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Sample records for electrophoretic nmr measurements

  1. Convection Compensated Electrophoretic NMR

    NASA Astrophysics Data System (ADS)

    He, Qiuhong; Wei, Zhaohui

    2001-06-01

    A novel method of convection compensated ENMR (CC-ENMR) has been developed to detect electrophoretic motion of ionic species in the presence of bulk solution convection. This was accomplished using a gradient moment nulling technique to remove spectral artifacts from heat-induced convection and using the polarity switch of the applied electric field to retain spin phase modulations due to electrophoretic flow. Experiments were carried out with a mixture of 100 mM L-aspartic acid and 100 mM 4,9-dioxa-1,12-dodecanediamine to demonstrate this new method of ENMR. CC-ENMR enhances our previously developed capillary array ENMR (CA-ENMR) in solving the convection problem. The combined CA- and CC-ENMR approach strengthens the potential of multidimensional ENMR in simultaneous structural determination of coexisting proteins and protein conformations in biological buffer solutions of high ionic strength. Structural mapping of interacting proteins during biochemical reactions becomes possible in the future using ENMR techniques, which may have a profound impact on the understanding of biological events, including protein folding, genetic control, and signal transduction in general.

  2. On electrophoretic NMR. Exploring high conductivity samples

    NASA Astrophysics Data System (ADS)

    Bielejewski, Michał; Giesecke, Marianne; Furó, István

    2014-06-01

    The performance of a new electrophoretic NMR (eNMR) method that uses a Carr-Purcell-Meiboom-Gill echo train with repeated electric field reversal is investigated. We show that this pulse sequence, with acronym CPMGER, yields strongly reduced artifacts from convective flow effects caused by the simultaneous presence of electroosmotic and thermal driving forces. We demonstrate the achieved improvements in various aqueous solutions. Ultimately, the method can be used for obtaining electrophoretic mobilities by eNMR without relying on uncharged reference molecules, otherwise a significant limitation for electrophoretic experiments performed with nuclei other than 1H.

  3. Sensitive and robust electrophoretic NMR: Instrumentation and experiments

    NASA Astrophysics Data System (ADS)

    Hallberg, Fredrik; Furó, István; Yushmanov, Pavel V.; Stilbs, Peter

    2008-05-01

    Although simple as a concept, electrophoretic NMR (eNMR) has so far failed to find wider application. Problems encountered are mainly due to disturbing and partly irreproducible convection-like bulk flow effects from both electro-osmosis and thermal convection. Additionally, bubble formation at the electrodes and rf noise pickup has constrained the typical sample geometry to U-tube-like arrangements with a small filling factor and a low resulting NMR sensitivity. Furthermore, the sign of the electrophoretic mobility cancels out in U-tube geometries. We present here a new electrophoretic sample cell based on a vertically placed conventional NMR sample tube with bubble-suppressing palladium metal as electrode material. A suitable radiofrequency filter design prevents noise pickup by the NMR sample coil from the high-voltage leads which extend into the sensitive sample volume. Hence, the obtained signal-to-noise ratio of this cell is one order of magnitude higher than that of our previous U-tube cells. Permitted by the retention of the sign of the displacement-related signal phase in the new cell design, an experimental approach is described where bulk flow effects by electro-osmosis and/or thermal convection are compensated through parallel monitoring of a reference signal from a non-charged species in the sample. This approach, together with a CPMG-like pulse train scheme provides a superior first-order cancellation of non-electrophoretic bulk flow effects.

  4. Measurement of deformations by NMR

    NASA Astrophysics Data System (ADS)

    Bytchenkoff, Dimitri; Rodts, Stéphane

    2015-12-01

    Two NMR data acquisition protocols together with corresponding data processing algorithms for locating macroscopic objects, measuring distances between them or monitoring their displacements or deformations with microscopic precision are presented and discussed. The performance of the methods is demonstrated by applying them to the measurement of deformations of a freely supported beam under loading. We believe that our methods will find their applications in mechanics, civil engineering and medicine.

  5. Measurement of vorticity diffusion by NMR microscopy.

    PubMed

    Brown, Jennifer R; Callaghan, Paul T

    2010-05-01

    In a Newtonian fluid, vorticity diffuses at a rate determined by the kinematic viscosity. Here we use rapid NMR velocimetry, based on a RARE sequence, to image the time-dependent velocity field on startup of a fluid-filled cylinder and therefore measure the diffusion of vorticity. The results are consistent with the solution to the vorticity diffusion equation where the angular velocity on the outside surface of the fluid, at the cylinder's rotating wall, is fixed. This method is a means of measuring kinematic viscosity for low viscosity fluids without the need to measure stress. PMID:20189854

  6. NMR measurements in SSC dipole D00001

    SciTech Connect

    Kuchnir, M.; Schmidt, E.E.; Hanft, R.W.; Strait, J.B.

    1986-09-12

    The first 16.5 m long SSC dipole magnet (D00001) had its field intensity measured as a function of position with a custom made NMR magnetometer. A short description of the probe is presented. The data obtained (most of it near 2 T spaced apart by one inch) shows an average transfer function of 1.02830 T/KA with position dependent values deviating from the average by up to .00130 T/KA revealing contruction inhomogeneities that were measured with a sensitivity of 25 ppM.

  7. Using Electrophoretic Mobility Shift Assays to Measure Equilibrium Dissociation Constants: GAL4-p53 Binding DNA as a Model System

    ERIC Educational Resources Information Center

    Heffler, Michael A.; Walters, Ryan D.; Kugel, Jennifer F.

    2012-01-01

    An undergraduate biochemistry laboratory experiment is described that will teach students the practical and theoretical considerations for measuring the equilibrium dissociation constant (K[subscript D]) for a protein/DNA interaction using electrophoretic mobility shift assays (EMSAs). An EMSA monitors the migration of DNA through a native gel;…

  8. Calibration of NMR well logs from carbonate reservoirs with laboratory NMR measurements and μXRCT

    SciTech Connect

    Mason, Harris E.; Smith, Megan M.; Hao, Yue; Carroll, Susan A.

    2014-12-31

    The use of nuclear magnetic resonance (NMR) well log data has the potential to provide in-situ porosity, pore size distributions, and permeability of target carbonate CO₂ storage reservoirs. However, these methods which have been successfully applied to sandstones have yet to be completely validated for carbonate reservoirs. Here, we have taken an approach to validate NMR measurements of carbonate rock cores with independent measurements of permeability and pore surface area to volume (S/V) distributions using differential pressure measurements and micro X-ray computed tomography (μXRCT) imaging methods, respectively. We observe that using standard methods for determining permeability from NMR data incorrectly predicts these values by orders of magnitude. However, we do observe promise that NMR measurements provide reasonable estimates of pore S/V distributions, and with further independent measurements of the carbonate rock properties that universally applicable relationships between NMR measured properties may be developed for in-situ well logging applications of carbonate reservoirs.

  9. NMR Measurements of Granular Flow and Compaction

    NASA Astrophysics Data System (ADS)

    Fukushima, Eiichi

    1998-03-01

    Nuclear magnetic resonance (NMR) can be used to measure statistical distributions of granular flow velocity and fluctuations of velocity, as well as spatial distributions of particulate concentration, flow velocity, its fluctuations, and other parameters that may be derived from these. All measurements have been of protons in liquid-containing particles such as mustard seeds or pharmaceutical pills. Our favorite geometry has been the slowly rotating partially filled rotating drum with granular flow taking place along the free surface of the particles. All the above-mentioned parameters have been studied as well as a spatial distribution of particulate diffusion coefficients, energy dissipation due to collisions, as well as segregation of non-uniform mixtures of granular material. Finally, we describe some motions of granular material under periodic vibrations.

  10. NMR measurements in solutions of dialkylimidazolium haloaluminates

    SciTech Connect

    Takahashi, S.; Saboungi, M.L.; Klingler, R.J.; Chen, M.J.; Rathke, J.W.

    1992-06-01

    {sup 27}Al and {sup 35}Cl NMR spectra of AlCl{sub 3}-1-ethyl-3-methyl imidazolium chloride (EMIC) melts were measured for initial compositions ranging from 50 to 67 mol % AlCl{sub 3} at various temperatures. It was shown by changing the preaquisition delay time (DE value) that the dominant aluminum species are AlCl{sub 4}{sup {minus}} in the melt formed by mixing 50 mol % with EMIC and Al{sub 2}Cl{sub 7}{sup {minus}} in the 67 mol % AlCl{sub 3} melt. In the equimolar mixture, the chemical shift of {sup 27}Al NMR spectrum is 103.28 ppm and the line width is 22.83Hz. In the 67 mol % AlCl{sub 3} mixture, the chemical shift is 103.41 ppm and the line width is 2624Hz. A third species observed at 97 ppm in the {sup 27}Al spectra for the 55 and 60 mol % AlCl{sub 3} mixtures is identified to be a product of the reaction with residual water. The relaxation rates for each species in the melts were determined.

  11. Easy measurement and analysis method of zeta potential and electrophoretic mobility of water-dispersed colloidal particles by using a self-mixing solid-state laser

    NASA Astrophysics Data System (ADS)

    Sudo, S.; Ohtomo, T.; Otsuka, K.

    2013-08-01

    We describe a highly sensitive method of measuring electrophoretic mobility and zeta potential of water-dispersed colloidal particles by using a self-mixing laser Doppler velocimeter with a laser-diode-pumped, thin-slice solid-state laser with extremely high optical sensitivity. The power spectra of laser output modulated by reinjected laser light scattered by the electrophoretic particles were observed. The power spectrum cannot be described by the well-known formula for translational motion or flowing Brownian motion, i.e., a combination of Doppler shift, diffusion, and translation. The power spectra shape is found to reflect the velocity distribution of electrophoretic particles in a capillary tube due to the electro-osmotic flow contribution. Not only evaluation of the electrophoretic mobility and zeta potential but also the particle diameter undergoing electrophoretic motion can be performed from the shape of the power spectrum.

  12. Calibration of NMR well logs from carbonate reservoirs with laboratory NMR measurements and μXRCT

    DOE PAGESBeta

    Mason, Harris E.; Smith, Megan M.; Hao, Yue; Carroll, Susan A.

    2014-12-31

    The use of nuclear magnetic resonance (NMR) well log data has the potential to provide in-situ porosity, pore size distributions, and permeability of target carbonate CO₂ storage reservoirs. However, these methods which have been successfully applied to sandstones have yet to be completely validated for carbonate reservoirs. Here, we have taken an approach to validate NMR measurements of carbonate rock cores with independent measurements of permeability and pore surface area to volume (S/V) distributions using differential pressure measurements and micro X-ray computed tomography (μXRCT) imaging methods, respectively. We observe that using standard methods for determining permeability from NMR data incorrectlymore » predicts these values by orders of magnitude. However, we do observe promise that NMR measurements provide reasonable estimates of pore S/V distributions, and with further independent measurements of the carbonate rock properties that universally applicable relationships between NMR measured properties may be developed for in-situ well logging applications of carbonate reservoirs.« less

  13. Increasing the quantitative bandwidth of NMR measurements.

    PubMed

    Power, J E; Foroozandeh, M; Adams, R W; Nilsson, M; Coombes, S R; Phillips, A R; Morris, G A

    2016-02-18

    The frequency range of quantitative NMR is increased from tens to hundreds of kHz by a new pulse sequence, CHORUS. It uses chirp pulses to excite uniformly over very large bandwidths, yielding accurate integrals even for nuclei such as (19)F that have very wide spectra. PMID:26789115

  14. Electrophoretic Focusing

    NASA Technical Reports Server (NTRS)

    Snyder, Robert S.

    2001-01-01

    Electrophoretic focusing is a new method of continuous flow electrophoresis that introduces precision flow control to achieve high resolution separations. The electric field is applied perpendicular to an incoming sample lamina and buffer but also perpendicular to the broad faces of the thin rectangular chamber. A uniform fluid cross-flow then enters and exits the separation chamber through the same broad faces which are porous. A balance is achieved by adjusting either the electric field or the cross-flow so the desired sample fraction with its specific migration velocity encounters an opposing flow of the same velocity. Applying an electric field transverse to the incoming sample lamina and opposing this field with a carefully configured buffer flow, a sample constituent can be selected and focused into a narrow stream for subsequent analysis. Monotonically changing either electric field or buffer cross-flow will yield a scan of all constituents of the sample. Stopping the scan increases the collection time for minor constituents to improve their analysis. Using the high voltage gradients and/or cross-flow to rapidly deflect extraneous sample through the porous screens and into either of the side (purge) chambers, the selected sample is focused in the center plane of the separation chamber and collected without contact or interaction with the separation chamber walls. Results will be presented on the separation of a range of materials including dyes, proteins, and monodisperse polystyrene latexes. Sources of sample dispersion inherent in other electrokinetic techniques will be shown to be negligible for a variety of sample concentrations, buffer properties and operating conditions.

  15. Characterization of the Cell Surface Properties of Drinking Water Pathogens by Microbial Adhesion to Hydrocarbon and Electrophoretic Mobility Measurements

    EPA Science Inventory

    The surface characteristics of microbial cells directly influence their mobility and behavior within aqueous environments. The cell surface hydrophobicity (CSH) and electrophoretic mobility (EPM) of microbial cells impact a number of interactions and processes including aggregati...

  16. Characterization of the cell surface properties of drinking water pathogens by microbial adhesion to hydrocarbon and electrophoretic mobility measurements.

    PubMed

    Popovici, Jonathan; White, Colin P; Hoelle, Jill; Kinkle, Brian K; Lytle, Darren A

    2014-06-01

    The surface characteristics of microbial cells directly influence their mobility and behavior within aqueous environments. The cell surface hydrophobicity (CSH) and electrophoretic mobility (EPM) of microbial cells impact a number of interactions and processes including aggregation, adhesion to surfaces, and stability of the cells within the aqueous environments. These cell characteristics are unique to the bacterial species and are a reflection of the large diversity of surface structures, proteins, and appendages of microorganisms. CSH and EPM of bacterial cells contribute substantially to the effectiveness of drinking water treatment to remove them, and therefore an investigation of these properties will be useful in predicting their removal through drinking water treatment processes and transport through drinking water distribution systems. EPM and CSH measurements of six microbiological pathogen or surrogate species suspended in phosphate-buffered water are reported in this work. Two strains of Vibrio cholerae were hydrophobic, while three strains of Escherichia coli were hydrophilic. Bacillus cereus was categorized as moderately hydrophobic. The strains of E. coli had the highest (most negative) EPM. Based on the measurements, E. coli species is predicted to be most difficult to remove from water while V. cholerae will be the easiest to remove. PMID:24815929

  17. Improvements in Technique of NMR Imaging and NMR Diffusion Measurements in the Presence of Background Gradients.

    NASA Astrophysics Data System (ADS)

    Lian, Jianyu

    In this work, modification of the cosine current distribution rf coil, PCOS, has been introduced and tested. The coil produces a very homogeneous rf magnetic field, and it is inexpensive to build and easy to tune for multiple resonance frequency. The geometrical parameters of the coil are optimized to produce the most homogeneous rf field over a large volume. To avoid rf field distortion when the coil length is comparable to a quarter wavelength, a parallel PCOS coil is proposed and discussed. For testing rf coils and correcting B _1 in NMR experiments, a simple, rugged and accurate NMR rf field mapping technique has been developed. The method has been tested and used in 1D, 2D, 3D and in vivo rf mapping experiments. The method has been proven to be very useful in the design of rf coils. To preserve the linear relation between rf output applied on an rf coil and modulating input for an rf modulating -amplifying system of NMR imaging spectrometer, a quadrature feedback loop is employed in an rf modulator with two orthogonal rf channels to correct the amplitude and phase non-linearities caused by the rf components in the rf system. The modulator is very linear over a large range and it can generate an arbitrary rf shape. A diffusion imaging sequence has been developed for measuring and imaging diffusion in the presence of background gradients. Cross terms between the diffusion sensitizing gradients and background gradients or imaging gradients can complicate diffusion measurement and make the interpretation of NMR diffusion data ambiguous, but these have been eliminated in this method. Further, the background gradients has been measured and imaged. A dipole random distribution model has been established to study background magnetic fields Delta B and background magnetic gradients G_0 produced by small particles in a sample when it is in a B_0 field. From this model, the minimum distance that a spin can approach a particle can be determined by measuring

  18. Zeta potential determination by streaming current modelization and measurement in electrophoretic microfluidic systems.

    PubMed

    Renaud, Louis; Kleimann, Pascal; Morin, Pierre

    2004-01-01

    Electrophoresis in capillary and microfluidic systems, used in analytical chemistry to separate charged species, are quite sensitive to surface phenomena in terms of separation performances. In order to improve theses performances, new surface functionalization techniques are required. There is a need for methods to provide fast and accurate quantification about surface charges at liquid/solid interfaces. We present a fast, simple, and low-cost technique for the measurement of the zeta-potential, via the modelization and the measurement of streaming currents. Due to the small channel cross section in microfluidic devices, the streaming current modelization is easier than the streaming potential measurement. The modelization combines microfluidic simulations based on the Navier-Stokes equation and charge repartition simulations based on the Poisson-Boltzmann equation. This method has been validated with square and circular cross section shape fused-silica capillaries and can be easily transposed to any lab-on-chip microsystems. PMID:14730576

  19. Development and Characterization of NMR Measurements for Polymer Gel Dosimetry

    NASA Astrophysics Data System (ADS)

    Kwong, Zachary; Whitney, Heather

    2012-03-01

    Polymer gel dosimeters are systems of water, gelatin, and monomers which form polymers upon irradiation. The gelatin matrix retains dose distribution in 3D form, facilitating truly integrated measurements of complex dose plans for radiation therapy. Polymer gels have two proton pools coupled by exchange: free solvent protons and bound polymerized macromolecular protons. Measuring magnetization transfer (MT) and relaxation affords useful insights into particle rigidity and chemical exchange effects on relaxation in polymer gels. Polymer gel dose response has been previously quantified with several techniques, most often in terms of MRI parameters, usually at field strengths of 1.5 T and below. The research described here investigates the dose response of a revised MAGIC gel dosimeter via both high-field imaging and simpler nuclear magnetic resonance (NMR) spectroscopy. This includes both transverse and longitudinal relaxation rates (R2 and R1) and quantitative MT parameters. We investigated estimating polymer molecular weight for a given applied dose using the Rouse model and R2 data from the imaging study. Finally, we began development of NMR methods for studying dose response, requiring adaption of NMR experiments to accommodate for radiation damping.

  20. NMR temperature measurements using a paramagnetic lanthanide complex.

    PubMed

    Zuo, C S; Metz, K R; Sun, Y; Sherry, A D

    1998-07-01

    NMR thermometry has previously suffered from poor thermal resolution owing to the relatively weak dependence of chemical shift on temperature in diamagnetic molecules. In contrast, the shifts of nuclear spins near a paramagnetic center exhibit strong temperature dependencies. The chemical shifts of the thulium 1,4,7, 10-tetraazacyclododecane-1,4,7,10-tetrakis(methylene phosphonate) complex (TmDOTP5-) have been studied as a function of temperature, pH, and Ca2+ concentration over ranges which may be encountered in vivo. The results demonstrate that the 1H and 31P shifts in TmDOTP5- are highly sensitive to temperature and may be used for NMR thermometry with excellent accuracy and resolution. A new technique is also described which permits simultaneous measurements of temperature and pH changes from the shifts of multiple TmDOTP5- spectral lines. PMID:9654468

  1. Rheo-NMR Measurements of Cocoa Butter Crystallized Under

    SciTech Connect

    Mudge, E.; Mazzanti, G

    2009-01-01

    Modifications of a benchtop NMR instrument were made to apply temperature control to a shearing NMR cell. This has enabled the determination in situ of the solid fat content (SFC) of cocoa butter under shearing conditions. The cocoa butter was cooled at 3 C/min to three final temperatures of 17.5, 20.0, and 22.5 C with applied shear rates between 45 and 720 s-1. Polymorphic transitions of the cocoa butter were determined using synchrotron X-ray diffraction with an identical shearing system constructed of Lexan. Sheared samples were shown to have accelerated phase transitions compared to static experiments. In experiments where form V was confirmed to be the dominant polymorph, the final SFC averaged around 50%. However, when other polymorphic forms were formed, a lower SFC was measured because the final temperature was within the melting range of that polymorph and only partial crystallization happened. A shear rate of 720 s-1 delayed phase transitions, likely due to viscous heating of the sample. Pulsed NMR is an invaluable tool for determining the crystalline fraction in hydrogen containing materials, yet its use for fundamental and industrial research on fat or alkanes crystallization under shear has only recently been developed.

  2. Improved spin-echo-edited NMR diffusion measurements.

    PubMed

    Otto, W H; Larive, C K

    2001-12-01

    The need for simple and robust schemes for the analysis of ligand-protein binding has resulted in the development of diffusion-based NMR techniques that can be used to assay binding in protein solutions containing a mixture of several ligands. As a means of gaining spectral selectivity in NMR diffusion measurements, a simple experiment, the gradient modified spin-echo (GOSE), has been developed to reject the resonances of coupled spins and detect only the singlets in the (1)H NMR spectrum. This is accomplished by first using a spin echo to null the resonances of the coupled spins. Following the spin echo, the singlet magnetization is flipped out of the transverse plane and a dephasing gradient is applied to reduce the spectral artifacts resulting from incomplete cancellation of the J-coupled resonances. The resulting modular sequence is combined here with the BPPSTE pulse sequence; however, it could be easily incorporated into any pulse sequence where additional spectral selectivity is desired. Results obtained with the GOSE-BPPSTE pulse sequence are compared with those obtained with the BPPSTE and CPMG-BPPSTE experiments for a mixture containing the ligands resorcinol and tryptophan in a solution of human serum albumin. PMID:11740906

  3. Characterization of U(VI)-carbonato ternary complexes on hematite: EXAFS and electrophoretic mobility measurements

    USGS Publications Warehouse

    Bargar, John R.; Reitmeyer, Rebecca; Lenhart, John J.; Davis, James A.

    2000-01-01

    We have measured U(VI) adsorption on hematite using EXAFS spectroscopy and electrophoresis under conditions relevant to surface waters and aquifers (0.01 to 10 μM dissolved uranium concentrations, in equilibrium with air, pH 4.5 to 8.5). Both techniques suggest the existence of anionic U(VI)-carbonato ternary complexes. Fits to EXAFS spectra indicate that U(VI) is simultaneously coordinated to surface FeO6 octahedra and carbonate (or bicarbonate) ligands in bidentate fashions, leading to the conclusion that the ternary complexes have an inner-sphere metal bridging (hematite-U(VI)-carbonato) structure. Greater than or equal to 50% of adsorbed U(VI) was comprised of monomeric hematite-U(VI)-carbonato ternary complexes, even at pH 4.5. Multimeric U(VI) species were observed at pH ≥ 6.5 and aqueous U(VI) concentrations approximately an order of magnitude more dilute than the solubility of crystalline β-UO2(OH)2. Based on structural constraints, these complexes were interpreted as dimeric hematite-U(VI)-carbonato ternary complexes. These results suggest that Fe-oxide-U(VI)-carbonato complexes are likely to be important transport-limiting species in oxic aquifers throughout a wide range of pH values.

  4. Two Phase Flow Measurements by Nuclear Magnetic Resonance (NMR)

    SciTech Connect

    Altobelli, Stephen A; Fukushima, Eiichi

    2006-08-14

    In concentrated suspensions, there is a tendency for the solid phase to migrate from regions of high shear rate to regions of low shear (Leighton & Acrivos, 1987). In the early years that our effort was funded by the DOE Division of Basic Energy Science, quantitative measurement of this process in neutrally buoyant suspensions was a major focus (Abbott, et al., 1991; Altobelli, et al., 1991). Much of this work was used to improve multi-phase numerical models at Sandia National Laboratories. Later, our collaborators at Sandia and the University of New Mexico incorporated body forces into their numerical models of suspension flow (Rao, Mondy, Sun, et al., 2002). We developed experiments that allow us to study flows driven by buoyancy, to characterize these flows in well-known and useful engineering terms (Altobelli and Mondy, 2002) and to begin to explore the less well-understood area of flows with multiple solid phases (Beyea, Altobelli, et al., 2003). We also studied flows that combine the effects of shear and buoyancy, and flows of suspensions made from non-Newtonian liquids (Rao, Mondy, Baer, et al, 2002). We were able to demonstrate the usefulness of proton NMR imaging of liquid phase concentration and velocity and produced quantitative data not obtainable by other methods. Fluids flowing through porous solids are important in geophysics and in chemical processing. NMR techniques have been widely used to study liquid flow in porous media. We pioneered the extension of these studies to gas flows (Koptyug, et al, 2000, 2000, 2001, 2002). This extension allows us to investigate a wider range of Peclet numbers, and to gather data on problems of interest in catalysis. We devised two kinds of NMR experiments for three-phase systems. Both experiments employ two NMR visible phases and one phase that gives no NMR signal. The earlier method depends on the two visible phases differing in a NMR relaxation property. The second method (Beyea, Altobelli, et al., 2003) uses two

  5. Electrical transport in a disordered medium: NMR measurement of diffusivity and electrical mobility of ionic charge carriers.

    PubMed

    Heil, S R; Holz, M

    1998-11-01

    Electrical transport in porous media plays an important role in many fields of pure and applied science. The basic microscopic processes of the charge transport have attracted considerable theoretical interest for a long time. However, on a microscopic level there was up to now no experimental access to this problem. In the present paper we demonstrate, by using a suited porous system, that two combined NMR methods can offer such a first experimental access. We apply common PFG NMR methods and the special electrophoretic NMR (ENMR) technique for the measurement of self-diffusion coefficient D+ and electric mobility u+ of a cation ((C4H9)+4) in a disordered gel-like medium (Sephadex LH-20) filled with electrolyte solution. We find a, qualitatively expected, observation time-dependence of D+, but for the first time such a time-dependence is also observed for u+, which means the detection of the phenomenon of "anomalous field assisted diffusion" or "anomalous mobility." For the measurement of the short-time behavior of the mobility a new pulse sequence is presented. The time-dependent mobilities were measured at three different external electrical fields E. From the long-time behavior of D+, u+, and DH2O three independent values for the tortuosity T of the porous system could be derived. We find equality of the tortuosities T(D+) and T(u+), which represents a first experimental proof of the validity of the Einstein relation (D+ approximately u+) in a disordered medium. Finally, we discuss advantages of the possible use of "anomalous field assisted diffusion" over the commonly used "anomalous diffusion" in morphology studies by dynamic imaging in porous media. PMID:9799669

  6. Xenon NMR measurements of permeability and tortuosity in reservoir rocks.

    PubMed

    Wang, Ruopeng; Pavlin, Tina; Rosen, Matthew Scott; Mair, Ross William; Cory, David G; Walsworth, Ronald Lee

    2005-02-01

    In this work we present measurements of permeability, effective porosity and tortuosity on a variety of rock samples using NMR/MRI of thermal and laser-polarized gas. Permeability and effective porosity are measured simultaneously using MRI to monitor the inflow of laser-polarized xenon into the rock core. Tortuosity is determined from measurements of the time-dependent diffusion coefficient using thermal xenon in sealed samples. The initial results from a limited number of rocks indicate inverse correlations between tortuosity and both effective porosity and permeability. Further studies to widen the number of types of rocks studied may eventually aid in explaining the poorly understood connection between permeability and tortuosity of rock cores. PMID:15833638

  7. Calibrating NMR measured porosity/permeability relationships using µXRCT measurements

    NASA Astrophysics Data System (ADS)

    Mason, H. E.; Smith, M. M.; Hao, Y.; Carroll, S.

