a signal gain of up to tens of thousand times compared to experiments starting from Boltzmann conditions. The long polarization build-up times of typically more than one hour are a drawback of this technique. The combination of dissolution DNP with cross-polarization (CP) in the solid state was shown to have the potential to overcome this disadvantage. In this article we discuss the cross-polarization step under dissolution DNP conditions in more detail. We show that adiabatic half-passage pulses allow us to enhance the CP efficiency in power-limited DNP probes. As a low-power alternative to Hartmann-Hahn CP we also demonstrate the applicability of frequency-swept de- and re-magnetization pulses for polarization transfer via dipolar order. We investigate the implications and restrictions of the common solid-state DNP mechanisms to the DNP-CP technique and apply a spin-thermodynamic model based on the thermal-mixing mechanism. The model allows us to investigate the dynamics of the polarization levels in a system with two nuclear Zeeman reservoirs and explains the enhanced DNP efficiency upon solvent deuteration within a spin-thermodynamic picture. PMID:25182534

  3. Polarized nuclear target based on parahydrogen induced polarization

    NASA Astrophysics Data System (ADS)

    Budker, D.; Ledbetter, M. P.; Appelt, S.; Bouchard, L. S.; Wojtsekhowski, B.

    2012-12-01

    We discuss a novel concept of a polarized nuclear target for accelerator fixed-target scattering experiments, which is based on parahydrogen induced polarization (PHIP). One may be able to reach a 33% free-proton polarization in the ethane molecule. The potential advantages of such a target include operation at zero magnetic field, fast (˜100 Hz) polarization oscillation (akin to polarization reversal), and operation with large intensity of an electron beam.

  4. Polarized nuclear target based on parahydrogen induced polarization

    SciTech Connect

    D. Budker, M.P. Ledbetter, S. Appelt, L.S. Bouchard, B. Wojtsekhowski

    2012-12-01

    We discuss a novel concept of a polarized nuclear target for accelerator fixed-target scattering experiments, which is based on parahydrogen induced polarization (PHIP). One may be able to reach a 33% free-proton polarization in the ethane molecule. The potential advantages of such a target include operation at zero magnetic field, fast ({approx}100 HZ) polarization oscillation (akin to polarization reversal), and operation with large intensity of an electron beam.

  5. THz Dynamic Nuclear Polarization NMR

    PubMed Central

    Nanni, Emilio A.; Barnes, Alexander B.; Griffin, Robert G.; Temkin, Richard J.

    2013-01-01

    Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) spectroscopy by using high frequency microwaves to transfer the polarization of the electrons to the nuclear spins. The enhancement in NMR sensitivity can amount to a factor of well above 100, enabling faster data acquisition and greatly improved NMR measurements. With the increasing magnetic fields (up to 23 T) used in NMR research, the required frequency for DNP falls into the THz band (140–600 GHz). Gyrotrons have been developed to meet the demanding specifications for DNP NMR, including power levels of tens of watts; frequency stability of a few megahertz; and power stability of 1% over runs that last for several days to weeks. Continuous gyrotron frequency tuning of over 1 GHz has also been demonstrated. The complete DNP NMR system must include a low loss transmission line; an optimized antenna; and a holder for efficient coupling of the THz radiation to the sample. This paper describes the DNP NMR process and illustrates the THz systems needed for this demanding spectroscopic application. THz DNP NMR is a rapidly developing, exciting area of THz science and technology. PMID:24639915

  6. Dynamic nuclear polarization from current-induced electron spin polarization in n-InGaAs

    NASA Astrophysics Data System (ADS)

    Trowbridge, Christopher; Norman, Benjamin; Kato, Yuichiro; Awschalom, David; Sih, Vanessa

    2014-03-01

    Control of the nuclear spin system could prove useful for applications in spintronics or spin-based quantum computation for intermediate term data storage and for the suppression of electron spin dephasing resulting from hyperfine coupling. We investigate the role of nuclear spins in materials with electrically generated spin polarization. The electron spin polarization generated by electrical current in a non-magnetic semiconductor is transferred via dynamic nuclear polarization to the nuclei. The resulting nuclear field is interrogated using Larmor magnetometry. We measure the nuclear field as a function of applied magnetic field, current magnitude and direction, and temperature. An unexpected spatial asymmetry in saturated nuclear field is found. The direction of the nuclear polarization is determined by the directions of the electron spin alignment and external magnetic field, allowing electronic control over the sign of the nuclear alignment direction. Careful study of the nuclear field also enables characterization of the current-induced electron spin polarization in situations that are otherwise experimentally inaccessible. Work supported by AFOSR, NSF and ONR.

  7. Dynamic nuclear polarization of 17O: direct polarization.

    PubMed

    Michaelis, Vladimir K; Corzilius, Björn; Smith, Albert A; Griffin, Robert G

    2013-12-01

    Dynamic nuclear polarization of (17)O was studied using four different polarizing agents: the biradical TOTAPOL and the monoradicals trityl and SA-BDPA, as well as a mixture of the latter two. Field profiles, DNP mechanisms, and enhancements were measured to better understand and optimize directly polarizing this low-gamma quadrupolar nucleus using both mono- and biradical polarizing agents. Enhancements were recorded at <88 K and were >100 using the trityl (OX063) radical and <10 with the other polarizing agents. The >10,000-fold savings in acquisition time enabled a series of biologically relevant small molecules to be studied with small sample sizes and the measurement of various quadrupolar parameters. The results are discussed with comparison to room temperature studies and GIPAW quantum chemical calculations. These experimental results illustrate the strength of high field DNP and the importance of radical selection for studying low-gamma nuclei.

  8. Development on dynamic nuclear polarized targets.

    SciTech Connect

    Penttila, S. I.

    2002-01-01

    Our interest in understanding the spin content of the nucleon has left its marks on the recent development, of the dynamic nuclear polarized (DNP) targets. This can be seen from the targets developed at CERN and SLAC for the measurement of the polarized spin structure functions in deep inelastic scattering. The results of the experiments indicated that less than 30% of the nucleon spin is carried by the quarks. This unpredicted small value initiated planning of new polarized target experiments to determine the gluon polarization on the nucleon using polarized real photons and polarized 'LiD targets. In several facilities very intense polarized photon beams are available at a wide energy range. During the next few years these photon beanis with DNP targets will be used to test the fundamental GDH sum rule. Other DNP target developments are also discussed.

  9. New versions of sources for nuclear polarized negative ion production

    SciTech Connect

    Dudnikov, V.G.; Shabalin, A.L. ); Wojtsekhowski, B.B. ); Belov, A.S.; Kuzik, V.E.; Plohinsky, Y.V.; Yakushev, V.P. )

    1992-10-05

    Several variants of sources for nuclear polarized negative ion production have been proposed and tested. The simple adaptation of a high intensity polarized proton source for nuclear polarized H[sup [minus

  10. Polarization model applied to Uranian radio emission

    NASA Astrophysics Data System (ADS)

    Sawyer, C. B.; Neal, K. L.; Warwick, J. W.

    1991-04-01

    The total power and the degree of circular polarization as measured by the Planetary Radio Astronomy experiments on the Voyager spacecraft are modeled. For a source near the electron cyclotron frequency, the degree of circular polarization is determined by the angle between the wave vector and the field. It is shown that the observed strong circular polarization of Uranian smooth low-frequency (SLF) can be modeled as emission that is beamed along the direction of the magnetic field in a filled cone. The main observational constraints of SLF emission from Uranus are met by conjugate sources at about 21 deg from the magnetic equator.

  11. Voltage-induced conversion of helical to uniform nuclear spin polarization in a quantum wire

    NASA Astrophysics Data System (ADS)

    Kornich, Viktoriia; Stano, Peter; Zyuzin, Alexander A.; Loss, Daniel

    2015-05-01

    We study the effect of bias voltage on the nuclear spin polarization of a ballistic wire, which contains electrons and nuclei interacting via hyperfine interaction. In equilibrium, the localized nuclear spins are helically polarized due to the electron-mediated Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. Focusing here on nonequilibrium, we find that an applied bias voltage induces a uniform polarization, from both helically polarized and unpolarized spins available for spin flips. Once a macroscopic uniform polarization in the nuclei is established, the nuclear spin helix rotates with frequency proportional to the uniform polarization. The uniform nuclear spin polarization monotonically increases as a function of both voltage and temperature, reflecting a thermal activation behavior. Our predictions offer specific ways to test experimentally the presence of a nuclear spin helix polarization in semiconducting quantum wires.

  12. Dynamic nuclear polarization polarizer for sterile use intent.

    PubMed

    Ardenkjaer-Larsen, Jan H; Leach, Andrew M; Clarke, Neil; Urbahn, John; Anderson, Denise; Skloss, Timothy W

    2011-10-01

    A novel polarizer based on the dissolution-dynamic nuclear polarization (DNP) method has been designed, built and tested. The polarizer differs from those previously described by being designed with sterile use intent and being compatible with clinical use. The main features are: (1) an integral, disposable fluid path containing all pharmaceuticals constituting a sterile barrier, (2) a closed-cycle cryogenic system designed to eliminate consumption of liquid cryogens and (3) multi-sample polarization to increase throughput. The fluid path consists of a vial with the agent to be polarized, a pair of concentric inlet and outlet tubes connected to a syringe with dissolution medium and a receiver, respectively. The fluid path can operate at up to 400 K and 2.0 MPa and generates volumes as high as 100 mL. An inline filter removes the amount of electron paramagnetic agent in the final product by more than 100-fold in the case of [1-(13)C]pyruvate. The system uses a sorption pump in conjunction with a conventional cryocooler. The system operates through cycles of pumping to low temperature and regeneration of the sorption pump. The magnet accommodates four samples at the same time. A temperature of less than 1 K was achieved for 68 h (no sample heat loads) with a liquid helium volume of 2.4 L. The regeneration of the liquid helium could be achieved in less than 10 h, and the transition to cold (< 1.2 K) was achieved in less than 90 min. A solid state polarization of 36 ± 4% for [1-(13)C]pyruvic acid was obtained with only 10 mW of microwave power. The loading of a sample adds less than 50 J of heat to the helium bath by introducing the sample over 15 min. The heat load imposed on the helium bath during dissolution was less than 70 J. The measured liquid state polarization was 18 ± 2%.

  13. Nuclear Facilities and Applied Technologies at Sandia

    SciTech Connect

    Wheeler, Dave; Kaiser, Krista; Martin, Lonnie; Hanson, Don; Harms, Gary; Quirk, Tom

    2014-11-28

    The Nuclear Facilities and Applied Technologies organization at Sandia National Laboratories’ Technical Area Five (TA-V) is the leader in advancing nuclear technologies through applied radiation science and unique nuclear environments. This video describes the organization’s capabilities, facilities, and culture.

  14. Optical nuclear spin polarization in quantum dots

    NASA Astrophysics Data System (ADS)

    Li, Ai-Xian; Duan, Su-Qing; Zhang, Wei

    2016-10-01

    Hyperfine interaction between electron spin and randomly oriented nuclear spins is a key issue of electron coherence for quantum information/computation. We propose an efficient way to establish high polarization of nuclear spins and reduce the intrinsic nuclear spin fluctuations. Here, we polarize the nuclear spins in semiconductor quantum dot (QD) by the coherent population trapping (CPT) and the electric dipole spin resonance (EDSR) induced by optical fields and ac electric fields. By tuning the optical fields, we can obtain a powerful cooling background based on CPT for nuclear spin polarization. The EDSR can enhance the spin flip-flop rate which may increase the cooling efficiency. With the help of CPT and EDSR, an enhancement of 1300 times of the electron coherence time can be obtained after a 10-ns preparation time. Project partially supported by the National Natural Science Foundations of China (Grant Nos. 11374039 and 11174042) and the National Basic Research Program of China (Grant Nos. 2011CB922204 and 2013CB632805).

  15. Inhomogeneous dynamic nuclear polarization and suppression of electron polarization decay in a quantum dot

    NASA Astrophysics Data System (ADS)

    Wu, Na; Ding, Wenkui; Shi, Anqi; Zhang, Wenxian

    2016-08-01

    We investigate the dynamic nuclear polarization in a quantum dot. Due to the suppression of direct dipolar and indirect electron-mediated nuclear spin interactions by frequently injected electron spins, our analytical results under independent spin approximation agree well with quantum numerical simulations for a small number of nuclear spins. We find that the acquired nuclear polarization is highly inhomogeneous, proportional to the square of the local electron-nuclear hyperfine interaction constant. Starting from the inhomogeneously polarized nuclear spins, we further show that the electron polarization decay time can be extended 100 times even at a relatively low nuclear polarization.

  16. Microtesla MRI with dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Zotev, Vadim S.; Owens, Tuba; Matlashov, Andrei N.; Savukov, Igor M.; Gomez, John J.; Espy, Michelle A.

    2010-11-01

    Magnetic resonance imaging at microtesla fields is a promising imaging method that combines the pre-polarization technique and broadband signal reception by superconducting quantum interference device (SQUID) sensors to enable in vivo MRI at microtesla-range magnetic fields similar in strength to the Earth magnetic field. Despite significant advances in recent years, the potential of microtesla MRI for biomedical imaging is limited by its insufficient signal-to-noise ratio due to a relatively low sample polarization. Dynamic nuclear polarization (DNP) is a widely used approach that allows polarization enhancement by 2-4 orders of magnitude without an increase in the polarizing field strength. In this work, the first implementation of microtesla MRI with Overhauser DNP and SQUID signal detection is described. The first measurements of carbon-13 NMR spectra at microtesla fields are also reported. The experiments were performed at the measurement field of 96 μT, corresponding to Larmor frequency of 4 kHz for protons and 1 kHz for carbon-13. The Overhauser DNP was carried out at 3.5-5.7 mT fields using rf irradiation at 120 MHz. Objects for imaging included water phantoms and a cactus plant. Aqueous solutions of metabolically relevant sodium bicarbonate, pyruvate, alanine, and lactate, labeled with carbon-13, were used for NMR studies. All the samples were doped with TEMPO free radicals. The Overhauser DNP enabled nuclear polarization enhancement by factor as large as -95 for protons and as large as -200 for carbon-13, corresponding to thermal polarizations at 0.33 T and 1.1 T fields, respectively. These results demonstrate that SQUID-based microtesla MRI can be naturally combined with Overhauser DNP in one system, and that its signal-to-noise performance is greatly improved in this case. They also suggest that microtesla MRI can become an efficient tool for in vivo imaging of hyperpolarized carbon-13, produced by low-temperature dissolution DNP.

  17. Nuclear Polarization of H{sub 2} Molecules formed from Polarized Atoms

    SciTech Connect

    Wise, T.; Balewski, J.T.; Daehnick, W.W.; Doskow, J.; Friesel, D.; Haeberli, W.; Kolster,H.; Lorentz, B.; Meyer, H.O.; Pancella, P.V.; Pollock, R.E.; Przewoski, B.v.; Quin, P.A.; Rathmann, F.; Rinckel, T.; Saha, Swapan K.; Schwartz, B.; Wellinghausen, A.

    2000-12-31

    A planned experiment to measure the nuclear polarization of H{sub 2} molecules formed by recombination of polarized H atoms is described. Polarization will be measured with a longitudinally polarized 200-MeV proton beam and a longitudinally polarized storage cell gas target at the IUCF cooler ring.

  18. Uncertainty minimization in NMR measurements of dynamic nuclear polarization of a proton target for nuclear physics experiments

    SciTech Connect

    Keller, Dustin M.

    2013-11-01

    A comprehensive investigation into the measurement uncertainty in polarization produced by Dynamic Nuclear Polarization is outlined. The polarization data taken during Jefferson Lab experiment E08-007 is used to obtain error estimates and to develop an algorithm to minimize uncertainty of the measurement of polarization in irradiated View the ^14NH_3 targets, which is readily applied to other materials. The target polarization and corresponding uncertainties for E08-007 are reported. The resulting relative uncertainty found in the target polarization is determined to be less than or equal to 3.9%.

  19. Dynamic Nuclear Polarization as Kinetically Constrained Diffusion

    NASA Astrophysics Data System (ADS)

    Karabanov, A.; Wiśniewski, D.; Lesanovsky, I.; Köckenberger, W.

    2015-07-01

    Dynamic nuclear polarization (DNP) is a promising strategy for generating a significantly increased nonthermal spin polarization in nuclear magnetic resonance (NMR) and its applications that range from medicine diagnostics to material science. Being a genuine nonequilibrium effect, DNP circumvents the need for strong magnetic fields. However, despite intense research, a detailed theoretical understanding of the precise mechanism behind DNP is currently lacking. We address this issue by focusing on a simple instance of DNP—so-called solid effect DNP—which is formulated in terms of a quantum central spin model where a single electron is coupled to an ensemble of interacting nuclei. We show analytically that the nonequilibrium buildup of polarization heavily relies on a mechanism which can be interpreted as kinetically constrained diffusion. Beyond revealing this insight, our approach furthermore permits numerical studies of ensembles containing thousands of spins that are typically intractable when formulated in terms of a quantum master equation. We believe that this represents an important step forward in the quest of harnessing nonequilibrium many-body quantum physics for technological applications.

  20. Dynamic Nuclear Polarization as Kinetically Constrained Diffusion.

    PubMed

    Karabanov, A; Wiśniewski, D; Lesanovsky, I; Köckenberger, W

    2015-07-10

    Dynamic nuclear polarization (DNP) is a promising strategy for generating a significantly increased nonthermal spin polarization in nuclear magnetic resonance (NMR) and its applications that range from medicine diagnostics to material science. Being a genuine nonequilibrium effect, DNP circumvents the need for strong magnetic fields. However, despite intense research, a detailed theoretical understanding of the precise mechanism behind DNP is currently lacking. We address this issue by focusing on a simple instance of DNP-so-called solid effect DNP-which is formulated in terms of a quantum central spin model where a single electron is coupled to an ensemble of interacting nuclei. We show analytically that the nonequilibrium buildup of polarization heavily relies on a mechanism which can be interpreted as kinetically constrained diffusion. Beyond revealing this insight, our approach furthermore permits numerical studies of ensembles containing thousands of spins that are typically intractable when formulated in terms of a quantum master equation. We believe that this represents an important step forward in the quest of harnessing nonequilibrium many-body quantum physics for technological applications. PMID:26207453

  1. Dynamic nuclear polarization in a magnetic resonance force microscope experiment.

    PubMed

    Issac, Corinne E; Gleave, Christine M; Nasr, Paméla T; Nguyen, Hoang L; Curley, Elizabeth A; Yoder, Jonilyn L; Moore, Eric W; Chen, Lei; Marohn, John A

    2016-04-01

    We report achieving enhanced nuclear magnetization in a magnetic resonance force microscope experiment at 0.6 tesla and 4.2 kelvin using the dynamic nuclear polarization (DNP) effect. In our experiments a microwire coplanar waveguide delivered radiowaves to excite nuclear spins and microwaves to excite electron spins in a 250 nm thick nitroxide-doped polystyrene sample. Both electron and proton spin resonance were observed as a change in the mechanical resonance frequency of a nearby cantilever having a micron-scale nickel tip. NMR signal, not observable from Curie-law magnetization at 0.6 T, became observable when microwave irradiation was applied to saturate the electron spins. The resulting NMR signal's size, buildup time, dependence on microwave power, and dependence on irradiation frequency was consistent with a transfer of magnetization from electron spins to nuclear spins. Due to the presence of an inhomogeneous magnetic field introduced by the cantilever's magnetic tip, the electron spins in the sample were saturated in a microwave-resonant slice 10's of nm thick. The spatial distribution of the nuclear polarization enhancement factor ε was mapped by varying the frequency of the applied radiowaves. The observed enhancement factor was zero for spins in the center of the resonant slice, was ε = +10 to +20 for spins proximal to the magnet, and was ε = -10 to -20 for spins distal to the magnet. We show that this bipolar nuclear magnetization profile is consistent with cross-effect DNP in a ∼10(5) T m(-1) magnetic field gradient. Potential challenges associated with generating and using DNP-enhanced nuclear magnetization in a nanometer-resolution magnetic resonance imaging experiment are elucidated and discussed. PMID:26964007

  2. Dynamic nuclear polarization in a magnetic resonance force microscope experiment.

    PubMed

    Issac, Corinne E; Gleave, Christine M; Nasr, Paméla T; Nguyen, Hoang L; Curley, Elizabeth A; Yoder, Jonilyn L; Moore, Eric W; Chen, Lei; Marohn, John A

    2016-04-01

    We report achieving enhanced nuclear magnetization in a magnetic resonance force microscope experiment at 0.6 tesla and 4.2 kelvin using the dynamic nuclear polarization (DNP) effect. In our experiments a microwire coplanar waveguide delivered radiowaves to excite nuclear spins and microwaves to excite electron spins in a 250 nm thick nitroxide-doped polystyrene sample. Both electron and proton spin resonance were observed as a change in the mechanical resonance frequency of a nearby cantilever having a micron-scale nickel tip. NMR signal, not observable from Curie-law magnetization at 0.6 T, became observable when microwave irradiation was applied to saturate the electron spins. The resulting NMR signal's size, buildup time, dependence on microwave power, and dependence on irradiation frequency was consistent with a transfer of magnetization from electron spins to nuclear spins. Due to the presence of an inhomogeneous magnetic field introduced by the cantilever's magnetic tip, the electron spins in the sample were saturated in a microwave-resonant slice 10's of nm thick. The spatial distribution of the nuclear polarization enhancement factor ε was mapped by varying the frequency of the applied radiowaves. The observed enhancement factor was zero for spins in the center of the resonant slice, was ε = +10 to +20 for spins proximal to the magnet, and was ε = -10 to -20 for spins distal to the magnet. We show that this bipolar nuclear magnetization profile is consistent with cross-effect DNP in a ∼10(5) T m(-1) magnetic field gradient. Potential challenges associated with generating and using DNP-enhanced nuclear magnetization in a nanometer-resolution magnetic resonance imaging experiment are elucidated and discussed.

  3. Theory of dynamic nuclear polarization and feedback in quantum dots

    NASA Astrophysics Data System (ADS)

    Economou, Sophia E.; Barnes, Edwin

    2014-04-01

    An electron confined in a quantum dot interacts with its local nuclear spin environment through the hyperfine contact interaction. This interaction combined with external control and relaxation or measurement of the electron spin allows for the generation of dynamic nuclear polarization. The quantum nature of the nuclear bath, along with the interplay of coherent external fields and incoherent dynamics in these systems renders a wealth of intriguing phenomena seen in recent experiments such as electron Zeeman frequency focusing, hysteresis, and line dragging. We develop in detail a fully quantum, self-consistent theory that can be applied to such experiments and that moreover has predictive power. Our theory uses the operator sum representation formalism in order to incorporate the incoherent dynamics caused by the additional, Markovian bath, which in self-assembled dots is the vacuum field responsible for electron-hole optical recombination. The beauty of this formalism is that it reduces the complexity of the problem by encoding the joint dynamics of the external coherent and incoherent driving in an effective dynamical map that only acts on the electron spin subspace. This, together with the separation of time scales in the problem, allows for a tractable and analytically solvable formalism. The key role of entanglement between the electron spin and the nuclear spins in the formation of dynamic nuclear polarization naturally follows from our solution. We demonstrate the theory in detail for an optical pulsed experiment and present an in-depth discussion and physical explanation of our results.

  4. Dynamic nuclear polarization at high magnetic fields

    PubMed Central

    Maly, Thorsten; Debelouchina, Galia T.; Bajaj, Vikram S.; Hu, Kan-Nian; Joo, Chan-Gyu; Mak–Jurkauskas, Melody L.; Sirigiri, Jagadishwar R.; van der Wel, Patrick C. A.; Herzfeld, Judith; Temkin, Richard J.; Griffin, Robert G.

    2009-01-01

    Dynamic nuclear polarization (DNP) is a method that permits NMR signal intensities of solids and liquids to be enhanced significantly, and is therefore potentially an important tool in structural and mechanistic studies of biologically relevant molecules. During a DNP experiment, the large polarization of an exogeneous or endogeneous unpaired electron is transferred to the nuclei of interest (I) by microwave (μw) irradiation of the sample. The maximum theoretical enhancement achievable is given by the gyromagnetic ratios (γe/γl), being ∼660 for protons. In the early 1950s, the DNP phenomenon was demonstrated experimentally, and intensively investigated in the following four decades, primarily at low magnetic fields. This review focuses on recent developments in the field of DNP with a special emphasis on work done at high magnetic fields (≥5 T), the regime where contemporary NMR experiments are performed. After a brief historical survey, we present a review of the classical continuous wave (cw) DNP mechanisms—the Overhauser effect, the solid effect, the cross effect, and thermal mixing. A special section is devoted to the theory of coherent polarization transfer mechanisms, since they are potentially more efficient at high fields than classical polarization schemes. The implementation of DNP at high magnetic fields has required the development and improvement of new and existing instrumentation. Therefore, we also review some recent developments in μw and probe technology, followed by an overview of DNP applications in biological solids and liquids. Finally, we outline some possible areas for future developments. PMID:18266416

  5. Nuclear polarization effects in big bang nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Voronchev, Victor T.; Nakao, Yasuyuki

    2015-10-01

    A standard nuclear reaction network for big bang nucleosynthesis (BBN) simulations operates with spin-averaged nuclear inputs—unpolarized reaction cross sections. At the same time, the major part of reactions controlling the abundances of light elements is spin dependent, i.e., their cross sections depend on the mutual orientation of reacting particle spins. Primordial magnetic fields in the BBN epoch may to a certain degree polarize particles and thereby affect some reactions between them, introducing uncertainties in standard BBN predictions. To clarify the points, we have examined the effects of induced polarization on key BBN reactions—p (n ,γ )d , d (d ,p )t , d (d ,n )He 3 , t (d ,n )α , He 3 (n ,p )t , He 3 (d ,p )α , Li 7 (p ,α )α , Be 7 (n ,p )Li 7 —and the abundances of elements with A ≤7 . It has been obtained that the magnetic field with the strength B0≤1012 G (at the temperature of 109 K ) has almost no effect on the reaction cross sections, and the spin polarization mechanism plays a minor role in the element production, changing the abundances at most by 0.01%. However, if the magnetic field B0 reaches 1015 G its effect on the key reactions appears and becomes appreciable at B0≳1016 G . In particular, it has been found that such a field can increase the p (n ,γ )d cross section (relevant to the starting point of BBN) by a factor of 2 and at the same time almost block the He 3 (n ,p )t reaction responsible for the interconversion of A =3 nuclei in the early Universe. This suggests that the spin polarization effects may become important in nonstandard scenarios of BBN considering the existence of local magnetic bubbles inside which the field can reach ˜1015 G .

  6. Optical Polarization of Nuclear Spins in Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Falk, Abram L.; Klimov, Paul V.; Ivády, Viktor; Szász, Krisztián; Christle, David J.; Koehl, William F.; Gali, Ádám; Awschalom, David D.

    2015-06-01

    We demonstrate optically pumped dynamic nuclear polarization of 29Si nuclear spins that are strongly coupled to paramagnetic color centers in 4 H - and 6 H -SiC. The 9 9 % ±1 % degree of polarization that we observe at room temperature corresponds to an effective nuclear temperature of 5 μ K . By combining ab initio theory with the experimental identification of the color centers' optically excited states, we quantitatively model how the polarization derives from hyperfine-mediated level anticrossings. These results lay a foundation for SiC-based quantum memories, nuclear gyroscopes, and hyperpolarized probes for magnetic resonance imaging.

  7. Temporal and spatial evolution of nuclear polarization in optically pumped InP

    NASA Astrophysics Data System (ADS)

    Miller, J. B.; Klug, C. A.; Sauer, K. L.; Yesinowski, J. P.

    2015-06-01

    The electron-nuclear interaction in optically pumped NMR of semiconductors manifests itself through changes in spectral features (resonance shifts, linewidths, signal amplitudes) and through the magnitude of the nuclear-spin polarization. We show that these spectral features can provide a measure of the parameters that govern the optical pumping process: electron-nuclear cross-relaxation rate, Bohr radius and fractional occupancy of the optically relevant defect (ORD), and electron polarization at the ORD. Applying a model of the spatial and temporal evolution of the nuclear spins under optical pumping to 31 P in semi-insulating InP we find an ORD Bohr radius of 6 nm, independent of the electron polarization used to fit the data, confirming the ORD is a shallow donor. For an electron polarization of -0.15 , the ORD fractional occupancy is 0.02, leading to an electron-nuclear cross-relaxation time of 0.20 s and a hyperfine frequency shift of 8.1 kHz for super-bandgap irradiation. Allowing the electron polarization to vary in the model constrained to the hyperfine shift data, we find the fractional occupancy and electron-nuclear cross-relaxation rate to be approximately inversely proportional to the electron polarization. From the long-time evolution of the nuclear polarization we calculate an ORD density of 5 ×1015cm-3 .

  8. Dynamic nuclear polarization surface enhanced NMR spectroscopy.

    PubMed

    Rossini, Aaron J; Zagdoun, Alexandre; Lelli, Moreno; Lesage, Anne; Copéret, Christophe; Emsley, Lyndon

    2013-09-17

    Many of the functions and applications of advanced materials result from their interfacial structures and properties. However, the difficulty in characterizing the surface structure of these materials at an atomic level can often slow their further development. Solid-state NMR can probe surface structure and complement established surface science techniques, but its low sensitivity often limits its application. Many materials have low surface areas and/or low concentrations of active/surface sites. Dynamic nuclear polarization (DNP) is one intriguing method to enhance the sensitivity of solid-state NMR experiments by several orders of magnitude. In a DNP experiment, the large polarization of unpaired electrons is transferred to surrounding nuclei, which provides a maximum theoretical DNP enhancement of ∼658 for (1)H NMR. In this Account, we discuss the application of DNP to enhance surface NMR signals, an approach known as DNP surface enhanced NMR spectroscopy (DNP SENS). Enabling DNP for these systems requires bringing an exogeneous radical solution into contact with surfaces without diluting the sample. We proposed the incipient wetness impregnation technique (IWI), a well-known method in materials science, to impregnate porous and particulate materials with just enough radical containing solution to fill the porous volume. IWI offers several advantages: it is extremely simple, provides a uniform wetting of the surface, and does not increase the sample volume or substantially reduce the concentration of the sample. This Account describes the basic principles behind DNP SENS through results obtained for mesoporous and nanoparticulate samples impregnated with radical solutions. We also discuss the quantification of the overall sensitivity enhancements obtained with DNP SENS and compare that with ordinary room temperature NMR spectroscopy. We then review the development of radicals and solvents that give the best possible enhancements today. With the best

  9. Nuclear reactivity control using laser induced polarization

    DOEpatents

    Bowman, Charles D.

    1990-01-01

    A control element for reactivity control of a fission source provides an atomic density of .sup.3 He in a control volume which is effective to control criticality as the .sup.3 He is spin-polarized. Spin-polarization of the .sup.3 He affects the cross section of the control volume for fission neturons and hence, the reactivity. An irradiation source is directed within the .sup.3 He for spin-polarizing the .sup.3 He. An alkali-metal vapor may be included with the .sup.3 He where a laser spin-polarizes the alkali-metal atoms which in turn, spin-couple with .sup.3 He to spin-polarize the .sup.3 He atoms.

  10. Nuclear reactivity control using laser induced polarization

    DOEpatents

    Bowman, Charles D.

    1991-01-01

    A control element for reactivity control of a fission source provides an atomic density of .sup.3 He in a control volume which is effective to control criticality as the .sup.3 He is spin-polarized. Spin-polarization of the .sup.3 He affects the cross section of the control volume for fission neutrons and hence, the reactivity. An irradiation source is directed within the .sup.3 He for spin-polarizing the .sup.3 He. An alkali-metal vapor may be included with the .sup.3 He where a laser spin-polarizes the alkali-metal atoms which in turn, spin-couple with .sup.3 He to spin-polarize the .sup.3 He atoms.

  11. Polarization-sensitive optical coherence tomography applied to intervertebral disk

    NASA Astrophysics Data System (ADS)

    Matcher, Stephen J.; Winlove, Peter; Gangnus, Sergei V.

    2003-07-01

    Polarization-sensitive optical coherence tomography (PSOCT) is a powerful new optical imaging modality that is sensitive to the birefringence properties of tissues. It thus has potential applications in studying the large-scale ordering of collagen fibers within connective tisues and changes related to pathology. As a tissue for study by PSOCT, intervertebral disk respresents an interesting system as the collagen organization is believed to show pronounced variations with depth, on a spatial scale of about 100 μm. We have used a polarization-sensitive optical coherence tomography system to measure the birefringence properties of bovine caudal intervertebral disk and compared this with equine flexor tendon. The result for equine tendon, δ = (3.0 +/- 0.5)x10-3 at 1.3 μm, is in broad agreement with values reported for bovine tendon, while bovine intervertebral disk displays a birefringence of about half this, δ = 1.2 x 10-3 at 1.3 μm. While tendon appears to show a uniform fast-axis over 0.8 mm depth, intervertebral disk shows image contrast at all orientations relative to a linearly polarized input beam, suggesting a variation in fast-axis orientation with depth. These initial results suggest that PSOCT could be a useful tool to study collagen organization within this tissue and its variation with applied load and disease.

  12. Optically enhanced nuclear cross polarization in acridine-doped fluorene

    SciTech Connect

    Oshiro, C.M.

    1982-06-01

    The objective of this work has been to create large polarizations of the dilute /sup 13/C nuclei in the solid state. The idea was to create /sup 1/H polarizations larger than Boltzmann and to use the proton enhanced nuclear induction spectroscopy cross polarization technique to then transfer this large polarization to the /sup 13/C spin system. Optical Nuclear Polarization (ONP) of acridine-doped fluorene single crystals was studied. In addition, ONP of powdered samples of the acridine-doped fluorene was studied. In general, many compounds do not crystallize easily or do not form large crystals suitable for NMR experiments. Powdered, amorphous and randomly dispersed samples are generally far more readily available than single crystals. One objective of this work has been to (first) create large /sup 1/H polarizations. Although large optical proton polarizations in single crystals have been reported previously, optically generated polarizations in powdered samples have not been reported. For these reasons, ONP studies of powdered samples of the acridine-doped fluorene were also undertaken. Using ONP in combination with the proton enhanced nuclear induction spectroscopy experiment, large /sup 13/C polarizations have been created in fluorene single crystals. These large /sup 13/C polarizations have permitted the determination of the seven incongruent chemical shielding tensors of the fluorene molecule. Part 2 of this thesis describes the proton enhanced nuclear induction spectroscopy experiment. Part 3 describes the ONP experiment. Part 4 is a description of the experimental set-up. Part 5 describes the data analysis for the determination of the chemical shielding tensors. Part 6 presents the results of the ONP experiments performed in this work and the chemical shielding tensors determined.

  13. Apparatus and method for polarizing polarizable nuclear species

    DOEpatents

    Hersman, F. William; Leuschner, Mark; Carberry, Jeannette

    2005-09-27

    The present invention is a polarizing process involving a number of steps. The first step requires moving a flowing mixture of gas, the gas at least containing a polarizable nuclear species and vapor of at least one alkali metal, with a transport velocity that is not negligible when compared with the natural velocity of diffusive transport. The second step is propagating laser light in a direction, preferably at least partially through a polarizing cell. The next step is directing the flowing gas along a direction generally opposite to the direction of laser light propagating. The next step is containing the flowing gas mixture in the polarizing cell. The final step is immersing the polarizing cell in a magnetic field. These steps can be initiated in any order, although the flowing gas, the propagating laser and the magnetic field immersion must be concurrently active for polarization to occur.

  14. Nuclear polarization corrections to the μ4He+ Lamb shift.

    PubMed

    Ji, C; Nevo Dinur, N; Bacca, S; Barnea, N

    2013-10-01

    Stimulated by the proton radius conundrum, measurements of the Lamb shift in various light muonic atoms are planned at PSI. The aim is to extract the rms charge radius with high precision, limited by the uncertainty in the nuclear polarization corrections. We present an ab initio calculation of the nuclear polarization for μ(4)He(+) leading to an energy correction in the 2S-2P transitions of δ(pol)(A)=-2.47 meV ±6%. We use two different state-of-the-art nuclear Hamiltonians and utilize the Lorentz integral transform with hyperspherical harmonics expansion as few-body methods. We take into account the leading multipole contributions, plus Coulomb, relativistic, and finite-nucleon-size corrections. Our main source of uncertainty is the nuclear Hamiltonian, which currently limits the attainable accuracy. Our predictions considerably reduce the uncertainty with respect to previous estimates and should be instrumental to the μ(4)He(+) experiment planned for 2013.

  15. Nuclear magnetic resonance imaging with hyper-polarized noble gases

    SciTech Connect

    Schmidt, D.M.; George, J.S.; Penttila, S.I.; Caprihan, A.

    1997-10-01

    This is the final report of a six-month, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The nuclei of noble gases can be hyper polarized through a laser-driven spin exchange to a degree many orders of magnitude larger than that attainable by thermal polarization without requiring a strong magnetic field. The increased polarization from the laser pumping enables a good nuclear magnetic resonance (NMR) signal from a gas. The main goal of this project was to demonstrate diffusion-weighted imaging of such hyper-polarized noble gas with magnetic resonance imaging (MRI). Possible applications include characterizing porosity of materials and dynamically imaging pressure distributions in biological or acoustical systems.

  16. Hybrid polarizing solids for pure hyperpolarized liquids through dissolution dynamic nuclear polarization.

    PubMed

    Gajan, David; Bornet, Aurélien; Vuichoud, Basile; Milani, Jonas; Melzi, Roberto; van Kalkeren, Henri A; Veyre, Laurent; Thieuleux, Chloé; Conley, Matthew P; Grüning, Wolfram R; Schwarzwälder, Martin; Lesage, Anne; Copéret, Christophe; Bodenhausen, Geoffrey; Emsley, Lyndon; Jannin, Sami

    2014-10-14

    Hyperpolarization of substrates for magnetic resonance spectroscopy (MRS) and imaging (MRI) by dissolution dynamic nuclear polarization (D-DNP) usually involves saturating the ESR transitions of polarizing agents (PAs; e.g., persistent radicals embedded in frozen glassy matrices). This approach has shown enormous potential to achieve greatly enhanced nuclear spin polarization, but the presence of PAs and/or glassing agents in the sample after dissolution can raise concerns for in vivo MRI applications, such as perturbing molecular interactions, and may induce the erosion of hyperpolarization in spectroscopy and MRI. We show that D-DNP can be performed efficiently with hybrid polarizing solids (HYPSOs) with 2,2,6,6-tetramethyl-piperidine-1-oxyl radicals incorporated in a mesostructured silica material and homogeneously distributed along its pore channels. The powder is wetted with a solution containing molecules of interest (for example, metabolites for MRS or MRI) to fill the pore channels (incipient wetness impregnation), and DNP is performed at low temperatures in a very efficient manner. This approach allows high polarization without the need for glass-forming agents and is applicable to a broad range of substrates, including peptides and metabolites. During dissolution, HYPSO is physically retained by simple filtration in the cryostat of the DNP polarizer, and a pure hyperpolarized solution is collected within a few seconds. The resulting solution contains the pure substrate, is free from any paramagnetic or other pollutants, and is ready for in vivo infusion. PMID:25267650

  17. Hybrid polarizing solids for pure hyperpolarized liquids through dissolution dynamic nuclear polarization

    PubMed Central

    Gajan, David; Bornet, Aurélien; Vuichoud, Basile; Milani, Jonas; Melzi, Roberto; van Kalkeren, Henri A.; Veyre, Laurent; Thieuleux, Chloé; Conley, Matthew P.; Grüning, Wolfram R.; Schwarzwälder, Martin; Lesage, Anne; Copéret, Christophe; Bodenhausen, Geoffrey; Emsley, Lyndon; Jannin, Sami

    2014-01-01

    Hyperpolarization of substrates for magnetic resonance spectroscopy (MRS) and imaging (MRI) by dissolution dynamic nuclear polarization (D-DNP) usually involves saturating the ESR transitions of polarizing agents (PAs; e.g., persistent radicals embedded in frozen glassy matrices). This approach has shown enormous potential to achieve greatly enhanced nuclear spin polarization, but the presence of PAs and/or glassing agents in the sample after dissolution can raise concerns for in vivo MRI applications, such as perturbing molecular interactions, and may induce the erosion of hyperpolarization in spectroscopy and MRI. We show that D-DNP can be performed efficiently with hybrid polarizing solids (HYPSOs) with 2,2,6,6-tetramethyl-piperidine-1-oxyl radicals incorporated in a mesostructured silica material and homogeneously distributed along its pore channels. The powder is wetted with a solution containing molecules of interest (for example, metabolites for MRS or MRI) to fill the pore channels (incipient wetness impregnation), and DNP is performed at low temperatures in a very efficient manner. This approach allows high polarization without the need for glass-forming agents and is applicable to a broad range of substrates, including peptides and metabolites. During dissolution, HYPSO is physically retained by simple filtration in the cryostat of the DNP polarizer, and a pure hyperpolarized solution is collected within a few seconds. The resulting solution contains the pure substrate, is free from any paramagnetic or other pollutants, and is ready for in vivo infusion. PMID:25267650

  18. Polarizing agents and mechanisms for high-field dynamic nuclear polarization of frozen dielectric solids.

    PubMed

    Hu, Kan-Nian

    2011-09-01

    This article provides an overview of polarizing mechanisms involved in high-frequency dynamic nuclear polarization (DNP) of frozen biological samples at temperatures maintained using liquid nitrogen, compatible with contemporary magic-angle spinning (MAS) nuclear magnetic resonance (NMR). Typical DNP experiments require unpaired electrons that are usually exogenous in samples via paramagnetic doping with polarizing agents. Thus, the resulting nuclear polarization mechanism depends on the electron and nuclear spin interactions induced by the paramagnetic species. The Overhauser Effect (OE) DNP, which relies on time-dependent spin-spin interactions, is excluded from our discussion due the lack of conducting electrons in frozen aqueous solutions containing biological entities. DNP of particular interest to us relies primarily on time-independent, spin-spin interactions for significant electron-nucleus polarization transfer through mechanisms such as the Solid Effect (SE), the Cross Effect (CE) or Thermal Mixing (TM), involving one, two or multiple electron spins, respectively. Derived from monomeric radicals initially used in high-field DNP experiments, bi- or multiple-radical polarizing agents facilitate CE/TM to generate significant NMR signal enhancements in dielectric solids at low temperatures (<100 K). For example, large DNP enhancements (∼300 times at 5 T) from a biologically compatible biradical, 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL), have enabled high-resolution MAS NMR in sample systems existing in submicron domains or embedded in larger biomolecular complexes. The scope of this review is focused on recently developed DNP polarizing agents for high-field applications and leads up to future developments per the CE DNP mechanism. Because DNP experiments are feasible with a solid-state microwave source when performed at <20K, nuclear polarization using lower microwave power (<100 mW) is possible by forcing a high proportion of biradicals to

  19. Quantum mechanical theory of dynamic nuclear polarization in solid dielectrics

    PubMed Central

    Hu, Kan-Nian; Debelouchina, Galia T.; Smith, Albert A.; Griffin, Robert G.

    2011-01-01

    Microwave driven dynamic nuclear polarization (DNP) is a process in which the large polarization present in an electron spin reservoir is transferred to nuclei, thereby enhancing NMR signal intensities. In solid dielectrics there are three mechanisms that mediate this transfer—the solid effect (SE), the cross effect (CE), and thermal mixing (TM). Historically these mechanisms have been discussed theoretically using thermodynamic parameters and average spin interactions. However, the SE and the CE can also be modeled quantum mechanically with a system consisting of a small number of spins and the results provide a foundation for the calculations involving TM. In the case of the SE, a single electron–nuclear spin pair is sufficient to explain the polarization mechanism, while the CE requires participation of two electrons and a nuclear spin, and can be used to understand the improved DNP enhancements observed using biradical polarizing agents. Calculations establish the relations among the electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) frequencies and the microwave irradiation frequency that must be satisfied for polarization transfer via the SE or the CE. In particular, if δ, Δ < ω0I, where δ and Δ are the homogeneous linewidth and inhomogeneous breadth of the EPR spectrum, respectively, we verify that the SE occurs when ωM = ω0S ± ω0I, where ωM, ω0S and ω0I are, respectively, the microwave, and the EPR and NMR frequencies. Alternatively, when Δ > ω0I > δ, the CE dominates the polarization transfer. This two-electron process is optimized when ω0S1−ω0S2=ω0I and ωM∼ω0S1 orω0S2, where ω0S1 and ω0S2 are the EPR Larmor frequencies of the two electrons. Using these matching conditions, we calculate the evolution of the density operator from electron Zeeman order to nuclear Zeeman order for both the SE and the CE. The results provide insights into the influence of the microwave irradiation field, the

  20. The spin-temperature theory of dynamic nuclear polarization and nuclear spin-lattice relaxation

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Wollan, D. S.

    1974-01-01

    A detailed derivation of the equations governing dynamic nuclear polarization (DNP) and nuclear spin lattice relaxation by use of the spin temperature theory has been carried to second order in a perturbation expansion of the density matrix. Nuclear spin diffusion in the rapid diffusion limit and the effects of the coupling of the electron dipole-dipole reservoir (EDDR) with the nuclear spins are incorporated. The complete expression for the dynamic nuclear polarization has been derived and then examined in detail for the limit of well resolved solid effect transitions. Exactly at the solid effect transition peaks, the conventional solid-effect DNP results are obtained, but with EDDR effects on the nuclear relaxation and DNP leakage factor included. Explicit EDDR contributions to DNP are discussed, and a new DNP effect is predicted.

  1. Oocyte Polarization Is Coupled to the Chromosomal Bouquet, a Conserved Polarized Nuclear Configuration in Meiosis

    PubMed Central

    Elkouby, Yaniv M.; Jamieson-Lucy, Allison; Mullins, Mary C.

    2016-01-01

    The source of symmetry breaking in vertebrate oocytes is unknown. Animal—vegetal oocyte polarity is established by the Balbiani body (Bb), a conserved structure found in all animals examined that contains an aggregate of specific mRNAs, proteins, and organelles. The Bb specifies the oocyte vegetal pole, which is key to forming the embryonic body axes as well as the germline in most vertebrates. How Bb formation is regulated and how its asymmetric position is established are unknown. Using quantitative image analysis, we trace oocyte symmetry breaking in zebrafish to a nuclear asymmetry at the onset of meiosis called the chromosomal bouquet. The bouquet is a universal feature of meiosis where all telomeres cluster to one pole on the nuclear envelope, facilitating chromosomal pairing and meiotic recombination. We show that Bb precursor components first localize with the centrosome to the cytoplasm adjacent to the telomere cluster of the bouquet. They then aggregate around the centrosome in a specialized nuclear cleft that we identified, assembling the early Bb. We show that the bouquet nuclear events and the cytoplasmic Bb precursor localization are mechanistically coordinated by microtubules. Thus the animal—vegetal axis of the oocyte is aligned to the nuclear axis of the bouquet. We further show that the symmetry breaking events lay upstream to the only known regulator of Bb formation, the Bucky ball protein. Our findings link two universal features of oogenesis, the Bb and the chromosomal bouquet, to oocyte polarization. We propose that a meiotic—vegetal center couples meiosis and oocyte patterning. Our findings reveal a novel mode of cellular polarization in meiotic cells whereby cellular and nuclear polarity are aligned. We further reveal that in zygotene nests, intercellular cytoplasmic bridges remain between oocytes and that the position of the cytoplasmic bridge coincides with the location of the centrosome meiotic—vegetal organizing center. These

  2. Oocyte Polarization Is Coupled to the Chromosomal Bouquet, a Conserved Polarized Nuclear Configuration in Meiosis.

    PubMed

    Elkouby, Yaniv M; Jamieson-Lucy, Allison; Mullins, Mary C

    2016-01-01

    The source of symmetry breaking in vertebrate oocytes is unknown. Animal-vegetal oocyte polarity is established by the Balbiani body (Bb), a conserved structure found in all animals examined that contains an aggregate of specific mRNAs, proteins, and organelles. The Bb specifies the oocyte vegetal pole, which is key to forming the embryonic body axes as well as the germline in most vertebrates. How Bb formation is regulated and how its asymmetric position is established are unknown. Using quantitative image analysis, we trace oocyte symmetry breaking in zebrafish to a nuclear asymmetry at the onset of meiosis called the chromosomal bouquet. The bouquet is a universal feature of meiosis where all telomeres cluster to one pole on the nuclear envelope, facilitating chromosomal pairing and meiotic recombination. We show that Bb precursor components first localize with the centrosome to the cytoplasm adjacent to the telomere cluster of the bouquet. They then aggregate around the centrosome in a specialized nuclear cleft that we identified, assembling the early Bb. We show that the bouquet nuclear events and the cytoplasmic Bb precursor localization are mechanistically coordinated by microtubules. Thus the animal-vegetal axis of the oocyte is aligned to the nuclear axis of the bouquet. We further show that the symmetry breaking events lay upstream to the only known regulator of Bb formation, the Bucky ball protein. Our findings link two universal features of oogenesis, the Bb and the chromosomal bouquet, to oocyte polarization. We propose that a meiotic-vegetal center couples meiosis and oocyte patterning. Our findings reveal a novel mode of cellular polarization in meiotic cells whereby cellular and nuclear polarity are aligned. We further reveal that in zygotene nests, intercellular cytoplasmic bridges remain between oocytes and that the position of the cytoplasmic bridge coincides with the location of the centrosome meiotic-vegetal organizing center. These results

  3. Applied nuclear physics in support of SBSS

    SciTech Connect

    Strottman, D.

    1995-10-01

    Since the advent of the 800-MeV proton linear accelerator over 3 decades ago, the facilities on the Clinton P. Anderson Meson Physics Facility (LAMPF) mesa have pioneered many developments that provide unique capabilities within the Department of Energy (DOE) complex and in the world. New technologies based on the use of the world`s most intense, medium-energy linac, LAMPF, are being developed. They include destruction of long-lived components of nuclear waste, plutonium burning, energy production, production of tritium, and experiments for the science-based stockpile stewardship (SBSS) program. The design, assessment, and safety analysis of potential facilities involve the understanding of complex combinations of nuclear processes, which in turn establish new requirements on nuclear data that transcend the traditional needs of the fission and fusion reactor communities. Other areas of technology such as neutron and proton therapy applications are also placing new requirements on nuclear data. The proposed Los Alamos Neutron Science Center (LANSCE) now under discussion combined with the appropriate instrumentation will have unique features and capabilities of which there were previously only aspirations.

  4. Solid effect in magic angle spinning dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Corzilius, Björn; Smith, Albert A.; Griffin, Robert G.

    2012-08-01

    For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ω _0 ^{ - 2} field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ɛ = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of 1H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear 1H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements to address the unfavorable field dependence of the solid effect.

  5. Nuclear depolarization and absolute sensitivity in magic-angle spinning cross effect dynamic nuclear polarization.

    PubMed

    Mentink-Vigier, Frédéric; Paul, Subhradip; Lee, Daniel; Feintuch, Akiva; Hediger, Sabine; Vega, Shimon; De Paëpe, Gaël

    2015-09-14

    Over the last two decades solid state Nuclear Magnetic Resonance has witnessed a breakthrough in increasing the nuclear polarization, and thus experimental sensitivity, with the advent of Magic Angle Spinning Dynamic Nuclear Polarization (MAS-DNP). To enhance the nuclear polarization of protons, exogenous nitroxide biradicals such as TOTAPOL or AMUPOL are routinely used. Their efficiency is usually assessed as the ratio between the NMR signal intensity in the presence and the absence of microwave irradiation εon/off. While TOTAPOL delivers an enhancement εon/off of about 60 on a model sample, the more recent AMUPOL is more efficient: >200 at 100 K. Such a comparison is valid as long as the signal measured in the absence of microwaves is merely the Boltzmann polarization and is not affected by the spinning of the sample. However, recent MAS-DNP studies at 25 K by Thurber and Tycko (2014) have demonstrated that the presence of nitroxide biradicals combined with sample spinning can lead to a depolarized nuclear state, below the Boltzmann polarization. In this work we demonstrate that TOTAPOL and AMUPOL both lead to observable depolarization at ≈110 K, and that the magnitude of this depolarization is radical dependent. Compared to the static sample, TOTAPOL and AMUPOL lead, respectively, to nuclear polarization losses of up to 20% and 60% at a 10 kHz MAS frequency, while Trityl OX63 does not depolarize at all. This experimental work is analyzed using a theoretical model that explains how the depolarization process works under MAS and gives new insights into the DNP mechanism and into the spin parameters, which are relevant for the efficiency of a biradical. In light of these results, the outstanding performance of AMUPOL must be revised and we propose a new method to assess the polarization gain for future radicals.

  6. Covariance Spectroscopy Applied to Nuclear Radiation Detection

    SciTech Connect

    Trainham, R., Tinsley, J., Keegan, R., Quam, W.

    2011-09-01

    Covariance spectroscopy is a method of processing second order moments of data to obtain information that is usually absent from average spectra. In nuclear radiation detection it represents a generalization of nuclear coincidence techniques. Correlations and fluctuations in data encode valuable information about radiation sources, transport media, and detection systems. Gaining access to the extra information can help to untangle complicated spectra, uncover overlapping peaks, accelerate source identification, and even sense directionality. Correlations existing at the source level are particularly valuable since many radioactive isotopes emit correlated gammas and neutrons. Correlations also arise from interactions within detector systems, and from scattering in the environment. In particular, correlations from Compton scattering and pair production within a detector array can be usefully exploited in scenarios where direct measurement of source correlations would be unfeasible. We present a covariance analysis of a few experimental data sets to illustrate the utility of the concept.

  7. PRESTO polarization transfer to quadrupolar nuclei: Implications for dynamic nuclear polarization

    DOE PAGES

    Perras, Frederic A.; Kobayashi, Takeshi; Pruski, Marek

    2015-08-04

    In this study, we show both experimentally and numerically on a series of model systems that in experiments involving transfer of magnetization from 1H to the quadrupolar nuclei under magic-angle-spinning (MAS), the PRESTO technique consistently outperforms traditionally used cross polarization (CP), affording more quantitative intensities, improved lineshapes, better overall sensitivity, and straightforward optimization. This advantage derives from the fact that PRESTO circumvents the convoluted and uncooperative spin dynamics during the CP transfer under MAS, by replacing the spin-locking of quadrupolar nuclei with a single central transition selective 90° pulse and using a symmetry-based recoupling sequence in the 1H channel. Thismore » is important in the context of dynamic nuclear polarization (DNP) NMR of quadrupolar nuclei, where the efficient transfer of enhanced 1H polarization is desired to obtain the highest sensitivity.« less

  8. PRESTO polarization transfer to quadrupolar nuclei: Implications for dynamic nuclear polarization

    SciTech Connect

    Perras, Frederic A.; Kobayashi, Takeshi; Pruski, Marek

    2015-08-04

    In this study, we show both experimentally and numerically on a series of model systems that in experiments involving transfer of magnetization from 1H to the quadrupolar nuclei under magic-angle-spinning (MAS), the PRESTO technique consistently outperforms traditionally used cross polarization (CP), affording more quantitative intensities, improved lineshapes, better overall sensitivity, and straightforward optimization. This advantage derives from the fact that PRESTO circumvents the convoluted and uncooperative spin dynamics during the CP transfer under MAS, by replacing the spin-locking of quadrupolar nuclei with a single central transition selective 90° pulse and using a symmetry-based recoupling sequence in the 1H channel. This is important in the context of dynamic nuclear polarization (DNP) NMR of quadrupolar nuclei, where the efficient transfer of enhanced 1H polarization is desired to obtain the highest sensitivity.

  9. Magnetic-field cycling instrumentation for dynamic nuclear polarization-nuclear magnetic resonance using photoexcited triplets.

    PubMed

    Kagawa, Akinori; Negoro, Makoto; Takeda, Kazuyuki; Kitagawa, Masahiro

    2009-04-01

    To advance static solid-state NMR with hyperpolarized nuclear spins, a system has been developed enabling dynamic nuclear polarization (DNP) using electron spins in the photoexcited triplet state with X-band microwave apparatus, followed by static solid-state nuclear magnetic resonance (NMR) experiments using the polarized nuclear-spin system with a goniometer. In order to perform the DNP and NMR procedures in different magnetic fields, the DNP system and the NMR system are spatially separated, between which the sample can be shuttled while its orientation is controlled in a reproducible fashion. We demonstrate that the system developed in this work is operational for solid-state NMR with hyperpolarized nuclear-spin systems in static organic materials, and also discuss the application of our system.

  10. High Field Dynamic Nuclear Polarization NMR with Surfactant Sheltered Biradicals

    PubMed Central

    2015-01-01

    We illustrate the ability to place a water-insoluble biradical, bTbk, into a glycerol/water matrix with the assistance of a surfactant, sodium octyl sulfate (SOS). This surfactant approach enables a previously water insoluble biradical, bTbk, with favorable electron–electron dipolar coupling to be used for dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) experiments in frozen, glassy, aqueous media. Nuclear Overhauser enhancement (NOE) and paramagnetic relaxation enhancement (PRE) experiments are conducted to determine the distribution of urea and several biradicals within the SOS macromolecular assembly. We also demonstrate that SOS assemblies are an effective approach by which mixed biradicals are created through an assembly process. PMID:24506193

  11. Applying RFID technology in nuclear materials management.

    SciTech Connect

    Tsai, H.; Chen, K.; Liu, Y.; Norair, J. P.; Bellamy, S.; Shuler, J.; SRL; Savi Technology; DOE

    2008-01-01

    The Packaging Certification Program (PCP) of US Department of Energy (DOE) Environmental Management (EM), Office of Safety Management and Operations (EM-60), has developed a radio frequency identification (RFID) system for the management of nuclear materials. Argonne National Laboratory, a PCP supporting laboratory, and Savi Technology, a Lockheed Martin Company, are collaborating in the development of the RFID system, a process that involves hardware modification (form factor, seal sensor and batteries), software development and irradiation experiments. Savannah River National Laboratory and Argonne will soon field test the active RFID system on Model 9975 drums, which are used for storage and transportation of fissile and radioactive materials. Potential benefits of the RFID system are enhanced safety and security, reduced need for manned surveillance, real time access of status and history data, and overall cost effectiveness.

  12. Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization.

    PubMed

    Mentink-Vigier, Frederic; Akbey, Ümit; Oschkinat, Hartmut; Vega, Shimon; Feintuch, Akiva

    2015-09-01

    Magic Angle Spinning (MAS) combined with Dynamic Nuclear Polarization (DNP) has been proven in recent years to be a very powerful method for increasing solid-state NMR signals. Since the advent of biradicals such as TOTAPOL to increase the nuclear polarization new classes of radicals, with larger molecular weight and/or different spin properties have been developed. These have led to unprecedented signal gain, with varying results for different experimental parameters, in particular the microwave irradiation strength, the static field, and the spinning frequency. Recently it has been demonstrated that sample spinning imposes DNP enhancement processes that differ from the active DNP mechanism in static samples as upon sample spinning the DNP enhancements are the results of energy level anticrossings occurring periodically during each rotor cycle. In this work we present experimental results with regards to the MAS frequency dependence of the DNP enhancement profiles of four nitroxide-based radicals at two different sets of temperature, 110 and 160K. In fact, different magnitudes of reduction in enhancement are observed with increasing spinning frequency. Our simulation code for calculating MAS-DNP powder enhancements of small model spin systems has been improved to extend our studies of the influence of the interaction and relaxation parameters on powder enhancements. To achieve a better understanding we simulated the spin dynamics of a single three-spin system {ea-eb-n} during its steady state rotor periods and used the Landau-Zener formula to characterize the influence of the different anti-crossings on the polarizations of the system and their necessary action for reaching steady state conditions together with spin relaxation processes. Based on these model calculations we demonstrate that the maximum steady state nuclear polarization cannot become larger than the maximum polarization difference between the two electrons during the steady state rotor cycle. This

  13. Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization.

    PubMed

    Mentink-Vigier, Frederic; Akbey, Ümit; Oschkinat, Hartmut; Vega, Shimon; Feintuch, Akiva

    2015-09-01

    Magic Angle Spinning (MAS) combined with Dynamic Nuclear Polarization (DNP) has been proven in recent years to be a very powerful method for increasing solid-state NMR signals. Since the advent of biradicals such as TOTAPOL to increase the nuclear polarization new classes of radicals, with larger molecular weight and/or different spin properties have been developed. These have led to unprecedented signal gain, with varying results for different experimental parameters, in particular the microwave irradiation strength, the static field, and the spinning frequency. Recently it has been demonstrated that sample spinning imposes DNP enhancement processes that differ from the active DNP mechanism in static samples as upon sample spinning the DNP enhancements are the results of energy level anticrossings occurring periodically during each rotor cycle. In this work we present experimental results with regards to the MAS frequency dependence of the DNP enhancement profiles of four nitroxide-based radicals at two different sets of temperature, 110 and 160K. In fact, different magnitudes of reduction in enhancement are observed with increasing spinning frequency. Our simulation code for calculating MAS-DNP powder enhancements of small model spin systems has been improved to extend our studies of the influence of the interaction and relaxation parameters on powder enhancements. To achieve a better understanding we simulated the spin dynamics of a single three-spin system {ea-eb-n} during its steady state rotor periods and used the Landau-Zener formula to characterize the influence of the different anti-crossings on the polarizations of the system and their necessary action for reaching steady state conditions together with spin relaxation processes. Based on these model calculations we demonstrate that the maximum steady state nuclear polarization cannot become larger than the maximum polarization difference between the two electrons during the steady state rotor cycle. This

  14. Dynamic nuclear polarization of nucleic acid with endogenously bound manganese.

    PubMed

    Wenk, Patricia; Kaushik, Monu; Richter, Diane; Vogel, Marc; Suess, Beatrix; Corzilius, Björn

    2015-09-01

    We report the direct dynamic nuclear polarization (DNP) of (13)C nuclei of a uniformly [(13)C,(15)N]-labeled, paramagnetic full-length hammerhead ribozyme (HHRz) complex with Mn(2+) where the enhanced polarization is fully provided by the endogenously bound metal ion and no exogenous polarizing agent is added. A (13)C enhancement factor of ε = 8 was observed by intra-complex DNP at 9.4 T. In contrast, "conventional" indirect and direct DNP experiments were performed using AMUPol as polarizing agent where we obtained a (1)H enhancement factor of ε ≈ 250. Comparison with the diamagnetic (Mg(2+)) HHRz complex shows that the presence of Mn(2+) only marginally influences the (DNP-enhanced) NMR properties of the RNA. Furthermore two-dimensional correlation spectra ((15)N-(13)C and (13)C-(13)C) reveal structural inhomogeneity in the frozen, amorphous state indicating the coexistence of several conformational states. These demonstrations of intra-complex DNP using an endogenous metal ion as well as DNP-enhanced MAS NMR of RNA in general yield important information for the development of new methods in structural biology. PMID:26219517

  15. Mechanisms of dynamic nuclear polarization in insulating solids

    NASA Astrophysics Data System (ADS)

    Can, T. V.; Ni, Q. Z.; Griffin, R. G.

    2015-04-01

    Dynamic nuclear polarization (DNP) is a technique used to enhance signal intensities in NMR experiments by transferring the high polarization of electrons to their surrounding nuclei. The past decade has witnessed a renaissance in the development of DNP, especially at high magnetic fields, and its application in several areas including biophysics, chemistry, structural biology and materials science. Recent technical and theoretical advances have expanded our understanding of established experiments: for example, the cross effect DNP in samples spinning at the magic angle. Furthermore, new experiments suggest that our understanding of the Overhauser effect and its applicability to insulating solids needs to be re-examined. In this article, we summarize important results of the past few years and provide quantum mechanical explanations underlying these results. We also discuss future directions of DNP and current limitations, including the problem of resolution in protein spectra recorded at 80-100 K.

  16. Mechanisms of Dynamic Nuclear Polarization in Insulating Solids

    PubMed Central

    Can, T.V.; Ni, Q.Z.; Griffin, R.G.

    2015-01-01

    Dynamic nuclear polarization (DNP) is a technique used to enhance signal intensities in NMR experiments by transferring the high polarization of electrons to their surrounding nuclei. The past decade has witnessed a renaissance in the development of DNP, especially at high magnetic fields, and its application in several areas including biophysics, chemistry, structural biology and materials science. Recent technical and theoretical advances have expanded our understanding of established experiments: for example, the cross effect DNP in samples spinning at the magic angle. Furthermore, new experiments suggest that our understanding of the Overhauser effect and its applicability to insulating solids needs to be re-examined. In this article, we summarize important results of the past few years and provide quantum mechanical explanations underlying these results. We also discuss future directions of DNP and current limitations, including the problem of resolution in protein spectra recorded at 80–100 K. PMID:25797002

  17. A method for dynamic nuclear polarization enhancement of membrane proteins.

    PubMed

    Smith, Adam N; Caporini, Marc A; Fanucci, Gail E; Long, Joanna R

    2015-01-26

    Dynamic nuclear polarization (DNP) magic-angle spinning (MAS) solid-state NMR (ssNMR) spectroscopy has the potential to enhance NMR signals by orders of magnitude and to enable NMR characterization of proteins which are inherently dilute, such as membrane proteins. In this work spin-labeled lipid molecules (SL-lipids), when used as polarizing agents, lead to large and relatively homogeneous DNP enhancements throughout the lipid bilayer and to an embedded lung surfactant mimetic peptide, KL4 . Specifically, DNP MAS ssNMR experiments at 600 MHz/395 GHz on KL4 reconstituted in liposomes containing SL-lipids reveal DNP enhancement values over two times larger for KL4 compared to liposome suspensions containing the biradical TOTAPOL. These findings suggest an alternative sample preparation strategy for DNP MAS ssNMR studies of lipid membranes and integral membrane proteins. PMID:25504310

  18. Fast passage dynamic nuclear polarization on rotating solids

    NASA Astrophysics Data System (ADS)

    Mentink-Vigier, Frederic; Akbey, Ümit; Hovav, Yonatan; Vega, Shimon; Oschkinat, Hartmut; Feintuch, Akiva

    2012-11-01

    Magic Angle Spinning (MAS) Dynamic Nuclear Polarization (DNP) has proven to be a very powerful way to improve the signal to noise ratio of NMR experiments on solids. The experiments have in general been interpreted considering the Solid-Effect (SE) and Cross-Effect (CE) DNP mechanisms while ignoring the influence of sample spinning. In this paper, we show experimental data of MAS-DNP enhancements of 1H and 13C in proline and SH3 protein in glass forming water/glycerol solvent containing TOTAPOL. We also introduce a theoretical model that aims at explaining how the nuclear polarization is built in MAS-DNP experiments. By using Liouville space based simulations to include relaxation on two simple spin models, {electron-nucleus} and {electron-electron-nucleus}, we explain how the basic MAS-SE-DNP and MAS-CE-DNP processes work. The importance of fast energy passages and short level anti-crossing is emphasized and the differences between static DNP and MAS-DNP is explained. During a single rotor cycle the enhancement in the {electron-electron-nucleus} system arises from MAS-CE-DNP involving at least three kinds of two-level fast passages: an electron-electron dipolar anti-crossing, a single quantum electron MW encounter and an anti-crossing at the CE condition inducing nuclear polarization in- or decrements. Numerical, powder-averaged, simulations were performed in order to check the influence of the experimental parameters on the enhancement efficiencies. In particular we show that the spinning frequency dependence of the theoretical MAS-CE-DNP enhancement compares favorably with the experimental 1H and 13C MAS-DNP enhancements of proline and SH3.