    2015-12-01

    Carbonate reservoirs have garnered interest for potential use in carbon capture and storage (CCS) activities. To be suitable for long term carbon dioxide (CO2) storage, they must possess sufficient permeability either through existing connected pore space, or due to reactivity with CO2-acidified fluids. Adequate assessment of the target formation permeability will rely on accurate downhole well-logging tools. Primary among these tools is nuclear magnetic resonance (NMR) well-logging. Application of this tool relies on our ability to relate the porosity and pore distributions measured by NMR to permeability. These methods are challenging to apply in carbonate reservoirs with complex mineralogies where pores sizes often span orders of magnitudes. We have assessed the ability of NMR methods to measure permeability using rocks from the Weyburn-Midale CO2 Monitoring and Storage Project Saskatchewan, Canada and the Arbuckle injection zone at the Wellington CO2 storage demonstration site, Kansas. Results of laboratory measured permeability values of these rocks indicate that the standard NMR methods for predicting permeability values can produce values off by orders of magnitude within the same flow units. In this presentation, we present the results of a combined NMR and micro X-ray computed tomography (μXRCT) study of these rock cores to better estimate downhole permeability values of carbonate rocks. The results of the study suggest that the dramatic differences in predicted permeability values derive from large differences in the matrix porosity, pore network tortuosities, and mineralogy of the various rock units. We will present new laboratory measurements, and methodologies aimed at producing a universal NMR calibration procedure for determining permeability in carbonate reservoirs. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  8. Large-Scale NMR Measurements in Porous Media

    NASA Astrophysics Data System (ADS)

    Legchenko, Anatoly; Vouillamoz, Jean-Michel

    2011-03-01

    The large-scale Nuclear Magnetic Resonance measurements in the Earth's magnetic field (Surface NMR method) is a geophysical technique that allows non-invasive investigations of water-saturated rocks. The measuring setup consists of a wire loop on the surface that is energized by one or two pulses of oscillating current. After the pulses are cut off, the free induction decay (FID) and/or the spin echo (SE) signal from groundwater could be measured. SNMR results are averaged over the investigated volume that depends on the loop size and typically varies from 20x20x20 to 100x100x100 cubic meters. The maximum depth of groundwater detection can vary from 45 to 150 m depending on measurement conditions, although an average depth of investigation is generally considered to be about 100 m. Our recent results show that combination of FID and SE allows rendering the SNMR less dependent on the geological conditions. Because of different scales, use of rock samples for calibration of the SNMR-estimate of the water content is difficult or impossible. Thus, for interpretation of experimental data we use a mathematical model that allows computing the theoretical signal generated by groundwater. The processing of SNMR data can provide the depth, thickness and water content of investigated aquifers. For improving accuracy of the SNMR results we use calibration based on borehole pumping test data. Based on the water content and the relaxation time provided by MRS it is possible to estimate the aquifer's hydrodynamic properties.

  9. Measurement of Electrophoretic Mobility of Human Promyelocytic Leukemia Cell Lines (HL60) During Neutrophil Differentiation Using On-Chip Cell Electrophoresis

    NASA Astrophysics Data System (ADS)

    Matsuhashi, Ryutaro; Akagi, Takanori; Ichiki, Takanori

    Electrophoretic mobility (EPM) of human promyelocytic leukemia cell lines (HL60) during neutrophil differentiation induced by all-trans retinoic acid (ATRA) or dimethyl sulfoxide (DMSO) was measured using microcapillary electrophoresis chips. Prior to EPM measurement of HL60 cells, neutrophil differentiation of the cells was confirmed by morphological classification. Subsequently, EPM of HL60 cells was measured using an on-chip cell electrophoresis system before and after neutrophil differentiation. The EPM changed gradually with the progress of the neutrophil differentiation. From the analysis of experimental data by principal component analysis, it was revealed that there is a strong correlation between morphologic classification and EPM during the neutrophilic differentiation. The present result suggests that on-chip EPM measurement system can be used as a monitoring tool for the cell differentiation.

  10. Novel Techniques for Pulsed Field Gradient NMR Measurements

    NASA Astrophysics Data System (ADS)

    Brey, William Wallace

    Pulsed field gradient (PFG) techniques now find application in multiple quantum filtering and diffusion experiments as well as in magnetic resonance imaging and spatially selective spectroscopy. Conventionally, the gradient fields are produced by azimuthal and longitudinal currents on the surfaces of one or two cylinders. Using a series of planar units consisting of azimuthal and radial current elements spaced along the longitudinal axis, we have designed gradient coils having linear regions that extend axially nearly to the ends of the coil and to more than 80% of the inner radius. These designs locate the current return paths on a concentric cylinder, so the coils are called Concentric Return Path (CRP) coils. Coils having extended linear regions can be made smaller for a given sample size. Among the advantages that can accrue from using smaller coils are improved gradient strength and switching time, reduced eddy currents in the absence of shielding, and improved use of bore space. We used an approximation technique to predict the remaining eddy currents and a time-domain model of coil performance to simulate the electrical performance of the CRP coil and several reduced volume coils of more conventional design. One of the conventional coils was designed based on the time-domain performance model. A single-point acquisition technique was developed to measure the remaining eddy currents of the reduced volume coils. Adaptive sampling increases the dynamic range of the measurement. Measuring only the center of the stimulated echo removes chemical shift and B_0 inhomogeneity effects. The technique was also used to design an inverse filter to remove the eddy current effects in a larger coil set. We added pulsed field gradient and imaging capability to a 7 T commercial spectrometer to perform neuroscience and embryology research and used it in preliminary studies of binary liquid mixtures separating near a critical point. These techniques and coil designs will find

  11. Method and apparatus for measuring the NMR spectrum of an orientationally disordered sample

    DOEpatents

    Pines, Alexander; Samoson, Ago

    1990-01-01

    An improved NMR probe and method are described which substantially improve the resolution of NMR measurements made on powdered or amorphous or otherwise oreintationally disordered samples. The apparatus mechanically varies the orientation of the sample such that the time average of two or more sets of spherical harmonic functions is zero.

  12. Method and sample spinning apparatus for measuring the NMR spectrum of an orientationally disordered sample

    DOEpatents

    Pines, Alexander; Samoson, Ago

    1990-01-01

    An improved NMR apparatus and method are described which substantially improve the resolution of NMR measurements made on powdered or amorphous or otherwise orientationally disordered samples. The apparatus spins the sample about an axis. The angle of the axis is mechanically varied such that the time average of two or more Legendre polynomials are zero.

  13. Measuring Level Alignment at the Metal–Molecule Interface by In Situ Electrochemical 13C NMR

    SciTech Connect

    Li, Ying; Zelakiewicz, Brian S.; Allison, Thomas C.; Tong, Yu ye J.

    2015-03-16

    A new technique to measure energy-level alignment at a metal–molecule interface between the Fermi level of the metal and the frontier orbitals of the molecule is proposed and experimentally demonstrated. The method, which combines the electrochemistry of organo-ligand-stabilized Au nanoparticles with 13C NMR spectroscopy (i.e. in situ electrochemical NMR), enables measuring both occupied and unoccupied states.

  14. Cerebral blood flow measured by NMR indicator dilution in cats

    SciTech Connect

    Ewing, J.R.; Branch, C.A.; Helpern, J.A.; Smith, M.B.; Butt, S.M.; Welch, K.M.

    1989-02-01

    We developed techniques to assess the utility of a nuclear magnetic resonance (NMR) indicator for cerebral blood flow studies in cats, using Freon-22 for the first candidate. A PIN-diode-switched NMR experiment allowed the acquisition of an arterial as well as a cerebral fluorine-19 signal proportional to concentration vs. time in a 1.89 T magnet. Mean +/- SD blood:brain partition coefficients for Freon-22 were estimated at 0.93 +/- 0.08 for gray matter and 0.77 +/- 0.12 for white matter. Using maximum-likelihood curve fitting, estimates of mean +/- SD resting cerebral blood flow were 50 +/- 19 ml/100 g-min for gray matter and 5.0 +/- 2.0 ml/100 g-min for white matter. Hypercapnia produced the expected increases in gray and white matter blood flow. The physiologic effects of Freon-22, including an increase in cerebral blood flow itself with administration of 40% by volume, may limit its use as an indicator. Nevertheless, the NMR techniques described demonstrate the feasibility of fluorine-19-labeled compounds as cerebral blood flow indicators and the promise for their use in humans.

  15. Multistage Electrophoretic Separators

    NASA Technical Reports Server (NTRS)

    Thomas, Nathan; Doyle, John F.; Kurk, Andy; Vellinger, John C.; Todd, Paul

    2006-01-01

    A multistage electrophoresis apparatus has been invented for use in the separation of cells, protein molecules, and other particles and solutes in concentrated aqueous solutions and suspensions. The design exploits free electrophoresis but overcomes the deficiencies of prior free-electrophoretic separators by incorporating a combination of published advances in mathematical modeling of convection, sedimentation, electro-osmotic flow, and the sedimentation and aggregation of droplets. In comparison with other electrophoretic separators, these apparatuses are easier to use and are better suited to separation in relatively large quantities characterized in the art as preparative (in contradistinction to smaller quantities characterized in the art as analytical). In a multistage electrophoretic separator according to the invention, an applied vertical steady electric field draws the electrically charged particles of interest from within a cuvette to within a collection cavity that has been moved into position of the cuvette. There are multiple collection cavities arranged in a circle; each is aligned with the cuvette for a prescribed short time. The multistage, short-migration-path character of the invention solves, possibly for the first time, the fluid-instability problems associated with free electrophoresis. The figure shows a prototype multistage electrophoretic separator that includes four sample stations and five collection stages per sample. At each sample station, an aqueous solution or suspension containing charged species to be separated is loaded into a cuvette, which is machined into a top plate. The apparatus includes a lower plate, into which 20 collection cavities have been milled. Each cavity is filled with an electrophoresis buffer solution. For the collection of an electrophoretic fraction, the lower plate is rotated to move a designated collection cavity into alignment with the opening of the cuvette. An electric field is then applied between a non

  16. NMR relaxometry measurements of Fricke gel dosimeters exposed to neutrons

    NASA Astrophysics Data System (ADS)

    Marrale, Maurizio; Brai, Maria; Longo, Anna; Gallo, Salvatore; Tomarchio, Elio; Tranchina, Luigi; Gagliardo, Cesare; D'Errico, Francesco

    2014-11-01

    Fricke infused gel matrices offer several features making them suitable for dosimetric applications; among these there are tissue equivalence, low cost and ease of preparation. Their nuclear magnetic resonance (NMR) relaxation properties can be used as a radiation detector for the dosimetry of beams used in cancer therapy. In recent years neutron capture therapy has been resumed for the treatment of various types of cancer and it requires three-dimensional mapping of the neutron fields. In this work, we investigated this particular application through NMR relaxometry and MR imaging of Fricke gels exposed to neutrons. We analyzed both the R1 and R2 relaxation rates, which relate to the longitudinal T1 and transversal T2 relaxation times. In particular, we found that the relaxation rate R2 does not depend on the neutron fluence, whereas the relaxation rate R1 increases linearly with the fluence. The magnetic resonance imaging acquisitions showed that T1-weighted images allow the characterization of samples exposed to different neutron fluences.

  17. Performance evaluation of quantitative adiabatic (13)C NMR pulse sequences for site-specific isotopic measurements.

    PubMed

    Thibaudeau, Christophe; Remaud, Gérald; Silvestre, Virginie; Akoka, Serge

    2010-07-01

    (2)H/(1)H and (13)C/(12)C site-specific isotope ratios determined by NMR spectroscopy may be used to discriminate pharmaceutically active ingredients based on the synthetic process used in production. Extending the Site-specific Natural Isotope Fractionation NMR (SNIF-NMR) method to (13)C is highly beneficial for complex organic molecules when measurements of (2)H/(1)H ratios lead to poorly defined molecular fingerprints. The current NMR methodology to determine (13)C/(12)C site-specific isotope ratios suffers from poor sensitivity and long experimental times. In this work, several NMR pulse sequences based on polarization transfer were evaluated and optimized to measure precise quantitative (13)C NMR spectra within a short time. Adiabatic 180 degrees (1)H and (13)C pulses were incorporated into distortionless enhancement by polarization transfer (DEPT) and refocused insensitive nuclei enhanced by polarization transfer (INEPT) to minimize the influence of 180 degrees pulse imperfections and of off-resonance effects on the precision of the measured (13)C peak areas. The adiabatic DEPT sequence was applied to draw up a precise site-specific (13)C isotope profile of ibuprofen. A modified heteronuclear cross-polarization (HCP) experiment featuring (1)H and (13)C spin-locks with adiabatic 180 degrees pulses is also introduced. This sequence enables efficient magnetization transfer across a wide (13)C frequency range although not enough for an application in quantitative (13)C isotopic analysis. PMID:20527737

  18. Thin film NMR T1 measurement by MRFM using cyclic adiabatic inversion

    NASA Astrophysics Data System (ADS)

    Kwon, Sungmin; Saun, Seung-Bo; Lee, Soonchil; Won, Soonho

    2014-03-01

    We obtained the NMR spectrum and the spin lattice relaxation time (T1) for thin film samples using Magnetic Resonance Force Microscopy (MRFM). The samples were Alq3, which is widely used as an organic light emitting diode (OLED), thin films of 150 nm thick and a bulk crystal. T1 was measured by using the cyclic adiabatic inversion method at a fixed frequency of 297 MHz and at 12 K. To confirm the reliability of our measurement technique we compared the result with that obtained by conventional NMR method. T1 of thin film samples was measured and compared with that of the bulk sample. thin film, MRFM.

  19. ELECTROPHORETIC MOBILITY OF MYCOBACTERIUM AVIUM COMPLEX ORGANISMS

    EPA Science Inventory

    The electrophoretic mobilities (EPMs) of thirty Mycobacterium avium Complex (MAC) organisms isolated from clinical and environmental sources were measured in 9.15 mM KH2PO4 buffered water. The EPMs of fifteen clinical isolates ranged from -1.9 to -5.0 µm cm V-1 ...

  20. ELECTROPHORETIC MOBILITY OF MYCOBACTERIUM AVIUM COMPLEX ORGANISMS

    EPA Science Inventory

    The electrophoretic mobilities (EPMs) of thirty Mycobacterium avium Complex (MAC) organisms were measured. The EPMs of fifteen clinical isolates ranged from -1.9 to -5.0 µm cm V-1s-1, and the EPMs of fifteen environmental isolates ranged from -1...

  1. Internal Referencing for ¹³C Position-Specific Isotope Analysis Measured by NMR Spectrometry.

    PubMed

    Bayle, Kevin; Grand, Mathilde; Chaintreau, Alain; Robins, Richard J; Fieber, Wolfgang; Sommer, Horst; Akoka, Serge; Remaud, Gérald S

    2015-08-01

    The intramolecular (13)C composition of a molecule retains evidence relevant to its (bio)synthetic history and can provide valuable information in numerous fields ranging from biochemistry to environmental sciences. Isotope ratio monitoring by (13)C NMR spectrometry (irm-(13)C NMR) is a generic method that offers the potential to conduct (13)C position-specific isotope analysis with a precision better than 1‰. Until now, determining absolute values also required measurement of the global (or bulk) (13)C composition (δ(13)Cg) by mass spectrometry. In a radical new approach, it is shown that an internal isotopic chemical reference for irm-(13)C NMR can be used instead. The strategy uses (1)H NMR to quantify both the number of moles of the reference and of the studied compound present in the NMR tube. Thus, the sample preparation protocol is greatly simplified, bypassing the previous requirement for precise purity and mass determination. The key to accurate results is suppressing the effect of radiation damping in (1)H NMR which produces signal distortion and alters quantification. The methodology, applied to vanillin with dimethylsulfone as an internal standard, has an equivalent accuracy (<1‰) to that of the conventional approach. Hence, it was possible to clearly identify vanillin from different origins based on the (13)C isotopic profiles. PMID:26158226

  2. 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

  3. Squid-based CW NMR system for measuring the magnetization of helium-3 films

    NASA Astrophysics Data System (ADS)

    White, Kevin Spencer

    This thesis describes the design and construction of a SQUID-based CW NMR system together with its application in a study of the two dimensional magnetism of 3He. 3He provides an exemplary system for the study of two-dimensional magnetism. Two-dimensional 3He films of varying coverages may be formed by plating 3He on relatively uniform two-dimensional substrates, such as GTA Grafoil and ZYX graphite substrates. At coverages above approximately 20 atoms/nm. 2 on these substrates, the second layer of 3He exhibits a strong ferromagnetic ordering tendency. The ferromagnetic ordering presents as a rapid onset of measured magnetization that becomes independent of the applied magnetic field as film temperatures approach 1 mK. Very low applied magnetic fields are used to probe the ferromagnetic ordering in order to minimize masking of the measured magnetization and to stay within the available bandwidth of the SQUID. Commensurate with the ferromagnetic ordering, the NMR linewidth increases dramatically at these coverages and temperatures. An increasing linewidth equates to a short decay time with respect to pulsed NMR probing of the two-dimensional 3He magnetization. The decay times at these coverages and temperatures become so short that they fall below the minimum recovery time necessary for a SQUID-based pulsed NMR system to recover from the relatively large tipping pulse and acquire meaningful data. To address this problem, we have designed a SQUID-based CW NMR system to leverage as much of an already-existing pulsed NMR system as possible but allow accurate measurement of the rapid onset of ferromagnetic ordering of the 3He films below the approximate 1 mK temperature limit of the pulsed NMR system.

  4. Borehole measurement of NMR characteristics of earth formations

    SciTech Connect

    Kleinberger, R.L.; Griffin, D.D.; Fukuhara, M.; Sezginer, A.

    1991-10-08

    This paper describes an apparatus for investigating a characteristic of earth formation traversed by a borehole, comprising a body adapted for longitudinal movement in the borehole. It comprises: first means for producing a static and substantially homogeneous magnetic field in a volume of the formation directed to one side of the body; second means for radiating the volume of formation with oscillating magnetic fields and for detecting signals representative of nuclear magnetic precession of a population of particles in the formation, the second means including: antenna means; circuit means for driving the antenna means to produce oscillating magnetic fields at a frequency in the neighborhood of the NMR precession frequency of the population of particles in the volume of the formation; and Q-switching means for rapidly switching the Q value of the antenna means form a very high value to a low value, the Q-switching means comprising a field effect transistor, and optical-electronic means for switching the transistor on and off.

  5. Surface modification of inorganic black particles for electrophoretic display

    NASA Astrophysics Data System (ADS)

    Kim, Sang Deuk; Ahn, Woo Jin; Choi, Hyoung Jin

    2014-11-01

    Inorganic black particles (Black 444) were modified with poly(methyl methacrylate) as a shell material by using dispersion polymerization to improve their dispersion stability in a medium oil for electrophoretic display applications. They were also positively charged with vinylimidazole to enhance their electrophoretic mobility. The morphology and the shape of the composite particles were characterized by using scanning electron microscopy. The thermal properties and the chemical structure of the samples were examined by using thermogravimetric analysis and Fourier-transform infrared spectroscopy, respectively. In addition, the electrophoretic mobility and the zeta-potential of the black444/PMMA/vinylimidazole particles in a dielectric fluid were measured by using optical microscopy and electrophoretic light scattering. With increasing positive charge, the black444/PMMA/vinylimidazole particles showed improved electrophoretic characteristics compared to pristine Black 444.

  6. NMR shift and relaxation measurements in pulsed high-field magnets up to 58T.

    PubMed

    Kohlrautz, J; Reichardt, S; Green, E L; Kühne, H; Wosnitza, J; Haase, J

    2016-02-01

    Nuclear magnetic resonance (NMR) experiments at fields up to 58T in pulsed magnets at the Dresden High Magnetic Field Laboratory are reported. The challenge to resolve NMR shifts in these time-dependent fields is addressed for the first time, and it is shown that this can indeed be accomplished with high precision with an internal reference. As a result, signal averaging is possible during a single magnetic field pulse, but also for multiple pulses. Thus, even very weak signals can in principle be recorded and their shifts can be determined. In a second set of experiments, the measurement of nuclear relaxation is investigated. Using adiabatic inversion with the inherent time dependence of the magnetic field and small-angle inspection, it is shown that relaxation measurements are possible, as well. The shift experiments were performed with (27)Al NMR on a mixture of aluminum metal and a Linde type A zeolite. For the relaxation studies, (27)Al NMR and (69)Ga NMR on the metals aluminum and gallium were preformed, respectively. PMID:26760950

  7. NMR shift and relaxation measurements in pulsed high-field magnets up to 58 T

    NASA Astrophysics Data System (ADS)

    Kohlrautz, J.; Reichardt, S.; Green, E. L.; Kühne, H.; Wosnitza, J.; Haase, J.

    2016-02-01

    Nuclear magnetic resonance (NMR) experiments at fields up to 58 T in pulsed magnets at the Dresden High Magnetic Field Laboratory are reported. The challenge to resolve NMR shifts in these time-dependent fields is addressed for the first time, and it is shown that this can indeed be accomplished with high precision with an internal reference. As a result, signal averaging is possible during a single magnetic field pulse, but also for multiple pulses. Thus, even very weak signals can in principle be recorded and their shifts can be determined. In a second set of experiments, the measurement of nuclear relaxation is investigated. Using adiabatic inversion with the inherent time dependence of the magnetic field and small-angle inspection, it is shown that relaxation measurements are possible, as well. The shift experiments were performed with 27Al NMR on a mixture of aluminum metal and a Linde type A zeolite. For the relaxation studies, 27Al NMR and 69Ga NMR on the metals aluminum and gallium were preformed, respectively.

  8. Combining SIP and NMR Measurements to Develop Improved Estimates of Permeability in Sandstone Cores

    NASA Astrophysics Data System (ADS)

    Keating, K.; Binley, A. M.

    2013-12-01

    Permeability is traditionally measured in-situ by inducing groundwater flow using pumping, slug, or packer tests; however, these methods require the existence of wells, can be labor intensive and can be constrained by measurement support volumes. Indirect estimates of permeability based on geophysical techniques benefit from relatively short measurement times, do not require fluid extraction, and are non-invasive when made from the surface (or minimally invasive when made in a borehole). However, estimates of permeability based on a single geophysical method often require calibration for rock type, and cannot be used to uniquely determine all of the physical properties required to accurately determine permeability. In this laboratory study we present the first critical step towards developing a method for estimating permeability based on the synergistic coupling of two complementary geophysical methods: spectral induced polarization (SIP) and nuclear magnetic resonance (NMR). To develop an improved model for estimating permeability, laboratory SIP and NMR measurements were collected on a series of sandstone cores, covering a wide range of permeabilities. Current models for estimating permeability from each individual geophysical measurement were compared to independently obtained estimates of permeability. The comparison confirmed previous research showing that estimates from SIP or NMR alone only yield the permeability within order of magnitude accuracy and must be calibrated for rock type. Next, the geophysical parameters determined from SIP and NMR were compared to independent measurements the physical properties of the sandstone cores including gravimetric porosity and pores-size distributions (obtained from mercury injection porosimetry); this comparison was used to evaluate which geophysical parameter more consistently and accurately predicted each physical property. Finally, we present an improved method for estimating permeability in sandstone cores based

  9. Permeability estimation from NMR diffusion measurements in reservoir rocks.

    PubMed

    Balzarini, M; Brancolini, A; Gossenberg, P

    1998-01-01

    It is well known that in restricted geometries, such as in porous media, the apparent diffusion coefficient (D) of the fluid depends on the observation time. From the time dependence of D, interesting information can be derived to characterise geometrical features of the porous media that are relevant in oil industry applications. In particular, the permeability can be related to the surface-to-volume ratio (S/V), estimated from the short time behaviour of D(t), and to the connectivity of the pore space, which is probed by the long time behaviour of D(t). The stimulated spin-echo pulse sequence, with pulsed magnetic field gradients, has been used to measure the diffusion coefficients on various homogeneous and heterogeneous sandstone samples. It is shown that the petrophysical parameters obtained by our measurements are in good agreement with those yielded by conventional laboratory techniques (gas permeability and electrical conductivity). Although the diffusing time is limited by T1, eventually preventing an observation of the real asymptotic behaviour, and the surface-to-volume ratio measured by nuclear magnetic resonance is different from the value obtained by BET because of the different length scales probed, the measurement remains reliable and low-time consuming. PMID:9803918

  10. [A new system using NMR technology for measurement of body composition in experimental animals].

    PubMed

    Suzuki, Jun; Furutoh, Kenichi; Nishikibe, Masaru

    2004-04-01

    Measurement of body composition (fat mass) is an important item in pathophysiological and pharmacological studies using small animals (mice) in the fields of obesity and diabetes. The existing methods are, however, difficult, time consuming, and require a shielding facility. Now a novel system using nuclear magnetic resonance (NMR) technique was developed for measurement of body composition in small animals (mice) that provides noninvasive and rapid measurement without anesthetics; we introduced and evaluated this system and tried another application of this system. First, we validated this system using canola oil, soft tissues (adipose and skeletal muscle), and various kinds of rodent chows. Accuracy, precision, and reproducibility of this system were demonstrated to be equal to those in standard chemical methods. A strong positive correlation (y=x) between the results of NMR and chemical methods was found. Secondly, we evaluated accuracy and assay range of the NMR method using live mice that were fasted overnight or fed high fat diet (HFD). In fasted mice, a small but quantitative decrease of fat mass (5.1% from 9.1%) was detected. Total decrease of fat and lean mass (5.0 g) in fasted mice was equivalent to the decrease of body weight (5.0 g). In mice fed the HFD, increase of fat mass with relative decrease of lean mass were qualitatively detected in a time-dependent manner. We would like to emphasize that operation of the system was actually easy and measurements were accomplished in a short time (1 minute). Thirdly, we tried to use the NMR system for determination of hepatic fat contents using mice fasted or treated with a PPARgamma agonist; our results showed a quantitative increase in fat by fasting or in decrease in fat by the drug treatment. The changes of fat contents determined by the NMR method were well correlated with the changes in triglyceride and total cholesterol values obtained by the biochemical assays. In conclusion, body composition data

  11. In vivo 31P and multilabel 13C NMR measurements for evaluation of plant metabolic pathways.

    PubMed

    Rijhwani, S K; Ho, C H; Shanks, J V

    1999-01-01

    Reliable measurements of intracellular metabolites are useful for effective plant metabolic engineering. This study explored the application of in situ 31P and 13C NMR spectroscopy for long-term measurements of intracellular pH and concentrations of several metabolites in glycolysis, glucan synthesis, and central carbon metabolic pathways in plant tissues. An NMR perfusion reactor system was designed to allow Catharanthus roseus hairy root cultures to grow for 3-6 weeks, during which time NMR spectroscopy was performed. Constant cytoplasmic pH (7.40+/-0.06), observed during the entire experiment, indicated adequate oxygenation. 13C NMR spectroscopy was performed on hairy root cultures grown in solutions containing 1-13C-, 2-13C-, and 3-13C-labeled glucose in separate experiments and the flow of label was monitored. Activities of pentose phosphate pathways, nonphotosynthetic CO2 fixation, and glucan synthesis pathways were evident from the experimental results. Scrambling of label in glucans also indicated recycling of triose phosphate and their subsequent conversion to hexose phosphates. PMID:10935751

  12. Measuring fast hydrogen exchange rates by NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kateb, Fatiha; Pelupessy, Philippe; Bodenhausen, Geoffrey

    2007-01-01

    We introduce a method to measure hydrogen exchange rates based on the observation of the coherence of a neighboring spin S such as 15N that has a scalar coupling JIS to the exchanging proton I. The decay of Sx coherence under a Carr-Purcell-Meiboom-Gill (CPMG) multiple echo train is recorded in the presence and absence of proton decoupling. This method allows one to extract proton exchange rates up to 10 5 s -1. We could extend the pH range for the study of the indole proton in tryptophan, allowing the determination of the exchange constants of the cationic, zwitterionic, and anionic forms of tryptophan.

  13. Mesodynamics in the SARS nucleocapsid measured by NMR field cycling.

    PubMed

    Clarkson, Michael W; Lei, Ming; Eisenmesser, Elan Z; Labeikovsky, Wladimir; Redfield, Alfred; Kern, Dorothee

    2009-09-01

    Protein motions on all timescales faster than molecular tumbling are encoded in the spectral density. The dissection of complex protein dynamics is typically performed using relaxation rates determined at high and ultra-high field. Here we expand this range of the spectral density to low fields through field cycling using the nucleocapsid protein of the SARS coronavirus as a model system. The field-cycling approach enables site-specific measurements of R (1) at low fields with the sensitivity and resolution of a high-field magnet. These data, together with high-field relaxation and heteronuclear NOE, provide evidence for correlated rigid-body motions of the entire beta-hairpin, and corresponding motions of adjacent loops with a time constant of 0.8 ns (mesodynamics). MD simulations substantiate these findings and provide direct verification of the time scale and collective nature of these motions. PMID:19641854

  14. Electrophoretic deposition of biomaterials

    PubMed Central

    Boccaccini, A. R.; Keim, S.; Ma, R.; Li, Y.; Zhitomirsky, I.

    2010-01-01

    Electrophoretic deposition (EPD) is attracting increasing attention as an effective technique for the processing of biomaterials, specifically bioactive coatings and biomedical nanostructures. The well-known advantages of EPD for the production of a wide range of microstructures and nanostructures as well as unique and complex material combinations are being exploited, starting from well-dispersed suspensions of biomaterials in particulate form (microsized and nanoscale particles, nanotubes, nanoplatelets). EPD of biological entities such as enzymes, bacteria and cells is also being investigated. The review presents a comprehensive summary and discussion of relevant recent work on EPD describing the specific application of the technique in the processing of several biomaterials, focusing on (i) conventional bioactive (inorganic) coatings, e.g. hydroxyapatite or bioactive glass coatings on orthopaedic implants, and (ii) biomedical nanostructures, including biopolymer–ceramic nanocomposites, carbon nanotube coatings, tissue engineering scaffolds, deposition of proteins and other biological entities for sensors and advanced functional coatings. It is the intention to inform the reader on how EPD has become an important tool in advanced biomaterials processing, as a convenient alternative to conventional methods, and to present the potential of the technique to manipulate and control the deposition of a range of nanomaterials of interest in the biomedical and biotechnology fields. PMID:20504802

  15. Measuring chirality in NMR in the presence of a time-dependent electric field

    SciTech Connect

    Walls, Jamie D.; Harris, Robert A.

    2014-06-21

    Traditional nuclear magnetic resonance (NMR) experiments are “blind” to chirality since the spectra for left and right handed enantiomers are identical in an achiral medium. However, theoretical arguments have suggested that the effective Hamiltonian for spin-1/2 nuclei in the presence of electric and magnetic fields can be different for left and right handed enantiomers, thereby enabling NMR to be used to spectroscopically detect chirality even in an achiral medium. However, most proposals to detect the chiral NMR signature require measuring signals that are equivalent to picomolar concentrations for {sup 1}H nuclei, which are outside current NMR detection limits. In this work, we propose to use an AC electric field that is resonantly modulated at the Larmor frequency, thereby enhancing the effect of the chiral term by four to six orders of magnitude. We predict that a steady-state transverse magnetization, whose direction will be opposite for different enantiomers, will build up during application of an AC electric field. We also propose an experimental setup that uses a solenoid coil with an AC current to generate the necessary periodic electric fields that can be used to generate chiral signals which are equivalent to the signal from a {sup 1}H submicromolar concentration.

  16. Surface NMR measurement of proton relaxation times in medium to coarse-grained sand aquifer.

    PubMed

    Shushakov, O A

    1996-01-01

    A surface NMR investigation of groundwater in the geomagnetic field is under study. To detect the surface NMR a wire loop with a diameter of about 100 m, being an antenna for both an exciting field source and the NMR signal receiver, is laid out on the ground. A sinusoidal current pulse with a rectangular envelope is passed through the loop to excite the NMR signal. The carrier frequency of the oscillating current in this pulse is equal to the Larmor frequency of protons in the Earth's magnetic field. The current amplitude is changed up to 200 amps and the pulse duration is fixed and is equal to 40 ms. The exciting pulse is followed by an induction emf signal caused by the Larmor nuclear precession in geomagnetic field. The relaxation times T1, T2, and T2* were measured by the surface NMR for both groundwater in medium to coarse-grained sand at borehole and for bulk water under the ice surface of frozen lake. To determine T1, a longitudinal interference in experiments with repeated pulses was measured. A sequence with equal period between equal excitation pulses was used. The relaxation times T1, T2, measured for bulk water under the ice of the Ob reservoir were 1.0 s and 0.7 s, respectively. To estimate an influence of dissolved oxygen T1 of the same water at the same temperature was measured by lab NMR with and without pumping of oxygen. The relaxation time T1 measured for water in the medium to coarse-grained sand is 0.65 s. The relaxation time T2 estimated by spin echo sequence is found to be equal to 0.15 s. The relaxation time T2* is found to be about 80 ms. This result contradicts published earlier phenomenological correlation between relaxation time T2* and grain size of water-bearing rock. This could be as a result of unsound approach based on grain size or influence of paramagnetic impurities. PMID:8970122

  17. Chromatographic NMR in NMR solvents

    NASA Astrophysics Data System (ADS)

    Carrara, Caroline; Viel, Stéphane; Delaurent, Corinne; Ziarelli, Fabio; Excoffier, Grégory; Caldarelli, Stefano

    2008-10-01

    Recently, it was demonstrated that pseudo-chromatographic NMR experiments could be performed using typical chromatographic solids and solvents. This first setup yielded improved separation of the spectral components of the NMR spectra of mixtures using PFG self-diffusion measurements. The method (dubbed Chromatographic NMR) was successively shown to possess, in favorable cases, superior resolving power on non-functionalized silica, compared to its LC counterpart. To further investigate the applicability of the method, we studied here the feasibility of Chromatographic NMR in common deuterated solvents. Two examples are provided, using deuterated chloroform and water, for homologous compounds soluble in these solvents, namely aromatic molecules and alcohols, respectively.

  18. NMR measurement of oil shale magnetic relaxation at high magnetic field

    USGS Publications Warehouse

    Seymour, Joseph D.; Washburn, Kathryn E.; Kirkland, Catherine M.; Vogt, Sarah J.; Birdwell, Justin E.; Codd, Sarah L.

    2013-01-01

    Nuclear magnetic resonance (NMR) at low field is used extensively to provide porosity and pore-size distributions in reservoir rocks. For unconventional resources, due to low porosity and permeability of the samples, much of the signal exists at very short T2 relaxation times. In addition, the organic content of many shales will also produce signal at short relaxation times. Despite recent improvements in low-field technology, limitations still exist that make it difficult to account for all hydrogen-rich constituents in very tight rocks, such as shales. The short pulses and dead times along with stronger gradients available when using high-field NMR equipment provides a more complete measurement of hydrogen-bearing phases due to the ability to probe shorter T2 relaxation times (-5 sec) than can be examined using low-field equipment. Access to these shorter T2 times allows for confirmation of partially resolved peaks observed in low-field NMR data that have been attributed to solid organic phases in oil shales. High-field (300 MHz or 7 T) NMR measurements of spin-spin T2 and spin-lattice T1 magnetic relaxation of raw and artificially matured oil shales have potential to provide data complementary to low field (2 MHz or 0.05T) measurements. Measurements of high-field T2 and T1-T2 correlations are presented. These data can be interpreted in terms of organic matter phases and mineral-bound water known to be present in the shale samples, as confirmed by Fourier transform infrared spectroscopy, and show distributions of hydrogen-bearing phases present in the shales that are similar to those observed in low field measurements.

  19. Using NMR, SIP, and MS measurements for monitoring subsurface biogeochemical reactions at the Rifle IFRC site

    NASA Astrophysics Data System (ADS)

    Rosier, C. L.; Keating, K.; Williams, K. H.; Robbins, M.; Ntarlagiannis, D.; Grunewald, E.; Walsh, D. O.

    2013-12-01

    The Rifle Integrated Field Research Challenge (IFRC) site is located on a former uranium ore-processing facility in Rifle, Colorado (USA). Although removal of tailings and contaminated surface materials was completed in 1996, residual uranium contamination of groundwater and subsurface sediments remains. Since 2002, research at the site has primarily focused on quantifying uranium mobility associated with stimulated and natural biogeochemical processes. Uranium mobility at the Rifle IFRC site is typically quantified through direct sampling of groundwater; however, direct sampling does not provide information about the solid phase material outside of the borehole and continuous measurements are not always possible due to multiple constraints. Geophysical methods have been suggested as a minimally invasive alternative approach for long term monitoring of biogeochemical reactions associated with uranium remediation. In this study, nuclear magnetic resonance (NMR), spectral induced polarization (SIP), and magnetic susceptibility (MS) are considered as potential geophysical methods for monitoring the biogeochemical reactions occurring at the Rifle IFRC site. Additionally, a pilot field study using an NMR borehole-logging tool was carried out at the Rifle IFRC site. These methods are sensitive to changes in the chemical and physical subsurface properties that occur as a result of bioremediation efforts; specifically, changes in the redox state and chemical form of iron, production of iron sulfide minerals, production of the magnetic mineral magnetite, and associated changes in the pore geometry. Laboratory experiments consisted of monitoring changes in the NMR, SIP and MS response of an acetate-amended columns packed with sediments from the Rifle IFRC site over the course of two months. The MS values remained relatively stable throughout the course of the experiment suggesting negligible production of magnetic phases (e.g. magnetite, pyrrhotite) as a result of enhanced

  20. {sup 19}F NMR measurements of NO production in hypertensive ISIAH and OXYS rats

    SciTech Connect

    Bobko, Andrey A. . E-mail: bobko@kinetics.nsc.ru; Sergeeva, Svetlana V.; Bagryanskaya, Elena G.; Markel, Arkadii L.; Khramtsov, Valery V.; Reznikov, Vladimir A.; Kolosova, Nataljya G.

    2005-05-06

    Recently we demonstrated the principal possibility of application of {sup 19}F NMR spin-trapping technique for in vivo {sup {center_dot}}NO detection [Free Radic. Biol. Med. 36 (2004) 248]. In the present study, we employed this method to elucidate the significance of {sup {center_dot}}NO availability in animal models of hypertension. In vivo {sup {center_dot}}NO-induced conversion of the hydroxylamine of the fluorinated nitronyl nitroxide (HNN) to the hydroxylamine of the iminonitroxide (HIN) in hypertensive ISIAH and OXYS rat strains and normotensive Wistar rat strain was measured. Significantly lower HIN/HNN ratios were measured in the blood of the hypertensive rats. The NMR data were found to positively correlate with the levels of nitrite/nitrate evaluated by Griess method and negatively correlate with the blood pressure. In comparison with other traditionally used methods {sup 19}F NMR spectroscopy allows in vivo evaluation of {sup {center_dot}}NO production and provides the basis for in vivo {sup {center_dot}}NO imaging.

  1. Precision and sensitivity optimization of quantitative measurements in solid state NMR

    NASA Astrophysics Data System (ADS)

    Ziarelli, Fabio; Viel, Stéphane; Sanchez, Stéphanie; Cross, David; Caldarelli, Stefano

    2007-10-01

    This work presents a methodology for optimizing the precision, accuracy and sensitivity of quantitative solid state NMR measurements based on the external reference method. It is shown that the sample must be exclusively located within and completely span the coil region where the NMR response is directly proportional to the sample amount. We describe two methods to determine this "quantitative" coil volume, based on whether the probe is equipped or not with a gradient coil. In addition, to improve the sensitivity and the accuracy, an optimum rotor packing design is described, which allows the sample volume of the rotor to be matched to the quantitative coil volume. Experiments conducted on adamantane and NaCl, which are representative of a soft and hard material, respectively, show that one order of magnitude increase in experimental precision can be achieved with this methodology. Interestingly, the precision can be further improved by using the ERETIC™ method in order to compensate for most instrumental instabilities.

  2. Alternative approach to the standardization of NMR spectra. Direct measurement of nuclear magnetic shielding in molecules.

    PubMed

    Jackowski, Karol; Jaszuński, Michał; Wilczek, Marcin

    2010-02-25

    Exploring the relation between shielding constants, resonance frequencies and magnetic moments of the nuclei we demonstrate that nuclear magnetic shielding can be directly observed from NMR spectra. In this approach, the absolute shielding constants of all the nuclei can be related to a single reference scale, with atomic (3)He as the primary standard. The accuracy of the data obtained using our method is confirmed comparing the (1)H and (13)C shielding constants for a series of deuterated compounds with those determined analyzing the traditional chemical shifts. Since the use of helium-3 is not in general a practical alternative, we next transfer the reference standard to the (2)H signals of external lock solvents, in this way making the method easy and ready for application with most NMR spectrometers. Finally, we illustrate our new method with the measurements of the (2/1)H primary isotope effects in several liquid deuterated solvents. PMID:20112974

  3. A unified mathematical theory of electrophoretic processes

    NASA Technical Reports Server (NTRS)

    Bier, M.; Palusinski, O. A.; Mosher, R. A.; Graham, A.; Saville, D. A.

    1983-01-01

    A mathematical theory is presented which shows that each of the four classical electrophoretic modes (zone electrophoresis, moving boundary electrophoresis, isotachophoresis, and isoelectric focusing) is based on the same general principles and can collectively be described in terms of a single set of equations. This model can predict the evolution of the four electrophoretic modes as a function of time. The model system is one-dimensional, neglecting the effects of electroosmosis, temperature gradients, and any bulk flows of liquid. The model is based on equations which express the components' dissociation equilibria, the mass transport due to electromigration and diffusion, electroneutrality, and the conservation of mass and charge. The model consists of a system of coupled partial differential and nonlinear algebraic equations which can be solved numerically by use of a computer. The versatility of this model was verified using an example of a three-component system containing cacodylate, tris hydroxylmethylaminomethane, and histidine. Results show that this model not only correctly predicts the characteristic features of each electrophoretic mode, but also gives details of the concentration, pH, and conductivity profiles not easily amenable to direct experimental measurement.

  4. A portable single-sided magnet system for remote NMR measurements of pulmonary function.

    PubMed

    Dabaghyan, Mikayel; Muradyan, Iga; Hrovat, Alan; Butler, James; Frederick, Eric; Zhou, Feng; Kyriazis, Angelos; Hardin, Charles; Patz, Samuel; Hrovat, Mirko

    2014-12-01

    In this work, we report initial results from a light-weight, low field magnetic resonance device designed to make relative pulmonary density measurements at the bedside. The development of this device necessarily involves special considerations for the magnet, RF and data acquisition schemes as well as a careful analysis of what is needed to provide useful information in the ICU. A homogeneous field region is created remotely from the surface of the magnet such that when the magnet is placed against the chest, an NMR signal is measured from a small volume in the lung. In order to achieve portability, one must trade off field strength and therefore spatial resolution. We report initial measurements from a ping-pong ball size region in the lung as a function of lung volume. As expected, we measured decreased signal at larger lung volumes since lung density decreases with increasing lung volume. Using a CPMG sequence with ΔTE=3.5 ms and a 20 echo train, a signal to noise ratio ~1100 was obtained from an 8.8mT planar magnet after signal averaging for 43 s. This is the first demonstration of NMR measurements made on a human lung with a light-weight planar NMR device. We argue that very low spatial resolution measurements of different lobar lung regions will provide useful diagnostic information for clinicians treating Acute Respiratory Distress Syndrome as clinicians want to avoid ventilator pressures that cause either lung over distension (too much pressure) or lung collapse (too little pressure). PMID:24953556

  5. A portable single-sided magnet system for remote NMR measurements of pulmonary function

    PubMed Central

    Mikayel, Dabaghyan; Iga, Muradyan; James, Butler; Eric, Frederick; Feng, Zhou; Angelos, Kyriazis; Charles, Hardin; Samuel, Patz; Mirko, Hrovat

    2014-01-01

    In this work, we report initial results from a light-weight, low field magnetic resonance device designed to make relative pulmonary density measurements at the bedside. The development of this device necessarily involves special considerations for the magnet, RF and data acquisition schemes as well as a careful analysis of what is needed to provide useful information in the ICU. A homogeneous field region is created remotely from the surface of the magnet such that when the magnet is placed against the chest, an NMR signal is measured from a small volume in the lung. In order to achieve portability, one must trade off field strength and therefore spatial resolution. We report initial measurements from a ping-pong ball size region in the lung as a function of lung volume. As expected, we measured decreased signal at larger lung volumes since lung density decreases with increasing lung volume. Using a CPMG sequence with ΔTE=3.5 ms and a 20 echo train, a signal to noise ratio ~1100 was obtained from an 8.8mT planar magnet after signal averaging for 43 s. This is the first demonstration of NMR measurements made on a human lung with a light-weight planar NMR device. We argue that very low spatial resolution measurements of different lobar lung regions will provide useful diagnostic information for clinicians treating Acute Respiratory Distress Syndrome as clinicians want to avoid ventilator pressures that cause either lung over distension (too much pressure) or lung collapse (too little pressure). PMID:24953556

  6. Fractional order analysis of Sephadex gel structures: NMR measurements reflecting anomalous diffusion

    NASA Astrophysics Data System (ADS)

    Magin, Richard L.; Akpa, Belinda S.; Neuberger, Thomas; Webb, Andrew G.

    2011-12-01

    We report the appearance of anomalous water diffusion in hydrophilic Sephadex gels observed using pulse field gradient (PFG) nuclear magnetic resonance (NMR). The NMR diffusion data was collected using a Varian 14.1 Tesla imaging system with a home-built RF saddle coil. A fractional order analysis of the data was used to characterize heterogeneity in the gels for the dynamics of water diffusion in this restricted environment. Several recent studies of anomalous diffusion have used the stretched exponential function to model the decay of the NMR signal, i.e., exp[-( bD) α], where D is the apparent diffusion constant, b is determined the experimental conditions (gradient pulse separation, durations and strength), and α is a measure of structural complexity. In this work, we consider a different case where the spatial Laplacian in the Bloch-Torrey equation is generalized to a fractional order model of diffusivity via a complexity parameter, β, a space constant, μ, and a diffusion coefficient, D. This treatment reverts to the classical result for the integer order case. The fractional order decay model was fit to the diffusion-weighted signal attenuation for a range of b-values (0 < b < 4000 s mm -2). Throughout this range of b values, the parameters β, μ and D, were found to correlate with the porosity and tortuosity of the gel structure.

  7. Detection of the water level in fractured phreatic aquifers using nuclear magnetic resonance (NMR) geophysical measurements

    NASA Astrophysics Data System (ADS)

    Gev, Israel; Goldman, Mark; Rabinovich, Boris; Rabinovich, Michael; Issar, Arie

    1996-06-01

    Correlation of geophysical data collected using the NMR method in the Negev Desert, Israel, with hydrogeological data from nearby observation wells is presented. The experiment was conducted near Kibbutz Revivim in the Besor drainage system (Fig. 1). The objective of the survey was to detect groundwater layers in the Quaternary cover filling and Eocene fractured aquifers down to a depth of 100 m. The experiment was performed using a combination of two different geophysical techniques, namely the NMR and time domain electromagnetic (TDEM) methods. The geophysical results were verified by measuring the water level in three observation wells, two of which were drilled several months after the geophysical survey was carried out. The water level measured in these follow-up observation wells shortly after drilling did not coincide with the geophysical data. However, it settled over a period of time and finally stabilized at a depth very similar to that obtained from the NMR measurements. This phenomenon is caused by the fractured nature of the phreatic aquifer. Since the flow of water in such aquifers is confined by the fractures, the appearance of water in the well during or shortly after drilling is determined solely by the intersection of the well and the fracture. Our experiments showed that geophysical measurements in fractured phreatic aquifers may have a distinct advantage over direct borehole measurements, since the former average the depth to the water table over large areas (several thousand square meters) while the latter are limited by the area of the borehole cross-section (several tens of square centimeters).

  8. Using NMR decay-time measurements to monitor and characterize DNAPL and moisture in subsurface porous media

    SciTech Connect

    Timothy A. White; Russel C. Hertzog; Christian Straley

    2007-12-01

    Knowing how environmental properties affect dense nonaqueous phase liquid (DNAPL) solvent flow in the subsurface is essential for developing models of flow and transport in the vadose zone necessary for designing remediation and long-term stewardship strategies. For example, one must know if solvents are flowing in water-wetted or solvent-wetted environments, the pore-size distribution of the region containing DNAPLs, and the impact of contaminated plumes and their transport mechanisms in porous media. Our research investigates the capability and limitations of low-field proton nuclear magnetic resonance (NMR) relaxation decay-rate measurements for determining environmental properties affecting DNAPL solvent flow in the subsurface. The measurements that can be performed with the laboratory low-field system can also be performed in situ in the field with the current generation of commercial borehole logging tools. The oil and gas industry uses NMR measurements in deep subsurface, consolidated formations to determine porosity and hydrocarbon content and to estimate formation permeability. These determinations rely on the ability of NMR to distinguish between water and hydrocarbons in the pore space and to obtain the distribution of pore sizes from relaxation decay-rate distributions. In this paper we will show how NMR measurement techniques can be used to characterize, monitor, and evaluate the dynamics of mixed-fluids (water-DNAPL) in unconsolidated near-surface porous environments and describe the use of proton NMR T2 (spin-spin relaxation time) measurements in unconsolidated sandy-soil samples to identify and characterize the presence of DNAPLs in these environments. The potential of NMR decay-rate distributions for characterizing DNAPL fluids in the subsurface and understanding their flow mechanisms has not previously been exploited; however, near-surface unsaturated vadose zone environments do provide unique challenges for using NMR measurements. These

  9. Electrophoretic Deposition for Fabricating Microbatteries

    NASA Technical Reports Server (NTRS)

    West, William; Whitacre, Jay; Bugga, Ratnakumar

    2003-01-01

    An improved method of fabrication of cathodes of microbatteries is based on electrophoretic deposition. Heretofore, sputtering (for deposition) and the use of photoresist and liftoff (for patterning) have been the primary methods of fabricating components of microbatteries. The volume of active electrode material that can be deposited by sputtering is limited, and the discharge capacities of prior microbatteries have been limited accordingly. In addition, sputter deposition is slow. In contrast, electrophoretic deposition is much faster and has shown promise for increasing discharge capacities by a factor of 10, relative to those of microbatteries fabricated by prior methods.

  10. Measurement and Quantification of Heterogeneity, Flow, and Mass Transfer in Porous Media Using NMR Low-Field Techiques

    NASA Astrophysics Data System (ADS)

    Paciok, E.; Olaru, A. M.; Haber, A.; van Landeghem, M.; Haber-Pohlmeier, S.; Sucre, O. E.; Perlo, J.; Casanova, F.; Blümich, B.; RWTH Aachen Mobile Low-Field NMR

    2011-12-01

    Nuclear magnetic resonance (NMR) is renowned for its unique potential to both reveal and correlate spectroscopic, relaxometric, spatial and dynamic properties in a large variety of organic and inorganic systems. NMR has no restrictions regarding sample opacity and is an entirely non-invasive method, which makes it the ideal tool for the investigation of porous media. However, for years NMR research of soils was limited by the use of high-field NMR devices, which necessitated elaborate NMR experiments and were not applicable to bulky samples or on-site field measurements. The evolution of low-field NMR devices during the past 20 years has brought forth portable, small-scale NMR systems with open and closed magnet arrangements specialized to specific NMR applications. In combination with recent advances in 2D-NMR Laplace methodology [1], low-field NMR has opened up the possibility to study real-life microporous systems ranging from granular media to natural soils and oil well boreholes. Thus, information becomes available, which before has not been accessible with high-field NMR. In this work, we present our recent progress in mobile low-field NMR probe design for field measurements of natural soils: a slim-line logging tool, which can be rammed into the soil of interest on-site. The performance of the device is demonstrated in measurements of moisture profiles of model soils [2] and field measurements of relaxometric properties and moisture profiles of natural soils [3]. Moreover, an improved concept of the slim-line logging tool is shown, with a higher excitation volume and a better signal-to-noise due to an improved coil design. Furthermore, we present our recent results in 2D exchange relaxometry and simulation. These include relaxation-relaxation experiments on natural soils with varying degree of moisture saturation, where we could draw a connection between the relaxometric properties of the soil to its pore size-related diffusivity and to its clay content

  11. Measurement of nuclear magnetic dipole—dipole couplings in magic angle spinning NMR

    NASA Astrophysics Data System (ADS)

    Tycko, Robert; Dabbagh, Gary

    1990-10-01

    We describe a method for measuring nuclear magnetic dipole—dipole couplings in NMR spectra of solids undergoing rapid magic angle spinning (MAS). We show in theory, simulations, and experiments that the couplings, which are averaged out by MAS alone, can be recovered by applying simple resonant radiofrequency pulse sequences in synchrony with the sample rotation. Experimental 13C dipolar powder pattern spectra of polycrystalline ( 13CH 3) 2C(OH)SO 3Na obtained in a two-dimensional experiment based on this method are presented. The method provides a means of determining internuclear distances in polycrystalline and noncrystalline solids while retaining the high resolution and sensitivity afforded by MAS.

  12. Electrophoretic Process For Purifying Wastewater

    NASA Technical Reports Server (NTRS)

    Sammons, David W.; Twitty, Garland E.; Sharnez, Rizwan; Egen, Ned B.

    1992-01-01

    Microbes, poisonous substances, and colloidal particles removed by combination of electric fields. Electrophoretic process removes pathogenicorganisms, toxins, toxic metals, and cooloidal soil particles from wastewater. Used to render domestic, industrial, and agricultural wastewater streams potable. Process also useful in bioregenerative and other closed systems like in space stations and submarines, where water must be recycled.