  19. Fast passage dynamic nuclear polarization on rotating solids.

    PubMed

    Mentink-Vigier, Frederic; Akbey, Umit; Hovav, Yonatan; Vega, Shimon; Oschkinat, Hartmut; Feintuch, Akiva

    2012-11-01

    Magic Angle Spinning (MAS) Dynamic Nuclear Polarization (DNP) has proven to be a very powerful way to improve the signal to noise ratio of NMR experiments on solids. The experiments have in general been interpreted considering the Solid-Effect (SE) and Cross-Effect (CE) DNP mechanisms while ignoring the influence of sample spinning. In this paper, we show experimental data of MAS-DNP enhancements of (1)H and (13)C in proline and SH3 protein in glass forming water/glycerol solvent containing TOTAPOL. We also introduce a theoretical model that aims at explaining how the nuclear polarization is built in MAS-DNP experiments. By using Liouville space based simulations to include relaxation on two simple spin models, {electron-nucleus} and {electron-electron-nucleus}, we explain how the basic MAS-SE-DNP and MAS-CE-DNP processes work. The importance of fast energy passages and short level anti-crossing is emphasized and the differences between static DNP and MAS-DNP is explained. During a single rotor cycle the enhancement in the {electron-electron-nucleus} system arises from MAS-CE-DNP involving at least three kinds of two-level fast passages: an electron-electron dipolar anti-crossing, a single quantum electron MW encounter and an anti-crossing at the CE condition inducing nuclear polarization in- or decrements. Numerical, powder-averaged, simulations were performed in order to check the influence of the experimental parameters on the enhancement efficiencies. In particular we show that the spinning frequency dependence of the theoretical MAS-CE-DNP enhancement compares favorably with the experimental (1)H and (13)C MAS-DNP enhancements of proline and SH3.

  20. Polarization enhanced Nuclear Quadrupole Resonance with an atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Malone, Michael W.; Barrall, Geoffrey A.; Espy, Michelle A.; Monti, Mark C.; Alexson, Dimitri A.; Okamitsu, Jeffrey K.

    2016-05-01

    Nuclear Quadrupole Resonance (NQR) has been demonstrated for the detection of 14-N in explosive compounds. Application of a material specific radio-frequency (RF) pulse excites a response typically detected with a wire- wound antenna. NQR is non-contact and material specific, however fields produced by NQR are typically very weak, making demonstration of practical utility challenging. For certain materials, the NQR signal can be increased by transferring polarization from hydrogen nuclei to nitrogen nuclei using external magnetic fields. This polarization enhancement (PE) can enhance the NQR signal by an order of magnitude or more. Atomic magnetometers (AM) have been shown to improve detection sensitivity beyond a conventional antenna by a similar amount. AM sensors are immune to piezo-electric effects that hamper conventional NQR, and can be combined to form a gradiometer for effective RF noise cancellation. In principle, combining polarization enhancement with atomic magnetometer detection should yield improvement in signal-to-noise ratio that is the product of the two methods, 100-fold or more over conventional NQR. However both methods are even more exotic than traditional NQR, and have never been combined due to challenges in operating a large magnetic field and ultra-sensitive magnetic field sensor in proximity. Here we present NQR with and without PE with an atomic magnetometer, demonstrating signal enhancement greater than 20-fold for ammonium nitrate. We also demonstrate PE for PETN using a traditional coil for detection with an enhancement factor of 10. Experimental methods and future applications are discussed.

  1. Optical Control of Spatial Patterning of Nuclear Polarization in GaAs

    NASA Astrophysics Data System (ADS)

    King, Jonathan; Li, Yunpu; Peng, Le; Tamargo, Maria; Meriles, Carlos; Reimer, Jeffrey

    2011-03-01

    We present new results on the optical polarization of nuclear spins in gallium arsenide. Previous work has identified the contact hyperfine interaction at shallow donors as the mechanism for helicity dependent nuclear polarization. We show a new regime, where donors are only partially occupied, where nuclear quadrupolar relaxation at shallow donors is the dominant mechanism. Since quadrupolar relaxation is helicity independent, the incident light polarization may be tuned such that the two relaxation mechanisms drive the nuclear spins to opposite signs of polarization. We show that incident light wavelength and power may be tuned to create spatial patterns of varying donor occupation in a single sample, which in turn creates a pattern of positive and negative nuclear polarization. We have developed an analytical mode which accurately describes the bulk NMR signal in terms of irradiation power and wavelength. We also present stray-field NMR imaging experiments showing direct observation of the patterned nuclear polarization.

  2. A 3D-printed high power nuclear spin polarizer.

    PubMed

    Nikolaou, Panayiotis; Coffey, Aaron M; Walkup, Laura L; Gust, Brogan M; LaPierre, Cristen D; Koehnemann, Edward; Barlow, Michael J; Rosen, Matthew S; Goodson, Boyd M; Chekmenev, Eduard Y

    2014-01-29

    Three-dimensional printing with high-temperature plastic is used to enable spin exchange optical pumping (SEOP) and hyperpolarization of xenon-129 gas. The use of 3D printed structures increases the simplicity of integration of the following key components with a variable temperature SEOP probe: (i) in situ NMR circuit operating at 84 kHz (Larmor frequencies of (129)Xe and (1)H nuclear spins), (ii) <0.3 nm narrowed 200 W laser source, (iii) in situ high-resolution near-IR spectroscopy, (iv) thermoelectric temperature control, (v) retroreflection optics, and (vi) optomechanical alignment system. The rapid prototyping endowed by 3D printing dramatically reduces production time and expenses while allowing reproducibility and integration of "off-the-shelf" components and enables the concept of printing on demand. The utility of this SEOP setup is demonstrated here to obtain near-unity (129)Xe polarization values in a 0.5 L optical pumping cell, including ∼74 ± 7% at 1000 Torr xenon partial pressure, a record value at such high Xe density. Values for the (129)Xe polarization exponential build-up rate [(3.63 ± 0.15) × 10(-2) min(-1)] and in-cell (129)Xe spin-lattice relaxation time (T1 = 2.19 ± 0.06 h) for 1000 Torr Xe were in excellent agreement with the ratio of the gas-phase polarizations for (129)Xe and Rb (PRb ∼ 96%). Hyperpolarization-enhanced (129)Xe gas imaging was demonstrated with a spherical phantom following automated gas transfer from the polarizer. Taken together, these results support the development of a wide range of chemical, biochemical, material science, and biomedical applications.

  3. A 3D-Printed High Power Nuclear Spin Polarizer

    PubMed Central

    Nikolaou, Panayiotis; Coffey, Aaron M.; Walkup, Laura L.; Gust, Brogan M.; LaPierre, Cristen D.; Koehnemann, Edward; Barlow, Michael J.; Rosen, Matthew S.; Goodson, Boyd M.; Chekmenev, Eduard Y.

    2015-01-01

    Three-dimensional printing with high-temperature plastic is used to enable spin exchange optical pumping (SEOP) and hyperpolarization of xenon-129 gas. The use of 3D printed structures increases the simplicity of integration of the following key components with a variable temperature SEOP probe: (i) in situ NMR circuit operating at 84 kHz (Larmor frequencies of 129Xe and 1H nuclear spins), (ii) <0.3 nm narrowed 200 W laser source, (iii) in situ high-resolution near-IR spectroscopy, (iv) thermoelectric temperature control, (v) retroreflection optics, and (vi) optomechanical alignment system. The rapid prototyping endowed by 3D printing dramatically reduces production time and expenses while allowing reproducibility and integration of “off-the-shelf” components and enables the concept of printing on demand. The utility of this SEOP setup is demonstrated here to obtain near-unity 129Xe polarization values in a 0.5 L optical pumping cell, including ~74 ± 7% at 1000 Torr xenon partial pressure, a record value at such high Xe density. Values for the 129Xe polarization exponential build-up rate [(3.63 ± 0.15) × 10−2 min−1] and in-cell 129Xe spin−lattice relaxation time (T1 = 2.19 ± 0.06 h) for 1000 Torr Xe were in excellent agreement with the ratio of the gas-phase polarizations for 129Xe and Rb (PRb ~ 96%). Hyperpolarization-enhanced 129Xe gas imaging was demonstrated with a spherical phantom following automated gas transfer from the polarizer. Taken together, these results support the development of a wide range of chemical, biochemical, material science, and biomedical applications. PMID:24400919

  4. Solid state nuclear magnetic resonance with magic-angle spinning and dynamic nuclear polarization below 25 K.

    PubMed

    Thurber, Kent R; Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2013-01-01

    We describe an apparatus for solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS) at 20-25 K and 9.4 Tesla. The MAS NMR probe uses helium to cool the sample space and nitrogen gas for MAS drive and bearings, as described earlier, but also includes a corrugated waveguide for transmission of microwaves from below the probe to the sample. With a 30 mW circularly polarized microwave source at 264 GHz, MAS at 6.8 kHz, and 21 K sample temperature, greater than 25-fold enhancements of cross-polarized (13)C NMR signals are observed in spectra of frozen glycerol/water solutions containing the triradical dopant DOTOPA-TEMPO when microwaves are applied. As demonstrations, we present DNP-enhanced one-dimensional and two-dimensional (13)C MAS NMR spectra of frozen solutions of uniformly (13)C-labeled l-alanine and melittin, a 26-residue helical peptide that we have synthesized with four uniformly (13)C-labeled amino acids. PMID:23238592

  5. Solid state nuclear magnetic resonance with magic-angle spinning and dynamic nuclear polarization below 25 K

    NASA Astrophysics Data System (ADS)

    Thurber, Kent R.; Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2013-01-01

    We describe an apparatus for solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS) at 20-25 K and 9.4 Tesla. The MAS NMR probe uses helium to cool the sample space and nitrogen gas for MAS drive and bearings, as described earlier [1], but also includes a corrugated waveguide for transmission of microwaves from below the probe to the sample. With a 30 mW circularly polarized microwave source at 264 GHz, MAS at 6.8 kHz, and 21 K sample temperature, greater than 25-fold enhancements of cross-polarized 13C NMR signals are observed in spectra of frozen glycerol/water solutions containing the triradical dopant DOTOPA-TEMPO when microwaves are applied. As demonstrations, we present DNP-enhanced one-dimensional and two-dimensional 13C MAS NMR spectra of frozen solutions of uniformly 13C-labeled L-alanine and melittin, a 26-residue helical peptide that we have synthesized with four uniformly 13C-labeled amino acids.

  6. Solid state nuclear magnetic resonance with magic-angle spinning and dynamic nuclear polarization below 25 K

    PubMed Central

    Thurber, Kent R.; Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2012-01-01

    We describe an apparatus for solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS) at 20–25 K and 9.4 Tesla. The MAS NMR probe uses helium to cool the sample space and nitrogen gas for MAS drive and bearings, as described earlier (Thurber et al., J. Magn. Reson. 2008) [1], but also includes a corrugated waveguide for transmission of microwaves from below the probe to the sample. With a 30 mW circularly polarized microwave source at 264 GHz, MAS at 6.8 kHz, and 21 K sample temperature, greater than 25-fold enhancements of cross-polarized 13C NMR signals are observed in spectra of frozen glycerol/water solutions containing the triradical dopant DOTOPA-TEMPO when microwaves are applied. As demonstrations, we present DNP-enhanced one-dimensional and two-dimensional 13C MAS NMR spectra of frozen solutions of uniformly 13C-labeled L-alanine and melittin, a 26-residue helical peptide that we have synthesized with four uniformly 13C-labeled amino acids. PMID:23238592

  7. Polarization of nuclear spins by a cold nanoscale resonator

    SciTech Connect

    Butler, Mark C.; Weitekamp, Daniel P.

    2011-12-15

    A cold nanoscale resonator coupled to a system of nuclear spins can induce spin relaxation. In the low-temperature limit where spin-lattice interactions are ''frozen out,'' spontaneous emission by nuclear spins into a resonant mechanical mode can become the dominant mechanism for cooling the spins to thermal equilibrium with their environment. We provide a theoretical framework for the study of resonator-induced cooling of nuclear spins in this low-temperature regime. Relaxation equations are derived from first principles, in the limit where energy donated by the spins to the resonator is quickly dissipated into the cold bath that damps it. A physical interpretation of the processes contributing to spin polarization is given. For a system of spins that have identical couplings to the resonator, the interaction Hamiltonian conserves spin angular momentum, and the resonator cannot relax the spins to thermal equilibrium unless this symmetry is broken by the spin Hamiltonian. The mechanism by which such a spin system becomes ''trapped'' away from thermal equilibrium can be visualized using a semiclassical model, which shows how an indirect spin-spin interaction arises from the coupling of multiple spins to one resonator. The internal spin Hamiltonian can affect the polarization process in two ways: (1) By modifying the structure of the spin-spin correlations in the energy eigenstates, and (2) by splitting the degeneracy within a manifold of energy eigenstates, so that zero-frequency off-diagonal terms in the density matrix are converted to oscillating coherences. Shifting the frequencies of these coherences sufficiently far from zero suppresses the development of resonator-induced correlations within the manifold during polarization from a totally disordered state. Modification of the spin-spin correlations by means of either mechanism affects the strength of the fluctuating spin dipole that drives the resonator. In the case where product states can be chosen as energy

  8. Dynamic Nuclear Polarization (DNP) solid-state NMR spectroscopy, a new approach to study humic material?

    NASA Astrophysics Data System (ADS)

    Knicker, Heike; Lange, Sascha; van Rossum, Barth; Oschkinat, Hartmut

    2016-04-01

    Compared to solution NMR spectroscopy, solid-state NMR spectra suffer from broad resonance lines and low resolution. This could be overcome by the use of 2-dimenstional solid-state NMR pulse sequences. Until recently, this approach has been unfeasible as a routine tool in soil chemistry, mainly because of the low NMR sensitivity of the respective samples. A possibility to circumvent those sensitivity problems represents high-field Dynamic Nuclear Polarization (DNP) solid-state NMR spectroscopy (Barnes et al., 2008), allowing considerable signal enhancements (Akbey et al., 2010). This is achieved by a microwave-driven transfer of polarization from a paramagnetic center to nuclear spins. Application of DNP to MAS spectra of biological systems (frozen solutions) showed enhancements of the factor 40 to 50 (Hall et al., 1997). Enhancements of this magnitude, thus may enable the use of at least some of the 2D solid-state NMR techniques that are presently already applied for pure proteins but are difficult to apply to soil peptides in their complex matrix. After adjusting the required acquisition parameters to the system "soil organic matter", lower but still promising enhancement factors were achieved. Additional optimization was performed and allowed the acquisition of 2D 13C and 15N solid-state NMR spectra of humified 13C and 15N enriched plant residues. Within the present contribution, the first solid-state DNP NMR spectra of humic material are presented. Those data demonstrate the great potential of this approach which certainly opens new doors for a better understanding of biochemical processes in soils, sediments and water. Akbey, Ü., Franks, W.T., Linden, A., Lange, S., Griffin, R.G., van Rossum, B.-J., Oschkinat, H., 2010. Dynamic nuclear polarization of deuterated proteins. Angewandte Chemie International Edition 49, 7803-7806. Barnes, A.B., De Paëpe, G., van der Wel, P.C.A., Hu, K.N., Joo, C.G., Bajaj, V.S., Mak-Jurkauskas, M.L., Sirigiri, J.R., Herzfeld, J

  9. Chemistry and biochemistry of 13C hyperpolarized magnetic resonance using dynamic nuclear polarization

    PubMed Central

    Keshari, Kayvan R.; Wilson, David M.

    2014-01-01

    The study of transient chemical phenomena by conventional NMR has proved elusive, particularly for non-1H nuclei. For 13C, hyperpolarization using the dynamic nuclear polarization (DNP) technique has emerged as a powerful means to improve SNR. The recent development of rapid dissolution DNP methods has facilitated previously impossible in vitro and in vivo study of small molecules. This review presents the basics of the DNP technique, identification of appropriate DNP substrates, and approaches to increase hyperpolarized signal lifetimes. Also addressed are the biochemical events to which DNP-NMR has been applied, with descriptions of several probes that have met with in vivo success. PMID:24363044

  10. Boundary between the thermal and statistical polarization regimes in a nuclear spin ensemble

    SciTech Connect

    Herzog, B. E.; Cadeddu, D.; Xue, F.; Peddibhotla, P.; Poggio, M.

    2014-07-28

    As the number of spins in an ensemble is reduced, the statistical fluctuations in its polarization eventually exceed the mean thermal polarization. This transition has now been surpassed in a number of recent nuclear magnetic resonance experiments, which achieve nanometer-scale detection volumes. Here, we measure nanometer-scale ensembles of nuclear spins in a KPF{sub 6} sample using magnetic resonance force microscopy. In particular, we investigate the transition between regimes dominated by thermal and statistical nuclear polarization. The ratio between the two types of polarization provides a measure of the number of spins in the detected ensemble.

  11. Coherent transfer of nuclear spin polarization in field-cycling NMR experiments

    SciTech Connect

    Pravdivtsev, Andrey N.; Yurkovskaya, Alexandra V.; Ivanov, Konstantin L.; Vieth, Hans-Martin

    2013-12-28

    Coherent polarization transfer effects in a coupled spin network have been studied over a wide field range. The transfer mechanism is based on exciting zero-quantum coherences between the nuclear spin states by means of non-adiabatic field jump from high to low magnetic field. Subsequent evolution of these coherences enables conversion of spin order in the system, which is monitored after field jump back to high field. Such processes are most efficient when the spin system passes through an avoided level crossing during the field variation. The polarization transfer effects have been demonstrated for N-acetyl histidine, which has five scalar coupled protons; the initial spin order has been prepared by applying RF-pulses at high magnetic field. The observed oscillatory transfer kinetics is taken as a clear indication of a coherent mechanism; level crossing effects have also been demonstrated. The experimental data are in very good agreement with the theoretical model of coherent polarization transfer. The method suggested is also valid for other types of initial polarization in the spin system, most notably, for spin hyperpolarization.

  12. Coherent transfer of nuclear spin polarization in field-cycling NMR experiments.

    PubMed

    Pravdivtsev, Andrey N; Yurkovskaya, Alexandra V; Vieth, Hans-Martin; Ivanov, Konstantin L

    2013-12-28

    Coherent polarization transfer effects in a coupled spin network have been studied over a wide field range. The transfer mechanism is based on exciting zero-quantum coherences between the nuclear spin states by means of non-adiabatic field jump from high to low magnetic field. Subsequent evolution of these coherences enables conversion of spin order in the system, which is monitored after field jump back to high field. Such processes are most efficient when the spin system passes through an avoided level crossing during the field variation. The polarization transfer effects have been demonstrated for N-acetyl histidine, which has five scalar coupled protons; the initial spin order has been prepared by applying RF-pulses at high magnetic field. The observed oscillatory transfer kinetics is taken as a clear indication of a coherent mechanism; level crossing effects have also been demonstrated. The experimental data are in very good agreement with the theoretical model of coherent polarization transfer. The method suggested is also valid for other types of initial polarization in the spin system, most notably, for spin hyperpolarization. PMID:24387362

  13. Nuclear polarization study: new frontiers for tests of QED in heavy highly charged ions.

    PubMed

    Volotka, Andrey V; Plunien, Günter

    2014-07-11

    A systematic investigation of the nuclear polarization effects in one- and few-electron heavy ions is presented. The nuclear polarization corrections in the zeroth and first orders in 1/Z are evaluated to the binding energies, the hyperfine splitting, and the bound-electron g factor. It is shown that the nuclear polarization contributions can be substantially canceled simultaneously with the rigid nuclear corrections. This allows for new prospects for probing the QED effects in a strong electromagnetic field and the determination of fundamental constants.

  14. Nuclear polarization study: new frontiers for tests of QED in heavy highly charged ions.

    PubMed

    Volotka, Andrey V; Plunien, Günter

    2014-07-11

    A systematic investigation of the nuclear polarization effects in one- and few-electron heavy ions is presented. The nuclear polarization corrections in the zeroth and first orders in 1/Z are evaluated to the binding energies, the hyperfine splitting, and the bound-electron g factor. It is shown that the nuclear polarization contributions can be substantially canceled simultaneously with the rigid nuclear corrections. This allows for new prospects for probing the QED effects in a strong electromagnetic field and the determination of fundamental constants. PMID:25062173

  15. Nuclear spin polarized H and D by means of spin-exchange optical pumping

    NASA Astrophysics Data System (ADS)

    Stenger, Jörn; Grosshauser, Carsten; Kilian, Wolfgang; Nagengast, Wolfgang; Ranzenberger, Bernd; Rith, Klaus; Schmidt, Frank

    1998-01-01

    Optically pumped spin-exchange sources for polarized hydrogen and deuterium atoms have been demonstrated to yield high atomic flow and high electron spin polarization. For maximum nuclear polarization the source has to be operated in spin temperature equilibrium, which has already been demonstrated for hydrogen. In spin temperature equilibrium the nuclear spin polarization PI equals the electron spin polarization PS for hydrogen and is even larger than PS for deuterium. We discuss the general properties of spin temperature equilibrium for a sample of deuterium atoms. One result are the equations PI=4PS/(3+PS2) and Pzz=PSṡPI, where Pzz is the nuclear tensor polarization. Furthermore we demonstrate that the deuterium atoms from our source are in spin temperature equilibrium within the experimental accuracy.

  16. Is solid-state NMR enhanced by dynamic nuclear polarization?

    PubMed

    Lee, Daniel; Hediger, Sabine; De Paëpe, Gaël

    2015-01-01

    The recent trend of high-field (~5-20 T), low-temperature (~100 K) ssNMR combined with dynamic nuclear polarization (DNP) under magic angle spinning (MAS) conditions is analyzed. A brief overview of the current theory of hyperpolarization for so-called MAS-DNP experiments is given, along with various reasons why the DNP-enhancement, the ratio of the NMR signal intensities obtained in the presence and absence of microwave irradiation suitable for hyperpolarization, should not be used alone to gauge the value of performing MAS-DNP experiments relative to conventional ssNMR. This is demonstrated through a dissection of the current conditions required for MAS-DNP with particular attention to resulting absolute sensitivities and spectral resolution. Consequently, sample preparation methods specifically avoiding the surplus of glass-forming solvents so as to improve the absolute sensitivity and resolution are discussed, as are samples that are intrinsically pertinent for MAS-DNP studies (high surface area, amorphous, and porous). Owing to their pertinence, examples of recent applications on these types of samples where chemically-relevant information has been obtained that would have been impossible without the sensitivity increases bestowed by MAS-DNP are also detailed. Additionally, a promising further implementation for MAS-DNP is exampled, whereby the sensitivity improvements shown for (correlation) spectroscopy of nuclei at low natural isotopic abundance, facilitate internuclear distance measurements, especially for long distances (absence of dipolar truncation). Finally, we give some speculative perspectives for MAS-DNP.

  17. Simulation of subnanosecond streamers in atmospheric-pressure air: Effects of polarity of applied voltage pulse

    NASA Astrophysics Data System (ADS)

    Babaeva, N. Yu.; Naidis, G. V.

    2016-08-01

    Results of simulation of subnanosecond streamer propagation in corona gap configuration, obtained in the framework of 2D fluid model, are presented. Effects related with the polarity of a voltage pulse applied to the stressed electrode are discussed. It is argued that these effects (dependence of the discharge current and propagation velocity on the polarity of applied voltage) observed in experiments can be attributed to the difference in initial (preceding the streamer formation) distributions of charged species inside the gap. This difference can be caused by preionization (at negative polarity) of the gas inside the discharge gap by runaway electrons. Calculated streamers have large widths (up to 1 cm) and move with velocities in the range of 109-1010 cm s-1, similar to experimental data.

  18. Measurement of the nuclear polarization of hydrogen and deuterium molecules using a Lamb-shift polarimeter

    SciTech Connect

    Engels, Ralf Gorski, Robert; Grigoryev, Kiril; Mikirtychyants, Maxim; Rathmann, Frank; Seyfarth, Hellmut; Ströher, Hans; Weiss, Philipp; Kochenda, Leonid; Kravtsov, Peter; Trofimov, Viktor; Tschernov, Nikolay; Vasilyev, Alexander; Vznuzdaev, Marat; Schieck, Hans Paetz gen.

    2014-10-15

    Lamb-shift polarimeters are used to measure the nuclear polarization of protons and deuterons at energies of a few keV. In combination with an ionizer, the polarization of hydrogen and deuterium atoms was determined after taking into account the loss of polarization during the ionization process. The present work shows that the nuclear polarization of hydrogen or deuterium molecules can be measured as well, by ionizing the molecules and injecting the H{sub 2}{sup +} (or D{sub 2}{sup +}) ions into the Lamb-shift polarimeter.

  19. Self-Polarization and Dynamical Cooling of Nuclear Spins in Double Quantum Dots

    NASA Astrophysics Data System (ADS)

    Rudner, M. S.; Levitov, L. S.

    2007-07-01

    The spin-blockade regime of double quantum dots features coupled dynamics of electron and nuclear spins resulting from the hyperfine interaction. We explain observed nuclear self-polarization via a mechanism based on feedback of the Overhauser shift on electron energy levels, and propose to use the instability toward self-polarization as a vehicle for controlling the nuclear spin distribution. In the dynamics induced by a properly chosen time-dependent magnetic field, nuclear spin fluctuations can be suppressed significantly below the thermal level.

  20. Confinement and Diffusion Effects in Dynamical Nuclear Polarization in Low Dimensional Nanostructures

    NASA Astrophysics Data System (ADS)

    Henriksen, Dan; Tifrea, Ionel

    2012-02-01

    We investigate the dynamic nuclear polarization as it results from the hyperfine coupling between nonequilibrium electronic spins and nuclear spins in semiconductor nanostructures. The natural confinement provided by low dimensional nanostructures is responsible for an efficient nuclear spin - electron spin hyperfine coupling [1] and for a reduced value of the nuclear spin diffusion constant [2]. In the case of optical pumping, the induced nuclear spin polarization is position dependent even in the presence of nuclear spin diffusion. This effect should be measurable via optically induced nuclear magnetic resonance or time-resolved Faraday rotation experiments. We discuss the implications of our calculations for the case of GaAs quantum well structures.[4pt] [1] I. Tifrea and M. E. Flatt'e, Phys. Rev. B 84, 155319 (2011).[0pt] [2] A. Malinowski and R. T. Harley, Solid State Commun. 114, 419 (2000).

  1. Effect of Lanthanide Ions on Dynamic Nuclear Polarization Enhancement and Liquid State T1 Relaxation

    PubMed Central

    Gordon, Jeremy; Fain, Sean B.; Rowland, Ian J

    2012-01-01

    In the dynamic nuclear polarization process, microwave irradiation facilitates exchange of polarization from a radical’s unpaired electron to nuclear spins at cryogenic temperatures, increasing polarization by >10000. Doping samples with Gd3+ ions further increases the achievable solid-state polarization. However, upon dissolution, paramagnetic lanthanide metals can be potent relaxation agents, decreasing liquid-state polarization. Here, the effects of lanthanide metals on the solid and liquid-state magnetic properties of [1-13C]pyruvate are studied. The results show that in addition to gadolinium, holmium not only increases the achievable polarization but also the rate of polarization. Liquid-state relaxation studies found that unlike gadolinium, holmium minimally affects T1. Additionally, results reveal that linear contrast agents dissociate in pyruvic acid, greatly reducing liquid-state T1. While macrocyclic agents do not readily dissociate, they yield lower solid-state polarization. Results indicate that polarization with free lanthanides and subsequent chelation during dissolution produces the highest polarization enhancement while minimizing liquid-state relaxation. PMID:22367680

  2. Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: the importance of level crossings.

    PubMed

    Thurber, Kent R; Tycko, Robert

    2012-08-28

    We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T(1e) is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants.

  3. Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: The importance of level crossings

    NASA Astrophysics Data System (ADS)

    Thurber, Kent R.; Tycko, Robert

    2012-08-01

    We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T1e is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants.

  4. Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: the importance of level crossings.

    PubMed

    Thurber, Kent R; Tycko, Robert

    2012-08-28

    We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T(1e) is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants. PMID:22938251

  5. Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: The importance of level crossings

    PubMed Central

    Thurber, Kent R.; Tycko, Robert

    2012-01-01

    We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T1e is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants. PMID:22938251

  6. Backscattering between helical edge states via dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Del Maestro, Adrian; Hyart, Timo; Rosenow, Bernd

    2013-04-01

    We show that the nonequilibrium spin polarization of one-dimensional helical edge states at the boundary of a two-dimensional topological insulator can dynamically induce a polarization of nuclei via the hyperfine interaction. When combined with a spatially inhomogeneous Rashba coupling, the steady-state polarization of the nuclei produces backscattering between the topologically protected edge states leading to a reduction in the conductance which persists to zero temperature. We study these effects in both short and long edges, uncovering deviations from Ohmic transport at finite temperature and a current noise spectrum which may hold the fingerprints for experimental verification of the backscattering mechanism.

  7. IBA-Europhysics Prize in Applied Nuclear Science and Nuclear Methods in Medicine

    NASA Astrophysics Data System (ADS)

    MacGregor, I. J. Douglas

    2014-03-01

    The Nuclear Physics Board of the European Physical Society is pleased to announce that the 2013 IBA-Europhysics Prize in Applied Nuclear Science and Nuclear Methods in Medicine is awarded to Prof. Marco Durante, Director of the Biophysics Department at GSI Helmholtz Center (Darmstadt, Germany); Professor at the Technical University of Darmstadt (Germany) and Adjunct Professor at the Temple University, Philadelphia, USA. The prize was presented in the closing Session of the INPC 2013 conference by Mr. Thomas Servais, R&D Manager for Accelerator Development at the IBA group, who sponsor the IBA Europhysics Prize. The Prize Diploma was presented by Dr. I J Douglas MacGregor, Chair-elect of the EPS Nuclear Physics Division and Chair of the IBA Prize committee.

  8. Theoretical aspects of dynamic nuclear polarization in the solid state - The solid effect

    NASA Astrophysics Data System (ADS)

    Hovav, Yonatan; Feintuch, Akiva; Vega, Shimon

    2010-12-01

    Dynamic nuclear polarization has gained high popularity in recent years, due to advances in the experimental aspects of this methodology for increasing the NMR and MRI signals of relevant chemical and biological compounds. The DNP mechanism relies on the microwave (MW) irradiation induced polarization transfer from unpaired electrons to the nuclei in a sample. In this publication we present nuclear polarization enhancements of model systems in the solid state at high magnetic fields. These results were obtained by numerical calculations based on the spin density operator formalism. Here we restrict ourselves to samples with low electron concentrations, where the dipolar electron-electron interactions can be ignored. Thus the DNP enhancement of the polarizations of the nuclei close to the electrons is described by the Solid Effect mechanism. Our numerical results demonstrate the dependence of the polarization enhancement on the MW irradiation power and frequency, the hyperfine and nuclear dipole-dipole spin interactions, and the relaxation parameters of the system. The largest spin system considered in this study contains one electron and eight nuclei. In particular, we discuss the influence of the nuclear concentration and relaxation on the polarization of the core nuclei, which are coupled to an electron, and are responsible for the transfer of polarization to the bulk nuclei in the sample via spin diffusion.

  9. High-Field Dynamic Nuclear Polarization for Solid and Solution Biological NMR

    PubMed Central

    Barnes, A.B.; Paëpe, G. De; van der Wel, P.C.A.; Hu, K.-N.; Joo, C.-G.; Bajaj, V.S.; Mak-Jurkauskas, M.L.; Sirigiri, J.R.; Herzfeld, J.; Temkin, R.J.; Griffin, R.G.

    2008-01-01

    Dynamic nuclear polarization (DNP) results in a substantial nuclear polarization enhancement through a transfer of the magnetization from electrons to nuclei. Recent years have seen considerable progress in the development of DNP experiments directed towards enhancing sensitivity in biological nuclear magnetic resonance (NMR). This review covers the applications, hardware, polarizing agents, and theoretical descriptions that were developed at the Francis Bitter Magnet Laboratory at Massachusetts Institute of Technology for high-field DNP experiments. In frozen dielectrics, the enhanced nuclear polarization developed in the vicinity of the polarizing agent can be efficiently dispersed to the bulk of the sample via 1H spin diffusion. This strategy has been proven effective in polarizing biologically interesting systems, such as nanocrystalline peptides and membrane proteins, without leading to paramagnetic broadening of the NMR signals. Gyrotrons have been used as a source of high-power (5–10 W) microwaves up to 460 GHz as required for the DNP experiments. Other hardware has also been developed allowing in situ microwave irradiation integrated with cryogenic magic-angle-spinning solid-state NMR. Advances in the quantum mechanical treatment are successful in describing the mechanism by which new biradical polarizing agents yield larger enhancements at higher magnetic fields. Finally, pulsed methods and solution experiments should play a prominent role in the future of DNP. PMID:19194532

  10. Nuclear-polarization correction to the bound-electron g factor in heavy hydrogenlike ions.

    PubMed

    Nefiodov, A V; Plunien, G; Soff, G

    2002-08-19

    The influence of nuclear polarization on the bound-electron g factor in heavy hydrogenlike ions is investigated. Numerical calculations are performed for the K- and L-shell electrons taking into account the dominant virtual nuclear excitations. This determines the ultimate limit for tests of QED utilizing measurements of the bound-electron g factor in highly charged ions.

  11. Comment on "Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage".

    PubMed

    Nakagome, Shigeki; Mano, Shuhei; Hasegawa, Masami

    2013-03-29

    Based on nuclear and mitochondrial DNA, Hailer et al. (Reports, 20 April 2012, p. 344) suggested early divergence of polar bears from a common ancestor with brown bears and subsequent introgression. Our population genetic analysis that traces each of the genealogies in the independent nuclear loci does not support the evolutionary model proposed by the authors.

  12. Nuclear-polarization correction to the bound-electron g factor in heavy hydrogenlike ions.

    PubMed

    Nefiodov, A V; Plunien, G; Soff, G

    2002-08-19

    The influence of nuclear polarization on the bound-electron g factor in heavy hydrogenlike ions is investigated. Numerical calculations are performed for the K- and L-shell electrons taking into account the dominant virtual nuclear excitations. This determines the ultimate limit for tests of QED utilizing measurements of the bound-electron g factor in highly charged ions. PMID:12190457

  13. Strongly polarizing weakly coupled 13C nuclear spins with optically pumped nitrogen-vacancy center

    PubMed Central

    Wang, Ping; Liu, Bao; Yang, Wen

    2015-01-01

    Enhancing the polarization of nuclear spins surrounding the nitrogen-vacancy (NV) center in diamond has recently attracted widespread attention due to its various applications. Here we present an analytical formula that not only provides a clear physical picture for the recently observed polarization reversal of strongly coupled13C nuclei over a narrow range of magnetic field [H. J. Wang et al., Nat. Commun. 4, 1940 (2013)], but also demonstrates the possibility to strongly polarize weakly coupled13C nuclei. This allows sensitive magnetic field control of the 13C nuclear spin polarization for NMR applications and significant suppression of the 13C nuclear spin noise to prolong the NV spin coherence time. PMID:26521962

  14. Comparative study of nuclear effects in polarized electron scattering from 3 He

    DOE PAGES

    Ethier, J. J.; Melnitchouk, W.

    2013-11-01

    We present a detailed analysis of nuclear effects in inclusive electron scattering from polarized 3He nuclei for polarization asymmetries, structure functions and their moments, both in the nucleon resonance and deep-inelastic regions. We compare the results of calculations within the weak binding approximation at finite Q2 with the effective polarization ansatz often used in experimental data analyses, and explore the impact of Δ components in the nuclear wave function and nucleon off-shell corrections on extractions of the free neutron structure. Using the same framework we also make predictions for the Q2 dependence of quasielastic scattering from polarized 3He, data onmore » which can be used to constrain the spin-dependent nuclear smearing functions in 3He.« less

  15. Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials, and organisms.

    PubMed

    Goodson, Boyd M

    2002-04-01

    The sensitivity of conventional nuclear magnetic resonance (NMR) techniques is fundamentally limited by the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This review describes the principles and magnetic resonance applications of laser-polarized noble gases. The enormous sensitivity enhancement afforded by optical pumping can be exploited to permit a variety of novel NMR experiments across numerous disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, NMR sensitivity enhancement via polarization transfer, and low-field NMR and MRI. PMID:12036331

  16. Applying fast calorimetry on a spent nuclear fuel calorimeter

    SciTech Connect

    Liljenfeldt, Henrik

    2015-04-15

    Recently at Los Alamos National Laboratory, sophisticated prediction algorithms have been considered for the use of calorimetry for treaty verification. These algorithms aim to predict the equilibrium temperature based on early data and therefore be able to shorten the measurement time while maintaining good accuracy. The algorithms have been implemented in MATLAB and applied on existing equilibrium measurements from a spent nuclear fuel calorimeter located at the Swedish nuclear fuel interim storage facility. The results show significant improvements in measurement time in the order of 15 to 50 compared to equilibrium measurements, but cannot predict the heat accurately in less time than the currently used temperature increase method can. This Is both due to uncertainties in the calibration of the method as well as identified design features of the calorimeter that limits the usefulness of equilibrium type measurements. The conclusions of these findings are discussed, and suggestions of both improvements of the current calorimeter as well as what to keep in mind in a new design are given.

  17. A high-pressure polarized 3He gas target for nuclear-physics experiments using a polarized photon beam

    NASA Astrophysics Data System (ADS)

    Ye, Q.; Laskaris, G.; Chen, W.; Gao, H.; Zheng, W.; Zong, X.; Averett, T.; Cates, G. D.; Tobias, W. A.

    2010-04-01

    Following the first experiment on three-body photodisintegration of polarized 3He utilizing circularly polarized photons from High-Intensity Gamma Source (HI γ S) at Duke Free Electron Laser Laboratory (DFELL), a new high-pressure polarized 3He target cell made of pyrex glass coated with a thin layer of sol-gel doped with aluminum nitrate nonahydrate has been built in order to reduce the photon beam-induced background. The target is based on the technique of spin exchange optical pumping of hybrid rubidium and potassium and the highest polarization achieved is ˜ 62% determined from both NMR-AFP and EPR polarimetries. The phenomenological parameter that reflects the additional unknown spin relaxation processes, X , is estimated to be ˜ 0.10 and the performance of the target is in good agreement with theoretical predictions. We also present beam test results from this new target cell and the comparison with the GE180 3He target cell used previously at HI γ S. This is the first time that the sol-gel coating technique has been used in a polarized 3He target for nuclear-physics experiments.

  18. Precision measurement of the nuclear polarization in laser-cooled, optically pumped 37K

    NASA Astrophysics Data System (ADS)

    Fenker, B.; Behr, J. A.; Melconian, D.; Anderson, R. M. A.; Anholm, M.; Ashery, D.; Behling, R. S.; Cohen, I.; Craiciu, I.; Donohue, J. M.; Farfan, C.; Friesen, D.; Gorelov, A.; McNeil, J.; Mehlman, M.; Norton, H.; Olchanski, K.; Smale, S.; Thériault, O.; Vantyghem, A. N.; Warner, C. L.

    2016-07-01

    We report a measurement of the nuclear polarization of laser-cooled, optically pumped 37K atoms which will allow us to precisely measure angular correlation parameters in the {β }+-decay of the same atoms. These results will be used to test the V - A framework of the weak interaction at high precision. At the Triumf neutral atom trap (Trinat), a magneto-optical trap confines and cools neutral 37K atoms and optical pumping spin-polarizes them. We monitor the nuclear polarization of the same atoms that are decaying in situ by photoionizing a small fraction of the partially polarized atoms and then use the standard optical Bloch equations to model their population distribution. We obtain an average nuclear polarization of \\bar{P}=0.9913+/- 0.0009, which is significantly more precise than previous measurements with this technique. Since our current measurement of the β-asymmetry has 0.2 % statistical uncertainty, the polarization measurement reported here will not limit its overall uncertainty. This result also demonstrates the capability to measure the polarization to \\lt 0.1 % , allowing for a measurement of angular correlation parameters to this level of precision, which would be competitive in searches for new physics.

  19. Application of blind source separation to real-time dissolution dynamic nuclear polarization.

    PubMed

    Hilty, Christian; Ragavan, Mukundan

    2015-01-20

    The use of a blind source separation (BSS) algorithm is demonstrated for the analysis of time series of nuclear magnetic resonance (NMR) spectra. This type of data is obtained commonly from experiments, where analytes are hyperpolarized using dissolution dynamic nuclear polarization (D-DNP), both in in vivo and in vitro contexts. High signal gains in D-DNP enable rapid measurement of data sets characterizing the time evolution of chemical or metabolic processes. BSS is based on an algorithm that can be applied to separate the different components contributing to the NMR signal and determine the time dependence of the signals from these components. This algorithm requires minimal prior knowledge of the data, notably, no reference spectra need to be provided, and can therefore be applied rapidly. In a time-resolved measurement of the enzymatic conversion of hyperpolarized oxaloacetate to malate, the two signal components are separated into computed source spectra that closely resemble the spectra of the individual compounds. An improvement in the signal-to-noise ratio of the computed source spectra is found compared to the original spectra, presumably resulting from the presence of each signal more than once in the time series. The reconstruction of the original spectra yields the time evolution of the contributions from the two sources, which also corresponds closely to the time evolution of integrated signal intensities from the original spectra. BSS may therefore be an approach for the efficient identification of components and estimation of kinetics in D-DNP experiments, which can be applied at a high level of automation. PMID:25506716

  20. Application of blind source separation to real-time dissolution dynamic nuclear polarization.

    PubMed

    Hilty, Christian; Ragavan, Mukundan

    2015-01-20

    The use of a blind source separation (BSS) algorithm is demonstrated for the analysis of time series of nuclear magnetic resonance (NMR) spectra. This type of data is obtained commonly from experiments, where analytes are hyperpolarized using dissolution dynamic nuclear polarization (D-DNP), both in in vivo and in vitro contexts. High signal gains in D-DNP enable rapid measurement of data sets characterizing the time evolution of chemical or metabolic processes. BSS is based on an algorithm that can be applied to separate the different components contributing to the NMR signal and determine the time dependence of the signals from these components. This algorithm requires minimal prior knowledge of the data, notably, no reference spectra need to be provided, and can therefore be applied rapidly. In a time-resolved measurement of the enzymatic conversion of hyperpolarized oxaloacetate to malate, the two signal components are separated into computed source spectra that closely resemble the spectra of the individual compounds. An improvement in the signal-to-noise ratio of the computed source spectra is found compared to the original spectra, presumably resulting from the presence of each signal more than once in the time series. The reconstruction of the original spectra yields the time evolution of the contributions from the two sources, which also corresponds closely to the time evolution of integrated signal intensities from the original spectra. BSS may therefore be an approach for the efficient identification of components and estimation of kinetics in D-DNP experiments, which can be applied at a high level of automation.

  1. Resonance-inclined optical nuclear spin polarization of liquids in diamond structures

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Schwarz, I.; Jelezko, F.; Retzker, A.; Plenio, M. B.

    2016-02-01

    Dynamic nuclear polarization (DNP) of molecules in a solution at room temperature has the potential to revolutionize nuclear magnetic resonance spectroscopy and imaging. The prevalent methods for achieving DNP in solutions are typically most effective in the regime of small interaction correlation times between the electron and nuclear spins, limiting the size of accessible molecules. To solve this limitation, we design a mechanism for DNP in the liquid phase that is applicable for large interaction correlation times. Importantly, while this mechanism makes use of a resonance condition similar to solid-state DNP, the polarization transfer is robust to a relatively large detuning from the resonance due to molecular motion. We combine this scheme with optically polarized nitrogen-vacancy (NV) center spins in nanodiamonds to design a setup that employs optical pumping and is therefore not limited by room temperature electron thermal polarization. We illustrate numerically the effectiveness of the model in a flow cell containing nanodiamonds immobilized in a hydrogel, polarizing flowing water molecules 4700-fold above thermal polarization in a magnetic field of 0.35 T, in volumes detectable by current NMR scanners.

  2. Dynamic nuclear polarization assisted spin diffusion for the solid effect case

    NASA Astrophysics Data System (ADS)

    Hovav, Yonatan; Feintuch, Akiva; Vega, Shimon

    2011-02-01

    The dynamic nuclear polarization (DNP) process in solids depends on the magnitudes of hyperfine interactions between unpaired electrons and their neighboring (core) nuclei, and on the dipole-dipole interactions between all nuclei in the sample. The polarization enhancement of the bulk nuclei has been typically described in terms of a hyperfine-assisted polarization of a core nucleus by microwave irradiation followed by a dipolar-assisted spin diffusion process in the core-bulk nuclear system. This work presents a theoretical approach for the study of this combined process using a density matrix formalism. In particular, solid effect DNP on a single electron coupled to a nuclear spin system is considered, taking into account the interactions between the spins as well as the main relaxation mechanisms introduced via the electron, nuclear, and cross-relaxation rates. The basic principles of the DNP-assisted spin diffusion mechanism, polarizing the bulk nuclei, are presented, and it is shown that the polarization of the core nuclei and the spin diffusion process should not be treated separately. To emphasize this observation the coherent mechanism driving the pure spin diffusion process is also discussed. In order to demonstrate the effects of the interactions and relaxation mechanisms on the enhancement of the nuclear polarization, model systems of up to ten spins are considered and polarization buildup curves are simulated. A linear chain of spins consisting of a single electron coupled to a core nucleus, which in turn is dipolar coupled to a chain of bulk nuclei, is considered. The interaction and relaxation parameters of this model system were chosen in a way to enable a critical analysis of the polarization enhancement of all nuclei, and are not far from the values of 13C nuclei in frozen (glassy) organic solutions containing radicals, typically used in DNP at high fields. Results from the simulations are shown, demonstrating the complex dependences of the DNP

  3. Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage.

    PubMed

    Hailer, Frank; Kutschera, Verena E; Hallström, Björn M; Klassert, Denise; Fain, Steven R; Leonard, Jennifer A; Arnason, Ulfur; Janke, Axel

    2012-04-20

    Recent studies have shown that the polar bear matriline (mitochondrial DNA) evolved from a brown bear lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears. Bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle Pleistocene, about 600 (338 to 934) thousand years ago. This provides more time for polar bear evolution and confirms previous suggestions that polar bears carry introgressed brown bear mitochondrial DNA due to past hybridization. Our results highlight that multilocus genomic analyses are crucial for an accurate understanding of evolutionary history.

  4. Recursive polarization of nuclear spins in diamond at arbitrary magnetic fields

    SciTech Connect

    Pagliero, Daniela; Laraoui, Abdelghani; Henshaw, Jacob D.; Meriles, Carlos A.

    2014-12-15

    We introduce an alternate route to dynamically polarize the nuclear spin host of nitrogen-vacancy (NV) centers in diamond. Our approach articulates optical, microwave, and radio-frequency pulses to recursively transfer spin polarization from the NV electronic spin. Using two complementary variants of the same underlying principle, we demonstrate nitrogen nuclear spin initialization approaching 80% at room temperature both in ensemble and single NV centers. Unlike existing schemes, our approach does not rely on level anti-crossings and is thus applicable at arbitrary magnetic fields. This versatility should prove useful in applications ranging from nanoscale metrology to sensitivity-enhanced NMR.

  5. Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials and organisms

    SciTech Connect

    Goodson, Boyd M.

    1999-12-01

    Conventional nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) are fundamentally challenged by the insensitivity that stems from the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This dissertation is primarily concerned with the principles and practice of optically pumped nuclear magnetic resonance (OPNMR). The enormous sensitivity enhancement afforded by optical pumping noble gases can be exploited to permit a variety of novel NMR experiments across many disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, and zero-field NMR and MRI.

  6. Thermalization and many-body localization in systems under dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    De Luca, Andrea; Rodríguez-Arias, Inés; Müller, Markus; Rosso, Alberto

    2016-07-01

    We study the role of dipolar interactions in the standard protocol used to achieve dynamic nuclear polarization (DNP). We point out that a critical strength of interactions is required to obtain significant nuclear hyperpolarization. Otherwise, the electron spins do not thermalize among each other, due to the incipient many-body localization transition in the electron spin system. Only when the interactions are sufficiently strong, in the so-called spin-temperature regime, they establish an effective thermodynamic behavior in the out-of-equilibrium stationary state. The highest polarization is reached at a point where the spin temperature is just not able to establish itself anymore. We provide numerical predictions for the level of nuclear hyperpolarization and present an analytical technique to estimate the spin temperature as a function of interaction strength and quenched disorder. We show that, at sufficiently strong coupling, nuclear spins perfectly equilibrate to the spin temperature that establishes among the spins of radicals.

  7. Dynamic nuclear polarization solid-state NMR in heterogeneous catalysis research

    SciTech Connect

    Kobayashi, Takeshi; Perras, Frédéric A.; Slowing, Igor I.; Sadow, Aaron D.; Pruski, Marek

    2015-10-20

    In this study, a revolution in solid-state nuclear magnetic resonance (SSNMR) spectroscopy is taking place, attributable to the rapid development of high-field dynamic nuclear polarization (DNP), a technique yielding sensitivity improvements of 2–3 orders of magnitude. This higher sensitivity in SSNMR has already impacted materials research, and the implications of new methods on catalytic sciences are expected to be profound.

  8. Dynamic nuclear polarization solid-state NMR in heterogeneous catalysis research

    DOE PAGES

    Kobayashi, Takeshi; Perras, Frédéric A.; Slowing, Igor I.; Sadow, Aaron D.; Pruski, Marek

    2015-10-20

    In this study, a revolution in solid-state nuclear magnetic resonance (SSNMR) spectroscopy is taking place, attributable to the rapid development of high-field dynamic nuclear polarization (DNP), a technique yielding sensitivity improvements of 2–3 orders of magnitude. This higher sensitivity in SSNMR has already impacted materials research, and the implications of new methods on catalytic sciences are expected to be profound.

  9. Topical Developments in High-Field Dynamic Nuclear Polarization

    PubMed Central

    Kiesewetter, Matthew K.; Frantz, Derik K.; Walish, Joseph J.; Ravera, Enrico; Luchinat, Claudio; Swager, Timothy M.; Griffin, Robert G.

    2015-01-01

    We report our recent efforts directed at improving high-field DNP experiments. We investigated a series of thiourea nitroxide radicals and the associated DNP enhancements ranging from ε = 25 to 82 that demonstrate the impact of molecular structure on performance. We directly polarized low-gamma nuclei including 13C, 2H, and 17O using trityl via the cross effect. We discuss a variety of sample preparation techniques for DNP with emphasis on the benefit of methods that do not use a glass-forming cryoprotecting matrix. Lastly, we describe a corrugated waveguide for use in a 700 MHz / 460 GHz DNP system that improves microwave delivery and increases enhancements up to 50%. PMID:25977588

  10. Applying laser technology to decommissioning for nuclear power plant

    NASA Astrophysics Data System (ADS)

    Saishu, Sadanori; Abe, Seiji; Inoue, T.

    2000-01-01

    Laser technology has much possibility to accomplish nuclear facility decommissioning effective and the laser application to cutting technique and decontamination technique is considered in Japan. Nuclear Power Engineering Corporation had developed CO laser for cutting technique, and had developed YAG laser for decontamination.

  11. Experimental demonstration of a stimulated polarization wave in a chain of nuclear spins

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Seung; Adams, Travis; Khitrin, A. K.

    2007-04-01

    A stimulated wave of polarization, which implements a simple mechanism of quantum amplification, is experimentally demonstrated in a chain of four J-coupled nuclear spins, irradiated by a weak radio-frequency transverse field. The 'quantum domino' dynamics, a wave of flipped spins triggered by a flip of the first spin, has been observed in fully 13C-labelled sodium butyrate.

  12. Formulation and utilization of choline based samples for dissolution dynamic nuclear polarization.

    PubMed

    Bowen, Sean; Ardenkjaer-Larsen, Jan Henrik

    2013-11-01

    Hyperpolarization by the dissolution dynamic nuclear polarization (DNP) technique permits the generation of high spin polarization of solution state. However, sample formulation for dissolution-DNP is often difficult, as concentration and viscosity must be optimized to yield a dissolved sample with sufficient concentration, while maintaining polarization during the dissolution process. The unique chemical properties of choline permit the generation of highly soluble salts as well as deep eutectic mixtures with carboxylic acids and urea. We describe the formulation of these samples and compare their performance to more traditional sample formulations. Choline yields stable samples with exceptional polarization performance while simultaneously offering the capability to easily remove the choline after dissolution, perform experiments with the hyperpolarized choline, or anything in between. PMID:24036470

  13. Formulation and utilization of choline based samples for dissolution dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Bowen, Sean; Ardenkjaer-Larsen, Jan Henrik

    2013-11-01

    Hyperpolarization by the dissolution dynamic nuclear polarization (DNP) technique permits the generation of high spin polarization of solution state. However, sample formulation for dissolution-DNP is often difficult, as concentration and viscosity must be optimized to yield a dissolved sample with sufficient concentration, while maintaining polarization during the dissolution process. The unique chemical properties of choline permit the generation of highly soluble salts as well as deep eutectic mixtures with carboxylic acids and urea. We describe the formulation of these samples and compare their performance to more traditional sample formulations. Choline yields stable samples with exceptional polarization performance while simultaneously offering the capability to easily remove the choline after dissolution, perform experiments with the hyperpolarized choline, or anything in between.

  14. Predicting the future distribution of Polar Bear Habitat in the polar basin from resource selection functions applied to 21st century general circulation model projections of sea ice

    USGS Publications Warehouse

    Durner, George M.; Douglas, David C.; Nielson, Ryan M.; Amstrup, Steven C.; McDonald, Trent L.

    2007-01-01

    Predictions of polar bear (Ursus maritimus) habitat distribution in the Arctic polar basin during the 21st century were developed to help understand the likely consequences of anticipated sea ice reductions on polar bear populations. We used location data from satellite-collared polar bears and environmental data (e.g., bathymetry, coastlines, and sea ice) collected between 1985–1995 to build habitat use models called Resource Selection Functions (RSF). The RSFs described habitats polar bears preferred in each of four seasons: summer (ice minimum), autumn (growth), winter (ice maximum) and spring (melt). When applied to the model source data and to independent data (1996–2006), the RSFs consistently identified habitats most frequently used by polar bears. We applied the RSFs to monthly maps of 21st century sea ice concentration predicted by 10 general circulation models (GCM) described in the International Panel of Climate Change Fourth Assessment Report. The 10 GCMs we used had high concordance between their simulations of 20th century summer sea ice extent and the actual ice extent derived from passive microwave satellite observations. Predictions of the amount and rate of change in polar bear habitat varied among GCMs, but all GCMs predicted net habitat losses in the polar basin during the 21st century. Projected losses in the highest-valued RSF habitat (optimal habitat) were greatest in the peripheral seas of the polar basin, especially the Chukchi Sea and Barents Sea. Losses were least in high-latitude regions where RSFs predicted an initial increase in optimal habitat followed by a modest decline. The largest seasonal reductions in habitat were predicted for spring and summer. Average area of optimal polar bear habitat during summer in the polar basin declined from an observed 1.0 million km2 in 1985–1995 (baseline) to a projected multi-model average of 0.58 million km2 in 2045–2054 (-42% change), 0.36 million km2 in 2070–2079 (-64% change), and 0

  15. Dynamic Nuclear Polarization in Samarium Doped Lanthanum Magnesium Nitrate. Ph.D. Thesis - Va. Polytechnic Inst.

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.

    1971-01-01

    The dynamic nuclear polarization of hydrogen nuclei by the solid effect in single crystals of samarium doped lanthanum magnesium nitrate (Sm:LMN) was studied theoretically and experimentally. The equations of evolution governing the dynamic nuclear polarization by the solid effect were derived in detail using the spin temperature theory and the complete expression for the steady state enhancement of the nuclear polarization was calculated. Experimental enhancements of the proton polarization were obtained for eight crystals at 9.2 GHz and liquid helium temperatures. The samarium concentration ranged from 0.1 percent to 1.1 percent as determined by X-ray fluorescence. A peak enhancement of 181 was measured for a 1.1 percent Sm:LMN crystal at 3.0 K. The maximum enhancements extrapolated with the theory using the experimental data for peak enhancement versus microwave power and correcting for leakage, agree with the ideal enhancement (240 in this experiment) within experimental error for three of the crystals.

  16. Solid-state dynamic nuclear polarization at 263 GHz: spectrometer design and experimental results†

    PubMed Central

    Rosay, Melanie; Tometich, Leo; Pawsey, Shane; Bader, Reto; Schauwecker, Robert; Blank, Monica; Borchard, Philipp M.; Cauffman, Stephen R.; Felch, Kevin L.; Weber, Ralph T.; Temkin, Richard J.; Griffin, Robert G.; Maas, Werner E.

    2015-01-01

    Dynamic Nuclear Polarization (DNP) experiments transfer polarization from electron spins to nuclear spins with microwave irradiation of the electron spins for enhanced sensitivity in nuclear magnetic resonance (NMR) spectroscopy. Design and testing of a spectrometer for magic angle spinning (MAS) DNP experiments at 263 GHz microwave frequency, 400 MHz 1H frequency is described. Microwaves are generated by a novel continuous-wave gyrotron, transmitted to the NMR probe via a transmission line, and irradiated on a 3.2 mm rotor for MAS DNP experiments. DNP signal enhancements of up to 80 have been measured at 95 K on urea and proline in water–glycerol with the biradical polarizing agent TOTAPOL. We characterize the experimental parameters affecting the DNP efficiency: the magnetic field dependence, temperature dependence and polarization build-up times, microwave power dependence, sample heating effects, and spinning frequency dependence of the DNP signal enhancement. Stable system operation, including DNP performance, is also demonstrated over a 36 h period. PMID:20449524

  17. The nuclear frontier; Cornell's program of basic and applied research

    SciTech Connect

    Clark, D.D. . Dept. of Nuclear Science and Engineering)

    1992-01-01

    This paper discusses the Program in Nuclear Science and Engineering at Cornell, an interdisciplinary field that encompasses a wide range of research. Some faculty members and graduate students are working on the basic physics of nuclei, plasmas, and atoms, while other are investigating the interaction of radiation with matter and the basic mechanisms of radiation-induced failure in microelectronic devices. Some are developing new research techniques based on nuclear and atomic interactions, and others are adapting nuclear methods such as activation analysis to research in geology, biology, and archaeology. Some are investigating advanced types of ion and electron beams, while yet others are improving the generation of power from fission and seeking to generate it from fusion.

  18. Nuclear Lamin A/C Deficiency Induces Defects in Cell Mechanics, Polarization, and Migration

    PubMed Central

    Lee, Jerry S. H.; Hale, Christopher M.; Panorchan, Porntula; Khatau, Shyam B.; George, Jerry P.; Tseng, Yiider; Stewart, Colin L.; Hodzic, Didier; Wirtz, Denis

    2007-01-01

    Lamin A/C is a major constituent of the nuclear lamina, a thin filamentous protein layer that lies beneath the nuclear envelope. Here we show that lamin A/C deficiency in mouse embryonic fibroblasts (Lmna−/− MEFs) diminishes the ability of these cells to polarize at the edge of a wound and significantly reduces cell migration speed into the wound. Moreover, lamin A/C deficiency induces significant separation of the microtubule organizing center (MTOC) from the nuclear envelope. Investigations using ballistic intracellular nanorheology reveal that lamin A/C deficiency also dramatically affects the micromechanical properties of the cytoplasm. Both the elasticity (stretchiness) and the viscosity (propensity of a material to flow) of the cytoplasm in Lmna−/− MEFs are significantly reduced. Disassembly of either the actin filament or microtubule networks in Lmna+/+ MEFs results in decrease of cytoplasmic elasticity and viscosity down to levels found in Lmna−/− MEFs. Together these results show that both the mechanical properties of the cytoskeleton and cytoskeleton-based processes, including cell motility, coupled MTOC and nucleus dynamics, and cell polarization, depend critically on the integrity of the nuclear lamina, which suggest the existence of a functional mechanical connection between the nucleus and the cytoskeleton. These results also suggest that cell polarization during cell migration requires tight mechanical coupling between MTOC and nucleus, which is mediated by lamin A/C. PMID:17631533

  19. Polarization and Color Filtering Applied to Enhance Photogrammetric Measurements of Reflective Surfaces

    NASA Technical Reports Server (NTRS)

    Wells, Jeffrey M.; Jones, Thomas W.; Danehy, Paul M.

    2005-01-01

    Techniques for enhancing photogrammetric measurement of reflective surfaces by reducing noise were developed utilizing principles of light polarization. Signal selectivity with polarized light was also compared to signal selectivity using chromatic filters. Combining principles of linear cross polarization and color selectivity enhanced signal-to-noise ratios by as much as 800 fold. More typical improvements with combining polarization and color selectivity were about 100 fold. We review polarization-based techniques and present experimental results comparing the performance of traditional retroreflective targeting materials, cornercube targets returning depolarized light, and color selectivity.

  20. Labelled compounds and radiopharmaceuticals applied in nuclear medicine

    SciTech Connect

    Balaban, A.; Galateanu, I.; Geogescu, G.; Simionescu, L.

    1986-01-01

    This book includes material on radiopharmacy and nuclear medicine with a section on in vitro assays. Contents are divided into four parts: radioisotopes, labelled compounds and radiopharmaceuticals; radiopharmaceuticals used for diagnostic purposes; in vitro methods of analysis with labelled compounds and applications of radioimmunoassay to medicine.

  1. Tailoring of Polarizing Agents in the bTurea Series for Cross-Effect Dynamic Nuclear Polarization in Aqueous Media.

    PubMed

    Sauvée, Claire; Casano, Gilles; Abel, Sébastien; Rockenbauer, Antal; Akhmetzyanov, Dimitry; Karoui, Hakim; Siri, Didier; Aussenac, Fabien; Maas, Werner; Weber, Ralph T; Prisner, Thomas; Rosay, Mélanie; Tordo, Paul; Ouari, Olivier

    2016-04-11

    A series of 18 nitroxide biradicals derived from bTurea has been prepared, and their enhancement factors ɛ ((1)H) in cross-effect dynamic nuclear polarization (CE DNP) NMR experiments at 9.4 and 14.1 T and 100 K in a DNP-optimized glycerol/water matrix ("DNP juice") have been studied. We observe that ɛ ((1)H) is strongly correlated with the substituents on the polarizing agents, and its trend is discussed in terms of different molecular parameters: solubility, average e-e distance, relative orientation of the nitroxide moieties, and electron spin relaxation times. We show that too short an e-e distance or too long a T1e can dramatically limit ɛ ((1)H). Our study also shows that the molecular structure of AMUPol is not optimal and its ɛ ((1)H) could be further improved through stronger interaction with the glassy matrix and a better orientation of the TEMPO moieties. A new AMUPol derivative introduced here provides a better ɛ ((1)H) than AMUPol itself (by a factor of ca. 1.2). PMID:26992052

  2. Investigation of a new model of dipolar-coupled nuclear spin relaxation and applications of dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Sorte, Eric G.

    This work presents the results of various investigations using various techniques of hyperpolarizing the nuclei of atoms. Hyperpolarization implies magnetic order in excess of the thermal order obtained naturally as described by Curie's law. The main portion of this work presents the results of a detailed experimental exploration of predictions arising from a new model of transverse nuclear spin relaxation in quantum systems, based on possible manifestations of microscopic chaos in quantum systems. Experiments have been carried out on a number of hyperpolarized xenon samples, each differing in its relative percentage of xenon isotopes in order to vary the homonuclear and heteronuclear dipole couplings in the spin system. The experiments were performed under a variety of conditions in an attempt to observe the behaviors predicted by the model. Additionally, much more extensive measurements were made on a number of samples of solid CaF2 in both single crystal and powder forms. These samples, although thermally polarized, were observed with superior signal to noise ratios than even the hyperpolarized xenon solids, allowing for more precise measurements for comparison to the theory. This work thus contains the first experimental evidence for the majority of the model's predictions. Additionally, this work contains the first precise measurements of the frequency-shift enhancement parameters for 129Xe and krypton in the presence of spin-polarized Rb. The determination of these important numbers will be useful to many groups who utilize spin-exchange optical pumping in their labs. This work built on the prior knowledge of a precise number for the frequency-shift enhancement parameter of 3He in Rb vapor. Finally, I detail work using NMR to detect nuclear-spin polarization enhancement in silicon phosphorus by a novel, photo-induced hyperpolarization technique developed by the Boehme research group at the University of Utah. Significant nuclear polarization enhancements were

  3. Dynamic nuclear polarization by frequency modulation of a tunable gyrotron of 260 GHz

    NASA Astrophysics Data System (ADS)

    Yoon, Dongyoung; Soundararajan, Murari; Cuanillon, Philippe; Braunmueller, Falk; Alberti, Stefano; Ansermet, Jean-Philippe

    2016-01-01

    An increase in Dynamic Nuclear Polarization (DNP) signal intensity is obtained with a tunable gyrotron producing frequency modulation around 260 GHz at power levels less than 1 W. The sweep rate of frequency modulation can reach 14 kHz, and its amplitude is fixed at 50 MHz. In water/glycerol glassy ice doped with 40 mM TEMPOL, the relative increase in the DNP enhancement was obtained as a function of frequency-sweep rate for several temperatures. A 68 % increase was obtained at 15 K, thus giving a DNP enhancement of about 80. By employing λ / 4 and λ / 8 polarizer mirrors, we transformed the polarization of the microwave beam from linear to circular, and achieved an increase in the enhancement by a factor of about 66% for a given power.

  4. Measuring surface-area-to-volume ratios in soft porous materials using laser-polarized xenon interphase exchange nuclear magnetic resonance

    NASA Technical Reports Server (NTRS)

    Butler, J. P.; Mair, R. W.; Hoffmann, D.; Hrovat, M. I.; Rogers, R. A.; Topulos, G. P.; Walsworth, R. L.; Patz, S.

    2002-01-01

    We demonstrate a minimally invasive nuclear magnetic resonance (NMR) technique that enables determination of the surface-area-to-volume ratio (S/V) of soft porous materials from measurements of the diffusive exchange of laser-polarized 129Xe between gas in the pore space and 129Xe dissolved in the solid phase. We apply this NMR technique to porous polymer samples and find approximate agreement with destructive stereological measurements of S/V obtained with optical confocal microscopy. Potential applications of laser-polarized xenon interphase exchange NMR include measurements of in vivo lung function in humans and characterization of gas chromatography columns.

  5. High-field Overhauser dynamic nuclear polarization in silicon below the metal-insulator transition.

    PubMed

    Dementyev, Anatoly E; Cory, David G; Ramanathan, Chandrasekhar

    2011-04-21

    Single crystal silicon is an excellent system to explore dynamic nuclear polarization (DNP), as it exhibits a continuum of properties from metallic to insulating as a function of doping concentration and temperature. At low doping concentrations DNP has been observed to occur via the solid effect, while at very high-doping concentrations an Overhauser mechanism is responsible. Here we report the hyperpolarization of (29)Si in n-doped silicon crystals, with doping concentrations in the range of (1-3) × 10(17) cm(-3). In this regime exchange interactions between donors become extremely important. The sign of the enhancement in our experiments and its frequency dependence suggest that the (29)Si spins are directly polarized by donor electrons via an Overhauser mechanism within exchange-coupled donor clusters. The exchange interaction between donors only needs to be larger than the silicon hyperfine interaction (typically much smaller than the donor hyperfine coupling) to enable this Overhauser mechanism. Nuclear polarization enhancement is observed for a range of donor clusters in which the exchange energy is comparable to the donor hyperfine interaction. The DNP dynamics are characterized by a single exponential time constant that depends on the microwave power, indicating that the Overhauser mechanism is a rate-limiting step. Since only about 2% of the silicon nuclei are located within 1 Bohr radius of the donor electron, nuclear spin diffusion is important in transferring the polarization to all the spins. However, the spin-diffusion time is much shorter than the Overhauser time due to the relatively weak silicon hyperfine coupling strength. In a 2.35 T magnetic field at 1.1 K, we observed a DNP enhancement of 244 ± 84 resulting in a silicon polarization of 10.4 ± 3.4% following 2 h of microwave irradiation.

  6. Chemical Nuclear Polarization of Biradicals Created by Photolysis of Cyclic Aliphatic Ketones in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Obynochnyia, A. A.; Purtovb, P. A.; Salikhova, K. M.