  13. Optimized slim-line logging NMR tool to measure soil moisture in situ.

    PubMed

    Perlo, Josefina; Danieli, Ernesto; Perlo, Juan; Blümich, Bernhard; Casanova, Federico

    2013-08-01

    We report the optimization of a slim-line logging NMR tool carried out by maximizing the signal-to-noise ratio of the NMR measurements. The tool, based on cylindrical permanent magnets of 20 cm length and 5 cm diameter, has a penetration depth of about 2 cm measured from its surface. This is obtained thanks to a large radio frequency coil whose dimensions are comparable to the sensor size. An analytical expression of the SNR as a function of parameters which take into account the interaction between the radio frequency coil and the magnet shielding is developed. In view of the external constrains such as the one imposed by the excavation hole, a proper tool size is determined in the optimization process. Due to its size and properties, the sensor is suitable to measure water content in the vadose zone, which is the zone comprised within the first meters of the Earth surface and whose study is important for improving water management in agriculture and for refining climate models. PMID:23757362

  14. Probing the permeability of porous media by NMR measurement of stochastic dispersion dynamics

    NASA Astrophysics Data System (ADS)

    Brosten, Tyler; Maier, Robert; Codd, Sarah; Vogt, Sarah; Seymour, Joseph

    2011-11-01

    A generalized short-time expansion of hydrodynamic dispersion is derived using non-linear response theory. The result is in accordance with the well-known reduced cases of shear flow in ducts and pipes. In terms of viscous dominated (low Reynolds number) flow in porous media the generalized expansion facilitates the measurement of permeability by PGSE-NMR measurement of time dependent molecular displacement dynamics. To be more precise, for porous media characterized by a homogeneous permeability coefficient along the direction of flow K, and fluid volume fraction ɛ, the effective dispersion coefficient D (t) = < | R- |2 > /6 t of molecular displacements R due to flow and diffusion for a saturating fluid of molecular diffusivity κ in viscous dominated flow is shown to be partially governed by the coefficient of permeability at short times. The short-time expansion is shown to be in agreement with pulsed field gradient spin echo NMR measurement of D (t) in a random sphere pack media and analogous pore-scale random-walk particle tracking transport simulation.

  15. Optimized slim-line logging NMR tool to measure soil moisture in situ

    NASA Astrophysics Data System (ADS)

    Perlo, Josefina; Danieli, Ernesto; Perlo, Juan; Blümich, Bernhard; Casanova, Federico

    2013-08-01

    We report the optimization of a slim-line logging NMR tool carried out by maximizing the signal-to-noise ratio of the NMR measurements. The tool, based on cylindrical permanent magnets of 20 cm length and 5 cm diameter, has a penetration depth of about 2 cm measured from its surface. This is obtained thanks to a large radio frequency coil whose dimensions are comparable to the sensor size. An analytical expression of the SNR as a function of parameters which take into account the interaction between the radio frequency coil and the magnet shielding is developed. In view of the external constrains such as the one imposed by the excavation hole, a proper tool size is determined in the optimization process. Due to its size and properties, the sensor is suitable to measure water content in the vadose zone, which is the zone comprised within the first meters of the Earth surface and whose study is important for improving water management in agriculture and for refining climate models.

  16. Composite alignment media for the measurement of independent sets of NMR residual dipolar couplings.

    PubMed

    Ruan, Ke; Tolman, Joel R

    2005-11-01

    The measurement of independent sets of NMR residual dipolar couplings (RDCs) in multiple alignment media can provide a detailed view of biomolecular structure and dynamics, yet remains experimentally challenging. It is demonstrated here that independent sets of RDCs can be measured for ubiquitin using just a single alignment medium composed of aligned bacteriophage Pf1 particles embedded in a strained polyacrylamide gel matrix. Using this composite medium, molecular alignment can be modulated by varying the angle between the directors of ordering for the Pf1 and strained gel matrix, or by varying the ionic strength or concentration of the Pf1 particles. This approach offers significant advantages in that greater experimental control can be exercised over the acquisition of multi-alignment RDC data while a homogeneous chemical environment is maintained across all of the measured RDC data. PMID:16248635

  17. Estimating Pore Properties from NMR Relaxation Time Measurements in Heterogeneous Media

    NASA Astrophysics Data System (ADS)

    Grunewald, E.; Knight, R.

    2008-12-01

    The link between pore geometry and the nuclear magnetic resonance (NMR) relaxation time T2 is well- established for simple systems but is poorly understood for complex media with heterogeneous pores. Conventional interpretation of NMR relaxation data employs a model of isolated pores in which each hydrogen proton samples only one pore type, and the T2-distribution is directly scaled to estimate a pore-size distribution. During an actual NMR measurement, however, each proton diffuses through a finite volume of the pore network, and so may sample multiple pore types encountered within this diffusion cell. For cases in which heterogeneous pores are strongly coupled by diffusion, the meaning of the T2- distribution is not well understood and further research is required to determine how such measurements should be interpreted. In this study we directly investigate the implications of pore coupling in two groups of laboratory NMR experiments. We conduct two suites of experiments, in which samples are synthesized to exhibit a range of pore coupling strengths using two independent approaches: (a) varying the scale of the diffusion cell and (b) varying the scale over which heterogeneous pores are encountered. In the first set of experiments, we vary the scale of the diffusion cell in silica gels which have a bimodal pore-size distribution comprised of intragrannular micropores and much larger intergrannular pores. The untreated gel exhibits strong pore coupling with a single broad peak observed in the T2-distribution. By treating the gel with varied amounts of paramagnetic iron surface coatings, we decrease the surface relaxation time, T2S, and effectively decrease both the size of the diffusion cell and the degree of pore coupling. As more iron is coated to the grain surfaces, we observe a separation of the broad T2-distribution into two peaks that more accurately represent the true bimodal pore-size distribution. In the second set of experiments, we vary the scale over

  18. Pulsed field gradient magic angle spinning NMR self-diffusion measurements in liquids.

    PubMed

    Viel, Stéphane; Ziarelli, Fabio; Pagès, Guilhem; Carrara, Caroline; Caldarelli, Stefano

    2008-01-01

    Several investigations have recently reported the combined use of pulsed field gradient (PFG) with magic angle spinning (MAS) for the analysis of molecular mobility in heterogeneous materials. In contrast, little attention has been devoted so far to delimiting the role of the extra force field induced by sample rotation on the significance and reliability of self-diffusivity measurements. The main purpose of this work is to examine this phenomenon by focusing on pure liquids for which its impact is expected to be largest. Specifically, we show that self-diffusion coefficients can be accurately determined by PFG MAS NMR diffusion measurements in liquids, provided that specific experimental conditions are met. First, the methodology to estimate the gradient uniformity and to properly calibrate its absolute strength is briefly reviewed and applied on a MAS probe equipped with a gradient coil aligned along the rotor spinning axis, the so-called 'magic angle gradient' coil. Second, the influence of MAS on the outcome of PFG MAS diffusion measurements in liquids is investigated for two distinct typical rotors of different active volumes, 12 and 50 microL. While the latter rotor led to totally unreliable results, especially for low viscosity compounds, the former allowed for the determination of accurate self-diffusion coefficients both for fast and slowly diffusing species. Potential implications of this work are the possibility to measure accurate self-diffusion coefficients of sample-limited mixtures or to avoid radiation damping interferences in NMR diffusion measurements. Overall, the outlined methodology should be of interest to anyone who strives to improve the reliability of MAS diffusion studies, both in homogeneous and heterogeneous media. PMID:18006344

  19. 19F NMR measurements of the rotational mobility of proteins in vivo.

    PubMed Central

    Williams, S P; Haggie, P M; Brindle, K M

    1997-01-01

    Three glycolytic enzymes, hexokinase, phosphoglycerate kinase, and pyruvate kinase, were fluorine labeled in the yeast Saccharomyces cerevisiae by biosynthetic incorporation of 5-fluorotryptophan. 19F NMR longitudinal relaxation time measurements on the labeled enzymes were used to assess their rotational mobility in the intact cell. Comparison with the results obtained from relaxation time measurements of the purified enzymes in vitro and from theoretical calculations showed that two of the labeled enzymes, phosphoglycerate kinase and hexokinase, were tumbling in a cytoplasm that had a viscosity approximately twice that of water. There were no detectable signals from pyruvate kinase in vivo, although it could be detected in diluted cell extracts, indicating that there was some degree of motional restriction of the enzyme in the intact cell. PMID:8994636

  20. Observation of separate cation and anion electrophoretic mobilities in pure ionic liquids

    NASA Astrophysics Data System (ADS)

    Zhang, Zhiyang; Madsen, Louis A.

    2014-02-01

    Ionic liquids (ILs) continue to show relevance in many fields, from battery electrolytes, to carbon capture, to advanced separations. These highly ion-dense fluids present unique challenges in understanding their electrochemical properties due to deviations in behavior from existing electrolyte theories. Here we present a novel characterization of ILs using electrophoretic NMR (ENMR) to determine separate cation and anion mobilities. This method uses an applied electric field coincident with a pulsed magnetic field gradient to encode the E-field driven flow into NMR signals for cations (1H) and anions (19F). We describe the detailed design of these experiments, including quantitative analysis of artifact mitigation and necessary control experiments. We then explore mobilities and diffusion coefficients for two representative ILs: 1-ethyl-3-methyl imidazolium tetrafluoroborate ([C2mim][BF4]) and 1-ethyl-3-methyl imidazolium trifluoromethanesulfonate ([C2mim][TfO]). We further use the individual ion mobilities to calculate the bulk net conductivity, which closely agrees with bulk conductivity measurements obtained using impedance spectroscopy. These observations represent the first reliable measurements of cation and anion mobilities in pure ILs, with errors of ±7%. We discuss this advanced experimental methodology in detail, as well as implications of these sensitive measurements for understanding conduction mechanisms in ion-dense electrolytes.

  1. Observation of separate cation and anion electrophoretic mobilities in pure ionic liquids.

    PubMed

    Zhang, Zhiyang; Madsen, Louis A

    2014-02-28

    Ionic liquids (ILs) continue to show relevance in many fields, from battery electrolytes, to carbon capture, to advanced separations. These highly ion-dense fluids present unique challenges in understanding their electrochemical properties due to deviations in behavior from existing electrolyte theories. Here we present a novel characterization of ILs using electrophoretic NMR (ENMR) to determine separate cation and anion mobilities. This method uses an applied electric field coincident with a pulsed magnetic field gradient to encode the E-field driven flow into NMR signals for cations ((1)H) and anions ((19)F). We describe the detailed design of these experiments, including quantitative analysis of artifact mitigation and necessary control experiments. We then explore mobilities and diffusion coefficients for two representative ILs: 1-ethyl-3-methyl imidazolium tetrafluoroborate ([C2mim][BF4]) and 1-ethyl-3-methyl imidazolium trifluoromethanesulfonate ([C2mim][TfO]). We further use the individual ion mobilities to calculate the bulk net conductivity, which closely agrees with bulk conductivity measurements obtained using impedance spectroscopy. These observations represent the first reliable measurements of cation and anion mobilities in pure ILs, with errors of ±7%. We discuss this advanced experimental methodology in detail, as well as implications of these sensitive measurements for understanding conduction mechanisms in ion-dense electrolytes. PMID:24588161

  2. Application of (19)  F time-domain NMR to measure content in fluorine-containing drug products.

    PubMed

    Silva Elipe, Maria Victoria; Li, Lan; Nagapudi, Karthik; Kook, Alan M; Cobas, Carlos; Iglesias, Isaac; Peng, Chen

    2016-06-01

    It is necessary to show that the active content in the dosage form of drugs is within a certain narrow range of the label claim. In case of fluorinated drugs, the active content can be measured by high field solid state NMR because the excipients lack fluorine. To make NMR reachable to any laboratory, simple to use, and at a low cost, measurement of (19)  F nucleus using a 23 MHz (for (1) H) low field benchtop time-domain (TD) NMR was investigated. Three fluorinated drug products, cinacalcet, lansoprazole, and ciprofloxacin, were chosen for this study. The doses for these drug products range from 15 to 500 mg. The average drug content measured using (19)  F TD-NMR compares well with the reported label claims for the three drugs tested. (19)  F TD-NMR is a simple and non-destructive technique to measure drug content in tablets. In addition, the accessibility and simplicity of the technique makes it an excellent process analytical technology tool for development and manufacturing in the pharmaceutical industry. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25773191

  3. Design Modification of Electrophoretic Equipment

    NASA Technical Reports Server (NTRS)

    Reddick, J. M.; Hirsch, I.

    1973-01-01

    The improved design of a zone electrophoretic sampler is reported that can be used in mass screening for hemoglobin S, the cause of sickle cell anemia. Considered is a high voltage multicell cellulose acetate device that requires 5 to 6 minutes electrophoresis periods; cells may be activitated individually or simultaneously. A multisample hemoglobin applicator standardizes the amount of sample applied and transfers the homolysate to the electrical wires.

  4. Intracellular free calcium concentration measured with /sup 19/F NMR spectroscopy in intact ferret hearts

    SciTech Connect

    Marban, E.; Kitakaze, M.; Kusuoka, H.; Porterfield, J.K.; Yue, D.T.; Chacko, V.P.

    1987-08-01

    Changes in the intracellular free Ca/sup 2 +/ concentration, (Ca/sup 2 +/)/sub i/, mediate excitation-contraction coupling in the heart and contribute to cellular injury during ischemia and reperfusion. To study these processes directly, the authors measured (Ca/sup 2 +/)/sub i/ in perfused ferret (Mustela putorius furo) hearts using /sup 19/F NMR spectroscopy to detect the 5,5'-difluoro derivative of the Ca/sup 2 +/ chelator, 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). To load cells, hearts were perfused with the acetoxymethyl ester derivative of 5,5'-F/sub 2/-BAPTA. They measured /sup 19/F NMR spectra and left ventricular pressure simultaneously,at rest and during pacing at various external Ca concentrations ((Ca)/sub 0/). Although contractile force was attenuated by the Ca/sup 2 +/ buffering properties of 5,5'-F/sup 2/-BAPTA, the decrease in pressure could be overcome by raising (Ca)/sub 0/. The mean value of 104 nM for (Ca/sup 2 +/)/sub i/ at rest in the perfused heart agrees well with previous measurements in isolated ventricular muscle. During pacing at 0.6-4 Hz, time-averaged (Ca/sup 2 +/)/sub i/ increased; the effect of pacing was augmented by increasing (Ca)/sub 0/. (Ca/sup 2 +/)/sub i/ more than tripled during 10-20 min of global ischemia, and returned toward control levels upon reperfusion. This approach promises to be particularly useful in investigating the physiology of intact hearts and the pathophysiology of alterations in the coronary circulation

  5. O-tert-Butyltyrosine, an NMR tag for high-molecular-weight systems and measurements of submicromolar ligand binding affinities.

    PubMed

    Chen, Wan-Na; Kuppan, Kekini Vahini; Lee, Michael David; Jaudzems, Kristaps; Huber, Thomas; Otting, Gottfried

    2015-04-01

    O-tert-Butyltyrosine (Tby) is an unnatural amino acid that can be site-specifically incorporated into proteins using established orthogonal aminoacyl-tRNA synthetase/tRNA systems. Here we show that the tert-butyl group presents an outstanding NMR tag that can readily be observed in one-dimensional (1)H NMR spectra without any isotope labeling. Owing to rapid bond rotations and the chemical equivalence of the protons of a solvent-exposed tert-butyl group from Tby, the singlet resonance from the tert-butyl group generates an easily detectable narrow signal in a spectral region with limited overlap with other methyl resonances. The potential of the tert-butyl (1)H NMR signal in protein research is illustrated by the observation and assignment of two resonances in the Bacillus stearothermophilus DnaB hexamer (320 kDa), demonstrating that this protein preferentially assumes a 3-fold rather than 6-fold symmetry in solution, and by the quantitative measurement of the submicromolar dissociation constant Kd (0.2 μM) of the complex between glutamate and the Escherichia coli aspartate/glutamate binding protein (DEBP, 32 kDa). The outstanding signal height of the (1)H NMR signal of the Tby tert-butyl group allows Kd measurements using less concentrated protein solutions than usual, providing access to Kd values 1 order of magnitude lower than established NMR methods that employ direct protein detection for Kd measurements. PMID:25789794

  6. Borehole measurement of NMR characteristics of earth formations, and interpretations thereof

    SciTech Connect

    Kleinberg, R.L.; Griffin, D.D.; Fukuhara, M.; Sezginer, A.; Chew, W.C.; Kenyon, W.E.; Day, P.I.; Lipsicas, M.

    1990-06-12

    This patent describes a method of determining a characteristic of an earth formation traversed by a borehole. It comprises: measuring nuclear magnetic resonance decay signals representative of transverse (T{sub 2}) or observed (T{sub 2}*) magnetic relaxation of a population of particles in the formation following different magnetic polarization periods; selecting a set of values of the signals; comparing the set of values directly to a representation of NMR decay which includes amplitude A and longitudinal relaxation time T{sub 1} terms and simultaneously depends on both the decay time t{sub {ital dec}} and polarization periods t{sub {ital pol}} associated with the values; generating values of amplitude and T{sub 1} parameters which optimize the fit between the compared set of values and the representation; determining the formation characteristic in response to the generated values of at least one of the terms---amplitude or T{sub 1}.

  7. Dynamical theory of spin noise and relaxation: Prospects for real-time NMR measurements.

    PubMed

    Field, Timothy R

    2014-11-01

    Recent developments in theoretical aspects of spin noise and relaxation and their interrelationship reveal a modified spin density, distinct from the density matrix, as the necessary object to describe fluctuations in spin systems. These fluctuations are to be viewed as an intrinsic quantum mechanical property of such systems immersed in random magnetic environments and are observed as "spin noise" in the absence of any radio frequency excitation. With the prospect of ultrafast digitization, the role of spin noise in real-time parameter extraction for (NMR) spin systems, and the advantage over standard techniques, is of essential importance, especially for systems containing a small number of spins. In this article we outline prospects for harnessing the recent dynamical theory in terms of spin-noise measurement, with attention to real-time properties. PMID:25493776

  8. NMR measurement of the spin magnetization and spin dynamics in the quantum Hall regimes

    NASA Astrophysics Data System (ADS)

    Barrett, S. E.; Dabbagh, G.; Pfeiffer, L. N.; West, K. W.; Tycko, R.

    1996-07-01

    We review our recent measurements of the Knight shift ( Ks( v, T)) and spin-lattice relaxation time ( T1( v,T) of the 71Ga nuclei located in n-doped GaAs quantum wells using optically pumped NMR, for Landau-level filling 0.66 < v < 1.76 and temperature 1.55K< T )drops precipitously on either side of v = 1, which is evidence that the charged excitations of the v = 1 ground state are finite-size skyrmions. For v < 1, the data are consistent with a many-body ground state which is not fully spin-polarized, with a very small spin-excitation gap that increases as v → 2/3.

  9. Velocity autocorrelation spectra in molten polymers measured by NMR modulated gradient spin-echo

    NASA Astrophysics Data System (ADS)

    Stepišnik, Janez; Mohorič, Aleš; Mattea, Carlos; Stapf, Siegfried; Serša, Igor

    2014-04-01

    The segmental dynamics in molten linear polymers is studied by the NMR method of modulated gradient spin-echo, which directly probes a spectrum of molecular velocity autocorrelation function. Diffusion spectra of mono-disperse poly(isoprene-1.4) with different molecular masses, measured in the frequency range 0.1-10 kHz at a temperature of 26\\ ^{\\circ}\\text{C} , have a form similar to the spectrum of Rouse chain dynamics, which implicates the tube-Rouse motion as the dominant dynamic process in this frequency range. The scaling of the center-of-mass diffusion coefficient, given from the fitting parameters, changes from N^{-1} into N^{-2.4} at around N \\approx 3\\text{-}5 Kuhn steps, which is less than predicted by theory and simulations, while the correlation times of the tube-Rouse mode do not follow the anticipated scaling.

  10. Lithium ion diffusion in Li β-alumina single crystals measured by pulsed field gradient NMR spectroscopy

    SciTech Connect

    Chowdhury, Mohammed Tareque Takekawa, Reiji; Iwai, Yoshiki; Kuwata, Naoaki; Kawamura, Junichi

    2014-03-28

    The lithium ion diffusion coefficient of a 93% Li β-alumina single crystal was measured for the first time using pulsed field gradient (PFG) NMR spectroscopy with two different crystal orientations. The diffusion coefficient was found to be 1.2 × 10{sup −11} m{sup 2}/s in the direction perpendicular to the c axis at room temperature. The Li ion diffusion coefficient along the c axis direction was found to be very small (6.4 × 10{sup −13} m{sup 2}/s at 333 K), which suggests that the macroscopic diffusion of the Li ion in the β-alumina crystal is mainly two-dimensional. The diffusion coefficient for the same sample was also estimated using NMR line narrowing data and impedance measurements. The impedance data show reasonable agreement with PFG-NMR data, while the line narrowing measurements provided a lower value for the diffusion coefficient. Line narrowing measurements also provided a relatively low value for the activation energy and pre-exponential factor. The temperature dependent diffusion coefficient was obtained in the temperature range 297–333 K by PFG-NMR, from which the activation energy for diffusion of the Li ion was estimated. The activation energy obtained by PFG-NMR was smaller than that obtained by impedance measurements, which suggests that thermally activated defect formation energy exists for 93% Li β-alumina single crystals. The diffusion time dependence of the diffusion coefficient was observed for the Li ion in the 93% Li β-alumina single crystal by means of PFG-NMR experiments. Motion of Li ion in fractal dimension might be a possible explanation for the observed diffusion time dependence of the diffusion coefficient in the 93% Li β–alumina system.

  11. The Effect of Inhomogeneous Sample Susceptibility on Measured Diffusion Anisotropy Using NMR Imaging

    NASA Astrophysics Data System (ADS)

    Trudeau, J. D.; Dixon, W. T.; Hawkins, J.

    1995-07-01

    Water diffusion measurements in white matter of freshly excised pig spinal cord and in parenchyma of fresh celery (excluding the fibers along the edge of the stalk) were performed using NMR at 200 MHz. In white matter of pig spinal cord, the measured diffusion coefficient is anisotropic and independent of sample orientation with respect to the magnetic field, In celery parenchyma, diffusion is isotropic and independent of orientation in the magnetic field when using a diffusion sequence that gives results independent of self-induced magnetic-held gradients. However, when the standard diffusion pulse sequence that gives results dependent upon self-induced magnetic-field gradients is used, diffusion in celery appears isotropic when the stalk is oriented parallel to the magnetic field but anisotropic when oriented perpendicular. Susceptibility variations leading to anisotropic self-induced magnetic-field gradients approximately 3 kHz/cm in magnitude when the celery is oriented perpendicular to the magnetic field can explain this apparent anisotropic diffusion. A study of the apparent diffusion coefficient (ADC) in celery as a function of diffusion times ranging from 8 to 22 ms indicates that the motion is at most only slightly restricted. Therefore, although the effect is not seen in all types of samples, one must be aware that self-induced gradients may affect the ADC and may cause isotropic diffusion to appear anisotropic. In addition, NMR experiments that change diffusion-sensitizing gradient timings to study restricted diffusion change the effects of the self-induced gradients as well as the effect of barriers on the ADC, complicating interpretation.

  12. The use of dielectric and NMR measurements to determine the pore-scale location of organic contaminants. 1997 annual progress report

    SciTech Connect

    Knight, R.; Bryar, T.; Caputi, M.

    1997-07-15

    'The objective of the three-year research project is to investigate the effect of adsorbed organics on the dielectric and nuclear magnetic resonance (NMR) response of porous geological materials. This will allow us to assess the use of dielectric and NMR measurements at a site to determine whether organic contaminants are present in the central volume of the pore space (in a water-wet system) or are adsorbed to the solid surface. In addition, the authors propose to use laboratory dielectric and NMR measurements to study the kinetics of the adsorption and desorption of organics by conducting experiments where the authors control temperature and vary fluid chemistry. This project can be divided into three parts: sample preparation, NMR studies, dielectric studies. Over the past nine months the authors have made significant progress in sample preparation and NMR studies. As the plan is to conduct the NMR and dielectric measurements on the same set of samples, the authors delayed the start of the dielectric measurements until the first stage of NMR measurements were complete. Below the authors summarize the progress in sample preparation and NMR measurements, first briefly introducing the method used for the NMR measurements.'

  13. Measurement of Solution Viscosity via Diffusion-Ordered NMR Spectroscopy (DOSY)

    ERIC Educational Resources Information Center

    Li, Weibin; Kagan, Gerald; Hopson, Russell; Williard, Paul G.

    2011-01-01

    Increasingly, the undergraduate chemistry curriculum includes nuclear magnetic resonance (NMR) spectroscopy. Advanced NMR techniques are often taught including two-dimensional gradient-based experiments. An investigation of intermolecular forces including viscosity, by a variety of methods, is often integrated in the undergraduate physical and…

  14. Electrophoretic separator for purifying biologicals

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Mathematical expressions were developed to describe the interrelationships between operating requirements (capabilities), cell parameters, and system constraints in terms of design criteria definition. The mathematical model was programmed for computer solution. The model was exercised to identify performance-limiting characteristics, and analyses were conducted to predict operation in space of an experiment involving separation of four components. An engineering model of a flowing electrophoretic separator was constructed. The design is directed toward verifying improvements in resolution and throughput of a thicker cell than can be used on earth.

  15. A portable NMR sensor to measure dynamic changes in the amount of water in living stems or fruit and its potential to measure sap flow.

    PubMed

    Windt, Carel W; Blümler, Peter

    2015-04-01

    Nuclear magnetic resonance (NMR) and NMR imaging (magnetic resonance imaging) offer the possibility to quantitatively and non-invasively measure the presence and movement of water. Unfortunately, traditional NMR hardware is expensive, poorly suited for plants, and because of its bulk and complexity, not suitable for use in the field. But does it need to be? We here explore how novel, small-scale portable NMR devices can be used as a flow sensor to directly measure xylem sap flow in a poplar tree (Populus nigra L.), or in a dendrometer-like fashion to measure dynamic changes in the absolute water content of fruit or stems. For the latter purpose we monitored the diurnal pattern of growth, expansion and shrinkage in a model fruit (bean pod, Phaseolus vulgaris L.) and in the stem of an oak tree (Quercus robur L.). We compared changes in absolute stem water content, as measured by the NMR sensor, against stem diameter variations as measured by a set of conventional point dendrometers, to test how well the sensitivities of the two methods compare and to investigate how well diurnal changes in trunk absolute water content correlate with the concomitant diurnal variations in stem diameter. Our results confirm the existence of a strong correlation between the two parameters, but also suggest that dynamic changes in oak stem water content could be larger than is apparent on the basis of the stem diameter variation alone. PMID:25595754

  16. Measuring diffusion-relaxation correlation maps using non-uniform field gradients of single-sided NMR devices

    NASA Astrophysics Data System (ADS)

    Nogueira d'Eurydice, Marcel; Galvosas, Petrik

    2014-11-01

    Single-sided NMR systems are becoming a relevant tool in industry and laboratory environments due to their low cost, low maintenance and capacity to evaluate quantity and quality of hydrogen based materials. The performance of such devices has improved significantly over the last decade, providing increased field homogeneity, field strength and even controlled static field gradients. For a class of these devices, the configuration of the permanent magnets provides a linear variation of the magnetic field and can be used in diffusion measurements. However, magnet design depends directly on its application and, according to the purpose, the field homogeneity may significantly be compromised. This may prevent the determination of diffusion properties of fluids based on the natural inhomogeneity of the field using known techniques. This work introduces a new approach that extends the applicability of diffusion-editing CPMG experiments to NMR devices with highly inhomogeneous magnetic fields, which do not vary linearly in space. Herein, we propose a method to determine a custom diffusion kernel based on the gradient distribution, which can be seen as a signature of each NMR device. This new diffusion kernel is then utilised in the 2D inverse Laplace transform (2D ILT) in order to determine diffusion-relaxation correlation maps of homogeneous multi-phasic fluids. The experiments were performed using NMR MObile Lateral Explore (MOLE), which is a single-sided NMR device designed to maximise the volume at the sweet spot with enhanced depth penetration.