    2008-02-01

    Chemical nuclear polarization (CNP) of short-lived biradicals created in the photolysis of cyclic ketones in the gas phase with a buffer gas of CDCl3 molecules was studied theoretically and experimentally. The magnetoresonance and kinetic parameters were proposed for the biradicals. The experimental fact that the CNP of cycloundecanone in the gas phase and liquid was the strongest was confirmed by calculations. The computational results agree well with the experiment for both gas and liquid phases.

  7. Implementation of polarization processes in a charge transport model applied on poly(ethylene naphthalate) films

    NASA Astrophysics Data System (ADS)

    Hoang, M.-Q.; Le Roy, S.; Boudou, L.; Teyssedre, G.

    2016-06-01

    One of the difficulties in unravelling transport processes in electrically insulating materials is the fact that the response, notably charging current transients, can have mixed contributions from orientation polarization and from space charge processes. This work aims at identifying and characterizing the polarization processes in a polar polymer in the time and frequency-domains and to implement the contribution of the polarization into a charge transport model. To do so, Alternate Polarization Current (APC) and Dielectric Spectroscopy measurements have been performed on poly(ethylene naphthalene 2,6-dicarboxylate) (PEN), an aromatic polar polymer, providing information on polarization mechanisms in the time- and frequency-domain, respectively. In the frequency-domain, PEN exhibits 3 relaxation processes termed β, β* (sub-glass transitions), and α relaxations (glass transition) in increasing order of temperature. Conduction was also detected at high temperatures. Dielectric responses were treated using a simplified version of the Havriliak-Negami model (Cole-Cole (CC) model), using 3 parameters per relaxation process, these parameters being temperature dependent. The time dependent polarization obtained from the CC model is then added to a charge transport model. Simulated currents issued from the transport model implemented with the polarization are compared with the measured APCs, showing a good consistency between experiments and simulations in a situation where the response comes essentially from dipolar processes.

  8. Optimization of 13C dynamic nuclear polarization: isotopic labeling of free radicals

    NASA Astrophysics Data System (ADS)

    Niedbalski, Peter; Parish, Christopher; Kiswandi, Andhika; Lumata, Lloyd

    Dynamic nuclear polarization (DNP) is a physics technique that amplifies the nuclear magnetic resonance (NMR) signals by transferring the high polarization of the electrons to the nuclear spins. Thus, the choice of free radical is crucial in DNP as it can directly affect the NMR signal enhancement levels, typically on the order of several thousand-fold in the liquid-state. In this study, we have investigated the efficiency of four variants of the well-known 4-oxo-TEMPO radical (normal 4-oxo-TEMPO plus its 15N-enriched and/or perdeuterated variants) for use in DNP of an important metabolic tracer [1-13C]acetate. Though the variants have significant differences in electron paramagnetic resonance (EPR) spectra, we have found that changing the composition of the TEMPO radical through deuteration or 15N doping yields no significant difference in 13C DNP efficiency at 3.35 T and 1.2 K. On the other hand, deuteration of the solvent causes a significant increase of 13C polarization that is consistent over all the 4-oxo-TEMPO variants. These findings are consistent with the thermal mixing model of DNP. This work is supported by US Dept of Defense Award No. W81XWH-14-1-0048 and the Robert A. Welch Foundation Grant No. AT-1877.

  9. Reverse micelles as a platform for dynamic nuclear polarization in solution NMR of proteins.

    PubMed

    Valentine, Kathleen G; Mathies, Guinevere; Bédard, Sabrina; Nucci, Nathaniel V; Dodevski, Igor; Stetz, Matthew A; Can, Thach V; Griffin, Robert G; Wand, A Joshua

    2014-02-19

    Despite tremendous advances in recent years, solution NMR remains fundamentally restricted due to its inherent insensitivity. Dynamic nuclear polarization (DNP) potentially offers significant improvements in this respect. The basic DNP strategy is to irradiate the EPR transitions of a stable radical and transfer this nonequilibrium polarization to the hydrogen spins of water, which will in turn transfer polarization to the hydrogens of the macromolecule. Unfortunately, these EPR transitions lie in the microwave range of the electromagnetic spectrum where bulk water absorbs strongly, often resulting in catastrophic heating. Furthermore, the residence times of water on the surface of the protein in bulk solution are generally too short for efficient transfer of polarization. Here we take advantage of the properties of solutions of encapsulated proteins dissolved in low viscosity solvents to implement DNP in liquids. Such samples are largely transparent to the microwave frequencies required and thereby avoid significant heating. Nitroxide radicals are introduced into the reverse micelle system in three ways: attached to the protein, embedded in the reverse micelle shell, and free in the aqueous core. Significant enhancements of the water resonance ranging up to ∼-93 at 0.35 T were observed. We also find that the hydration properties of encapsulated proteins allow for efficient polarization transfer from water to the protein. These and other observations suggest that merging reverse micelle encapsulation technology with DNP offers a route to a significant increase in the sensitivity of solution NMR spectroscopy of proteins and other biomolecules.

  10. Reverse Micelles As a Platform for Dynamic Nuclear Polarization in Solution NMR of Proteins

    PubMed Central

    2015-01-01

    Despite tremendous advances in recent years, solution NMR remains fundamentally restricted due to its inherent insensitivity. Dynamic nuclear polarization (DNP) potentially offers significant improvements in this respect. The basic DNP strategy is to irradiate the EPR transitions of a stable radical and transfer this nonequilibrium polarization to the hydrogen spins of water, which will in turn transfer polarization to the hydrogens of the macromolecule. Unfortunately, these EPR transitions lie in the microwave range of the electromagnetic spectrum where bulk water absorbs strongly, often resulting in catastrophic heating. Furthermore, the residence times of water on the surface of the protein in bulk solution are generally too short for efficient transfer of polarization. Here we take advantage of the properties of solutions of encapsulated proteins dissolved in low viscosity solvents to implement DNP in liquids. Such samples are largely transparent to the microwave frequencies required and thereby avoid significant heating. Nitroxide radicals are introduced into the reverse micelle system in three ways: attached to the protein, embedded in the reverse micelle shell, and free in the aqueous core. Significant enhancements of the water resonance ranging up to ∼−93 at 0.35 T were observed. We also find that the hydration properties of encapsulated proteins allow for efficient polarization transfer from water to the protein. These and other observations suggest that merging reverse micelle encapsulation technology with DNP offers a route to a significant increase in the sensitivity of solution NMR spectroscopy of proteins and other biomolecules. PMID:24456213

  11. Fractional exclusion statistics applied to relativistic nuclear matter

    NASA Astrophysics Data System (ADS)

    Anghel, D. V.; Parvan, A. S.; Khvorostukhin, A. S.

    2012-04-01

    The effect of statistics of the quasiparticles in the nuclear matter at extreme conditions of density and temperature is evaluated in the relativistic mean-field model generalized to the framework of the fractional exclusion statistics (FES). In the model, the nucleons are described as quasiparticles obeying FES and the model parameters were chosen to reproduce the ground state properties of the isospin-symmetric nuclear matter. In this case, the statistics of the quasiparticles is related to the strengths of the nucleon-nucleon interaction mediated by the neutral scalar and vector meson fields. The relevant thermodynamic quantities were calculated as functions of the nucleons density, temperature and fractional exclusion statistics parameter α. It has been shown that at high temperatures and densities the thermodynamics of the system has a strong dependence on the statistics of the particles. The scenario in which the nucleon-nucleon interaction strength is independent of the statistics of particles was also calculated, but it leads in general to unstable thermodynamics.

  12. Nuclear physics detector technology applied to plant biology research

    SciTech Connect

    Weisenberger, Andrew G.; Kross, Brian J.; Lee, Seung Joo; McKisson, John E.; Xi, Wenze; Zorn, Carl J.; Howell, Calvin; Crowell, A.S.; Reid, C.D.; Smith, Mark

    2013-08-01

    The ability to detect the emissions of radioactive isotopes through radioactive decay (e.g. beta particles, x-rays and gamma-rays) has been used for over 80 years as a tracer method for studying natural phenomena. More recently a positron emitting radioisotope of carbon: {sup 11}C has been utilized as a {sup 11}CO{sub 2} tracer for plant ecophysiology research. Because of its ease of incorporation into the plant via photosynthesis, the {sup 11}CO{sub 2} radiotracer is a powerful tool for use in plant biology research. Positron emission tomography (PET) imaging has been used to study carbon transport in live plants using {sup 11}CO{sub 2}. Presently there are several groups developing and using new PET instrumentation for plant based studies. Thomas Jefferson National Accelerator Facility (Jefferson Lab) in collaboration with the Duke University Phytotron and the Triangle Universities Nuclear Laboratory (TUNL) is involved in PET detector development for plant imaging utilizing technologies developed for nuclear physics research. The latest developments of the use of a LYSO scintillator based PET detector system for {sup 11}CO{sub 2} tracer studies in plants will be briefly outlined.

  13. Cellular Solid-State NMR Investigation of a Membrane Protein Using Dynamic Nuclear Polarization

    PubMed Central

    Yamamoto, Kazutoshi; Caporini, Marc A.; Im, Sang-Choul; Waskell, Lucy; Ramamoorthy, Ayyalusamy

    2014-01-01

    While an increasing number of structural biology studies successfully demonstrate the power of high-resolution structures and dynamics of membrane proteins in fully understanding their function, there is considerable interest in developing NMR approaches to obtain such information in a cellular setting. As long as the proteins inside the living cell tumble rapidly in the NMR timescale, recently developed in-cell solution NMR approaches can be applied towards the determination of 3D structural information. However, there are numerous challenges that need to be overcome to study membrane proteins inside a cell. Research in our laboratory is focused on developing a combination of solid-state NMR and biological approaches to overcome these challenges with a specific emphasis on obtaining high-resolution structural insights into electron transfer biological processes mediated by membrane-bound proteins like mammalian cytochrome b5, cytochrome P450 and cytochrome P450 reductase. In this study, we demonstrate the feasibility of using the signal-enhancement rendered by dynamic nuclear polarization (DNP) magic angle spinning (MAS) NMR spectroscopy for in-cell studies on a membrane-anchored protein. Our experimental results obtained from 13C-labeled membrane-anchored cytochrome b5 in native Escherichia coli cells show a ~16-fold DNP signal enhancement (ε). Further, results obtained from a 2D 13C/13C chemical shift correlation MAS experiment demonstrates that it is highly possible to suppress the background signals from other cellular contents for high-resolution structural studies on membrane proteins. We believe that this study would pave new avenues for high-resolution 3D structural studies on a variety of membrane-associated proteins and their complexes in the cellular context to fully understand their functional roles in physiological processes. PMID:25017802

  14. Applying twisted boundary conditions for few-body nuclear systems

    NASA Astrophysics Data System (ADS)

    Körber, Christopher; Luu, Thomas

    2016-05-01

    We describe and implement twisted boundary conditions for the deuteron and triton systems within finite volumes using the nuclear lattice EFT formalism. We investigate the finite-volume dependence of these systems with different twist angles. We demonstrate how various finite-volume information can be used to improve calculations of binding energies in such a framework. Our results suggests that with appropriate twisting of boundaries, infinite-volume binding energies can be reliably extracted from calculations using modest volume sizes with cubic length L ≈8 -14 fm. Of particular importance is our derivation and numerical verification of three-body analogs of "i-periodic" twist angles that eliminate the leading-order finite-volume effects to the three-body binding energy.

  15. Achievement of high nuclear spin polarization using lanthanides as low-temperature NMR relaxation agents.

    PubMed

    Peat, David T; Horsewill, Anthony J; Köckenberger, Walter; Perez Linde, Angel J; Gadian, David G; Owers-Bradley, John R

    2013-05-28

    Many approaches are now available for achieving high levels of nuclear spin polarization. One of these methods is based on the notion that as the temperature is reduced, the equilibrium nuclear polarization will increase, according to the Boltzmann distribution. The main problem with this approach is the length of time it may take to approach thermal equilibrium at low temperatures, since nuclear relaxation times (characterized by the spin-lattice relaxation time T1) can become very long. Here, we show, by means of relaxation time measurements of frozen solutions, that selected lanthanide ions, in the form of their chelates with DTPA, can act as effective relaxation agents at low temperatures. Differential effects are seen with the different lanthanides that were tested, holmium and dysprosium showing highest relaxivity, while gadolinium is ineffective at temperatures of 20 K and below. These observations are consistent with the known electron-spin relaxation time characteristics of these lanthanides. The maximum relaxivity occurs at around 10 K for Ho-DTPA and 20 K for Dy-DTPA. Moreover, these two agents show only modest relaxivity at room temperature, and can thus be regarded as relaxation switches. We conclude that these agents can speed up solid state NMR experiments by reducing the T1 values of the relevant nuclei, and hence increasing the rate at which data can be acquired. They could also be of value in the context of a simple low-cost method of achieving several-hundred-fold improvements in polarization for experiments in which samples are pre-polarized at low temperatures, then rewarmed and dissolved immediately prior to analysis.

  16. Correlation measurements in nuclear {beta}-decay using traps and polarized low energy beams

    SciTech Connect

    Naviliat-Cuncic, Oscar

    2013-05-06

    Precision measurements in nuclear {beta}-decay provide sensitive means to test discrete symmetries in the weak interaction and to determine some of the fundamental constants in semi-leptonic decays, like the coupling of the lightest quarks to charged weak bosons. The main motivation of such measurements is to find deviations from Standard Model predictions as possible indications of new physics. In this contribution I will focus on two topics related to precision measurements in nuclear {beta}-decay: i) the determination of the V{sub ud} element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix from nuclear mirror transitions and ii) the search for exotic scalar or tensor contributions from {beta}{nu} angular correlations. The purpose is to underline the role being played by experimental techniques based on the confinement of radioactive species with atom and ion traps as well as the plans to use low energy polarized beams.

  17. Mapping the orientation of nuclear pore proteins in living cells with polarized fluorescence microscopy

    PubMed Central

    Kampmann, Martin; Atkinson, Claire E.; Mattheyses, Alexa L.; Simon, Sanford M.

    2011-01-01

    The nuclear pore complex (NPC) perforates the nuclear envelope to facilitate selective transport between nucleus and cytoplasm. The NPC is composed of multiple copies of ~30 different proteins, termed nucleoporins, whose arrangement within the NPC is a major unsolved puzzle in structural biology. Various alternative models for NPC architecture have been proposed but not tested experimentally in intact NPCs. We present a method using polarized fluorescence microscopy to investigate nucleoporin orientation in live yeast and mammalian cells. Our results support an arrangement of both yeast Nic96 and human Nup133–Nup107 with their long axes approximately parallel to the nuclear envelope plane. This method can complement X-ray crystallography and electron microscopy to generate a high-resolution map of the entire NPC, and could monitor nucleoporin rearrangements during nucleocytoplasmic transport and NPC assembly. This strategy can also be adapted for other macromolecular machines. PMID:21499242

  18. Low-Temperature Dynamic Nuclear Polarization at 9.4 Tesla With a 30 Milliwatt Microwave Source

    PubMed Central

    Thurber, Kent R.; Yau, Wai-Ming; Tycko, Robert

    2010-01-01

    Dynamic nuclear polarization (DNP) can provide large signal enhancements in nuclear magnetic resonance (NMR) by transfer of polarization from electron spins to nuclear spins. We discuss several aspects of DNP experiments at 9.4 Tesla (400 MHz resonant frequency for 1H, 264 GHz for electron spins in organic radicals) in the 7–80 K temperature range, using a 30 mW, frequency-tunable microwave source and a quasi-optical microwave bridge for polarization control and low-loss microwave transmission. In experiments on frozen glycerol/water doped with nitroxide radicals, DNP signal enhancements up to a factor of 80 are observed (relative to 1H NMR signals with thermal equilibrium spin polarization). The largest sensitivity enhancements are observed with a new triradical dopant, DOTOPA-TEMPO. Field modulation with a 10 G root-mean-squared amplitude during DNP increases the nuclear spin polarizations by up to 135%. Dependencies of 1H NMR signal amplitudes, nuclear spin relaxation times, and DNP build-up times on the dopant and its concentration, temperature, microwave power, and modulation frequency are reported and discussed. The benefits of low-temperature DNP can be dramatic: the 1H spin polarization is increased approximately 1000-fold at 7 K with DNP, relative to thermal polarization at 80 K. PMID:20392658

  19. Applying activity-based costing to the nuclear medicine unit.

    PubMed

    Suthummanon, Sakesun; Omachonu, Vincent K; Akcin, Mehmet

    2005-08-01

    Previous studies have shown the feasibility of using activity-based costing (ABC) in hospital environments. However, many of these studies discuss the general applications of ABC in health-care organizations. This research explores the potential application of ABC to the nuclear medicine unit (NMU) at a teaching hospital. The finding indicates that the current cost averages 236.11 US dollars for all procedures, which is quite different from the costs computed by using ABC. The difference is most significant with positron emission tomography scan, 463 US dollars (an increase of 96%), as well as bone scan and thyroid scan, 114 US dollars (a decrease of 52%). The result of ABC analysis demonstrates that the operational time (machine time and direct labour time) and the cost of drugs have the most influence on cost per procedure. Clearly, to reduce the cost per procedure for the NMU, the reduction in operational time and cost of drugs should be analysed. The result also indicates that ABC can be used to improve resource allocation and management. It can be an important aid in making management decisions, particularly for improving pricing practices by making costing more accurate. It also facilitates the identification of underutilized resources and related costs, leading to cost reduction. The ABC system will also help hospitals control costs, improve the quality and efficiency of the care they provide, and manage their resources better. PMID:16102243

  20. Applying activity-based costing to the nuclear medicine unit.

    PubMed

    Suthummanon, Sakesun; Omachonu, Vincent K; Akcin, Mehmet

    2005-08-01

    Previous studies have shown the feasibility of using activity-based costing (ABC) in hospital environments. However, many of these studies discuss the general applications of ABC in health-care organizations. This research explores the potential application of ABC to the nuclear medicine unit (NMU) at a teaching hospital. The finding indicates that the current cost averages 236.11 US dollars for all procedures, which is quite different from the costs computed by using ABC. The difference is most significant with positron emission tomography scan, 463 US dollars (an increase of 96%), as well as bone scan and thyroid scan, 114 US dollars (a decrease of 52%). The result of ABC analysis demonstrates that the operational time (machine time and direct labour time) and the cost of drugs have the most influence on cost per procedure. Clearly, to reduce the cost per procedure for the NMU, the reduction in operational time and cost of drugs should be analysed. The result also indicates that ABC can be used to improve resource allocation and management. It can be an important aid in making management decisions, particularly for improving pricing practices by making costing more accurate. It also facilitates the identification of underutilized resources and related costs, leading to cost reduction. The ABC system will also help hospitals control costs, improve the quality and efficiency of the care they provide, and manage their resources better.

  1. New filter for iodine applied in nuclear medicine services.

    PubMed

    Ramos, V S; Crispim, V R; Brandão, L E B

    2013-12-01

    In Nuclear Medicine, radioiodine, in various chemical forms, is a key tracer used in diagnostic practices and/or therapy. Medical professionals may incorporate radioactive iodine during the preparation of the dose to be administered to the patient. In radioactive iodine therapy doses ranging from 3.7 to 7.4 GBq per patient are employed. Thus, aiming at reducing the risk of occupational contamination, we developed a low cost filter to be installed at the exit of the exhaust system (where doses of radioiodine are handled within fume hoods, and new filters will be installed at their exit), using domestic technology. The effectiveness of radioactive iodine retention by silver impregnated silica [10%] crystals and natural activated carbon was verified using radiotracer techniques. The results showed that natural activated carbon and silver impregnated silica are effective for I2 capture with large or small amounts of substrate but the use of activated carbon is restricted due to its low flash point (423 K). Besides, when poisoned by organic solvents, this flash point may become lower, causing explosions if absorbing large amounts of nitrates. To hold the CH3I gas, it was necessary to use natural activated carbon since it was not absorbed by SiO2+Ag crystals. We concluded that, for an exhaust flow range of (145 ± 2)m(3)/h, a double stage filter using SiO2+Ag in the first stage and natural activated carbon in the second stage is sufficient to meet radiological safety requirements. PMID:23974306

  2. 250 GHz CW Gyrotron Oscillator for Dynamic Nuclear Polarization in Biological Solid State NMR

    PubMed Central

    Bajaj, Vikram S.; Hornstein, Melissa K.; Kreischer, Kenneth E.; Sirigiri, Jagadishwar R.; Woskov, Paul P.; Mak-Jurkauskas, Melody L.; Herzfeld, Judith; Temkin, Richard J.; Griffin, Robert G.

    2009-01-01

    In this paper, we describe a 250 GHz gyrotron oscillator, a critical component of an integrated system for magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments at 9T, corresponding to 380 MHz 1H frequency. The 250 GHz gyrotron is the first gyro-device designed with the goal of seamless integration with an NMR spectrometer for routine DNP-enhanced NMR spectroscopy and has operated under computer control for periods of up to 21 days with a 100% duty cycle. Following a brief historical review of the field, we present studies of the membrane protein bacteriorhodopsin (bR) using DNP-enhanced multidimensional NMR. These results include assignment of active site resonances in [U-13C,15N]-bR and demonstrate the utility of DNP for studies of membrane proteins. Next, we review the theory of gyro-devices from quantum mechanical and classical viewpoints and discuss the unique considerations that apply to gyrotron oscillators designed for DNP experiments. We then characterize the operation of the 250 GHz gyrotron in detail, including its long-term stability and controllability. We have measured the spectral purity of the gyrotron emission using both homodyne and heterodyne techniques. Radiation intensity patterns from the corrugated waveguide that delivers power to the NMR probe were measured using two new techniques to confirm pure mode content: a thermometric approach based on the temperature-dependent color of liquid crystalline media applied to a substrate and imaging with a pyroelectric camera. We next present a detailed study of the mode excitation characteristics of the gyrotron. Exploration of the operating characteristics of several fundamental modes reveals broadband continuous frequency tuning of up to 1.8 GHz as a function of the magnetic field alone, a feature that may be exploited in future tunable gyrotron designs. Oscillation of the 250 GHz gyrotron at the second harmonic of cyclotron resonance begins at extremely low beam currents (as low

  3. Applications of dynamic nuclear polarization to the study of reactions and reagents in organic and biomolecular chemistry.

    PubMed

    Hilty, Christian; Bowen, Sean

    2010-08-01

    Nuclear Magnetic Resonance (NMR) is an important spectroscopic tool for the identification and structural characterization of molecules in chemistry and biochemistry. The most significant limitation of NMR compared to other spectroscopies is its relatively low sensitivity, which thus often requires long measurement times or large amounts of sample. A way of increasing sensitivity of single scan NMR spectra by several orders of magnitude is through hyperpolarization of nuclear spins. Dynamic nuclear polarization allows hyperpolarization of most spins in small molecules encountered in chemistry and biochemistry. NMR spectra of small amounts of samples from natural source, or from chemical synthesis can readily be acquired. Perhaps more interestingly, the availability of the entire hyperpolarized NMR signal in one single scan allows the measurement of transient processes in real time, if applied together with a stopped-flow technique. Through observation of chemical shift, different reactant and product species can be distinguished, and kinetics and mechanisms, for example in enzyme catalyzed reactions, can be elucidated. Real-time hyperpolarization-enhanced NMR is uniquely amenable to correlating atomic positions not only through space, but also over time between reactant and product species. Such correlations carry mechanistic information about a reaction, and can prove reaction pathways. Applications of this technique are emerging in different areas of chemistry concerned with rapid reactions, including not only enzymatic processes, but also chemical catalysis and protein folding.

  4. Fourier factorization with complex polarization bases in the plane-wave expansion method applied to two-dimensional photonic crystals.

    PubMed

    Antos, Roman; Veis, Martin

    2010-12-20

    We demonstrate an enhancement of the plane wave expansion method treating two-dimensional photonic crystals by applying Fourier factorization with generally elliptic polarization bases. By studying three examples of periodically arranged cylindrical elements, we compare our approach to the classical Ho method in which the permittivity function is simply expanded without changing coordinates, and to the normal vector method using a normal-tangential polarization transform. The compared calculations clearly show that our approach yields the best convergence properties owing to the complete continuity of our distribution of polarization bases. The presented methodology enables us to study more general systems such as periodic elements with an arbitrary cross-section or devices such as photonic crystal waveguides. PMID:21197026

  5. Fourier factorization with complex polarization bases in the plane-wave expansion method applied to two-dimensional photonic crystals.

    PubMed

    Antos, Roman; Veis, Martin

    2010-12-20

    We demonstrate an enhancement of the plane wave expansion method treating two-dimensional photonic crystals by applying Fourier factorization with generally elliptic polarization bases. By studying three examples of periodically arranged cylindrical elements, we compare our approach to the classical Ho method in which the permittivity function is simply expanded without changing coordinates, and to the normal vector method using a normal-tangential polarization transform. The compared calculations clearly show that our approach yields the best convergence properties owing to the complete continuity of our distribution of polarization bases. The presented methodology enables us to study more general systems such as periodic elements with an arbitrary cross-section or devices such as photonic crystal waveguides.

  6. Check-All-That-Apply (CATA), Sorting, and Polarized Sensory Positioning (PSP) with Astringent Stimuli

    PubMed Central

    Fleming, Erin E.; Ziegler, Gregory R.; Hayes, John E.

    2015-01-01

    Multiple rapid sensory profiling techniques have been developed as more efficient alternatives to traditional sensory descriptive analysis. Here, we compare the results of three rapid sensory profiling techniques – check-all-that-apply (CATA), sorting, and polarized sensory positioning (PSP) – using a diverse range of astringent stimuli. These rapid methods differ in their theoretical basis, implementation, and data analyses, and the relative advantages and limitations are largely unexplored. Additionally, we were interested in using these methods to compare varied astringent stimuli, as these compounds are difficult to characterize using traditional descriptive analysis due to high fatigue and potential carry-over. In the CATA experiment, subjects (n=41) were asked to rate the overall intensity of each stimulus as well as to endorse any relevant terms (from a list of 13) which characterized the sample. In the sorting experiment, subjects (n=30) assigned intensity-matched stimuli into groups 1-on-1 with the experimenter. In the PSP experiment, (n=41) subjects first sampled and took notes on three blind references (‘poles’) before rating each stimulus for its similarity to each of the 3 poles. Two-dimensional perceptual maps from correspondence analysis (CATA), multidimensional scaling (sorting), and multiple factor analysis (PSP) were remarkably similar, with normalized RV coefficients indicating significantly similar plots, regardless of method. Agglomerative hierarchical clustering of all data sets using Ward’s minimum variance as the linkage criteria showed the clusters of astringent stimuli were approximately based on the respective class of astringent agent. Based on the descriptive CATA data, it appears these differences may be due to the presence of side tastes such as bitterness and sourness, rather than astringent sub-qualities per se. Although all three methods are considered ‘rapid,’ our prior experience with sorting suggests it is best

  7. Dynamic nuclear polarization enhancement of protons and vanadium-51 in the presence of pH-dependent vanadyl radicals.

    PubMed

    Perez Linde, Angel J; Carnevale, Diego; Miéville, Pascal; Sienkiewicz, Andrzej; Bodenhausen, Geoffrey

    2015-02-01

    We report applications of dynamic nuclear polarization to enhance proton and vanadium-51 polarization of vanadyl sulfate samples doped with TOTAPOL under magic angle spinning conditions. The electron paramagnetic resonance response stemming from the paramagnetic (51)V species was monitored as a function of pH, which can be adjusted to improve the enhancement of the proton polarization. By means of cross-polarization from the proton bath, (51)V spins could be hyperpolarized. Enhancement factors, build-up times, and longitudinal relaxation times T1((1)H) and T1((51)V) were investigated as a function of pH.

  8. Optimization of 1H spin density for dynamic nuclear polarization using photo-excited triplet electron spins.

    PubMed

    Kagawa, Akinori; Murokawa, Yu; Takeda, Kazuyuki; Kitagawa, Masahiro

    2009-03-01

    In dynamic nuclear polarization (DNP) using photo-excited triplet electron spins, known as Microwave-Induced Optical Nuclear Polarization (MIONP), the attainable (1)H polarization is determined by the ratio of the buildup rate and the spin-lattice relaxation rate, in turn depend on the (1)H spin density. It is shown that the final (1)H polarization can be enhanced by diluting the (1)H spins with partial deuteration. The DNP experiments are demonstrated in 0.05 mol% pentacene-doped p-terphenyl for various (1)H abundances. It is also shown that the (1)H spin diffusion coefficient can be determined by examining the initial buildup rate of (1)H polarization for various repetition rates of the DNP sequence.

  9. Instrumentation for solid-state dynamic nuclear polarization with magic angle spinning NMR.

    PubMed

    Rosay, Melanie; Blank, Monica; Engelke, Frank

    2016-03-01

    Advances in dynamic nuclear polarization (DNP) instrumentation and methodology have been key factors in the recent growth of solid-state DNP NMR applications. We review the current state of the art of solid-state DNP NMR instrumentation primarily based on available commercial platforms. We start with a general system overview, including options for microwave sources and DNP NMR probes, and then focus on specific developments for DNP at 100K with magic angle spinning (MAS). Gyrotron microwave sources, passive components to transmit microwaves, the DNP MAS probe, a cooling device for low-temperature MAS, and sample preparation procedures including radicals for DNP are considered. PMID:26920834

  10. THz-waves channeling in a monolithic saddle-coil for Dynamic Nuclear Polarization enhanced NMR.

    PubMed

    Macor, A; de Rijk, E; Annino, G; Alberti, S; Ansermet, J-Ph

    2011-10-01

    A saddle coil manufactured by electric discharge machining (EDM) from a solid piece of copper has recently been realized at EPFL for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance experiments (DNP-NMR) at 9.4 T. The corresponding electromagnetic behavior of radio-frequency (400 MHz) and THz (263 GHz) waves were studied by numerical simulation in various measurement configurations. Moreover, we present an experimental method by which the results of the THz-wave numerical modeling are validated. On the basis of the good agreement between numerical and experimental results, we conducted by numerical simulation a systematic analysis on the influence of the coil geometry and of the sample properties on the THz-wave field, which is crucial in view of the optimization of DNP-NMR in solids.

  11. Dynamic nuclear polarization methods in solids and solutions to explore membrane proteins and membrane systems.

    PubMed

    Cheng, Chi-Yuan; Han, Songi

    2013-01-01

    Membrane proteins regulate vital cellular processes, including signaling, ion transport, and vesicular trafficking. Obtaining experimental access to their structures, conformational fluctuations, orientations, locations, and hydration in membrane environments, as well as the lipid membrane properties, is critical to understanding their functions. Dynamic nuclear polarization (DNP) of frozen solids can dramatically boost the sensitivity of current solid-state nuclear magnetic resonance tools to enhance access to membrane protein structures in native membrane environments. Overhauser DNP in the solution state can map out the local and site-specific hydration dynamics landscape of membrane proteins and lipid membranes, critically complementing the structural and dynamics information obtained by electron paramagnetic resonance spectroscopy. Here, we provide an overview of how DNP methods in solids and solutions can significantly increase our understanding of membrane protein structures, dynamics, functions, and hydration in complex biological membrane environments. PMID:23331309

  12. The magnetic field dependence of cross-effect dynamic nuclear polarization under magic angle spinning

    SciTech Connect

    Mance, Deni; Baldus, Marc; Gast, Peter; Huber, Martina; Ivanov, Konstantin L.

    2015-06-21

    We develop a theoretical description of Dynamic Nuclear Polarization (DNP) in solids under Magic Angle Spinning (MAS) to describe the magnetic field dependence of the DNP effect. The treatment is based on an efficient scheme for numerical solution of the Liouville-von Neumann equation, which explicitly takes into account the variation of magnetic interactions during the sample spinning. The dependence of the cross-effect MAS-DNP on various parameters, such as the hyperfine interaction, electron-electron dipolar interaction, microwave field strength, and electron spin relaxation rates, is analyzed. Electron spin relaxation rates are determined by electron paramagnetic resonance measurements, and calculations are compared to experimental data. Our results suggest that the observed nuclear magnetic resonance signal enhancements provided by MAS-DNP can be explained by discriminating between “bulk” and “core” nuclei and by taking into account the slow DNP build-up rate for the bulk nuclei.

  13. Dynamic nuclear polarization in solid samples by electrical-discharge-induced radicals.

    PubMed

    Katz, Itai; Blank, Aharon

    2015-12-01

    Dynamic nuclear polarization (DNP) is a method for enhancing nuclear magnetic resonance (NMR) signals that has many potential applications in chemistry and medicine. Traditionally, DNP signal enhancement is achieved through the use of exogenous radicals mixed in a solution with the molecules of interest. Here we show that proton DNP signal enhancements can be obtained for solid samples without the use of solvent and exogenous radicals. Radicals are generated primarily on the surface of a solid sample using electrical discharges. These radicals are found suitable for DNP. They are stable under moderate vacuum conditions, yet readily annihilate upon compound dissolution or air exposure. This feature makes them attractive for use in medical applications, where the current variety of radicals used for DNP faces regulatory problems. In addition, this solvent-free method may be found useful for analytical NMR of solid samples which cannot tolerate solvents, such as certain pharmaceutical products.

  14. Dynamic Nuclear Polarization Methods in Solids and Solutions to Explore Membrane Proteins and Membrane Systems

    NASA Astrophysics Data System (ADS)

    Cheng, Chi-Yuan; Han, Songi

    2013-04-01

    Membrane proteins regulate vital cellular processes, including signaling, ion transport, and vesicular trafficking. Obtaining experimental access to their structures, conformational fluctuations, orientations, locations, and hydration in membrane environments, as well as the lipid membrane properties, is critical to understanding their functions. Dynamic nuclear polarization (DNP) of frozen solids can dramatically boost the sensitivity of current solid-state nuclear magnetic resonance tools to enhance access to membrane protein structures in native membrane environments. Overhauser DNP in the solution state can map out the local and site-specific hydration dynamics landscape of membrane proteins and lipid membranes, critically complementing the structural and dynamics information obtained by electron paramagnetic resonance spectroscopy. Here, we provide an overview of how DNP methods in solids and solutions can significantly increase our understanding of membrane protein structures, dynamics, functions, and hydration in complex biological membrane environments.

  15. Dynamic nuclear polarization in solid samples by electrical-discharge-induced radicals

    NASA Astrophysics Data System (ADS)

    Katz, Itai; Blank, Aharon

    2015-12-01

    Dynamic nuclear polarization (DNP) is a method for enhancing nuclear magnetic resonance (NMR) signals that has many potential applications in chemistry and medicine. Traditionally, DNP signal enhancement is achieved through the use of exogenous radicals mixed in a solution with the molecules of interest. Here we show that proton DNP signal enhancements can be obtained for solid samples without the use of solvent and exogenous radicals. Radicals are generated primarily on the surface of a solid sample using electrical discharges. These radicals are found suitable for DNP. They are stable under moderate vacuum conditions, yet readily annihilate upon compound dissolution or air exposure. This feature makes them attractive for use in medical applications, where the current variety of radicals used for DNP faces regulatory problems. In addition, this solvent-free method may be found useful for analytical NMR of solid samples which cannot tolerate solvents, such as certain pharmaceutical products.

  16. Applying laser speckle images to skin science: skin lesion differentiation by polarization

    NASA Astrophysics Data System (ADS)

    Lee, Tim K.; Tchvialeva, Lioudmila; Dhadwal, Gurbir; Sotoodian, Bahman; Kalai, Sunil; Zeng, Haishan; Lui, Harvey; McLean, David I.

    2012-01-01

    Skin cancer is a worldwide health problem. It is the most common cancer in the countries with a large white population; furthermore, the incidence of malignant melanoma, the most dangerous form of skin cancer, has been increasing steadily over the last three decades. There is an urgent need to develop in-vivo, noninvasive diagnostic tools for the disease. This paper attempts to response to the challenge by introducing a simple and fast method based on polarization and laser speckle. The degree of maintaining polarization estimates the fraction of linearly maintaining polarization in the backscattered speckle field. Clinical experiments of 214 skin lesions including malignant melanomas, squamous cell carcinomas, basal cell carcinomas, nevi, and seborrheic keratoses demonstrated that such a parameter can potentially diagnose different skin lesion types. ROC analyses showed that malignant melanoma and seborrheic keratosis could be differentiated by both the blue and red lasers with the area under the curve (AUC) = 0.8 and 0.7, respectively. Also malignant melanoma and squamous cell carcinoma could be separated by the blue laser (AUC = 0.9), while nevus and seborrheic keratosis could be identified using the red laser (AUC = 0.7). These experiments demonstrated that polarization could be a potential in-vivo diagnostic indicator for skin diseases.

  17. Applying laser speckle images to skin science: skin lesion differentiation by polarization

    NASA Astrophysics Data System (ADS)

    Lee, Tim K.; Tchvialeva, Lioudmila; Dhadwal, Gurbir; Sotoodian, Bahman; Kalai, Sunil; Zeng, Haishan; Lui, Harvey; McLean, David I.

    2011-09-01

    Skin cancer is a worldwide health problem. It is the most common cancer in the countries with a large white population; furthermore, the incidence of malignant melanoma, the most dangerous form of skin cancer, has been increasing steadily over the last three decades. There is an urgent need to develop in-vivo, noninvasive diagnostic tools for the disease. This paper attempts to response to the challenge by introducing a simple and fast method based on polarization and laser speckle. The degree of maintaining polarization estimates the fraction of linearly maintaining polarization in the backscattered speckle field. Clinical experiments of 214 skin lesions including malignant melanomas, squamous cell carcinomas, basal cell carcinomas, nevi, and seborrheic keratoses demonstrated that such a parameter can potentially diagnose different skin lesion types. ROC analyses showed that malignant melanoma and seborrheic keratosis could be differentiated by both the blue and red lasers with the area under the curve (AUC) = 0.8 and 0.7, respectively. Also malignant melanoma and squamous cell carcinoma could be separated by the blue laser (AUC = 0.9), while nevus and seborrheic keratosis could be identified using the red laser (AUC = 0.7). These experiments demonstrated that polarization could be a potential in-vivo diagnostic indicator for skin diseases.

  18. Introducing Students to Plant Geography: Polar Ordination Applied to Hanging Gardens.

    ERIC Educational Resources Information Center

    Malanson, George P.; And Others

    1993-01-01

    Reports on a research study in which college students used a statistical ordination method to reveal relationships among plant community structures and physical, disturbance, and spatial variables. Concludes that polar ordination helps students understand the methodology of plant geography and encourages further student research. (CFR)

  19. Different sets of ER-resident J-proteins regulate distinct polar nuclear-membrane fusion events in Arabidopsis thaliana.

    PubMed

    Maruyama, Daisuke; Yamamoto, Masaya; Endo, Toshiya; Nishikawa, Shuh-ichi

    2014-11-01

    Angiosperm female gametophytes contain a central cell with two polar nuclei. In many species, including Arabidopsis thaliana, the polar nuclei fuse during female gametogenesis. We previously showed that BiP, an Hsp70 in the endoplasmic reticulum (ER), was essential for membrane fusion during female gametogenesis. Hsp70 function requires partner proteins for full activity. J-domain containing proteins (J-proteins) are the major Hsp70 functional partners. A. thaliana ER contains three soluble J-proteins, AtERdj3A, AtERdj3B, and AtP58(IPK). Here, we analyzed mutants of these proteins and determined that double-mutant ovules lacking AtP58(IPK) and AtERdj3A or AtERdj3B were defective in polar nuclear fusion. Electron microscopy analysis identified that polar nuclei were in close contact, but no membrane fusion occurred in mutant ovules lacking AtP58(IPK) and AtERdj3A. The polar nuclear outer membrane appeared to be connected via the ER remaining at the inner unfused membrane in mutant ovules lacking AtP58(IPK) and AtERdj3B. These results indicate that ER-resident J-proteins, AtP58(IPK)/AtERdj3A and AtP58(IPK)/AtERdj3B, function at distinct steps of polar nuclear-membrane fusion. Similar to the bip1 bip2 double mutant female gametophytes, the aterdj3a atp58(ipk) double mutant female gametophytes defective in fusion of the outer polar nuclear membrane displayed aberrant endosperm proliferation after fertilization with wild-type pollen. However, endosperm proliferated normally after fertilization of the aterdj3b atp58(ipk) double mutant female gametophytes defective in fusion of the inner membrane. Our results indicate that the polar nuclear fusion defect itself does not cause an endosperm proliferation defect.

  20. Overhauser Geomagnetic Sensor Based on the Dynamic Nuclear Polarization Effect for Magnetic Prospecting.

    PubMed

    Ge, Jian; Dong, Haobin; Liu, Huan; Yuan, Zhiwen; Dong, He; Zhao, Zhizhuo; Liu, Yonghua; Zhu, Jun; Zhang, Haiyang

    2016-01-01

    Based on the dynamic nuclear polarization (DNP) effect, an alternative design of an Overhauser geomagnetic sensor is presented that enhances the proton polarization and increases the amplitude of the free induction decay (FID) signal. The short-pulse method is adopted to rotate the enhanced proton magnetization into the plane of precession to create an FID signal. To reduce the negative effect of the powerful electromagnetic interference, the design of the anti-interference of the pick-up coil is studied. Furthermore, the radio frequency polarization method based on the capacitive-loaded coaxial cavity is proposed to improve the quality factor of the resonant circuit. In addition, a special test instrument is designed that enables the simultaneous testing of the classical proton precession and the Overhauser sensor. Overall, comparison experiments with and without the free radical of the Overhauser sensors show that the DNP effect does effectively improve the amplitude and quality of the FID signal, and the magnetic sensitivity, resolution and range reach to 10 pT/Hz 1 / 2 @1 Hz, 0.0023 nT and 20-100 μ T, respectively. PMID:27258283

  1. Overhauser Geomagnetic Sensor Based on the Dynamic Nuclear Polarization Effect for Magnetic Prospecting

    PubMed Central

    Ge, Jian; Dong, Haobin; Liu, Huan; Yuan, Zhiwen; Dong, He; Zhao, Zhizhuo; Liu, Yonghua; Zhu, Jun; Zhang, Haiyang

    2016-01-01

    Based on the dynamic nuclear polarization (DNP) effect, an alternative design of an Overhauser geomagnetic sensor is presented that enhances the proton polarization and increases the amplitude of the free induction decay (FID) signal. The short-pulse method is adopted to rotate the enhanced proton magnetization into the plane of precession to create an FID signal. To reduce the negative effect of the powerful electromagnetic interference, the design of the anti-interference of the pick-up coil is studied. Furthermore, the radio frequency polarization method based on the capacitive-loaded coaxial cavity is proposed to improve the quality factor of the resonant circuit. In addition, a special test instrument is designed that enables the simultaneous testing of the classical proton precession and the Overhauser sensor. Overall, comparison experiments with and without the free radical of the Overhauser sensors show that the DNP effect does effectively improve the amplitude and quality of the FID signal, and the magnetic sensitivity, resolution and range reach to 10 pT/Hz1/2@1 Hz, 0.0023 nT and 20–100 μT, respectively. PMID:27258283

  2. Dynamic nuclear polarization at 9 T using a novel 250 GHz gyrotron microwave source

    NASA Astrophysics Data System (ADS)

    Bajaj, V. S.; Farrar, C. T.; Hornstein, M. K.; Mastovsky, I.; Vieregg, J.; Bryant, J.; Eléna, B.; Kreischer, K. E.; Temkin, R. J.; Griffin, R. G.

    2003-02-01

    In this communication, we report enhancements of nuclear spin polarization by dynamic nuclear polarization (DNP) in static and spinning solids at a magnetic field strength of 9 T (250 GHz for g=2 electrons, 380 MHz for 1H). In these experiments, 1H enhancements of up to 170±50 have been observed in 1- 13C-glycine dispersed in a 60:40 glycerol/water matrix at temperatures of 20 K; in addition, we have observed significant enhancements in 15N spectra of unoriented pf1-bacteriophage. Finally, enhancements of ˜17 have been obtained in two-dimensional 13C- 13C chemical shift correlation spectra of the amino acid U- 13C, 15N-proline during magic angle spinning (MAS), demonstrating the stability of the DNP experiment for sustained acquisition and for quantitative experiments incorporating dipolar recoupling. In all cases, we have exploited the thermal mixing DNP mechanism with the nitroxide radical 4-amino-TEMPO as the paramagnetic dopant. These are the highest frequency DNP experiments performed to date and indicate that significant signal enhancements can be realized using the thermal mixing mechanism even at elevated magnetic fields. In large measure, this is due to the high microwave power output of the 250 GHz gyrotron oscillator used in these experiments.

  3. Dynamic nuclear polarization at 9 T using a novel 250 GHz gyrotron microwave source

    NASA Astrophysics Data System (ADS)

    Bajaj, V. S.; Farrar, C. T.; Hornstein, M. K.; Mastovsky, I.; Vieregg, J.; Bryant, J.; Eléna, B.; Kreischer, K. E.; Temkin, R. J.; Griffin, R. G.

    2011-12-01

    In this communication, we report enhancements of nuclear spin polarization by dynamic nuclear polarization (DNP) in static and spinning solids at a magnetic field strength of 9 T (250 GHz for g = 2 electrons, 380 MHz for 1H). In these experiments, 1H enhancements of up to 170 ± 50 have been observed in 1- 13C-glycine dispersed in a 60:40 glycerol/water matrix at temperatures of 20 K; in addition, we have observed significant enhancements in 15N spectra of unoriented pf1-bacteriophage. Finally, enhancements of ˜17 have been obtained in two-dimensional 13C- 13C chemical shift correlation spectra of the amino acid U- 13C, 15N-proline during magic angle spinning (MAS), demonstrating the stability of the DNP experiment for sustained acquisition and for quantitative experiments incorporating dipolar recoupling. In all cases, we have exploited the thermal mixing DNP mechanism with the nitroxide radical 4-amino-TEMPO as the paramagnetic dopant. These are the highest frequency DNP experiments performed to date and indicate that significant signal enhancements can be realized using the thermal mixing mechanism even at elevated magnetic fields. In large measure, this is due to the high microwave power output of the 250 GHz gyrotron oscillator used in these experiments.

  4. Dynamic nuclear polarization at 9T using a novel 250GHz gyrotron microwave source

    PubMed Central

    Bajaj, V.S.; Farrar, C.T.; Hornstein, M.K.; Mastovsky, I.; Vieregg, J.; Bryant, J.; Eléna, B.; Kreischer, K.E.; Temkin, R.J.; Griffin, R.G.

    2010-01-01

    In this communication, we report enhancements of nuclear spin polarization by dynamic nuclear polarization (DNP) in static and spinning solids at a magnetic field strength of 9T (250 GHz for g = 2 electrons, 380 MHz for 1H). In these experiments, 1H enhancements of up to 170 ± 50 have been observed in 1-13C-glycine dispersed in a 60:40 glycerol/water matrix at temperatures of 20 K; in addition, we have observed significant enhancements in 15N spectra of unoriented pf1-bacteriophage. Finally, enhancements of ~17 have been obtained in two-dimensional 13C–13C chemical shift correlation spectra of the amino acid U-13C, 15N-proline during magic angle spinning (MAS), demonstrating the stability of the DNP experiment for sustained acquisition and for quantitative experiments incorporating dipolar recoupling. In all cases, we have exploited the thermal mixing DNP mechanism with the nitroxide radical 4-amino-TEMPO as the paramagnetic dopant. These are the highest frequency DNP experiments performed to date and indicate that significant signal enhancements can be realized using the thermal mixing mechanism even at elevated magnetic fields. In large measure, this is due to the high microwave power output of the 250 GHz gyrotron oscillator used in these experiments. PMID:12615147

  5. Dynamic nuclear polarization at 9T using a novel 250GHz gyrotron microwave source.

    PubMed

    Bajaj, V S; Farrar, C T; Hornstein, M K; Mastovsky, I; Vieregg, J; Bryant, J; Eléna, B; Kreischer, K E; Temkin, R J; Griffin, R G

    2003-02-01

    In this communication, we report enhancements of nuclear spin polarization by dynamic nuclear polarization (DNP) in static and spinning solids at a magnetic field strength of 9T (250 GHz for g=2 electrons, 380 MHz for 1H). In these experiments, 1H enhancements of up to 170+/-50 have been observed in 1-13C-glycine dispersed in a 60:40 glycerol/water matrix at temperatures of 20K; in addition, we have observed significant enhancements in 15N spectra of unoriented pf1-bacteriophage. Finally, enhancements of approximately 17 have been obtained in two-dimensional 13C-13C chemical shift correlation spectra of the amino acid U-13C, 15N-proline during magic angle spinning (MAS), demonstrating the stability of the DNP experiment for sustained acquisition and for quantitative experiments incorporating dipolar recoupling. In all cases, we have exploited the thermal mixing DNP mechanism with the nitroxide radical 4-amino-TEMPO as the paramagnetic dopant. These are the highest frequency DNP experiments performed to date and indicate that significant signal enhancements can be realized using the thermal mixing mechanism even at elevated magnetic fields. In large measure, this is due to the high microwave power output of the 250 GHz gyrotron oscillator used in these experiments.

  6. Milli-tesla NMR and spectrophotometry of liquids hyperpolarized by dissolution dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Zhu, Yue; Chen, Chia-Hsiu; Wilson, Zechariah; Savukov, Igor; Hilty, Christian

    2016-09-01

    Hyperpolarization methods offer a unique means of improving low signal strength obtained in low-field NMR. Here, simultaneous measurements of NMR at a field of 0.7 mT and laser optical absorption from samples hyperpolarized by dissolution dynamic nuclear polarization (D-DNP) are reported. The NMR measurement field closely corresponds to a typical field encountered during sample injection in a D-DNP experiment. The optical spectroscopy allows determination of the concentration of the free radical required for DNP. Correlation of radical concentration to NMR measurement of spin polarization and spin-lattice relaxation time allows determination of relaxivity and can be used for optimization of the D-DNP process. Further, the observation of the nuclear Overhauser effect originating from hyperpolarized spins is demonstrated. Signals from 1H and 19F in a mixture of trifluoroethanol and water are detected in a single spectrum, while different atoms of the same type are distinguished by J-coupling patterns. The resulting signal changes of individual peaks are indicative of molecular contact, suggesting a new application area of hyperpolarized low-field NMR for the determination of intermolecular interactions.

  7. Experimental demonstration of stimulated polarization wave in a chain of nuclear spins

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Seung; Adams, Travis; Khitrin, Anatoly

    2007-03-01

    A one-dimensional Ising chain irradiated by weak resonant transverse field is the simplest model of quantum amplifier [Phys. Rev. A 71, 062338 (2005)]. The quantum state of the chain is stationary when all the qubits (spins) are in the same state. However, when the first qubit is flipped, it triggers a stimulated wave of flipped qubits, propagating through the chain. Such ``quantum domino" dynamics induces huge change in the total polarization, a macroscopic observable. Here we present the experimental demonstration of this quantum amplification process on a four-qubit system by using nuclear magnetic resonance technique. The physical system is a linear chain of four ^13C nuclear spins in a molecule of fully ^ 13C-labeled sodium butyrate dissolved in D2O. The pseudopure ground state (with all spins up) is prepared by multi-frequency partial saturation. The wave of flipped spins has been clearly observed when the first spin of the chain is flipped. We define a coefficient of amplification as the relative enhancement of the total polarization change. In our experimental system, the measured coefficient of amplification is about 3.

  8. Storage of quantum coherences as phase-labelled local polarization in solid-state nuclear magnetic resonance.

    PubMed

    Franzoni, María Belén; Acosta, Rodolfo H; Pastawski, Horacio M; Levstein, Patricia R

    2012-10-13

    Nuclear spins are promising candidates for quantum information processing because their good isolation from the environment precludes the rapid loss of quantum coherence. Many strategies have been developed to further extend their decoherence times. Some of them make use of decoupling techniques based on the Carr-Purcell and Carr-Purcell-Meiboom-Gill pulse sequences. In many cases, when applied to inhomogeneous samples, they yield a magnetization decay much slower than that of the Hahn echo. However, we have proved that these decays cannot be associated with longer decoherence times, as coherences remain frozen. They result from coherences recovered after their storage as local polarization and thus they can be used as memories. We show here how this freezing of the coherent state, which can subsequently be recovered after times longer than the natural decoherence time of the system, can be generated in a controlled way with the use of field gradients. A similar behaviour of homogeneous samples in inhomogeneous fields is demonstrated. It is emphasized that the effects of inhomogeneities in solid-state nuclear magnetic resonance, independently of their origin, should not be disregarded, as they play a crucial role in multipulse sequences.

  9. Prospects for Sub-Micron Solid State Nuclear Magnetic Resonance Imaging with Low-Temperature Dynamic Nuclear Polarization

    PubMed Central

    Thurber, Kent R.; Tycko, Robert

    2010-01-01

    Summary We evaluate the feasibility of 1H nuclear magnetic resonance (NMR) imaging with sub-micron voxel dimensions using a combination of low temperatures and dynamic nuclear polarization (DNP). Experiments are performed on nitroxide-doped glycerol/water at 9.4 T and temperatures below 40 K, using a 30 mW tunable microwave source for DNP. With DNP at 7 K, a 0.5 µl sample yields a 1H NMR signal-to-noise ratio of 770 in two scans with pulsed spin-lock detection and after 80 db signal attenuation. With reasonable extrapolations, we infer that 1H NMR signals from 1 µm3 voxel volumes should be readily detectable, and voxels as small as 0.03 µm3 may eventually be detectable. Through homonuclear decoupling with a frequency-switched Lee-Goldburg spin echo technique, we obtain 830 Hz 1H NMR linewidths at low temperatures, implying that pulsed field gradients equal to 0.4 G/d or less would be required during spatial encoding dimensions of an imaging sequence, where d is the resolution in each dimension. PMID:20458431

  10. Seismic risk assessment as applied to the Zion Nuclear Generating Station

    SciTech Connect

    Wells, J.

    1984-08-01

    To assist the US Nuclear Regulatory Commission (NRC) in its licensing and evaluation role, the NRC funded the Seismic Safety Margins Research Program (SSMRP) at Lawrence Livermore National Laboratory (LLNL) with the goal of developing tools and data bases to evaluate the risk of earthquake caused radioactive release from a commercial nuclear power plant. This paper describes the SSMRP risk assessment methodology and the results generated by applying this methodology to the Zion Nuclear Generating Station. In addition to describing the failure probabilities and risk values, the effects of assumptions about plant configuration, plant operation, and dependence will be given.

  11. Polarization of PI3K Activity Initiated by Ooplasmic Segregation Guides Nuclear Migration in the Mesendoderm.

    PubMed

    Takatori, Naohito; Oonuma, Kouhei; Nishida, Hiroki; Saiga, Hidetoshi

    2015-11-01

    Asymmetric localization of RNA is a widely observed mechanism of cell polarization. Using embryos of the ascidian, Halocynthia roretzi, we previously showed that mesoderm and endoderm fates are separated by localization of mRNA encoding a transcription factor, Not, to the future mesoderm-side cytoplasm of the mesendoderm cell through asymmetric positioning of the nucleus. Here, we investigated the mechanism that defines the direction of the nuclear migration. We show that localization of PtdIns(3,4,5)P3 to the future mesoderm region determines the direction of nuclear migration. Localization of PtdIns(3,4,5)P3 was dependent on the localization of PI3Kα to the future mesoderm region. PI3Kα was first localized at the 1-cell stage by the ooplasmic movement. Activity of localized PI3Kα at the 4-cell stage was required for the localization of PI3Kα up to the nuclear migration. Our results provide the scaffold for understanding the chain of causality leading to the separation of germ layer fates. PMID:26555053

  12. Observation of strongly forbidden solid effect dynamic nuclear polarization transitions via electron-electron double resonance detected NMR

    SciTech Connect

    Smith, Albert A.; Corzilius, Björn; Haze, Olesya; Swager, Timothy M.; Griffin, Robert G.

    2013-12-07

    We present electron paramagnetic resonance experiments for which solid effect dynamic nuclear polarization transitions were observed indirectly via polarization loss on the electron. This use of indirect observation allows characterization of the dynamic nuclear polarization (DNP) process close to the electron. Frequency profiles of the electron-detected solid effect obtained using trityl radical showed intense saturation of the electron at the usual solid effect condition, which involves a single electron and nucleus. However, higher order solid effect transitions involving two, three, or four nuclei were also observed with surprising intensity, although these transitions did not lead to bulk nuclear polarization—suggesting that higher order transitions are important primarily in the transfer of polarization to nuclei nearby the electron. Similar results were obtained for the SA-BDPA radical where strong electron-nuclear couplings produced splittings in the spectrum of the indirectly observed solid effect conditions. Observation of high order solid effect transitions supports recent studies of the solid effect, and suggests that a multi-spin solid effect mechanism may play a major role in polarization transfer via DNP.

  13. Effect of electron spin dynamics on solid-state dynamic nuclear polarization performance.

    PubMed

    Siaw, Ting Ann; Fehr, Matthias; Lund, Alicia; Latimer, Allegra; Walker, Shamon A; Edwards, Devin T; Han, Song-I

    2014-09-21

    For the broadest dissemination of solid-state dynamic nuclear polarization (ssDNP) enhanced NMR as a material characterization tool, the ability to employ generic mono-nitroxide radicals as spin probes is critical. A better understanding of the factors contributing to ssDNP efficiency is needed to rationally optimize the experimental condition for the practically accessible spin probes at hand. This study seeks to advance the mechanistic understanding of ssDNP by examining the effect of electron spin dynamics on ssDNP performance at liquid helium temperatures (4-40 K). The key observation is that bi-radicals and mono-radicals can generate comparable nuclear spin polarization at 4 K and 7 T, which is in contrast to the observation for ssDNP at liquid nitrogen temperatures (80-150 K) that finds bi-radicals to clearly outperform mono-radicals. To rationalize this observation, we analyze the change in the DNP-induced nuclear spin polarization (Pn) and the characteristic ssDNP signal buildup time as a function of electron spin relaxation rates that are modulated by the mono- and bi-radical spin concentration. Changes in Pn are consistent with a systematic variation in the product of the electron spin-lattice relaxation time and the electron spin flip-flop rate that constitutes an integral saturation factor of an inhomogeneously broadened EPR spectrum. We show that the comparable Pn achieved with both radical species can be reconciled with a comparable integral EPR saturation factor. Surprisingly, the largest Pn is observed at an intermediate spin concentration for both mono- and bi-radicals. At the highest radical concentration, the stronger inter-electron spin dipolar coupling favors ssDNP, while oversaturation diminishes Pn, as experimentally verified by the observation of a maximum Pn at an intermediate, not the maximum, microwave (μw) power. At the maximum μw power, oversaturation reduces the electron spin population differential that must be upheld between

  14. The use of dynamic nuclear polarization 13C-pyruvate MRS in cancer

    PubMed Central

    Gutte, Henrik; Hansen, Adam Espe; Johannesen, Helle Hjorth; Clemmensen, Andreas Ettrup; Ardenkjær-Larsen, Jan Henrik; Nielsen, Carsten Haagen; Kjær, Andreas

    2015-01-01

    In recent years there has been an immense development of new targeted anti-cancer drugs. For practicing precision medicine, a sensitive method imaging for non-invasive, assessment of early treatment response and for assisting in developing new drugs is warranted. Magnetic Resonance Spectroscopy (MRS) is a potent technique for non-invasive in vivo investigation of tissue chemistry and cellular metabolism. Hyperpolarization by Dynamic Nuclear Polarization (DNP) is capable of creating solutions of molecules with polarized nuclear spins in a range of biological molecules and has enabled the real-time investigation of in vivo metabolism. The development of this new method has been demonstrated to enhance the nuclear polarization more than 10,000-fold, thereby significantly increasing the sensitivity of the MRS with a spatial resolution to the millimeters and a temporal resolution at the subsecond range. Furthermore, the method enables measuring kinetics of conversion of substrates into cell metabolites and can be integrated with anatomical proton magnetic resonance imaging (MRI). Many nuclei and substrates have been hyperpolarized using the DNP method. Currently, the most widely used compound is 13C-pyruvate due to favoring technicalities. Intravenous injection of the hyperpolarized 13C-pyruvate results in appearance of 13C-lactate, 13C-alanine and 13C-bicarbonate resonance peaks depending on the tissue, disease and the metabolic state probed. In cancer, the lactate level is increased due to increased glycolysis. The use of DNP enhanced 13C-pyruvate has in preclinical studies shown to be a sensitive method for detecting cancer and for assessment of early treatment response in a variety of cancers. Recently, a first-in-man 31-patient study was conducted with the primary objective to assess the safety of hyperpolarized 13C-pyruvate in healthy subjects and prostate cancer patients. The study showed an elevated 13C-lactate/13C-pyruvate ratio in regions of biopsy

  15. Spin disorder in maghemite nanoparticles investigated using polarized neutrons and nuclear resonant scattering

    SciTech Connect

    Herlitschke, Marcus; Disch, Sabrina; Sergueev, I.; Schlage, Kai; Wetterskog, Erik; Bergstrom, Lennart; Hermann, Raphael P.

    2016-01-01

    The manuscript reports the investigation of spin disorder in maghemite nanoparticles of different shape by a combination of polarized small-angle neutron scattering (SANSPOL) and nuclear forward scattering (NFS) techniques. Both methods are sensitive to magnetization on the nanoscale. SANSPOL allows for investigation of the particle morphology and spatial magnetization distribution and NFS extends this nanoscale information to the atomic scale, namely the orientation of the hyperfine field experienced by the iron nuclei. The studied nanospheres and nanocubes with diameters of 7.4nm and 10.6 nm, respectively, exhibit a significant spin disorder. This effect leads to a reduction of the magnetization to 44% and 58% of the theoretical maghemite bulk value, observed consistently by both techniques.

  16. Surface Binding of TOTAPOL Assists Structural Investigations of Amyloid Fibrils by Dynamic Nuclear Polarization NMR Spectroscopy.

    PubMed

    Nagaraj, Madhu; Franks, Trent W; Saeidpour, Siavash; Schubeis, Tobias; Oschkinat, Hartmut; Ritter, Christiane; van Rossum, Barth-Jan

    2016-07-15

    Dynamic nuclear polarization (DNP) NMR can enhance sensitivity but often comes at the price of a substantial loss of resolution. Two major factors affect spectral quality: low-temperature heterogeneous line broadening and paramagnetic relaxation enhancement (PRE) effects. Investigations by NMR spectroscopy, isothermal titration calorimetry (ITC), and EPR revealed a new substantial affinity of TOTAPOL to amyloid surfaces, very similar to that shown by the fluorescent dye thioflavin-T (ThT). As a consequence, DNP spectra with remarkably good resolution and still reasonable enhancement could be obtained at very low TOTAPOL concentrations, typically 400 times lower than commonly employed. These spectra yielded several long-range constraints that were difficult to obtain without DNP. Our findings open up new strategies for structural studies with DNP NMR spectroscopy on amyloids that can bind the biradical with affinity similar to that shown towards ThT. PMID:27147408

  17. Low temperature probe for dynamic nuclear polarization and multiple-pulse solid-state NMR.

    PubMed

    Cho, HyungJoon; Baugh, Jonathan; Ryan, Colm A; Cory, David G; Ramanathan, Chandrasekhar

    2007-08-01

    Here, we describe the design and performance characteristics of a low temperature probe for dynamic nuclear polarization (DNP) experiments, which is compatible with demanding multiple-pulse experiments. The competing goals of a high-Q microwave cavity to achieve large DNP enhancements and a high efficiency NMR circuit for multiple-pulse control lead to inevitable engineering tradeoffs. We have designed two probes-one with a single-resonance RF circuit and a horn-mirror cavity configuration for the microwaves and a second with a double-resonance RF circuit and a double-horn cavity configuration. The advantage of the design is that the sample is in vacuum, the RF circuits are locally tuned, and the microwave resonator has a large internal volume that is compatible with the use of RF and gradient coils.

  18. Spin disorder in maghemite nanoparticles investigated using polarized neutrons and nuclear resonant scattering

    DOE PAGES

    Herlitschke, Marcus; Disch, Sabrina; Sergueev, I.; Schlage, Kai; Wetterskog, Erik; Bergstrom, Lennart; Hermann, Raphael P.

    2016-01-01

    The manuscript reports the investigation of spin disorder in maghemite nanoparticles of different shape by a combination of polarized small-angle neutron scattering (SANSPOL) and nuclear forward scattering (NFS) techniques. Both methods are sensitive to magnetization on the nanoscale. SANSPOL allows for investigation of the particle morphology and spatial magnetization distribution and NFS extends this nanoscale information to the atomic scale, namely the orientation of the hyperfine field experienced by the iron nuclei. The studied nanospheres and nanocubes with diameters of 7.4nm and 10.6 nm, respectively, exhibit a significant spin disorder. This effect leads to a reduction of the magnetization tomore » 44% and 58% of the theoretical maghemite bulk value, observed consistently by both techniques.« less

  19. Waveguide transition with vacuum window for multiband dynamic nuclear polarization systems

    NASA Astrophysics Data System (ADS)

    Rybalko, Oleksandr; Bowen, Sean; Zhurbenko, Vitaliy; Ardenkjær-Larsen, Jan Henrik

    2016-05-01

    A low loss waveguide transition section and oversized microwave vacuum window covering several frequency bands (94 GHz, 140 GHz, 188 GHz) is presented. The transition is compact and was optimized for multiband Dynamic Nuclear Polarization (DNP) systems in a full-wave simulator. The window is more broadband than commercially available windows, which are usually optimized for single band operation. It is demonstrated that high-density polyethylene with urethane adhesive can be used as a low loss microwave vacuum window in multiband DNP systems. The overall assembly performance and dimensions are found using full-wave simulations. The practical aspects of the window implementation in the waveguide are discussed. To verify the design and simulation results, the window is tested experimentally at the three frequencies of interest.

  20. Evaluation of nuclear facility decommissioning projects. Summary report: Three Mile Island Unit 2 polar crane recovery

    SciTech Connect

    Doerge, D.H.; Miller, R.L.

    1984-08-01

    This document summarizes information concerning restoration of the Three Mile Island-Unit 2 Polar Crane to a fully operational condition following the loss of coolant accident experienced on March 28, 1979. The data collected from activity reports, reactor containment entry records, and other sources were placed in a computerized information retrieval/manipulation system which permits extraction/manipulation of specific data which could be utilized in planning for recovery activities should a similar accident occur in a nuclear generating plant. The information is presented in both computer output form and a manually assembled summarization. This report contains only the manpower requirements and radiation exposures actually incurred during recovery operations within the reactor containment and does not include support activities or costs.

  1. Applying polarity rapid assessment method and ultrafiltration to characterize NDMA precursors in wastewater effluents.

    PubMed

    Chen, Chao; Leavey, Shannon; Krasner, Stuart W; Mel Suffet, I H

    2014-06-15

    Certain nitrosamines in water are disinfection byproducts that are probable human carcinogens. Nitrosamines have diverse and complex precursors that include effluent organic matter, some anthropogenic chemicals, and natural (likely non-humic) substances. An easy and selective tool was first developed to characterize nitrosamine precursors in treated wastewaters, including different process effluents. This tool takes advantages of the polarity rapid assessment method (PRAM) and ultrafiltration (UF) (molecular weight distribution) to locate the fractions with the strongest contributions to the nitrosamine precursor pool in the effluent organic matter. Strong cation exchange (SCX) and C18 solid-phase extraction cartridges were used for their high selectivity for nitrosamine precursors. The details of PRAM operation, such as cartridge clean-up, capacity, pH influence, and quality control were included in this paper, as well as the main parameters of UF operation. Preliminary testing of the PRAM/UF method with effluents from one wastewater treatment plant gave very informative results. SCX retained 45-90% of the N-nitrosodimethylamine (NDMA) formation potential (FP)-a measure of the precursors-in secondary and tertiary wastewater effluents. These results are consistent with NDMA precursors likely having a positively charged amine group. C18 adsorbed 30-45% of the NDMAFP, which indicates that a substantial portion of these precursors were non-polar. The small molecular weight (MW) (<1 kDa) and large MW (>10 kDa) fractions obtained from UF were the primary contributors to NDMAFP. The combination of PRAM and UF brings important information on the characteristics of nitrosamine precursors in water with easy operation.