  17. Determination of the biogenic secondary organic aerosol fraction in the boreal forest by AMS and NMR measurements

    NASA Astrophysics Data System (ADS)

    Finessi, E.; Decesari, S.; Paglione, M.; Giulianelli, L.; Carbone, C.; Gilardoni, S.; Fuzzi, S.; Saarikoski, S.; Raatikainen, T.; Hillamo, R.; Allan, J.; Mentel, Th. F.; Tiitta, P.; Laaksonen, A.; Petäjä, T.; Kulmala, M.; Worsnop, D. R.; Facchini, M. C.

    2011-08-01

    The study investigates the sources of fine organic aerosol (OA) in the boreal forest, based on measurements including both filter sampling (PM1) and online methods and carried out during a one-month campaign held in Hyytiälä, Finland, in spring 2007. Two aerosol mass spectrometers (Q-AMS, ToF-AMS) were employed to measure on-line air mass concentrations of major non-refractory aerosol species, while the water extracts of the filter samples were analyzed by nuclear magnetic resonance (NMR) spectroscopy for organic functional group characterization of the polar organic fraction of the aerosol. AMS and NMR spectra were processed separately by non-negative factorization algorithms, in order to apportion the main components underlying the submicrometer organic aerosol composition and depict them in terms of both mass fragmentation patterns and functional group compositions. The NMR results supported the AMS speciation of oxidized organic aerosol (OOA) into two main fractions, which could be generally labelled as more and less oxidized organics. The more oxidized component was characterized by a mass spectrum dominated by the m/z 44 peak, and in parallel by a NMR spectrum showing aromatic and aliphatic backbones highly substituted with oxygenated functional groups (carbonyls/carboxyls and hydroxyls). Such component, contributing on average 50 % of the OA mass throughout the observing period, was associated with pollution outbreaks from the Central Europe. The less oxidized component showed features consistent with less oxygenated aerosols and was enhanced in concomitance with air masses originating from the North-to-West sector, in agreement with previous investigations conducted at this site. NMR factor analysis was able to separate two distinct components under the less oxidized fraction of OA. One of these NMR-factors was associated to the formation of terrestrial biogenic secondary organic aerosol (BSOA), based on the comparison with spectral profiles obtained from

  18. General order parameter based correlation analysis of protein backbone motions between experimental NMR relaxation measurements and molecular dynamics simulations

    SciTech Connect

    Liu, Qing; Shi, Chaowei; Yu, Lu; Zhang, Longhua; Xiong, Ying; Tian, Changlin

    2015-02-13

    Internal backbone dynamic motions are essential for different protein functions and occur on a wide range of time scales, from femtoseconds to seconds. Molecular dynamic (MD) simulations and nuclear magnetic resonance (NMR) spin relaxation measurements are valuable tools to gain access to fast (nanosecond) internal motions. However, there exist few reports on correlation analysis between MD and NMR relaxation data. Here, backbone relaxation measurements of {sup 15}N-labeled SH3 (Src homology 3) domain proteins in aqueous buffer were used to generate general order parameters (S{sup 2}) using a model-free approach. Simultaneously, 80 ns MD simulations of SH3 domain proteins in a defined hydrated box at neutral pH were conducted and the general order parameters (S{sup 2}) were derived from the MD trajectory. Correlation analysis using the Gromos force field indicated that S{sup 2} values from NMR relaxation measurements and MD simulations were significantly different. MD simulations were performed on models with different charge states for three histidine residues, and with different water models, which were SPC (simple point charge) water model and SPC/E (extended simple point charge) water model. S{sup 2} parameters from MD simulations with charges for all three histidines and with the SPC/E water model correlated well with S{sup 2} calculated from the experimental NMR relaxation measurements, in a site-specific manner. - Highlights: • Correlation analysis between NMR relaxation measurements and MD simulations. • General order parameter (S{sup 2}) as common reference between the two methods. • Different protein dynamics with different Histidine charge states in neutral pH. • Different protein dynamics with different water models.

  19. Electrophoretic mobility of oil droplets in electrolyte and surfactant solutions.

    PubMed

    Wuzhang, Jiachen; Song, Yongxin; Sun, Runzhe; Pan, Xinxiang; Li, Dongqing

    2015-10-01

    Electrophoretic mobility of oil droplets of micron sizes in PBS and ionic surfactant solutions was measured in this paper. The experimental results show that, in addition to the applied electric field, the speed and the direction of electrophoretic motion of oil droplets depend on the surfactant concentration and on if the droplet is in negatively charged SDS solutions or in positively charged hexadecyltrimethylammonium bromide (CTAB) solutions. The absolute value of the electrophoretic mobility increases with increased surfactant concentration before the surfactant concentration reaches to the CMC. It was also found that there are two vortices around the oil droplet under the applied electric field. The size of the vortices changes with the surfactant and with the electric field. The vortices around the droplet directly affect the drag of the flow field to the droplet motion and should be considered in the studies of electrophoretic mobility of oil droplets. The existence of the vortices will also influence the determination and the interpretation of the zeta potential of the oil droplets based on the measured mobility data. PMID:26140616

  20. NMR methods for in-situ biofilm metabolism studies: spatial and temporal resolved measurements

    SciTech Connect

    Majors, Paul D.; Mclean, Jeffrey S.; Fredrickson, Jim K.; Wind, Robert A.

    2005-11-01

    We are developing nuclear magnetic resonance (NMR) microscopy, spectroscopy and combined NMR/optical techniques to the study of biofilms. Objectives include: time and depth-resolved metabolite concentrations with isotropic spatial resolution on the order of 10 microns, metabolic pathways and flux rates, mass transport and ultimately their correlation with gene expression by optical microscopy in biofilms. These methods are being developed with Shewanella oneidensis MR-1 as a model system, but are equally applicable to other biofilm systems of interest. Thus, spatially resolved NMR of biofilms is expected to contribute significantly to the understanding of adherent cell metabolism.

  1. Electrophoretic separator for purifying biologicals, part 1

    NASA Technical Reports Server (NTRS)

    Mccreight, L. R.

    1978-01-01

    A program to develop an engineering model of an electrophoretic separator for purifying biologicals is summarized. An extensive mathematical modeling study and numerous ground based tests were included. Focus was placed on developing an actual electrophoretic separator of the continuous flow type, configured and suitable for flight testing as a space processing applications rocket payload.

  2. Lateral diffusion of PEG-Lipid in magnetically aligned bicelles measured using stimulated echo pulsed field gradient 1H NMR.

    PubMed

    Soong, Ronald; Macdonald, Peter M

    2005-01-01

    Lateral diffusion measurements of PEG-lipid incorporated into magnetically aligned bicelles are demonstrated using stimulated echo (STE) pulsed field gradient (PFG) proton (1H) nuclear magnetic resonance (NMR) spectroscopy. Bicelles were composed of dimyristoyl phosphatidylcholine (DMPC) plus dihexanoyl phosphatidylcholine (DHPC) (q = DMPC/DHPC molar ratio = 4.5) plus 1 mol % (relative to DMPC) dimyristoyl phosphatidylethanolamine-N-[methoxy(polyethylene glycol)-2000] (DMPE-PEG 2000) at 25 wt % lipid. 1H NMR STE spectra of perpendicular aligned bicelles contained only resonances assigned to residual HDO and to overlapping contributions from a DMPE-PEG 2000 ethoxy headgroup plus DHPC choline methyl protons. Decay of the latter's STE intensity in the STE PFG 1H NMR experiment (g(z) = 244 G cm(-1)) yielded a DMPE-PEG 2000 (1 mol %, 35 degrees C) lateral diffusion coefficient D = 1.35 x 10(-11) m2 s(-1). Hence, below the "mushroom-to-brush" transition, DMPE-PEG 2000 lateral diffusion is dictated by its DMPE hydrophobic anchor. D was independent of the diffusion time, indicating unrestricted lateral diffusion over root mean-square diffusion distances of microns, supporting the "perforated lamellae" model of bicelle structure under these conditions. Overall, the results demonstrate the feasibility of lateral diffusion measurements in magnetically aligned bicelles using the STE PFG NMR technique. PMID:15475584

  3. The use of dielectric and NMR measurements to determine the pore-scale location of organic. 1998 annual progress report

    SciTech Connect

    Knight, R.

    1998-06-01

    'The objective of the three-year research project is to investigate the effect of adsorbed organics on the dielectric and nuclear magnetic resonance (NMR) response of porous geological materials. This will allow the author to assess the use of dielectric and NMR measurements at a site to determine whether organic contaminants are present in the central volume of the pore space or are adsorbed to the solid surfaces. In addition, she proposes to use laboratory dielectric and NMR measurements to study the kinetics of the adsorption and desorption of organics. This report summarizes work completed after 20 months of a three-year project. The research involves the study of the NMR and dielectric behavior of sands with three types of solid surfaces: water-wet, where water spontaneously coats and adsorbs to the solid surfaces; hydrophobic, where water is repelled from the solid surfaces by an organosilane coating; and oil-wet, where oil coats the solid surfaces. The oil-wet case is representative of a contaminated soil, in which oil has become adsorbed to the solid surfaces.'

  4. Current-Distribution Measurement in Polymer Electrolyte Water Electrolysis Equipment and Polymer Electrolyte Fuel Cell Using NMR Sensor

    NASA Astrophysics Data System (ADS)

    Yokouchi, Yasuo; Ogawa, Kuniyasu; Haishi, Tomoyuki; Ito, Kohei

    In a polymer electrolyte fuel cell (PEFC), the current density through the polymer electrolyte membrane (PEM) is distributed along the electrode on the membrane electrode assembly (MEA). To increase the electric power density of a PEFC, it is necessary to locate local decreases in current density where electric power generation decreases due to a lack of hydrogen, flooding, and so on. Therefore, achieving a higher current density in a PEFC requires monitoring the local current density. We developed a new method to estimate the spatial distribution of current flowing through the MEA in a polymer electrolyte water electrolysis equipment (PEWEE) and a PEFC using Nuclear-Magnetic-Resonance (NMR) sensors. The magnetic field strength induced by current through the MEA in a PEWEE is acquired as the frequency shift of the NMR signal which is measured by the NMR sensor. The spatial distributions of the frequency shifts occurring along the MEA in a PEWEE and a PEFC was measured. In order to verify the method, the magnetic field strength induced by the current through the gas diffusion layer (GDL) in a PEWEE was analyzed theoretically under the assumption that the current through MEA was uniform. The frequency shift was then calculated as a function of the geometry of the GDL, current, and the position of the NMR sensor. From experimental and theoretical results, the frequency shift of the NMR signal is proportional to current density and depends on the position of the sensors. Using the measurement system, we also obtained the current distribution through the GDL in a PEFC generating electric power. In these studies, the experimental and theoretical results agree.

  5. Protein effective rotational correlation times from translational self-diffusion coefficients measured by PFG-NMR.

    PubMed

    Yao, Shenggen; Babon, Jeffrey J; Norton, Raymond S

    2008-08-01

    Molecular rotational correlation times are of interest for many studies carried out in solution, including characterization of biomolecular structure and interactions. Here we have evaluated the estimates of protein effective rotational correlation times from their translational self-diffusion coefficients measured by pulsed-field gradient NMR against correlation times determined from both collective and residue-specific (15)N relaxation analyses and those derived from 3D structure-based hydrodynamic calculations. The results show that, provided the protein diffusive behavior is coherent with the Debye-Stokes-Einstein model, translational diffusion coefficients provide rapid estimates with reasonable accuracy of their effective rotational correlation times. Effective rotational correlation times estimated from translational diffusion coefficients may be particularly beneficial in cases where i) isotopically labelled material is not available, ii) collective backbone (15)N relaxation rates are difficult to interpret because of the presence of flexible termini or loops, or iii) a full relaxation analysis is practically difficult because of limited sensitivity owing to low protein concentration, high molecular mass or low temperatures. PMID:18583018

  6. Studies of 3He polarization losses during NMR and EPR measurment and Polarized 3He target cell lifetime

    NASA Astrophysics Data System (ADS)

    An, Peibo

    2014-09-01

    The 3He target cell polarized by spin-exchange optical pumping(SEOP) is used as a neutron substitute to study the inner structure of the neutron. In our lab, nuclear-magnetic-resonance(NMR) is used to measure the relative polarization and electron-paramagnetic-resonance(EPR) is used to measure the spin exchange EPR frequency shift parameter of potassium and rubidium in our target cell presented in magnetic fields. The alkali in the cell is used to facilitate the polarization of 3He. The first part of my work presents the study of the polarization losses of the cell during both NMR and EPR. With the help of improved RF coils, we keep the background noise received by pickup coils reasonably low, but three other kinds of losses are inevitable: losses during Adiabatic Fast Passage (AFP) sweep, losses due to flux change caused by different cell orientation with respect to RF fields and physical losses. Fortunately there is only flux change in NMR measurements. The second part of my work presents the study of cell lifetime improvement. The polarization decreases in a process called relaxation exponentially. The lifetime of a cell is how long it can keep its polarization. The typical lifetime of cells produced in our lab is about 22 hours. With a newly designed vacuum system. The 3He target cell polarized by spin-exchange optical pumping(SEOP) is used as a neutron substitute to study the inner structure of the neutron. In our lab, nuclear-magnetic-resonance(NMR) is used to measure the relative polarization and electron-paramagnetic-resonance(EPR) is used to measure the spin exchange EPR frequency shift parameter of potassium and rubidium in our target cell presented in magnetic fields. The alkali in the cell is used to facilitate the polarization of 3He. The first part of my work presents the study of the polarization losses of the cell during both NMR and EPR. With the help of improved RF coils, we keep the background noise received by pickup coils reasonably low, but

  7. Sensitivity and resolution of two-dimensional NMR diffusion-relaxation measurements

    NASA Astrophysics Data System (ADS)

    Kausik, Ravinath; Hürlimann, Martin D.

    2016-09-01

    The performance of 2D NMR diffusion-relaxation measurements for fluid typing applications is analyzed. In particular, we delineate the region in the diffusion - relaxation plane that can be determined with a given gradient strength and homogeneity, and compare the performance of the single and double echo encoding with the stimulated echo diffusion encoding. We show that the diffusion editing based approach is able to determine the diffusion coefficient only if the relaxation time T2 exceeds a cutoff value T2,cutoff , that scales like T2,cutoff ∝g - 2 / 3D - 1 / 3 . For stimulated echo encoding, the optimal diffusion encoding times (Td and δ), that provide the best diffusion sensitivity, rely only on the T1 /T2 ratios and not on the diffusion coefficients of the fluids or the applied gradient strengths. Irrespective of T1 , for high enough gradients (i.e. when γ2g2 DT23 >102), the Hahn echo based encoding is superior to encoding based on the stimulated echo. For weaker gradients, the stimulated echo is superior only if the T1 /T2 ratio is much larger than 1. For single component systems, the diffusion sensitivity is not adversely impacted by the uniformity of the gradients and the diffusion distributions can be well measured. The presence of non-uniform gradients can affect the determination of the diffusion distributions when you have two fluids of comparable T2 . In such situations the effective single component diffusion coefficient is always closer to the geometric mean diffusion coefficient of the two fluids.

  8. NMR-based approach to measure the free energy of transmembrane helix-helix interactions.

    PubMed

    Mineev, Konstantin S; Lesovoy, Dmitry M; Usmanova, Dinara R; Goncharuk, Sergey A; Shulepko, Mikhail A; Lyukmanova, Ekaterina N; Kirpichnikov, Mikhail P; Bocharov, Eduard V; Arseniev, Alexander S

    2014-01-01

    Knowledge of the energetic parameters of transmembrane helix-helix interactions is necessary for the establishment of a structure-energy relationship for α-helical membrane domains. A number of techniques have been developed to measure the free energies of dimerization and oligomerization of transmembrane α-helices, and all of these have their advantages and drawbacks. In this study we propose a methodology to determine the magnitudes of the free energy of interactions between transmembrane helices in detergent micelles. The suggested approach employs solution nuclear magnetic resonance (NMR) spectroscopy to determine the population of the oligomeric states of the transmembrane domains and introduces a new formalism to describe the oligomerization equilibrium, which is based on the assumption that both the dimerization of the transmembrane domains and the dissociation of the dimer can occur only upon the collision of detergent micelles. The technique has three major advantages compared with other existing approaches: it may be used to analyze both weak and relatively strong dimerization/oligomerization processes, it works well for the analysis of complex equilibria, e.g. when monomer, dimer and high-order oligomer populations are simultaneously present in the solution, and it can simultaneously yield both structural and energetic characteristics of the helix-helix interaction under study. The proposed methodology was applied to investigate the oligomerization process of transmembrane domains of fibroblast growth factor receptor 3 (FGFR3) and vascular endothelium growth factor receptor 2 (VEGFR2), and allowed the measurement of the free energy of dimerization of both of these objects. In addition the proposed method was able to describe the multi-state oligomerization process of the VEGFR2 transmembrane domain. PMID:24036227

  9. Sensitivity and resolution of two-dimensional NMR diffusion-relaxation measurements

    NASA Astrophysics Data System (ADS)

    Kausik, Ravinath; Hürlimann, Martin D.

    2016-09-01

    The performance of 2D NMR diffusion-relaxation measurements for fluid typing applications is analyzed. In particular, we delineate the region in the diffusion - relaxation plane that can be determined with a given gradient strength and homogeneity, and compare the performance of the single and double echo encoding with the stimulated echo diffusion encoding. We show that the diffusion editing based approach is able to determine the diffusion coefficient only if the relaxation time T2 exceeds a cutoff value T2,cutoff , that scales like T2,cutoff ∝g - 2 / 3D - 1 / 3 . For stimulated echo encoding, the optimal diffusion encoding times (Td and δ), that provide the best diffusion sensitivity, rely only on the T1 /T2 ratios and not on the diffusion coefficients of the fluids or the applied gradient strengths. Irrespective of T1 , for high enough gradients (i.e. when γ2g2DT23 >102), the Hahn echo based encoding is superior to encoding based on the stimulated echo. For weaker gradients, the stimulated echo is superior only if the T1 /T2 ratio is much larger than 1. For single component systems, the diffusion sensitivity is not adversely impacted by the uniformity of the gradients and the diffusion distributions can be well measured. The presence of non-uniform gradients can affect the determination of the diffusion distributions when you have two fluids of comparable T2 . In such situations the effective single component diffusion coefficient is always closer to the geometric mean diffusion coefficient of the two fluids.

  10. Sensitivity and resolution of two-dimensional NMR diffusion-relaxation measurements.

    PubMed

    Kausik, Ravinath; Hürlimann, Martin D

    2016-09-01

    The performance of 2D NMR diffusion-relaxation measurements for fluid typing applications is analyzed. In particular, we delineate the region in the diffusion - relaxation plane that can be determined with a given gradient strength and homogeneity, and compare the performance of the single and double echo encoding with the stimulated echo diffusion encoding. We show that the diffusion editing based approach is able to determine the diffusion coefficient only if the relaxation time T2 exceeds a cutoff value T2,cutoff, that scales like T2,cutoff∝g(-2/3)D(-1/3). For stimulated echo encoding, the optimal diffusion encoding times (Td and δ), that provide the best diffusion sensitivity, rely only on the T1/T2 ratios and not on the diffusion coefficients of the fluids or the applied gradient strengths. Irrespective of T1, for high enough gradients (i.e. when γ(2)g(2)DT2(3)>10(2)), the Hahn echo based encoding is superior to encoding based on the stimulated echo. For weaker gradients, the stimulated echo is superior only if the T1/T2 ratio is much larger than 1. For single component systems, the diffusion sensitivity is not adversely impacted by the uniformity of the gradients and the diffusion distributions can be well measured. The presence of non-uniform gradients can affect the determination of the diffusion distributions when you have two fluids of comparable T2. In such situations the effective single component diffusion coefficient is always closer to the geometric mean diffusion coefficient of the two fluids. PMID:27389638

  11. Solute diffusion in ionic liquids, NMR measurements and comparisons to conventional solvents.

    PubMed

    Kaintz, Anne; Baker, Gary; Benesi, Alan; Maroncelli, Mark

    2013-10-01

    Diffusion coefficients of a variety of dilute solutes in the series of 1-alkyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imides ([Prn1][Tf2N], n = 3, 4, 6, 8, and 10), trihexyltetracedecylphosphonium bis(trifluoromethanesulfonyl)imide [P14,666][Tf2N], and assorted imidazolium ionic liquids are measured using pulsed field gradient (1)H NMR. These data, combined with available literature data, are used to try to uncover the solute and solvent characteristics most important in determining tracer diffusion rates. Discussion is framed in terms of departures from simple hydrodynamic predictions for translational friction using the ratio ζobs/ζSE, where ζobs is the observed friction, determined from the measured diffusion coefficient D via ζobs = kBT/D, and ζSE = 6πηR is the Stokes friction on a sphere of radius R (determined from the solute van der Waals volume) in a solvent with viscosity η. In the case of neutral solutes, the primary determinant of whether hydrodynamic predictions are accurate is the relative size of solute versus solvent molecules. A single correlation, albeit with considerable scatter, is found between ζobs/ζSE and the ratio of solute-to-solvent van der Waals volumes, ζobs/ζSE = {1 + a(VU/VV)(-p)}, with constants a = 1.93 and p = 1.88. In the case of small solutes, the observed friction is over 100-fold smaller than predictions of hydrodynamic models. The dipole moment of the solute has little effect on the friction, whereas solute charge has a marked effect. For monovalent solutes of size comparable to or smaller than the solvent ions, the observed friction is comparable to or even greater than what is predicted by hydrodynamics. These general trends are shown to be quite similar to what is observed for tracer diffusion in conventional solvents. PMID:23968276

  12. Properties of sesame oil by detailed 1H and 13C NMR assignments before and after ozonation and their correlation with iodine value, peroxide value, and viscosity measurements.

    PubMed

    Sega, Alessandro; Zanardi, Iacopo; Chiasserini, Luisa; Gabbrielli, Alessandro; Bocci, Velio; Travagli, Valter

    2010-02-01

    Gaseous ozone chemically reacts with unsaturated triglyceride substrates leading to ozonated derivatives with a wide potential applications, ranging from the petrochemical to the pharmaceutical industry. To date, an ultimate understanding of the ozone reactivity during sesame oil ozonation process as well as detailed (1)H and (13)C NMR assignments are lacking. A practical advantage of NMR is that a single NMR sample measurement can explain many issues, while similar analysis by traditional methods may require several independent and time-consuming measurements. Moreover, significant relationships among NMR spectra and both conventional chemical analysis and viscosity measurements have been found. Eventually, NMR could play an important role for quality attributes of ozonated oil derivatives. PMID:19900426

  13. A compact high-performance low-field NMR apparatus for measurements on fluids at very high pressures and temperatures

    SciTech Connect

    Freedman, R.; Anand, V. Ganesan, K.; Tabrizi, P.; Torres, R.; Grant, B.; Catina, D.; Ryan, D.; Borman, C.; Krueckl, C.

    2014-02-15

    We discuss an innovative new high-performance apparatus for performing low-field Nuclear Magnetic Resonance (NMR) relaxation times and diffusion measurements on fluids at very high pressures and high temperatures. The apparatus sensor design and electronics specifications allow for dual deployment either in a fluid sampling well logging tool or in a laboratory. The sensor and electronics were designed to function in both environments. This paper discusses the use of the apparatus in a laboratory environment. The operating temperature and pressure limits, and the signal-to-noise ratio (SNR) of the new system exceed by a very wide margin what is currently possible. This major breakthrough was made possible by a revolutionary new sensor design that breaks many of the rules of conventional high pressure NMR sensor design. A metallic sample holder capable of operating at high pressures and temperatures is provided to contain the fluid under study. The sample holder has been successfully tested for operation up to 36 Kpsi. A solenoid coil wound on a slotted titanium frame sits inside the metallic sample holder and serves as an antenna to transmit RF pulses and receive NMR signals. The metal sample holder is sandwiched between a pair of gradient coils which provide a linear field gradient for pulsed field gradient diffusion measurements. The assembly sits in the bore of a low-gradient permanent magnet. The system can operate over a wide frequency range without the need for tuning the antenna to the Larmor frequency. The SNR measured on a water sample at room temperature is more than 15 times greater than that of the commercial low-field system in our laboratory. Thus, the new system provides for data acquisition more than 200 times faster than was previously possible. Laboratory NMR measurements of relaxations times and diffusion coefficients performed at pressures up to 25 Kpsi and at temperatures up to 175 °C with crude oils enlivened with dissolved hydrocarbon gases

  14. A compact high-performance low-field NMR apparatus for measurements on fluids at very high pressures and temperatures.

    PubMed

    Freedman, R; Anand, V; Grant, B; Ganesan, K; Tabrizi, P; Torres, R; Catina, D; Ryan, D; Borman, C; Krueckl, C

    2014-02-01

    We discuss an innovative new high-performance apparatus for performing low-field Nuclear Magnetic Resonance (NMR) relaxation times and diffusion measurements on fluids at very high pressures and high temperatures. The apparatus sensor design and electronics specifications allow for dual deployment either in a fluid sampling well logging tool or in a laboratory. The sensor and electronics were designed to function in both environments. This paper discusses the use of the apparatus in a laboratory environment. The operating temperature and pressure limits, and the signal-to-noise ratio (SNR) of the new system exceed by a very wide margin what is currently possible. This major breakthrough was made possible by a revolutionary new sensor design that breaks many of the rules of conventional high pressure NMR sensor design. A metallic sample holder capable of operating at high pressures and temperatures is provided to contain the fluid under study. The sample holder has been successfully tested for operation up to 36 Kpsi. A solenoid coil wound on a slotted titanium frame sits inside the metallic sample holder and serves as an antenna to transmit RF pulses and receive NMR signals. The metal sample holder is sandwiched between a pair of gradient coils which provide a linear field gradient for pulsed field gradient diffusion measurements. The assembly sits in the bore of a low-gradient permanent magnet. The system can operate over a wide frequency range without the need for tuning the antenna to the Larmor frequency. The SNR measured on a water sample at room temperature is more than 15 times greater than that of the commercial low-field system in our laboratory. Thus, the new system provides for data acquisition more than 200 times faster than was previously possible. Laboratory NMR measurements of relaxations times and diffusion coefficients performed at pressures up to 25 Kpsi and at temperatures up to 175 °C with crude oils enlivened with dissolved hydrocarbon gases

  15. A compact high-performance low-field NMR apparatus for measurements on fluids at very high pressures and temperatures

    NASA Astrophysics Data System (ADS)

    Freedman, R.; Anand, V.; Grant, B.; Ganesan, K.; Tabrizi, P.; Torres, R.; Catina, D.; Ryan, D.; Borman, C.; Krueckl, C.