  2. Solid-State NMR/Dynamic Nuclear Polarization of Polypeptides in Planar Supported Lipid Bilayers.

    PubMed

    Salnikov, Evgeniy S; Sarrouj, Hiba; Reiter, Christian; Aisenbrey, Christopher; Purea, Armin; Aussenac, Fabien; Ouari, Olivier; Tordo, Paul; Fedotenko, Illya; Engelke, Frank; Bechinger, Burkhard

    2015-11-19

    Dynamic nuclear polarization has been developed to overcome the limitations of the inherently low signal intensity of NMR spectroscopy. This technique promises to be particularly useful for solid-state NMR spectroscopy where the signals are broadened over a larger frequency range and most investigations rely on recording low gamma nuclei. To extend the range of possible investigations, a triple-resonance flat-coil solid-state NMR probe is presented with microwave irradiation capacities allowing the investigation of static samples at temperatures of 100 K, including supported lipid bilayers. The probe performance allows for two-dimensional separated local field experiments with high-power Lee-Goldberg decoupling and cross-polarization under simultaneous irradiation from a gyrotron microwave generator. Efficient cooling of the sample turned out to be essential for best enhancements and line shape and necessitated the development of a dedicated cooling chamber. Furthermore, a new membrane-anchored biradical is presented, and the geometry of supported membranes was optimized not only for good membrane alignment, handling, stability, and filling factor of the coil but also for heat and microwave dissipation. Enhancement factors of 17-fold were obtained, and a two-dimensional PISEMA spectrum of a transmembrane helical peptide was obtained in less than 2 h. PMID:26487390

  3. Control of transmission of right circularly polarized laser light in overdense plasma by applied magnetic field pulses.

    PubMed

    Ma, Guangjin; Yu, Wei; Yu, M Y; Luan, Shixia; Wu, Dong

    2016-05-01

    The effect of a transient magnetic field on right-hand circularly polarized (RHCP) laser light propagation in overcritical-density plasma is investigated. When the electron gyrofrequency is larger than the wave frequency, RHCP light can propagate along the external magnetic field in an overcritical density plasma without resonance or cutoff. However, when the magnetic field falls to below the cyclotron resonance point, the propagating laser pulse will be truncated and the local plasma electrons resonantly heated. Particle-in-cell simulation shows that when applied to a thin slab, the process can produce intense two-cycle light pulses as well as long-lasting self-magnetic fields. PMID:27300997

  4. Control of transmission of right circularly polarized laser light in overdense plasma by applied magnetic field pulses

    NASA Astrophysics Data System (ADS)

    Ma, Guangjin; Yu, Wei; Yu, M. Y.; Luan, Shixia; Wu, Dong

    2016-05-01

    The effect of a transient magnetic field on right-hand circularly polarized (RHCP) laser light propagation in overcritical-density plasma is investigated. When the electron gyrofrequency is larger than the wave frequency, RHCP light can propagate along the external magnetic field in an overcritical density plasma without resonance or cutoff. However, when the magnetic field falls to below the cyclotron resonance point, the propagating laser pulse will be truncated and the local plasma electrons resonantly heated. Particle-in-cell simulation shows that when applied to a thin slab, the process can produce intense two-cycle light pulses as well as long-lasting self-magnetic fields.

  5. Applying programmatic risk assessment to nuclear materials stabilization R and D planning

    SciTech Connect

    Kenley, C.R.; Brown-van Hoozer, S.A.

    1997-10-01

    A systems engineering approach to programmatic risk assessment, derived from the aerospace industry, was applied to various stabilization technologies to assess their relative maturity and availability for use in stabilizing nuclear materials. The assessment provided valuable information for trading off available technologies and identified the at-risk technologies that will require close tracking by the Department of Energy (DOE) to mitigate programmatic risks.

  6. Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR.

    PubMed

    Balzan, Riccardo; Fernandes, Laetitia; Comment, Arnaud; Pidial, Laetitia; Tavitian, Bertrand; Vasos, Paul R

    2016-01-01

    The main limitation of NMR-based investigations is low sensitivity. This prompts for long acquisition times, thus preventing real-time NMR measurements of metabolic transformations. Hyperpolarization via dissolution DNP circumvents part of the sensitivity issues thanks to the large out-of-equilibrium nuclear magnetization stemming from the electron-to-nucleus spin polarization transfer. The high NMR signal obtained can be used to monitor chemical reactions in real time. The downside of hyperpolarized NMR resides in the limited time window available for signal acquisition, which is usually on the order of the nuclear spin longitudinal relaxation time constant, T1, or, in favorable cases, on the order of the relaxation time constant associated with the singlet-state of coupled nuclei, TLLS. Cellular uptake of endogenous molecules and metabolic rates can provide essential information on tumor development and drug response. Numerous previous hyperpolarized NMR studies have demonstrated the relevancy of pyruvate as a metabolic substrate for monitoring enzymatic activity in vivo. This work provides a detailed description of the experimental setup and methods required for the study of enzymatic reactions, in particular the pyruvate-to-lactate conversion rate in presence of lactate dehydrogenase (LDH), by hyperpolarized NMR. PMID:26967906

  7. Polar studies of the sphericity degree of V/HTR nuclear fuel particles

    SciTech Connect

    Robert-Inacio, F. . E-mail: frederique.robert@isen.fr; Boschet, C.; Charollais, F.

    2006-06-15

    Advanced nuclear power reactor designs such as (Very) High Temperature Reactors (V/HTR) employ TRISO fuel particles that typically have a sub-millimetre U-based fuel kernel coated with three isotropic ceramic layers-a layer of silicon carbide sandwiched between pyrocarbon layers of different density. Evaluation of the ceramic layer thickness and of the degree of sphericity of these typical nuclear fuel particles is required at each step of the fabrication, in order to estimate future fuel performance under irradiation conditions. This study is based on the image processing of polished cross-sections, realized near the equatorial plane. From these 2D images, some measurements are carried out, giving an estimation of the diameter values for a sample of particles at each step of the coating process. These values are then statistically extended to the third dimension in order to obtain the thickness of each layer and the degree of sphericity of each particle. A representation of diameter and layer thickness in polar coordinates enables one to identify steps for which the coating process is defective or deviating from nominal objectives.

  8. Operational Characteristics of a 14-W 140-GHz Gyrotron for Dynamic Nuclear Polarization

    PubMed Central

    Joye, Colin D.; Griffin, Robert G.; Hornstein, Melissa K.; Hu, Kan-Nian; Kreischer, Kenneth E.; Rosay, Melanie; Shapiro, Michael A.; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Woskov, Paul P.

    2006-01-01

    The operating characteristics of a 140-GHz 14-W long pulse gyrotron are presented. The device is being used in dynamic nuclear polarization enhanced nuclear magnetic resonance (DNP/NMR) spectroscopy experiments. The gyrotron yields 14 W peak power at 139.65 GHz from the TE(0,3) operating mode using a 12.3-kV 25-mA electron beam. Additionally, up to 12 W peak has been observed in the TE(2,3) mode at 136.90 GHz. A series of mode converters transform the TE(0,3) operating mode to the TE(1,1) mode. Experimental results are compared with nonlinear simulations and show reasonable agreement. The millimeter-wave output beam was imaged in a single shot using a pyroelectric camera. The mode patterns matched reasonably well to theory for both the TE(0,1) mode and the TE(1,1) mode. Repeatable mode patterns were obtained at intervals ranging from 0.8 s apart to 11 min apart at the output of the final mode converter. PMID:17431442

  9. Dynamic nuclear polarization-enhanced 13C NMR spectroscopy of static biological solids

    NASA Astrophysics Data System (ADS)

    Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2013-06-01

    We explore the possibility of using dynamic nuclear polarization (DNP) to enhance signals in structural studies of biological solids by solid state NMR without sample spinning. Specifically, we use 2D 13C-13C exchange spectroscopy to probe the peptide backbone torsion angles (ϕ, ψ) in a series of selectively 13C-labeled 40-residue β-amyloid (Aβ1-40) samples, in both fibrillar and non-fibrillar states. Experiments are carried out at 9.39 T and 8 K, using a static double-resonance NMR probe and low-power microwave irradiation at 264 GHz. In frozen solutions of Aβ1-40 fibrils doped with DOTOPA-TEMPO, we observe DNP signal enhancement factors of 16-21. We show that the orientation- and frequency-dependent spin polarization exchange between sequential backbone carbonyl 13C labels can be simulated accurately using a simple expression for the exchange rate, after experimentally determined homogeneous 13C lineshapes are incorporated in the simulations. The experimental 2D 13C-13C exchange spectra place constraints on the ϕ and ψ angles between the two carbonyl labels. Although the data are not sufficient to determine ϕ and ψ uniquely, the data do provide non-trivial constraints that could be included in structure calculations. With DNP at low temperatures, 2D 13C-13C exchange spectra can be obtained from a 3.5 mg sample of Aβ1-40 fibrils in 4 h or less, despite the broad 13C chemical shift anisotropy line shapes that are observed in static samples.

  10. Dynamic nuclear polarization-enhanced 13C NMR spectroscopy of static biological solids

    PubMed Central

    Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2013-01-01

    We explore the possibility of using dynamic nuclear polarization (DNP) to enhance signals in structural studies of biological solids by solid state NMR without sample spinning. Specifically, we use 2D 13C-13C exchange spectroscopy to probe the peptide backbone torsion angles (ϕ,ψ) in a series of selectively 13C-labeled 40-residue β-amyloid (Aβ1–40) samples, in both fibrillar and non-fibrillar states. Experiments are carried out at 9.39 T and 8 K, using a static double-resonance NMR probe and low-power microwave irradiation at 264 GHz. In frozen solutions of Aβ1–40 fibrils doped with DOTOPA-TEMPO, we observe DNP signal enhancement factors of 16–21. We show that the orientation- and frequency-dependent spin polarization exchange between sequential backbone carbonyl 13C labels can be simulated accurately using a simple expression for the exchange rate, after experimentally determined homogeneous 13C lineshapes are incorporated in the simulations. The experimental 2D 13C-13C exchange spectra place constraints on the ϕ and ψ angles between the two carbonyl labels. Although the data are not sufficient to determine ϕ and ψ uniquely, the data do provide non-trivial constraints that could be included in structure calculations. With DNP at low temperatures, 2D 13C-13C exchange spectra can be obtained from a 3.5 mg sample of Aβ1–40 fibrils in 4 hr or less, despite the broad 13C chemical shift anisotropy line shapes that are observed in static samples. PMID:23562665

  11. Microwave Field Distribution in a Magic Angle Spinning Dynamic Nuclear Polarization NMR Probe

    PubMed Central

    Nanni, Emilio A.; Barnes, Alexander B.; Matsuki, Yoh; Woskov, Paul P.; Corzilius, Björn; Griffin, Robert G.; Temkin, Richard J.

    2011-01-01

    We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B1S) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4 mm diameter sapphire rotor containing the sample. The predicted average B1S field is 13µT/W1/2, where S denotes the electron spin. For a routinely achievable input power of 5 W the corresponding value is γ SB1S = 0.84 MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement (ε) vs. ω1S/(2π) for a sample of 13C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment. PMID:21382733

  12. Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods

    SciTech Connect

    Keating, Kristina; Slater, Lee; Ntarlagiannis, Dimitris; Williams, Kenneth H.

    2015-02-24

    This documents contains the final report for the project "Integrated Geophysical Measurements for Bioremediation Monitoring: Combining Spectral Induced Polarization, Nuclear Magnetic Resonance and Magnetic Methods" (DE-SC0007049) Executive Summary: Our research aimed to develop borehole measurement techniques capable of monitoring subsurface processes, such as changes in pore geometry and iron/sulfur geochemistry, associated with remediation of heavy metals and radionuclides. Previous work has demonstrated that geophysical method spectral induced polarization (SIP) can be used to assess subsurface contaminant remediation; however, SIP signals can be generated from multiple sources limiting their interpretation value. Integrating multiple geophysical methods, such as nuclear magnetic resonance (NMR) and magnetic susceptibility (MS), with SIP, could reduce the ambiguity of interpretation that might result from a single method. Our research efforts entails combining measurements from these methods, each sensitive to different mineral forms and/or mineral-fluid interfaces, providing better constraints on changes in subsurface biogeochemical processes and pore geometries significantly improving our understanding of processes impacting contaminant remediation. The Rifle Integrated Field Research Challenge (IFRC) site was used as a test location for our measurements. The Rifle IFRC site is located at a former uranium ore-processing facility in Rifle, Colorado. Leachate from spent mill tailings has resulted in residual uranium contamination of both groundwater and sediments within the local aquifer. Studies at the site include an ongoing acetate amendment strategy, native microbial populations are stimulated by introduction of carbon intended to alter redox conditions and immobilize uranium. To test the geophysical methods in the field, NMR and MS logging measurements were collected before, during, and after acetate amendment. Next, laboratory NMR, MS, and SIP measurements

  13. Regulatory experience in applying a radiological environmental protection framework for existing and planned nuclear facilities.

    PubMed

    Mihok, S; Thompson, P

    2012-01-01

    Frameworks and methods for the radiological protection of non-human biota have been evolving rapidly at the International Commission on Radiological Protection and through various European initiatives. The International Atomic Energy Agency has incorporated a requirement for environmental protection in the latest revision of its Basic Safety Standards. In Canada, the Canadian Nuclear Safety Commission has been legally obligated to prevent unreasonable risk to the environment since 2000. Licensees have therefore been meeting generic legal requirements to demonstrate adequate control of releases of radioactive substances for the protection of both people and biota for many years. In the USA, in addition to the generic requirements of the Environmental Protection Agency and the Nuclear Regulatory Commission, Department of Energy facilities have also had to comply with specific dose limits after a standard assessment methodology was finalised in 2002. Canadian regulators developed a similar framework for biota dose assessment through a regulatory assessment under the Canadian Environmental Protection Act in the late 1990s. Since then, this framework has been applied extensively to satisfy legal requirements under the Canadian Environmental Assessment Act and the Nuclear Safety and Control Act. After approximately a decade of experience in applying these methods, it is clear that simple methods are fit for purpose, and can be used for making regulatory decisions for existing and planned nuclear facilities.

  14. On The Potential of Dynamic Nuclear Polarization Enhanced Diamonds in Solid-State and Dissolution (13) C NMR Spectroscopy.

    PubMed

    Bretschneider, Christian O; Akbey, Ümit; Aussenac, Fabien; Olsen, Greg L; Feintuch, Akiva; Oschkinat, Hartmut; Frydman, Lucio

    2016-09-01

    Dynamic nuclear polarization (DNP) is a versatile option to improve the sensitivity of NMR and MRI. This versatility has elicited interest for overcoming potential limitations of these techniques, including the achievement of solid-state polarization enhancement at ambient conditions, and the maximization of (13) C signal lifetimes for performing in vivo MRI scans. This study explores whether diamond's (13) C behavior in nano- and micro-particles could be used to achieve these ends. The characteristics of diamond's DNP enhancement were analyzed for different magnetic fields, grain sizes, and sample environments ranging from cryogenic to ambient temperatures, in both solution and solid-state experiments. It was found that (13) C NMR signals could be boosted by orders of magnitude in either low- or room-temperature solid-state DNP experiments by utilizing naturally occurring paramagnetic P1 substitutional nitrogen defects. We attribute this behavior to the unusually long electronic/nuclear spin-lattice relaxation times characteristic of diamond, coupled with a time-independent cross-effect-like polarization transfer mechanism facilitated by a matching of the nitrogen-related hyperfine coupling and the (13) C Zeeman splitting. The efficiency of this solid-state polarization process, however, is harder to exploit in dissolution DNP-enhanced MRI contexts. The prospects for utilizing polarized diamond approaching nanoscale dimensions for both solid and solution applications are briefly discussed. PMID:27416769

  15. On The Potential of Dynamic Nuclear Polarization Enhanced Diamonds in Solid-State and Dissolution (13) C NMR Spectroscopy.

    PubMed

    Bretschneider, Christian O; Akbey, Ümit; Aussenac, Fabien; Olsen, Greg L; Feintuch, Akiva; Oschkinat, Hartmut; Frydman, Lucio

    2016-09-01

    Dynamic nuclear polarization (DNP) is a versatile option to improve the sensitivity of NMR and MRI. This versatility has elicited interest for overcoming potential limitations of these techniques, including the achievement of solid-state polarization enhancement at ambient conditions, and the maximization of (13) C signal lifetimes for performing in vivo MRI scans. This study explores whether diamond's (13) C behavior in nano- and micro-particles could be used to achieve these ends. The characteristics of diamond's DNP enhancement were analyzed for different magnetic fields, grain sizes, and sample environments ranging from cryogenic to ambient temperatures, in both solution and solid-state experiments. It was found that (13) C NMR signals could be boosted by orders of magnitude in either low- or room-temperature solid-state DNP experiments by utilizing naturally occurring paramagnetic P1 substitutional nitrogen defects. We attribute this behavior to the unusually long electronic/nuclear spin-lattice relaxation times characteristic of diamond, coupled with a time-independent cross-effect-like polarization transfer mechanism facilitated by a matching of the nitrogen-related hyperfine coupling and the (13) C Zeeman splitting. The efficiency of this solid-state polarization process, however, is harder to exploit in dissolution DNP-enhanced MRI contexts. The prospects for utilizing polarized diamond approaching nanoscale dimensions for both solid and solution applications are briefly discussed.

  16. Neutron Transfer Reactions: Surrogates for Neutron Capture for Basic and Applied Nuclear Science

    NASA Astrophysics Data System (ADS)

    Cizewski, J. A.; Jones, K. L.; Kozub, R. L.; Pain, S. D.; Peters, W. A.; Adekola, A.; Allen, J.; Bardayan, D. W.; Becker, J. A.; Blackmon, J. C.; Chae, K. Y.; Chipps, K. A.; Erikson, L.; Gaddis, A.; Harlin, C.; Hatarik, R.; Howard, J.; Jandel, M.; Johnson, M. S.; Kapler, R.; Krolas, W.; Liang, F.; Livesay, R. J.; Ma, Z.; Matei, C.; Matthews, C.; Moazen, B.; Nesaraja, C. D.; O'Malley, P.; Patterson, N.; Paulauskas, S. V.; Pelham, T.; Pittman, S. T.; Radford, D.; Rogers, J.; Schmitt, K.; Shapira, D.; Shriner, J. F.; Sissom, D. J.; Smith, M. S.; Swan, T.; Thomas, J. S.; Vieira, D. J.; Wilhelmy, J. B.; Wilson, G. L.

    2009-03-01

    Neutron capture reactions on unstable nuclei are important for both basic and applied nuclear science. A program has been developed at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory to study single-neutron transfer (d,p) reactions with rare isotope beams to provide information on neutron-induced reactions on unstable nuclei. Results from (d,p) studies on 130,132Sn, 134Te and 75As are discussed.

  17. Neutron transfer reactions: Surrogates for neutron capture for basic and applied nuclear science

    SciTech Connect

    Cizewski, J. A.; Jones, K. L.; Kozub, R. L.; Pain, Steven D; Peters, W. A.; Adekola, Aderemi S; Allen, J.; Bardayan, Daniel W; Becker, J.; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Erikson, Luke; Gaddis, A. L.; Harlin, Christopher W; Hatarik, Robert; Howard, Joshua A; Jandel, M.; Johnson, Micah; Kapler, R.; Krolas, W.; Liang, J Felix; Livesay, Jake; Ma, Zhanwen; Matei, Catalin; Matthews, C.; Moazen, Brian; Nesaraja, Caroline D; O'Malley, Patrick; Patterson, N. P.; Paulauskas, Stanley; Pelham, T.; Pittman, S. T.; Radford, David C; Rogers, J.; Schmitt, Kyle; Shapira, Dan; ShrinerJr., J. F.; Sissom, D. J.; Smith, Michael Scott; Swan, T. P.; Thomas, J. S.; Vieira, D. J.; Wilhelmy, J. B.; Wilson, Gemma L

    2009-04-01

    Neutron capture reactions on unstable nuclei are important for both basic and applied nuclear science. A program has been developed at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory to study single-neutron transfer (d,p) reactions with rare isotope beams to provide information on neutron-induced reactions on unstable nuclei. Results from (d,p) studies on {sup 130,132}Sn, {sup 134}Te and {sup 75}As are discussed.

  18. Development and performance of a 129-GHz dynamic nuclear polarizer in an ultra-wide bore superconducting magnet

    PubMed Central

    Lumata, Lloyd L.; Martin, Richard; Jindal, Ashish K.; Kovacs, Zoltan; Conradi, Mark S.

    2014-01-01

    Objective We sought to build a dynamic nuclear polarization system for operation at 4.6 T (129 GHz) and evaluate its efficiency in terms of 13C polarization levels using free radicals that span a range of ESR linewidths. Materials and methods A liquid helium cryostat was placed in a 4.6 T superconducting magnet with a 150-mm warm bore diameter. A 129-GHz microwave source was used to irradiate 13C enriched samples. Temperatures close to 1 K were achieved using a vacuum pump with a 453-m3/h roots blower. A hyperpolarized 13C nuclear magnetic resonance (NMR) signal was detected using a saddle coil and a Varian VNMRS console operating at 49.208 MHz. Samples doped with free radicals BDPA (1,3-bisdipheny-lene-2-phenylallyl), trityl OX063 (tris{8-carboxyl-2,2,6,6-benzo(1,2-d:4,5-d)-bis(1,3)dithiole-4-yl}methyl sodium salt), galvinoxyl ((2,6-di-tert-butyl-α-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene)-p-tolyloxy), 2,2-diphenylpicrylhydrazyl (DPPH) and 4-oxo-TEMPO (4-Oxo-2,2,6,6-tetramethyl-1-piperidinyloxy) were assayed. Microwave dynamic nuclear polarization (DNP) spectra and solid-state 13C polarization levels for these samples were determined. Results 13C polarization levels close to 50 % were achieved for [1-13C]pyruvic acid at 1.15 K using the narrow electron spin resonance (ESR) linewidth free radicals trityl OX063 and BDPA, while 10–20 % 13C polarizations were achieved using galvinoxyl, DPPH and 4-oxo-TEMPO. Conclusion At this field strength free radicals with smaller ESR linewidths are still superior for DNP of 13C as opposed to those with linewidths that exceed that of the 1H Larmor frequency. PMID:25120071

  19. A Spectrometer for Dynamic Nuclear Polarization and Electron Paramagnetic Resonance at High Frequencies

    NASA Astrophysics Data System (ADS)

    Becerra, L. R.; Gerfen, G. J.; Bellew, B. F.; Bryant, J. A.; Hall, D. A.; Inati, S. J.; Weber, R. T.; Un, S.; Prisner, T. F.; McDermott, A. E.; Fishbein, K. W.; Kreischer, K. E.; Temkin, R. J.; Singel, D. J.; Griffin, R. G.

    A high-frequency dynamic nuclear polarization (DNP)/electron paramagnetic resonance spectrometer operating at 211 MHz for 1H and 140 GHz for g= 2 paramagnetic centers (5 T static field) is described. The salient feature of the instrument is a cyclotron-resonance maser (gyrotron) which generates high-frequency, high-power microwave radiation. This gyrotron, which under conventional operation produces millisecond pulses at kilowatt powers, has been adapted to operate at ˜100 W for 1 to 20 s pulses and in the continuous wave mode at the 10 W power level. Experiments combining DNP with magic-angle spinning (MAS) nuclear magnetic resonance were performed on samples consisting of 2% by weight of the free radical BDPA doped into polystyrene. Room-temperature DNP enhancement factors of 10 for 1H and 40 for 13C were obtained in the NMR-MAS spectra. Static DNP NMR has also been performed on samples containing nitroxides dissolved in water:glycerol solvent mixtures. Enhancements of approximately 200 have been obtained for low-temperature (14 K) 1H NMR. A pulsed/CW EPR spectrometer operating at 140 GHz has been developed in conjunction with the DNP spectrometer. Microwave sources include Gunn-diode oscillators which provide low-power (20 mW) radiation, and the gyrotron, which has been used to deliver higher power levels in pulsed experiments. Results using this spectrometer are presented for continuous-wave and echo-detected EPR, electron spin-echo-envelope modulation (ESEEM), and Fourier-transform EPR.

  20. Frequency swept microwaves for hyperfine decoupling and time domain dynamic nuclear polarization.

    PubMed

    Hoff, Daniel E M; Albert, Brice J; Saliba, Edward P; Scott, Faith J; Choi, Eric J; Mardini, Michael; Barnes, Alexander B

    2015-11-01

    Hyperfine decoupling and pulsed dynamic nuclear polarization (DNP) are promising techniques to improve high field DNP NMR. We explore experimental and theoretical considerations to implement them with magic angle spinning (MAS). Microwave field simulations using the high frequency structural simulator (HFSS) software suite are performed to characterize the inhomogeneous phase independent microwave field throughout a 198GHz MAS DNP probe. Our calculations show that a microwave power input of 17W is required to generate an average EPR nutation frequency of 0.84MHz. We also present a detailed calculation of microwave heating from the HFSS parameters and find that 7.1% of the incident microwave power contributes to dielectric sample heating. Voltage tunable gyrotron oscillators are proposed as a class of frequency agile microwave sources to generate microwave frequency sweeps required for the frequency modulated cross effect, electron spin inversions, and hyperfine decoupling. Electron spin inversions of stable organic radicals are simulated with SPINEVOLUTION using the inhomogeneous microwave fields calculated by HFSS. We calculate an electron spin inversion efficiency of 56% at a spinning frequency of 5kHz. Finally, we demonstrate gyrotron acceleration potentials required to generate swept microwave frequency profiles for the frequency modulated cross effect and electron spin inversions.

  1. A spinning thermometer to monitor microwave heating and glass transitions in dynamic nuclear polarization.

    PubMed

    Miéville, Pascal; Vitzthum, Veronika; Caporini, Marc A; Jannin, Sami; Gerber-Lemaire, Sandrine; Bodenhausen, Geoffrey

    2011-11-01

    As previously demonstrated by Thurber and Tycko, the peak position of (79)Br in potassium bromide (KBr) allows one to determine the temperature of a spinning sample. We propose to adapt the original design by using a compact KBr tablet placed at the bottom of the magic angle spinning rotor, separated from the sample under investigation by a thin disk made of polytetrafluoroethylene (or 'Teflon'®). This design allows spinning the sample up to at least 16 kHz. The KBr tablet can remain in the rotor when changing the sample under investigation. Calibration in the range of 98 < T < 320 K has been carried out in a static rotor by inserting a platinum thermometer. The accuracy is better than ± 0.9 K, even in the presence of microwave irradiation. Irradiation with 5 W microwaves at 263 GHz leads to a small temperature increase of 3.6 ± 1.4 K in either static or spinning samples. The dynamic nuclear polarization enhancement decreases with increasing temperature, in particular when a frozen glassy sample undergoes a glass transition.

  2. Dynamic nuclear polarization-magnetic resonance imaging at low ESR irradiation frequency for ascorbyl free radicals

    PubMed Central

    Ito, Shinji; Hyodo, Fuminori

    2016-01-01

    Highly water-soluble ubiquinone-0 (CoQ0) reacts with ascorbate monoanion (Asc) to mediate the production of ascorbyl free radicals (AFR). Using aqueous reaction mixture of CoQ0 and Asc, we obtained positively enhanced dynamic nuclear polarization (DNP)-magnetic resonance (MR) images of the AFR at low frequency (ranging from 515 to 530 MHz) of electron spin resonance (ESR) irradiation. The shape of the determined DNP spectrum was similar to ESR absorption spectra with doublet spectral peaks. The relative locational relationship of spectral peaks in the DNP spectra between the AFR (520 and 525 MHz), 14N-labeled carbamoyl-PROXYL (14N-CmP) (526.5 MHz), and Oxo63 (522 MHz) was different from that in the X-band ESR spectra, but were similar to that in the 300-MHz ESR spectra. The ratio of DNP enhancement to radical concentration for the AFR was higher than those for 14N-CmP, Oxo63, and flavin semiquinone radicals. The spectroscopic DNP properties observed for the AFR were essentially the same as those for AFR mediated by pyrroloquinoline quinone. Moreover, we made a success of in vivo DNP-MR imaging of the CoQ0-mediated AFR which was administered by the subcutaneous and oral injections as an imaging probe. PMID:26892591

  3. Cryogenic sample exchange NMR probe for magic angle spinning dynamic nuclear polarization

    PubMed Central

    Barnes, Alexander B.; Mak-Jurkauskas, Melody L.; Matsuki, Yoh; Bajaj, Vikram S.; van der Wel, Patrick C. A.; DeRocher, Ronald; Bryant, Jeffrey; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Lugtenburg, Johan; Herzfeld, Judith; Griffin, Robert G.

    2009-01-01

    We describe a cryogenic sample exchange system that dramatically improves the efficiency of magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments by reducing the time required to change samples and by improving long-term instrument stability. Changing samples in conventional cryogenic MAS DNP/NMR experiments involves warming the probe to room temperature, detaching all cryogenic, RF, and microwave connections, removing the probe from the magnet, replacing the sample, and reversing all the previous steps, with the entire cycle requiring a few hours. The sample exchange system described here — which relies on an eject pipe attached to the front of the MAS stator and a vacuum jacketed dewar with a bellowed hole — circumvents these procedures. To demonstrate the excellent sensitivity, resolution, and stability achieved with this quadruple resonance sample exchange probe, we have performed high precision distance measurements on the active site of the membrane protein bacteriorhodopsin. We also include a spectrum of the tripeptide N-f-MLF-OH at 100 K which shows 30 Hz linewidths. PMID:19356957

  4. Frequency swept microwaves for hyperfine decoupling and time domain dynamic nuclear polarization

    PubMed Central

    Hoff, Daniel E.M.; Albert, Brice J.; Saliba, Edward P.; Scott, Faith J.; Choi, Eric J.; Mardini, Michael; Barnes, Alexander B.

    2015-01-01

    Hyperfine decoupling and pulsed dynamic nuclear polarization (DNP) are promising techniques to improve high field DNP NMR. We explore experimental and theoretical considerations to implement them with magic angle spinning (MAS). Microwave field simulations using the high frequency structural simulator (HFSS) software suite are performed to characterize the inhomogeneous phase independent microwave field throughout a 198 GHz MAS DNP probe. Our calculations show that a microwave power input of 17 W is required to generate an average EPR nutation frequency of 0.84 MHz. We also present a detailed calculation of microwave heating from the HFSS parameters and find that 7.1% of the incident microwave power contributes to dielectric sample heating. Voltage tunable gyrotron oscillators are proposed as a class of frequency agile microwave sources to generate microwave frequency sweeps required for the frequency modulated cross effect, electron spin inversions, and hyperfine decoupling. Electron spin inversions of stable organic radicals are simulated with SPINEVOLUTION using the inhomogeneous microwave fields calculated by HFSS. We calculate an electron spin inversion efficiency of 56% at a spinning frequency of 5 kHz. Finally, we demonstrate gyrotron acceleration potentials required to generate swept microwave frequency profiles for the frequency modulated cross effect and electron spin inversions. PMID:26482131

  5. Free Radical Imaging Using In Vivo Dynamic Nuclear Polarization-MRI.

    PubMed

    Utsumi, Hideo; Hyodo, Fuminori

    2015-01-01

    Redox reactions that generate free radical intermediates are essential to metabolic processes, and their intermediates can produce reactive oxygen species, which may promote diseases related to oxidative stress. The development of an in vivo electron spin resonance (ESR) spectrometer and its imaging enables us noninvasive and direct measurement of in vivo free radical reactions in living organisms. The dynamic nuclear polarization magnetic resonance imaging (DNP-MRI), also called PEDRI or OMRI, is also a new imaging method for observing free radical species in vivo. The spatiotemporal resolution of free radical imaging with DNP-MRI is comparable with that in MRI, and each of the radical species can be distinguished in the spectroscopic images by changing the frequency or magnetic field of ESR irradiation. Several kinds of stable nitroxyl radicals were used as spin probes to detect in vivo redox reactions. The signal decay of nitroxyl probes, which is determined with in vivo DNP-MRI, reflects the redox status under oxidative stress, and the signal decay is suppressed by prior administration of antioxidants. In addition, DNP-MRI can also visualize various intermediate free radicals from the intrinsic redox molecules. This noninvasive method, in vivo DNP-MRI, could become a useful tool for investigating the mechanism of oxidative injuries in animal disease models and the in vivo effects of antioxidant drugs.

  6. 7Li relaxation time measurements at very low magnetic field by 1H dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Zeghib, Nadir; Grucker, Daniel

    2001-09-01

    Dynamic nuclear polarization (DNP) of water protons was used to measure the relaxation time of lithium at very low magnetic field as a demonstration of the use of DNP for nuclei less abundant than water protons. Lithium (Li+) was chosen because it is an efficient treatment for manic-depressive illness, with an unknown action mechanism. After having recalled the theoretical basis of a three-spin system comprising two nuclei - the water proton of the solvent, the dissolved Li+ ion and the free electron of a free radical - we have developed a transient solution in order to optimize potential biological applications of Li DNP. The three-spin model has allowed computation of all the parameters of the system - the longitudinal relaxation rate per unit of free radical concentration, the dipolar and scalar part of the coupling between the nuclei and the electron, and the maximum signal enhancement achievable for both proton and lithium spins. All these measurements have been obtained solely through the detection of the proton resonance.

  7. Dynamic nuclear polarization-magnetic resonance imaging at low ESR irradiation frequency for ascorbyl free radicals

    NASA Astrophysics Data System (ADS)

    Ito, Shinji; Hyodo, Fuminori

    2016-02-01

    Highly water-soluble ubiquinone-0 (CoQ0) reacts with ascorbate monoanion (Asc) to mediate the production of ascorbyl free radicals (AFR). Using aqueous reaction mixture of CoQ0 and Asc, we obtained positively enhanced dynamic nuclear polarization (DNP)-magnetic resonance (MR) images of the AFR at low frequency (ranging from 515 to 530 MHz) of electron spin resonance (ESR) irradiation. The shape of the determined DNP spectrum was similar to ESR absorption spectra with doublet spectral peaks. The relative locational relationship of spectral peaks in the DNP spectra between the AFR (520 and 525 MHz), 14N-labeled carbamoyl-PROXYL (14N-CmP) (526.5 MHz), and Oxo63 (522 MHz) was different from that in the X-band ESR spectra, but were similar to that in the 300-MHz ESR spectra. The ratio of DNP enhancement to radical concentration for the AFR was higher than those for 14N-CmP, Oxo63, and flavin semiquinone radicals. The spectroscopic DNP properties observed for the AFR were essentially the same as those for AFR mediated by pyrroloquinoline quinone. Moreover, we made a success of in vivo DNP-MR imaging of the CoQ0-mediated AFR which was administered by the subcutaneous and oral injections as an imaging probe.

  8. Amplifying Dynamic Nuclear Polarization of Frozen Solutions by Incorporating Dielectric Particles

    PubMed Central

    2014-01-01

    There is currently great interest in understanding the limits on NMR signal enhancements provided by dynamic nuclear polarization (DNP), and in particular if the theoretical maximum enhancements can be achieved. We show that over a 2-fold improvement in cross-effect DNP enhancements can be achieved in MAS experiments on frozen solutions by simply incorporating solid particles into the sample. At 9.4 T and ∼105 K, enhancements up to εH = 515 are obtained in this way, corresponding to 78% of the theoretical maximum. We also underline that degassing of the sample is important to achieve highest enhancements. We link the amplification effect to the dielectric properties of the solid material, which probably gives rise to scattering, diffraction, and amplification of the microwave field in the sample. This is substantiated by simulations of microwave propagation. A reduction in sample heating at a given microwave power also likely occurs due to reduced dielectric loss. Simulations indicate that the microwave field (and thus the DNP enhancement) is inhomogeneous in the sample, and we deduce that in these experiments between 5 and 10% of the solution actually yields the theoretical maximum signal enhancement of 658. The effect is demonstrated for a variety of particles added to both aqueous and organic biradical solutions. PMID:25285480

  9. Causation's nuclear future: applying proportional liability to the Price-Anderson Act.

    PubMed

    O'Connell, William D

    2014-11-01

    For more than a quarter century, public discourse has pushed the nuclear-power industry in the direction of heavier regulation and greater scrutiny, effectively halting construction of new reactors. By focusing on contemporary fear of significant accidents, such discourse begs the question of what the nation's court system would actually do should a major nuclear incident cause radiation-induced cancers. Congress's attempt to answer that question is the Price-Anderson Act, a broad statute addressing claims by the victims of a major nuclear accident. Lower courts interpreting the Act have repeatedly encountered a major stumbling block: it declares that judges must apply the antediluvian preponderance-of-the-evidence logic of state tort law, even though radiation science insists that the causes of radiation-induced cancers are more complex. After a major nuclear accident, the Act's paradoxically outdated rules for adjudicating "causation" would make post-incident compensation unworkable. This Note urges that nuclear-power-plant liability should not turn on eighteenth-century tort law. Drawing on modern scientific conclusions regarding the invariably "statistical" nature of cancer, this Note suggests a unitary federal standard for the Price-Anderson Act--that a defendant be deemed to have "caused" a plaintiff's injury in direct proportion to the increased risk of harm the defendant has imposed. This "proportional liability" rule would not only fairly evaluate the costs borne by injured plaintiffs and protect a reawakening nuclear industry from the prospect of bank-breaking litigation, but would prove workable with only minor changes to the Price-Anderson Act's standards of "injury" and "fault."

  10. EPR detected polarization transfer between Gd3+ and protons at low temperature and 3.3 T: the first step of dynamic nuclear polarization.

    PubMed

    Nagarajan, Vijayasarathi; Hovav, Yonatan; Feintuch, Akiva; Vega, Shimon; Goldfarb, Daniella

    2010-06-01

    Electron-electron double resonance pulsed electron paramagnetic resonance (EPR) at 95 GHz (3.3 T) is used to follow the dynamics of the electron spin polarization during the first stages of dynamic nuclear polarization in solids. The experiments were performed on a frozen solution of Gd(+3) (S=7/2) in water/glycerol. Focusing on the central vector -1/2 --> vector +1/2 transition we measured the polarization transfer from the Gd(3+) electron spin to the adjacent (1)H protons. The dependence of the echo detected EPR signal on the length of the microwave irradiation at the EPR "forbidden" transition corresponding to an electron and a proton spin flip is measured for different powers, showing dynamics on the microsecond to millisecond time scales. A theoretical model based on the spin density matrix formalism is suggested to account for this dynamics. The central transition of the Gd(3+) ion is considered as an effective S = 1/2 system and is coupled to (1)H (I = 1/2) nuclei. Simulations based on a single electron-single nucleus four level system are shown to deviate from the experimental results and an alternative approach taking into account the more realistic multinuclei picture is shown to agree qualitatively with the experiments.

  11. Fast characterization of functionalized silica materials by silicon-29 surface-enhanced NMR spectroscopy using dynamic nuclear polarization.

    PubMed

    Lelli, Moreno; Gajan, David; Lesage, Anne; Caporini, Marc A; Vitzthum, Veronika; Miéville, Pascal; Héroguel, Florent; Rascón, Fernando; Roussey, Arthur; Thieuleux, Chloé; Boualleg, Malika; Veyre, Laurent; Bodenhausen, Geoffrey; Copéret, Christophe; Emsley, Lyndon

    2011-02-23

    We demonstrate fast characterization of the distribution of surface bonding modes and interactions in a series of functionalized materials via surface-enhanced nuclear magnetic resonance spectroscopy using dynamic nuclear polarization (DNP). Surface-enhanced silicon-29 DNP NMR spectra were obtained by using incipient wetness impregnation of the sample with a solution containing a polarizing radical (TOTAPOL). We identify and compare the bonding topology of functional groups in materials obtained via a sol-gel process and in materials prepared by post-grafting reactions. Furthermore, the remarkable gain in time provided by surface-enhanced silicon-29 DNP NMR spectroscopy (typically on the order of a factor 400) allows the facile acquisition of two-dimensional correlation spectra. PMID:21280606

  12. Low-temperature dynamic nuclear polarization with helium-cooled samples and nitrogen-driven magic-angle spinning.

    PubMed

    Thurber, Kent; Tycko, Robert

    2016-03-01

    We describe novel instrumentation for low-temperature solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS), focusing on aspects of this instrumentation that have not been described in detail in previous publications. We characterize the performance of an extended interaction oscillator (EIO) microwave source, operating near 264 GHz with 1.5 W output power, which we use in conjunction with a quasi-optical microwave polarizing system and a MAS NMR probe that employs liquid helium for sample cooling and nitrogen gas for sample spinning. Enhancement factors for cross-polarized (13)C NMR signals in the 100-200 range are demonstrated with DNP at 25K. The dependences of signal amplitudes on sample temperature, as well as microwave power, polarization, and frequency, are presented. We show that sample temperatures below 30K can be achieved with helium consumption rates below 1.3 l/h. To illustrate potential applications of this instrumentation in structural studies of biochemical systems, we compare results from low-temperature DNP experiments on a calmodulin-binding peptide in its free and bound states.

  13. Low-temperature dynamic nuclear polarization with helium-cooled samples and nitrogen-driven magic-angle spinning.

    PubMed

    Thurber, Kent; Tycko, Robert

    2016-03-01

    We describe novel instrumentation for low-temperature solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS), focusing on aspects of this instrumentation that have not been described in detail in previous publications. We characterize the performance of an extended interaction oscillator (EIO) microwave source, operating near 264 GHz with 1.5 W output power, which we use in conjunction with a quasi-optical microwave polarizing system and a MAS NMR probe that employs liquid helium for sample cooling and nitrogen gas for sample spinning. Enhancement factors for cross-polarized (13)C NMR signals in the 100-200 range are demonstrated with DNP at 25K. The dependences of signal amplitudes on sample temperature, as well as microwave power, polarization, and frequency, are presented. We show that sample temperatures below 30K can be achieved with helium consumption rates below 1.3 l/h. To illustrate potential applications of this instrumentation in structural studies of biochemical systems, we compare results from low-temperature DNP experiments on a calmodulin-binding peptide in its free and bound states. PMID:26920835

  14. Low-temperature dynamic nuclear polarization with helium-cooled samples and nitrogen-driven magic-angle spinning

    NASA Astrophysics Data System (ADS)

    Thurber, Kent; Tycko, Robert

    2016-03-01

    We describe novel instrumentation for low-temperature solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS), focusing on aspects of this instrumentation that have not been described in detail in previous publications. We characterize the performance of an extended interaction oscillator (EIO) microwave source, operating near 264 GHz with 1.5 W output power, which we use in conjunction with a quasi-optical microwave polarizing system and a MAS NMR probe that employs liquid helium for sample cooling and nitrogen gas for sample spinning. Enhancement factors for cross-polarized 13C NMR signals in the 100-200 range are demonstrated with DNP at 25 K. The dependences of signal amplitudes on sample temperature, as well as microwave power, polarization, and frequency, are presented. We show that sample temperatures below 30 K can be achieved with helium consumption rates below 1.3 l/h. To illustrate potential applications of this instrumentation in structural studies of biochemical systems, we compare results from low-temperature DNP experiments on a calmodulin-binding peptide in its free and bound states.

  15. Protonation of carbon single-walled nanotubes studied using 13C and 1H-13C cross polarization nuclear magnetic resonance and Raman spectroscopies.

    PubMed

    Engtrakul, Chaiwat; Davis, Mark F; Gennett, Thomas; Dillon, Anne C; Jones, Kim M; Heben, Michael J

    2005-12-14

    The reversible protonation of carbon single-walled nanotubes (SWNTs) in sulfuric acid and Nafion was investigated using solid-state nuclear magnetic resonance (NMR) and Raman spectroscopies. Magic-angle spinning (MAS) was used to obtain high-resolution 13C and 1H-13C cross polarization (CP) NMR spectra. The 13C NMR chemical shifts are reported for bulk SWNTs, H2SO4-treated SWNTs, SWNT-Nafion polymer composites, SWNT-AQ55 polymer composites, and SWNTs in contact with water. Protonation occurs without irreversible oxidation of the nanotube substrate via a charge-transfer process. This is the first report of a chemically induced change in a SWNT 13C resonance brought about by a reversible interaction with an acidic proton, providing additional evidence that carbon nanotubes behave as weak bases. Cross polarization was found to be a powerful technique for providing an additional contrast mechanism for studying nanotubes in contact with other chemical species. The CP studies confirmed polarization transfer from nearby protons to nanotube carbon atoms. The CP technique was also applied to investigate water adsorbed on carbon nanotube surfaces. Finally, the degree of bundling of the SWNTs in Nafion films was probed with the 1H-13C CP-MAS technique. PMID:16332107

  16. Characterization of organic contaminants in porous media using nuclear magnetic resonance and spectral induced polarization measurements.

    NASA Astrophysics Data System (ADS)

    Rupert, Y. K.

    2015-12-01

    The remediation and monitoring of soils and groundwater contaminated with organic compounds is an important goal of many environmental restoration efforts. This laboratory research focuses on combining two innovative geophysical methods: nuclear magnetic resonance (NMR) and spectral induced polarization (SIP) to assess their suitability to characterize and quantify organic contaminants in porous media. Toluene, a light non-aqueous phase liquid (LNAPL), and ethoxy-nonafluorobutane, an engineered dense non-aqueous phase liquid (DNAPL), have been selected as representative organic contaminants. Low-field NMR relaxation time (T2) measurements and diffusion-relaxation (D-T2) correlation measurements, as well as low frequency SIP measurements (<10 kHz) are performed to quantify the amount of these two organic compounds in the presence of water in three types of porous media (sands, clay, and various sand-clay mixtures). The T2, D-T2, and SIP measurements are made on water, toluene, and the synthetic DNAPL in each porous media to understand the effect of different porous media on the NMR and SIP responses in each fluid. We then plan to make measurements on water-organic mixtures with varied concentrations of organic compounds in each porous medium to resolve the NMR and SIP response of the organic contaminants from that of water and to quantify the amount of organic contaminants. Building a relationship between SIP and NMR signatures from organic contaminants not only provides a fundamental yet important petrophysical relationship, but also builds a framework for continued investigation into how these two methods synergize. This will also provide spatially dense information about organic contaminated natural sediments at scales that will improve the quantitative characterization and remediation of contaminated sites.The remediation and monitoring of soils and groundwater contaminated with organic compounds is an important goal of many environmental restoration efforts

  17. Characterizing petrophysical properties of carbonate rocks using nuclear magnetic resonance and spectral induced polarization

    NASA Astrophysics Data System (ADS)

    Zhang, Fan; Zhang, Chi; Rankey, Eugene

    2016-04-01

    Unlike sandstones, with well-characterized correlations between porosity and permeability, carbonate rocks are well known for their highly complex petrophysical behaviors due to their intrinsically heterogeneous pore shape, pore size, and pore distributions and connectivity. The characterization of petrophysical properties of carbonate rocks, including rock properties and rock-fluid interactions, remains big challenges. This laboratory study focuses on integrating two geophysical methods: nuclear magnetic resonance (NMR) and spectral induced polarization (SIP) to determine porosity, pore size distribution, and permeability of carbonate rocks. NMR measures the relaxation of hydrogen nuclei at pore scale. Samples with different pore structures saturated by fluids have molecular relaxation responses to the external magnetic field which could generate various NMR signals. Permeability estimation from NMR in siliciclastic rocks is routine, however, is problematic in carbonates. SIP determines complex resistivity of a sample across a wide range of frequency and is sensitive to variations in the properties of solid-fluid and fluid-fluid interfaces in porous media. Previous studies investigated the relationships between permeability and parameters derived from SIP data, but are restricted to narrow lithology range. Our study used carbonate core samples from three depositional environments: tidal zone, shallow marine, and platform/reef margin of an atoll. Samples were fully saturated by water for T2 relaxation measurements and complex conductivity measurements at low frequencies. We compare the pore volume to surface area ratio measured from NMR and SIP and assess the applicability of established petrophysical models to estimate permeability from NMR and SIP data. We hope to build a relationship between NMR signals, SIP responses and petrophysical properties in carbonate rocks. The results could also provide new data and help further understand the unique and complex pore

  18. Dynamic nuclear polarization-enhanced 1H-13C double resonance NMR in static samples below 20 K

    NASA Astrophysics Data System (ADS)

    Potapov, Alexey; Thurber, Kent R.; Yau, Wai-Ming; Tycko, Robert

    2012-08-01

    We demonstrate the feasibility of one-dimensional and two-dimensional 1H-13C double resonance NMR experiments with dynamic nuclear polarization (DNP) at 9.4 T and temperatures below 20 K, including both 1H-13C cross-polarization and 1H decoupling, and discuss the effects of polarizing agent type, polarizing agent concentration, temperature, and solvent deuteration. We describe a two-channel low-temperature DNP/NMR probe, capable of carrying the radio-frequency power load required for 1H-13C cross-polarization and high-power proton decoupling. Experiments at 8 K and 16 K reveal a significant T2 relaxation of 13C, induced by electron spin flips. Carr-Purcell experiments and numerical simulations of Carr-Purcell dephasing curves allow us to determine the effective correlation time of electron flips under our experimental conditions. The dependence of the DNP signal enhancement on electron spin concentration shows a maximum near 80 mM. Although no significant difference in the absolute DNP enhancements for triradical (DOTOPA-TEMPO) and biradical (TOTAPOL) dopants was found, the triradical produced greater DNP build-up rates, which are advantageous for DNP experiments. Additionally the feasibility of structural measurements on 13C-labeled biomolecules was demonstrated with a two-dimensional 13C-13C exchange spectrum of selectively 13C-labeled β-amyloid fibrils.

  19. Dynamic nuclear polarization-enhanced 1H–13C double resonance NMR in static samples below 20 K

    PubMed Central

    Potapov, Alexey; Thurber, Kent R.; Yau, Wai-Ming; Tycko, Robert

    2012-01-01

    We demonstrate the feasibility of one-dimensional and two-dimensional 1H–13C double resonance NMR experiments with dynamic nuclear polarization (DNP) at 9.4 T and temperatures below 20 K, including both 1H–13C cross-polarization and 1H decoupling, and discuss the effects of polarizing agent type, polarizing agent concentration, temperature, and solvent deuteration. We describe a two-channel low-temperature DNP/NMR probe, capable of carrying the radio-frequency power load required for 1H–13C cross-polarization and high-power proton decoupling. Experiments at 8 K and 16 K reveal a significant T2 relaxation of 13C, induced by electron spin flips. Carr–Purcell experiments and numerical simulations of Carr–Purcell dephasing curves allow us to determine the effective correlation time of electron flips under our experimental conditions. The dependence of the DNP signal enhancement on electron spin concentration shows a maximum near 80 mM. Although no significant difference in the absolute DNP enhancements for triradical (DOTOPA-TEMPO) and biradical (TOTAPOL) dopants was found, the triradical produced greater DNP build-up rates, which are advantageous for DNP experiments. Additionally the feasibility of structural measurements on 13C-labeled biomolecules was demonstrated with a two-dimensional 13C–13C exchange spectrum of selectively 13C-labeled β-amyloid fibrils. PMID:22743540

  20. Dynamic nuclear polarization-enhanced ¹H-¹³C double resonance NMR in static samples below 20 K.

    PubMed

    Potapov, Alexey; Thurber, Kent R; Yau, Wai-Ming; Tycko, Robert

    2012-08-01

    We demonstrate the feasibility of one-dimensional and two-dimensional ¹H-¹³C double resonance NMR experiments with dynamic nuclear polarization (DNP) at 9.4 T and temperatures below 20 K, including both ¹H-¹³C cross-polarization and ¹H decoupling, and discuss the effects of polarizing agent type, polarizing agent concentration, temperature, and solvent deuteration. We describe a two-channel low-temperature DNP/NMR probe, capable of carrying the radio-frequency power load required for ¹H-¹³C cross-polarization and high-power proton decoupling. Experiments at 8 K and 16 K reveal a significant T₂ relaxation of ¹³C, induced by electron spin flips. Carr-Purcell experiments and numerical simulations of Carr-Purcell dephasing curves allow us to determine the effective correlation time of electron flips under our experimental conditions. The dependence of the DNP signal enhancement on electron spin concentration shows a maximum near 80 mM. Although no significant difference in the absolute DNP enhancements for triradical (DOTOPA-TEMPO) and biradical (TOTAPOL) dopants was found, the triradical produced greater DNP build-up rates, which are advantageous for DNP experiments. Additionally the feasibility of structural measurements on ¹³C-labeled biomolecules was demonstrated with a two-dimensional ¹³C-¹³C exchange spectrum of selectively ¹³C-labeled β-amyloid fibrils. PMID:22743540

  1. Applying programmatic risk assessment to nuclear materials stabilization R and D planning

    SciTech Connect

    Brown-Van Hoozer, S.A.; Kenley, C.R.

    1997-10-01

    A systems engineering approach to programmatic risk assessment, derived from the aerospace industry, was applied to various stabilization technologies to assess their relative maturity and availability for use in stabilizing nuclear materials. The assessment provided valuable information for trading off available technologies and identified the at-risk technologies that will require close tracking by the Department of Energy (DOE) to mitigate programmatic risks. This paper presents the programmatic risk assessment methodology developed for the 1995 R and D Plan and updated for the 1996 R and D Plan. Results of the 1996 assessment also are presented (DOE/ID-10561, 1996).

  2. ⁵⁷Fe polarization-dependent synchrotron Mössbauer spectroscopy using a diamond phase plate and an iron borate nuclear Bragg monochromator.

    PubMed

    Mitsui, Takaya; Imai, Yasuhiko; Masuda, Ryo; Seto, Makoto; Mibu, Ko

    2015-03-01

    Energy-domain (57)Fe polarization-dependent synchrotron radiation Mössbauer spectroscopy was developed by using a diamond X-ray phase plate and an iron borate nuclear Bragg monochromator. The former controls the polarization of the incident synchrotron radiation X-rays and the latter filters the (57)Fe-Mössbauer radiation with a narrow bandwidth of ∼3.4 Γ0 (Γ0 ≃ 4.7 neV: natural linewidth of the (57)Fe nucleus) from the broadband synchrotron radiation. The developed nuclear diffraction optics allowed (57)Fe-Mössbauer studies to be performed with various polarization states, i.e. linear polarization, circular polarization and non-polarization. In this paper, the spectrometer system, beam characterization, performance-test experiments and a grazing-incidence Mössbauer measurement of an isotope-enriched ((57)Fe: 95%) iron thin film are described. PMID:25723944

  3. The role of the glassy dynamics and thermal mixing in the dynamic nuclear polarization and relaxation mechanisms of pyruvic acid.

    PubMed

    Filibian, M; Colombo Serra, S; Moscardini, M; Rosso, A; Tedoldi, F; Carretta, P

    2014-12-28

    The temperature dependence of (1)H and (13)C nuclear spin-lattice relaxation rate 1/T1 has been studied in the 1.6-4.2 K temperature range in pure pyruvic acid and in pyruvic acid containing trityl radicals at a concentration of 15 mM. The temperature dependence of 1/T1 is found to follow a quadratic power law for both nuclei in the two samples. Remarkably the same temperature dependence is displayed also by the electron spin-lattice relaxation rate 1/T1e in the sample containing radicals. These results are explained by considering the effect of the structural dynamics on the relaxation rates in pyruvic acid. Dynamic nuclear polarization experiments show that below 4 K the (13)C build up rate scales with 1/T1e, in analogy to (13)C 1/T1 and consistently with a thermal mixing scenario where all the electrons are collectively involved in the dynamic nuclear polarization process and the nuclear spin reservoir is in good thermal contact with the electron spin system.

  4. Non-destructive research methods applied on materials for the new generation of nuclear reactors

    NASA Astrophysics Data System (ADS)

    Bartošová, I.; Slugeň, V.; Veterníková, J.; Sojak, S.; Petriska, M.; Bouhaddane, A.

    2014-06-01

    The paper is aimed on non-destructive experimental techniques applied on materials for the new generation of nuclear reactors (GEN IV). With the development of these reactors, also materials have to be developed in order to guarantee high standard properties needed for construction. These properties are high temperature resistance, radiation resistance and resistance to other negative effects. Nevertheless the changes in their mechanical properties should be only minimal. Materials, that fulfil these requirements, are analysed in this work. The ferritic-martensitic (FM) steels and ODS steels are studied in details. Microstructural defects, which can occur in structural materials and can be also accumulated during irradiation due to neutron flux or alpha, beta and gamma radiation, were analysed using different spectroscopic methods as positron annihilation spectroscopy and Barkhausen noise, which were applied for measurements of three different FM steels (T91, P91 and E97) as well as one ODS steel (ODS Eurofer).

  5. Common cause evaluations in applied risk analysis of nuclear power plants. [PWR

    SciTech Connect

    Taniguchi, T.; Ligon, D.; Stamatelatos, M.

    1983-04-01

    Qualitative and quantitative approaches were developed for the evaluation of common cause failures (CCFs) in nuclear power plants and were applied to the analysis of the auxiliary feedwater systems of several pressurized water reactors (PWRs). Key CCF variables were identified through a survey of experts in the field and a review of failure experience in operating PWRs. These variables were classified into categories of high, medium, and low defense against a CCF. Based on the results, a checklist was developed for analyzing CCFs of systems. Several known techniques for quantifying CCFs were also reviewed. The information provided valuable insights in the development of a new model for estimating CCF probabilities, which is an extension of and improvement over the Beta Factor method. As applied to the analysis of the PWR auxiliary feedwater systems, the method yielded much more realistic values than the original Beta Factor method for a one-out-of-three system.

  6. Sensitivity Analysis Applied to the Validation of the 10 B Capture Reaction in Nuclear Fuel Casks

    SciTech Connect

    Goluoglu, S

    2004-03-18

    Boron has commonly been used in nuclear fuel casks to ensure a sufficient margin of subcriticality. The amount of boron used in most casks far exceeds the amount of boron present in any of the available benchmark experiments. Such heavy loadings of boron in the casks may result in considerable spectral differences as compared to the benchmarks, resulting in boron sensitivities that are very different from those of the benchmarks. Before the calculations to determine the nuclear safety margin for various fuel loadings are deemed acceptable, as part of the safety basis, the computer code and cross sections must be validated against experimental benchmarks that cover the area of applicability of the proposed cask design. Therefore, this study was performed to determine if these available benchmarks can be used to validate a criticality code and neutron cross sections for the fuel casks. The sensitivity/uncertainty methodology has been applied to several application cask systems with different boron areal densities. Although, the sensitivities of the nuclear fuel cask applications are not completely covered by the set of benchmarks that were used in this study with regard to the 10B capture cross section, the effect of this lack of coverage on the keff is minimal. Thus, the experimental biases are determined to be appropriate for the cask systems, and no additional bias (penalty) due to high boron loading need be imposed.

  7. Synthesis and evaluation of nitroxide-based oligoradicals for low-temperature dynamic nuclear polarization in solid state NMR.

    PubMed

    Yau, Wai-Ming; Thurber, Kent R; Tycko, Robert

    2014-07-01

    We describe the synthesis of new nitroxide-based biradical, triradical, and tetraradical compounds and the evaluation of their performance as paramagnetic dopants in dynamic nuclear polarization (DNP) experiments in solid state nuclear magnetic resonance (NMR) spectroscopy with magic-angle spinning (MAS). Under our experimental conditions, which include temperatures in the 25-30 K range, a 9.4 T magnetic field, MAS frequencies of 6.2-6.8 kHz, and microwave irradiation at 264.0 GHz from a 800 mW extended interaction oscillator source, the most effective compounds are triradicals that are related to the previously-described compound DOTOPA-TEMPO (see Thurber et al., 2010), but have improved solubility in glycerol/water solvent near neutral pH. Using these compounds at 30 mM total nitroxide concentration, we observe DNP enhancement factors of 92-128 for cross-polarized (13)C NMR signals from (15)N,(13)C-labeled melittin in partially protonated glycerol/water, and build-up times of 2.6-3.8s for (1)H spin polarizations. Net sensitivity enhancements with biradical and tetraradical dopants, taking into account absolute (13)C NMR signal amplitudes and build-up times, are approximately 2-4 times lower than with the best triradicals. PMID:24887201

  8. Synthesis and evaluation of nitroxide-based oligoradicals for low-temperature dynamic nuclear polarization in solid state NMR

    NASA Astrophysics Data System (ADS)

    Yau, Wai-Ming; Thurber, Kent R.; Tycko, Robert

    2014-07-01

    We describe the synthesis of new nitroxide-based biradical, triradical, and tetraradical compounds and the evaluation of their performance as paramagnetic dopants in dynamic nuclear polarization (DNP) experiments in solid state nuclear magnetic resonance (NMR) spectroscopy with magic-angle spinning (MAS). Under our experimental conditions, which include temperatures in the 25-30 K range, a 9.4 T magnetic field, MAS frequencies of 6.2-6.8 kHz, and microwave irradiation at 264.0 GHz from a 800 mW extended interaction oscillator source, the most effective compounds are triradicals that are related to the previously-described compound DOTOPA-TEMPO (see Thurber et al., 2010), but have improved solubility in glycerol/water solvent near neutral pH. Using these compounds at 30 mM total nitroxide concentration, we observe DNP enhancement factors of 92-128 for cross-polarized 13C NMR signals from 15N,13C-labeled melittin in partially protonated glycerol/water, and build-up times of 2.6-3.8 s for 1H spin polarizations. Net sensitivity enhancements with biradical and tetraradical dopants, taking into account absolute 13C NMR signal amplitudes and build-up times, are approximately 2-4 times lower than with the best triradicals.

  9. Synthesis and evaluation of nitroxide-based oligoradicals for low-temperature dynamic nuclear polarization in solid state NMR

    PubMed Central

    Yau, Wai-Ming; Thurber, Kent R.; Tycko, Robert

    2014-01-01

    We describe the synthesis of new nitroxide-based biradical, triradical, and tetraradical compounds and the evaluation of their performance as paramagnetic dopants in dynamic nuclear polarization (DNP) experiments in solid state nuclear magnetic resonance (NMR) spectroscopy with magic-angle spinning (MAS). Under our experimental conditions, which include temperatures in the 25–30 K range, a 9.4 T magnetic field, MAS frequencies of 6.2–6.8 kHz, and microwave irradiation at 264.0 GHz from a 800 mW extended interaction oscillator source, the most effective compounds are triradicals that are related to the previously-described compound DOTOPA-TEMPO (see Thurber et al., 2010), but have improved solubility in glycerol/water solvent near neutral pH. Using these compounds at 30 mM total nitroxide concentration, we observe DNP enhancement factors of 92–128 for cross-polarized 13C NMR signals from 15N,13C-labeled melittin in partially protonated glycerol/water, and build-up times of 2.6–3.8 s for 1H spin polarizations. Net sensitivity enhancements with biradical and tetraradical dopants, taking into account absolute 13C NMR signal amplitudes and build-up times, are approximately 2–4 times lower than with the best triradicals. PMID:24887201

  10. Monitoring microbial growth and activity using spectral induced polarization and low-field nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Keating, Kristina; Revil, Andre

    2015-04-01

    Microbes and microbial activities in the Earth's subsurface play a significant role in shaping subsurface environments and are involved in environmental applications such as remediation of contaminants in groundwater and oil fields biodegradation. Stimulated microbial growth in such applications could cause wide variety of changes of physical/chemical properties in the subsurface. It is critical to monitor and determine the fate and transportation of microorganisms in the subsurface during such applications. Recent geophysical studies demonstrate the potential of two innovative techniques, spectral induced polarization (SIP) and low-field nuclear magnetic resonance (NMR), for monitoring microbial growth and activities in porous media. The SIP measures complex dielectric properties of porous media at low frequencies of exciting electric field, and NMR studies the porous structure of geologic media and characterizes fluids subsurface. In this laboratory study, we examined both SIP and NMR responses from bacterial growth suspension as well as suspension mixed with silica sands. We focus on the direct contribution of microbes to the SIP and NMR signals in the absence of biofilm formation or biomineralization. We used Zymomonas mobilis and Shewanella oneidensis (MR-1) for SIP and NMR measurements, respectively. The SIP measurements were collected over the frequency range of 0.1 - 1 kHz on Z. mobilis growth suspension and suspension saturated sands at different cell densities. SIP data show two distinct peaks in imaginary conductivity spectra, and both imaginary and real conductivities increased as microbial density increased. NMR data were collected using both CPMG pulse sequence and D-T2 mapping to determine the T2-distribution and diffusion properties on S. oneidensis suspension, pellets (live and dead), and suspension mixed with silica sands. NMR data show a decrease in the T2-distribution in S. oneidensis suspension saturated sands as microbial density increase. A

  11. Proceedings of the LAMPF workshop on physics with polarized nuclear targets

    SciTech Connect

    Burleson, G.; Gibbs, W.; Hoffmann, G.; Jarmer, J.J.; Tanaka, N.

    1986-08-01

    Topics of discussion included static and dynamic methods for polarizing nuclei, proton and pion nucleus scattering experiments, and possible future experiments at LAMPF. Separate abstracts were prepared for 11 papers in this report. (DWL)

  12. Development of Neutron Polarization Measurement System for Studying NN interaction in Nuclear Medium

    NASA Astrophysics Data System (ADS)

    Yasuda, J.; Wakasa, T.; Dozono, M.; Fukunaga, T.; Gotanda, S.; Hatanaka, K.; Kanaya, Y.; Maeda, Y.; Maeda, Y.; Miki, K.; Nishio, Y.; Noro, T.; Ohnaka, K.; Sakaguchi, S.; Sakemi, Y.; Sekiguchi, K.; Tamii, A.; Taguchi, T.; Wada, Y.

    2016-02-01

    We have developed the neutron polarization measurement system to perform the first polarization-transfer measurement for the exclusive (p,np) reaction. For the neutron polarization measurement, we have reconstructed the neutron polarimeter NPOL3. The NPOL3 system has been calibrated by using the polarized neutron from the 2H(p→,n→) reaction, and the resulting effective analyzing power is Ay:eff = 0.127. For the exclusive measurement, the Large Acceptance Spectrometer (LAS) has been used for the recoil proton detection. The energy resolution of 6 MeV is achieved for separation energy, which is sufficient to separate the 1s and 1p orbits for light nuclei.

  13. Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves

    PubMed Central

    Thurber, Kent R.; Tycko, Robert

    2014-01-01

    We report solid state 13C and 1H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, 1H and cross-polarized 13C NMR signals from 15N,13C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations. PMID:24832263

  14. Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves.

    PubMed

    Thurber, Kent R; Tycko, Robert

    2014-05-14

    We report solid state (13)C and (1)H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, (1)H and cross-polarized (13)C NMR signals from (15)N,(13)C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations. PMID:24832263

  15. Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves

    NASA Astrophysics Data System (ADS)

    Thurber, Kent R.; Tycko, Robert

    2014-05-01

    We report solid state 13C and 1H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, 1H and cross-polarized 13C NMR signals from 15N,13C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations.

  16. Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves.

    PubMed

    Thurber, Kent R; Tycko, Robert

    2014-05-14

    We report solid state (13)C and (1)H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, (1)H and cross-polarized (13)C NMR signals from (15)N,(13)C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations.

  17. Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves

    SciTech Connect

    Thurber, Kent R. Tycko, Robert

    2014-05-14

    We report solid state {sup 13}C and {sup 1}H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, {sup 1}H and cross-polarized {sup 13}C NMR signals from {sup 15}N,{sup 13}C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T{sub 1e} is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations.

  18. Comparative study of nuclear effects in polarized electron scattering from 3 He

    SciTech Connect

    Ethier, J. J.; Melnitchouk, W.

    2013-11-01

    We present a detailed analysis of nuclear effects in inclusive electron scattering from polarized 3He nuclei for polarization asymmetries, structure functions and their moments, both in the nucleon resonance and deep-inelastic regions. We compare the results of calculations within the weak binding approximation at finite Q2 with the effective polarization ansatz often used in experimental data analyses, and explore the impact of Δ components in the nuclear wave function and nucleon off-shell corrections on extractions of the free neutron structure. Using the same framework we also make predictions for the Q2 dependence of quasielastic scattering from polarized 3He, data on which can be used to constrain the spin-dependent nuclear smearing functions in 3He.

  19. Enhancement of the Two-Dimensional Conduction Electron Zeeman Energy Near v=1 by Optical Dynamic Nuclear Polarization

    SciTech Connect

    Bowers, C.R.; Reno, J.L.; Simmons, J.A.; Vitkalov, S.A.

    1998-11-06

    Enhancement of the Zeeman energy of 2D conduction electrons near v = 1 by optical dynamic nuclear polarization (lINP), as observed by the Overhauser shift of the transport detected electron spin resonance, is measured quantitatively for the first time in GaAs/AIGaAs mukiquantum wells. The NMR signal enhancement is obtained under similar conditions in the same sample, allowing the hyperke coupling constant of 3.7T between between the nuclei and 2D conduction electrons to be measured for the first time. The potential to suppress the Zeeman energy by optical DNP is discussed in the context of its potential influence on Skyrmion formation.

  20. 187Re - 187Os Nuclear Geochronometry: A New Dating Method Applied to Old Ores

    NASA Astrophysics Data System (ADS)

    Roller, Goetz

    2015-04-01

    187Re - 187Os nuclear geochronometry is a newly developed dating method especially (but not only) for PGE hosting magmatic ore deposits. It combines ideas of nuclear astrophysics with geochronology. For this, the concept of sudden nucleosynthesis [1-3] is used to calculate so-called nucleogeochronometric Rhenium-Osmium two-point-isochrone (TPI) ages. Here, the method is applied to the Sudbury Igneous Complex (SIC) and the Stillwater Complex (SC), using a set of two nuclear geochronometers. They are named the BARBERTON ( Re/Os = 0.849, 187Os/186Os = 10.04 ± 0.015 [4]) and the IVREA (Re/Os = 0.951, 187Os/186Os = 1.9360 ± 0.0015 [5]) nuclear geochronometer. Calculated TPI ages are consistent with results from Sm-Nd geochronology, a previously published Re-Os Molybdenum age of 2740 ± 80 Ma for the G-chromitite of the SC [6] and a Re-Os isochrone age of 1689 ± 160 Ma for the Strathcona ores of the SIC [7]. This leads to an alternative explanation of the peculiar and enigmatic 187Os/186Osi isotopic signatures reported from both ore deposits. For example, for a TPI age of 2717 ± 100 Ma the Ultramafic Series of the SC contains both extremely low (subchrondritic) 187Os/186Osi ratios (187Os/186Osi = 0.125 ± 0.067) and extremely radiogenic isotopic signatures (187Os/186Osi = 6.55 ± 1.7, [6]) in mineral separates (chromites) and whole rock samples, respectively. Within the Strathcona ores of the SIC, even more pronounced radiogenic 187Os/186Os initial ratios can be calculated for TPI ages between 1586 ± 63 Ma (187Os/186Osi = 8.998 ± 0.045) and 1733 ± 84 Ma (187Os/186Osi = 8.901 ± 0.059). These results are in line with the recalculated Re-Os isochrone age of 1689 ± 160 Ma (187Os/186Osi = 8.8 ± 2.3 [7]). In the light of nuclear geochronometry, the occurrence of such peculiar isotopic 187Os/186Osi signatures within one and the same lithological horizon are plausible if explained by mingling of the two nucleogeochronometric (BARBERTON and IVREA) reservoirs containing

  1. Sensitizing solid state nuclear magnetic resonance of dilute nuclei by spin-diffusion assisted polarization transfers.

    PubMed

    Lupulescu, Adonis; Frydman, Lucio

    2011-10-01

    Recent years have witnessed efforts geared at increasing the sensitivity of NMR experiments, by relying on the suitable tailoring and exploitation of relaxation phenomena. These efforts have included the use of paramagnetic agents, enhanced (1)H-(1)H incoherent and coherent transfers processes in 2D liquid state spectroscopy, and homonuclear (13)C-(13)C spin diffusion effects in labeled solids. The present study examines some of the opportunities that could open when exploiting spontaneous (1)H-(1)H spin-diffusion processes, to enhance relaxation and to improve the sensitivity of dilute nuclei in solid state NMR measurements. It is shown that polarization transfer experiments executed under sufficiently fast magic-angle-spinning conditions, enable a selective polarization of the dilute low-γ spins by their immediate neighboring protons. Repolarization of the latter can then occur during the time involved in monitoring the signal emitted by the low-γ nuclei. The basic features involved in the resulting approach, and its potential to improve the effective sensitivity of solid state NMR measurements on dilute nuclei, are analyzed. Experimental tests witness the advantages that could reside from utilizing this kind of approach over conventional cross-polarization processes. These measurements also highlight a number of limitations that will have to be overcome for transforming selective polarization transfers of this kind into analytical methods of choice.

  2. Impact of Ho(3+)-doping on (13)C dynamic nuclear polarization using trityl OX063 free radical.

    PubMed

    Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Kaur, Pavanjeet; Martins, André; Fidelino, Leila; Khemtong, Chalermchai; Song, Likai; Sherry, A Dean; Lumata, Lloyd

    2016-08-21

    We have investigated the effects of Ho-DOTA doping on the dynamic nuclear polarization (DNP) of [1-(13)C] sodium acetate using trityl OX063 free radical at 3.35 T and 1.2 K. Our results indicate that addition of 2 mM Ho-DOTA on 3 M [1-(13)C] sodium acetate sample in 1 : 1 v/v glycerol : water with 15 mM trityl OX063 improves the DNP-enhanced (13)C solid-state nuclear polarization by a factor of around 2.7-fold. Similar to the Gd(3+) doping effect on (13)C DNP, the locations of the positive and negative (13)C maximum polarization peaks in the (13)C microwave DNP sweep are shifted towards each other with the addition of Ho-DOTA on the DNP sample. W-band electron spin resonance (ESR) studies have revealed that while the shape and linewidth of the trityl OX063 ESR spectrum was not affected by Ho(3+)-doping, the electron spin-lattice relaxation time T1 of trityl OX063 was prominently reduced at cryogenic temperatures. The reduction of trityl OX063 electron T1 by Ho-doping is linked to the (13)C DNP improvement in light of the thermodynamic picture of DNP. Moreover, the presence of Ho-DOTA in the dissolution liquid at room temperature has negligible reduction effect on liquid-state (13)C T1, in contrast to Gd(3+)-doping which drastically reduces the (13)C T1. The results here suggest that Ho(3+)-doping is advantageous over Gd(3+) in terms of preservation of hyperpolarized state-an important aspect to consider for in vitro and in vivo NMR or imaging (MRI) experiments where a considerable preparation time is needed to administer the hyperpolarized (13)C liquid.

  3. Impact of Ho(3+)-doping on (13)C dynamic nuclear polarization using trityl OX063 free radical.

    PubMed

    Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Kaur, Pavanjeet; Martins, André; Fidelino, Leila; Khemtong, Chalermchai; Song, Likai; Sherry, A Dean; Lumata, Lloyd

    2016-08-21

    We have investigated the effects of Ho-DOTA doping on the dynamic nuclear polarization (DNP) of [1-(13)C] sodium acetate using trityl OX063 free radical at 3.35 T and 1.2 K. Our results indicate that addition of 2 mM Ho-DOTA on 3 M [1-(13)C] sodium acetate sample in 1 : 1 v/v glycerol : water with 15 mM trityl OX063 improves the DNP-enhanced (13)C solid-state nuclear polarization by a factor of around 2.7-fold. Similar to the Gd(3+) doping effect on (13)C DNP, the locations of the positive and negative (13)C maximum polarization peaks in the (13)C microwave DNP sweep are shifted towards each other with the addition of Ho-DOTA on the DNP sample. W-band electron spin resonance (ESR) studies have revealed that while the shape and linewidth of the trityl OX063 ESR spectrum was not affected by Ho(3+)-doping, the electron spin-lattice relaxation time T1 of trityl OX063 was prominently reduced at cryogenic temperatures. The reduction of trityl OX063 electron T1 by Ho-doping is linked to the (13)C DNP improvement in light of the thermodynamic picture of DNP. Moreover, the presence of Ho-DOTA in the dissolution liquid at room temperature has negligible reduction effect on liquid-state (13)C T1, in contrast to Gd(3+)-doping which drastically reduces the (13)C T1. The results here suggest that Ho(3+)-doping is advantageous over Gd(3+) in terms of preservation of hyperpolarized state-an important aspect to consider for in vitro and in vivo NMR or imaging (MRI) experiments where a considerable preparation time is needed to administer the hyperpolarized (13)C liquid. PMID:27424954

  4. Very Long Baseline Interferometry Applied to Polar Motion, Relativity and Geodesy. Ph.D. Thesis - Maryland Univ.

    NASA Technical Reports Server (NTRS)

    Ma, C.

    1978-01-01

    The causes and effects of diurnal polar motion are described. An algorithm is developed for modeling the effects on very long baseline interferometry observables. Five years of radio-frequency very long baseline interferometry data from stations in Massachusetts, California, and Sweden are analyzed for diurnal polar motion. It is found that the effect is larger than predicted by McClure. Corrections to the standard nutation series caused by the deformability of the earth have a significant effect on the estimated diurnal polar motion scaling factor and the post-fit residual scatter. Simulations of high precision very long baseline interferometry experiments taking into account both measurement uncertainty and modeled errors are described.

  5. NMR Investigation of Optical Polarization of Nuclear Spins in GaAs

    NASA Astrophysics Data System (ADS)

    Paravastu, Anant; Hayes, Sophia; Schwickert, Birgit; Reimer, Jeffrey; Dinh, Long; Balooch, Mehdi

    2003-03-01

    Light-induced nuclear spin alignments have been measured in GaAs as a function of photon energy, irradiation time, and sample temperature using NMR spectroscopy at 9.4 Tesla and 10 to 50 K. Significant optical enhancements were observed at a range of photon energies, starting just below the band gap and persisting through 100 meV above the gap. Irradiation above the band gap resulted in thermally activated NMR signal enhancements while sub band gap irradiation did not. Short and long irradiation time dependencies revealed insights into the nature of cross relaxation between electronic nuclear spins, contradicting mechanisms based on either localized electron-nuclear contact at defect sites or cross relaxation between nuclei and free electrons. We propose that the presence of a mobile or delocalized enabling electronic species characterized by a long electron-nuclear correlation time, such as an exciton, is necessary in any mechanism which explains the data.

  6. Applied Nuclear Accountability Systems: A Case Study in the System Architecture and Development of NuMAC

    SciTech Connect

    Campbell, Andrea Beth

    2004-07-01

    This is a case study of the NuMAC nuclear accountability system developed at a private fuel fabrication facility. This paper investigates nuclear material accountability and safeguards by researching expert knowledge applied in the system design and development. Presented is a system developed to detect and deter the theft of weapons grade nuclear material. Examined is the system architecture that includes: issues for the design and development of the system; stakeholder issues; how the system was built and evolved; software design, database design, and development tool considerations; security and computing ethics. (author)

  7. The Stewardship Science Academic Alliance: A Model of Education for Fundamental and Applied Low-energy Nuclear Science

    SciTech Connect

    Cizewski, J.A.

    2014-06-15

    The Stewardship Science Academic Alliances (SSAA) were inaugurated in 2002 by the National Nuclear Security Administration of the U. S. Department of Energy. The purpose is to enhance connections between NNSA laboratories and the activities of university scientists and their students in research areas important to NNSA, including low-energy nuclear science. This paper highlights some of the ways that the SSAA fosters education and training of graduate students and postdoctoral scholars in low-energy nuclear science, preparing them for careers in fundamental and applied research and development.

  8. Applied nuclear data research and development. Semiannual progress report, April 1-September 30, 1983

    SciTech Connect

    Arthur, E.D.

    1984-06-01

    This progress report describes the activities of the Los Alamos Nuclear Data Group for April 1, 1983 through September 30, 1983. Topics covered include theory and evaluation of nuclear cross sections; nuclear cross-section processing and testing; neutron activation; fission products, and actinides; and core neutronics code development in support of LMFBR carbide core assessment. (GHT)

  9. IAEA advisory group meeting on basic and applied problems of nuclear level densities

    SciTech Connect

    Bhat, M.R.

    1983-06-01

    Separate entries were made in the data base for 17 of the 19 papers included. Two papers were previously included in the data base. Workshop reports are included on (1) nuclear level density theories and nuclear model reaction cross-section calculations and (2) extraction of nuclear level density information from experimental data. (WHK)

  10. Spin-polarized /sup 3/He nuclear targets and metastable /sup 4/He atoms by optical pumping with a tunable, Nd:YAP laser

    SciTech Connect

    Bohler, C.L.; Schearer, L.D.; Leduc, M.; Nacher, P.J.; Zachorowski, L.; Milner, R.G.; McKeown, R.D.; Woodward, C.E.

    1988-04-15

    Several Nd:YAP lasers were constructed which could be broadly tuned in the 1083-nm region which includes the helium 2/sup 3/S-2/sup 3/P transition, using a Lyot filter and thin, uncoated etalons within the laser cavity. 1 W of power could be extracted at 1083 nm through a 1% transmitting output coupler. This laser beam was used to optically pump metastable /sup 4/He and /sup 3/He 2/sup 3/S helium atoms in a weak discharge cell, spin polarizing the metastable ensemble. In a /sup 3/He cell the polarization is transferred to the nuclear spin system. A /sup 3/He target cell at 0.3 Torr was polarized to 52% in a few minutes. We describe the application of this system to the design of polarized targets for experiments in nuclear physics.

  11. Applying the polarity rapid assessment method to characterize nitrosamine precursors and to understand their removal by drinking water treatment processes.

    PubMed

    Liao, Xiaobin; Bei, Er; Li, Shixiang; Ouyang, Yueying; Wang, Jun; Chen, Chao; Zhang, Xiaojian; Krasner, Stuart W; Suffet, I H Mel

    2015-12-15

    Some N-nitrosamines (NAs) have been identified as emerging disinfection by-products during water treatment. Thus, it is essential to understand the characteristics of the NA precursors. In this study, the polarity rapid assessment method (PRAM) and the classical resin fractionation method were studied as methods to fractionate the NA precursors during drinking water treatment. The results showed that PRAM has much higher selectivity for NA precursors than the resin approach. The normalized N-nitrosodimethylamine formation potential (NDMA FP) and N-nitrosodiethylamine (NDEA) FP of four resin fractions was at the same level as the average yield of the bulk organic matter whereas that of the cationic fraction by PRAM showed 50 times the average. Thus, the cationic fraction was shown to be the most important NDMA precursor contributor. The PRAM method also helped understand which portions of the NA precursor were removed by different water treatment processes. Activated carbon (AC) adsorption removed over 90% of the non-polar PRAM fraction (that sorbs onto the C18 solid phase extraction [SPE] cartridge) of NDMA and NDEA precursors. Bio-treatment removed 80-90% of the cationic fraction of PRAM (that is retained on the cation exchange SPE cartridge) and 40-60% of the non-cationic fractions. Ozonation removed 50-60% of the non-polar PRAM fraction of NA precursors and transformed part of them into the polar fraction. Coagulation and sedimentation had very limited removal of various PRAM fractions of NA precursors.

  12. Characterization of a nuclear compartment shared by nuclear bodies applying ectopic protein expression and correlative light and electron microscopy

    SciTech Connect

    Richter, Karsten; Reichenzeller, Michaela; Goerisch, Sabine M.; Schmidt, Ute; Scheuermann, Markus O.; Herrmann, Harald; Lichter, Peter . E-mail: m.macleod@dkfz.de

    2005-02-01

    To investigate the accessibility of interphase nuclei for nuclear body-sized particles, we analyzed in cultured cells from human origin by correlative fluorescence and electron microscopy (EM) the bundle-formation of Xenopus-vimentin targeted to the nucleus via a nuclear localization signal (NLS). Moreover, we investigated the spatial relationship of speckles, Cajal bodies, and crystalline particles formed by Mx1 fused to yellow fluorescent protein (YFP), with respect to these bundle arrays. At 37 deg C, the nucleus-targeted, temperature-sensitive Xenopus vimentin was deposited in focal accumulations. Upon shift to 28 deg C, polymerization was induced and filament arrays became visible. Within 2 h after temperature shift, arrays were found to be composed of filaments loosely embedded in the nucleoplasm. The filaments were restricted to limited areas of the nucleus between focal accumulations. Upon incubation at 28 deg C for several hours, NLS vimentin filaments formed bundles looping throughout the nuclei. Speckles and Cajal bodies frequently localized in direct neighborhood to vimentin bundles. Similarly, small crystalline particles formed by YFP-tagged Mx1 also located next to vimentin bundles. Taking into account that nuclear targeted vimentin locates in the interchromosomal domain (ICD), we conclude that nuclear body-sized particles share a common nuclear space which is controlled by higher order chromatin organization.

  13. Polarized Raman investigations of oriented animal muscle fibers affected by storage time applying a 671 nm diode laser

    NASA Astrophysics Data System (ADS)

    Al Ebrahim, Halah; Sowoidnich, Kay; Schmidt, Heinar; Kronfeldt, Heinz-Detlef

    2011-06-01

    Due to its analytical ability and sensitivity to molecular vibrations, Raman spectroscopy provides valuable information of the secondary structure of proteins. Moreover, polarized Raman spectroscopy is shown to be a useful instrument to investigate the structural changes resulting from the aging and spoilage process of meat. In this work, polarized Raman spectra were measured on oriented cuts of pork and turkey. Fresh meat slices were stored at 5 °C and measured for a consecutive time period of 10 days. A 671 nm microsystem diode laser was used as excitation light source. The laser power at the sample was 50 mW and the integration time of each Raman spectrum was set to 5 seconds. Measurements were performed with a laser beam orientation perpendicular to the long axis of the muscle fibers. In that arrangement, the fibers were aligned either parallel or perpendicular to the polarization direction of the laser source. By using the statistical method of principal components analysis (PCA), a clear separation of the meat samples can be found for fresh meat according to the orientation (parallel or perpendicular) using the first two principal components. During the storage period, this separation subsequently vanishes due to the aging process and due to an increase of the microbial spoilage of the meat surface. For the latter effect, a time-dependent distinction of the Raman spectra is presented as well. Furthermore, specific changes of conformation-sensitive Raman bands were recognized, notably a decrease of the intensities of α-helical protein conformation.

  14. Dynamic nuclear polarization enhanced nuclear magnetic resonance and electron spin resonance studies of hydration and local water dynamics in micelle and vesicle assemblies.

    PubMed

    McCarney, Evan R; Armstrong, Brandon D; Kausik, Ravinath; Han, Songi

    2008-09-16

    We present a unique analysis tool for the selective detection of local water inside soft molecular assemblies (hydrophobic cores, vesicular bilayers, and micellar structures) suspended in bulk water. Through the use of dynamic nuclear polarization (DNP), the (1)H NMR signal of water is amplified, as it interacts with stable radicals that possess approximately 658 times higher spin polarization. We utilized stable nitroxide radicals covalently attached along the hydrophobic tail of stearic acid molecules that incorporate themselves into surfactant-based micelle or vesicle structures. Here, we present a study of local water content and fluid viscosity inside oleate micelles and vesicles and Triton X-100 micelles to serve as model systems for soft molecular assemblies. This approach is unique because the amplification of the NMR signal is performed in bulk solution and under ambient conditions with site-specific spin labels that only detect the water that is directly interacting with the localized spin labels. Continuous wave (cw) electron spin resonance (ESR) analysis provides rotational dynamics of the spin-labeled molecular chain segments and local polarity parameters that can be related to hydration properties, whereas we show that DNP-enhanced (1)H NMR analysis of fluid samples directly provides translational water dynamics and permeability of the local environment probed by the spin label. Our technique therefore has the potential to become a powerful analysis tool, complementary to cw ESR, to study hydration characteristics of surfactant assemblies, lipid bilayers, or protein aggregates, where water dynamics is a key parameter of their structure and function. In this study, we find that there is significant penetration of water inside the oleate micelles with a higher average local water viscosity (approximately 1.8 cP) than in bulk water, and Triton X-100 micelles and oleate vesicle bilayers mostly exclude water while allowing for considerable surfactant chain

  15. Successive Stages of Amyloid-β Self-Assembly Characterized by Solid-State Nuclear Magnetic Resonance with Dynamic Nuclear Polarization.

    PubMed

    Potapov, Alexey; Yau, Wai-Ming; Ghirlando, Rodolfo; Thurber, Kent R; Tycko, Robert

    2015-07-01

    Self-assembly of amyloid-β (Aβ) peptides in human brain tissue leads to neurodegeneration in Alzheimer's disease (AD). Amyloid fibrils, whose structures have been extensively characterized by solid state nuclear magnetic resonance (ssNMR) and other methods, are the thermodynamic end point of Aβ self-assembly. Oligomeric and protofibrillar assemblies, whose structures are less well-understood, are also observed as intermediates in the assembly process in vitro and have been implicated as important neurotoxic species in AD. We report experiments in which the structural evolution of 40-residue Aβ (Aβ40) is monitored by ssNMR measurements on frozen solutions prepared at four successive stages of the self-assembly process. Measurements on transient intermediates are enabled by ssNMR signal enhancements from dynamic nuclear polarization (DNP) at temperatures below 30 K. DNP-enhanced ssNMR data reveal a monotonic increase in conformational order from an initial state comprised primarily of monomers and small oligomers in solution at high pH, to larger oligomers near neutral pH, to metastable protofibrils, and finally to fibrils. Surprisingly, the predominant molecular conformation, indicated by (13)C NMR chemical shifts and by side chain contacts between F19 and L34 residues, is qualitatively similar at all stages. However, the in-register parallel β-sheet supramolecular structure, indicated by intermolecular (13)C spin polarization transfers, does not develop before the fibril stage. This work represents the first application of DNP-enhanced ssNMR to the characterization of peptide or protein self-assembly intermediates. PMID:26068174

  16. A study of C-13-enriched chemical vapor deposited diamond film by means of C-13 nuclear magnetic resonance, electron paramagnetic resonance, and dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Lock, Herman; Wind, Robert A.; Maciel, Gary E.; Johnson, Curtis E.

    1993-09-01

    The results are presented of a study, based on EPR and various NMR techniques, of the effect on the nature of CVD diamond films of the addition of O2 to the methane-hydrogen mixture used to produce the film. The addition of oxygen to the feed gas results in a reduction of the number of unpaired electron spins, roughly from 10 exp 18 spins/g up to 10 exp 17 spins/g. There is a small aromatic signal in the dynamic nuclear polarization (DNP)-cross polarization (CP)-magic angle spinning (MAS) C-13 spectrum and a small peak at 28 ppm in the 14 T DP-MAS C-13 spectrum for only the diamond film sample grown without O2 present in the feed gas. The combination of DNP and CP at 1.4 T enables one to obtain a useful DNP-CP-MAS C-13 spectrum, ostensibly probing only the surface and intergrain boundary regions, in a matter of hours.

  17. An ancient role for nuclear beta-catenin in the evolution of axial polarity and germ layer segregation

    NASA Technical Reports Server (NTRS)

    Wikramanayake, Athula H.; Hong, Melanie; Lee, Patricia N.; Pang, Kevin; Byrum, Christine A.; Bince, Joanna M.; Xu, Ronghui; Martindale, Mark Q.

    2003-01-01

    The human oncogene beta-catenin is a bifunctional protein with critical roles in both cell adhesion and transcriptional regulation in the Wnt pathway. Wnt/beta-catenin signalling has been implicated in developmental processes as diverse as elaboration of embryonic polarity, formation of germ layers, neural patterning, spindle orientation and gap junction communication, but the ancestral function of beta-catenin remains unclear. In many animal embryos, activation of beta-catenin signalling occurs in blastomeres that mark the site of gastrulation and endomesoderm formation, raising the possibility that asymmetric activation of beta-catenin signalling specified embryonic polarity and segregated germ layers in the common ancestor of bilaterally symmetrical animals. To test whether nuclear translocation of beta-catenin is involved in axial identity and/or germ layer formation in 'pre-bilaterians', we examined the in vivo distribution, stability and function of beta-catenin protein in embryos of the sea anemone Nematostella vectensis (Cnidaria, Anthozoa). Here we show that N. vectensis beta-catenin is differentially stabilized along the oral-aboral axis, translocated into nuclei in cells at the site of gastrulation and used to specify entoderm, indicating an evolutionarily ancient role for this protein in early pattern formation.

  18. Strong nuclear ring currents and magnetic fields in pseudorotating OsH4 molecules induced by circularly polarized laser pulses.

    PubMed

    Barth, Ingo; Bressler, Christian; Koseki, Shiro; Manz, Jörn

    2012-06-01

    We design a circularly polarized laser pulse in the infrared frequency and femtosecond time domains, for excitation of the OsH(4) molecule in its first excited pseudorotational state of the triply-degenerate bend. The OsH(4) molecule need not be pre-oriented. After excitation, the central nucleus Os carries out pseudorotation about the axis parallel to the direction of propagation of the laser pulse. This pseudorotation causes a strong electric ring current with a value I=1.53 e fs(-1). The mean value of the radius of the ring current is very small, R=0.0031 a(0), where a(0) is the Bohr radius. According to the Biot-Savart law (|B(R=0)| ~I/R)), this nuclear ring current induces the strongest magnetic field predicted so far in molecules, with a central peak absolute value |B(R=0)| =623 T. To monitor the effect, we propose an IR-pump-X-ray-probe versus an X-ray-probe-only experiment, at the K- and L-edges of X-ray ionization. The results are based on the general quantum theory of excitations of pseudorotations in tetrahedral molecules AB(4), driven by a circularly polarized laser pulse. PMID:22389250

  19. Nuclear polarization and magnetic resonance of unstable sup 170 Tm with beta-ray radiation-detected optical pumping in solids

    SciTech Connect

    Shimomura, K.; Uemura, S.; Kohmoto, T.; Fukuda, Y.; Ito, S.; Okano, K.; Muramoto, T.; Hashi, T.; Matsuki, S. College of Liberal Arts, Kyoto University, Kyoto College of Liberal Arts, Kobe University, Kobe, Japan Radioisotope Research Center, Kyoto University, Kyoto Research Reactor Institute, Kyoto University, Kumatori College of Liberal Arts, Shiga University, Shiga Institute for Chemical Research, Kyoto University, Kyoto Research Center for Nuclear Physics, Osaka University, Osaka )

    1990-08-01

    Significant nuclear polarization of unstable {sup 170}Tm in Tm{sup 2+}:SrF{sub 2} has been achieved with optical pumping in solids. The hyperfine coupling constant of divalent {sup 170}Tm in SrF{sub 2} was thus measured for the first time in high precision with the beta-ray radiation detected magnetic resonance, thereby also determining the nuclear magnetic moment: 0.2476(16){mu}{sub {ital N}}.

  20. Nuclear reactor power as applied to a space-based radar mission

    NASA Technical Reports Server (NTRS)

    Jaffe, L.; Beatty, R.; Bhandari, P.; Chow, E.; Deininger, W.; Ewell, R.; Fujita, T.; Grossman, M.; Bloomfield, H.; Heller, J.

    1988-01-01

    A space-based radar mission and spacecraft are examined to determine system requirements for a 300 kWe space nuclear reactor power system. The spacecraft configuration and its orbit, launch vehicle, and propulsion are described. Mission profiles are addressed, and storage in assembly orbit is considered. Dynamics and attitude control and the problems of nuclear and thermal radiation are examined.

  1. Simultaneous measurement of X-ray diffraction and ferroelectric polarization data as a function of applied electric field and frequency.

    PubMed

    Wooldridge, Jenny; Ryding, Steph; Brown, Simon; Burnett, Tim L; Cain, Markys G; Cernik, Robert; Hino, Ricardo; Stewart, Mark; Thompson, Paul

    2012-09-01

    The characteristics of a new ferroelectric measurement system at the European Synchrotron Radiation Facility are presented. The electric-field-induced phase transitions of Pb(Mg(1/3)Nb(2/3))O(3)-xPbTiO(3) are determined via in situ measurements of electric polarization within the synchrotron diffraction beamline. Real-time data collection methods on single-crystal samples are employed as a function of frequency to determine the microstructural origin of piezoelectric effects within these materials, probing the dynamic ferroelectric response.

  2. Interaction of self-assembling beta-sheet peptides with phospholipid monolayers: the role of aggregation state, polarity, charge and applied field.

    PubMed

    Protopapa, Elisabeth; Maude, Steven; Aggeli, Amalia; Nelson, Andrew

    2009-03-01

    Studies of beta-sheet peptide/phospholipid interactions are important for an understanding of the folding of beta-sheet-rich membrane proteins and the action of antimicrobial and toxic peptides. Further, self-assembling peptides have numerous applications in medicine and therefore an insight is required into the relation between peptide molecular structure and biomembrane activity. We previously developed one of the simplest known model peptide systems which, above a critical concentration (c*) in solution, undergoes nucleated one-dimensional self-assembly from a monomeric random coil into a hierarchy of well defined beta-sheet structures. Here we examine the effects of peptide aggregation, polarity, charge, and applied field on peptide interactions with dioleoyl phosphatidylcholine (DOPC) monolayers using electrochemical techniques. The interactions of six systematically altered 11 residue beta-sheet tape-forming peptides were investigated. The following findings with respect to 11 residue beta-sheet peptide-DOPC interaction arose from the study: (i) The solution monomer peptide species is the monolayer active moeity. (ii) Amphiphilic peptides are more monolayer active than polar peptides in the absence of applied electric field. (iii) Positive charge on amphiphilic peptides facilitates monolayer interaction in the absence of applied electric field. (iv) Negative applied electric field facilitates monolayer interaction with positively charged amphiphilic and polar peptides. (v) Neutral amphiphilic peptides permeabilize DOPC layers to ions to the greatest extent. (vi) The beta-sheet tape forming peptides are shown to be significantly less monolayer disruptive than antimicrobial peptides. These conclusions will greatly contribute to the rational design of new peptide-based biomaterials and biosensors.

  3. Angular distribution of products of ternary nuclear fission induced by cold polarized neutrons

    SciTech Connect

    Bunakov, V. E. Kadmensky, S. G. Kadmensky, S. S.

    2008-11-15

    Within quantum fission theory, angular distributions of products originating from the ternary fission of nuclei that is induced by polarized cold and thermal neutrons are investigated on the basis of a non-evaporative mechanism of third-particle emission and a consistent description of fission-channel coupling. It is shown that the inclusion of Coriolis interaction both in the region of the discrete and in the region of the continuous spectrum of states of the system undergoing fission leads to T-odd correlations in the aforementioned angular distributions. The properties of the TRI and ROT effects discovered recently, which are due to the interference between the fission amplitudes of neutron resonances, are explored. The results obtained here are compared with their counterparts from classic calculations based on the trajectory method.

  4. Up to 100% Improvement in Dynamic Nuclear Polarization Solid-State NMR Sensitivity Enhancement of Polymers by Removing Oxygen.

    PubMed

    Le, Dao; Ziarelli, Fabio; Phan, Trang N T; Mollica, Giulia; Thureau, Pierre; Aussenac, Fabien; Ouari, Olivier; Gigmes, Didier; Tordo, Paul; Viel, Stéphane

    2015-08-01

    High-field dynamic nuclear polarization (DNP) has emerged as a powerful technique for improving the sensitivity of solid-state NMR (SSNMR), yielding significant sensitivity enhancements for a variety of samples, including polymers. Overall, depending upon the type of polymer, the molecular weight, and the DNP sample preparation method, sensitivity enhancements between 5 and 40 have been reported. These promising enhancements remain, however, far from the theoretical maximum (>1000). Crucial to the success of DNP SSNMR is the DNP signal enhancement (εDNP ), which is the ratio of the NMR signal intensities with and without DNP. It is shown here that, for polymers exhibiting high affinity toward molecular oxygen (e.g., polystyrene), removing part of the absorbed (paramagnetic) oxygen from the solid-state samples available as powders (instead of dissolved or dispersed in a solvent) increases proton nuclear relaxation times and εDNP, hereby providing up to a two-fold sensitivity increase (i.e., a four-fold reduction in experimental time).

  5. Quantitation of a spin polarization-induced nuclear Overhauser effect (SPINOE) between a hyperpolarized 13C-labeled cell metabolite and water protons

    PubMed Central

    Marco-Rius, Irene; Bohndiek, Sarah E; Kettunen, Mikko I; Larkin, Timothy J; Basharat, Meer; Seeley, Colm; Brindle, Kevin M

    2014-01-01

    The spin polarization-induced nuclear Overhauser effect (SPINOE) describes the enhancement of spin polarization of solvent nuclei by the hyperpolarized spins of a solute. In this communication we demonstrate that SPINOEs can be observed between [1,4-13C2]fumarate, hyperpolarized using the dissolution dynamic nuclear polarization technique, and solvent water protons. We derive a theoretical expression for the expected enhancement and demonstrate that this fits well with experimental measurements. Although the magnitude of the effect is relatively small (around 2% measured here), the SPINOE increases at lower field strengths, so that at clinically relevant magnetic fields (1.5–3 T) it may be possible to track the passage through the circulation of a bolus containing a hyperpolarized 13C-labeled substrate through the increase in solvent water 1H signal. © 2014 The Authors. Contrast Media & Molecular Imaging published by John Wiley and Sons, Ltd. PMID:24523064

  6. Dynamic nuclear polarization and nuclear magnetic resonance in the vicinity of edge states of a 2DES in GaAs quantum wells.

    PubMed

    Bowers, Clifford R; Caldwell, Joshua D; Gusev, Guennadi; Kovalev, Alexey E; Olshanetsky, Eugene; Reno, John L; Simmons, Jerry A; Vitkalov, Sergey A

    2006-02-01

    Nuclear magnetic resonance is detected via the in-plane conductivity of a two-dimensional electron system at unity Landau level filling factor in the regime of the quantum Hall effect in narrow and wide quantum wells. The NMR is spatially selective to nuclei with a coupling to electrons in the current carrying edge states at the perimeter of the 2DES. Interpretation of the electron-nuclear double resonance signals is facilitated by numerical simulations. A new RF swept method for conductivity-detected NMR is introduced which offers more efficient signal averaging. The method is applied to the study of electric quadrupole interactions, weakly allowed overtone transitions, and evaluation of the extent of electron wave function delocalization in the wide quantum well.

  7. Required Assets for a Nuclear Energy Applied R&D Program

    SciTech Connect

    Harold F. McFarlane; Craig L. Jacobson

    2009-03-01

    This report is one of a set of three documents that have collectively identified and recommended research and development capabilities that will be required to advance nuclear energy in the next 20 to 50 years. The first report, Nuclear Energy for the Future: Required Research and Development Capabilities—An Industry Perspective, was produced by Battelle Memorial Institute at the request of the Assistant Secretary of Nuclear Energy. That report, drawn from input by industry, academia, and Department of Energy laboratories, can be found in Appendix 5.1. This Idaho National Laboratory report maps the nuclear-specific capabilities from the Battelle report onto facility requirements, identifying options from the set of national laboratory, university, industry, and international facilities. It also identifies significant gaps in the required facility capabilities. The third document, Executive Recommendations for Nuclear R&D Capabilities, is a letter report containing a set of recommendations made by a team of senior executives representing nuclear vendors, utilities, academia, and the national laboratories (at Battelle’s request). That third report can be found in Appendix 5.2. The three reports should be considered as set in order to have a more complete picture. The basis of this report was drawn from three sources: previous Department of Energy reports, workshops and committee meetings, and expert opinion. The facilities discussed were winnowed from several hundred facilities that had previously been catalogued and several additional facilities that had been overlooked in past exercises. The scope of this report is limited to commercial nuclear energy and those things the federal government, or more specifically the Office of Nuclear Energy, should do to support its expanded deployment in order to increase energy security and reduce carbon emissions. In the context of this report, capabilities mean innovative, well-structured research and development programs

  8. Defence sugarcane glycoproteins disorganize microtubules and prevent nuclear polarization and germination of Sporisorium scitamineum teliospores.

    PubMed

    Sánchez-Elordi, Elena; Baluška, František; Echevarría, Clara; Vicente, Carlos; Legaz, M Estrella

    2016-08-01

    Microtubules (MTs) are involved in the germination of Sporisorium scitamineum teliospores. Resistant varieties of sugar cane plants produce defence glycoproteins that prevent the infection of the plants by the filamentous fungi Sporisorium scitamineum. Here, we show that a fraction of these glycoproteins prevents the correct arrangement of MTs and causes nuclear fragmentation defects. As a result, nuclei cannot correctly migrate through the growing hyphae, causing germinative failure. Arginase activity contained in defence glycoproteins is already described for preventing fungal germination. Now, its enzymatically active form is presented as a link between the defensive capacity of glycoproteins and the MT disorganization in fungal cells. Active arginase is produced in healthy and resistant plants; conversely, it is not detected in the juice from susceptible varieties, which explains why MT depolarization, nuclear disorganization as well as germination of teliospores are not significantly affected by glycoproteins from non-resistant plants. Our results also suggest that susceptible plants try to increase their levels of arginase after detecting the presence of the pathogen. However, this signal comes "too late" and such defensive mechanism fails. PMID:27372179

  9. A combination of dynamic light scattering and polarized resonance Raman scattering applied in the study of Arenicola Marina extracellular hemoglobin.

    PubMed

    Jernshøj, K D; Hassing, S; Olsen, L F

    2013-08-14

    Arenicola Marina extracellular hemoglobin (Hbl Hb) is considered to be a promising candidate as a blood substitute. To entangle some of the properties of extracellular giant hexagonal bilayer hemoglobin (Hbl Hb) of Arenicola Marina, we combined polarized resonance Raman scattering (532 nm excitation) with dynamic light scattering (DLS) (632.8 nm). An analysis of the depolarization ratio of selected a(2g) skeletal modes of the heme in native Hbl Hb and porcine Hb, shows that the distortion of the heme group away from its ideal fourfold symmetry is much smaller for heme groups bound in the Hbl Hb than for heme groups bound in porcine Hb. Using DLS, the average hydrodynamic diameter () of Hbl Hb was measured at pH = 5, 7, 8, 9, and 10. At pH = 5 to 7, the Hbl Hb was found in its native form with equal to 24.2 nm, while at pH = 8 and 9, a dissociation process starts to take place resulting in = 9 nm. At pH = 10, only large aggregates of fragmented Hbl Hb with larger than 1000 nm was detected, however, a comparison of the DLS results with the polarized resonance Raman scattering (RRS) revealed that the coupling between the fragments did not involve direct interaction between the heme groups, but also that the local heme environment seems to be comparable in the aggregates and in the native Hbl Hb. By comparing the unpolarized RRS results obtained for erythrocytes (RBC) with those for Hbl Hb, led us to the important conclusion that Hbl Hb is much easier photolyzed than porcine RBC.

  10. Polarized optical spectroscopy applied to investigate two poly(phenylene-vinylene) polymers with different side chain structures

    NASA Astrophysics Data System (ADS)

    Pâlsson, Lars-Olof; Vaughan, Helen L.; Monkman, Andrew P.

    2006-10-01

    Two related poly(phenylene-vinylene) (PPV) light-emitting polymers have been investigated by means of polarized optical spectroscopy. The purpose of the investigation was to investigate the nature of the interactions in thin films and to examine what impact the difference in side chain structure and molecular weight in poly(2'-methoxy-5-2-ethyl-hexoxy)-1,4-phenylene vinylene (MEH-PPV) and poly(2-(3',7'-dimethyloctyloxy)-5-methoxy-1,4-phenylene-vinylene) (OC1C10-PPV) has on the electronic and optical properties of the two polymers. Aligning the polymers by dispersing them in anisotropic solvents and stretched films shows that the side chains have an impact on the relative orientations of the transition dipole moments. In anisotropic solvents the linear dichroism is larger for MEH-PPV than for the related polymer OC1C10-PPV, while in stretched films the opposite situation prevails. A lower polarization of the luminescence from OC1C10-PPV, relative to MEH-PPV, was also obtained independent of alignment medium used. The data therefore suggest that while mechanical stretching may align the OC1C10-PPV to a greater degree, the emitting species is distinct from the absorbing species. The circular dichroism (CD) spectra of both polymers undergo dramatic changes when the liquid phase and the solid state (film) are compared. The solution CD spectra shows no evidence of interchain interactions; instead the spectra of both systems indicate a helical conformation of the polymers. The CD spectra of films are dramatically different with the strong Cotton effect being observed. This points to the formation of an aggregate in the film, with an associated ground state interaction, an interchain species such as a physical dimer, or a more complex higher aggregate.

  11. A combination of dynamic light scattering and polarized resonance Raman scattering applied in the study of Arenicola Marina extracellular hemoglobin

    NASA Astrophysics Data System (ADS)

    Jernshøj, K. D.; Hassing, S.; Olsen, L. F.

    2013-08-01

    Arenicola Marina extracellular hemoglobin (Hbl Hb) is considered to be a promising candidate as a blood substitute. To entangle some of the properties of extracellular giant hexagonal bilayer hemoglobin (Hbl Hb) of Arenicola Marina, we combined polarized resonance Raman scattering (532 nm excitation) with dynamic light scattering (DLS) (632.8 nm). An analysis of the depolarization ratio of selected a2g skeletal modes of the heme in native Hbl Hb and porcine Hb, shows that the distortion of the heme group away from its ideal fourfold symmetry is much smaller for heme groups bound in the Hbl Hb than for heme groups bound in porcine Hb. Using DLS, the average hydrodynamic diameter (⟨dh⟩) of Hbl Hb was measured at pH = 5, 7, 8, 9, and 10. At pH = 5 to 7, the Hbl Hb was found in its native form with ⟨dh⟩ equal to 24.2 nm, while at pH = 8 and 9, a dissociation process starts to take place resulting in ⟨dh⟩ = 9 nm. At pH = 10, only large aggregates of fragmented Hbl Hb with ⟨dh⟩ larger than 1000 nm was detected, however, a comparison of the DLS results with the polarized resonance Raman scattering (RRS) revealed that the coupling between the fragments did not involve direct interaction between the heme groups, but also that the local heme environment seems to be comparable in the aggregates and in the native Hbl Hb. By comparing the unpolarized RRS results obtained for erythrocytes (RBC) with those for Hbl Hb, led us to the important conclusion that Hbl Hb is much easier photolyzed than porcine RBC.

  12. Palmer Quest: A Feasible Nuclear Fission "Vision Mission" to the Mars Polar Caps

    NASA Technical Reports Server (NTRS)

    Carsey, F. D.; Beegle, L. W.; Nakagawa, R.; Elliott, J. O.; Matthews, J. B.; Coleman, M. L.; Hecht, M. H.; Ivaniov, A. B.; Head, J. W.; Milkovich, S.

    2005-01-01

    We are engaged in a NASA Vision Mission study, called Palmer Quest after the American Antarctic explorer Nathaniel Palmer, to assess the presence of life and evaluate the habitability of the basal domain of the Mars polar caps. We address this goal through four objectives: 1. Determine the presence of amino acids, nutrients, and geochemical heterogeneity in the ice sheet. 2. Quantify and characterize the provenance of the amino acids in Mars ice. 3. Assess the stratification of outcropped units for indications of habitable zones. 4. Determine the accumulation of ice, mineralogic material, and amino acids in Mars ice caps over the present epoch. Because of the defined scientific goal for the vision mission, the Palmer Quest focus is astrobiological; however, the results of the study make us optimistic that aggressive multi-platform in-situ missions that address a wide range of objectives, such as climate change, can be supported by variations of the approach used on this mission. Mission Overview: The Palmer Quest baseline

  13. Technical Review of the Domestic Nuclear Detection Office Transformational and Applied Research Directorate’s Research and Development Program

    SciTech Connect

    Lavietes, Anthony; Trebes, James; Borchers, Robert; Dahlburg, Jill; Donnelly, John; Isles, Adam; Johnson, Neil; Knoll, Glenn; Kouzes, Richard T.; Lanza, Richard; Lieberman, Jodi; Lund, James; Prussin, Stanley G.; Russo, Jeanette; Slakey, Francis

    2013-01-01

    At the request of the Domestic Nuclear Detection Office (DNDO), a Review Committee comprised of representatives from the American Physical Society (APS) Panel on Public Affairs (POPA) and the Institute of Electrical and Electronics Engineers (IEEE) Nuclear and Plasma Sciences Society (NPSS) performed a technical review of the DNDO Transformational and Applied Research Directorate (TARD) research and development program. TARD’s principal objective is to address gaps in the Global Nuclear Detection Architecture (GNDA) through improvements in the performance, cost, and operational burden of detectors and systems. The charge to the Review Committee was to investigate the existing TARD research and development plan and portfolio, recommend changes to the existing plan, and recommend possible new R&D areas and opportunities. The Review Committee has several recommendations.

  14. Taming the SQUID: How a nuclear physics education (mostly) helped my career in applied physics

    NASA Astrophysics Data System (ADS)

    Espy, Michelle

    2013-10-01

    My degree is in experimental nuclear physics, specifically studying the interaction of pions with nuclei. But after graduation I accepted a post-doctoral research position with a team based on applications of the Superconducting Quantum Interference Device (SQUID) to the study of the human brain. Despite knowing nothing about the brain or SQUIDs to start with, I have gone on to enjoy a career in applications of the SQUID and other sensors to the detection of weak magnetic fields in a variety of problems from brain studies (magnetoencephalography) to ultra-low field nuclear magnetic resonance for detection of explosives and illicit material. In this talk I will present some background on SQUIDs and their application to the detection of ultra-weak magnetic fields of biological and non-biological origin. I will also provide a little insight into what it has been like to use a nuclear physics background to pursue other types of science.

  15. The Path to Sustainable Nuclear Energy. Basic and Applied Research Opportunities for Advanced Fuel Cycles

    SciTech Connect

    Finck, P.; Edelstein, N.; Allen, T.; Burns, C.; Chadwick, M.; Corradini, M.; Dixon, D.; Goff, M.; Laidler, J.; McCarthy, K.; Moyer, B.; Nash, K.; Navrotsky, A.; Oblozinsky, P.; Pasamehmetoglu, K.; Peterson, P.; Sackett, J.; Sickafus, K. E.; Tulenko, J.; Weber, W.; Morss, L.; Henry, G.

    2005-09-01

    The objective of this report is to identify new basic science that will be the foundation for advances in nuclear fuel-cycle technology in the near term, and for changing the nature of fuel cycles and of the nuclear energy industry in the long term. The goals are to enhance the development of nuclear energy, to maximize energy production in nuclear reactor parks, and to minimize radioactive wastes, other environmental impacts, and proliferation risks. The limitations of the once-through fuel cycle can be overcome by adopting a closed fuel cycle, in which the irradiated fuel is reprocessed and its components are separated into streams that are recycled into a reactor or disposed of in appropriate waste forms. The recycled fuel is irradiated in a reactor, where certain constituents are partially transmuted into heavier isotopes via neutron capture or into lighter isotopes via fission. Fast reactors are required to complete the transmutation of long-lived isotopes. Closed fuel cycles are encompassed by the Department of Energy?s Advanced Fuel Cycle Initiative (AFCI), to which basic scientific research can contribute. Two nuclear reactor system architectures can meet the AFCI objectives: a ?single-tier? system or a ?dual-tier? system. Both begin with light water reactors and incorporate fast reactors. The ?dual-tier? systems transmute some plutonium and neptunium in light water reactors and all remaining transuranic elements (TRUs) in a closed-cycle fast reactor. Basic science initiatives are needed in two broad areas: ? Near-term impacts that can enhance the development of either ?single-tier? or ?dual-tier? AFCI systems, primarily within the next 20 years, through basic research. Examples: Dissolution of spent fuel, separations of elements for TRU recycling and transmutation Design, synthesis, and testing of inert matrix nuclear fuels and non-oxide fuels Invention and development of accurate on-line monitoring systems for chemical and nuclear species in the nuclear

  16. Dual functions for the Schizosaccharomyces pombe inositol kinase Ipk1 in nuclear mRNA export and polarized cell growth.

    PubMed

    Sarmah, Bhaskarjyoti; Wente, Susan R

    2009-02-01

    The inositol 1,3,4,5,6-pentakisphosphate (IP(5)) 2-kinase (Ipk1) catalyzes the production of inositol hexakisphosphate (IP(6)) in eukaryotic cells. Previous studies have shown that IP(6) is required for efficient nuclear mRNA export in the budding yeast Saccharomyces cerevisiae. Here, we report the first functional analysis of ipk1(+) in Schizosaccharomyces pombe. S. pombe Ipk1 (SpIpk1) is unique among Ipk1 orthologues in that it harbors a novel amino (N)-terminal domain with coiled-coil structural motifs similar to those of BAR (Bin-amphiphysin-Rvs) domain proteins. Mutants with ipk1(+) deleted (ipk1Delta) had mRNA export defects as well as pleiotropic defects in polarized growth, cell morphology, endocytosis, and cell separation. The SpIpk1 catalytic carboxy-terminal domain was required to rescue these defects, and the mRNA export block was genetically linked to SpDbp5 function and, likely, IP(6) production. However, the overexpression of the N-terminal domain alone also inhibited these functions in wild-type cells. This revealed a distinct noncatalytic function for the N-terminal domain. To test for connections with other inositol polyphosphates, we also analyzed whether the loss of asp1(+) function, encoding an IP(6) kinase downstream of Ipk1, had an effect on ipk1Delta cells. The asp1Delta mutant alone did not block mRNA export, and its cell morphology, polarized growth, and endocytosis defects were less severe than those of ipk1Delta cells. Moreover, ipk1Delta asp1Delta double mutants had altered inositol polyphosphate levels distinct from those of the ipk1Delta mutant. This suggested novel roles for asp1(+) upstream of ipk1(+). We propose that IP(6) production is a key signaling linchpin for regulating multiple essential cellular processes. PMID:19047361

  17. Induced polarization imaging applied to exploration for low-sulfidation epithermal Au-Ag deposits, Seongsan mineralized district, South Korea

    NASA Astrophysics Data System (ADS)

    Han, Man-Ho; Shin, Seung Wook; Park, Samgyu; Cho, Seong-Jun; Kim, Jung-Ho

    2016-10-01

    The determination of mineralization boundaries during mineral exploration for undiscovered low-sulfidation epithermal Au-Ag deposits is a significant challenge because of the extensive survey areas required. Induced polarization (IP) imaging is an effective geophysical technique for the detection of sulfides or clay. Thus, this method is considered useful to determine the boundaries of subsurface mineralization and hydrothermal alteration associated with epithermal deposits. We used 2D and 3D IP imaging to define the silicification and mineralization boundaries of the Moisan deposit in the Seongsan mineralized district, which is geologically well-known. The boundaries of the silicification zone were defined by high resistivity values of 600 Ω-m, and those of the mineralization zone were defined by high global chargeability values of 3 mV V-1. The continuity of the high resistivity anomaly corresponded well to the silicification (quartz veins) exposed in outcrop. In addition, it is geologically reasonable that the chargeability anomaly, ⩾3 mV V-1, associated with the mineralization/hydrothermal alteration zone was concentrated at near-surface depths, and extensively surrounding the resistivity anomaly, ⩾600 Ω-m, associated with the silicification zone.

  18. Instabilities in fissioning plasmas as applied to the gas-core nuclear rocket-engine

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The compressional wave spectrum excited in a fissioning uranium plasma confined in a cavity such as a gas cored nuclear reactor, is studied. Computer results are presented that solve the fluid equations for this problem including the effects of spatial gradients, nonlinearities, and neutron density gradients in the reactor. Typically the asymptotic fluctuation level for the plasma pressure is of order 1 percent.

  19. ON THE ANODIC POLARIZATION BEHAVIOR OF CARBON STEEL IN HANFORD NUCLEAR WASTES

    SciTech Connect

    BOOMER, K.D.

    2007-01-31

    The effect of the important chemical constituents in the Hanford nuclear waste simulant on the anodic behavior of carbon steel was studied. Specifically, the effect of pH, nitrite concentration, nitrite/nitrate concentration ratios, total organic carbon and the chloride concentration on the open circuit potential, pitting potential and repassivation potential was evaluated. It was found that pH adjusting, although capable of returning the tank chemistry back to specification, did not significantly reduce the corrosivity of the stimulant compared to the present condition. Nitrite was found to be a potent inhibitor for carbon steel. A critical concentration of approximately 1.2M appeared to be beneficial to increase the difference of repassivation potential and open circuit potential considerably and thus prevent pitting corrosion from occurring. No further benefit was gained when increasing nitrite concentration to a higher level. The organic compounds were found to be weak inhibitors in the absence of nitrite and the change of chloride from 0.05M to 0.2M did not alter the anodic behavior dramatically.

  20. A peripheral component interconnect express-based scalable and highly integrated pulsed spectrometer for solution state dynamic nuclear polarization

    SciTech Connect

    He, Yugui; Liu, Chaoyang; Feng, Jiwen; Wang, Dong; Chen, Fang; Liu, Maili; Zhang, Zhi; Wang, Chao

    2015-08-15

    High sensitivity, high data rates, fast pulses, and accurate synchronization all represent challenges for modern nuclear magnetic resonance spectrometers, which make any expansion or adaptation of these devices to new techniques and experiments difficult. Here, we present a Peripheral Component Interconnect Express (PCIe)-based highly integrated distributed digital architecture pulsed spectrometer that is implemented with electron and nucleus double resonances and is scalable specifically for broad dynamic nuclear polarization (DNP) enhancement applications, including DNP-magnetic resonance spectroscopy/imaging (DNP-MRS/MRI). The distributed modularized architecture can implement more transceiver channels flexibly to meet a variety of MRS/MRI instrumentation needs. The proposed PCIe bus with high data rates can significantly improve data transmission efficiency and communication reliability and allow precise control of pulse sequences. An external high speed double data rate memory chip is used to store acquired data and pulse sequence elements, which greatly accelerates the execution of the pulse sequence, reduces the TR (time of repetition) interval, and improves the accuracy of TR in imaging sequences. Using clock phase-shift technology, we can produce digital pulses accurately with high timing resolution of 1 ns and narrow widths of 4 ns to control the microwave pulses required by pulsed DNP and ensure overall system synchronization. The proposed spectrometer is proved to be both feasible and reliable by observation of a maximum signal enhancement factor of approximately −170 for {sup 1}H, and a high quality water image was successfully obtained by DNP-enhanced spin-echo {sup 1}H MRI at 0.35 T.

  1. A peripheral component interconnect express-based scalable and highly integrated pulsed spectrometer for solution state dynamic nuclear polarization.

    PubMed

    He, Yugui; Feng, Jiwen; Zhang, Zhi; Wang, Chao; Wang, Dong; Chen, Fang; Liu, Maili; Liu, Chaoyang

    2015-08-01

    High sensitivity, high data rates, fast pulses, and accurate synchronization all represent challenges for modern nuclear magnetic resonance spectrometers, which make any expansion or adaptation of these devices to new techniques and experiments difficult. Here, we present a Peripheral Component Interconnect Express (PCIe)-based highly integrated distributed digital architecture pulsed spectrometer that is implemented with electron and nucleus double resonances and is scalable specifically for broad dynamic nuclear polarization (DNP) enhancement applications, including DNP-magnetic resonance spectroscopy/imaging (DNP-MRS/MRI). The distributed modularized architecture can implement more transceiver channels flexibly to meet a variety of MRS/MRI instrumentation needs. The proposed PCIe bus with high data rates can significantly improve data transmission efficiency and communication reliability and allow precise control of pulse sequences. An external high speed double data rate memory chip is used to store acquired data and pulse sequence elements, which greatly accelerates the execution of the pulse sequence, reduces the TR (time of repetition) interval, and improves the accuracy of TR in imaging sequences. Using clock phase-shift technology, we can produce digital pulses accurately with high timing resolution of 1 ns and narrow widths of 4 ns to control the microwave pulses required by pulsed DNP and ensure overall system synchronization. The proposed spectrometer is proved to be both feasible and reliable by observation of a maximum signal enhancement factor of approximately -170 for (1)H, and a high quality water image was successfully obtained by DNP-enhanced spin-echo (1)H MRI at 0.35 T. PMID:26329168

  2. A peripheral component interconnect express-based scalable and highly integrated pulsed spectrometer for solution state dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    He, Yugui; Feng, Jiwen; Zhang, Zhi; Wang, Chao; Wang, Dong; Chen, Fang; Liu, Maili; Liu, Chaoyang

    2015-08-01

    High sensitivity, high data rates, fast pulses, and accurate synchronization all represent challenges for modern nuclear magnetic resonance spectrometers, which make any expansion or adaptation of these devices to new techniques and experiments difficult. Here, we present a Peripheral Component Interconnect Express (PCIe)-based highly integrated distributed digital architecture pulsed spectrometer that is implemented with electron and nucleus double resonances and is scalable specifically for broad dynamic nuclear polarization (DNP) enhancement applications, including DNP-magnetic resonance spectroscopy/imaging (DNP-MRS/MRI). The distributed modularized architecture can implement more transceiver channels flexibly to meet a variety of MRS/MRI instrumentation needs. The proposed PCIe bus with high data rates can significantly improve data transmission efficiency and communication reliability and allow precise control of pulse sequences. An external high speed double data rate memory chip is used to store acquired data and pulse sequence elements, which greatly accelerates the execution of the pulse sequence, reduces the TR (time of repetition) interval, and improves the accuracy of TR in imaging sequences. Using clock phase-shift technology, we can produce digital pulses accurately with high timing resolution of 1 ns and narrow widths of 4 ns to control the microwave pulses required by pulsed DNP and ensure overall system synchronization. The proposed spectrometer is proved to be both feasible and reliable by observation of a maximum signal enhancement factor of approximately -170 for 1H, and a high quality water image was successfully obtained by DNP-enhanced spin-echo 1H MRI at 0.35 T.

  3. Dynamic Nuclear Polarization enhanced NMR at 187 GHz/284 MHz using an Extended Interaction Klystron amplifier.

    PubMed

    Kemp, Thomas F; Dannatt, Hugh R W; Barrow, Nathan S; Watts, Anthony; Brown, Steven P; Newton, Mark E; Dupree, Ray

    2016-04-01

    A Dynamic Nuclear Polarisation (DNP) enhanced solid-state Magic Angle Spinning (MAS) NMR spectrometer which uses a 187 GHz (corresponding to (1)H NMR frequency of 284 MHz) Extended Interaction Klystron (EIK) amplifier as the microwave source is briefly described. Its performance is demonstrated for a biomolecule (bacteriorhodopsin), a pharmaceutical, and surface functionalised silica. The EIK is very compact and easily incorporated into an existing spectrometer. The bandwidth of the amplifier is sufficient that it obviates the need for a sweepable magnetic field, once set, for all commonly used radicals. The variable power (CW or pulsed) output from the EIK is transmitted to the DNP-NMR probe using a quasi-optic system with a high power isolator and a corrugated waveguide which feeds the microwaves into the DNP-NMR probe. Curved mirrors inside the probe project the microwaves down the axis of the MAS rotor, giving a very efficient system such that maximum DNP enhancement is achieved with less than 3 W output from the microwave source. The DNP-NMR probe operates with a sample temperature down to 90K whilst spinning at 8 kHz. Significant enhancements, in excess of 100 for bacteriorhodopsin in purple membrane (bR in PM), are shown along with spectra which are enhanced by ≈25 with respect to room temperature, for both the pharmaceutical furosemide and surface functionalised silica. These enhancements allow hitherto prohibitively time consuming experiments to be undertaken. The power at which the DNP enhancement in bR in PM saturates does not change significantly between 90K and 170 K even though the enhancement drops by a factor of ≈11. As the DNP build up time decreases by a factor 3 over this temperature range, the reduction in T1n is presumably a significant contribution to the drop in enhancement. PMID:26867091

  4. Dynamic Nuclear Polarization enhanced NMR at 187 GHz/284 MHz using an Extended Interaction Klystron amplifier.

    PubMed

    Kemp, Thomas F; Dannatt, Hugh R W; Barrow, Nathan S; Watts, Anthony; Brown, Steven P; Newton, Mark E; Dupree, Ray

    2016-04-01

    A Dynamic Nuclear Polarisation (DNP) enhanced solid-state Magic Angle Spinning (MAS) NMR spectrometer which uses a 187 GHz (corresponding to (1)H NMR frequency of 284 MHz) Extended Interaction Klystron (EIK) amplifier as the microwave source is briefly described. Its performance is demonstrated for a biomolecule (bacteriorhodopsin), a pharmaceutical, and surface functionalised silica. The EIK is very compact and easily incorporated into an existing spectrometer. The bandwidth of the amplifier is sufficient that it obviates the need for a sweepable magnetic field, once set, for all commonly used radicals. The variable power (CW or pulsed) output from the EIK is transmitted to the DNP-NMR probe using a quasi-optic system with a high power isolator and a corrugated waveguide which feeds the microwaves into the DNP-NMR probe. Curved mirrors inside the probe project the microwaves down the axis of the MAS rotor, giving a very efficient system such that maximum DNP enhancement is achieved with less than 3 W output from the microwave source. The DNP-NMR probe operates with a sample temperature down to 90K whilst spinning at 8 kHz. Significant enhancements, in excess of 100 for bacteriorhodopsin in purple membrane (bR in PM), are shown along with spectra which are enhanced by ≈25 with respect to room temperature, for both the pharmaceutical furosemide and surface functionalised silica. These enhancements allow hitherto prohibitively time consuming experiments to be undertaken. The power at which the DNP enhancement in bR in PM saturates does not change significantly between 90K and 170 K even though the enhancement drops by a factor of ≈11. As the DNP build up time decreases by a factor 3 over this temperature range, the reduction in T1n is presumably a significant contribution to the drop in enhancement.

  5. Simultaneous and spectroscopic redox molecular imaging of multiple free radical intermediates using dynamic nuclear polarization-magnetic resonance imaging.

    PubMed

    Hyodo, Fuminori; Ito, Shinji; Yasukawa, Keiji; Kobayashi, Ryoma; Utsumi, Hideo

    2014-08-01

    Redox reactions that generate free radical intermediates are essential to metabolic processes. However, their intermediates can produce reactive oxygen species, which may promote diseases related to oxidative stress. We report here the use of dynamic nuclear polarization-magnetic resonance imaging (DNP-MRI) to conduct redox molecular imaging. Using DNP-MRI, we obtained simultaneous images of free radical intermediates generated from the coenzyme Q10 (CoQ10), flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD) involved in the mitochondrial electron transport chain as well as the radicals derived from vitamins E and K1. Each of these free radicals was imaged in real time in a phantom comprising a mixture of free radicals localized in either lipophilic or aqueous environments. Changing the frequency of electron spin resonance (ESR) irradiation also allowed each of the radical species to be distinguished in the spectroscopic images. This study is the first to report the spectroscopic DNP-MRI imaging of free radical intermediates that are derived from endogenous species involved in metabolic processes.

  6. Optimization of dynamic nuclear polarization experiments in aqueous solution at 15 MHz/9.7 GHz: a comparative study with DNP at 140 MHz/94 GHz.

    PubMed

    Türke, Maria-Teresa; Tkach, Igor; Reese, Marcel; Höfer, Peter; Bennati, Marina

    2010-06-14

    Dynamic nuclear polarization is emerging as a potential tool to increase the sensitivity of NMR aiming at the detection of macromolecules in liquid solution. One possibility for such an experimental design is to perform the polarization step between electrons and nuclei at low magnetic fields and then transfer the sample to a higher field for NMR detection. In this case, an independent optimization of the polarizer and detection set ups is required. In the present paper we describe the optimization of a polarizer set up at 15 MHz (1)H NMR/9.7 GHz EPR frequencies based on commercial hardware. The sample consists of the nitroxide radical TEMPONE-D,(15)N in water, for which the dimensions were systematically decreased to fit the homogeneous B(1) region of a dielectric ENDOR resonator. With an available B(1) microwave field up to 13 G we observe a maximum DNP enhancement of -170 at room temperature by irradiating on either one of the EPR lines. The DNP enhancement was saturated at all polarizer concentrations. Pulsed ELDOR experiments revealed that the saturation level of the two hyperfine lines is such that the DNP enhancements are well consistent with the coupling factors derived from NMRD data. By raising the polarizing field and frequencies 10-fold, i.e. to 140 MHz (1)H/94 GHz EPR, we reach an enhancement of -43 at microwave field strengths (B(1) approximately 5 G). The results are discussed in view of an application for a DNP spectrometer.

  7. Applying Human Factors Evaluation and Design Guidance to a Nuclear Power Plant Digital Control System

    SciTech Connect

    Thomas Ulrich; Ronald Boring; William Phoenix; Emily Dehority; Tim Whiting; Jonathan Morrell; Rhett Backstrom

    2012-08-01

    The United States (U.S.) nuclear industry, like similar process control industries, has moved toward upgrading its control rooms. The upgraded control rooms typically feature digital control system (DCS) displays embedded in the panels. These displays gather information from the system and represent that information on a single display surface. In this manner, the DCS combines many previously separate analog indicators and controls into a single digital display, whereby the operators can toggle between multiple windows to monitor and control different aspects of the plant. The design of the DCS depends on the function of the system it monitors, but revolves around presenting the information most germane to an operator at any point in time. DCSs require a carefully designed human system interface. This report centers on redesigning existing DCS displays for an example chemical volume control system (CVCS) at a U.S. nuclear power plant. The crucial nature of the CVCS, which controls coolant levels and boration in the primary system, requires a thorough human factors evaluation of its supporting DCS. The initial digital controls being developed for the DCSs tend to directly mimic the former analog controls. There are, however, unique operator interactions with a digital vs. analog interface, and the differences have not always been carefully factored in the translation of an analog interface to a replacement DCS. To ensure safety, efficiency, and usability of the emerging DCSs, a human factors usability evaluation was conducted on a CVCS DCS currently being used and refined at an existing U.S. nuclear power plant. Subject matter experts from process control engineering, software development, and human factors evaluated the DCS displays to document potential usability issues and propose design recommendations. The evaluation yielded 167 potential usability issues with the DCS. These issues should not be considered operator performance problems but rather opportunities

  8. Applying radiological emergency planning experience to hazardous materials emergency planning within the nuclear industry

    SciTech Connect

    Foltman, A.; Newsom, D.; Lerner, K.

    1988-01-01

    The nuclear industry has extensive radiological emergency planning (REP) experience that is directly applicable to hazardous materials emergency planning. Recently, the Feed Materials Production Center near Cincinnati, Ohio, successfully demonstrated such application. The REP experience includes conceptual bases and standards for developing plans that have been tested in hundreds of full-scale exercises. The exercise program itself is also well developed. Systematic consideration of the differences between chemical and radiological hazards shows that relatively minor changes to the REP bases and standards are necessary. Conduct of full-scale, REP-type exercises serves to test the plans, provide training, and engender confidence and credibility.

  9. Construction and 13C NMR signal-amplification efficiency of a dynamic nuclear polarizer at 6.4 T and 1.4 K

    NASA Astrophysics Data System (ADS)

    Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Ferguson, Sarah; Taylor, David; McDonald, George; Lumata, Lloyd

    Dissolution dynamic nuclear polarization (DNP) is a rapidly emerging technique in biomedical and metabolic imaging since it amplifies the liquid-state nuclear magnetic resonance (NMR) and imaging (MRI) signals by >10,000-fold. Originally used in nuclear scattering experiments, DNP works by creating a non-Boltzmann nuclear spin distribution by transferring the high electron (γ = 28,000 MHz/T) thermal polarization to the nuclear spins via microwave irradiation of the sample at high magnetic field and low temperature. A dissolution device is used to rapidly dissolve the frozen sample and consequently produces an injectable ``hyperpolarized'' liquid at physiologically-tolerable temperature. Here we report the construction and performance evaluation of a dissolution DNP hyperpolarizer at 6.4 T and 1.4 K using a continuous-flow cryostat. The solid and liquid-state 13C NMR signal enhancement levels of 13C acetate samples doped with trityl OX063 and 4-oxo-TEMPO free radicals will be discussed and compared with the results from the 3.35 T commercial hyperpolarizer. This work is supported by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  10. Applied nuclear data research and development. Progress report, January 1-March 31, 1981

    SciTech Connect

    Baxman, C.I.; Young, P.G.