    2014-02-01

    We discuss an innovative new high-performance apparatus for performing low-field Nuclear Magnetic Resonance (NMR) relaxation times and diffusion measurements on fluids at very high pressures and high temperatures. The apparatus sensor design and electronics specifications allow for dual deployment either in a fluid sampling well logging tool or in a laboratory. The sensor and electronics were designed to function in both environments. This paper discusses the use of the apparatus in a laboratory environment. The operating temperature and pressure limits, and the signal-to-noise ratio (SNR) of the new system exceed by a very wide margin what is currently possible. This major breakthrough was made possible by a revolutionary new sensor design that breaks many of the rules of conventional high pressure NMR sensor design. A metallic sample holder capable of operating at high pressures and temperatures is provided to contain the fluid under study. The sample holder has been successfully tested for operation up to 36 Kpsi. A solenoid coil wound on a slotted titanium frame sits inside the metallic sample holder and serves as an antenna to transmit RF pulses and receive NMR signals. The metal sample holder is sandwiched between a pair of gradient coils which provide a linear field gradient for pulsed field gradient diffusion measurements. The assembly sits in the bore of a low-gradient permanent magnet. The system can operate over a wide frequency range without the need for tuning the antenna to the Larmor frequency. The SNR measured on a water sample at room temperature is more than 15 times greater than that of the commercial low-field system in our laboratory. Thus, the new system provides for data acquisition more than 200 times faster than was previously possible. Laboratory NMR measurements of relaxations times and diffusion coefficients performed at pressures up to 25 Kpsi and at temperatures up to 175 °C with crude oils enlivened with dissolved hydrocarbon gases

  16. High resolution NMR measurements using a 400 MHz NMR with an (RE)Ba2Cu3O7-x high-temperature superconducting inner coil: Towards a compact super-high-field NMR

    NASA Astrophysics Data System (ADS)

    Piao, R.; Iguchi, S.; Hamada, M.; Matsumoto, S.; Suematsu, H.; Saito, A. T.; Li, J.; Nakagome, H.; Takao, T.; Takahashi, M.; Maeda, H.; Yanagisawa, Y.

    2016-02-01

    Use of high-temperature superconducting (HTS) inner coils in combination with conventional low-temperature superconducting (LTS) outer coils for an NMR magnet, i.e. a LTS/HTS NMR magnet, is a suitable option to realize a high-resolution NMR spectrometer with operating frequency >1 GHz. From the standpoint of creating a compact magnet, (RE: Rare earth) Ba2Cu3O7-x (REBCO) HTS inner coils which can tolerate a strong hoop stress caused by a Lorentz force are preferred. However, in our previous work on a first-generation 400 MHz LTS/REBCO NMR magnet, the NMR resolution and sensitivity were about ten times worse than that of a conventional LTS NMR magnet. The result was caused by a large field inhomogeneity in the REBCO coil itself and the shielding effect of a screening current induced in that coil. In the present paper, we describe the operation of a modified 400 MHz LTS/REBCO NMR magnet with an advanced field compensation technology using a combination of novel ferromagnetic shimming and an appropriate procedure for NMR spectrum line shape optimization. We succeeded in obtaining a good NMR line shape and 2D NOESY spectrum for a lysozyme aqueous sample. We believe that this technology is indispensable for the realization of a compact super-high-field high-resolution NMR.

  17. Solution NMR Experiment for Measurement of (15)N-(1)H Residual Dipolar Couplings in Large Proteins and Supramolecular Complexes.

    PubMed

    Eletsky, Alexander; Pulavarti, Surya V S R K; Beaumont, Victor; Gollnick, Paul; Szyperski, Thomas

    2015-09-01

    NMR residual dipolar couplings (RDCs) are exquisite probes of protein structure and dynamics. A new solution NMR experiment named 2D SE2 J-TROSY is presented to measure N-H RDCs for proteins and supramolecular complexes in excess of 200 kDa. This enables validation and refinement of their X-ray crystal and solution NMR structures and the characterization of structural and dynamic changes occurring upon complex formation. Accurate N-H RDCs were measured at 750 MHz (1)H resonance frequency for 11-mer 93 kDa (2)H,(15)N-labeled Trp RNA-binding attenuator protein tumbling with a correlation time τc of 120 ns. This is about twice as long as that for the most slowly tumbling system, for which N-H RDCs could be measured, so far, and corresponds to molecular weights of ∼200 kDa at 25 °C. Furthermore, due to the robustness of SE2 J-TROSY with respect to residual (1)H density from exchangeable protons, increased sensitivity at (1)H resonance frequencies around 1 GHz promises to enable N-H RDC measurement for even larger systems. PMID:26293598

  18. Measuring translational diffusion coefficients of peptides and proteins by PFG-NMR using band-selective RF pulses.

    PubMed

    Yao, Shenggen; Weber, Daniel K; Separovic, Frances; Keizer, David W

    2014-07-01

    Molecular translational self-diffusion, a measure of diffusive motion, provides information on the effective molecular hydrodynamic radius, as well as information on the properties of media or solution through which the molecule diffuses. Protein translational diffusion measured by pulsed-field gradient nuclear magnetic resonance (PFG-NMR) has seen increased application in structure and interaction studies, as structural changes or protein-protein interactions are often accompanied by alteration of their effective hydrodynamic radii. Unlike the analysis of complex mixtures by PFG-NMR, for monitoring changes of protein translational diffusion under various conditions, such as different stages of folding/unfolding, a partial region of the spectrum or even a single resonance is sufficient. We report translational diffusion coefficients measured by PFG-NMR with a modified stimulated echo (STE) sequence where band-selective pulses are employed for all three (1)H RF pulses. Compared with conventional non-selective sequence, e.g. the BPP-LED sequence, the advantage of this modified band-selective excitation short transient (BEST) version of STE (BEST-STE) sequence is multi-fold, namely: (1) potential sensitivity gain as in generalized BEST-based sequences, (2) water suppression is no longer required as the magnetization of solvent water is not perturbed during the measurement, and (3) dynamic range problems due to the presence of intense resonances from molecules other than the protein or peptide of interest, such as non-deuterated detergent micelles, are avoided. PMID:24824112

  19. Measurement of regional cerebral blood flow in cat brain using intracarotid 2H2O and 2H NMR imaging

    SciTech Connect

    Detre, J.A.; Subramanian, V.H.; Mitchell, M.D.; Smith, D.S.; Kobayashi, A.; Zaman, A.; Leigh, J.S. Jr. )

    1990-05-01

    Cerebral blood flow (CBF) was measured in cat brain in vivo at 2.7 T using 2H NMR to monitor the washout of deuterated saline injected into both carotid arteries via the lingual arteries. In anesthetized cats, global CBF varied directly with PaCO{sub 2} over a range of 20-50 mm Hg, and the corresponding global CBF values ranged from 25 to 125 ml.100 g-1.min-1. Regional CBF was measured in a 1-cm axial section of cat brain using intracarotid deuterated saline and gradient-echo 2H NMR imaging. Blood flow images with a maximum pixel resolution of 0.3 x 0.3 x 1.0 cm were generated from the deuterium signal washout at each pixel. Image derived values for CBF agreed well with other determinations, and decreased significantly with hypocapnia.

  20. Increasing the sensitivity of NMR diffusion measurements by paramagnetic longitudinal relaxation enhancement, with application to ribosome–nascent chain complexes

    PubMed Central

    Cassaignau, Anaïs M. E.; Cabrita, Lisa D.

    2016-01-01

    The translational diffusion of macromolecules can be examined non-invasively by stimulated echo (STE) NMR experiments to accurately determine their molecular sizes. These measurements can be important probes of intermolecular interactions and protein folding and unfolding, and are crucial in monitoring the integrity of large macromolecular assemblies such as ribosome–nascent chain complexes (RNCs). However, NMR studies of these complexes can be severely constrained by their slow tumbling, low solubility (with maximum concentrations of up to 10 μM), and short lifetimes resulting in weak signal, and therefore continuing improvements in experimental sensitivity are essential. Here we explore the use of the paramagnetic longitudinal relaxation enhancement (PLRE) agent NiDO2A on the sensitivity of 15N XSTE and SORDID heteronuclear STE experiments, which can be used to monitor the integrity of these unstable complexes. We exploit the dependence of the PLRE effect on the gyromagnetic ratio and electronic relaxation time to accelerate recovery of 1H magnetization without adversely affecting storage on Nz during diffusion delays or introducing significant transverse relaxation line broadening. By applying the longitudinal relaxation-optimized SORDID pulse sequence together with NiDO2A to 70S Escherichia coli ribosomes and RNCs, NMR diffusion sensitivity enhancements of up to 4.5-fold relative to XSTE are achieved, alongside ~1.9-fold improvements in two-dimensional NMR sensitivity, without compromising the sample integrity. We anticipate these results will significantly advance the use of NMR to probe dynamic regions of ribosomes and other large, unstable macromolecular assemblies. PMID:26253948

  1. Electrophoretic cell separation by means of microspheres

    NASA Technical Reports Server (NTRS)

    Smolka, A. J. K.; Nerren, B. H.; Margel, S.; Rembaum, A.

    1979-01-01

    The electrophoretic mobility of fixed human erythrocytes immunologically labeled with poly(vinylpyridine) or poly(glutaraldehyde) microspheres was reduced by approximately 40%. This observation was utilized in preparative scale electrophoretic separations of fixed human and turkey erythrocytes, the mobilities of which under normal physiological conditions do not differ sufficiently to allow their separation by continuous flow electrophoresis. We suggest that resolution in the electrophoretic separation of cell subpopulations, currently limited by finite and often overlapping mobility distributions, may be significantly enhanced by immunospecific labeling of target populations using microspheres.

  2. Dynamic NMR microscopy measurement of the dynamics and flow partitioning of colloidal particles in a bifurcation

    NASA Astrophysics Data System (ADS)

    Fridjonsson, Einar O.; Seymour, Joseph D.; Cokelet, Giles R.; Codd, Sarah L.

    2011-05-01

    The flow and distribution of Newtonian, polymeric and colloid suspension fluids at low Reynolds numbers in bifurcations has importance in a wide range of disciplines, including microvascular physiology and microfluidic devices. A bifurcation consisting of circular capillaries laser etched into a hard polymer with inlet diameter 2.50 ± 0.01 mm, bifurcating to a small diameter outlet of 0.76 ± 0.01 mm and a large diameter outlet of 1.25 ± 0.01 mm is examined. Four distinct fluids (water, 0.25%wt xanthan gum, 8 and 22%vol hard-sphere colloidal suspensions) are flowed at flow rates from 10 to 30 ml/h corresponding to Reynolds numbers based on the entry flow from 0.001 to 8. PGSE NMR techniques are applied to obtain dynamic images of the fluids inside the bifurcation with spatial resolution of 59 × 59 μm/pixel in plane over a 200-μm-thick slice. Velocity in all three spatial directions is examined to determine the impact of secondary flows and characterize the transport in the bifurcation. The velocity data provide direct measurement of the volumetric distribution of the flow between the two channels as a function of flow rate. Water and the 8% colloidal suspension show a constant distribution with increasing flow rate, the xanthan gum shows an increase in fluid going into the larger outlet with higher flow rate, and the 22% colloidal suspension shows a decrease in fluid entering the larger channel with higher flow rate. For the colloidal particle flow, the distribution of colloid particles down the capillary is determined by examining the spectrally resolved propagator for the oil inside the core-shell particles in a direction perpendicular to the axial flow. Using dynamic magnetic resonance microscopy, the potential for using magnetic resonance for "particle counting" in a microscale bifurcation is thus demonstrated.

  3. Two-dimensional NMR measurement and point dipole model prediction of paramagnetic shift tensors in solids

    NASA Astrophysics Data System (ADS)

    Walder, Brennan J.; Dey, Krishna K.; Davis, Michael C.; Baltisberger, Jay H.; Grandinetti, Philip J.

    2015-01-01

    A new two-dimensional Nuclear Magnetic Resonance (NMR) experiment to separate and correlate the first-order quadrupolar and chemical/paramagnetic shift interactions is described. This experiment, which we call the shifting-d echo experiment, allows a more precise determination of tensor principal components values and their relative orientation. It is designed using the recently introduced symmetry pathway concept. A comparison of the shifting-d experiment with earlier proposed methods is presented and experimentally illustrated in the case of 2H (I = 1) paramagnetic shift and quadrupolar tensors of CuCl2ṡ2D2O. The benefits of the shifting-d echo experiment over other methods are a factor of two improvement in sensitivity and the suppression of major artifacts. From the 2D lineshape analysis of the shifting-d spectrum, the 2H quadrupolar coupling parameters are = 118.1 kHz and <ηq> = 0.88, and the 2H paramagnetic shift tensor anisotropy parameters are <ζP> = - 152.5 ppm and <ηP> = 0.91. The orientation of the quadrupolar coupling principal axis system (PAS) relative to the paramagnetic shift anisotropy principal axis system is given by ( α , β , γ ) = ( /π 2 , /π 2 , 0 ) . Using a simple ligand hopping model, the tensor parameters in the absence of exchange are estimated. On the basis of this analysis, the instantaneous principal components and orientation of the quadrupolar coupling are found to be in excellent agreement with previous measurements. A new point dipole model for predicting the paramagnetic shift tensor is proposed yielding significantly better agreement than previously used models. In the new model, the dipoles are displaced from nuclei at positions associated with high electron density in the singly occupied molecular orbital predicted from ligand field theory.

  4. Backbone dynamics of the oligomerization domain of p53 determined from 15N NMR relaxation measurements.

    PubMed

    Clubb, R T; Omichinski, J G; Sakaguchi, K; Appella, E; Gronenborn, A M; Clore, G M

    1995-05-01

    The backbone dynamics of the tetrameric p53 oligomerization domain (residues 319-360) have been investigated by two-dimensional inverse detected heteronuclear 1H-15N NMR spectroscopy at 500 and 600 MHz. 15N T1, T2, and heteronuclear NOEs were measured for 39 of 40 non-proline backbone NH vectors at both field strengths. The overall correlation time for the tetramer, calculated from the T1/T2 ratios, was found to be 14.8 ns at 35 degrees C. The correlation times and amplitudes of the internal motions were extracted from the relaxation data using the model-free formalism (Lipari G, Szabo A, 1982, J Am Chem Soc 104:4546-4559). The internal dynamics of the structural core of the p53 oligomerization domain are uniform and fairly rigid, with residues 327-354 exhibiting an average generalized order parameter (S2) of 0.88 +/- 0.08. The N- and C-termini exhibit substantial mobility and are unstructured in the solution structure of p53. Residues located at the N- and C-termini, in the beta-sheet, in the turn between the alpha-helix and beta-sheet, and at the C-terminal end of the alpha-helix display two distinct internal motions that are faster than the overall correlation time. Fast internal motions (< or = 20 ps) are within the extreme narrowing limit and are of uniform amplitude. The slower motions (0.6-2.2 ns) are outside the extreme narrowing limit and vary in amplitude.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7663341

  5. Comparison of double-quantum NMR normalization schemes to measure homonuclear dipole-dipole interactions

    SciTech Connect

    Saalwächter, Kay

    2014-08-14

    A recent implementation of a double-quantum (DQ) recoupling solid-state NMR experiment, dubbed DQ-DRENAR, provides a quantitative measure of homonuclear dipole-dipole coupling constants in multispin-1/2 systems. It was claimed to be more robust than another, previously known experiment relying on the recording of point-by-point normalized DQ build-up curves. Focusing on the POST-C7 and BaBa-xy16 DQ pulse sequences, I here present an in-depth comparison of both approaches based upon spin-dynamics simulations, stressing that they are based upon very similar principles and that they are largely equivalent when no imperfections are present. With imperfections, it is found that DQ-DRENAR/POST-C7 does not fully compensate for additional signal dephasing related to chemical shifts (CS) and their anisotropy (CSA), which over-compensates the intrinsic CS(A)-related efficiency loss of the DQ Hamiltonian and leads to an apparent cancellation effect. The simulations further show that the CS(A)-related dephasing in DQ-DRENAR can be removed by another phase cycle step or an improved super-cycled wideband version. Only the latter, or the normalized DQ build-up, are unaffected by CS(A)-related signal loss and yield clean pure dipolar-coupling information subject to unavoidable, pulse sequence specific performance reduction related to higher-order corrections of the dipolar DQ Hamiltonian. The intrinsically super-cycled BaBa-xy16 is shown to exhibit virtually no CS(A) related imperfection terms, but its dipolar performance is somewhat more challenged by CS(A) effects than POST-C7, which can however be compensated when applied at very fast MAS (>50 kHz). Practically, DQ-DRENAR uses a clever phase cycle separation to achieve a significantly shorter experimental time, which can also be beneficially employed in normalized DQ build-up experiments.

  6. 21 CFR 864.7440 - Electrophoretic hemoglobin analysis system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Electrophoretic hemoglobin analysis system. 864....7440 Electrophoretic hemoglobin analysis system. (a) Identification. An electrophoretic hemoglobin analysis system is a device that electrophoretically separates and identifies normal and...

  7. Surface-NMR measurements of the longitudinal relaxation time T1 in a homogeneous sand aquifer in Skive, Denmark

    NASA Astrophysics Data System (ADS)

    Walbrecker, Jan O.; Behroozmand, Ahmad A.

    2012-12-01

    Surface nuclear magnetic resonance (surface NMR) is a geophysical technique used in the exploration of shallow aquifers. It is based on measuring the NMR response of water molecules to excitation by electromagnetic pulses. By increasing the moment of applied pulses, successively deeper regions of an aquifer can be probed. The longitudinal relaxation time T1, determined from the NMR experiment, depends on pore size and can be potentially used to estimate hydraulic conductivity. A novel scheme was recently proposed that was shown theoretically to be more reliable for acquiring surface-NMR T1 data than traditional acquisition. In this proof-of-concept study we provide the first empirical evidence for the superiority of the novel scheme. We chose a survey site close to Skive, Denmark, where proximate boreholes indicate a homogeneous sandy aquifer in the top 30 m. The homogeneous composition implies that the distribution of pore sizes does not vary significantly across the formation. Because pore size is reflected by the T1 relaxation time, we therefore assume that the homogeneous aquifer can be characterized by a single T1 independent of the applied pulse moment (i.e., sampled depth region)—this is the benchmark condition we tested with our surface-NMR measurements. We collected surface-NMR T1 data employing the traditional as well as the novel acquisition scheme at various pulse moments. For each pulse moment we infer a T1 relaxation time based on extensively sampled data (14 delay-time data points). The T1 relaxation times obtained using the novel scheme show a constant value of about 820 ms (± 38 ms) for all pulse moments. In contrast, the T1 relaxation times determined using the traditional scheme vary significantly between 530 and 750 ms with pulse moment, which in an inversion would result in a spatial variation of T1 across the aquifer. The results based on the novel scheme are consistent with a homogeneous aquifer, which we expect based on the borehole

  8. Rapid amide proton exchange rates in peptides and proteins measured by solvent quenching and two-dimensional NMR.

    PubMed Central

    Zhang, Y. Z.; Paterson, Y.; Roder, H.

    1995-01-01

    In an effort to develop a more versatile quenched hydrogen exchange method for studies of peptide conformation and protein-ligand interactions, the mechanism of amide proton exchange for model peptides in DMSO-D2O mixtures was investigated by NMR methods. As in water, H-D exchange rates in the presence of 90% or 95% DMSO exhibit characteristic acid- and base-catalyzed processes and negligible water catalysis. However, the base-catalyzed rate is suppressed by as much as four orders of magnitude in 95% DMSO. As a result, the pH at which the exchange rate goes through a minimum is shifted up by about two pH units and the minimum exchange rate is approximately 100-fold reduced relative to that in D2O. The solvent-dependent decrease in base-catalyzed exchange rates can be attributed primarily to a large increase in pKa values for the NH group, whereas solvent effects on pKW seem less important. Addition of toluene and cyclohexane resulted in improved proton NMR chemical shift dispersion. The dramatic reduction in exchange rates observed in the solvent mixture at optimal pH makes it possible to apply 2D NMR for NH exchange measurements on peptides under conditions where rates are too rapid for direct NMR analysis. To test this solvent-quenching method, melittin was exchanged in D2O (pH 3.2, 12 degrees C), aliquots were quenched by rapid freezing, lyophilized, and dissolved in quenching buffer (70% DMSO, 25% toluene, 4% D2O, 1% cyclohexane, 75 mM dichloroacetic acid) for NMR analysis. Exchange rates for 21 amide protons were measured by recording 2D NMR spectra on a series of samples quenched at different times. The results are consistent with a monomeric unfolded conformation of melittin at acidic pH. The ability to trap labile protons by solvent quenching makes it possible to extend amide protection studies to peptide ligands or labile protons on the surface of a protein involved in macromolecular interactions. PMID:7613478

  9. Uncertainty measurement for automated macro program-processed quantitative proton NMR spectra.

    PubMed

    Hays, Patrick A; Schoenberger, Torsten

    2014-11-01

    The evaluation of a fully automated quantitative proton nuclear magnetic resonance spectroscopy (qNMR) processing program, including the determination of its processing uncertainty, and the calculations of the combined uncertainty of the qNMR result, is presented with details on the use of a trimmed purity average. Quantitative NMR spectra (1359) were collected over a 4-month period on various concentrations of pseudoephedrine HCl dissolved in D2O (0.0610 to 93.60 mg/mL) containing maleic acid (the internal standard) to yield signal-to-noise ratios ranging from 3 to 72,000 for analyte integral regions. The resulting 5436 purities exhibited a normal distribution about the best estimate of the true value. The median absolute deviation (MAD) statistical method was used to obtain a model of uncertainty relative to the signal-to-noise of the analyte's integral peaks. The model was then tested using different concentrations of known purity chloroquine diphosphate. qNMR results of numerous illicit heroin HCl samples were compared to those obtained by capillary electrophoresis. PMID:25273593

  10. In situ measurement of molecular diffusion during catalytic reaction by pulsed-field gradient NMR spectroscopy

    SciTech Connect

    Hong, Y.; Kaerger, J.; Hunger, B. ); Feoktistova, N.N.; Zhdanov, S.P. )

    1992-09-01

    Pulsed-field gradient (PFG) NMR spectroscopy is applied to study the intracrystalline diffusivity of the reactant and product molecules during the conversion of cyclopropane to propene in Zeolite X. The diffusivities are found to be large enough that any influence of intracrystalline diffusion on the overall reaction in flow reactors may be excluded.

  11. CAPILLARY ELECTROPHORETIC BEHAVIOR OF SEVEN SULFONYLUREAS

    EPA Science Inventory

    The electrophoretic behavior of bensulfuron Me, sulfometuron Me, nicosulfuron (Accent), chlorimuron Et, thifensulfuron Me (Harmony), metsulfuron Me, and chlorsulfuron was studied under capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) conditio...

  12. Automated Parallel Capillary Electrophoretic System

    DOEpatents

    Li, Qingbo; Kane, Thomas E.; Liu, Changsheng; Sonnenschein, Bernard; Sharer, Michael V.; Kernan, John R.

    2000-02-22

    An automated electrophoretic system is disclosed. The system employs a capillary cartridge having a plurality of capillary tubes. The cartridge has a first array of capillary ends projecting from one side of a plate. The first array of capillary ends are spaced apart in substantially the same manner as the wells of a microtitre tray of standard size. This allows one to simultaneously perform capillary electrophoresis on samples present in each of the wells of the tray. The system includes a stacked, dual carousel arrangement to eliminate cross-contamination resulting from reuse of the same buffer tray on consecutive executions from electrophoresis. The system also has a gel delivery module containing a gel syringe/a stepper motor or a high pressure chamber with a pump to quickly and uniformly deliver gel through the capillary tubes. The system further includes a multi-wavelength beam generator to generate a laser beam which produces a beam with a wide range of wavelengths. An off-line capillary reconditioner thoroughly cleans a capillary cartridge to enable simultaneous execution of electrophoresis with another capillary cartridge. The streamlined nature of the off-line capillary reconditioner offers the advantage of increased system throughput with a minimal increase in system cost.

  13. Longitudinal NMR parameter measurements of Japanese pear fruit during the growing process using a mobile magnetic resonance imaging system

    NASA Astrophysics Data System (ADS)

    Geya, Yuto; Kimura, Takeshi; Fujisaki, Hirotaka; Terada, Yasuhiko; Kose, Katsumi; Haishi, Tomoyuki; Gemma, Hiroshi; Sekozawa, Yoshihiko

    2013-01-01

    Longitudinal nuclear magnetic resonance (NMR) parameter measurements of Japanese pear fruit (Pyrus pyrifolia Nakai, Kosui) were performed using an electrically mobile magnetic resonance imaging (MRI) system with a 0.2 T and 16 cm gap permanent magnet. To measure the relaxation times and apparent diffusion coefficients of the pear fruit in relation to their weight, seven pear fruits were harvested almost every week during the cell enlargement period and measured in a research orchard. To evaluate the in situ relaxation times, six pear fruits were longitudinally measured for about two months during the same period. The measurements for the harvested samples showed good agreement with the in situ measurements. From the measurements of the harvested samples, it is clear that the relaxation rates of the pear fruits linearly change with the inverse of the linear dimension of the fruits, demonstrating that the relaxation mechanism is a surface relaxation. We therefore conclude that the mobile MRI system is a useful device for measuring the NMR parameters of outdoor living plants.

  14. SVD-Based Technique for Interference Cancellation and Noise Reduction in NMR Measurement of Time-Dependent Magnetic Fields

    PubMed Central

    Chen, Wenjun; Ma, Hong; Yu, De; Zhang, Hua

    2016-01-01

    A nuclear magnetic resonance (NMR) experiment for measurement of time-dependent magnetic fields was introduced. To improve the signal-to-interference-plus-noise ratio (SINR) of NMR data, a new method for interference cancellation and noise reduction (ICNR) based on singular value decomposition (SVD) was proposed. The singular values corresponding to the radio frequency interference (RFI) signal were identified in terms of the correlation between the FID data and the reference data, and then the RFI and noise were suppressed by setting the corresponding singular values to zero. The validity of the algorithm was verified by processing the measured NMR data. The results indicated that, this method has a significantly suppression of RFI and random noise, and can well preserve the FID signal. At present, the major limitation of the proposed SVD-based ICNR technique is that the threshold value for interference cancellation needs to be manually selected. Finally, the inversion waveform of the applied alternating magnetic field was given by fitting the processed experimental data. PMID:26959024

  15. SVD-Based Technique for Interference Cancellation and Noise Reduction in NMR Measurement of Time-Dependent Magnetic Fields.