    1981-07-01

    Activities of the Los Alamos Nuclear Data Group for January 1 through March 31, 1981, are described. Topics include: (1) peripheral effects in R-matrix theory; (2) Coulomb corrections in light nuclei; (3) new R-matrix analysis of reactions in the /sup 7/Li system; (4) variance-covariance analysis of n + Li reactions; (5) calculated charged-particle emission in the mass-90 region; (6) determination of deformed optical model parameters for neutron reactions on /sup 235/U and /sup 239/Pu; (7) calculation of excited state cross sections for actinide nuclei; (8) calculation of the prompt neutron spectrum and ..nu../sub p/ for the spontaneous fission of /sup 252/Cf; (9) international nuclear model codes comparison study; (10) an improved calculation of heating and radiation damage from neutron capture; (11) LMFBR cross-section production with MAX; (12) TRANSX development; (13) THOR calculations; (14) covariance processing; (15) analysis of charges for use of central computing facility; (16) S/sub n/ calculations for D/sub 2/O sphere; (17) integral data testing of ENDF/B fission-product data; (18) decay power comparisons using ENDF/B-IV and -V data in CINDER-10; (19) ENDF/B-V data testing and summary data; (20) SPEC5: code to produce multigroup spectra; and (21) calculation of H. B. Robinson-2 fuel isotopics and comparison with measurements. (WHK)

  11. Medical Image Processing Server applied to Quality Control of Nuclear Medicine.

    NASA Astrophysics Data System (ADS)

    Vergara, C.; Graffigna, J. P.; Marino, E.; Omati, S.; Holleywell, P.

    2016-04-01

    This paper is framed within the area of medical image processing and aims to present the process of installation, configuration and implementation of a processing server of medical images (MIPS) in the Fundación Escuela de Medicina Nuclear located in Mendoza, Argentina (FUESMEN). It has been developed in the Gabinete de Tecnologia Médica (GA.TE.ME), Facultad de Ingeniería-Universidad Nacional de San Juan. MIPS is a software that using the DICOM standard, can receive medical imaging studies of different modalities or viewing stations, then it executes algorithms and finally returns the results to other devices. To achieve the objectives previously mentioned, preliminary tests were conducted in the laboratory. More over, tools were remotely installed in clinical enviroment. The appropiate protocols for setting up and using them in different services were established once defined those suitable algorithms. Finally, it’s important to focus on the implementation and training that is provided in FUESMEN, using nuclear medicine quality control processes. Results on implementation are exposed in this work.

  12. A versatile and modular quasi optics-based 200GHz dual dynamic nuclear polarization and electron paramagnetic resonance instrument.

    PubMed

    Siaw, Ting Ann; Leavesley, Alisa; Lund, Alicia; Kaminker, Ilia; Han, Songi

    2016-03-01

    Solid-state dynamic nuclear polarization (DNP) at higher magnetic fields (>3T) and cryogenic temperatures (∼ 2-90K) has gained enormous interest and seen major technological advances as an NMR signal enhancing technique. Still, the current state of the art DNP operation is not at a state at which sample and freezing conditions can be rationally chosen and the DNP performance predicted a priori, but relies on purely empirical approaches. An important step towards rational optimization of DNP conditions is to have access to DNP instrumental capabilities to diagnose DNP performance and elucidate DNP mechanisms. The desired diagnoses include the measurement of the "DNP power curve", i.e. the microwave (MW) power dependence of DNP enhancement, the "DNP spectrum", i.e. the MW frequency dependence of DNP enhancement, the electron paramagnetic resonance (EPR) spectrum, and the saturation and spectral diffusion properties of the EPR spectrum upon prolonged MW irradiation typical of continuous wave (CW) DNP, as well as various electron and nuclear spin relaxation parameters. Even basic measurements of these DNP parameters require versatile instrumentation at high magnetic fields not commercially available to date. In this article, we describe the detailed design of such a DNP instrument, powered by a solid-state MW source that is tunable between 193 and 201 GHz and outputs up to 140 mW of MW power. The quality and pathway of the transmitted and reflected MWs is controlled by a quasi-optics (QO) bridge and a corrugated waveguide, where the latter couples the MW from an open-space QO bridge to the sample located inside the superconducting magnet and vice versa. Crucially, the versatility of the solid-state MW source enables the automated acquisition of frequency swept DNP spectra, DNP power curves, the diagnosis of MW power and transmission, and frequency swept continuous wave (CW) and pulsed EPR experiments. The flexibility of the DNP instrument centered around the QO MW

  13. A versatile and modular quasi optics-based 200GHz dual dynamic nuclear polarization and electron paramagnetic resonance instrument.

    PubMed

    Siaw, Ting Ann; Leavesley, Alisa; Lund, Alicia; Kaminker, Ilia; Han, Songi

    2016-03-01

    Solid-state dynamic nuclear polarization (DNP) at higher magnetic fields (>3T) and cryogenic temperatures (∼ 2-90K) has gained enormous interest and seen major technological advances as an NMR signal enhancing technique. Still, the current state of the art DNP operation is not at a state at which sample and freezing conditions can be rationally chosen and the DNP performance predicted a priori, but relies on purely empirical approaches. An important step towards rational optimization of DNP conditions is to have access to DNP instrumental capabilities to diagnose DNP performance and elucidate DNP mechanisms. The desired diagnoses include the measurement of the "DNP power curve", i.e. the microwave (MW) power dependence of DNP enhancement, the "DNP spectrum", i.e. the MW frequency dependence of DNP enhancement, the electron paramagnetic resonance (EPR) spectrum, and the saturation and spectral diffusion properties of the EPR spectrum upon prolonged MW irradiation typical of continuous wave (CW) DNP, as well as various electron and nuclear spin relaxation parameters. Even basic measurements of these DNP parameters require versatile instrumentation at high magnetic fields not commercially available to date. In this article, we describe the detailed design of such a DNP instrument, powered by a solid-state MW source that is tunable between 193 and 201 GHz and outputs up to 140 mW of MW power. The quality and pathway of the transmitted and reflected MWs is controlled by a quasi-optics (QO) bridge and a corrugated waveguide, where the latter couples the MW from an open-space QO bridge to the sample located inside the superconducting magnet and vice versa. Crucially, the versatility of the solid-state MW source enables the automated acquisition of frequency swept DNP spectra, DNP power curves, the diagnosis of MW power and transmission, and frequency swept continuous wave (CW) and pulsed EPR experiments. The flexibility of the DNP instrument centered around the QO MW

  14. A versatile and modular quasi optics-based 200 GHz dual dynamic nuclear polarization and electron paramagnetic resonance instrument

    NASA Astrophysics Data System (ADS)

    Siaw, Ting Ann; Leavesley, Alisa; Lund, Alicia; Kaminker, Ilia; Han, Songi

    2016-03-01

    Solid-state dynamic nuclear polarization (DNP) at higher magnetic fields (>3 T) and cryogenic temperatures (∼2-90 K) has gained enormous interest and seen major technological advances as an NMR signal enhancing technique. Still, the current state of the art DNP operation is not at a state at which sample and freezing conditions can be rationally chosen and the DNP performance predicted a priori, but relies on purely empirical approaches. An important step towards rational optimization of DNP conditions is to have access to DNP instrumental capabilities to diagnose DNP performance and elucidate DNP mechanisms. The desired diagnoses include the measurement of the "DNP power curve", i.e. the microwave (MW) power dependence of DNP enhancement, the "DNP spectrum", i.e. the MW frequency dependence of DNP enhancement, the electron paramagnetic resonance (EPR) spectrum, and the saturation and spectral diffusion properties of the EPR spectrum upon prolonged MW irradiation typical of continuous wave (CW) DNP, as well as various electron and nuclear spin relaxation parameters. Even basic measurements of these DNP parameters require versatile instrumentation at high magnetic fields not commercially available to date. In this article, we describe the detailed design of such a DNP instrument, powered by a solid-state MW source that is tunable between 193 and 201 GHz and outputs up to 140 mW of MW power. The quality and pathway of the transmitted and reflected MWs is controlled by a quasi-optics (QO) bridge and a corrugated waveguide, where the latter couples the MW from an open-space QO bridge to the sample located inside the superconducting magnet and vice versa. Crucially, the versatility of the solid-state MW source enables the automated acquisition of frequency swept DNP spectra, DNP power curves, the diagnosis of MW power and transmission, and frequency swept continuous wave (CW) and pulsed EPR experiments. The flexibility of the DNP instrument centered around the QO MW

  15. 10 CFR Appendix E to Part 73 - Levels of Physical Protection To Be Applied in International Transport of Nuclear Material 1

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 2 2014-01-01 2014-01-01 false Levels of Physical Protection To Be Applied in International Transport of Nuclear Material 1 E Appendix E to Part 73 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PHYSICAL PROTECTION OF PLANTS AND MATERIALS Pt. 73, App. E Appendix E to Part 73—Levels...

  16. 10 CFR Appendix E to Part 73 - Levels of Physical Protection To Be Applied in International Transport of Nuclear Material 1

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 2 2012-01-01 2012-01-01 false Levels of Physical Protection To Be Applied in International Transport of Nuclear Material 1 E Appendix E to Part 73 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PHYSICAL PROTECTION OF PLANTS AND MATERIALS Pt. 73, App. E Appendix E to Part 73—Levels...

  17. 10 CFR Appendix E to Part 73 - Levels of Physical Protection To Be Applied in International Transport of Nuclear Material 1

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 2 2011-01-01 2011-01-01 false Levels of Physical Protection To Be Applied in International Transport of Nuclear Material 1 E Appendix E to Part 73 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PHYSICAL PROTECTION OF PLANTS AND MATERIALS Pt. 73, App. E Appendix E to Part 73—Levels...

  18. 10 CFR Appendix E to Part 73 - Levels of Physical Protection To Be Applied in International Transport of Nuclear Material 1

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 2 2013-01-01 2013-01-01 false Levels of Physical Protection To Be Applied in International Transport of Nuclear Material 1 E Appendix E to Part 73 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PHYSICAL PROTECTION OF PLANTS AND MATERIALS Pt. 73, App. E Appendix E to Part 73—Levels...

  19. 10 CFR Appendix E to Part 73 - Levels of Physical Protection To Be Applied in International Transport of Nuclear Material 1

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Levels of Physical Protection To Be Applied in International Transport of Nuclear Material 1 E Appendix E to Part 73 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PHYSICAL PROTECTION OF PLANTS AND MATERIALS Pt. 73, App. E Appendix E to Part 73—Levels...

  20. Monitoring of the Polar Stratospheric Clouds formation and evolution in Antarctica in August 2007 during IPY with the MATCH method applied to lidar data

    NASA Astrophysics Data System (ADS)

    Montoux, Nadege; David, Christine; Klekociuk, Andrew; Pitts, Michael; di Liberto, Luca; Snels, Marcel; Jumelet, Julien; Bekki, Slimane; Larsen, Niels

    2010-05-01

    The project ORACLE-O3 ("Ozone layer and UV RAdiation in a changing CLimate Evaluated during IPY") is one of the coordinated international proposals selected for the International Polar Year (IPY). As part of this global project, LOLITA-PSC ("Lagrangian Observations with Lidar Investigations and Trajectories in Antarctica and Arctic, of PSC") is devoted to Polar Stratospheric Clouds (PSC) studies. Indeed, understanding the formation and evolution of PSC is an important issue to quantify the impact of climate changes on their frequency of formation and, further, on chlorine activation and subsequent ozone depletion. In this framework, three lidar stations performed PSC observations in Antarctica during the 2006, 2007, and 2008 winters: Davis (68.58°S, 77.97°E), McMurdo (77.86°S, 166.48°E) and Dumont D'Urville (66.67°S, 140.01°E). The data are completed with the lidar data from CALIOP ("Cloud-Aerosol Lidar with Orthogonal Polarization") onboard the CALIPSO ("Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation") satellite. Lagrangian trajectory calculations are used to identify air masses with PSCs sounded by several ground-based lidar stations with the same method, called MATCH, applied for the first time in Arctic to study the ozone depletion with radiosoundings. The evolution of the optical properties of the PSCs and thus the type of PSCs formed (supercooled ternary solution, nitric acid trihydrate particles or ice particles) could thus be linked to the thermodynamical evolution of the air mass deduced from the trajectories. A modeling with the microphysical model of the Danish Meteorological Institute allows assessing our ability to predict PSCs for various environmental conditions. Indeed, from pressure and temperature evolution, the model allows retrieving the types of particles formed as well as their mean radii, their concentrations and could also simulate the lidar signals. In a first step, a case in August 2007 around 17-18 km, involving

  1. U(5)-SU(3) nuclear shape transition within the interacting boson model applied to dysprosium isotopes

    NASA Astrophysics Data System (ADS)

    Kotb, M.

    2016-07-01

    In the framework of the interacting boson model (IBM) with intrinsic coherent state, the shape Hamiltonian from spherical vibrator U(5) to axially symmetric prolate deformed rotator SU(3) are examined. The Hamiltonian used is composed of a single boson energy term and quadrupole term. The potential energy surfaces (PES' s) corresponding to the U(5)-SU(3) transition are calculated with variation of a scaling and control parameters. The model is applied to 150-162Dy chain of isotopes. In this chain a change from spherical to well deformed nuclei is observed when moving from the lighter to heavier isotopes. 156Dy is a good candidate for the critical point symmetry X(5). The parameters of the model are determined by using a computer simulated search program in order to minimize the deviation between our calculated and some selected experimental energy levels, B(E2) transition rates and the two neutron separation energies S2n. We have also studied the energy ratios and the B(E2) values for the yrast state of the critical nucleus. The nucleon pair transfer intensities between ground-ground and ground-beta states are examined within IBM and boson intrinsic coherent framework.

  2. Dynamic nuclear polarization properties of nitroxyl radical in high viscous liquid using Overhauser-enhanced Magnetic Resonance Imaging (OMRI).

    PubMed

    Kumara Dhas, M; Utsumi, Hideo; Jawahar, A; Milton Franklin Benial, A

    2015-08-01

    The dynamic nuclear polarization (DNP) studies were carried out for (15)N labeled carbamoyl-PROXYL in pure water and pure water/glycerol mixtures of different viscosities (1.8cP, 7cP and 14cP). The dependence of DNP parameters was demonstrated over a range of agent concentration, viscosities, RF power levels and ESR irradiation time. DNP spectra were also recorded for 2mM concentration of (15)N labeled carbamoyl-PROXYL in pure water and pure water/glycerol mixtures of different viscosities. The DNP factors were measured as a function of ESR irradiation time, which increases linearly up to 2mM agent concentration in pure water and pure water/glycerol mixtures of different viscosities. The DNP factor started declining in the higher concentration region (∼3mM), which is due to the ESR line width broadening. The water proton spin-lattice relaxation time was measured at very low Zeeman field (14.529mT). The increased DNP factor (35%) was observed for solvent 2 (η=1.8cP) compared with solvent 1 (η=1cP). The increase in the DNP factor was brought about by the shortening of water proton spin-lattice relaxation time of solvent 2. The decreased DNP factors (30% and 53%) were observed for solvent 3 (η=7cP) and solvent 4 (η=14cP) compared with solvent 2, which is mainly due to the low value of coupling parameter in high viscous liquid samples. The longitudinal relaxivity, leakage factor and coupling parameter were estimated. The coupling parameter values reveal that the dipolar interaction as the major mechanism. The longitudinal relaxivity increases with the increasing viscosity of pure water/glycerol mixtures. The leakage factor showed an asymptotic increase with the increasing agent concentration. It is envisaged that the results reported here may provide guidelines for the design of new viscosity prone nitroxyl radicals, suited to the biological applications of DNP.

  3. A Cross-Polarization, Magic-Angle-Spinning, 13C-Nuclear-Magnetic-Resonance Study of Polysaccharides in Sugar Beet Cell Walls1

    PubMed Central

    Renard, Catherine M.G.C.; Jarvis, Michael C.

    1999-01-01

    Solid-state nuclear magnetic resonance relaxation experiments were used to study the rigidity and spatial proximity of polymers in sugar beet (Beta vulgaris) cell walls. Proton T1ρ decay and cross-polarization patterns were consistent with the presence of rigid, crystalline cellulose microfibrils with a diameter of approximately 3 nm, mobile pectic galacturonans, and highly mobile arabinans. A direct-polarization, magic-angle-spinning spectrum recorded under conditions adapted to mobile polymers showed only the arabinans, which had a conformation similar to that of beet arabinans in solution. These cell walls contained very small amounts of hemicellulosic polymers such as xyloglucan, xylan, and mannan, and no arabinan or galacturonan fraction closely associated with cellulose microfibrils, as would be expected of hemicelluloses. Cellulose microfibrils in the beet cell walls were stable in the absence of any polysaccharide coating. PMID:10198090

  4. Mechanism of Solid-State Thermolysis of Ammonia Boraine: 15N NMR Study Using Fast Magic-Angle Spinning and Dynamic Nuclear Polarization

    SciTech Connect

    Kobayashi, Takeshi; Gupta, Shalabh; Caporini, Marc A; Pecharsky, Vitalij K; Pruski, Marek

    2014-08-28

    The solid-state thermolysis of ammonia borane (NH3BH3, AB) was explored using state-of-the-art 15N solid-state NMR spectroscopy, including 2D indirectly detected 1H{15N} heteronuclear correlation and dynamic nuclear polarization (DNP)-enhanced 15N{1H} cross-polarization experiments as well as 11B NMR. The complementary use of 15N and 11B NMR experiments, supported by density functional theory calculations of the chemical shift tensors, provided insights into the dehydrogenation mechanism of AB—insights that have not been available by 11B NMR alone. Specifically, highly branched polyaminoborane derivatives were shown to form from AB via oligomerization in the “head-to-tail” manner, which then transform directly into hexagonal boron nitride analog through the dehydrocyclization reaction, bypassing the formation of polyiminoborane.

  5. Atomic Description of the Interface between Silica and Alumina in Aluminosilicates through Dynamic Nuclear Polarization Surface-Enhanced NMR Spectroscopy and First-Principles Calculations.

    PubMed

    Valla, Maxence; Rossini, Aaron J; Caillot, Maxime; Chizallet, Céline; Raybaud, Pascal; Digne, Mathieu; Chaumonnot, Alexandra; Lesage, Anne; Emsley, Lyndon; van Bokhoven, Jeroen A; Copéret, Christophe

    2015-08-26

    Despite the widespread use of amorphous aluminosilicates (ASA) in various industrial catalysts, the nature of the interface between silica and alumina and the atomic structure of the catalytically active sites are still subject to debate. Here, by the use of dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP SENS) and density functional theory (DFT) calculations, we show that on silica and alumina surfaces, molecular aluminum and silicon precursors are, respectively, preferentially grafted on sites that enable the formation of Al(IV) and Si(IV) interfacial sites. We also link the genesis of Brønsted acidity to the surface coverage of aluminum and silicon on silica and alumina, respectively.

  6. Process dependent nuclear k⊥ broadening effect

    NASA Astrophysics Data System (ADS)

    Schäfer, Andreas; Zhou, Jian

    2013-10-01

    We study the process dependent nuclear k⊥ broadening effect by employing the transverse momentum dependent (TMD) factorization approach in combination with the Mclerran-Venugopalan model. More specifically, we investigate how the parton transverse momentum distributions are affected by the process dependent gauge links in cold nuclear matter. In particular, our analysis also applies to the polarized cases including the nuclear quark Boer-Mulders function and the linearly polarized gluon distribution. Our main focus is on the nuclear TMDs at intermediate or large x.

  7. Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

    SciTech Connect

    Liu, X. H.; Luo, H.; Qu, T. L. Yang, K. Y.; Ding, Z. C.

    2015-10-15

    We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of {sup 87}Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the {sup 87}Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the {sup 87}Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system.

  8. Polarization at SLAC

    SciTech Connect

    Woods, M.

    1995-01-01

    A highly polarized electron beam is a key feature. for the Current physics program at SLAC. An electron beam polarization of 80% can now be routinely achieved for typically 5000 hours of machine operation per year. Two main Physics programs utilize the polarized beam. Fixed target experiments in End Station A study the collision of polarized electrons with polarized nuclear targets to elucidate the spin structure of the nucleon and to provide an important test of QCD. Using the SLAC Linear Collider, collisions of polarized electrons with unpolarized positrons allow precise measurements of parity violation in the Z-fermion couplings and provide a very precise measurement of tile weak mixing angle. This paper discusses polarized beam operation at SLAC, and gives an overview of the polarized physics program.

  9. Microwave frequency modulation for improving polarization transfer in DNP experiments

    NASA Astrophysics Data System (ADS)

    Guy, Mallory; Ramanathan, Chandrasekhar

    Dynamic nuclear polarization (DNP) is a driven process that transfers the inherently high electron polarization to surrounding nuclear spins via microwave irradiation at or near the electron Larmor frequency. In a typical DNP experiment, the amplitude and frequency of the applied microwaves are constant. However, by adding time dependence in the form of frequency modulation, the electron excitation bandwidth is increased, thereby increasing the number of electron spins active in the polarization transfer process and improving overall efficiency. Both triangular and sinusoidal modulation show a 3 fold improvement over monochromatic irradiation. In the present study, we compare the nuclear spin polarization after DNP experiments with no modulation of the applied microwaves, triangular and sinusoidal modulation, and modulation schemes derived from the sample's ESR spectrum. We characterize the polarization as a function of the modulation amplitude and frequency and compare the optimal results from each modulation scheme. Working at a field of 3.34 T and at a temperature of 4 K, we show that by using a modulation scheme tailored to the electronic environment of the sample, polarization transfer is improved over other modulation schemes. Small-scale simulations of the spin system are developed to gain further insight into the dynamics of this driven open system. This understanding could enable the design of modulation schemes to achieve even higher polarization transfer efficiencies. With support from NSF (CHE-1410504) and by NIH (U19-A1091173).

  10. The role of Pleistocene glaciations in shaping the evolution of polar and brown bears. Evidence from a critical review of mitochondrial and nuclear genome analyses.

    PubMed

    Hassanin, Alexandre

    2015-07-01

    In this report, I review recent molecular studies dealing with the origin and evolution of polar bears (Ursus maritimus), with special emphasis on their relationships with brown bears (U. arctos). On the basis of mitochondrial and nuclear data, different hypotheses have been proposed, including rapid morphological differentiation of U. maritimus, genetic introgression from U. arctos into U. maritimus, or inversely from U. maritimus into U. arctos, involving either male- or female-mediated gene flow. In the light of available molecular and eco-ethological data, I suggest, firstly, that all divergences among major clades of large bears can be linked to glacial periods, secondly, that polar bears diverged from brown bears before 530 thousand years ago (ka), during one of the three glacial marine isotope stages (MIS) 14, 15.2 or 16, and, thirdly, that genetic introgression had occurred from female polar bears into brown bear populations during at least two glacial periods, at 340 ± 10 ka (MIS 10) in western Europe, and at 155 ± 5 ka (MIS 6) on the ABC islands of southeastern Alaska, and probably also in Beringia and Ireland based on ancient DNA sequences.

  11. The role of Pleistocene glaciations in shaping the evolution of polar and brown bears. Evidence from a critical review of mitochondrial and nuclear genome analyses.

    PubMed

    Hassanin, Alexandre

    2015-07-01

    In this report, I review recent molecular studies dealing with the origin and evolution of polar bears (Ursus maritimus), with special emphasis on their relationships with brown bears (U. arctos). On the basis of mitochondrial and nuclear data, different hypotheses have been proposed, including rapid morphological differentiation of U. maritimus, genetic introgression from U. arctos into U. maritimus, or inversely from U. maritimus into U. arctos, involving either male- or female-mediated gene flow. In the light of available molecular and eco-ethological data, I suggest, firstly, that all divergences among major clades of large bears can be linked to glacial periods, secondly, that polar bears diverged from brown bears before 530 thousand years ago (ka), during one of the three glacial marine isotope stages (MIS) 14, 15.2 or 16, and, thirdly, that genetic introgression had occurred from female polar bears into brown bear populations during at least two glacial periods, at 340 ± 10 ka (MIS 10) in western Europe, and at 155 ± 5 ka (MIS 6) on the ABC islands of southeastern Alaska, and probably also in Beringia and Ireland based on ancient DNA sequences. PMID:26026577

  12. Response to comment on "Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage".

    PubMed

    Hailer, Frank; Kutschera, Verena E; Hallström, Björn M; Fain, Steven R; Leonard, Jennifer A; Arnason, Ulfur; Janke, Axel

    2013-03-29

    Nakagome et al. reanalyzed some of our data and assert that we cannot refute the mitochondrial DNA-based scenario for polar bear evolution. Their single-locus test statistic is strongly affected by introgression and incomplete lineage sorting, whereas our multilocus approaches are better suited to recover the true species relationships. Indeed, our sister-lineage model receives high support in a Bayesian model comparison.

  13. Broadband Adiabatic Inversion Pulses for Cross-Polarization in Wideline Solid-State Nuclear Magnetic Resonance Spectroscopy

    PubMed Central

    Harris, Kristopher J.; Lupulescu, Adonis; Lucier, Bryan E. G.; Frydman, Lucio; Schurko, Robert W.

    2016-01-01

    Efficient acquisition of wideline solid-state NMR powder patterns is a continuing challenge. In particular, when the breadth of the powder pattern is much larger than the cross-polarization (CP) excitation bandwidth, transfer efficiencies suffer and experimental times are greatly increased. Presented herein is a CP pulse sequence with an excitation bandwidth that is up to ten times greater than that available from a conventional spin-locked CP pulse sequence. The pulse sequence, broadband adiabatic inversion CP (BRAIN-CP), makes use of the broad, uniformly large frequency profiles of inversion chirped pulses, to provide these same characteristics to the polarization transfer process. A detailed theoretical analysis is given, providing insight into the polarization transfer process involved in BRAIN-CP. Experiments on spin-1/2 nuclei including 119Sn, 199Hg and 195Pt nuclei are presented, and the large bandwidth improvements possible with BRAIN-CP are demonstrated. Furthermore, it is shown that BRAIN-CP can be combined with broadband frequency-swept versions of the Carr-Purcell-Meiboom-Gill experiment (for instance with WURST-CPMG, or WCPMG for brevity); the combined BRAIN-CP/WCPMG experiment then provides multiplicative signal enhancements of both CP and multiple-echo acquisition over a broad frequency region. PMID:23023623

  14. 27Al-->1H cross-polarization in aluminosilicates.

    PubMed

    Kolodziejski, W; Corma, A

    1994-06-01

    Solid-state nuclear magnetic resonance (NMR) cross-polarization (CP) from 27Al to 1H was set on kaolinite, verified by a variable-contact time experiment and applied to ultrastable zeolite Y. The technique is useful for the selective NMR observation of AlOH sites in aluminosilicates, especially those from extraframework species in zeolites.

  15. Level crossing analysis of chemically induced dynamic nuclear polarization: Towards a common description of liquid-state and solid-state cases

    NASA Astrophysics Data System (ADS)

    Sosnovsky, Denis V.; Jeschke, Gunnar; Matysik, Jörg; Vieth, Hans-Martin; Ivanov, Konstantin L.

    2016-04-01

    Chemically Induced Dynamic Nuclear Polarization (CIDNP) is an efficient method of creating non-equilibrium polarization of nuclear spins by using chemical reactions, which have radical pairs as intermediates. The CIDNP effect originates from (i) electron spin-selective recombination of radical pairs and (ii) the dependence of the inter-system crossing rate in radical pairs on the state of magnetic nuclei. The CIDNP effect can be investigated by using Nuclear Magnetic Resonance (NMR) methods. The gain from CIDNP is then two-fold: it allows one to obtain considerable amplification of NMR signals; in addition, it provides a very useful tool for investigating elusive radicals and radical pairs. While the mechanisms of the CIDNP effect in liquids are well established and understood, detailed analysis of solid-state CIDNP mechanisms still remains challenging; likewise a common theoretical frame for the description of CIDNP in both solids and liquids is missing. Difficulties in understanding the spin dynamics that lead to the CIDNP effect in the solid-state case are caused by the anisotropy of spin interactions, which increase the complexity of spin evolution. In this work, we propose to analyze CIDNP in terms of level crossing phenomena, namely, to attribute features in the CIDNP magnetic field dependence to Level Crossings (LCs) and Level Anti-Crossings (LACs) in a radical pair. This approach allows one to describe liquid-state CIDNP; the same holds for the solid-state case where anisotropic interactions play a significant role in CIDNP formation. In solids, features arise predominantly from LACs, since in most cases anisotropic couplings result in perturbations, which turn LCs into LACs. We have interpreted the CIDNP mechanisms in terms of the LC/LAC concept. This consideration allows one to find analytical expressions for a wide magnetic field range, where several different mechanisms are operative; furthermore, the LAC description gives a way to determine CIDNP sign

  16. Level crossing analysis of chemically induced dynamic nuclear polarization: Towards a common description of liquid-state and solid-state cases.

    PubMed

    Sosnovsky, Denis V; Jeschke, Gunnar; Matysik, Jörg; Vieth, Hans-Martin; Ivanov, Konstantin L

    2016-04-14

    Chemically Induced Dynamic Nuclear Polarization (CIDNP) is an efficient method of creating non-equilibrium polarization of nuclear spins by using chemical reactions, which have radical pairs as intermediates. The CIDNP effect originates from (i) electron spin-selective recombination of radical pairs and (ii) the dependence of the inter-system crossing rate in radical pairs on the state of magnetic nuclei. The CIDNP effect can be investigated by using Nuclear Magnetic Resonance (NMR) methods. The gain from CIDNP is then two-fold: it allows one to obtain considerable amplification of NMR signals; in addition, it provides a very useful tool for investigating elusive radicals and radical pairs. While the mechanisms of the CIDNP effect in liquids are well established and understood, detailed analysis of solid-state CIDNP mechanisms still remains challenging; likewise a common theoretical frame for the description of CIDNP in both solids and liquids is missing. Difficulties in understanding the spin dynamics that lead to the CIDNP effect in the solid-state case are caused by the anisotropy of spin interactions, which increase the complexity of spin evolution. In this work, we propose to analyze CIDNP in terms of level crossing phenomena, namely, to attribute features in the CIDNP magnetic field dependence to Level Crossings (LCs) and Level Anti-Crossings (LACs) in a radical pair. This approach allows one to describe liquid-state CIDNP; the same holds for the solid-state case where anisotropic interactions play a significant role in CIDNP formation. In solids, features arise predominantly from LACs, since in most cases anisotropic couplings result in perturbations, which turn LCs into LACs. We have interpreted the CIDNP mechanisms in terms of the LC/LAC concept. This consideration allows one to find analytical expressions for a wide magnetic field range, where several different mechanisms are operative; furthermore, the LAC description gives a way to determine CIDNP sign

  17. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes

    SciTech Connect

    Wiesinger, R.; Schade, U.; Kleber, Ch.; Schreiner, M.

    2014-06-15

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  18. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes.

    PubMed

    Wiesinger, R; Schade, U; Kleber, Ch; Schreiner, M

    2014-06-01

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  19. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes

    NASA Astrophysics Data System (ADS)

    Wiesinger, R.; Schade, U.; Kleber, Ch.; Schreiner, M.

    2014-06-01

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  20. A method for the compensation of the effects of surface cloth impressions on polar backscatter applied to porous epoxy and biaxial graphite/epoxy composites

    NASA Technical Reports Server (NTRS)

    Madaras, Eric I.; Bridal, S. L.; Holland, Mark R.; Handley, Scott M.; Miller, James G.

    1993-01-01

    The anisotropy of polar backscatter from graphite/epoxy composites is a potentially useful parameter for the characterization of porosity levels. However, the effects of release-cloth impressions on measured integrated polar backscatter levels are sufficient to inhibit the detection of porosity with this method. Recently, we developed a theoretical model to predict the frequency distribution of the backscattered power along the high-symmetry directions of release-cloth impressions. This study investigates experimentally the usefulness of limiting the bandwidth to regions not dominated by the scattering from the surface impressions, hence increasing the probability of detecting flaws such as porosity.

  1. Atomic Description of the Interface between Silica and Alumina in Aluminosilicates through Dynamic Nuclear Polarization Surface-Enhanced NMR Spectroscopy and First-Principles Calculations

    PubMed Central

    2015-01-01

    Despite the widespread use of amorphous aluminosilicates (ASA) in various industrial catalysts, the nature of the interface between silica and alumina and the atomic structure of the catalytically active sites are still subject to debate. Here, by the use of dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP SENS) and density functional theory (DFT) calculations, we show that on silica and alumina surfaces, molecular aluminum and silicon precursors are, respectively, preferentially grafted on sites that enable the formation of Al(IV) and Si(IV) interfacial sites. We also link the genesis of Brønsted acidity to the surface coverage of aluminum and silicon on silica and alumina, respectively. PMID:26244620

  2. (13)C-labeled biochemical probes for the study of cancer metabolism with dynamic nuclear polarization-enhanced magnetic resonance imaging.

    PubMed

    Salamanca-Cardona, Lucia; Keshari, Kayvan R

    2015-01-01

    In recent years, advances in metabolic imaging have become dependable tools for the diagnosis and treatment assessment in cancer. Dynamic nuclear polarization (DNP) has recently emerged as a promising technology in hyperpolarized (HP) magnetic resonance imaging (MRI) and has reached clinical relevance with the successful visualization of [1-(13)C] pyruvate as a molecular imaging probe in human prostate cancer. This review focuses on introducing representative compounds relevant to metabolism that are characteristic of cancer tissue: aerobic glycolysis and pyruvate metabolism, glutamine addiction and glutamine/glutamate metabolism, and the redox state and ascorbate/dehydroascorbate metabolism. In addition, a brief introduction of probes that can be used to trace necrosis, pH changes, and other pathways relevant to cancer is presented to demonstrate the potential that HP MRI has to revolutionize the use of molecular imaging for diagnosis and assessment of treatments in cancer.

  3. Solid-State Dynamic Nuclear Polarization at 9.4 and 18.8 T from 100 K to Room Temperature

    PubMed Central

    2015-01-01

    Efficient dynamic nuclear polarization (DNP) in solids, which enables very high sensitivity NMR experiments, is currently limited to temperatures of around 100 K and below. Here we show how by choosing an adequate solvent, 1H cross effect DNP enhancements of over 80 can be obtained at 240 K. To achieve this we use the biradical TEKPol dissolved in a glassy phase of ortho-terphenyl (OTP). We study the solvent DNP enhancement of both TEKPol and BDPA in OTP in the range from 100 to 300 K at 9.4 and 18.8 T. Surprisingly, we find that the DNP enhancement decreases only relatively slowly for temperatures below the glass transition of OTP (Tg = 243 K), and 1H enhancements around 15–20 at ambient temperature can be observed. We use this to monitor molecular dynamic transitions in the pharmaceutically relevant solids Ambroxol and Ibuprofen. PMID:26555676

  4. Atomic Description of the Interface between Silica and Alumina in Aluminosilicates through Dynamic Nuclear Polarization Surface-Enhanced NMR Spectroscopy and First-Principles Calculations.

    PubMed

    Valla, Maxence; Rossini, Aaron J; Caillot, Maxime; Chizallet, Céline; Raybaud, Pascal; Digne, Mathieu; Chaumonnot, Alexandra; Lesage, Anne; Emsley, Lyndon; van Bokhoven, Jeroen A; Copéret, Christophe

    2015-08-26

    Despite the widespread use of amorphous aluminosilicates (ASA) in various industrial catalysts, the nature of the interface between silica and alumina and the atomic structure of the catalytically active sites are still subject to debate. Here, by the use of dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP SENS) and density functional theory (DFT) calculations, we show that on silica and alumina surfaces, molecular aluminum and silicon precursors are, respectively, preferentially grafted on sites that enable the formation of Al(IV) and Si(IV) interfacial sites. We also link the genesis of Brønsted acidity to the surface coverage of aluminum and silicon on silica and alumina, respectively. PMID:26244620

  5. Climate Drives Polar Bear Origins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In their provocative analysis of northern bears (“Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage,” Reports, 20 April, p. 344), F. Hailer et al. use independent nuclear loci to show that polar bears originated during the middle Pleistocene, rather than during t...

  6. Helium-cooling and -spinning dynamic nuclear polarization for sensitivity-enhanced solid-state NMR at 14 T and 30 K

    NASA Astrophysics Data System (ADS)

    Matsuki, Yoh; Ueda, Keisuke; Idehara, Toshitaka; Ikeda, Ryosuke; Ogawa, Isamu; Nakamura, Shinji; Toda, Mitsuru; Anai, Takahiro; Fujiwara, Toshimichi

    2012-12-01

    We describe a 1H polarization enhancement via dynamic nuclear polarization (DNP) at very low sample temperature T ≈ 30 K under magic-angle spinning (MAS) conditions for sensitivity-enhanced solid-state NMR measurement. Experiments were conducted at a high external field strength of 14.1 T. For MAS DNP experiments at T ≪ 90 K, a new probe system using cold helium gas for both sample-cooling and -spinning was developed. The novel system can sustain a low sample temperature between 30 and 90 K for a period of time >10 h under MAS at νR ≈ 3 kHz with liquid He consumption of ≈6 L/h. As a microwave source, we employed a high-power, continuously frequency-tunable gyrotron. At T ≈ 34 K, 1H DNP enhancement factors of 47 and 23 were observed with and without MAS, respectively. On the basis of these observations, a discussion on the total NMR sensitivity that takes into account the effect of sample temperature and external field strength used in DNP experiments is presented. It was determined that the use of low sample temperature and high external field is generally rewarding for the total sensitivity, in spite of the slower polarization buildup at lower temperature and lower DNP efficiency at higher field. These findings highlight the potential of the current continuous-wave DNP technique also at very high field conditions suitable to analyze large and complex systems, such as biological macromolecules.

  7. The isotropic nuclear magnetic shielding constants of acetone in supercritical water: a sequential Monte Carlo/quantum mechanics study including solute polarization.

    PubMed

    Fonseca, Tertius L; Coutinho, Kaline; Canuto, Sylvio

    2008-07-21

    The nuclear isotropic shielding constants sigma((17)O) and sigma((13)C) of the carbonyl bond of acetone in water at supercritical (P=340.2 atm and T=673 K) and normal water conditions have been studied theoretically using Monte Carlo simulation and quantum mechanics calculations based on the B3LYP6-311++G(2d,2p) method. Statistically uncorrelated configurations have been obtained from Monte Carlo simulations with unpolarized and in-solution polarized solute. The results show that solvent effects on the shielding constants have a significant contribution of the electrostatic interactions and that quantitative estimates for solvent shifts of shielding constants can be obtained modeling the water molecules by point charges (electrostatic embedding). In supercritical water, there is a decrease in the magnitude of sigma((13)C) but a sizable increase in the magnitude of sigma((17)O) when compared with the results obtained in normal water. It is found that the influence of the solute polarization is mild in the supercritical regime but it is particularly important for sigma((17)O) in normal water and its shielding effect reflects the increase in the average number of hydrogen bonds between acetone and water. Changing the solvent environment from normal to supercritical water condition, the B3LYP6-311++G(2d,2p) calculations on the statistically uncorrelated configurations sampled from the Monte Carlo simulation give a (13)C chemical shift of 11.7+/-0.6 ppm for polarized acetone in good agreement with the experimentally inferred result of 9-11 ppm.

  8. Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning 13C and 29Si NMR Enhanced by Dynamic Nuclear Polarization

    SciTech Connect

    Lafon, Olivier; Thankamony, Aany S. Lilly; Kokayashi, Takeshi; Carnevale, Diego; Vitzthum, Veronika; Slowing, Igor I.; Kandel, Kapil; Vezin, Herve; Amoureux, Jean-Paul; Bodenhausen, Geoffrey; Pruski, Marek

    2012-12-21

    We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of 13C and 29Si nuclei located in mesoporous organic/inorganic hybrid materials, at several hundreds of nanometers from stable radicals (TOTAPOL) trapped in the surrounding frozen disordered water. The approach is demonstrated using mesoporous silica nanoparticles (MSN), functionalized with 3-(N-phenylureido)propyl (PUP) groups, filled with the surfactant cetyltrimethylammonium bromide (CTAB). The DNP-enhanced proton magnetization is transported into the mesopores via 1H–1H spin diffusion and transferred to rare spins by cross-polarization, yielding signal enhancements εon/off of around 8. When the CTAB molecules are extracted, so that the radicals can enter the mesopores, the enhancements increase to εon/off ≈ 30 for both nuclei. A quantitative analysis of the signal enhancements in MSN with and without surfactant is based on a one-dimensional proton spin diffusion model. The effect of solvent deuteration is also investigated.

  9. Dynamic Nuclear Polarization of 1H, 13C, and 59Co in a Tris(ethylenediamine)cobalt(III) Crystalline Lattice Doped with Cr(III)

    PubMed Central

    2015-01-01

    The study of inorganic crystalline materials by solid-state NMR spectroscopy is often complicated by the low sensitivity of heavy nuclei. However, these materials often contain or can be prepared with paramagnetic dopants without significantly affecting the structure of the crystalline host. Dynamic nuclear polarization (DNP) is generally capable of enhancing NMR signals by transferring the magnetization of unpaired electrons to the nuclei. Therefore, the NMR sensitivity in these paramagnetically doped crystals might be increased by DNP. In this paper we demonstrate the possibility of efficient DNP transfer in polycrystalline samples of [Co(en)3Cl3]2·NaCl·6H2O (en = ethylenediamine, C2H8N2) doped with Cr(III) in varying concentrations between 0.1 and 3 mol %. We demonstrate that 1H, 13C, and 59Co can be polarized by irradiation of Cr(III) with 140 GHz microwaves at a magnetic field of 5 T. We further explain our findings on the basis of electron paramagnetic resonance spectroscopy of the Cr(III) site and analysis of its temperature-dependent zero-field splitting, as well as the dependence of the DNP enhancement factor on the external magnetic field and microwave power. This first demonstration of DNP transfer from one paramagnetic metal ion to its diamagnetic host metal ion will pave the way for future applications of DNP in paramagnetically doped materials or metalloproteins. PMID:25069794

  10. Polarized negative ions

    SciTech Connect

    Haeberli, W.

    1981-04-01

    This paper presents a survey of methods, commonly in use or under development, to produce beams of polarized negative ions for injection into accelerators. A short summary recalls how the hyperfine interaction is used to obtain nuclear polarization in beams of atoms. Atomic-beam sources for light ions are discussed. If the best presently known techniques are incorporated in all stages of the source, polarized H/sup -/ and D/sup -/ beams in excess of 10 ..mu..A can probably be achieved. Production of polarized ions from fast (keV) beams of polarized atoms is treated separately for atoms in the H(25) excited state (Lamb-Shift source) and atoms in the H(1S) ground state. The negative ion beam from Lamb-Shift sources has reached a plateau just above 1 ..mu..A, but this beam current is adequate for many applications and the somewhat lower beam current is compensated by other desirable characteristics. Sources using fast polarized ground state atoms are in a stage of intense development. The next sections summarize production of polarized heavy ions by the atomic beam method, which is well established, and by optical pumping, which has recently been demonstrated to yield very large nuclear polarization. A short discussion of proposed ion sources for polarized /sup 3/He/sup -/ ions is followed by some concluding remarks.

  11. Influence of non-aqueous phase liquid configuration on induced polarization parameters: Conceptual models applied to a time-domain field case study

    NASA Astrophysics Data System (ADS)

    Johansson, Sara; Fiandaca, Gianluca; Dahlin, Torleif

    2015-12-01

    Resistivity and induced polarization (IP) measurements on soil contaminated with non-aqueous phase liquids (NAPLs) show a great variety in results in previous research. Several laboratory studies have suggested that the presence of NAPLs in soil samples generally decrease the magnitude of the IP-effect, while others have indicated the opposite. A number of conceptual models have been proposed suggesting that NAPLs can alter the pore space in different ways, e.g. by coating the grain surfaces and thus inhibiting grain polarization, or by changing the pore throat size and thus affecting the membrane polarization mechanism. The main aim of this paper is to review previously published conceptual models and to introduce some new concepts of possible residual NAPL configurations in the pore space. Time domain induced polarization measurements were performed at a NAPL contaminated field site, and the data were inverted using the Constant Phase Angle (CPA) model and the Cole-Cole model respectively. No significant phase anomalies were observed in the source area of the contamination when the CPA inverted profiles were compared with soil sampling results of free-phase contaminant concentrations. However, relatively strong phase and normalized phase anomalies appeared next to the source area, where residual free-phase presence could be expected according to the chemical data. We conclude that depending on the NAPL configuration, different spectral IP responses can be expected. In previous research, the NAPL configurations in different samples or field sites are often unknown, and this may to some extent explain why different results have been achieved by different authors. In our field case, we believe that the NAPL forms a more or less continuous phase in the pore space of the source zone leading to an absence of IP anomalies. The increase in phase and normalized phase angle observed next to the source zone is interpreted as a degradation zone. The ongoing biodegradation

  12. Membrane topologies of the PGLa antimicrobial peptide and a transmembrane anchor sequence by Dynamic Nuclear Polarization/solid-state NMR spectroscopy

    PubMed Central

    Salnikov, Evgeniy Sergeevich; Aisenbrey, Christopher; Aussenac, Fabien; Ouari, Olivier; Sarrouj, Hiba; Reiter, Christian; Tordo, Paul; Engelke, Frank; Bechinger, Burkhard

    2016-01-01

    Dynamic Nuclear Polarization (DNP) has been introduced to overcome the sensitivity limitations of nuclear magnetic resonance (NMR) spectroscopy also of supported lipid bilayers. When investigated by solid-state NMR techniques the approach typically involves doping the samples with biradicals and their investigation at cryo-temperatures. Here we investigated the effects of temperature and membrane hydration on the topology of amphipathic and hydrophobic membrane polypeptides. Although the antimicrobial PGLa peptide in dimyristoyl phospholipids is particularly sensitive to topological alterations, the DNP conditions represent well its membrane alignment also found in bacterial lipids at ambient temperature. With a novel membrane-anchored biradical and purpose-built hardware a 17-fold enhancement in NMR signal intensity is obtained by DNP which is one of the best obtained for a truly static matrix-free system. Furthermore, a membrane anchor sequence encompassing 19 hydrophobic amino acid residues was investigated. Although at cryotemperatures the transmembrane domain adjusts it membrane tilt angle by about 10 degrees, the temperature dependence of two-dimensional separated field spectra show that freezing the motions can have beneficial effects for the structural analysis of this sequence. PMID:26876950

  13. Depletion of Aspergillus nidulans cotA causes a severe polarity defect which is not suppressed by the nuclear migration mutation nudA2.

    PubMed

    Johns, Sarah Anne; Leeder, Abigail Claire; Safaie, Mehran; Turner, Geoffrey

    2006-06-01

    The Aspergillus nidulans homologue of Neurospora crassa cot-1, cotA, encoding a member of the NDR protein kinase family, has been cloned and expressed under the control of the conditional alcA promoter. Depletion of CotA by repression of the alcA promoter led to a severe growth defect accompanied by loss of polarity. Germlings show greatly enlarged volume of the spores and hyphae, accompanied by an increase in number of nuclei per compartment, though the nucleus/volume ratio is not significantly altered. The depleted CotA phenotype was not suppressed by a nuclear migration mutation nudA2. Double mutants showed an additive, defective phenotype, unlike the suppression of the cot-1 ts mutation by ropy mutations seen in N. crassa, suggesting a different relationship between nuclear migration and the cot signalling pathway in A. nidulans. A functional CotA-GFP fusion protein was found in punctate regions of fluorescence similar to the distribution reported for human NDR2, and as a cap at the hyphal tip.

  14. Physical processes in spin polarized plasmas

    SciTech Connect

    Kulsrud, R.M.; Valeo, E.J.; Cowley, S.

    1984-05-01

    If the plasma in a nuclear fusion reactor is polarized, the nuclear reactions are modified in such a way as to enhance the reactor performance. We calculate in detail the modification of these nuclear reactions by different modes of polarization of the nuclear fuel. We also consider in detail the various physical processes that can lead to depolarization and show that they are by and large slow enough that a high degree of polarization can be maintained.

  15. Substrate affinities for membrane transport proteins determined by 13C cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy.

    PubMed

    Patching, Simon G; Brough, Adrian R; Herbert, Richard B; Rajakarier, J Anton; Henderson, Peter J F; Middleton, David A

    2004-03-17

    We have devised methods in which cross-polarization magic-angle spinning (CP-MAS) solid-state NMR is exploited to measure rigorous parameters for binding of (13)C-labeled substrates to membrane transport proteins. The methods were applied to two proteins from Escherichia coli: a nucleoside transporter, NupC, and a glucuronide transporter, GusB. A substantial signal for the binding of methyl [1-(13)C]-beta-d-glucuronide to GusB overexpressed in native membranes was achieved with a sample that contained as little as 20 nmol of GusB protein. The data were fitted to yield a K(D) value of 4.17 mM for the labeled ligand and 0.42 mM for an unlabeled ligand, p-nitrophenyl beta-d-glucuronide, which displaced the labeled compound. CP-MAS was also used to measure binding of [1'-(13)C]uridine to overexpressed NupC. The spectrum of NupC-enriched membranes containing [1'-(13)C]uridine exhibited a large peak from substrate bound to undefined sites other than the transport site, which obscured the signal from substrate bound to NupC. In a novel application of a cross-polarization/polarization-inversion (CPPI) NMR experiment, the signal from undefined binding was eliminated by use of appropriate inversion pulse lengths. By use of CPPI in a titration experiment, a K(D) value of 2.6 mM was determined for uridine bound to NupC. These approaches are broadly applicable to quantifying binding of substrates, inhibitors, drugs, and antibiotics to numerous membrane proteins. PMID:15012136

  16. Development of the quantum theory of T-odd asymmetries for prescission and evaporated third particles in ternary nuclear fission induced by cold polarized neutrons

    SciTech Connect

    Kadmensky, S. G.; Bunakov, V. E.; Titova, L. V.; Kadmensky, S. S.

    2011-10-15

    A comparative analysis of the results obtained by experimentally and theoretically studying T-odd asymmetries for various third particles in the true and delayed ternary nuclear fission induced by cold polarized neutrons was performed. It was confirmed that the appearance of these asymmetries was associated with the effect of rotation of a polarized system undergoing fission on the angular distributions of prescission and evaporated third particles with respect to the direction along which the emerging fission fragments flew apart, this effect being determined by the Coriolis interaction of the rotational and the internalmotion of the fissioning system. A quantum-mechanical description of particle motion in a rotating coordinate system was generalized to the case where gamma-ray emission was present. It was shown that the separation of the motions of an axially symmetric fissile system into a rotational and an internal motion was valid in the external region as well, where ternary-fission products had already been formed, if it was considered that the motion of fission fragments was tightly connected with the system symmetry axis, which rotated in the laboratory frame. It was found that the dependence of the fissile-system moment of inertia appearing in the Coriolis interaction Hamiltonian on the distance between the fission fragments flying apart generated an additional phase in the amplitude of the radial distribution of fission fragments. It was shown that this phase might change sizably the contribution of the interference between fission amplitudes of neutron resonances excited in a fissile compound nucleus to the absolute values of T -odd asymmetries, especially for third particles such as neutrons and photons, which interacted only slightly with fission fragments.

  17. Master equation theory applied to the redistribution of polarized radiation in the weak radiation field limit. IV. Application to the second solar spectrum of the Na i D1 and D2 lines

    NASA Astrophysics Data System (ADS)

    Bommier, Véronique

    2016-06-01

    Context. The spectrum of the linear polarization, which is formed by scattering and observed on the solar disk close to the limb, is very different from the intensity spectrum and thus able to provide new information, in particular about anisotropies in the solar surface plasma and magnetic fields. In addition, a large number of lines show far wing polarization structures assigned to partial redistribution (PRD), which we prefer to denote as Rayleigh/Raman scattering. The two-level or two-term atom approximation without any lower level polarization is insufficient for many lines. Aims: In the previous paper of this series, we presented our theory generalized to the multilevel and multiline atom and comprised of statistical equilibrium equations for the atomic density matrix elements and radiative transfer equation for the polarized radiation. The present paper is devoted to applying this theory to model the second solar spectrum of the Na i D1 and D2 lines. Methods: The solution method is iterative, of the lambda-iteration type. The usual acceleration techniques were considered or even applied, but we found these to be unsuccessful, in particular because of nonlinearity or large number of quantities determining the radiation at each depth. Results: The observed spectrum is qualitatively reproduced in line center, but the convergence is yet to be reached in the far wings and the observed spectrum is not totally reproduced there. Conclusions: We need to investigate noniterative resolution methods. The other limitation lies in the one-dimensional (1D) atmosphere model, which is unable to reproduce the intermittent matter structure formed of small loops or spicules in the chromosphere. This modeling is rough, but the computing time in the presence of hyperfine structure and PRD prevents us from envisaging a three-dimensional (3D) model at this instant.

  18. Multi-matrix, dual polarity, tandem mass spectrometry imaging strategy applied to a germinated maize seed: toward mass spectrometry imaging of an untargeted metabolome

    DOE PAGES

    Feenstra, Adam D.; Hansen, Rebecca L.; Lee, Young Jin

    2015-08-27

    Mass spectrometry imaging (MSI) provides high spatial resolution information that is unprecedented in traditional metabolomics analyses; however, the molecular coverage is often limited to a handful of compounds and is insufficient to understand overall metabolomic changes of a biological system. Here, we propose an MSI methodology to increase the diversity of chemical compounds that can be imaged and identified, in order to eventually perform untargeted metabolomic analysis using MSI. We use the desorption/ionization bias of various matrixes for different metabolite classes along with dual polarities and a tandem MSI strategy. The use of multiple matrixes and dual polarities allows usmore » to visualize various classes of compounds, while data-dependent MS/MS spectra acquired in the same MSI scans allow us to identify the compounds directly on the tissue. In a proof of concept application to a germinated corn seed, a total of 166 unique ions were determined to have high-quality MS/MS spectra, without counting structural isomers, of which 52 were identified as unique compounds. According to an estimation based on precursor MSI datasets, we expect over five hundred metabolites could be potentially identified and visualized once all experimental conditions are optimized and an MS/MS library is available. Finally, metabolites involved in the glycolysis pathway and tricarboxylic acid cycle were imaged to demonstrate the potential of this technology to better understand metabolic biology.« less

  19. Multi-matrix, dual polarity, tandem mass spectrometry imaging strategy applied to a germinated maize seed: toward mass spectrometry imaging of an untargeted metabolome

    SciTech Connect

    Feenstra, Adam D.; Hansen, Rebecca L.; Lee, Young Jin

    2015-08-27

    Mass spectrometry imaging (MSI) provides high spatial resolution information that is unprecedented in traditional metabolomics analyses; however, the molecular coverage is often limited to a handful of compounds and is insufficient to understand overall metabolomic changes of a biological system. Here, we propose an MSI methodology to increase the diversity of chemical compounds that can be imaged and identified, in order to eventually perform untargeted metabolomic analysis using MSI. We use the desorption/ionization bias of various matrixes for different metabolite classes along with dual polarities and a tandem MSI strategy. The use of multiple matrixes and dual polarities allows us to visualize various classes of compounds, while data-dependent MS/MS spectra acquired in the same MSI scans allow us to identify the compounds directly on the tissue. In a proof of concept application to a germinated corn seed, a total of 166 unique ions were determined to have high-quality MS/MS spectra, without counting structural isomers, of which 52 were identified as unique compounds. According to an estimation based on precursor MSI datasets, we expect over five hundred metabolites could be potentially identified and visualized once all experimental conditions are optimized and an MS/MS library is available. Finally, metabolites involved in the glycolysis pathway and tricarboxylic acid cycle were imaged to demonstrate the potential of this technology to better understand metabolic biology.

  20. Applying Human-performance Models to Designing and Evaluating Nuclear Power Plants: Review Guidance and Technical Basis

    SciTech Connect

    O'Hara, J.M.

    2009-11-30

    Human performance models (HPMs) are simulations of human behavior with which we can predict human performance. Designers use them to support their human factors engineering (HFE) programs for a wide range of complex systems, including commercial nuclear power plants. Applicants to U.S. Nuclear Regulatory Commission (NRC) can use HPMs for design certifications, operating licenses, and license amendments. In the context of nuclear-plant safety, it is important to assure that HPMs are verified and validated, and their usage is consistent with their intended purpose. Using HPMs improperly may generate misleading or incorrect information, entailing safety concerns. The objective of this research was to develop guidance to support the NRC staff's reviews of an applicant's use of HPMs in an HFE program. The guidance is divided into three topical areas: (1) HPM Verification, (2) HPM Validation, and (3) User Interface Verification. Following this guidance will help ensure the benefits of HPMs are achieved in a technically sound, defensible manner. During the course of developing this guidance, I identified several issues that could not be addressed; they also are discussed.

  1. Polarization transfer NMR imaging

    DOEpatents

    Sillerud, Laurel O.; van Hulsteyn, David B.

    1990-01-01

    A nuclear magnetic resonance (NMR) image is obtained with spatial information modulated by chemical information. The modulation is obtained through polarization transfer from a first element representing the desired chemical, or functional, information, which is covalently bonded and spin-spin coupled with a second element effective to provide the imaging data. First and second rf pulses are provided at first and second frequencies for exciting the imaging and functional elements, with imaging gradients applied therebetween to spatially separate the nuclei response for imaging. The second rf pulse is applied at a time after the first pulse which is the inverse of the spin coupling constant to select the transfer element nuclei which are spin coupled to the functional element nuclei for imaging. In a particular application, compounds such as glucose, lactate, or lactose, can be labeled with .sup.13 C and metabolic processes involving the compounds can be imaged with the sensitivity of .sup.1 H and the selectivity of .sup.13 C.

  2. Noninvasive mapping of the redox status of dimethylnitrosamine-induced hepatic fibrosis using in vivo dynamic nuclear polarization-magnetic resonance imaging

    PubMed Central

    Kawano, Takahito; Murata, Masaharu; Hyodo, Fuminori; Eto, Hinako; Kosem, Nuttavut; Nakata, Ryosuke; Hamano, Nobuhito; Piao, Jing Shu; Narahara, Sayoko; Akahoshi, Tomohiko; Hashizume, Makoto

    2016-01-01

    Hepatic fibrosis is a chronic disorder caused by viral infection and/or metabolic, genetic and cholestatic disorders. A noninvasive procedure that enables the detection of liver fibrosis based on redox status would be useful for disease identification and monitoring, and the development of treatments. However, an appropriate technique has not been reported. This study describes a novel method for assessing the redox status of the liver using in vivo dynamic nuclear polarization-magnetic resonance imaging (DNP-MRI) with the nitroxyl radical carbamoyl-PROXYL as a molecular imaging probe, which was tested in dimethylnitrosamine-treated mice as a model of liver fibrosis. Based on the pharmacokinetics of carbamoyl-PROXYL in control livers, reduction rate mapping was performed in fibrotic livers. Reduction rate maps demonstrated a clear difference between the redox status of control and fibrotic livers according to the expression of antioxidants. These findings indicate that in vivo DNP-MRI with a nitroxyl radical probe enables noninvasive detection of changes in liver redox status. PMID:27587186

  3. Noninvasive mapping of the redox status of dimethylnitrosamine-induced hepatic fibrosis using in vivo dynamic nuclear polarization-magnetic resonance imaging.

    PubMed

    Kawano, Takahito; Murata, Masaharu; Hyodo, Fuminori; Eto, Hinako; Kosem, Nuttavut; Nakata, Ryosuke; Hamano, Nobuhito; Piao, Jing Shu; Narahara, Sayoko; Akahoshi, Tomohiko; Hashizume, Makoto

    2016-09-02

    Hepatic fibrosis is a chronic disorder caused by viral infection and/or metabolic, genetic and cholestatic disorders. A noninvasive procedure that enables the detection of liver fibrosis based on redox status would be useful for disease identification and monitoring, and the development of treatments. However, an appropriate technique has not been reported. This study describes a novel method for assessing the redox status of the liver using in vivo dynamic nuclear polarization-magnetic resonance imaging (DNP-MRI) with the nitroxyl radical carbamoyl-PROXYL as a molecular imaging probe, which was tested in dimethylnitrosamine-treated mice as a model of liver fibrosis. Based on the pharmacokinetics of carbamoyl-PROXYL in control livers, reduction rate mapping was performed in fibrotic livers. Reduction rate maps demonstrated a clear difference between the redox status of control and fibrotic livers according to the expression of antioxidants. These findings indicate that in vivo DNP-MRI with a nitroxyl radical probe enables noninvasive detection of changes in liver redox status.

  4. Noninvasive mapping of the redox status of dimethylnitrosamine-induced hepatic fibrosis using in vivo dynamic nuclear polarization-magnetic resonance imaging.

    PubMed

    Kawano, Takahito; Murata, Masaharu; Hyodo, Fuminori; Eto, Hinako; Kosem, Nuttavut; Nakata, Ryosuke; Hamano, Nobuhito; Piao, Jing Shu; Narahara, Sayoko; Akahoshi, Tomohiko; Hashizume, Makoto

    2016-01-01

    Hepatic fibrosis is a chronic disorder caused by viral infection and/or metabolic, genetic and cholestatic disorders. A noninvasive procedure that enables the detection of liver fibrosis based on redox status would be useful for disease identification and monitoring, and the development of treatments. However, an appropriate technique has not been reported. This study describes a novel method for assessing the redox status of the liver using in vivo dynamic nuclear polarization-magnetic resonance imaging (DNP-MRI) with the nitroxyl radical carbamoyl-PROXYL as a molecular imaging probe, which was tested in dimethylnitrosamine-treated mice as a model of liver fibrosis. Based on the pharmacokinetics of carbamoyl-PROXYL in control livers, reduction rate mapping was performed in fibrotic livers. Reduction rate maps demonstrated a clear difference between the redox status of control and fibrotic livers according to the expression of antioxidants. These findings indicate that in vivo DNP-MRI with a nitroxyl radical probe enables noninvasive detection of changes in liver redox status. PMID:27587186

  5. A comparison of response spectrum and direct integration analysis methods as applied to a nuclear component support structure. Revision 1

    SciTech Connect

    Bryan, B.J.; Flanders, H.E. Jr.

    1992-12-31

    Seismic qualification of Class I nuclear components is accomplished using a variety of analytical methods. This paper compares the results of time history dynamic analyses of a heat exchanger support structure using response spectrum and time history direct integration analysis methods. Dynamic analysis is performed on the detailed component models using the two methods. A nonlinear elastic model is used for both the response spectrum and direct integration methods. A nonlinear model which includes friction and nonlinear springs, is analyzed using time history input by direct integration. The loads from the three cases are compared.

  6. Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors.

    PubMed

    Yang, Xianghua; Fox, Thomas; Berke, Heinz

    2012-01-28

    Metal-free transfer hydrogenation of polarized olefins (RR'C=CEE': R, R' = H or organyl, E, E' = CN or CO(2)Me) using amine borane adducts RR'NH-BH(3) (R = R' = H, AB; R = Me, R' = H, MAB; R = (t)Bu, R' = H, tBAB; R = R' = Me, DMAB) as hydrogen donors, were studied by means of in situ NMR spectroscopy. Deuterium kinetic isotope effects and the traced hydroboration intermediate revealed that the double H transfer process occurred regio-specifically in two steps with hydride before proton transfer characteristics. Studies on substituent effects and Hammett correlation indicated that the rate determining step of the H(N) transfer is in agreement with a concerted transition state. The very reactive intermediate [NH(2)=BH(2)] generated from AB was trapped by addition of cyclohexene into the reaction mixture forming Cy(2)BNH(2). The final product borazine (BHNH)(3) is assumed to be formed by dehydrocoupling of [NH(2)=BH(2)] or its solvent stabilized derivative [NH(2)=BH(2)]-(solvent), rather than by dehydrogenation of cyclotriborazane (BH(2)NH(2))(3) which is the trimerization product of [NH(2)=BH(2)]. PMID:22124505

  7. Polar Markings

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02155 Polar Markings

    These bright and dark markings occurred near the end of summer in the south polar region. The dark material is likely dust that has been freed of frost cover.

    Image information: VIS instrument. Latitude -76.3N, Longitude 84.9E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  8. Polar Layers

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02153 Polar Layers

    This image of the south polar region shows layered material. It is not known if the layers are formed yearly or if they form over the period of 10s to 100s of years or more.

    Image information: VIS instrument. Latitude -80.3N, Longitude 296.2E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  9. Polar Ridges

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03662 Polar Ridges

    This ridge system is located in the south polar region.

    Image information: VIS instrument. Latitude -81.7N, Longitude 296.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  10. Polar Textures

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03638 Polar Textures

    This image illustrates the variety of textures that appear in the south polar region during late summer.

    Image information: VIS instrument. Latitude 80.5S, Longitude 57.9E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  11. Polar Terrains

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03577 Polar Terrains

    The region surrounding the South Polar Cap contains many different terrain types. This image shows both etched terrain and a region of 'mounds'.

    Image information: VIS instrument. Latitude 75S, Longitude 286.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. A nuclear ribosomal DNA pseudogene in triatomines opens a new research field of fundamental and applied implications in Chagas disease

    PubMed Central

    Zuriaga, María Angeles; Mas-Coma, Santiago; Bargues, María Dolores

    2015-01-01

    A pseudogene, designated as "ps(5.8S+ITS-2)", paralogous to the 5.8S gene and internal transcribed spacer (ITS)-2 of the nuclear ribosomal DNA (rDNA), has been recently found in many triatomine species distributed throughout North America, Central America and northern South America. Among characteristics used as criteria for pseudogene verification, secondary structures and free energy are highlighted, showing a lower fit between minimum free energy, partition function and centroid structures, although in given cases the fit only appeared to be slightly lower. The unique characteristics of "ps(5.8S+ITS-2)" as a processed or retrotransposed pseudogenic unit of the ghost type are reviewed, with emphasis on its potential functionality compared to the functionality of genes and spacers of the normal rDNA operon. Besides the technical problem of the risk for erroneous sequence results, the usefulness of "ps(5.8S+ITS-2)" for specimen classification, phylogenetic analyses and systematic/taxonomic studies should be highlighted, based on consistence and retention index values, which in pseudogenic sequence trees were higher than in functional sequence trees. Additionally, intraindividual, interpopulational and interspecific differences in pseudogene amount and the fact that it is a pseudogene in the nuclear rDNA suggests a potential relationships with fitness, behaviour and adaptability of triatomine vectors and consequently its potential utility in Chagas disease epidemiology and control. PMID:25760450

  13. Nuclear cardiology and CVD in the developing world: Are we applying our scarce resources appropriately? Why is our mortality rate so high?

    PubMed

    Vitola, João V

    2016-10-01

    While mortality rates from cardiovascular diseases have progressively decreased in developed nations, this has not been observed to the same extent in the developing world. Nuclear Cardiology utilization remains low or non-existent for most of those living in the low-to-middle-income countries. How much of the decline in mortality observed in the developed world has to do with advanced cardiac imaging? Are we applying our scarce resources appropriately for myocardial perfusion imaging? Are myocardial revascularizations being guided by appropriate use criteria? Is more imaging necessary to reduce the mortality rates further in the developing world?

  14. Polarized neutrons and their applications

    SciTech Connect

    Moon, R.; Endoh, Y.; Felcher, G.; Majkrzak, C.; Mezei, F.; Pynn, R.; Shirane, G.

    1985-01-01

    The role of polarized neutrons in the study of magnetic and nonmagnetic materials is discussed. magnetic structure, spin density, nuclear magnetism and spin dynamics are listed as magnetic properties which may be accessed by polarized neutrons. Low dimensional magnets, disordered magnetic systems, surface magnetism are discussed as well as topography and depolarization. Polarization techniques are discussed for both study state and pulsed modes. 4 refs. (WRF)

  15. Characterization of high-tannin fractions from humus by carbon-13 cross-polarization and magic-angle spinning nuclear magnetic resonance.

    PubMed

    Lorenz, Klaus; Preston, Caroline M

    2002-01-01

    Condensed tannins can be found in various parts of many plants. Unlike lignin there has been little study of their fate as they enter the soil organic matter pool and their influence on nutrient cycling, especially through their protein-binding properties. We extracted and characterized tannin-rich fractions from humus collected in 1998 from a black spruce [Picea mariana (Mill.) Britton et al.] forest in Canada where a previous study (1995) showed high levels (3.8% by weight) of condensed tannins. A reference tannin purified from black spruce needles was characterized by solution 13C nuclear magnetic resonance (NMR) as a pure procyanidin with mainly cis stereochemistry and an average chain length of four to five units. The colorimetric proanthocyanidin (PA) assay, standardized against the black spruce tannin, showed that both extracted humus fractions had higher tannin contents than the original humus (2.84% and 11.17% vs. 0.08%), and accounted for 32% of humus tannin content. Consistent with the results from the chemical assay, the aqueous fraction showed higher tannin signals in the 13C cross-polarization and magic-angle spinning (CPMAS) NMR spectrum than the emulsified one. As both tannin-rich humus fractions were depleted in N and high in structures derived from lignin and cutin, they did not have properties consistent with recaldtrant tannin-protein complexes proposed as a mechanism for N sequestration in humus. Further studies are needed to establish if tannin-protein structures in humus can be detected or isolated, or if tannins contribute to forest management problems observed in these ecosystems by binding to and slowing down the activity of soil enzymes.

  16. Selective Imaging of Malignant Ascites in a Mouse Model of Peritoneal Metastasis Using in Vivo Dynamic Nuclear Polarization-Magnetic Resonance Imaging.

    PubMed

    Eto, Hinako; Hyodo, Fuminori; Nakano, Kenji; Utsumi, Hideo

    2016-02-16

    The presence of malignant ascites in advanced cancer patients is associated with both a poor prognosis and quality of life with a risk of abdominal infection and sepsis. Contemporary noninvasive visualization methods such as ultrasound, computed tomography, and magnetic resonance imaging (MRI) often struggle to differentiate malignant ascites from surrounding tissues. This study aimed to determine the utility of selective H2O imaging in the abdominal cavity with a free radical probe and deuterium oxide (D2O) contrast agent using in vivo dynamic nuclear polarization-MRI (DNP-MRI). Phantom imaging experiments established a linear relationship between H2O volume and image intensity using in vivo DNP-MRI. Similar results were obtained when the radical-D2O probe was used to determine selective and spatial information on H2O in vivo, modeled by the injection of saline into the abdominal cavity of mice. To demonstrate the utility of this method for disease, malignant ascites in peritoneal metastasis animal model was selected as one of the typical examples. In vivo DNP-MRI of peritoneal metastasis animal model was performed 7-21 days after intraperitoneal injection of luciferase, stably expressing the human pancreatic carcinoma (SUIT-2). The image intensity with increasing malignant ascites was significantly increased at days 7, 16, and 21. This increase corresponded to in vivo tumor progression, as measured by bioluminescent imaging. These results suggest that H2O signal enhancement in DNP-MRI using radical-D2O contrast is positively associated with the progression of dissemination and could be a useful biomarker for malignant ascites with cancer metastasis.

  17. Relativistic effects on the nuclear magnetic shieldings of rare-gas atoms and halogen in hydrogen halides within relativistic polarization propagator theory

    NASA Astrophysics Data System (ADS)

    Gomez, Sergio S.; Maldonado, Alejandro; Aucar, Gustavo A.

    2005-12-01

    In this work an analysis of the electronic origin of relativistic effects on the isotropic dia- and paramagnetic contributions to the nuclear magnetic shielding σ(X ) for noble gases and heavy atoms of hydrogen halides is presented. All results were obtained within the 4-component polarization propagator formalism at different level of approach [random-phase approximation (RPA) and pure zeroth-order approximation (PZOA)], by using a local version of the DIRAC code. From the fact that calculations of diamagnetic contributions to σ within RPA and PZOA approaches for HX(X =Br,I,At) and rare-gas atoms are quite close each to other and the finding that the diamagnetic part of the principal propagator at the PZOA level can be developed as a series [S(Δ)], it was found that there is a branch of negative-energy "virtual" excitations that contribute with more than 98% of the total diamagnetic value even for the heavier elements, namely, Xe, Rn, I, and At. It contains virtual negative-energy molecular-orbital states with energies between -2mc2 and -4mc2. This fact can explain the excellent performance of the linear response elimination of small component (LR-ESC) scheme for elements up to the fifth row in the Periodic Table. An analysis of the convergency of S(Δ ) and its physical implications is given. It is also shown that the total contribution to relativistic effects of the innermost orbital (1s1/2) is by far the largest. For the paramagnetic contributions results at the RPA and PZOA approximations are similar only for rare-gas atoms. On the other hand, if the mass-correction contributions to σp are expressed in terms of atomic orbitals, a different pattern is found for 1s1/2 orbital contributions compared with all other s-type orbitals when the whole set of rare-gas atoms is considered.

  18. A parallel multi-domain solution methodology applied to nonlinear thermal transport problems in nuclear fuel pins

    SciTech Connect

    Philip, Bobby; Berrill, Mark A.; Allu, Srikanth; Hamilton, Steven P.; Sampath, Rahul S.; Clarno, Kevin T.; Dilts, Gary A.

    2015-01-26

    We describe an efficient and nonlinearly consistent parallel solution methodology for solving coupled nonlinear thermal transport problems that occur in nuclear reactor applications over hundreds of individual 3D physical subdomains. Efficiency is obtained by leveraging knowledge of the physical domains, the physics on individual domains, and the couplings between them for preconditioning within a Jacobian Free Newton Krylov method. Details of the computational infrastructure that enabled this work, namely the open source Advanced Multi-Physics (AMP) package developed by the authors are described. The details of verification and validation experiments, and parallel performance analysis in weak and strong scaling studies demonstrating the achieved efficiency of the algorithm are presented. Moreover, numerical experiments demonstrate that the preconditioner developed is independent of the number of fuel subdomains in a fuel rod, which is particularly important when simulating different types of fuel rods. Finally, we demonstrate the power of the coupling methodology by considering problems with couplings between surface and volume physics and coupling of nonlinear thermal transport in fuel rods to an external radiation transport code.

  19. A parallel multi-domain solution methodology applied to nonlinear thermal transport problems in nuclear fuel pins

    DOE PAGES

    Philip, Bobby; Berrill, Mark A.; Allu, Srikanth; Hamilton, Steven P.; Sampath, Rahul S.; Clarno, Kevin T.; Dilts, Gary A.

    2015-01-26

    We describe an efficient and nonlinearly consistent parallel solution methodology for solving coupled nonlinear thermal transport problems that occur in nuclear reactor applications over hundreds of individual 3D physical subdomains. Efficiency is obtained by leveraging knowledge of the physical domains, the physics on individual domains, and the couplings between them for preconditioning within a Jacobian Free Newton Krylov method. Details of the computational infrastructure that enabled this work, namely the open source Advanced Multi-Physics (AMP) package developed by the authors are described. The details of verification and validation experiments, and parallel performance analysis in weak and strong scaling studies demonstratingmore » the achieved efficiency of the algorithm are presented. Moreover, numerical experiments demonstrate that the preconditioner developed is independent of the number of fuel subdomains in a fuel rod, which is particularly important when simulating different types of fuel rods. Finally, we demonstrate the power of the coupling methodology by considering problems with couplings between surface and volume physics and coupling of nonlinear thermal transport in fuel rods to an external radiation transport code.« less

  20. A new combined nuclear magnetic resonance and Raman spectroscopic probe applied to in situ investigations of catalysts and catalytic processes

    SciTech Connect

    Camp, Jules C. J.; Mantle, Michael D.; York, Andrew P. E.; McGregor, James

    2014-06-15

    Both Raman and nuclear magnetic resonance (NMR) spectroscopies are valuable analytical techniques capable of providing mechanistic information and thereby providing insights into chemical processes, including catalytic reactions. Since both techniques are chemically sensitive, they yield not only structural information but also quantitative analysis. In this work, for the first time, the combination of the two techniques in a single experimental apparatus is reported. This entailed the design of a new experimental probe capable of recording simultaneous measurements on the same sample and/or system of interest. The individual datasets acquired by each spectroscopic method are compared to their unmodified, stand-alone equivalents on a single sample as a means to benchmark this novel piece of equipment. The application towards monitoring reaction progress is demonstrated through the evolution of the homogeneous catalysed metathesis of 1‑hexene, with both experimental techniques able to detect reactant consumption and product evolution. This is extended by inclusion of magic angle spinning (MAS) NMR capabilities with a custom made MAS 7 mm rotor capable of spinning speeds up to 1600 Hz, quantified by analysis of the spinning sidebands of a sample of KBr. The value of this is demonstrated through an application involving heterogeneous catalysis, namely the metathesis of 2-pentene and ethene. This provides the added benefit of being able to monitor both the reaction progress (by NMR spectroscopy) and also the structure of the catalyst (by Raman spectroscopy) on the very same sample, facilitating the development of structure-performance relationships.

  1. A Parallel Multi-Domain Solution Methodology Applied to Nonlinear Thermal Transport Problems in Nuclear Fuel Pins

    SciTech Connect

    Philip, Bobby; Berrill, Mark A; Allu, Srikanth; Hamilton, Steven P; Clarno, Kevin T; Dilts, Gary

    2014-08-01

    This paper describes an efficient and nonlinearly consistent parallel solution methodology for solving coupled nonlinear thermal transport problems that occur in nuclear reactor applications over hundreds of individual 3D physical subdomains. Efficiency is obtained by leveraging knowledge of the physical domains, the physics on individual domains, and the couplings between them for preconditioning within a Jacobian Free Newton Krylov method. Details of the computational infrastructure that enabled this work, namely the open source Advanced Multi-Physics (AMP) package developed by the authors is described. Details of verification and validation experiments, and parallel performance analysis in weak and strong scaling studies demonstrating the achieved efficiency of the algorithm are presented. Furthermore, numerical experiments demonstrate that the preconditioner developed is independent of the number of fuel subdomains in a fuel rod, which is particularly important when simulating different types of fuel rods. Finally, we demonstrate the power of the coupling methodology by considering problems with couplings between surface and volume physics and coupling of nonlinear thermal transport in fuel rods to an external radiation transport code.

  2. A new combined nuclear magnetic resonance and Raman spectroscopic probe applied to in situ investigations of catalysts and catalytic processes.

    PubMed

    Camp, Jules C J; Mantle, Michael D; York, Andrew P E; McGregor, James

    2014-06-01

    Both Raman and nuclear magnetic resonance (NMR) spectroscopies are valuable analytical techniques capable of providing mechanistic information and thereby providing insights into chemical processes, including catalytic reactions. Since both techniques are chemically sensitive, they yield not only structural information but also quantitative analysis. In this work, for the first time, the combination of the two techniques in a single experimental apparatus is reported. This entailed the design of a new experimental probe capable of recording simultaneous measurements on the same sample and/or system of interest. The individual datasets acquired by each spectroscopic method are compared to their unmodified, stand-alone equivalents on a single sample as a means to benchmark this novel piece of equipment. The application towards monitoring reaction progress is demonstrated through the evolution of the homogeneous catalysed metathesis of 1‑hexene, with both experimental techniques able to detect reactant consumption and product evolution. This is extended by inclusion of magic angle spinning (MAS) NMR capabilities with a custom made MAS 7 mm rotor capable of spinning speeds up to 1600 Hz, quantified by analysis of the spinning sidebands of a sample of KBr. The value of this is demonstrated through an application involving heterogeneous catalysis, namely the metathesis of 2-pentene and ethene. This provides the added benefit of being able to monitor both the reaction progress (by NMR spectroscopy) and also the structure of the catalyst (by Raman spectroscopy) on the very same sample, facilitating the development of structure-performance relationships.

  3. A parallel multi-domain solution methodology applied to nonlinear thermal transport problems in nuclear fuel pins

    NASA Astrophysics Data System (ADS)

    Philip, Bobby; Berrill, Mark A.; Allu, Srikanth; Hamilton, Steven P.; Sampath, Rahul S.; Clarno, Kevin T.; Dilts, Gary A.

    2015-04-01

    This paper describes an efficient and nonlinearly consistent parallel solution methodology for solving coupled nonlinear thermal transport problems that occur in nuclear reactor applications over hundreds of individual 3D physical subdomains. Efficiency is obtained by leveraging knowledge of the physical domains, the physics on individual domains, and the couplings between them for preconditioning within a Jacobian Free Newton Krylov method. Details of the computational infrastructure that enabled this work, namely the open source Advanced Multi-Physics (AMP) package developed by the authors is described. Details of verification and validation experiments, and parallel performance analysis in weak and strong scaling studies demonstrating the achieved efficiency of the algorithm are presented. Furthermore, numerical experiments demonstrate that the preconditioner developed is independent of the number of fuel subdomains in a fuel rod, which is particularly important when simulating different types of fuel rods. Finally, we demonstrate the power of the coupling methodology by considering problems with couplings between surface and volume physics and coupling of nonlinear thermal transport in fuel rods to an external radiation transport code.

  4. Room temperature hyperpolarization of nuclear spins in bulk

    PubMed Central

    Tateishi, Kenichiro; Negoro, Makoto; Nishida, Shinsuke; Kagawa, Akinori; Morita, Yasushi; Kitagawa, Masahiro

    2014-01-01

    Dynamic nuclear polarization (DNP), a means of transferring spin polarization from electrons to nuclei, can enhance the nuclear spin polarization (hence the NMR sensitivity) in bulk materials at most 660 times for 1H spins, using electron spins in thermal equilibrium as polarizing agents. By using electron spins in photo-excited triplet states instead, DNP can overcome the above limit. We demonstrate a 1H spin polarization of 34%, which gives an enhancement factor of 250,000 in 0.40 T, while maintaining a bulk sample (∼0.6 mg, ∼0.7 × 0.7 × 1 mm3) containing >1019 1H spins at room temperature. Room temperature hyperpolarization achieved with DNP using photo-excited triplet electrons has potentials to be applied to a wide range of fields, including NMR spectroscopy and MRI as well as fundamental physics. PMID:24821773

  5. Polar Layers

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03581 Polar Layers

    This image shows just one example of the bright and dark markings that appear during summer time. The marks are related to the polar layers. If you happen to see a wild-eyed guy sticking his tongue out at you, you'll know why this image qualifies for the old 'art' category of THEMIS releases.

    Image information: VIS instrument. Latitude 80.6S, Longitude 34.1E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  6. Numerical analysis of residual stresses in preforms of stress applying part for PANDA-type polarization maintaining optical fibers in view of technological imperfections of the doped zone geometry

    NASA Astrophysics Data System (ADS)

    Trufanov, Aleksandr N.; Trufanov, Nikolay A.; Semenov, Nikita V.

    2016-09-01

    The experimental data analysis of the stress applying rod section geometry for the PANDA-type polarization maintaining optical fiber has been performed. The dependencies of the change in the radial dimensions of the preform and the doping boundary on the angular coordinate have been obtained. The original algorithm of experimental data statistic analysis, which enables determination of the specimens' characteristic form of section, has been described. The influence of actual doped zone geometry on the residual stress fields formed during the stress rod preform fabrication has been investigated. It has been established that the deviation of the boundary between pure silica and the doped zone from the circular shape results in dissymmetry and local concentrations of the residual stress fields along the section, which can cause preforms destruction at high degrees of doping. The observed geometry deviations of up to 10% lead to the increase of the maximum stress intensity value by over 20%.

  7. Strong pulsed excitations using circularly polarized fields for ultra-low field NMR

    NASA Astrophysics Data System (ADS)

    Shim, Jeong Hyun; Lee, Seong-Joo; Yu, Kwon-Kyu; Hwang, Seong-Min; Kim, Kiwoong

    2014-02-01

    A pulse, which is produced by a single coil and thereby has a linear polarization, cannot coherently drive nuclear spins if the pulse is stronger than the static field B0. The inaccuracy of the pulse, which arises from the failure of the rotating wave approximation, has been an obstacle in adopting multiple pulse techniques in ultra-low field NMR where B0 is less than a few μT. Here, we show that such a limitation can be overcome by applying pulses of circular polarization using two orthogonal coils. The sinusoidal nutation of the nuclear spins was experimentally obtained, which indicates that coherent and precise controls of the nuclear spins can be achieved with circularly polarized pulses. Additional demonstration of the Carl-Purcell-Meiboom-Gill sequence verifies the feasibility of adopting multiple pulse sequences to ultra-low field NMR studies.

  8. Spatial image compounding applied to a phase coherence corrected UT-PA technique for inspecting nuclear components of coarse-grained structure

    NASA Astrophysics Data System (ADS)

    Brizuela, Jose; Katchadjian, Pablo; Garcia, Alejandro; Desimone, Carlos

    2016-02-01

    The aim of this work is to obtain a C-Scan view of an austenitic stainless steel weld from a nuclear use pipe. In order to obtain this result Sectorial Scans (S-Scan) from both sides of the weld are obtained by Ultrasonic Phase Array (UT-PA). Then, spatial image compounding is performed to generate a single image from the S-Scans acquired at the same circumferential position of the transducer. These joints have a coarse grain structure which significantly reduce the transmission of the ultrasonic wave due to attenuation characteristics and backscattered noise from microstructures inside the material. For this reason, phase coherence imaging technique has been also applied to reduce the structural noise and improve the image quality. To verify detected defects, and given the impossibility of cutting the component, gammagraphy were performed with Co60.

  9. Laboratory Search for a Long-Range T-Odd, P-Odd Interaction from Axionlike Particles Using Dual-Species Nuclear Magnetic Resonance with Polarized Xe129 and Xe131 Gas

    NASA Astrophysics Data System (ADS)

    Bulatowicz, M.; Griffith, R.; Larsen, M.; Mirijanian, J.; Fu, C. B.; Smith, E.; Snow, W. M.; Yan, H.; Walker, T. G.

    2013-09-01

    Various theories beyond the standard model predict new particles with masses in the sub-eV range with very weak couplings to ordinary matter. A new P-odd and T-odd interaction between polarized and unpolarized nucleons proportional to K→·r→ is one such possibility, where r→ is the distance between the nucleons and K→ is the spin of the polarized nucleon. Such an interaction involving a scalar coupling gs at one vertex and a pseudoscalar coupling gp at the polarized nucleon vertex can be induced by the exchange of spin-0 bosons. We used the NMR cell test station at Northrop Grumman Corporation to search for NMR frequency shifts in polarized Xe129 and Xe131 when a nonmagnetic zirconia rod is moved near the NMR cell. Long (T2˜20s) spin-relaxation times allow precision measurements of the NMR frequency ratios, which are insensitive to magnetic field fluctuations. Combined with existing theoretical calculations of the neutron spin contribution to the nuclear angular momentum in xenon nuclei, the measurements improve the laboratory upper bound on the product gsgpn by 2 orders of magnitude for distances near 1 mm. The sensitivity of this technique can be increased by at least two more orders of magnitude.

  10. Laboratory search for a long-range T-odd, P-odd interaction from axionlike particles using dual-species nuclear magnetic resonance with polarized 129Xe and 131Xe gas.

    PubMed

    Bulatowicz, M; Griffith, R; Larsen, M; Mirijanian, J; Fu, C B; Smith, E; Snow, W M; Yan, H; Walker, T G

    2013-09-01

    Various theories beyond the standard model predict new particles with masses in the sub-eV range with very weak couplings to ordinary matter. A new P-odd and T-odd interaction between polarized and unpolarized nucleons proportional to K·r is one such possibility, where r is the distance between the nucleons and K is the spin of the polarized nucleon. Such an interaction involving a scalar coupling gs at one vertex and a pseudoscalar coupling gp at the polarized nucleon vertex can be induced by the exchange of spin-0 bosons. We used the NMR cell test station at Northrop Grumman Corporation to search for NMR frequency shifts in polarized 129Xe and 131Xe when a nonmagnetic zirconia rod is moved near the NMR cell. Long (T2∼20  s) spin-relaxation times allow precision measurements of the NMR frequency ratios, which are insensitive to magnetic field fluctuations. Combined with existing theoretical calculations of the neutron spin contribution to the nuclear angular momentum in xenon nuclei, the measurements improve the laboratory upper bound on the product gsgp(n) by 2 orders of magnitude for distances near 1 mm. The sensitivity of this technique can be increased by at least two more orders of magnitude.

  11. Polarization developments

    SciTech Connect

    Prescott, C.Y.

    1993-07-01

    Recent developments in laser-driven photoemission sources of polarized electrons have made prospects for highly polarized electron beams in a future linear collider very promising. This talk discusses the experiences with the SLC polarized electron source, the recent progress with research into gallium arsenide and strained gallium arsenide as a photocathode material, and the suitability of these cathode materials for a future linear collider based on the parameters of the several linear collider designs that exist.

  12. Neuronal polarization.

    PubMed

    Takano, Tetsuya; Xu, Chundi; Funahashi, Yasuhiro; Namba, Takashi; Kaibuchi, Kozo

    2015-06-15

    Neurons are highly polarized cells with structurally and functionally distinct processes called axons and dendrites. This polarization underlies the directional flow of information in the central nervous system, so the establishment and maintenance of neuronal polarization is crucial for correct development and function. Great progress in our understanding of how neurons establish their polarity has been made through the use of cultured hippocampal neurons, while recent technological advances have enabled in vivo analysis of axon specification and elongation. This short review and accompanying poster highlight recent advances in this fascinating field, with an emphasis on the signaling mechanisms underlying axon and dendrite specification in vitro and in vivo.

  13. Investigation of laser polarized xenon magnetic resonance

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    1998-01-01

    Ground-based investigations of a new biomedical diagnostic technology: nuclear magnetic resonance of laser polarized noble gas are addressed. The specific research tasks discussed are: (1) Development of a large-scale noble gas polarization system; (2) biomedical investigations using laser polarized noble gas in conventional (high magnetic field) NMR systems; and (3) the development and application of a low magnetic field system for laser polarized noble gas NMR.

  14. Exploring the conformational energy landscape of glassy disaccharides by cross polarization magic angle spinning 13C nuclear magnetic resonance and numerical simulations. II. Enhanced molecular flexibility in amorphous trehalose.

    PubMed

    Lefort, Ronan; Bordat, Patrice; Cesaro, Attilio; Descamps, Marc

    2007-01-01

    This paper uses chemical shift surfaces to simulate experimental (13)C cross polarization magic angle spinning spectra for amorphous solid state disaccharides, paying particular attention to the glycosidic linkage atoms in trehalose, sucrose, and lactose. The combination of molecular mechanics with density functional theory/gauge invariant atomic orbital ab initio methods provides reliable structural information on the conformational distribution in the glass. The results are interpreted in terms of an enhanced flexibility that trehalose possesses in the amorphous solid state, at least on the time scale of (13)C nuclear magnetic resonance measurements. Implications of these findings for the fragility of trehalose glass and bioprotectant action are discussed. PMID:17212504

  15. Exploring the conformational energy landscape of glassy disaccharides by cross polarization magic angle spinning 13C nuclear magnetic resonance and numerical simulations. II. Enhanced molecular flexibility in amorphous trehalose

    NASA Astrophysics Data System (ADS)

    Lefort, Ronan; Bordat, Patrice; Cesaro, Attilio; Descamps, Marc

    2007-01-01

    This paper uses chemical shift surfaces to simulate experimental C13 cross polarization magic angle spinning spectra for amorphous solid state disaccharides, paying particular attention to the glycosidic linkage atoms in trehalose, sucrose, and lactose. The combination of molecular mechanics with density functional theory/gauge invariant atomic orbital ab initio methods provides reliable structural information on the conformational distribution in the glass. The results are interpreted in terms of an enhanced flexibility that trehalose possesses in the amorphous solid state, at least on the time scale of C13 nuclear magnetic resonance measurements. Implications of these findings for the fragility of trehalose glass and bioprotectant action are discussed.

  16. Polar Bear

    USGS Publications Warehouse

    Amstrup, S.D.; ,; Lentfer, J.W.

    1988-01-01

    Polar bears are long-lived, late-maturing carnivores that have relatively low rates of reproduction and natural mortality. Their populations are susceptible to disturbance from human activities, such as the exploration and development of mineral resources or hunting. Polar bear populations have been an important renewable resource available to coastal communities throughout the Arctic for thousands of years.

  17. Polarized rainbow.

    PubMed

    Können, G P; de Boer, J H

    1979-06-15

    The Airy theory of the rainbow is extended to polarized light. For both polarization directions a simple analytic expression is obtained for the intensity distribution as a function of the scattering angle in terms of the Airy function and its derivative. This approach is valid at least down to droplet diameters of 0.3 mm in visible light. The degree of polarization of the rainbow is less than expected from geometrical optics; it increases with droplet size. For a droplet diameter >1 mm the locations of the supernumerary rainbows are equal for both polarization directions, but for a diameter <1 mm the supernumerary rainbows of the weaker polarization component are located between those in the strong component. PMID:20212586

  18. Sensitivity of VIIRS Polarization Measurements

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene

    2010-01-01

    The design of an optical system typically involves a sensitivity analysis where the various lens parameters, such as lens spacing and curvatures, to name two parameters, are (slightly) varied to see what, if any, effect this has on the performance and to establish manufacturing tolerances. A sinular analysis was performed for the VIIRS instruments polarization measurements to see how real world departures from perfectly linearly polarized light entering VIIRS effects the polarization measurement. The methodology and a few of the results of this polarization sensitivity analysis are presented and applied to the construction of a single polarizer which will cover the VIIRS VIS/NIR spectral range. Keywords: VIIRS, polarization, ray, trace; polarizers, Bolder Vision, MOXTEK

  19. An electromagnetic helical undulator for polarized x-rays

    SciTech Connect

    Gluskin, E.; Vinokurov, N.; Tcheskidov, V.; Medvedko, A.; Evtushenko, Y. Kolomogorov, V.; Vobly, P.; Antokhin, E.; Ivanov, P.; Vasserman, I. B.; Trakhtenberg, E. M.; Den Hartog, P. K.; Deriy, B.; Erdmann, M.; Makarov, O.; Moog, E. R.

    1999-10-28

    Linearly and circularly polarized x-rays have been very successfully applied to the study of the properties of materials. Many applications can benefit from the availability of energy-turnable, high-brilliance x-ray beams with adjustable polarization properties. A helical undulator that can generate beams of variable (linear to circular) polarization has been designed and built by the Budker Institute of Nuclear Physics and the Advanced Photon Source. The first harmonic of this 12.8-cm-period device will cover the energy range from 0.4 keV to 3.5 keV. An important feature of this fully electromagnetic device is that it will allow one to generate 100% horizontally (K{sub x}=O)or vertically (K{sub y}=O) plane-polarized radiation, which will enable many experiments otherwise not technically feasible. With symmetric deflection parameters (K{sub x}=K{sub y}), the on-axis radiation will be circularly polarized, with a user-selectable handedness. The polarization can be changed at rates up to 10 Hz.

  20. Polarizing cues.

    PubMed

    Nicholson, Stephen P

    2012-01-01

    People categorize themselves and others, creating ingroup and outgroup distinctions. In American politics, parties constitute the in- and outgroups, and party leaders hold sway in articulating party positions. A party leader's endorsement of a policy can be persuasive, inducing co-partisans to take the same position. In contrast, a party leader's endorsement may polarize opinion, inducing out-party identifiers to take a contrary position. Using survey experiments from the 2008 presidential election, I examine whether in- and out-party candidate cues—John McCain and Barack Obama—affected partisan opinion. The results indicate that in-party leader cues do not persuade but that out-party leader cues polarize. This finding holds in an experiment featuring President Bush in which his endorsement did not persuade Republicans but it polarized Democrats. Lastly, I compare the effect of party leader cues to party label cues. The results suggest that politicians, not parties, function as polarizing cues. PMID:22400143

  1. Tilted foils polarization at REX-ISOLDE

    NASA Astrophysics Data System (ADS)

    Törnqvist, H.; Sotty, C.; Balabanski, D.; Dhal, A.; Georgiev, G.; Hass, M.; Heinz, A.; Hirayama, Y.; Imai, N.; Johansson, H.; Kowalska, M.; Kusoglu, A.; Nilsson, T.; Stuchbery, A.; Wenander, F.; Yordanov, D. T.

    2013-12-01

    The tilted-foils nuclear-spin polarization method has been evaluated using the REX-ISOLDE linear accelerator at the ISOLDE facility, CERN. A beam of 8Li delivered with an energy of 300 keV/u traversed through one Mylar foil to degrade the beam energy to 200 keV/u and consequently through 10 thin diamond-like carbon foils to polarize the nuclear spin. The attained nuclear spin polarization of 3.6±0.3% was measured with a β-NMR setup.

  2. EDITORIAL: Polarization Optics

    NASA Astrophysics Data System (ADS)

    Turunen, Jari; Friesem, Asher A.; Friberg, Ari T.

    2004-03-01

    transmission of intense light enable research into the chirality of nanogratings. Pump-probe techniques allow one to visualize the effects of the nanostructure topology on the surface mode excitation. In quantum optics the coherent control of polarization may lead to new and fascinating applications. Some authors of invited papers at the conference have written review-type introductory sections—they were encouraged to do so—but all contributions are genuine research papers with original results, and were judged according to the normal publication criteria of the journal. It is our pleasure to thank all authors for making this a splendid special issue of Journal of Optics A: Pure and Applied Optics.

  3. Overcoming Polarization Aberrations In Microscopy

    NASA Astrophysics Data System (ADS)

    Hansen, Eric W.

    1988-06-01

    A long-standing problem in polarized light microscopy has been the inability, due to polarization aberrations, to achieve simultaneously high spatial resolution and high contrast. The rotation of the plane of polarization at oblique interfaces between crossed polars causes the pupil function to resemble a dark cross rather than being uniformly dark. Likewise, the point spread function has the visual appearance of a four-leaf clover rather than the ideal Airy disk, and is also space-variant. Images formed with these systems are severely degraded. In this paper the theory of polarization aberrations is applied to the analysis of three solutions to this problem: Reducing the system aperture to block troublesome high-aperture rays; the AVEC-POL method, in which high bias compensation introduces counterbalancing aberrations; and the polarization rectifier, an optical element designed to introduce equal and opposite rotations of the electric vector.

  4. Polar Color

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 3 May 2004 This nighttime visible color image was collected on January 1, 2003 during the Northern Summer season near the North Polar Troughs.

    This daytime visible color image was collected on September 4, 2002 during the Northern Spring season in Vastitas Borealis. The THEMIS VIS camera is capable of capturing color images of the martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    Image information: VIS instrument. Latitude 79, Longitude 346 East (14 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with

  5. Voltage control of electron-nuclear spin correlation time in a single quantum dot

    NASA Astrophysics Data System (ADS)

    Nilsson, J.; Bouet, L.; Bennett, A. J.; Amand, T.; Stevenson, R. M.; Farrer, I.; Ritchie, D. A.; Kunz, S.; Marie, X.; Shields, A. J.; Urbaszek, B.

    2013-08-01

    We demonstrate bias control of the efficiency of the hyperfine coupling between a single electron in an InAs quantum dot and the surrounding nuclear spins monitored through the positively charged exciton X+ emission. In applied longitudinal magnetic fields, we vary simultaneously the correlation time of the hyperfine interaction and the nuclear spin relaxation time and thereby the amplitude of the achieved dynamic nuclear polarization under optical pumping conditions. In applied transverse magnetic fields, a change in the applied bias allows a switch from the anomalous Hanle effect to the standard electron spin depolarization curves.

  6. Error-compensation measurements on polarization qubits

    NASA Astrophysics Data System (ADS)

    Hou, Zhibo; Zhu, Huangjun; Xiang, Guo-Yong; Li, Chuan-Feng; Guo, Guang-Can

    2016-06-01

    Systematic errors are inevitable in most measurements performed in real life because of imperfect measurement devices. Reducing systematic errors is crucial to ensuring the accuracy and reliability of measurement results. To this end, delicate error-compensation design is often necessary in addition to device calibration to reduce the dependence of the systematic error on the imperfection of the devices. The art of error-compensation design is well appreciated in nuclear magnetic resonance system by using composite pulses. In contrast, there are few works on reducing systematic errors in quantum optical systems. Here we propose an error-compensation design to reduce the systematic error in projective measurements on a polarization qubit. It can reduce the systematic error to the second order of the phase errors of both the half-wave plate (HWP) and the quarter-wave plate (QWP) as well as the angle error of the HWP. This technique is then applied to experiments on quantum state tomography on polarization qubits, leading to a 20-fold reduction in the systematic error. Our study may find applications in high-precision tasks in polarization optics and quantum optics.

  7. Polarization Considerations

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene

    1998-01-01

    As light passes through a optical system the reflections and refractions will in general change the polarization state of the light. If we assume that all of the materials in the thin film coatings and substrate are isotropic and homogeneous then calculating the amount of "instrumental" polarization is a relatively straight forward task. In the following sections we will present a of the steps required to perform a 'polarization ray trace' calculation for a single ray and monochromatic and hence polarized light. The thin film portion of the calculation is also shown. The reason for explicitly showing the thin film equations is that there are sign conventions imposed on the boundary value equations by the orientation and handedness of the various coordinate frames which are attached to the geometric rays. The attenuation of light through a optical system, is relatively simple, and requires at the very least a lens (average) reflectivity or transmissivity. Determining the polarization sensitivity of a optical system is still relatively straight forward requiring at least a knowledge of the behavior of the "s" and "p" components at each interface for the chief ray. Determining the thin film induced aberrations of a optical system are somewhat more demanding. Questions about the arithmetic sign of the phase factors and how this relates to the overall "OPD" of a ray are ubiquitous. Many rays are required to construct a wavefront. Thin film codes which modify the OPD's of rays are a requirement for this last mentioned computation. This requires a consistent scheme of coordinate frames and sign conventions and is probably the most demanding task of a polarization ray trace. Only the electric field will used in the discussion. This is not a restriction as the Stokes parameters are functions of the electric field. The following does not attempt to explain, but only to present all of the required concepts and formulas.

  8. Artificial polarization components

    NASA Astrophysics Data System (ADS)

    Cescato, L.; Gluch, Ekkehard; Stork, Wilhelm; Streibl, Norbert

    1990-07-01

    High frequency surface relief structures are optically anisotropic and show interesting polarisation properties 1 . These properties can be used to produce polarizations components such as wave plates polarizers. polarizing beamsplitters etc. Our experimental results show that even gratings with relatively low spatial frequency ( periods A ) exhibit a strong phase retardation and can be used as quarter-wave plates. k INTRODUC11ON The artificial birefringence exhibited by ultrahigh frequency gratings of dielectric materials can be used to produce various polarization components2 . Such components have applications in integrated optics as well as in free space optics. In order to produce the high spatial frequencies complex processes such as electron-beam lithography and reactive ion etching are needed. We show in this paper that sinusoidal holographic gratings in photoresist exhibit also a strong phase ret even at relatively long periods. L EXPERIMENTAL MEASUREMENTS To obtain the phase retardation of a lower frequency ( period A ) grating a simple setup as used by Enger and 2 can be applied. In our case however there are three measurements necessary to obtain the phase retardation because transmission of the two perpendicularly polarized beams is different from each other. I GRATING PRODUCTION grating 2 3 4 5 6 7 8 9 period (pmj 0. 74 0. 74 0. 61 0. 54 0. 46 0. 32 0. 54 0. 54 0. 54 ne (sec) 60

  9. Observables for polarized neutrons transmitted through polarized targets

    SciTech Connect

    Hnizdo, V. )

    1994-11-01

    A general and concise formalism is presented for the identification and evaluation of observables, including those that would indicate parity-conservation and/or time-reversal violation by the neutron-nucleus interaction, of experiments on the transmission of polarized neutrons through polarized nuclear targets. Statistical tensors are used for the description of the polarization states of the projectile and target, and the neutron-nucleus total cross section is decomposed into partial cross sections so that each corresponds to different ranks of the projectile and target statistical tensors and to a specific transfer of the orbital angular momentum. Each such partial cross section is associated with a correlation factor'' of particular parity-conservation and time-reversal symmetries, and is measurable by polarizing the projectile and target in states in which the statistical tensors have specific geometries, suggested by the simple geometric properties of the correlation factors.

  10. EXFOR Library of Experimental Nuclear Reaction Data

    DOE Data Explorer

    The EXFOR library contains an extensive compilation of experimental nuclear reaction data up to 1 GeV. Neutron reactions have been compiled systematically since the discovery of the neutron, while charged particle(up to carbon) and photon reactions have been covered less extensively. Files contain nuclear reaction data such as cross sections, spectra, angular distributions, polarizations, etc, along with information on experimental technique, error analysis, and applied standards. Numerous search parameters include: target, beam, product, experimental method, and even author and publication names. The library contains data from more than 20,000 experiments. (Specialized Interface)

  11. Application of polarized nuclei to fusion

    SciTech Connect

    Kulsrud, R.M.

    1987-07-01

    It is shown that the d-t fusion reaction can be modified by polarizing nuclear spins. The ways in which this improves reactor performance are mentioned and the feasibility of the process of spin polarization for magnetic fusion is discussed. 18 refs.

  12. Polarization of antiprotons by antiproton decay

    SciTech Connect

    Yokosawa, A.

    1985-01-01

    The production of polarized antiproton beams at Fermilab is briefly reviewed. Two types of high-energy anti p polarimeters are described - the Coulomb-nuclear polarimeter and the Primakoff-effect polarimeter. The production of 8.9 GeV/c polarized antiprotons before entering the Fermilab accumulator ring is then discussed. 5 refs., 6 figs. (LEW)

  13. Nuclear Resonance Vibrational Spectroscopy applied to [Fe(OEP)(NO)]: The Vibrational Assignments of Five-Coordinate Ferrous Heme Nitrosyls and Implications for Electronic Structure

    PubMed Central

    Lehnert, Nicolai; Galinato, Mary Grace I.; Paulat, Florian; Richter-Addo, George B.; Sturhahn, Wolfgang; Xu, Nan; Zhao, Jiyong

    2010-01-01

    This study presents Nuclear Resonance Vibrational Spectroscopy (NRVS) data on the five-coordinate (5C) ferrous heme nitrosyl complex [Fe(OEP)(NO)] (1, OEP2− = octaethylporphyrinato dianion) and the corresponding 15N18O labeled complex. The obtained spectra identify two isotope sensitive features at 522 and 388 cm−1, which shift to 508 and 381 cm−1, respectively, upon isotope labeling. These features are assigned to the Fe-NO stretch ν(Fe-NO) and the in-plane Fe-N-O bending mode δip(Fe-N-O), the latter has been unambiguously assigned for the first time for 1. The obtained NRVS data were simulated using our quantum chemistry centered normal coordinate analysis (QCC-NCA). Since complex 1 can potentially exist in 12 different conformations involving the FeNO and peripheral ethyl orientations, extended DFT calculations and QCC-NCA simulations were performed to determine how these conformations affect the NRVS properties of [Fe(OEP)NO]. These results show that the properties and force constants of the FeNO unit are hardly affected by the conformational changes involving the ethyl substituents. On the other hand, the NRVS-active porphyrin-based vibrations around 340 – 360, 300 –320, and 250 – 270 cm−1 are sensitive to the conformational changes. The spectroscopic changes observed in these regions are due to selective mechanical couplings of one component of Eu-type (in ideal D4h symmetry) porphyrin-based vibrations with the in-plane Fe-N-O bending mode. This leads to the observed variations in Fe(OEP) core mode energies and NRVS intensities without affecting the properties of the FeNO unit. The QCC-NCA simulated NRVS spectra of 1 show excellent agreement with experiment, and indicate that conformer F is likely present in the samples of this complex investigated here. The observed porphyrin-based vibrations in the NRVS spectra of 1 are also assigned based on the QCC-NCA results. The obtained force constants of the Fe-NO and N-O bonds are 2.83 – 2

  14. Cell polarity

    PubMed Central

    Romereim, Sarah M

    2011-01-01

    Despite extensive genetic analysis of the dynamic multi-phase process that transforms a small population of lateral plate mesoderm into the mature limb skeleton, the mechanisms by which signaling pathways regulate cellular behaviors to generate morphogenetic forces are not known. Recently, a series of papers have offered the intriguing possibility that regulated cell polarity fine-tunes the morphogenetic process via orienting cell axes, division planes and cell movements. Wnt5a-mediated non-canonical signaling, which may include planar cell polarity, has emerged as a common thread in the otherwise distinct signaling networks that regulate morphogenesis in each phase of limb development. These findings position the limb as a key model to elucidate how global tissue patterning pathways direct local differences in cell behavior that, in turn, generate growth and form. PMID:22064549

  15. Polar Diving

    NASA Technical Reports Server (NTRS)

    2006-01-01

    3 July 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layers exposed by erosion in a trough within the north polar residual cap of Mars, diving beneath a younger covering of polar materials. The layers have, since the Mariner 9 mission in 1972, been interpreted to be composed of a combination of dust and ice in unknown proportions. In this scene, a layer of solid carbon dioxide, which was deposited during the previous autumn and winter, blankets the trough as well as the adjacent terrain. Throughout northern spring, the carbon dioxide will be removed; by summer, the layers will be frost-free.

    Location near: 81.4oN, 352.2oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Spring

  16. Polar Summer

    NASA Technical Reports Server (NTRS)

    2005-01-01

    30 December 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroding mesas of frozen carbon dioxide in the martian south polar residual cap. During the summer season, the scarps that bound each pit and mesa in the south polar region become dark as carbon dioxide sublimes away. The darkening might result from the roughening of the surfaces from which ice is subliming, or from the concentration of trace amounts of dust on these slopes, or both.

    Location near: 84.7oS, 48.2oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  17. Design of a tensor polarized deuterium target polarized by spin-exchange with optically pumped NA

    SciTech Connect

    Green, M.C.

    1984-05-01

    A proposed design for a tensor polarized deuterium target (approx. 10/sup 15/ atoms/cm/sup 2/) for nuclear physics studies in an electron storage ring accelerator is presented. The deuterium atoms undergo electron spin exchange with a highly polarized sodium vapor; this polarization is transferred to the deuterium nuclei via the hyperfine interaction. The deuterium nuclei obtain their tensor polarization through repeated electron spin exchange/hyperfine interactions. The sodium vapor polarization is maintained by standard optical pumping techniques. Model calculations are presented in detail leading to a discussion of the expected performance and the technical obstacles to be surmounted in the development of such a target. 15 references, 10 figures.

  18. Polar Landforms

    NASA Technical Reports Server (NTRS)

    2005-01-01

    10 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded remnants of carbon dioxide ice in the south polar residual cap of Mars. The scarps that outline each small mesa have retreated about 3 meters (10 feet) per Mars year since MGS began orbiting the red planet in 1997.

    Location near: 87.0oS, 31.9oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  19. Polar Layers

    NASA Technical Reports Server (NTRS)

    2005-01-01

    12 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a slope upon which are exposed some of the layered materials that underlie the south polar cap of Mars. The layers are generally considered to be sediments--perhaps dust--that may have been cemented by water ice.

    Location near: 84.1oS, 343.9oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  20. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    NASA Astrophysics Data System (ADS)

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2011-05-01

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from 235U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 × 10-5. The upper limit for the asymmetry coefficient has been set to | D n | < 6 × 10-5 at 99% confidence level, whereas for ternary fission correlation coefficient D α = (170±20) × 10-5. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5° to the fission axis, the correlation coefficient was found to be (1.57 ± 0.20) × 10-4, while at the angle of 67.5° it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt γ-rays.

  1. Polarization phenomena in projectile fragmentation process

    SciTech Connect

    Matsuta, K.; Ozawa, A.; Nojiri, Y.; Minamisono, T.; Fukuda, M.; Kitagawa, A.; Momota, S.; Ohtsubo, T.; Matsuo, Y.; Takechi, H.; Fukuda, S.; Minami, I.; Sugimoto, K.; Tanihata, I.; Omata, K.; Alonso, J.R.; Krebs, G.F.; Symons, T.J.M.

    1992-03-01

    The nuclear spin polarization of beta-emitting fragments {sup 37}K and {sup 39} Ca has been measured at around the grazing angle of the {sup 40}Ca + Au collision at 106 MeV/u. Momentum dependence of the observed fragment polarization supports the idea that the origin of the polarization is the orbital angular momentum held by the fragment part of the projectile before the collision takes place. The sizable polarization of about 5% that was observed for the fragments will be a powerful tool for NMR study of the fragments.

  2. Applications of highly spin-polarized xenon in NMR

    SciTech Connect

    Long, H.W. |

    1993-09-01

    The main goal of the work presented in this thesis is produce highly spin-polarized xenon to create much greater signal intensities (up to 54,000 times greater) so as to allow studies to be made on systems with low surface area and long spin-lattice relaxation times. The spin-exchange optical pumping technique used to create high nuclear spin polarization is described in detail in chapter two. This technique is initially applied to some multiple-pulse optically detected NMR experiments in low magnetic field (50G) that allow the study of quadrupoler interactions with a surface of only a few square centimeters. In chapter three the apparatus used to allow high field {sup 129}Xe NMR studies to be performed with extremely high sensitivity is described and applied to experiments on diamagnetic susceptibility effects in thin ({approximately}2000 layers) films of frozen xenon. Preliminary surface investigations of laser polarized {sup 129}Xe adsorbed an a variety of materials (salts, molecular crystals, amorphous carbon, graphite) are then discussed. A full detailed study of the surface of a particular polymer, poly(acrylic acid), is presented in chapter four which shows the kind of detailed information that can be obtained from this technique. Along with preliminary results for several similar polymers, a summary is given of xenon studies of a novel ultra-high surface area polymer, poly(triarylcarbinol). Finally in chapter five the exciting possibility of transferring the high spin order of the laser polarized xenon has been used to transfer nuclear spin order to {sup 13}CO{sub 2} in a xenon matrix and to protons on poly(triarylcarbinol).

  3. Polar ozone

    NASA Technical Reports Server (NTRS)

    Solomon, S.; Grose, W. L.; Jones, R. L.; Mccormick, M. P.; Molina, Mario J.; Oneill, A.; Poole, L. R.; Shine, K. P.; Plumb, R. A.; Pope, V.

    1990-01-01

    The observation and interpretation of a large, unexpected ozone depletion over Antarctica has changed the international scientific view of stratospheric chemistry. The observations which show the veracity, seasonal nature, and vertical structure of the Antarctic ozone hole are presented. Evidence for Arctic and midlatitude ozone loss is also discussed. The chemical theory for Antarctic ozone depletion centers around the occurrence of polar stratospheric clouds (PSCs) in Antarctic winter and spring; the climatology and radiative properties of these clouds are presented. Lab studies of the physical properties of PSCs and the chemical processes that subsequently influence ozone depletion are discussed. Observations and interpretation of the chemical composition of the Antarctic stratosphere are described. It is shown that the observed, greatly enhanced abundances of chlorine monoxide in the lower stratosphere are sufficient to explain much if not all of the ozone decrease. The dynamic meteorology of both polar regions is given, interannual and interhemispheric variations in dynamical processes are outlined, and their likely roles in ozone loss are discussed.

  4. Modeling of forming radially polarized beams on the basis of refractive elements with interference polarizer

    NASA Astrophysics Data System (ADS)

    Paranin, Vyacheslav D.; Karpeev, Sergey V.; Khonina, Svetlana N.

    2016-03-01

    The calculation and simulation of interference polarizer to generate radially polarized light is made. The method is based on converting the conical wavefront passing through the interference polarizer. The multilayer optical coating can be applied on the surface of the axicon. It is shown that in this way we noticeably reduce both the operating angle of incidence and achieve practically significant degree of polarization of the beam generated at much lower energy losses.

  5. T-odd angular correlations in the emission of prompt gamma rays and neutrons in nuclear fission induced by polarized neutrons

    SciTech Connect

    Danilyan, G. V.; Klenke, J.; Krakhotin, V. A.; Kopach, Yu. N.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2011-05-15

    Study of the T-odd three-vector correlation in the emission of prompt neutrons from {sup 235}U fission by polarized cold neutrons has been continued at the facility MEPHISTO of the FRM II reactor (Technical University of Munich). The sought correlation was not found within experimental error of 2.3 Multiplication-Sign 10{sup -5}. The upper limit for the asymmetry coefficient has been set to vertical bar D{sub n} vertical bar < 6 Multiplication-Sign 10{sup -5} at 99% confidence level, whereas for ternary fission correlation coefficient D{sub {alpha}} = (170{+-}20) Multiplication-Sign 10{sup -5}. This limit casts doubt on a model that explains the three-vector correlation in ternary fission by the Coriolis mechanism. At the same time, five-vector correlation in the emission of prompt fission neutrons has been measured, which describes the rotation of the fissioning nucleus at the moment it breaks (ROT effect). At the angle 22.5 Degree-Sign to the fission axis, the correlation coefficient was found to be (1.57 {+-} 0.20) Multiplication-Sign 10{sup -4}, while at the angle of 67.5 Degree-Sign it is zero within the experimental uncertainty. The existence of ROT effect in the emission of prompt fission neutrons can be explained by the anisotropy of neutron emission in the rest frame of the fragment (fission fragments are aligned with respect to the axis of deformation of the fissioning nucleus), similar to the mechanism of ROT effect in the emission of prompt {gamma}-rays.

  6. Active polarization coupler for birefringent fiber

    NASA Astrophysics Data System (ADS)

    Brooks, J. L.; Youngquist, R. C.; Kino, G. S.; Shaw, H. J.

    1984-06-01

    Static coupling between polarization modes achieved by periodically stressing birefringent fiber once per beat length was recently reported. The same scheme is now used to obtain coupling modulation at kilohertz-to-megahertz frequencies by applying pressure to the fiber with an oscillating piezoelectric ceramic. An amplitude of 30-50 V (peak to peak) was found to be necessary to modulate the polarization coupling from a minimum to a maximum. Polarization modulation is also achieved by applying stress along one fiber polarization axis between the two static couplers of a Mach-Zehnder interferometer.

  7. Spectral degree of polarization uniformity for polarization-sensitive OCT

    NASA Astrophysics Data System (ADS)

    Baumann, Bernhard; Zotter, Stefan; Pircher, Michael; Götzinger, Erich; Rauscher, Sabine; Glösmann, Martin; Lammer, Jan; Schmidt-Erfurth, Ursula; Gröger, Marion; Hitzenberger, Christoph K.

    2015-12-01

    Depolarization of light can be measured by polarization-sensitive optical coherence tomography (PS-OCT) and has been used to improve tissue discrimination as well as segmentation of pigmented structures. Most approaches to depolarization assessment for PS-OCT - such as the degree of polarization uniformity (DOPU) - rely on measuring the uniformity of polarization states using spatial evaluation kernels. In this article, we present a different approach which exploits the spectral dimension. We introduce the spectral DOPU for the pixelwise analysis of polarization state variations between sub-bands of the broadband light source spectrum. Alongside a comparison with conventional spatial and temporal DOPU algorithms, we demonstrate imaging in the healthy human retina, and apply the technique for contrasting hard exudates in diabetic retinopathy and investigating the pigment epithelium of the rat iris.

  8. Preliminary development of an integrated approach to the evaluation of pressurized thermal shock as applied to the Oconee Unit 1 Nuclear Power Plant

    SciTech Connect

    Burns, T J; Cheverton, R D; Flanagan, G F; White, J D; Ball, D G; Lamonica, L B; Olson, R

    1986-05-01

    An evaluation of the risk to the Oconee-1 nuclear plant due to pressurized thermal shock (PTS) has been Completed by Oak Ridge National Laboratory (ORNL). This evaluaion was part of a Nuclear Regulatory Commission (NRC) program designed to study the PTS risk to three nuclear plants: Oconee-1, a Babcock and Wilco reactor plant owned and operated by Duke Power Company; Calvert Cliffs-1, a Combustion Engineering reactor plant owned and operated by Baltimore Gas and Electric company; and H.B. Robinson-2, a Westinghouse reactor plant owned and operated by Carolina Power and Light Company. Studies of Calvert Cliffs-1 and H.B. Robinson-2 are still underway. The specific objectives of the Oconee-1 study were to: (1) provide a best estimate of the probability of a through-the-wall crack (TWC) occurring in the reactor pressure vessel as a result of PTS; (2) determine dominant accident sequences, plant features, operator and control actions and uncertainty in the PTS risk; and (3) evaluate effectiveness of potential corrective measures.

  9. Polarized light ions and spectator nucleon tagging at EIC

    SciTech Connect

    Guzey, Vadim; Higinbotham, Dougas W.; Hyde, Charles; Nadel-Turonski, Pawel A.; Park, Kijun; Sargsian, Misak M.; Strikman, Mark; Weiss, Christian

    2014-10-01

    The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x ll 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < p(R) < several 100MeV in the nucleus rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.

  10. Cross-Polarized Magic-Angle Spinning (sup13)C Nuclear Magnetic Resonance Spectroscopic Characterization of Soil Organic Matter Relative to Culturable Bacterial Species Composition and Sustained Biological Control of Pythium Root Rot.

    PubMed

    Boehm, M J; Wu, T; Stone, A G; Kraakman, B; Iannotti, D A; Wilson, G E; Madden, L V; Hoitink, H

    1997-01-01

    We report the use of a model system that examines the dynamics of biological energy availability in organic matter in a sphagnum peat potting mix critical to sustenance of microorganism-mediated biological control of pythium root rot, a soilborne plant disease caused by Pythium ultimum. The concentration of readily degradable carbohydrate in the peat, mostly present as cellulose, was characterized by cross-polarized magic-angle spinning (sup13)C nuclear magnetic resonance spectroscopy. A decrease in the carbohydrate concentration in the mix was observed during the initial 10 weeks after potting as the rate of hydrolysis of fluorescein diacetate declined below a critical threshold level required for biological control of pythium root rot. Throughout this period, total microbial biomass and activity, based on rates of [(sup14)C]acetate incorporation into phospholipids, did not change but shifts in culturable bacterial species composition occurred. Species capable of inducing biocontrol were succeeded by pleomorphic gram-positive genera and putative oligotrophs not or less effective in control. We conclude that sustained efficacy of naturally occurring biocontrol agents was limited by energy availability to this microflora within the organic matter contained in the potting mix. We propose that this critical role of organic matter may be a key factor explaining the variability in efficacy typically encountered in the control of pythium root rot with biocontrol agents. PMID:16535481

  11. Cross-Polarized Magic-Angle Spinning (sup13)C Nuclear Magnetic Resonance Spectroscopic Characterization of Soil Organic Matter Relative to Culturable Bacterial Species Composition and Sustained Biological Control of Pythium Root Rot

    PubMed Central

    Boehm, M. J.; Wu, T.; Stone, A. G.; Kraakman, B.; Iannotti, D. A.; Wilson, G. E.; Madden, L. V.; Hoitink, H.

    1997-01-01

    We report the use of a model system that examines the dynamics of biological energy availability in organic matter in a sphagnum peat potting mix critical to sustenance of microorganism-mediated biological control of pythium root rot, a soilborne plant disease caused by Pythium ultimum. The concentration of readily degradable carbohydrate in the peat, mostly present as cellulose, was characterized by cross-polarized magic-angle spinning (sup13)C nuclear magnetic resonance spectroscopy. A decrease in the carbohydrate concentration in the mix was observed during the initial 10 weeks after potting as the rate of hydrolysis of fluorescein diacetate declined below a critical threshold level required for biological control of pythium root rot. Throughout this period, total microbial biomass and activity, based on rates of [(sup14)C]acetate incorporation into phospholipids, did not change but shifts in culturable bacterial species composition occurred. Species capable of inducing biocontrol were succeeded by pleomorphic gram-positive genera and putative oligotrophs not or less effective in control. We conclude that sustained efficacy of naturally occurring biocontrol agents was limited by energy availability to this microflora within the organic matter contained in the potting mix. We propose that this critical role of organic matter may be a key factor explaining the variability in efficacy typically encountered in the control of pythium root rot with biocontrol agents. PMID:16535481

  12. Technical Letter Report - Analysis of Ultrasonic Data on Piping Cracks at Ignalina Nuclear Power Plant Before and After Applying a Mechanical Stress Improvement Process, JCN-N6319, Task 2

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Crawford, Susan L.

    2008-02-26

    Pacific Northwest National Laboratory (PNNL) is assisting the United States Nuclear Regulatory Commission (NRC) in developing a position on the management of primary water stress corrosion cracking (PWSCC) in piping systems previously analyzed for leak-before-break (LBB). Part of this work involves determining whether inspections alone are sufficient or if inspections plus mitigation techniques are needed. The work described in this report addresses the reliability of ultrasonic phased-array (PA) examinations for inspection of cracks that have been subjected to the mitigation method of mechanical stress improvement process (MSIP). It is believed that stresses imparted during MSIP may make ultrasonic crack responses in piping welds more difficult to detect and accurately characterize. To explore this issue, data were acquired, both before and after applying MSIP, and analyzed from cracked areas in piping at the Ignalina Nuclear Power Plant (INPP) in Lithuania. This work was performed under NRC Project JCN-N6319, PWSCC in Leak-Before-Break Systems.

  13. Effects of biradical deuteration on the performance of DNP: Towards better performing polarizing agents

    DOE PAGES

    Perras, Frédéric A.; Reinig, Regina R.; Slowing, Igor I.; Sadow, Aaron D.; Pruski, Marek

    2015-11-20

    We study the effects of the deuteration of biradical polarizing agents on the efficiency of dynamic nuclear polarization (DNP) via the cross-effect. To this end, we synthesized a series of bTbK and TOTAPol biradicals with systematically increased deuterium substitution. The deuteration increases the radicals' relaxation time, thus contributing to a higher saturation factor and larger DNP enhancement, and reduces the pool of protons within the so-called spin diffusion barrier. Notably, we report that full or partial deuteration leads to improved DNP enhancement factors in standard samples, but also slows down the build-up of hyperpolarization. Improvements in DNP enhancements factors ofmore » up to 70% and time savings of up to 38% are obtained upon full deuteration. As a result, it is foreseen that this approach may be applied to other DNP polarizing agents thus enabling further sensitivity improvements.« less

  14. Effects of biradical deuteration on the performance of DNP: Towards better performing polarizing agents

    SciTech Connect

    Perras, Frédéric A.; Reinig, Regina R.; Slowing, Igor I.; Sadow, Aaron D.; Pruski, Marek

    2015-11-20

    We study the effects of the deuteration of biradical polarizing agents on the efficiency of dynamic nuclear polarization (DNP) via the cross-effect. To this end, we synthesized a series of bTbK and TOTAPol biradicals with systematically increased deuterium substitution. The deuteration increases the radicals' relaxation time, thus contributing to a higher saturation factor and larger DNP enhancement, and reduces the pool of protons within the so-called spin diffusion barrier. Notably, we report that full or partial deuteration leads to improved DNP enhancement factors in standard samples, but also slows down the build-up of hyperpolarization. Improvements in DNP enhancements factors of up to 70% and time savings of up to 38% are obtained upon full deuteration. As a result, it is foreseen that this approach may be applied to other DNP polarizing agents thus enabling further sensitivity improvements.

  15. Polarization Imaging of Radio Galaxies

    NASA Astrophysics Data System (ADS)

    Antonucci, Robert

    1991-07-01

    Spectropolarimetry of the narrow line radio galaxy 3C234 was used to show in 1982 that there is a hidden broad line region occulted by an opaque torus oriented perpendicular to the radio structure axis. Given the luminosity of the reflected light, it follows that 3C234 would be called a quasar if its orientation with respect to the line of sight were different. Since then similar results were found for five Seyfert 2's. If many NLRG's are occulted quasars in the sky plane, several statistical anomalies in the beam model for superluminal motion are understandable. However, further optical spectropolarimetry has been disappointing in this regard, at least partially because of severe dilution of reflected light by starlight, sometimes polarized, from the host galaxies. We can solve this problem by observing in the UV. Furthermore, recent observations of two NLRGs have revealed OFF- NUCLEAR dust clouds reflecting and strongly "bluening" nuclear light in two NLRG's. Such dust clouds, abundant in the merger debris surrounding many luminous radio galaxies, should show up spectacularly in UV polarization images, providing information on the beam pattern and time history of nuclear emission. We request FOC polarization images of a sample of radio galaxies. We will also get for free and with high efficiency total flux images, suitable for studying the nuclei and the anomalous young stellar populations seen in merging radio galaxies from the ground.

  16. Polarization Imaging of Radio Galaxies

    NASA Astrophysics Data System (ADS)

    Antonucci, Robert

    1996-07-01

    Spectropolarimetry of the narrow line radio galaxy 3C234 was used to show in 1982 that there is a hidden broad line region occulted by an opaque torus oriented perpendicular to the radio structure axis. Given the luminosity of the reflected light, it follows that 3C234 would be called a quasar if its orientation with respect to the line of sight were different. Since then similar results were found for five Seyfert 2's. If many NLRG's are occulted quasars in the sky plane, several statistical anomalies in the beam model for superluminal motion are understandable. However, further optical spectropolarimetry has been disappointing in this regard, at least partially because of severe dilution of reflected light by starlight, sometimes polarized, from the host galaxies. We can solve this problem by observing in the UV. Furthermore, recent observations of two NLRGs have revealed OFF- NUCLEAR dust clouds reflecting and strongly "bluening" nuclear light in two NLRG's. Such dust clouds, abundant in the merger debris surrounding many luminous radio galaxies, should show up spectacularly in UV polarization images, providing information on the beam pattern and time history of nuclear emission. We request FOC polarization images of a sample of radio galaxies. We will also get for free and with high efficiency total flux images, suitable for studying the nuclei and the anomalous young stellar populations seen in merging radio galaxies from the ground.

  17. Polarization-dependent transmittance of concentric ring plasmonic lens: a polarizing interference investigation

    NASA Astrophysics Data System (ADS)

    Mao, Lei; Zang, Tianyang; Ren, Yuan; Lei, Xinrui; Jiang, Kang; Li, Kuanguo; Lu, Yonghua; Wang, Pei

    2016-10-01

    Plasmonic lenses are widely applied to manipulate optical phase or polarization distribution in the near and far field, but its polarization-dependent optical anisotropy is seldomly reported. Not only the plasmonic mode (excited by transverse magnetic polarization), but also the photonic mode (excited by transverse electric polarization) has an effect on the field distribution. In this paper, polarization-dependent optical anisotropy of concentric ring plasmonic lens has been investigated with polarizing microscope and explained by polarizing interference theoretical model. Moreover, several kinds of plasmonic lenses are mutually compared and dramatic different optical anisotropy is found. Our work bears a fundamental importance in design of micro-nano-devices as well as provides the potential to advance the applications of polarizing interferometry into plasmonic structure characterization.

  18. Polarized internal target apparatus

    DOEpatents

    Holt, Roy J.

    1986-01-01

    A polarized internal target apparatus with a polarized gas target of improved polarization and density achieved by mixing target gas atoms with a small amount of alkali metal gas atoms, and passing a high intensity polarized light source into the mixture to cause the alkali metal gas atoms to become polarized which interact in spin exchange collisions with target gas atoms yielding polarized target gas atoms.

  19. Polarized internal target apparatus

    DOEpatents

    Holt, R.J.

    1984-10-10

    A polarized internal target apparatus with a polarized gas target of improved polarization and density (achieved by mixing target gas atoms with a small amount of alkali metal gas atoms, and passing a high intensity polarized light source into the mixture to cause the alkali metal gas atoms to become polarized which interact in spin exchange collisions with target gas atoms yielding polarized target gas atoms) is described.

  20. pH recycling aqueous two-phase systems applied in extraction of Maitake β-Glucan and mechanism analysis using low-field nuclear magnetic resonance.

    PubMed

    Hou, Huiyun; Cao, Xuejun

    2015-07-31

    In this paper, a recycling aqueous two-phase systems (ATPS) based on two pH-response copolymers PADB and PMDM were used in purification of β-Glucan from Grifola frondosa. The main parameters, such as polymer concentration, type and concentration of salt, extraction temperature and pH, were investigated to optimize partition conditions. The results demonstrated that β-Glucan was extracted into PADB-rich phase, while impurities were extracted into PMDM-rich phase. In this 2.5% PADB/2.5% PMDM ATPS, 7.489 partition coefficient and 96.92% extraction recovery for β-Glucan were obtained in the presence of 30mmol/L KBr, at pH 8.20, 30°C. The phase-forming copolymers could be recycled by adjusting pH, with recoveries of over 96.0%. Furthermore, the partition mechanism of Maitake β-Glucan in PADB/PMDM aqueous two-phase systems was studied. Fourier transform infrared spectra, ForteBio Octet system and low-field nuclear magnetic resonance (LF-NMR) were introduced for elucidating the partition mechanism of β-Glucan. Especially, LF-NMR was firstly used in the mechanism analysis in partition of aqueous two-phase systems. The change of transverse relaxation time (T2) in ATPS could reflect the interaction between polymers and β-Glucan.

  1. Status of the hydrogen and deuterium atomic beam polarized target for NEPTUN experiment

    NASA Astrophysics Data System (ADS)

    Balandikov, N. I.; Ershov, V. P.; Fimushkin, V. V.; Kulikov, M. V.; Pilipenko, Yu. K.; Shutov, V. B.

    1995-09-01

    NEPTUN-NEPTUN-A is a polarized experiment at Accelerating and Storage Complex (UNK, IHEP) with two internal targets. Status of the atomic beam polarized target that is being developed at the Joint Institute for Nuclear Research, Dubna is presented.

  2. Linearly polarized fiber amplifier

    SciTech Connect

    Kliner, Dahv A.; Koplow, Jeffery P.

    2004-11-30

    Optically pumped rare-earth-doped polarizing fibers exhibit significantly higher gain for one linear polarization state than for the orthogonal state. Such a fiber can be used to construct a single-polarization fiber laser, amplifier, or amplified-spontaneous-emission (ASE) source without the need for additional optical components to obtain stable, linearly polarized operation.

  3. Simultaneous measurement of resistively and optically detected nuclear magnetic resonance in the ν =2 /3 fractional quantum Hall regime

    NASA Astrophysics Data System (ADS)

    Akiba, Keiichirou; Nagase, Katsumi; Hirayama, Yoshiro

    2016-08-01

    We observe nuclear magnetic resonance (NMR) in the fractional quantum Hall regime at the Landau-level filling factor of ν =2 /3 from simultaneous measurement of longitudinal resistance and photoluminescence (PL). The dynamic nuclear-spin polarization is induced by applying a huge electronic current at the spin phase transition point of ν =2 /3 . The NMR spectra obtained from changes in resistance and PL intensity are qualitatively the same; that is, the Knight-shift (spin-polarized region) and zero-shift (spin-unpolarized region) resonances are observed in both. The observed change in PL intensity is interpreted as a consequence of the trion scattering induced by polarized nuclear spins. We conclude that both detection methods probe almost the same local phenomena.