    PubMed

    Chen, Wenjun; Ma, Hong; Yu, De; Zhang, Hua

    2016-01-01

    A nuclear magnetic resonance (NMR) experiment for measurement of time-dependent magnetic fields was introduced. To improve the signal-to-interference-plus-noise ratio (SINR) of NMR data, a new method for interference cancellation and noise reduction (ICNR) based on singular value decomposition (SVD) was proposed. The singular values corresponding to the radio frequency interference (RFI) signal were identified in terms of the correlation between the FID data and the reference data, and then the RFI and noise were suppressed by setting the corresponding singular values to zero. The validity of the algorithm was verified by processing the measured NMR data. The results indicated that, this method has a significantly suppression of RFI and random noise, and can well preserve the FID signal. At present, the major limitation of the proposed SVD-based ICNR technique is that the threshold value for interference cancellation needs to be manually selected. Finally, the inversion waveform of the applied alternating magnetic field was given by fitting the processed experimental data. PMID:26959024

  16. Real-time measurement of protein adsorption on electrophoretically deposited hydroxyapatite coatings and magnetron sputtered metallic films using the surface acoustic wave technique.

    PubMed

    Meininger, M; Schmitz, T; Wagner, T; Ewald, A; Gbureck, U; Groll, J; Moseke, C

    2016-04-01

    Surface acoustic wave (SAW) biosensors are highly sensitive for mass binding and are therefore used to detect protein-protein and protein-antibody interactions. Whilst the standard surface of the chips is a thin gold film, measurements on implant- or bone-like surfaces could significantly enhance the range of possible applications for this technique. The aim of this study was to establish methods to coat biosensor chips with Ti, TiN, and silver-doped TiN using physical vapor deposition as well as with hydroxyapatite by electrophoresis. To demonstrate that protein adsorption can be detected on these surfaces, binding experiments with fibronectin and fibronectin-specific antibodies have been performed with the coatings, which successfully proved the applicability of PVD and EPD for SAW biosensor functionalization. PMID:26838860

  17. Charge carrier effective mass and concentration derived from combination of Seebeck coefficient and Te125 NMR measurements in complex tellurides

    DOE PAGESBeta

    Levin, E. M.

    2016-06-27

    Thermoelectric materials utilize the Seebeck effect to convert heat to electrical energy. The Seebeck coefficient (thermopower), S, depends on the free (mobile) carrier concentration, n, and effective mass, m*, as S ~ m*/n2/3. The carrier concentration in tellurides can be derived from 125Te nuclear magnetic resonance (NMR) spin-lattice relaxation measurements. The NMR spin-lattice relaxation rate, 1/T1, depends on both n and m* as 1/T1~(m*)3/2n (within classical Maxwell-Boltzmann statistics) or as 1/T1~(m*)2n2/3 (within quantum Fermi-Dirac statistics), which challenges the correct determination of the carrier concentration in some materials by NMR. Here it is shown that the combination of the Seebeck coefficientmore » and 125Te NMR spin-lattice relaxation measurements in complex tellurides provides a unique opportunity to derive the carrier effective mass and then to calculate the carrier concentration. This approach was used to study AgxSbxGe50–2xTe50, well-known GeTe-based high-efficiency tellurium-antimony-germanium-silver thermoelectric materials, where the replacement of Ge by [Ag+Sb] results in significant enhancement of the Seebeck coefficient. Thus, values of both m* and n derived using this combination show that the enhancement of thermopower can be attributed primarily to an increase of the carrier effective mass and partially to a decrease of the carrier concentration when the [Ag+Sb] content increases.« less

  18. (77)Se chemical shift tensor of L-selenocystine: experimental NMR measurements and quantum chemical investigations of structural effects.

    PubMed

    Struppe, Jochem; Zhang, Yong; Rozovsky, Sharon

    2015-03-01

    The genetically encoded amino acid selenocysteine and its dimeric form, selenocystine, are both utilized by nature. They are found in active sites of selenoproteins, enzymes that facilitate a diverse range of reactions, including the detoxification of reactive oxygen species and regulation of redox pathways. Due to selenocysteine and selenocystine's specialized biological roles, it is of interest to examine their (77)Se NMR properties and how those can in turn be employed to study biological systems. We report the solid-state (77)Se NMR measurements of the L-selenocystine chemical shift tensor, which provides the first experimental chemical shift tensor information on selenocysteine-containing systems. Quantum chemical calculations of L-selenocystine models were performed to help understand various structural effects on (77)Se L-selenocystine's chemical shift tensor. The effects of protonation state, protein environment, and substituent of selenium-bonded carbon on the isotropic chemical shift were found to be in a range of ca. 10-20 ppm. However, the conformational effect was found to be much larger, spanning ca. 600 ppm for the C-Se-Se-C dihedral angle range of -180° to +180°. Our calculations show that around the minimum energy structure with a C-Se-Se-C dihedral angle of ca. -90°, the energy costs to alter the dihedral angle in the range from -120° to -60° are within only 2.5 kcal/mol. This makes it possible to realize these conformations in a protein or crystal environment. (77)Se NMR was found to be a sensitive probe to such changes and has an isotropic chemical shift range of 272 ± 30 ppm for this energetically favorable conformation range. The energy-minimized structures exhibited calculated isotropic shifts that lay within 3-9% of those reported in previous solution NMR studies. The experimental solid-state NMR isotropic chemical shift is near the lower bound of this calculated range for these readily accessible conformations. These results suggest

  19. 77Se Chemical Shift Tensor of L-selenocystine: Experimental NMR Measurements and Quantum Chemical Investigations of Structural Effects

    PubMed Central

    Struppe, Jochem; Zhang, Yong; Rozovsky, Sharon

    2015-01-01

    The genetically encoded amino acid selenocysteine and its dimeric form, selenocystine, are both utilized by nature. They are found in active sites of selenoproteins, enzymes that facilitate a diverse range of reactions, including the detoxification of reactive oxygen species and regulation of redox pathways. Due to selenocysteine and selenocystine’s specialized biological roles, it is of interest to examine their 77Se NMR properties and how those can in turn be employed to study biological systems. We report the solid-state 77Se NMR measurements of the L-selenocystine chemical shift tensor, which provides the first experimental chemical shift tensor information of selenocysteine-containing systems. Quantum chemical calculations of L-selenocystine models were performed to help understand various structural effects on 77Se L-selenocystine’s chemical shift tensor. The effects of protonation state, protein environment, and substituent of selenium-bonded carbon on the isotropic chemical shift were found to be in a range of ca. 10–20 ppm. However, the conformational effect was found to be much larger, spanning ca. 600 ppm for the C-Se-Se-C dihedral angle range of −180° to +180°. Our calculations show that around the minimum energy structure with a C-Se-Se-C dihedral angle of ca. −90°, the energy costs to alter the dihedral angle in the range from −120° to −60° are within only 2.5 kcal/mol. This makes it possible to realize these conformations in a protein or crystal environment. 77Se NMR was found to be a sensitive probe to such changes and has an isotropic chemical shift range of 272±30 ppm for this energetically favorable conformation range. The energy-minimized structures exhibited calculated isotropic shifts that lay within 3–9% of those reported in previous solution NMR studies. The experimental solid-state NMR isotropic chemical shift is near the lower bound of this calculated range for these readily accessible conformations. These results

  20. Two-dimensional NMR measurement and point dipole model prediction of paramagnetic shift tensors in solids

    SciTech Connect

    Walder, Brennan J.; Davis, Michael C.; Grandinetti, Philip J.; Dey, Krishna K.; Baltisberger, Jay H.

    2015-01-07

    A new two-dimensional Nuclear Magnetic Resonance (NMR) experiment to separate and correlate the first-order quadrupolar and chemical/paramagnetic shift interactions is described. This experiment, which we call the shifting-d echo experiment, allows a more precise determination of tensor principal components values and their relative orientation. It is designed using the recently introduced symmetry pathway concept. A comparison of the shifting-d experiment with earlier proposed methods is presented and experimentally illustrated in the case of {sup 2}H (I = 1) paramagnetic shift and quadrupolar tensors of CuCl{sub 2}⋅2D{sub 2}O. The benefits of the shifting-d echo experiment over other methods are a factor of two improvement in sensitivity and the suppression of major artifacts. From the 2D lineshape analysis of the shifting-d spectrum, the {sup 2}H quadrupolar coupling parameters are 〈C{sub q}〉 = 118.1 kHz and 〈η{sub q}〉 = 0.88, and the {sup 2}H paramagnetic shift tensor anisotropy parameters are 〈ζ{sub P}〉 = − 152.5 ppm and 〈η{sub P}〉 = 0.91. The orientation of the quadrupolar coupling principal axis system (PAS) relative to the paramagnetic shift anisotropy principal axis system is given by (α,β,γ)=((π)/2 ,(π)/2 ,0). Using a simple ligand hopping model, the tensor parameters in the absence of exchange are estimated. On the basis of this analysis, the instantaneous principal components and orientation of the quadrupolar coupling are found to be in excellent agreement with previous measurements. A new point dipole model for predicting the paramagnetic shift tensor is proposed yielding significantly better agreement than previously used models. In the new model, the dipoles are displaced from nuclei at positions associated with high electron density in the singly occupied molecular orbital predicted from ligand field theory.

  1. Moving NMR

    NASA Astrophysics Data System (ADS)

    Blümich, Bernhard; Casanova, Federico; Danieli, Ernesto; Gong, Qingxia; Greferath, Marcus; Haber, Agnes; Kolz, Jürgen; Perlo, Juan

    2008-12-01

    Initiated by the use of NMR for well logging, portable NMR instruments are being developed for a variety of novel applications in materials testing and process analysis and control. Open sensors enable non-destructive testing of large objects, and small, cup-size magnets become available for high throughput analysis by NMR relaxation and spectroscopy. Some recent developments of mobile NMR are reviewed which delineate the direction into which portable NMR is moving.

  2. Aggregation properties and structural studies of anticancer drug Irinotecan in DMSO solution based on NMR measurements

    NASA Astrophysics Data System (ADS)

    D'Amelio, N.; Aroulmoji, V.; Toraldo, A.; Sundaraganesan, N.; Anbarasan, P. M.

    2012-04-01

    Irinotecan is an antitumor drug mostly used in the treatment of colorectal cancer. Its efficacy is influenced by the chemical state of the molecule undergoing chemical equilibria, metabolic changes and photodegradation. In this work, we describe the chemical equilibria of the drug in dimethyl sulfoxide (DMSO). The energetic barrier for hindered rotation around the bond connecting the piperidino—piperidino moiety with the camptothecin-like fragment was evaluated. Furthermore, we showed how the molecule aggregates in DMSO solution forming dimeric species able to prevent its degradation. The equilibrium constant for self-aggregation was determined by NMR based on the assumption of the isodesmic model. The formation of a dimer was highlighted by NMR diffusion ordered spectroscopy (NMR-DOSY) experiments at the concentrations used. Structural features of the complex were inferred by NOE and 13C chemical shift data. Molecular modelling of the complex driven by experimental data, lead to a structure implying the formation of two hydrogen bonds involving the lactone ring whose opening is one of the main causes of drug degradation. This species is probably responsible for the improved stability of the drug at concentrations higher than 1 mM.

  3. A 1H NMR assay for measuring the photostationary States of photoswitchable ligands.

    PubMed

    Banghart, Matthew R; Trauner, Dirk

    2013-01-01

    Incorporation of photoisomerizable chromophores into small molecule ligands represents a general approach for reversibly controlling protein function with light. Illumination at different wavelengths produces photostationary states (PSSs) consisting of different ratios of photoisomers. Thus optimal implementation of photoswitchable ligands requires knowledge of their wavelength sensitivity. Using an azobenzene-based ion channel blocker as an example, this protocol describes a (1)H NMR assay that can be used to precisely determine the isomeric content of photostationary states (PSSs) as a function of illumination wavelength. Samples of the photoswitchable ligand are dissolved in deuterated water and analyzed by UV/VIS spectroscopy to identify the range of illumination wavelengths that produce PSSs. The PSSs produced by these wavelengths are quantified using (1)H NMR spectroscopy under continuous irradiation through a monochromator-coupled fiber-optic cable. Because aromatic protons of azobenzene trans and cis isomers exhibit sufficiently different chemical shifts, their relative abundances at each PSS can be readily determined by peak integration. Constant illumination during spectrum acquisition is essential to accurately determine PSSs from molecules that thermally relax on the timescale of minutes or faster. This general protocol can be readily applied to any photoswitch that exhibits distinct (1)H NMR signals in each photoisomeric state. PMID:23494375

  4. Tortuosity measurement and the effects of finite pulse widths on xenon gas diffusion NMR studies of porous media.

    PubMed

    Mair, R W; Hürlimann, M D; Sen, P N; Schwartz, L M; Patz, S; Walsworth, R L

    2001-01-01

    We have extended the utility of NMR as a technique to probe porous media structure over length scales of approximately 100-2000 microm by using the spin 1/2 noble gas 129Xe imbibed into the system's pore space. Such length scales are much greater than can be probed with NMR diffusion studies of water-saturated porous media. We utilized Pulsed Gradient Spin Echo NMR measurements of the time-dependent diffusion coefficient, D(t), of the xenon gas filling the pore space to study further the measurements of both the pore surface-area-to-volume ratio, S/V(p), and the tortuosity (pore connectivity) of the medium. In uniform-size glass bead packs, we observed D(t) decreasing with increasing t, reaching an observed asymptote of approximately 0.62-0.65D(0), that could be measured over diffusion distances extending over multiple bead diameters. Measurements of D(t)/D(0) at differing gas pressures showed this tortuosity limit was not affected by changing the characteristic diffusion length of the spins during the diffusion encoding gradient pulse. This was not the case at the short time limit, where D(t)/D(0) was noticeably affected by the gas pressure in the sample. Increasing the gas pressure, and hence reducing D(0) and the diffusion during the gradient pulse served to reduce the previously observed deviation of D(t)/D(0) from the S/V(p) relation. The Pade approximation is used to interpolate between the long and short time limits in D(t). While the short time D(t) points lay above the interpolation line in the case of small beads, due to diffusion during the gradient pulse on the order of the pore size, it was also noted that the experimental D(t) data fell below the Pade line in the case of large beads, most likely due to finite size effects. PMID:11445310

  5. Tortuosity measurement and the effects of finite pulse widths on xenon gas diffusion NMR studies of porous media

    NASA Technical Reports Server (NTRS)

    Mair, R. W.; Hurlimann, M. D.; Sen, P. N.; Schwartz, L. M.; Patz, S.; Walsworth, R. L.

    2001-01-01

    We have extended the utility of NMR as a technique to probe porous media structure over length scales of approximately 100-2000 microm by using the spin 1/2 noble gas 129Xe imbibed into the system's pore space. Such length scales are much greater than can be probed with NMR diffusion studies of water-saturated porous media. We utilized Pulsed Gradient Spin Echo NMR measurements of the time-dependent diffusion coefficient, D(t), of the xenon gas filling the pore space to study further the measurements of both the pore surface-area-to-volume ratio, S/V(p), and the tortuosity (pore connectivity) of the medium. In uniform-size glass bead packs, we observed D(t) decreasing with increasing t, reaching an observed asymptote of approximately 0.62-0.65D(0), that could be measured over diffusion distances extending over multiple bead diameters. Measurements of D(t)/D(0) at differing gas pressures showed this tortuosity limit was not affected by changing the characteristic diffusion length of the spins during the diffusion encoding gradient pulse. This was not the case at the short time limit, where D(t)/D(0) was noticeably affected by the gas pressure in the sample. Increasing the gas pressure, and hence reducing D(0) and the diffusion during the gradient pulse served to reduce the previously observed deviation of D(t)/D(0) from the S/V(p) relation. The Pade approximation is used to interpolate between the long and short time limits in D(t). While the short time D(t) points lay above the interpolation line in the case of small beads, due to diffusion during the gradient pulse on the order of the pore size, it was also noted that the experimental D(t) data fell below the Pade line in the case of large beads, most likely due to finite size effects.

  6. Measurement of Lipid Accumulation in Chlorella vulgaris via Flow Cytometry and Liquid-State ¹H NMR Spectroscopy for Development of an NMR-Traceable Flow Cytometry Protocol

    PubMed Central

    Bono Jr., Michael S.; Garcia, Ravi D.; Sri-Jayantha, Dylan V.; Ahner, Beth A.; Kirby, Brian J.

    2015-01-01

    In this study, we cultured Chlorella vulgaris cells with a range of lipid contents, induced via nitrogen starvation, and characterized them via flow cytometry, with BODIPY 505/515 as a fluorescent lipid label, and liquid-state 1H NMR spectroscopy. In doing so, we demonstrate the utility of calibrating flow cytometric measurements of algal lipid content using triacylglyceride (TAG, also known as triacylglycerol or triglyceride) content per cell as measured via quantitative 1H NMR. Ensemble-averaged fluorescence of BODIPY-labeled cells was highly correlated with average TAG content per cell measured by bulk NMR, with a linear regression yielding a linear fit with r2 = 0.9974. This correlation compares favorably to previous calibrations of flow cytometry protocols to lipid content measured via extraction, and calibration by NMR avoids the time and complexity that is generally required for lipid quantitation via extraction. Flow cytometry calibrated to a direct measurement of TAG content can be used to investigate the distribution of lipid contents for cells within a culture. Our flow cytometry measurements showed that Chlorella vulgaris cells subjected to nitrogen limitation exhibited higher mean lipid content but a wider distribution of lipid content that overlapped the relatively narrow distribution of lipid content for replete cells, suggesting that nitrogen limitation induces lipid accumulation in only a subset of cells. Calibration of flow cytometry protocols using direct in situ measurement of TAG content via NMR will facilitate rapid development of more precise flow cytometry protocols, enabling investigation of algal lipid accumulation for development of more productive algal biofuel feedstocks and cultivation protocols. PMID:26267664

  7. Electrophoretic mobilities of erythrocytes in various buffers

    NASA Technical Reports Server (NTRS)

    Plank, L. D.; Kunze, M. E.; Todd, P. W.

    1985-01-01

    The calibration of space flight equipment depends on a source of standard test particles, this test particle of choice is the fixed erythrocyte. Erythrocytes from different species have different electrophoretic mobilities. Electrophoretic mobility depends upon zeta potential, which, in turn depends upon ionic strength. Zeta potential decreases with increasing ionic strength, so cells have high electrophoretic mobility in space electrophoresis buffers than in typical physiological buffers. The electrophoretic mobilities of fixed human, rat, and rabbit erythrocytes in 0.145 M salt and buffers of varying ionic strength, temperature, and composition, to assess the effects of some of the unique combinations used in space buffers were characterized. Several effects were assessed: glycerol or DMSO (dimethylsulfoxide) were considered for use as cryoprotectants. The effect of these substances on erythrocyte electrophoretic mobility was examined. The choice of buffer depended upon cell mobility. Primary experiments with kidney cells established the choice of buffer and cryoprotectant. A nonstandard temperature of EPM in the suitable buffer was determined. A loss of ionic strength control occurs in the course of preparing columns for flight, the effects of small increases in ionic strength over the expected low values need to be evaluated.

  8. Local electromagnetic properties of magnetic pnictides: a comparative study probed by NMR measurements.

    PubMed

    Majumder, M; Ghoshray, K; Ghoshray, A; Pal, A; Awana, V P S

    2013-05-15

    (75)As and (31)P NMR studies are performed in PrCoAsO and NdCoPO respectively. The Knight shift data in PrCoAsO indicate the presence of an antiferromagnetic interaction between the 4f moments along the c axis in the ferromagnetic state of Co 3d moments. We propose a possible spin structure in this system. The (75)As quadrupolar coupling constant, νQ, increases continuously with decrease of temperature and is found to vary linearly with the intrinsic spin susceptibility, K(iso). This indicates the possibility of the presence of a coupling between charge density and spin density fluctuations. Further, the (31)P NMR Knight shift and spin-lattice relaxation rate (1/T1) in the paramagnetic state of NdCoPO indicate that the differences of LaCoPO and NdCoPO from SmCoPO are due to the decrement of the interlayer separation and not due to the moments of the 4f electrons. The nuclear spin-lattice relaxation time (T1) in NdCoPO shows weak anisotropy at 300 K. Using the self-consistent renormalization (SCR) theory of itinerant ferromagnets, it is shown that in the ab plane, the spin fluctuations are three-dimensional ferromagnetic in nature. From SCR theory the important spin-fluctuation parameters (T0, TA, F¯1) are evaluated. The similarities and dissimilarities of the NMR results in As and P based systems with different rare earths are also discussed. PMID:23604391

  9. Self-diffusion measurements by a mobile single-sided NMR sensor with improved magnetic field gradient

    NASA Astrophysics Data System (ADS)

    Rata, D. G.; Casanova, F.; Perlo, J.; Demco, D. E.; Blümich, B.

    2006-06-01

    A simple and fast method of measuring self-diffusion coefficients of protonated systems with a mobile single-sided NMR sensor is discussed. The NMR sensor uses a magnet geometry that generates a highly flat sensitive volume where a strong and highly uniform static magnetic field gradient is defined. Self-diffusion coefficients were measured by Hahn- and stimulated echoes detected in the presence of the uniform magnetic field gradient of the static field. To improve the sensitivity of these experiments, a Carr-Purcell-Meiboom-Gill pulse sequence was applied after the main diffusion-encoding period. By adding the echo train the experimental time was strongly shortened, allowing the measurement of complete diffusion curves in less than 1 min. This method has been tested by measuring the self-diffusion coefficients D of various organic solvents and poly(dimethylsiloxane) samples with different molar masses. Diffusion coefficients were also measured for n-hexane absorbed at saturation in natural rubber with different cross-link densities. The results show a dependence on the concentration that is in good agreement with the theoretical prediction. Moreover, the stimulated-echo sequence was successfully used to measure the diffusion coefficient as a function of the evolution time in systems with restricted diffusion. This type of experiment proves the pore geometry and gives access to the surface-to-volume ratio. It was applied to measure the diffusion of water in sandstones and sheep Achilles tendon. Thanks to the strong static gradient G0, all diffusion coefficients could be measured without having to account for relaxation during the pulse sequence.

  10. The electrophoretic mobility of montmorillonite. Zeta potential and surface conductivity effects.

    PubMed

    Leroy, Philippe; Tournassat, Christophe; Bernard, Olivier; Devau, Nicolas; Azaroual, Mohamed

    2015-08-01

    Clay minerals have remarkable adsorption properties because of their high specific surface area and surface charge density, which give rise to high electrochemical properties. These electrochemical properties cannot be directly measured, and models must be developed to estimate the electrostatic potential at the vicinity of clay mineral surfaces. In this context, an important model prediction is the zeta potential, which is thought to be representative of the electrostatic potential at the plane of shear. The zeta potential is usually deduced from electrophoretic measurements but for clay minerals, high surface conductivity decreases their mobility, thereby impeding straightforward interpretation of these measurements. By combining a surface complexation, conductivity and electrophoretic mobility model, we were able to reconcile zeta potential predictions with electrophoretic measurements on montmorillonite immersed in NaCl aqueous solutions. The electrochemical properties of the Stern and diffuse layers of the basal surfaces were computed by a triple-layer model. Computed zeta potentials have considerably higher amplitudes than measured zeta potentials calculated with the Smoluchowski equation. Our model successfully reproduced measured electrophoretic mobilities. This confirmed our assumptions that surface conductivity may be responsible for montmorillonite's low electrophoretic mobility and that the zeta potential may be located at the beginning of the diffuse layer. PMID:25875489

  11. Noninvasive estimation of oxygen consumption in human calf muscle through combined NMR measurements of ASL perfusion and T₂ oxymetry.

    PubMed

    Decorte, Nicolas; Buehler, Tania; Caldas de Almeida Araujo, Ericky; Vignaud, Alexandre; Carlier, Pierre G

    2014-01-01

    The objective of this work was to demonstrate the feasibility of measuring muscle O2 consumption (V˙O2) noninvasively with a combination of functional nuclear magnetic resonance (NMR) imaging methods, and to verify that changes in muscle V˙O2 can be detected with a temporal resolution compatible with physiological investigation and patient ease. T2-based oxymetry of arterial and venous blood was combined with the arterial-spin labeling (ASL)-based determination of muscle perfusion. These measurements were performed on 8 healthy volunteers under normoxic and hypoxic conditions in order to assess the sensitivity of measurements over a range of saturation values. Blood samples were drawn simultaneously and used to titrate blood T2 measurements versus hemoglobin O2 saturation (%HbO2) in vitro. The in vitro calibration curve of blood T2 fitted very well with the %HbO2 (r(2): 0.95). The in vivo venous T2 measurements agreed well with the in vitro measurements (intraclass correlation coefficient 0.82, 95% confidence interval 0.61-0.91). Oxygen extraction at rest decreased in the calf muscles subjected to hypoxia (p = 0.031). The combination of unaltered muscle perfusion and pinched arteriovenous O2 difference (p = 0.038) pointed towards a reduced calf muscle V˙O2 during transient hypoxia (p = 0.018). The results of this pilot study confirmed that muscle O2 extraction and V˙O2 can be estimated noninvasively using a combination of functional NMR techniques. Further studies are needed to confirm the usefulness in a larger sample of volunteers and patients. PMID:25531648

  12. Revisiting spin-lattice relaxation time measurements for dilute spins in high-resolution solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Fu, Riqiang; Li, Jun; Cui, Jingyu; Peng, Xinhua

    2016-07-01

    Numerous nuclear magnetic resonance (NMR) measurements of spin-lattice relaxation times (T1S) for dilute spins such as 13C have led to investigations of the motional dynamics of individual functional groups in solid materials. In this work, we revisit the Solomon equations and analyze how the heteronuclear cross relaxation between the dilute S (e.g. 13C) and abundant I (e.g. 1H) spins affects the measured T1S values in solid-state NMR in the absence of 1H saturation during the recovery time. It is found theoretically that at the beginning of the S spin magnetization recovery, the existence of non-equilibrium I magnetization introduces the heteronuclear cross relaxation effect onto the recovery of the S spin magnetization and confirmed experimentally that such a heteronuclear cross relaxation effect results in the recovery overshoot phenomena for the dilute spins when T1S is on the same order of T1H, leading to inaccurate measurements of the T1S values. Even when T1S is ten times larger than T1H, the heteronuclear cross relaxation effect on the measured T1S values is still noticeable. Furthermore, this cross relaxation effect on recovery trajectory of the S spins can be manipulated and even suppressed by preparing the initial I and S magnetization, so as to obtain the accurate T1S values. A sample of natural abundance L-isoleucine powder has been used to demonstrate the T1S measurements and their corresponding measured T1C values under various experimental conditions.

  13. Revisiting spin-lattice relaxation time measurements for dilute spins in high-resolution solid-state NMR spectroscopy.