  4. Nondiffracting transversally polarized beam.

    PubMed

    Yuan, G H; Wei, S B; Yuan, X-C

    2011-09-01

    Generation of a nondiffracting transversally polarized beam by means of transmitting an azimuthally polarized beam through a multibelt spiral phase hologram and then highly focusing by a high-NA lens is presented. A relatively long depth of focus (∼4.84λ) of the electric field with only radial and azimuthal components is achieved. The polarization of the wavefront near the focal plane is analyzed in detail by calculating the Stokes polarization parameters. It is found that the polarization is spatially varying and entirely transversally polarized, and the polarization singularity disappears at the beam center, which makes the central bright channel possible. PMID:21886250

  5. Crossed elliptical polarization undulator

    SciTech Connect

    Sasaki, Shigemi

    1997-05-01

    The first switching of polarization direction is possible by installing two identical helical undulators in series in a same straight section in a storage ring. By setting each undulator in a circular polarization mode in opposite handedness, one can obtain linearly polarized radiation with any required polarization direction depending on the modulator setting between two undulators. This scheme can be used without any major degradation of polarization degree in any low energy low emittance storage ring.

  6. Polarization-balanced beamsplitter

    DOEpatents

    Decker, D.E.

    1998-02-17

    A beamsplitter assembly is disclosed that includes several beamsplitter cubes arranged to define a plurality of polarization-balanced light paths. Each polarization-balanced light path contains one or more balanced pairs of light paths, where each balanced pair of light paths includes either two transmission light paths with orthogonal polarization effects or two reflection light paths with orthogonal polarization effects. The orthogonal pairing of said transmission and reflection light paths cancels polarization effects otherwise caused by beamsplitting. 10 figs.

  7. Polarization-balanced beamsplitter

    DOEpatents

    Decker, Derek E.

    1998-01-01

    A beamsplitter assembly that includes several beamsplitter cubes arranged to define a plurality of polarization-balanced light paths. Each polarization-balanced light path contains one or more balanced pairs of light paths, where each balanced pair of light paths includes either two transmission light paths with orthogonal polarization effects or two reflection light paths with orthogonal polarization effects. The orthogonal pairing of said transmission and reflection light paths cancels polarization effects otherwise caused by beamsplitting.

  8. Proceedings of the workshop on polarized targets in storage rings

    SciTech Connect

    Holt, R.J.

    1984-08-01

    Polarization phenomena have played an increasingly important part in the study of nuclei and nucleons in recent years. Polarization studies have been hampered by the relatively few and rather fragile polarized targets which are presently available. The concept of polarized gas targets in storage rings opens a much wider range of possibilities than is available in the external target geometry. This novel method will represent a considerable advance in nuclear physics and will continue to receive much attention in plans for future facilities. An internal, polarized-target station is being planned for the cooler ring at the Indiana University Cyclotron Facility. Internal targets are compatible with recent designs of electron accelerators proposed by the Massachusetts Institute of Technology and the Southeastern Universities Research Association. The key to nuclear-science programs based on internal targets pivots on recent developments in polarized atomic beam methods, which include the more recent laser-driven polarized targets. The workshop drew together a unique group of physicists in the fields of high-energy, nuclear and atomic physics. The meeting was organized in a manner that stimulated discussion among the 58 participants and focused on developments in polarized target technology and the underlying atomic physics. An impressive array of future possibilities for polarized targets as well as current developments in polarized target technology were discussed at the workshop. Abstracts of individual items from the workshop were prepared separately for the data base.

  9. Microfabricated Spin Polarized Atomic Magnetometers

    NASA Astrophysics Data System (ADS)

    Jimenez Martinez, Ricardo

    Spin polarized atomic magnetometers involve the preparation of atomic spins and their detection for monitoring magnetic fields. Due to the fact that magnetic fields are ubiquitous in our world, spin polarized atomic magnetometers are used in a wide range of applications from the detection of magnetic fields generated by the human heart and brain to the detection of nuclear magnetic resonance. In this thesis we developed microfabricated spin polarized atomic magnetometers. These sensors are based on optical pumping and spin-exchange collisions between alkali atoms and noble gases contained in microfabricated millimeter-scale vapor cells. In the first part of the thesis, we improved different features of current microfabricated optical magnetometers. Specifically, we improved the bandwidth of these devices, without degrading their magnetic field sensitivity, by broadening their magnetic resonance through spin-exchange collisions between alkali atoms. We also implemented all-optical excitation techniques to avoid problems, such as the magnetic perturbation of the environment, induced by the radio-frequency fields used in some of these sensors. In the second part of the thesis we demonstrated a microfluidic chip for the optical production and detection of hyperpolarized Xe gas through spin-exchange collisions with optically pumped Rb atoms. These devices are critical for the widespread use of spin polarized atomic magnetometers in applications requiring simple, compact, low-cost, and portable instrumentation.

  10. Applied chromodynamics

    SciTech Connect

    Brodsky, S.J.

    1983-11-01

    A number of novel features of QCD are reviewed, including the consequences of formation zone and color transparency phenomena in hadronic collisions, the use of automatic scale setting for perturbative predictions, null-zone phenomena as a fundamental test of gauge theory, and the relationship of intrinsic heavy colored particle Fock state components to new particle production. We conclude with a review of the applications of QCD to nuclear multiquark systems. 74 references.

  11. Multichannel polarization stabilization for coherently combined fiber laser arrays.

    PubMed

    Goodno, Gregory D; McNaught, Stuart J; Weber, Mark E; Weiss, S Benjamin

    2012-10-15

    We demonstrate a simplified approach toward active polarization control in coherently combined laser architectures. By leveraging optical phase dithers applied by a phase controller, polarization error signals are generated for an entire laser array from a single beam sample of the combined output, enabling closed-loop polarization locking of non-polarization-maintaining fibers. The concept is shown to be compatible with both hill-climbing and synchronous multidither phase control methods. Simultaneous phase locking and polarization locking was demonstrated for a five-fiber array with >99% phasing efficiency and >20 dB polarization extinction ratio.

  12. Italian Polar Metadata System

    NASA Astrophysics Data System (ADS)

    Longo, S.; Nativi, S.; Leone, C.; Migliorini, S.; Mazari Villanova, L.

    2012-04-01

    Italian Polar Metadata System C.Leone, S.Longo, S.Migliorini, L.Mazari Villanova, S. Nativi The Italian Antarctic Research Programme (PNRA) is a government initiative funding and coordinating scientific research activities in polar regions. PNRA manages two scientific Stations in Antarctica - Concordia (Dome C), jointly operated with the French Polar Institute "Paul Emile Victor", and Mario Zucchelli (Terra Nova Bay, Southern Victoria Land). In addition National Research Council of Italy (CNR) manages one scientific Station in the Arctic Circle (Ny-Alesund-Svalbard Islands), named Dirigibile Italia. PNRA started in 1985 with the first Italian Expedition in Antarctica. Since then each research group has collected data regarding biology and medicine, geodetic observatory, geophysics, geology, glaciology, physics and atmospheric chemistry, earth-sun relationships and astrophysics, oceanography and marine environment, chemistry contamination, law and geographic science, technology, multi and inter disciplinary researches, autonomously with different formats. In 2010 the Italian Ministry of Research assigned the scientific coordination of the Programme to CNR, which is in charge of the management and sharing of the scientific results carried out in the framework of the PNRA. Therefore, CNR is establishing a new distributed cyber(e)-infrastructure to collect, manage, publish and share polar research results. This is a service-based infrastructure building on Web technologies to implement resources (i.e. data, services and documents) discovery, access and visualization; in addition, semantic-enabled functionalities will be provided. The architecture applies the "System of Systems" principles to build incrementally on the existing systems by supplementing but not supplanting their mandates and governance arrangements. This allows to keep the existing capacities as autonomous as possible. This cyber(e)-infrastructure implements multi-disciplinary interoperability following

  13. The origin of optical polarization in NGC 1068

    NASA Technical Reports Server (NTRS)

    Angel, J. R. P.; Stockman, H. S.; Woolf, N. J.; Beaver, E. A.; Martin, P. G.

    1976-01-01

    The polarization of emission lines in the nucleus of NGC 1068 has been measured with a digicon, a single-channel scanner, and interference filters. It is found that the permitted lines of H and probably also He II are polarized at nearly the same position angle and by the same amount as the neighboring continuum. This argues strongly that a common dust scattering mechanism is responsible for all the polarization. The forbidden lines are weakly polarized at a position angle quite different from the continuum, indicating an origin outside the nuclear scattering region. The continuum radiation has been found to be circularly polarized with ellipticity of the order of 5 percent in the red. Such high ellipticity is very unlikely to be of nonthermal origin. We take it as evidence that the nuclear dust is in the form of clouds in an asymmetric skew geometry; the polarization then arises from multiple scattering within these clouds.

  14. Salinity effect on the spectral induced polarization porosimetry: theory and experiment

    NASA Astrophysics Data System (ADS)

    Niu, Q.; Revil, A.; Saidian, M.; Prasad, M.

    2015-12-01

    Spectral induced polarization (SIP) porosimetry is a new technique for characterizing the pore size distribution of a porous medium. The induced polarization of porous media under low frequencies is mainly attributed to the relaxation of the mineral/fluid interface, i.e., the electrical double layer (EDL, including both Stern and diffuse layers). Currently, the salinity effect is not considered while applying the SIP porosimetry although a number of experiments have shown the water salinity could affect the relaxation of EDL. In this study, we conducted SIP measurement of a Portland sandstone sample with a broad range of salinities. The relaxation time distributions of the sample at different salinities are obtained by inverting the measured SIP responses using the least-square method with optimized damping parameter. The modal relaxation time shows a non-negligible dependence on the salinity/fluid conductivity. The salinity dependence can be explained by considering the ions exchange between Stern and diffuse layers during polarization, i.e., diffuse layer polarization (DLP). It is also shown that the SIP porosimetry could underestimate the pore size if only Stern layer polarization is considered. It is therefore suggested to include DLP while interpreting the SIP porosimetry data in order to give consistent pore size information with other techniques such as nuclear magnetic resonance and mercury injection capillary porosimetry.

  15. Theoretical model of dynamic spin polarization of nuclei coupled to paramagnetic point defects in diamond and silicon carbide

    NASA Astrophysics Data System (ADS)

    Ivády, Viktor; Szász, Krisztián; Falk, Abram L.; Klimov, Paul V.; Christle, David J.; Janzén, Erik; Abrikosov, Igor A.; Awschalom, David D.; Gali, Adam

    2015-09-01

    Dynamic nuclear spin polarization (DNP) mediated by paramagnetic point defects in semiconductors is a key resource for both initializing nuclear quantum memories and producing nuclear hyperpolarization. DNP is therefore an important process in the field of quantum-information processing, sensitivity-enhanced nuclear magnetic resonance, and nuclear-spin-based spintronics. DNP based on optical pumping of point defects has been demonstrated by using the electron spin of nitrogen-vacancy (NV) center in diamond, and more recently, by using divacancy and related defect spins in hexagonal silicon carbide (SiC). Here, we describe a general model for these optical DNP processes that allows the effects of many microscopic processes to be integrated. Applying this theory, we gain a deeper insight into dynamic nuclear spin polarization and the physics of diamond and SiC defects. Our results are in good agreement with experimental observations and provide a detailed and unified understanding. In particular, our findings show that the defect electron spin coherence times and excited state lifetimes are crucial factors in the entire DNP process.

  16. Polarized Electron Source Developments

    SciTech Connect

    Charles K. Sinclair

    1990-02-23

    Presently, only two methods of producing beams of polarized electrons for injection into linear accelerators are in use. Each of these methods uses optical pumping by circularly polarized light to produce electron polarization. In one case, electron polarization is established in metastable helium atoms, while in the other case, the polarized electrons are produced in the conduction band of appropriate semiconductors. The polarized electrons are liberated from the helium metastable by chemi-ionization, and from the semiconductors by lowering the work function at the surface of the material. Developments with each of these sources since the 1988 Spin Physics Conference are reviewed, and the prospects for further improvements discussed.

  17. Spin-polarized spontaneous-force atom trap

    NASA Astrophysics Data System (ADS)

    Walker, T.; Feng, P.; Hoffmann, D.; Williamson, R. S., III

    1992-10-01

    We present observations of a spontaneous-force optical trap in which rubidium atoms are spin polarized by optical pumping. Stable trapping is achieved in two dimensions by the same force as in the Zeeman-shift optical trap, and in the third dimension by a macroscopic vortex force that is insensitive to light polarizations and magnetic fields. When the light along this third direction is circularly polarized and a parallel magnetic field is applied, the atoms become spin polarized.

  18. Cell polarity in plants: a PARspective on PINs.

    PubMed

    Geldner, Niko

    2009-02-01

    Plants have acquired the ability for organized multicellular development independent from animals. Because of this, they represent an independent example in nature for the development of coordinated, complex cell polarity from the simple polarity found in unicellular eukaryotes. Plants display a striking array of polarized cell types, with different axes of polarity being defined in one cell. The most investigated and best understood aspect of plant polarity is the apical-basal polarity of the PIN family of auxin efflux facilitators, which are of crucial importance for the organization of the entire plant body. Striking differences exist between the PAR-polarity modules known in animals and the ways PINs polarize plant cells. Nonetheless, a common regulatory logic probably applies to all polarizing eukaryotic cells, which includes self-reinforcing, positive feedback loops, intricate interactions between membrane-attached proteins, lipid signatures, and the targeting of transmembrane proteins to the correct domains of the plasma membrane. PMID:18993110

  19. General description of polarization in lidar using Stokes vectors and polar decomposition of Mueller matrices.

    PubMed

    Hayman, Matthew; Thayer, Jeffrey P

    2012-04-01

    Polarization measurements have become nearly indispensible in lidar cloud and aerosol studies. Despite polarization's widespread use in lidar, its theoretical description has been widely varying in accuracy and completeness. Incomplete polarization lidar descriptions invariably result in poor accountability for scatterer properties and instrument effects, reducing data accuracy and disallowing the intercomparison of polarization lidar data between different systems. We introduce here the Stokes vector lidar equation, which is a full description of polarization in lidar from laser output to detector. We then interpret this theoretical description in the context of forward polar decomposition of Mueller matrices where distinct polarization attributes of diattenuation, retardance, and depolarization are elucidated. This decomposition can be applied to scattering matrices, where volumes consisting of randomly oriented particles are strictly depolarizing, while oriented ice crystals can be diattenuating, retarding, and depolarizing. For instrument effects we provide a description of how different polarization attributes will impact lidar measurements. This includes coupling effects due to retarding and depolarization attributes of the receiver, which have no description in scalar representations of polarization lidar. We also describe how the effects of polarizance in the receiver can result in nonorthogonal polarization detection channels. This violates one of the most common assumptions in polarization lidar operation.

  20. NUCLEAR DATABASES FOR REACTOR APPLICATIONS.

    SciTech Connect

    PRITYCHENKO, B.; ARCILLA, R.; BURROWS, T.; HERMAN, M.W.; MUGHABGHAB, S.; OBLOZINSKY, P.; ROCHMAN, D.; SONZOGNI, A.A.; TULI, J.; WINCHELL, D.F.

    2006-06-05

    The National Nuclear Data Center (NNDC): An overview of nuclear databases, related products, nuclear data Web services and publications. The NNDC collects, evaluates, and disseminates nuclear physics data for basic research and applied nuclear technologies. The NNDC maintains and contributes to the nuclear reaction (ENDF, CSISRS) and nuclear structure databases along with several others databases (CapGam, MIRD, IRDF-2002) and provides coordination for the Cross Section Evaluation Working Group (CSEWG) and the US Nuclear Data Program (USNDP). The Center produces several publications and codes such as Atlas of Neutron Resonances, Nuclear Wallet Cards booklets and develops codes, such as nuclear reaction model code Empire.

  1. Ion polarization in the MEIC figure-8 ion collider ring

    SciTech Connect

    V.S. Morozov, Ya.S. Derbenev, Y. Zhang, P. Chevtsov, A.M. Kondratenko, M.A. Kondratenko, Yu.N. Filatov

    2012-07-01

    The nuclear physics program envisaged at the Medium-energy Electron-Ion Collider (MEIC) currently being developed at the Jefferson Lab calls for collisions of 3-11 GeV/c longitudinally polarized electrons and 20-100 GeV/c, in equivalent proton momentum, longitudinally/ transversely polarized protons/ deuterons/ light ions. We present a scheme that provides the required ion polarization arrangement in the MEIC's ion collider ring.

  2. Dynamic polarization of ZF in a fluorinated alcohol

    SciTech Connect

    Hill, D.; Kasprzyk, T.; Jarmer, J.J.; Penttilae, S.; Krumpolc, M.; Hoffmann, G.W.; Purcell, M.

    1988-01-01

    We have studied microwave dynamic cooling of ZF and H nuclei in mixtures of 1,1,1,3,3,3-hexafluoro-2-propanol and water, doped with Cr(V) complex. Equal spin temperatures of the two nuclei are produced, and the highest spin polarizations (/approximately/80%) are found in mixtures near the eutectic ratio. The high fluorine content and polarization make this a suitable material for polarized nuclear scattering experiments. 11 refs., 3 figs., 1 tab.

  3. Early Universe with CMB polarization

    NASA Astrophysics Data System (ADS)

    Souradeep, Tarun

    2011-12-01

    The Universe is the grandest conceivable scale on which the human mind can strive to understand nature. The amazing aspect of cosmology, the branch of science that attempts to understand the origin and evolution of the Universe, is that it is largely comprehensible by applying the same basic laws of physics that we use for other branches of physics. The observed cosmic microwave background (CMB) is understood by applying the basic laws of radiative processes and transfer, masterfully covered in the classic text by S. Chandrasekhar, in the cosmological context. In addition to the now widely acclaimed temperature anisotropy, there is also linear polarization information imprinted on the observed Cosmic Microwave background. CMB polarization already has addressed, and promises to do a lot more to unravel the deepest fundamental queries about physics operating close to the origin of the Universe.

  4. T-Violation experiment using polarized Li-8 at TRIUMF

    NASA Astrophysics Data System (ADS)

    Murata, Jiro; MTV Collaboration

    2014-09-01

    The MTV experiment searching T-Violating electron transverse polarization in polarized nuclear beta decay at TRIUMF is running. The main electron tracking detector as a Mott polarimeter was upgraded from a planer drift chamber to a cylindrical drift chamber (CDC), which has been commissioned and tested. In this talk, preparation status of the next physics production using the CDC will be presented.

  5. A Translational Polarization Rotator

    NASA Technical Reports Server (NTRS)

    Chuss, David T.; Wollack, Edward J.; Pisano, Giampaolo; Ackiss, Sheridan; U-Yen, Kongpop; Ng, Ming wah

    2012-01-01

    We explore a free-space polarization modulator in which a variable phase introduction between right- and left-handed circular polarization components is used to rotate the linear polarization of the outgoing beam relative to that of the incoming beam. In this device, the polarization states are separated by a circular polarizer that consists of a quarter-wave plate in combination with a wire grid. A movable mirror is positioned behind and parallel to the circular polarizer. As the polarizer-mirror distance is separated, an incident liear polarization will be rotated through an angle that is proportional to the introduced phase delay. We demonstrate a prototype device that modulates Stokes Q and U over a 20% bandwidth.

  6. Polarized Light Corridor Demonstrations.

    ERIC Educational Resources Information Center

    Davies, G. R.

    1990-01-01

    Eleven demonstrations of light polarization are presented. Each includes a brief description of the apparatus and the effect demonstrated. Illustrated are strain patterns, reflection, scattering, the Faraday Effect, interference, double refraction, the polarizing microscope, and optical activity. (CW)

  7. Applied Enzymology.

    ERIC Educational Resources Information Center

    Manoharan, Asha; Dreisbach, Joseph H.

    1988-01-01

    Describes some examples of chemical and industrial applications of enzymes. Includes a background, a discussion of structure and reactivity, enzymes as therapeutic agents, enzyme replacement, enzymes used in diagnosis, industrial applications of enzymes, and immobilizing enzymes. Concludes that applied enzymology is an important factor in…

  8. Graphing Polar Curves

    ERIC Educational Resources Information Center

    Lawes, Jonathan F.

    2013-01-01

    Graphing polar curves typically involves a combination of three traditional techniques, all of which can be time-consuming and tedious. However, an alternative method--graphing the polar function on a rectangular plane--simplifies graphing, increases student understanding of the polar coordinate system, and reinforces graphing techniques learned…

  9. Polarity at Many Levels

    ERIC Educational Resources Information Center

    Flannery, Maura C.

    2004-01-01

    An attempt is made to find how polarity arises and is maintained, which is a central issue in development. It is a fundamental attribute of living things and cellular polarity is also important in the development of multicellular organisms and controversial new work indicates that polarization in mammals may occur much earlier than previously…

  10. Polarization feedback laser stabilization

    DOEpatents

    Esherick, Peter; Owyoung, Adelbert

    1988-01-01

    A system for locking two Nd:YAG laser oscillators includes an optical path for feeding the output of one laser into the other with different polarizations. Elliptical polarization is incorporated into the optical path so that the change in polarization that occurs when the frequencies coincide may be detected to provide a feedback signal to control one laser relative to the other.

  11. Bumblebees Learn Polarization Patterns

    PubMed Central

    Foster, James J.; Sharkey, Camilla R.; Gaworska, Alicia V.A.; Roberts, Nicholas W.; Whitney, Heather M.; Partridge, Julian C.

    2014-01-01

    Summary Foraging insect pollinators such as bees must find and identify flowers in a complex visual environment. Bees use skylight polarization patterns for navigation [1–3], a capacity mediated by the polarization-sensitive dorsal rim area (DRA) of their eye [4, 5]. While other insects use polarization sensitivity to identify appropriate habitats [6], oviposition sites, and food sources [7], to date no nonnavigational functions of polarization vision have been identified in bees. Here we investigated the ability of bumblebees (Bombus terrestris) to learn polarization patterns on artificial “flowers” in order to obtain a food reward. We show that foraging bumblebees can learn to discriminate between two differently polarized targets, but only when the target artificial “flower” is viewed from below. A context for these results is provided by polarization imaging of bee-pollinated flowers, revealing the potential for polarization patterns in real flowers. Bees may therefore have the ability to use polarization vision, possibly mediated by their polarization-sensitive DRA, both for navigation and to learn polarization patterns on flowers, the latter being the first nonnavigational function for bee polarization vision to be identified. PMID:24909321

  12. Calculation of polarization effects

    SciTech Connect

    Chao, A.W.

    1983-09-01

    Basically there are two areas of accelerator applications that involve beam polarization. One is the acceleration of a polarized beam (most likely a proton beam) in a synchrotron. Another concerns polarized beams in an electron storage ring. In both areas, numerical techniques have been very useful.

  13. Polar Ozone Workshop. Abstracts

    NASA Technical Reports Server (NTRS)

    Aikin, Arthur C.

    1988-01-01

    Results of the proceedings of the Polar Ozone Workshop held in Snowmass, CO, on May 9 to 13, 1988 are given. Topics covered include ozone depletion, ozonometry, polar meteorology, polar stratospheric clouds, remote sensing of trace gases, atmospheric chemistry and dynamical simulations.

  14. Ferroelectric polarization in antiferromagnetically coupled ferromagnetic film

    NASA Astrophysics Data System (ADS)

    Gareeva, Z. V.; Mazhitova, F. A.; Doroshenko, R. A.

    2016-09-01

    We report the influence of interface antiferromagnetic coupling on magnetoelectric properties of ferromagnetic bi-layers. Electric polarization arising at magnetic ingomogeneity in bi-layered ferromagnetic structure with antiferromagnetic coupling at interface in applied magnetic field has been explored. Diagrams representing dependences of electric polarization on magnetic field P(H) have been constructed for two magnetic field geometries (in-plane and out-of plane fields). It has been found out that P(H) dependences demonstrate non-monotonic behavior. Peculiarities of polarization in an in-plane-oriented magnetic field have been explained by magnetization processes. It has been shown that a variety of magnetic configurations of Bloch, Neel and mixed Bloch-Neel types can be realized in antiferromagnetically coupled film due to cubic anisotropy contribution. In the area of Bloch magnetic configuration electric polarization vanishes. The critical values of magnetic fields suppressing polarization have been estimated.

  15. Nuclear spin physics in quantum dots: An optical investigation

    NASA Astrophysics Data System (ADS)

    Urbaszek, Bernhard; Marie, Xavier; Amand, Thierry; Krebs, Olivier; Voisin, Paul; Maletinsky, Patrick; Högele, Alexander; Imamoglu, Atac

    2013-01-01

    The mesoscopic spin system formed by the 104-106 nuclear spins in a semiconductor quantum dot offers a unique setting for the study of many-body spin physics in the condensed matter. The dynamics of this system and its coupling to electron spins is fundamentally different from its bulk counterpart or the case of individual atoms due to increased fluctuations that result from reduced dimensions. In recent years, the interest in studying quantum-dot nuclear spin systems and their coupling to confined electron spins has been further fueled by its importance for possible quantum information processing applications. The fascinating nonlinear (quantum) dynamics of the coupled electron-nuclear spin system is universal in quantum dot optics and transport. In this article, experimental work performed over the last decade in studying this mesoscopic, coupled electron-nuclear spin system is reviewed. Here a special focus is on how optical addressing of electron spins can be exploited to manipulate and read out the quantum-dot nuclei. Particularly exciting recent developments in applying optical techniques to efficiently establish nonzero mean nuclear spin polarizations and using them to reduce intrinsic nuclear spin fluctuations are discussed. Both results critically influence the preservation of electron-spin coherence in quantum dots. This overall recently gained understanding of the quantum-dot nuclear spin system could enable exciting new research avenues such as experimental observations of spontaneous spin ordering or nonclassical behavior of the nuclear spin bath.

  16. Valley polarization assisted spin polarization in two dimensions.

    PubMed

    Renard, V T; Piot, B A; Waintal, X; Fleury, G; Cooper, D; Niida, Y; Tregurtha, D; Fujiwara, A; Hirayama, Y; Takashina, K

    2015-01-01

    Valleytronics is rapidly emerging as an exciting area of basic and applied research. In two-dimensional systems, valley polarization can dramatically modify physical properties through electron-electron interactions as demonstrated by such phenomena as the fractional quantum Hall effect and the metal-insulator transition. Here, we address the electrons' spin alignment in a magnetic field in silicon-on-insulator quantum wells under valley polarization. In stark contrast to expectations from a non-interacting model, we show experimentally that less magnetic field can be required to fully spin polarize a valley-polarized system than a valley-degenerate one. Furthermore, we show that these observations are quantitatively described by parameter-free ab initio quantum Monte Carlo simulations. We interpret the results as a manifestation of the greater stability of the spin- and valley-degenerate system against ferromagnetic instability and Wigner crystalization, which in turn suggests the existence of a new strongly correlated electron liquid at low electron densities. PMID:26027889

  17. Valley polarization assisted spin polarization in two dimensions

    PubMed Central

    Renard, V. T.; Piot, B. A.; Waintal, X.; Fleury, G.; Cooper, D.; Niida, Y.; Tregurtha, D.; Fujiwara, A.; Hirayama, Y.; Takashina, K.

    2015-01-01

    Valleytronics is rapidly emerging as an exciting area of basic and applied research. In two-dimensional systems, valley polarization can dramatically modify physical properties through electron–electron interactions as demonstrated by such phenomena as the fractional quantum Hall effect and the metal-insulator transition. Here, we address the electrons' spin alignment in a magnetic field in silicon-on-insulator quantum wells under valley polarization. In stark contrast to expectations from a non-interacting model, we show experimentally that less magnetic field can be required to fully spin polarize a valley-polarized system than a valley-degenerate one. Furthermore, we show that these observations are quantitatively described by parameter-free ab initio quantum Monte Carlo simulations. We interpret the results as a manifestation of the greater stability of the spin- and valley-degenerate system against ferromagnetic instability and Wigner crystalization, which in turn suggests the existence of a new strongly correlated electron liquid at low electron densities. PMID:26027889

  18. Valley polarization assisted spin polarization in two dimensions.

    PubMed

    Renard, V T; Piot, B A; Waintal, X; Fleury, G; Cooper, D; Niida, Y; Tregurtha, D; Fujiwara, A; Hirayama, Y; Takashina, K

    2015-06-01

    Valleytronics is rapidly emerging as an exciting area of basic and applied research. In two-dimensional systems, valley polarization can dramatically modify physical properties through electron-electron interactions as demonstrated by such phenomena as the fractional quantum Hall effect and the metal-insulator transition. Here, we address the electrons' spin alignment in a magnetic field in silicon-on-insulator quantum wells under valley polarization. In stark contrast to expectations from a non-interacting model, we show experimentally that less magnetic field can be required to fully spin polarize a valley-polarized system than a valley-degenerate one. Furthermore, we show that these observations are quantitatively described by parameter-free ab initio quantum Monte Carlo simulations. We interpret the results as a manifestation of the greater stability of the spin- and valley-degenerate system against ferromagnetic instability and Wigner crystalization, which in turn suggests the existence of a new strongly correlated electron liquid at low electron densities.

  19. Target information enhancement using polarized component of infrared images

    NASA Astrophysics Data System (ADS)

    Qiu, Tiaowen; Zhang, Yan; Li, Jicheng; Yang, Weiping

    2014-11-01

    After a deep study of the principle of infrared polarization imaging detection, the infrared polarization information of target and background is modeled. Considering the partial polarized light can be obtained by the superposition of natural light (unpolarized light) and linearly polarized component while ignoring the component of circularly polarized light, and combing with the degree of polarization (DOLP) and the angle of polarization (AOP), the infrared polarization information is expressed by the multiplying of an intensity factor by a polarization factor. What we have modeled not only can be used to analyze the infrared polarization information visually and profoundly, but also make the extraction of polarized features convenient. Then, faced with different application fields and based on the model, a target information enhancement program is proposed, which is achieved by extracting a linear polarization component in a certain polarized direction. This program greatly improves the contrast between target and background, and can be applied in target detection or identification, especially for camouflage or stealth target. At last, we preliminarily tested the proposed enhancement method exploiting infrared polarization images obtained indoor and outdoor, which demonstrates the effectiveness of the enhancement program.

  20. Applied geophysics

    SciTech Connect

    Dohr, G.

    1981-01-01

    This book discusses techniques which play a predominant role in petroleum and natural gas exploration. Particular emphasis has been placed on modern seismics which today claims over 90% of man-power and financial resources in exploration. The processing of geophysical data is the most important factor in applied physics and emphasis is placed on it in the discussion of exploration problems. Chapter titles include: refraction seismics; reflection seismics; seismic field techniques; digital seismics-electronic data processing; digital seismics-practical application; recent developments, special seismic procedures; gravitational methods; magnetic methods; geoelectric methods; well-logging; and miscellaneous methods in applied geophysics (thermal methods, radioactive dating, natural radioactivity surveys, and surface detection of gas. (DMC)

  1. Hybrid polarity SAR architecture

    NASA Astrophysics Data System (ADS)

    Raney, R. Keith

    2009-05-01

    A space-based synthetic aperture radar (SAR) designed to provide quantitative information on a global scale implies severe requirements to maximize coverage and to sustain reliable operational calibration. These requirements are best served by the hybrid-polarity architecture, in which the radar transmits in circular polarization, and receives on two orthogonal linear polarizations, coherently, retaining their relative phase. This paper summarizes key attributes of hybrid-polarity dual- and quadrature-polarized SARs, reviews the associated advantages, formalizes conditions under which the signal-to-noise ratio is conserved, and describes the evolution of this architecture from first principles.

  2. Applied Nanotoxicology.

    PubMed

    Hobson, David W; Roberts, Stephen M; Shvedova, Anna A; Warheit, David B; Hinkley, Georgia K; Guy, Robin C

    2016-01-01

    Nanomaterials, including nanoparticles and nanoobjects, are being incorporated into everyday products at an increasing rate. These products include consumer products of interest to toxicologists such as pharmaceuticals, cosmetics, food, food packaging, household products, and so on. The manufacturing of products containing or utilizing nanomaterials in their composition may also present potential toxicologic concerns in the workplace. The molecular complexity and composition of these nanomaterials are ever increasing, and the means and methods being applied to characterize and perform useful toxicologic assessments are rapidly advancing. This article includes presentations by experienced toxicologists in the nanotoxicology community who are focused on the applied aspect of the discipline toward supporting state of the art toxicologic assessments for food products and packaging, pharmaceuticals and medical devices, inhaled nanoparticle and gastrointestinal exposures, and addressing occupational safety and health issues and concerns. This symposium overview article summarizes 5 talks that were presented at the 35th Annual meeting of the American College of Toxicology on the subject of "Applied Nanotechnology." PMID:26957538

  3. Polarization distance: a framework for modelling object detection by polarization vision systems.

    PubMed

    How, Martin J; Marshall, N Justin

    2014-02-01

    The discrimination of polarized light is widespread in the natural world. Its use for specific, large-field tasks, such as navigation and the detection of water bodies, has been well documented. Some species of cephalopod and crustacean have polarization receptors distributed across the whole visual field and are thought to use polarized light cues for object detection. Both object-based polarization vision systems and large field detectors rely, at least initially, on an orthogonal, two-channel receptor organization. This may increase to three-directional analysis at subsequent interneuronal levels. In object-based and some of the large-field tasks, the dominant e-vector detection axes are often aligned (through eye, head and body stabilization mechanisms) horizontally and vertically relative to the outside world. We develop Bernard and Wehner's 1977 model of polarization receptor dynamics to apply it to the detection and discrimination of polarized objects against differently polarized backgrounds. We propose a measure of 'polarization distance' (roughly analogous to 'colour distance') for estimating the discriminability of objects in polarized light, and conclude that horizontal/vertical arrays are optimally designed for detecting differences in the degree, and not the e-vector axis, of polarized light under natural conditions.

  4. On the polarization of non-Gaussian optical quantum field: Higher-order optical-polarization

    SciTech Connect

    Singh, Ravi S.; Prakash, Hari

    2013-06-15

    Polarization of light signifies transversal, anisotropic and asymmetrical statistical properties of electromagnetic radiation about the direction of propagation. Traditionally, optical-polarization is characterized by Stokes’ theory susceptible to be insufficient in assessing the polarization structure of optical quantum fields and, also, does not decipher the twin characteristic polarization parameters (‘ratio of real amplitudes and difference in phases’). An alternative way, in the spirit of classical description of optical-polarization, is introduced which can be generalized to deal higher-order polarization of quantum light, particularly, prepared in non-Gaussian Schrodinger Cat or Cat-like states and entangled bi-modal coherent states. On account of pseudo mono-modal or multi-modal nature of such optical quantum field, higher-order polarization is seen to be highly sensitive to the basis of description. -- Highlights: •We have generalized the usual concept of optical-polarization. •A concept of higher-order optical-polarization is introduced. •This concept is applied to compute the polarization-parameters of non-Gaussian Optical field. •To the best of our knowledge, no study is performed which investigates such optical quantum field.

  5. Space nuclear power applied to electric propulsion

    NASA Technical Reports Server (NTRS)

    Vicente, F. A.; Karras, T.; Darooka, D.; Isenberg, L.

    1989-01-01

    Space reactor power systems with characteristics ideal for advanced spacecraft systems applications are discussed. These characteristics are: high power-to-weight ratio (15 to 33 W/kg); high volume density (high ballistic coefficient); no preferential orientation in orbit; long operational life; high reliability; and total launch and operational safety. These characteristics allow the use of electric propulsion to raise spacecraft from low earth parking orbits to operational orbits, greatly increasing the useful orbit payload for a given launch vehicle by eliminating the need for a separation injection stage. A proposed demonstration mission is described.

  6. Nuclear techniques applied to dementia studies

    SciTech Connect

    Ehmann, W.D.

    1996-12-31

    Trace element imbalances have been implicated in the etiology and/or pathogenesis of several dementing disorders related to aging. Of these diseases, Alzheimer`s disease (AD) is by far the most prevalent. Many elemental imbalances have been reported in AD brain, compared to neurologically normal controls. Using instrumental neutron activation analysis (INAA), we have observed significant increases (p {le} 0.05) in bromine, chlorine, mercury, sodium, and phosphorus and decreased amounts of cesium, nitrogen, and rubidium in AD brain, compared to age-matched control brain. Because INAA is a simultaneous multielement method that does not require tissue dissolution, fewer opportunities for contamination exist than with otherwise powerful analytical methods, such as inductively coupled plasma mass spectrometry or atomic absorption spectrometry. Although INAA is a very important tool in the study of potential trace element involvement in dementia, we have often found it necessary to go beyond conventional INAA methods.

  7. Welding technologies as applied to nuclear manufacturing

    NASA Astrophysics Data System (ADS)

    Roper, J. R.

    1992-10-01

    This is the trip report of John R. Roper, who traveled to England 25 Sep. through 8 Oct. 1992. Dr. Roper attended the US/UK JOWOG 22-D Joining Technical Exchange meeting and gave a presentation on Welding Finite Element Analysis and the Precision Joining Center at the Atomic Weapons Establishment in Aldermaston, United Kingdom. Dr. Roper also toured the Welding Institute in Abington, UK and discussed technology exchange of weld thermal and mechanical material responses.

  8. Materials technology applied to nuclear accelerator targets

    SciTech Connect

    Barthell, B.L.

    1986-11-10

    The continuing requests for both shaped and flat, very low areal density metal foils have led to the development of metallurgical quality, high strength products. Intent of this paper is to show methods of forming structures on various substrates using periodic vapor interruptions, alternating anodes, and mechanical peening to alter otherwise unacceptable grain morphology which both lowers tensile strength and causes high stresses in thin films. The three technologies, physical vapor deposition, electrochemistry, and chemical vapor deposition and their thin film products can benefit from the use of laminate technology and control of grain structure morphology through the use of materials research and technology.

  9. Terahertz polarization modulator based on metasurface

    NASA Astrophysics Data System (ADS)

    He, Jingwen; Xie, Zhenwei; Wang, Sen; Wang, Xinke; Kan, Qiang; Zhang, Yan

    2015-10-01

    Based on the metasurface composed of C-shaped slit (CSS) antennas, a broadband transmitted terahertz (THz) polarization modulator (TPM) is proposed and experimentally verified. By rotating the designed TPM, the amplitudes and phase difference of the two orthogonal electric components can be tuned, and thus the polarization of the transmitted THz beam is modulated. The linear-to-linear and linear-to-elliptical polarization conversion is realized with the proposed TPM. Numerical simulations are also performed and agree well with the experimental measurements. The proposed concept can be applied to other wavebands simply by varying the structure parameters and the material of the substrate.

  10. Polarization in remote sensing

    NASA Astrophysics Data System (ADS)

    Egan, Walter G.

    1992-12-01

    A review of the experimental and theoretical aspects of optical polarization is presented with definitions of the observed polarization characteristics and relationship to the Stokes parameters. A typical terrestrial soil polarization curve is characterized and related to the current theoretical knowledge. This polarization relationship is extended to cover planetary surfaces, such as the Moon, and Mars and terrestrial surfaces composed of farm areas and water surfaces. Instrumentation for imaging and non-imaging polarimetry are described including the use of focal plane arrays. Recent Space Shuttle polarimetric observations of the region around the Island of Hawaii and New Madrid, Missouri are described, as well as concurrent cloud and haze observations. Polarization is a sensitive indicator of cloud particle size distributions, soil texture, farm crops, sea state and atmospheric aerosols and haze. Cloud particle size distributions are uniquely characterized by polarization, and this cannot be achieved with photometry. An extensive bibliography of polarization in remote sensing is appended.

  11. Polarity inversion in polar-nonpolar-polar heterostructures.

    PubMed

    Cho, S; Youn, S J; Kim, Y; DiVenere, A; Wong, G K; Freeman, A J; Ketterson, J B

    2001-09-17

    We have observed an epilayer-thickness-dependent polarity inversion for the growth of CdTe on Sb(Bi)/CdTe(111)B. For films with Sb(Bi) thicknesses of less than 40 A (15 A), the CdTe layer shows a B (Te-terminated) face, but it switches to an A (Cd-terminated) face for thicker layers. On the other hand, a CdTe layer grown on Bi(Sb)/CdTe(111)A always shows the A face regardless of Sb or Bi layer thicknesses. In order to address the observations we have performed ab initio calculations, which suggest that the polarity of a polar material on a nonpolar one results from the binding energy difference between the two possible surface configurations.

  12. Generation of radially polarized light beams of high quality using a step-index optical fiber

    NASA Astrophysics Data System (ADS)

    Ma, Yuzhao

    2012-03-01

    We present an experimental setup to generate radially polarized beams without using high-cost optical elements. In the setup a four-segment polarization converter is used in front of the fiber to produce a pseudo radially polarized beam. A traditional step-index fiber which supports only LP01 and LP11 modes is then used as a mode-cleaning device. A commercial mechanical fiber-squeezer polarization controller is applied to produce adequate pressure and twist onto the fiber. The four-segment polarization converter and the fiber squeezer polarization controller are adjusted by turns for improving the beam quality in intensity and polarization. Additionally, several methods of characterizing the polarization properties of radially polarized beams are reviewed. One of the latest methods is applied for characterizing the polarization properties of the radially polarized beams produced by using our technique. The results show the highquality of the obtained beams.

  13. Birefringent polarization ray tracing: Theory and applications

    NASA Astrophysics Data System (ADS)

    McClain, Stephen Charles

    1992-06-01

    Birefringent polarization ray tracing is an extension of geometric ray tracing. In addition to calculating ray paths and phases, it also analyzes the state of polarization through birefringent devices. Some systems containing birefringent elements include optical computers, radiometers, optical isolators, bar code scanners, and optical data storage systems. This dissertation derives explicit algorithms for polarization ray tracing through anisotropic media, optically active media, and anisotropic optically active media, such as quartz. The objective was to go beyond the electromagnetic relations to establish algorithms in standard ray tracing format, ready for direct inclusion into lens design software. The algorithms, derived from Maxwell's equations, constitutive relations, and boundary conditions, calculate the wavevector, ray vector, optical path length, refractive index, and polarization state of a ray. Generalized Fresnel relations govern the division of energy at each interface into two transmitted and two reflected modes. The algorithms are applied to calculate the polarization aberrations of a variety of birefringent devices. In particular, it is established that the polarization properties of quartz vary significantly (greater than 20 percent) over angles of only 5 degrees. This limits the useful field of view of quartz devices. Field of view aberrations of birefringent elements can critically affect the performance of optical systems. Also, design guidelines are presented for pseudodepolarizers. These devices spatially scramble the polarization. Inserted into an instrument, a depolarizer negates the polarization sensitivity of the elements which follow it. Presented in detail is the design and analysis of a depolarizer for use in a spectrometer on NASA's Earth Observing System (EOS).

  14. Applied Koopmanisma)

    NASA Astrophysics Data System (ADS)

    Budišić, Marko; Mohr, Ryan; Mezić, Igor

    2012-12-01

    A majority of methods from dynamical system analysis, especially those in applied settings, rely on Poincaré's geometric picture that focuses on "dynamics of states." While this picture has fueled our field for a century, it has shown difficulties in handling high-dimensional, ill-described, and uncertain systems, which are more and more common in engineered systems design and analysis of "big data" measurements. This overview article presents an alternative framework for dynamical systems, based on the "dynamics of observables" picture. The central object is the Koopman operator: an infinite-dimensional, linear operator that is nonetheless capable of capturing the full nonlinear dynamics. The first goal of this paper is to make it clear how methods that appeared in different papers and contexts all relate to each other through spectral properties of the Koopman operator. The second goal is to present these methods in a concise manner in an effort to make the framework accessible to researchers who would like to apply them, but also, expand and improve them. Finally, we aim to provide a road map through the literature where each of the topics was described in detail. We describe three main concepts: Koopman mode analysis, Koopman eigenquotients, and continuous indicators of ergodicity. For each concept, we provide a summary of theoretical concepts required to define and study them, numerical methods that have been developed for their analysis, and, when possible, applications that made use of them. The Koopman framework is showing potential for crossing over from academic and theoretical use to industrial practice. Therefore, the paper highlights its strengths in applied and numerical contexts. Additionally, we point out areas where an additional research push is needed before the approach is adopted as an off-the-shelf framework for analysis and design.

  15. Integrated polarizers based on tapered highly birefringent photonic crystal fibers.

    PubMed

    Romagnoli, Priscila; Biazoli, Claudecir R; Franco, Marcos A R; Cordeiro, Cristiano M B; de Matos, Christiano J S

    2014-07-28

    This paper proposes and demonstrates the creation of sections with a high polarization dependent loss (PDL) in a commercial highly birefringent (polarization maintaining) photonic crystal fiber (PCF), via tapering with pressure applied to the holes. The tapers had a 1-cm-long uniform section with a 66% scale reduction, in which the original microstructure aspect ratio was kept by the pressure application. The resulting waveguides show polarizing action across the entire tested wavelength range, 1510-1600 nm, with a peak PDL of 35.3 dB/cm (c.f. ~1 dB/cm for a typical commercial polarizing fiber). The resulting structure, as well as its production, is extremely simple, and enable a small section with a high PDL to be obtained in a polarization maintaining PCF, meaning that the polarization axes in the polarizing and polarization maintaining sections are automatically aligned. PMID:25089397

  16. Applied antineutrino physics workshop.

    SciTech Connect

    Lund, James C.

    2008-01-01

    This workshop is the fourth one of a series that includes the Neutrino Geophysics Conference at Honolulu, Hawaii, which I attended in 2005. This workshop was organized by the Astro-Particle and Cosmology laboratory in the recently opened Condoret building of the University of Paris. More information, including copies of the presentations, on the workshop is available on the website: www.apc.univ-paris7.fr/AAP2007/. The workshop aims at opening neutrino physics to various fields such that it can be applied in geosciences, nuclear industry (reactor and spent fuel monitoring) and non-proliferation. The workshop was attended by over 60 people from Europe, USA, Asia and Brazil. The meeting was also attended by representatives of the Comprehensive nuclear-Test Ban Treaty (CTBT) and the International Atomic Energy Agency (IAEA). The workshop also included a workshop dinner on board of a river boat sailing the Seine river.

  17. All-optical polarization control and noise cleaning based on a nonlinear lossless polarizer

    NASA Astrophysics Data System (ADS)

    Barozzi, Matteo; Vannucci, Armando; Picchi, Giorgio

    2015-01-01

    We propose an all-optical fiber-based device able to accomplish both polarization control and OSNR enhancement of an amplitude modulated optical signal, affected by unpolarized additive white Gaussian noise, at the same time. The proposed noise cleaning device is made of a nonlinear lossless polarizer (NLP), that performs polarization control, followed by an ideal polarizing filter that removes the orthogonally polarized half of additive noise. The NLP transforms every input signal polarization into a unique, well defined output polarization (without any loss of signal energy) and its task is to impose a signal polarization aligned with the transparent eigenstate of the polarizing filter. In order to effectively control the polarization of the modulated signal, we show that two different NLP configurations (with counter- or co-propagating pump laser) are needed, as a function of the signal polarization coherence time. The NLP is designed so that polarization attraction is effective only on the "noiseless" (i.e., information-bearing) component of the signal and not on noise, that remains unpolarized at the NLP output. Hence, the proposed device is able to discriminate signal power (that is preserved) from in-band noise power (that is partly suppressed). Since signal repolarization is detrimental if applied to polarization-multiplexed formats, the noise cleaner application is limited here to "legacy" links, with 10 Gb/s OOK modulation, still representing the most common format in deployed networks. By employing the appropriate NLP configurations, we obtain an OSNR gain close to 3dB. Furthermore, we show how the achievable OSNR gain can be estimated theoretically.

  18. Magnetic resonance imaging of convection in laser-polarized xenon

    NASA Technical Reports Server (NTRS)

    Mair, R. W.; Tseng, C. H.; Wong, G. P.; Cory, D. G.; Walsworth, R. L.

    2000-01-01

    We demonstrate nuclear magnetic resonance (NMR) imaging of the flow and diffusion of laser-polarized xenon (129Xe) gas undergoing convection above evaporating laser-polarized liquid xenon. The large xenon NMR signal provided by the laser-polarization technique allows more rapid imaging than one can achieve with thermally polarized gas-liquid systems, permitting shorter time-scale events such as rapid gas flow and gas-liquid dynamics to be observed. Two-dimensional velocity-encoded imaging shows convective gas flow above the evaporating liquid xenon, and also permits the measurement of enhanced gas diffusion near regions of large velocity variation.

  19. Locking electron spins into resonance by electron-nuclear feedback

    NASA Astrophysics Data System (ADS)

    Nowack, Katja

    2009-03-01

    All basic building blocks for spin-based quantum information processing using electron spins in GaAs quantum dots have recently been realized. Recent experiments have shown single-shot read-out of an individual spin [1], the implementation of the SWAP gate [2] and (magnetically induced) coherent single electron spin rotations [3]. However, the main drawback of using electron spins in a GaAs environment is the short spin coherence time, which is measured to be in the nanosecond range [2,4]. The source of this fast decoherence is the hyperfine interaction of the localized electron spin with the randomly fluctuating nuclear spins of the host lattice. The fluctuations of the nuclear spins have to be reduced to extend the electron spin coherence time. We therefore study the electron-nuclear spin interaction and use magnetically driven spin resonance to control the electron spin and indirectly manipulate the nuclear spins. We apply continuous microwave excitation to the electron spin and observe strong electron-nuclear feedback. One experimental signature of this feedback is the locking of the electron spin system into resonance with the microwaves. Once the electron spin is locked into resonance, this resonance condition remains fullfilled even when the external magnetic field or the microwave frequency is changed. This is due to dynamically build up nuclear polarizations (up to 500 mT) which generally counteract the external magnetic field. Locking of the electron spin system into resonance might indicate that the nuclear polarization exhibits stable configurations where fluctuations of the nuclear distribution are reduced [5]. [4pt] References [0pt] [1] J. M. Elzerman et al. , Nature 430, 431 (2004) [0pt] [2]. J. R. Petta et al., Science 309, 2180 (2005). [0pt] [3] F. H. L. Koppens et al., Nature 442, 766 (2006). [0pt] [4] F. H. L. Koppens et al., Phys. Rev. Lett. 100, 236802 (2008). [0pt] [5] J. Danon and Yu. V. Nazarov, private communication.

  20. Synthesis of quantum chromodynamics and nuclear physics

    SciTech Connect

    Brodsky, S.J.; Lepage, G.P.

    1980-08-01

    The asymptotic freedom behavior of quantum chromodynamics allows the rigorous calculation of hadronic and nuclear amplitudes at short distances by perturbative methods. The implications of QCD for large-momentum-transfer nuclear form factors and scattering processes, as well as for the structure of nuclear wave functions and nuclear interactions at short distances, are discussed. The necessity for color-polarized internal nuclear states is also discussed. 6 figures.

  1. Polarization phenomena in quantum chromodynamics

    SciTech Connect

    Brodsky, S.J.

    1994-03-01

    The author discusses a number of interrelated hadronic spin effects which test fundamental features of perturbative and non-perturbative QCD. For example, the anomalous magnetic moment of the proton and the axial coupling g{sub A} on the nucleon are shown to be related to each other for fixed proton radius, independent of the form of the underlying three-quark relativistic quark wavefunction. The renormalization scale and scheme ambiguities for the radiative corrections to the Bjorken sum rule for the polarized structure functions can be eliminated by using commensurate scale relations with other observables. Other examples include (a) new constraints on the shape and normalization of the polarized quark and gluon structure functions of the proton at large and small x{sub bj}; (b) consequences of the principle of hadron helicity retention in high x{sub F} inclusive reactions; (c) applications of hadron helicity conservation to high momentum transfer exclusive reactions; and (d) the dependence of nuclear structure functions and shadowing on virtual photon polarization. He also discusses the implications of a number of measurements which are in striking conflict with leading-twist perturbative QCD predictions, such as the extraordinarily large spin correlation A{sub NN} observed in large angle proton-proton scattering, the anomalously large {rho}{pi} branching ratio of the J/{psi}, and the rapidly changing polarization dependence of both J/{psi} and continuum lepton pair hadroproduction observed at large x{sub F}. The azimuthal angular dependence of the Drell-Yan process is shown to be highly sensitive to the projectile distribution amplitude, the fundamental valence light-cone wavefunction of the hadron.

  2. Property evaluation on the spontaneous polarity for nanopowders.

    PubMed

    Meng, Junping; Liang, Jinsheng; Ding, Yan; Han, Yilin; Yuan, Youde

    2011-11-01

    For the tourmaline fine powders, in view of their low polarized charge density and easily occurred neutralization, a new evaluation model on the spontaneous polarity was proposed. By adjusting the temperature and applying electric field, the polarized charge could be measured. On this basis, a portable evaluation device was designed and assembled into four parts: Voltage Input Unit, Temperature Control Unit, Sample Loading Unit, and Charge Detection Unit. Using the designed device, the property evaluation on the spontaneous polarity of tourmaline fine powders was carried out. The spontaneous polarization intensity was finally achieved. After experimental verification, the method had the characteristics of easy operation and high accuracy. PMID:22413324

  3. Property evaluation on the spontaneous polarity for nanopowders.

    PubMed

    Meng, Junping; Liang, Jinsheng; Ding, Yan; Han, Yilin; Yuan, Youde

    2011-11-01

    For the tourmaline fine powders, in view of their low polarized charge density and easily occurred neutralization, a new evaluation model on the spontaneous polarity was proposed. By adjusting the temperature and applying electric field, the polarized charge could be measured. On this basis, a portable evaluation device was designed and assembled into four parts: Voltage Input Unit, Temperature Control Unit, Sample Loading Unit, and Charge Detection Unit. Using the designed device, the property evaluation on the spontaneous polarity of tourmaline fine powders was carried out. The spontaneous polarization intensity was finally achieved. After experimental verification, the method had the characteristics of easy operation and high accuracy.

  4. Applied geodesy

    SciTech Connect

    Turner, S.

    1987-01-01

    This volume is based on the proceedings of the CERN Accelerator School's course on Applied Geodesy for Particle Accelerators held in April 1986. The purpose was to record and disseminate the knowledge gained in recent years on the geodesy of accelerators and other large systems. The latest methods for positioning equipment to sub-millimetric accuracy in deep underground tunnels several tens of kilometers long are described, as well as such sophisticated techniques as the Navstar Global Positioning System and the Terrameter. Automation of better known instruments such as the gyroscope and Distinvar is also treated along with the highly evolved treatment of components in a modern accelerator. Use of the methods described can be of great benefit in many areas of research and industrial geodesy such as surveying, nautical and aeronautical engineering, astronomical radio-interferometry, metrology of large components, deformation studies, etc.

  5. ATOMIC BEAM POLARIZATION MEASUREMENT OF THE RHIC POLARIZED H-JET TARGET.

    SciTech Connect

    MAKDISI,Y.; NASS,A.; GRAHAM,D.; KPONOU,A.; MAHLER,G.; MENG,W.; RITTER,J.; ET AL.

    2005-01-28

    The RHIC polarized H-Jet measures the polarization of the RHIC proton beam via elastic scattering off a nuclear polarized atomic hydrogen beam. The atomic beam is produced by a dissociator, a beam forming system and sextupole magnets. Nuclear polarization is achieved by exchanging occupation numbers of hyperfine states using high frequency transitions. The polarization was measured using a modified form of a Breit-Rabi polarimeter including focusing magnets and another set of high frequency transitions. The sampling of a large part of the beam and low noise electronics made it possible to measure the polarization to a high degree of accuracy in a very short time period (1 min). Using this system, we measured no depolarization of the atomic beam due to the RF fields of the bunched proton beam. Time-of-Flight measurements were done using a fast chopper and a QMA at the position of the RHIC interaction point to determine the areal density of the atomic beam seen by the RHIC beam.

  6. [Review] Polarization and Polarimetry

    NASA Astrophysics Data System (ADS)

    Trippe, Sascha

    2014-02-01

    Polarization is a basic property of light and is fundamentally linked to the internal geometry of a source of radiation. Polarimetry complements photometric, spectroscopic, and imaging analyses of sources of radiation and has made possible multiple astrophysical discoveries. In this article I review (i) the physical basics of polarization: electromagnetic waves, photons, and parameterizations; (ii) astrophysical sources of polarization: scattering, synchrotron radiation, active media, and the Zeeman, Goldreich-Kylafis, and Hanle effects, as well as interactions between polarization and matter (like birefringence, Faraday rotation, or the Chandrasekhar-Fermi effect); (iii) observational methodology: on-sky geometry, influence of atmosphere and instrumental polarization, polarization statistics, and observational techniques for radio, optical, and X/γ wavelengths; and (iv) science cases for astronomical polarimetry: solar and stellar physics, planetary system bodies, interstellar matter, astrobiology, astronomical masers, pulsars, galactic magnetic fields, gamma-ray bursts, active galactic nuclei, and cosmic microwave background radiation.

  7. Automatic Bayesian polarity determination

    NASA Astrophysics Data System (ADS)

    Pugh, D. J.; White, R. S.; Christie, P. A. F.

    2016-07-01

    The polarity of the first motion of a seismic signal from an earthquake is an important constraint in earthquake source inversion. Microseismic events often have low signal-to-noise ratios, which may lead to difficulties estimating the correct first-motion polarities of the arrivals. This paper describes a probabilistic approach to polarity picking that can be both automated and combined with manual picking. This approach includes a quantitative estimate of the uncertainty of the polarity, improving calculation of the polarity probability density function for source inversion. It is sufficiently fast to be incorporated into an automatic processing workflow. When used in source inversion, the results are consistent with those from manual observations. In some cases, they produce a clearer constraint on the range of high-probability source mechanisms, and are better constrained than source mechanisms determined using a uniform probability of an incorrect polarity pick.

  8. Polarization feedback laser stabilization

    DOEpatents

    Esherick, P.; Owyoung, A.

    1987-09-28

    A system for locking two Nd:YAG laser oscillators includes an optical path for feeding the output of one laser into the other with different polarizations. Elliptical polarization is incorporated into the optical path so that the change in polarization that occurs when the frequencies coincide may be detected to provide a feedback signal to control one laser relative to the other. 4 figs.

  9. NASA Applied Sciences Program

    NASA Technical Reports Server (NTRS)

    Estes, Sue M.; Haynes, J. A.

    2009-01-01

    NASA's strategic Goals: a) Develop a balanced overall program of science, exploration, and aeronautics consistent with the redirection of human spaceflight program to focus on exploration. b) Study Earth from space to advance scientific understanding and meet societal needs. NASA's partnership efforts in global modeling and data assimilation over the next decade will shorten the distance from observations to answers for important, leading-edge science questions. NASA's Applied Sciences program will continue the Agency's efforts in benchmarking the assimilation of NASA research results into policy and management decision-support tools that are vital for the Nation's environment, economy, safety, and security. NASA also is working with NOAH and inter-agency forums to transition mature research capabilities to operational systems, primarily the polar and geostationary operational environmental satellites, and to utilize fully those assets for research purposes.

  10. Polarization at SLC

    SciTech Connect

    Swartz, M.L.

    1988-07-01

    The SLAC Linear Collider has been designed to readily accommodate polarized electron beams. Considerable effort has been made to implement a polarized source, a spin rotation system, and a system to monitor the beam polarization. Nearly all major components have been fabricated. At the current time, several source and polarimeter components have been installed. The installation and commissioning of the entire system will take place during available machine shutdown periods as the commissioning of SLC progresses. It is expected that a beam polarization of 45% will be achieved with no loss in luminosity. 13 refs., 15 figs.

  11. 3D nuclear architecture reveals coupled cell cycle dynamics of chromatin and nuclear pores in the malaria parasite Plasmodium falciparum.

    PubMed

    Weiner, Allon; Dahan-Pasternak, Noa; Shimoni, Eyal; Shinder, Vera; von Huth, Palle; Elbaum, Michael; Dzikowski, Ron

    2011-07-01

    The deadliest form of human malaria is caused by the protozoan parasite Plasmodium falciparum. The complex life cycle of this parasite is associated with tight transcriptional regulation of gene expression. Nuclear positioning and chromatin dynamics may play an important role in regulating P. falciparum virulence genes. We have applied an emerging technique of electron microscopy to construct a 3D model of the parasite nucleus at distinct stages of development within the infected red blood cell. We have followed the distribution of nuclear pores and chromatin throughout the intra-erythrocytic cycle, and have found a striking coupling between the distributions of nuclear pores and chromatin organization. Pore dynamics involve clustering, biogenesis, and division among daughter cells, while chromatin undergoes stage-dependent changes in packaging. Dramatic changes in heterochromatin distribution coincide with a previously identified transition in gene expression and nucleosome positioning during the mid-to-late schizont phase. We also found a correlation between euchromatin positioning at the nuclear envelope and the local distribution of nuclear pores, as well as a dynamic nuclear polarity during schizogony. These results suggest that cyclic patterns in gene expression during parasite development correlate with gross changes in cellular and nuclear architecture.

  12. Synchronously pumped nuclear magnetic oscillator

    NASA Astrophysics Data System (ADS)

    Korver, Anna; Thrasher, Daniel; Bulatowicz, Michael; Walker, Thad

    2015-05-01

    We present progress towards a synchronously pumped nuclear magnetic oscillator. Alkali frequency shifts and quadrupole shifts are the dominant systematic effects in dual Xe isotope co-magnetometers. By synchronously pumping the Xe nuclei using spin-exchange with an oscillating Rb polarization, the Rb and Xe spins precess transverse to the longitudinal bias field. This configuration is predicted to be insensitive to first order quadrupole interactions and alkali spin-exchange frequency shifts. A key feature that allows co-precession of the Rb and Xe spins, despite a ~ 1000 fold ratio of their gyromagnetic ratios, is to apply the bias field in the form of a sequence of Rb 2 π pulses whose repetition frequency is equal to the Rb Larmor frequency. The 2 π pulses result in an effective Rb magnetic moment of zero, while the Xe precession depends only on the time average of the pulsed field amplitude. Polarization modulation of the pumping light at the Xe NMR frequency allows co-precession of the Rb and Xe spins. We will present our preliminary experimental studies of this new approach to NMR of spin-exchange pumped Xe. Support by the NSF and Northrop Grumman Co.

  13. The international conference on solar energy storage and applied photochemistry

    NASA Astrophysics Data System (ADS)

    1995-01-01

    A bibliography of the international conference on solar energy storage and applied photochemistry is presented. Study areas dicussed include: Nanocrystalline solar cells; scientific principles and economic perspectives; Solar synthesis of hydrogen peroxide; Dye molecules in zeolites as artificial antenna systems; Mechanism of the early steps in photosynthesis; Novel vacuum-uv-(vuv) and uv excimer flow through photorectors for waste water treatment and for wavelengths selective photochemistry; Heterosupramolecular chemistry: an approach to modulating function in molecular devices; Excited state characteristics and new unactivated C-H bond functionalization photocatalysis by W10O32 (4-); Time-resolved photothermal measurements on biological photoreceptors; Photoinduced proton transfer in substituted pyridines; Photochromic materials: a comprehensive kinetic thermodynamic and photochemical study; Photolysis and thermolysis of acid amides and sulphonamides; mechanistic studies; Studies of photochemical reactions by nuclear spin polarization detected ESR spectroscopy; A non-silver dry processed photographic arts film.

  14. Polarization probes of vorticity in heavy ion collisions

    SciTech Connect

    Betz, Barbara; Gyulassy, Miklos; Torrieri, Giorgio

    2007-10-15

    We discuss the information that can be deduced from a measurement of hadron (hyperon or vector meson) polarization in ultrarelativistic nuclear collisions. We describe the sensitivity of polarization to initial conditions, hydrodynamic evolution, and mean free path and find that the polarization observable is sensitive to all details and stages of the system's evolution. We suggest that an experimental investigation covering production plane and reaction plane polarizations, as well as the polarization of jet-associated particles in the plane defined by the jet and particle direction, can help in disentangling the factors contributing to this observable. Scans of polarization in energy and rapidity might also point to a change in the system's properties.

  15. Invited Article: Polarization ``Down Under'': The polarized time-of-flight neutron reflectometer PLATYPUS

    NASA Astrophysics Data System (ADS)

    Saerbeck, T.; Klose, F.; Le Brun, A. P.; Füzi, J.; Brule, A.; Nelson, A.; Holt, S. A.; James, M.

    2012-08-01

    This review presents the implementation and full characterization of the polarization equipment of the time-of-flight neutron reflectometer PLATYPUS at the Australian Nuclear Science and Technology Organisation (ANSTO). The functionality and efficiency of individual components are evaluated and found to maintain a high neutron beam polarization with a maximum of 99.3% through polarizing Fe/Si supermirrors. Neutron spin-flippers with efficiencies of 99.7% give full control over the incident and scattered neutron spin direction over the whole wavelength spectrum available in the instrument. The first scientific experiments illustrate data correction mechanisms for finite polarizations and reveal an extraordinarily high reproducibility for measuring magnetic thin film samples. The setup is now fully commissioned and available for users through the neutron beam proposal system of the Bragg Institute at ANSTO.

  16. Neutron spin structure with polarized deuterons and spectator proton tagging at EIC

    DOE PAGES

    Cosyn, W.; Guzey, V.; Higinbotham, D. W.; Hyde, C.; Kuhn, S.; Nadel-Turonski, P.; Park, K.; Sargsian, M.; Strikman, M.; Weiss, C.

    2014-10-27

    The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Thus, traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x << 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < pR << several 100 MeV in the nucleusmore » rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.« less

  17. Neutron spin structure with polarized deuterons and spectator proton tagging at EIC

    SciTech Connect

    Cosyn, W.; Guzey, V.; Higinbotham, D. W.; Hyde, C.; Kuhn, S.; Nadel-Turonski, P.; Park, K.; Sargsian, M.; Strikman, M.; Weiss, C.

    2014-10-27

    The neutron's deep-inelastic structure functions provide essential information for the flavor separation of the nucleon parton densities, the nucleon spin decomposition, and precision studies of QCD phenomena in the flavor-singlet and nonsinglet sectors. Thus, traditional inclusive measurements on nuclear targets are limited by dilution from scattering on protons, Fermi motion and binding effects, final-state interactions, and nuclear shadowing at x << 0.1. An Electron-Ion Collider (EIC) would enable next-generation measurements of neutron structure with polarized deuteron beams and detection of forward-moving spectator protons over a wide range of recoil momenta (0 < pR << several 100 MeV in the nucleus rest frame). The free neutron structure functions could be obtained by extrapolating the measured recoil momentum distributions to the on-shell point. The method eliminates nuclear modifications and can be applied to polarized scattering, as well as to semi-inclusive and exclusive final states. We review the prospects for neutron structure measurements with spectator tagging at EIC, the status of R&D efforts, and the accelerator and detector requirements.

  18. RHIC Polarized proton operation

    SciTech Connect

    Huang, H.; Ahrens, L.; Alekseev, I.G.; Aschenauer, E.; Atoian, G.; Bai, M.; Bazilevsky, A.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Connolly, R.; Dion, A.; D'Ottavio, T.; Drees, K.A.; Fischer, W.; Gardner, C.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Hulsart, R.L.; Laster, J.; Liu, C.; Luo, Y.; MacKay, W.W.; Makdisi, Y.; Marr, G.J.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R,; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Poblaguev, A.; Ptitsyn, V.; Ranjibar, V.; Robert-Demolaize, G.; Roser, T.; J.; Severino, F.; Schmidke, B.; Schoefer, V.; Severino, F.; Smirnov, D.; Smith, K.; Steski, D.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J. Wang, G.; Wilinski, M.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S.Y.

    2011-03-28

    The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP{sup 4}. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above

  19. Cyclotron-based nuclear science. Progress report, April 1, 1979-March 31, 1980

    SciTech Connect

    Not Available

    1980-06-01

    Research at the cyclotron institute is summarized. These major areas are covered: nuclear structure; nuclear reactions and scattering; polarization studies; interdisciplinary nuclear science; instrumentation and systems development; and publications. (GHT)

  20. Our Polar Past

    ERIC Educational Resources Information Center

    Clary, Renee; Wandersee, James

    2009-01-01

    The study of polar exploration is fascinating and offers students insights into the history, culture, and politics that affect the developing sciences at the farthest ends of Earth. Therefore, the authors think there is value in incorporating polar exploration accounts within modern science classrooms, and so they conducted research to test their…