    PubMed

    Fu, Riqiang; Li, Jun; Cui, Jingyu; Peng, Xinhua

    2016-07-01

    Numerous nuclear magnetic resonance (NMR) measurements of spin-lattice relaxation times (T1S) for dilute spins such as (13)C have led to investigations of the motional dynamics of individual functional groups in solid materials. In this work, we revisit the Solomon equations and analyze how the heteronuclear cross relaxation between the dilute S (e.g. (13)C) and abundant I (e.g. (1)H) spins affects the measured T1S values in solid-state NMR in the absence of (1)H saturation during the recovery time. It is found theoretically that at the beginning of the S spin magnetization recovery, the existence of non-equilibrium I magnetization introduces the heteronuclear cross relaxation effect onto the recovery of the S spin magnetization and confirmed experimentally that such a heteronuclear cross relaxation effect results in the recovery overshoot phenomena for the dilute spins when T1S is on the same order of T1H, leading to inaccurate measurements of the T1S values. Even when T1S is ten times larger than T1H, the heteronuclear cross relaxation effect on the measured T1S values is still noticeable. Furthermore, this cross relaxation effect on recovery trajectory of the S spins can be manipulated and even suppressed by preparing the initial I and S magnetization, so as to obtain the accurate T1S values. A sample of natural abundance l-isoleucine powder has been used to demonstrate the T1S measurements and their corresponding measured T1C values under various experimental conditions. PMID:27187211

  14. Synergy between NMR measurements and MD simulations of protein/RNA complexes: application to the RRMs, the most common RNA recognition motifs.

    PubMed

    Krepl, Miroslav; Cléry, Antoine; Blatter, Markus; Allain, Frederic H T; Sponer, Jiri

    2016-07-27

    RNA recognition motif (RRM) proteins represent an abundant class of proteins playing key roles in RNA biology. We present a joint atomistic molecular dynamics (MD) and experimental study of two RRM-containing proteins bound with their single-stranded target RNAs, namely the Fox-1 and SRSF1 complexes. The simulations are used in conjunction with NMR spectroscopy to interpret and expand the available structural data. We accumulate more than 50 μs of simulations and show that the MD method is robust enough to reliably describe the structural dynamics of the RRM-RNA complexes. The simulations predict unanticipated specific participation of Arg142 at the protein-RNA interface of the SRFS1 complex, which is subsequently confirmed by NMR and ITC measurements. Several segments of the protein-RNA interface may involve competition between dynamical local substates rather than firmly formed interactions, which is indirectly consistent with the primary NMR data. We demonstrate that the simulations can be used to interpret the NMR atomistic models and can provide qualified predictions. Finally, we propose a protocol for 'MD-adapted structure ensemble' as a way to integrate the simulation predictions and expand upon the deposited NMR structures. Unbiased μs-scale atomistic MD could become a technique routinely complementing the NMR measurements of protein-RNA complexes. PMID:27193998

  15. Pulsed NMR Measurements in Superfluid 3He in Aerogel of 97.5 % Porosity

    SciTech Connect

    Ishikawa, Osamu; Kado, Ryusuke; Obara, Ken; Yano, Hideo; Hata, Tohru; Nakagawa, Hisashi; Yokogawa, Hiroshi; Yokoyama, Masaru

    2006-09-07

    Aerogel is made of thin SiO2 strands of a few nanometer diameter. Since the coherence length of superfluid 3He is much longer than the silica strand diameter and is nearly the same as the mean distance between silica strands, aerogel gives us a chance to study the effects of an impurity in superfluid 3He. To investigate what superfluid states are formed in aerogel, we performed a pulsed NMR experiment. Both the A-like and B-like phases show a tipping angle dependent frequency shift in the FID signal after an rf pulse. The dependence in the A-like phase is well explained by an expectation based on the ''robust phase'' introduced by Fomin, while the FID frequencies in the B-like phase behave similarly to those observed in the bulk B phase in a slab geometry with the initial condition of a non-Leggett configuration.

  16. Analyses of gonococcal H8 antigen. Surface location, inter- and intrastrain electrophoretic heterogeneity, and unusual two-dimensional electrophoretic characteristics.

    PubMed

    Hitchcock, P J; Hayes, S F; Mayer, L W; Shafer, W M; Tessier, S L

    1985-12-01

    -dimensional migration characteristics (as measured by antigenicity) were completely destroyed by proteinase K digestion. Activity of H8 polyclonal antibodies to the antigens in two-dimensional gels was completely removed by adsorption of formalin-fixed whole cells, but was not affected by adsorption with LPS. These electrophoretic characteristics may reflect the close association of some nonprotein constituent, perhaps lipid or carbohydrate or both. PMID:2415662

  17. Electron Correlations in Superconductor Rh17S15 Studied by 103Rh NMR and Specific Heat Measurements

    NASA Astrophysics Data System (ADS)

    Koyama, Takehide; Kanda, Keiji; Motoyama, Gaku; Mito, Takeshi; Ueda, Ko-ichi; Kohara, Takao; Nakamura, Hiroyuki; Harima, Hisatomo

    2010-11-01

    The electronic state of superconductor Rh17S15 has been investigated by 103Rh nuclear magnetic resonance (NMR) and specific heat measurements. We have identified the observed NMR lines corresponding to four inequivalent Rh sites in the cubic unit cell and obtained the site-selective information of each site. The spin-lattice relaxation rate 1/T1 indicates that the 4d electrons from the Rh 24m site are the most responsible for the large electronic specific heat coefficient γ. This conclusion is supported by the energy band calculation. Considering the experimental results and the band calculation, we concluded that the γ value is enhanced because of the electron correlations of Rh 4d bands. In the superconducting state, an exponential decrease of both 1/T1 and the electron specific heat are observed, revealing the isotropic superconducting gap with 2Δ/kBTc=4.0. In addition, the decrease of the spin part of the Knight shift indicates the spin-singlet Cooper pair formation. These results demonstrate that Rh17S15 is an s-wave superconductor with enhanced effective electron mass.

  18. Electrophoretic transport equations - Electrophoretic models based on migration only and their interrelationships

    NASA Technical Reports Server (NTRS)

    Thormann, Wolfgang; Mosher, Richard A.

    1985-01-01

    The general equations which describe the electrophoretic transport of components in solution are restated using Newman's general concept of mobilities. A concise derivation of the moving boundary equation and the regulating function from the continuity equation is presented. Various other regulating principles across moving and stationary boundaries are also discussed, which permits a review of the features and interrelationships of the electrophoretic models based on electromigration only. The effect of considering an interactive (dissociating) solvent on the mathematical treatment is discussed.

  19. NMR logging apparatus

    DOEpatents

    Walsh, David O; Turner, Peter

    2014-05-27

    Technologies including NMR logging apparatus and methods are disclosed. Example NMR logging apparatus may include surface instrumentation and one or more downhole probes configured to fit within an earth borehole. The surface instrumentation may comprise a power amplifier, which may be coupled to the downhole probes via one or more transmission lines, and a controller configured to cause the power amplifier to generate a NMR activating pulse or sequence of pulses. Impedance matching means may be configured to match an output impedance of the power amplifier through a transmission line to a load impedance of a downhole probe. Methods may include deploying the various elements of disclosed NMR logging apparatus and using the apparatus to perform NMR measurements.

  20. Protein electrophoretic migration data from custom and commercial gradient gels.

    PubMed

    Miller, Andrew J; Roman, Brandon; Norstrom, Eric M

    2016-12-01

    This paper presents data related to the article "A method for easily customizable gradient gel electrophoresis" (A.J. Miller, B. Roman, E.M. Norstrom, 2016) [1]. Data is presented on the rate of electrophoretic migration of proteins in both hand-poured and commercially acquired acrylamide gradient gels. For each gel, migration of 9 polypeptides of various masses was measured upon completion of gel electrophoresis. Data are presented on the migration of proteins within separate lanes of the same gel as well as migration rates from multiple gels. PMID:27622203

  1. Measuring the Longitudinal NMR Relaxation Rates of Fast Relaxing Nuclei Using a Signal Eliminating Relaxation Filter

    NASA Astrophysics Data System (ADS)

    Hansen, D. Flemming; Led, Jens J.

    2001-08-01

    A new experiment for selective determination of the relaxation rates of fast relaxing NMR signals is presented. The experiment is derived from the conventional inversion recovery experiment by substituting the 180° inversion pulse of this experiment with a signal eliminating relaxation filter (SERF) consisting of three 180° pulses separated by two variable delays, Δ1 and Δ2. The SERF experiment allows a selective suppression of signals with relaxation rates below a given limit while monitoring the relaxation of faster relaxing signals. The experiment was tested on a sample of 20% oxidized plastocyanin from Anabaena variabilis, where the fast exchange of an electron between the reduced (diamagnetic) and the oxidized (paramagnetic) form results in a series of average signals with widely different relaxation rates. To ensure an optimum extraction of information from the experimental data, the relaxation rates were obtained from the SERF experiment by a simultaneous analysis of all the FIDs of the experiment using a fast linear prediction model method developed previously. The reliability of the relaxation rates obtained from the SERF experiment was confirmed by a comparison of the rates with the corresponding rates obtained from a conventional inversion recovery experiment.

  2. Enhancement of electrophoretic mobility of microparticles near a solid wall--experimental verification.

    PubMed

    Liang, Qian; Zhao, Cunlu; Yang, Chun

    2015-03-01

    Although the existing theories have predicted enhancement of electrophoretic mobility of microparticles near a solid wall, the relevant experimental studies are rare. This is mainly due to difficulties in experimentally controlling and measuring particle-wall separations under dynamic electrophoretic conditions. This paper reports an experimental verification of the enhancement of electrophoretic mobility of a microparticle moving near the wall of a microchannel. This is achieved by balancing dielectrophoretic and lift forces against gravitational force acting on the microparticle so as to control the gap of particle-wall separation. A simple experimental setup is configured and a fabrication method is developed to measure such separation gap. The experiments are conducted for various particle sizes under different electric field strengths. Our experimental results are compared against the available theoretical predictions in the literature. PMID:25421107

  3. Phosphorus-31 NMR magnetization transfer measurements of metabolic reaction rates in the rat heart and kidney in vivo

    SciTech Connect

    Koretsky, A.P.

    1984-01-01

    /sup 31/P NMR is a unique tool to study bioenergetics in living cells. The application of magnetization transfer techniques to the measurement of steady-state enzyme reaction rates provides a new approach to understanding the regulation of high energy phosphate metabolism. This dissertation is concerned with the measurement of the rates of ATP synthesis in the rat kidney and of the creatine kinase catalyzed reaction in the rat heart in situ. The theoretical considerations of applying magnetization transfer techniques to intact organs are discussed with emphasis on the problems associated with multiple exchange reactions and compartmentation of reactants. Experimental measurements of the ATP synthesis rate were compared to whole kidney oxygen consumption and Na/sup +/ reabsorption rates to derive ATP/O values. The problems associated with ATP synthesis rate measurements in kidney, e.g. the heterogeneity of the inorganic phosphate resonance, are discussed and experiments to overcome these problems proposed. In heart, the forward rate through creatine kinase was measured to be larger than the reverse rate. To account for the difference in forward and reverse rates a model is proposed based on the compartmentation of a small pool of ATP.

  4. Reduction of magnetic field fluctuations in powered magnets for NMR using inductive measurements and sampled-data feedback control.

    PubMed

    Li, Mingzhou; Schiano, Jeffrey L; Samra, Jenna E; Shetty, Kiran K; Brey, William W

    2011-10-01

    Resistive and hybrid (resistive/superconducting) magnets provide substantially higher magnetic fields than those available in low-temperature superconducting magnets, but their relatively low spatial homogeneity and temporal field fluctuations are unacceptable for high resolution NMR. While several techniques for reducing temporal fluctuations have demonstrated varying degrees of success, this paper restricts attention to methods that utilize inductive measurements and feedback control to actively cancel the temporal fluctuations. In comparison to earlier studies using analog proportional control, this paper shows that shaping the controller frequency response results in significantly higher reductions in temporal fluctuations. Measurements of temporal fluctuation spectra and the frequency response of the instrumentation that cancels the temporal fluctuations guide the controller design. In particular, we describe a sampled-data phase-lead-lag controller that utilizes the internal model principle to selectively attenuate magnetic field fluctuations caused by the power supply ripple. We present a quantitative comparison of the attenuation in temporal fluctuations afforded by the new design and a proportional control design. Metrics for comparison include measurements of the temporal fluctuations using Faraday induction and observations of the effect that the fluctuations have on nuclear resonance measurements. PMID:21885308

  5. New reflective-type electrophoretic display

    NASA Astrophysics Data System (ADS)

    Orsaev, A. M.; Orsaev, T. M.; Gaev, D. S.

    2001-06-01

    Advantages and problems of the electrophoretic display design are considered. To increase its lifetime a new EPD version is proposed, and operation process is described. Main distinguish feature is the present of an agile film as the third electrode. Such a display can be manufactured on the base of standard technological processes and promises to be X-Y multiplex addressed, simple and cheap for manufacturing.

  6. Solubilization of amphiphilic carboxylic acids in nonionic micelles: determination of partition coefficients from pKa measurements and NMR experiments.

    PubMed

    Dupont-Leclercq, Laurence; Giroux, Sébastien; Henry, Bernard; Rubini, Patrice

    2007-10-01

    The solubilization of octylamidotartaric acid (C8T) and octanoic acid (C8C) in Triton X-100 and Brij 58 nonionic micelles has been studied by pHmetric and 1H NMR self-diffusion experiments. As both C8C and C8T exhibit acid-base properties, a distinction between the partition of the neutral acidic form, in terms of the partition coefficient KPH, and the partition of the charged basic form, in terms of the partition coefficient KP-, has been made. The acidity constants, Ka, of C8T and C8C in the presence of micelles have been evaluated from pHmetric experiments. For both solutes, an increase in the pKa is observed in micellar media due to the difference in the partition of acidic and basic forms of the solutes. A model has been developed to determine KPH and KP- from the pKa shifts observed. The values obtained by this pKa shift modeling method and those from self-diffusion coefficient measurements are in good agreement. The acidic form of C8C is incorporated to a larger extent into the Brij 58 micelles than the acidic form of C8T, whereas the opposite trend is observed for the basic forms. Both the acidic and basic forms of C8T are more easily incorporated into Brij 58 micelles than into Triton X-100 micelles. The influence of the structure of the polar head on the solubilization properties is demonstrated. Moreover, evidence for the localization of the solutes in the micelles is obtained from the comparison of the partition coefficients and from 1H NMR data. PMID:17850105

  7. Non-invasive measurement of brain glycogen by NMR spectroscopy and its application to the study of brain metabolism

    PubMed Central

    Tesfaye, Nolawit; Seaquist, Elizabeth R.; Öz, Gülin

    2011-01-01

    Glycogen is the reservoir for glucose in the brain. Beyond the general agreement that glycogen serves as an energy source in the central nervous system, its exact role in brain energy metabolism has yet to be elucidated. Experiments performed in cell and tissue culture and animals have shown that glycogen content is affected by several factors including glucose, insulin, neurotransmitters, and neuronal activation. The study of in vivo glycogen metabolism has been hindered by the inability to measure glycogen non-invasively, but in the past several years, the development of a non-invasive localized 13C nuclear magnetic resonance (NMR) spectroscopy method has enabled the study of glycogen metabolism in the conscious human. With this technique, 13C-glucose is administered intravenously and its incorporation into and wash-out from brain glycogen is tracked. One application of this method has been to the study of brain glycogen metabolism in humans during hypoglycemia: data have shown that mobilization of brain glycogen is augmented during hypoglycemia and, after a single episode of hypoglycemia, glycogen synthesis rate is increased, suggesting that glycogen stores rebound to levels greater than baseline. Such studies suggest glycogen may serve as a potential energy reservoir in hypoglycemia and may participate in the brain's adaptation to recurrent hypoglycemia and eventual development of hypoglycemia unawareness. Beyond this focused area of study, 13C NMR spectroscopy has a broad potential for application in the study of brain glycogen metabolism and carries the promise of a better understanding of the role of brain glycogen in diabetes and other conditions. PMID:21732401

  8. Electrophoretic mobilities of neutral analytes and electroosmotic flow markers in aqueous solutions of Hofmeister salts.

    PubMed

    Křížek, Tomáš; Kubíčková, Anna; Hladílková, Jana; Coufal, Pavel; Heyda, Jan; Jungwirth, Pavel

    2014-03-01

    Small neutral organic compounds have traditionally the role of EOF markers in electrophoresis, as they are expected to have zero electrophoretic mobility in external electric fields. The BGE contains, however, ions that have unequal affinities to the neutral molecules, which in turn results in their mobilization. In this study we focused on two EOF markers-thiourea and DMSO, as well as on N-methyl acetamide (NMA) as a model of the peptide bond. By means of CE and all atom molecular dynamics simulations we explored mobilization of these neutral compounds in large set of Hofmeister salts. Employing a statistical mechanics approach, we were able to reproduce by simulations the experimental electrophoretic mobility coefficients. We also established the role of the chemical composition of marker and the BGE on the measured electrophoretic mobility coefficient. For NMA, we interpreted the results in terms of the relative affinities of cations versus anions to the peptide bond. PMID:24338984

  9. Local electronic state in the half-metallic ferromagnet CrO2 investigated by site-selective 53Cr NMR measurements

    NASA Astrophysics Data System (ADS)

    Takeda, Hikaru; Shimizu, Yasuhiro; Kobayashi, Yoshiaki; Itoh, Masayuki; Jin-no, Takaaki; Isobe, Masahiko; Ueda, Yutaka; Yoshida, Sho; Muraoka, Yuji; Yokoya, Takayoshi

    2016-06-01

    We have made 53Cr NMR measurements on polycrystalline and single-crystalline film samples to study the local electronic state of a half-metallic ferromagnet CrO2 which has the rutile structure with one crystallographically equivalent Cr site. We observe two kinds of 53Cr NMR spectra in the ferromagnetic state of both the samples. An analysis on the hyperfine field shows the presence of two Cr sites with different orbital occupancies, suggesting that a local orbital order takes place with breaking the local symmetry in the rutile structure. This may be ascribed to the negative charge transfer between chromium and oxygen ions.

  10. Variable temperature system using vortex tube cooling and fiber optic temperature measurement for low temperature magic angle spinning NMR.

    PubMed

    Martin, Rachel W; Zilm, Kurt W

    2004-06-01

    We describe the construction and operation of a variable temperature (VT) system for a high field fast magic angle spinning (MAS) probe. The probe is used in NMR investigations of biological macromolecules, where stable setting and continuous measurement of the temperature over periods of several days are required in order to prevent sample overheating and degradation. The VT system described is used at and below room temperature. A vortex tube is used to provide cooling in the temperature range of -20 to 20 degrees C, while a liquid nitrogen-cooled heat exchanger is used below -20 degrees C. Using this arrangement, the lowest temperature that is practically achievable is -140 degrees C. Measurement of the air temperature near the spinning rotor is accomplished using a fiber optic thermometer that utilizes the temperature dependence of the absorption edge of GaAs. The absorption edge of GaAs also has a magnetic field dependence that we have measured and corrected for. This dependence was calibrated at several field strengths using the well-known temperature dependence of the (1)H chemical shift difference of the protons in methanol. PMID:15140428

  11. NMR-Based Amide Hydrogen-Deuterium Exchange Measurements for Complex Membrane Proteins: Development and Critical Evaluation

    NASA Astrophysics Data System (ADS)

    Czerski, Lech; Vinogradova, Olga; Sanders, Charles R.

    2000-01-01

    A method for measuring site-specific amide hydrogen-deuterium exchange rates for membrane proteins in bilayers is reported and evaluated. This method represents an adaptation and extension of the approach of Dempsey and co-workers (Biophys. J. 70, 1777-1788 (1996)) and is based on reconstituting 15N-labeled membrane proteins into phospholipid bilayers, followed by lyophilization and rehydration with D2O or H2O (control). Following incubation for a time t under hydrated conditions, samples are again lyophilized and then solubilized in an organic solvent system, where 1H-15N HSQC spectra are recorded. Comparison of spectra from D2O-exposed samples to spectra from control samples yields the extent of the H-D exchange which occurred in the bilayers during time t. Measurements are site specific if specific 15N labeling is used. The first part of this paper deals with the search for a suitable solvent system in which to solubilize complex membrane proteins in an amide "exchange-trapped" form for NMR quantitation of amide peak intensities. The second portion of the paper documents application of the overall procedure to measuring site-specific amide exchange rates in diacylglycerol kinase, a representative integral membrane protein. Both the potential usefulness and the significant limitations of the new method are documented.

  12. Luminescent electrophoretic particles via miniemulsion polymerization for night-vision electrophoretic displays.

    PubMed

    Meng, Xianwei; Wen, Ting; Qiang, Li; Ren, Jun; Tang, Fangqiong

    2013-05-01

    A novel glowing electrophoretic display (EPD) is achieved by luminescent electrophoretic particles (EPs), which is potentially to improve the situation in which the existing EPDs disable in darkness. To combine both modes of reflective and emissive displays, a trilayer luminescence EP is designed and synthesized via an improved miniemulsion polymerization. The luminescence EP is composed of a pigment core, a polystyrene interlayer, and a fluorescent coating. The particle sizes are from 140 to 170 nm, and the size distribution is narrow. Their ζ potential value is -12.4 mV, which is enough to migrate in the electrophoretic fluid by the driving of an electric field. The display performance of the particles in an EPD cell has been characterized under the bias of 20 V. Both the reflectance (491 nm) and fluorescence (521 nm) intensities of the EPD cell remained in a constant range after 30 switches. PMID:23547950

  13. Electrophoretic mobility of spherical particles in bounded domain.

    PubMed

    Liu, Yu-Wei; Pennathur, Sumita; Meinhart, Carl D

    2016-01-01

    In this study, we improve on our 3D steady-state model of electrophoretic motion of spherical particles in bounded fluidic channels (Liu et al., 2014) to include the effect of nonsymmetric electrolytes, and further validate this improved model with detailed comparisons to experimental data. Specifically, we use the experimentally-measured particle mobilities from the work of Semenov et al. (2013), Napoli et al. (2011), and Wynne et al. (2012) to determine the corresponding particle zeta potentials using our model, and compare these results with classical theory. Incorporating the effects of nonsymmetric electrolytes, EDL polarization, and confinement, we show that our improved model is applicable to a wide range of practical experimental conditions, for example, particles that have high zeta potentials in a bounded channel filled with nonsymmetric electrolyte solutions, where classical theory is not applicable. In addition, we find that when electrolyte concentration is comparable to the concentration of hydronium or hydroxide ions, the complicated composition of ions increases the particle mobility. Finally, increased electrophoretic mobility can be observed when buffer solutions (phosphate or borate) were used as electrolyte solutions in experiments as opposed to simple symmetric electrolytes. PMID:26397906

  14. Electrophoretic deposition of composite hydroxyapatite-chitosan coatings

    SciTech Connect

    Pang Xin; Zhitomirsky, Igor . E-mail: zhitom@mcmaster.ca

    2007-04-15

    Cathodic electrophoretic deposition has been utilized for the fabrication of composite hydroxyapatite-chitosan coatings on 316L stainless steel substrates. The addition of chitosan to the hydroxyapatite suspensions promoted the electrophoretic deposition of the hydroxyapatite nanoparticles and resulted in the formation of composite coatings. The obtained coatings were investigated by X-ray diffraction, thermogravimetric and differential thermal analysis, scanning and transmission electron microscopy, potentiodynamic polarization measurements, and electrochemical impedance spectroscopy. It was shown that the deposit composition can be changed by a variation of the chitosan or hydroxyapatite concentration in the solutions. Experimental conditions were developed for the fabrication of hydroxyapatite-chitosan nanocomposites containing 40.9-89.8 wt.% hydroxyapatite. The method enabled the formation of adherent and uniform coatings of thicknesses up to 60 {mu}m. X-ray studies revealed that the preferred orientation of the hydroxyapatite nanoparticles in the chitosan matrix increases with decreasing hydroxyapatite content in the composite coatings. The obtained coatings provided the corrosion protection for the 316L stainless steel substrates00.

  15. Analysis of amorphous solid dispersions using 2D solid-state NMR and (1)H T(1) relaxation measurements.

    PubMed

    Pham, Tran N; Watson, Simon A; Edwards, Andrew J; Chavda, Manisha; Clawson, Jacalyn S; Strohmeier, Mark; Vogt, Frederick G

    2010-10-01

    Solid-state NMR (SSNMR) can provide detailed structural information about amorphous solid dispersions of pharmaceutical small molecules. In this study, the ability of SSNMR experiments based on dipolar correlation, spin diffusion, and relaxation measurements to characterize the structure of solid dispersions is explored. Observation of spin diffusion effects using the 2D (1)H-(13)C cross-polarization heteronuclear correlation (CP-HETCOR) experiment is shown to be a useful probe of association between the amorphous drug and polymer that is capable of directly proving glass solution formation. Dispersions of acetaminophen and indomethacin in different polymers are examined using this approach, as well as (1)H double-quantum correlation experiments to probe additional structural features. (1)H-(19)F CP-HETCOR serves a similar role for fluorinated drug molecules such as diflunisal in dispersions, providing a rapid means to prove the formation of a glass solution. Phase separation is detected using (13)C, (19)F, and (23)Na-detected (1)H T(1) experiments in crystalline and amorphous solid dispersions that contain small domains. (1)H T(1) measurements of amorphous nanosuspensions of trehalose and dextran illustrate the ability of SSNMR to detect domain size effects in dispersions that are not glass solutions via spin diffusion effects. Two previously unreported amorphous solid dispersions involving up to three components and containing voriconazole and telithromycin are analyzed using these experiments to demonstrate the general applicability of the approach. PMID:20681586

  16. Measurement of the intracrystalline self-diffusion of xenon in zeolites by the NMR pulsed field gradient technique

    SciTech Connect

    Heink, W.; Kaerger, J.; Pfeifer, H.; Stallmach, F. )

    1990-03-14

    With use of {sup 129}Xe NMR, the NMR pulsed field gradient technique is applied to study the self-diffusion of xenon adsorbed on zeolites NaX, NaCaA, and ZSM-5. In their dependence on both the type of adsorbent and the sorbate concentration, the self-diffusion coefficients are found to follow the same patterns as previously determined for methane by {sup 1}H NMR. For NaCaA, the comparison of the present results with literature data reveals large discrepancies, while recent computer simulations of xenon self-diffusion in ZSM-5 are found to be in reasonable agreement.

  17. Solid-state Hadamard NMR spectroscopy: Simultaneous measurements of multiple selective homonuclear scalar couplings

    NASA Astrophysics Data System (ADS)

    Kakita, Veera Mohana Rao; Kupče, Eriks; Bharatam, Jagadeesh

    2015-02-01

    Unambiguous measurement of homonuclear scalar couplings (J) in multi-spin scalar network systems is not straightforward. Further, the direct measurement of J-couplings is obscured in solid-state samples due to the dipolar and chemical shift anisotropy (CSA)-dominated line broadening, even under the magic angle spinning (MAS). We present a new multiple frequency selective spin-echo method based on Hadamard matrix encoding, for simultaneous measurement of multiple homonuclear scalar couplings (J) in the solid-state. In contrast to the Hadamard encoded selective excitation schemes known for the solution-state, herein the selectivity is achieved during refocusing period. The Hadamard encoded refocusing scheme concurrently allows to create the spin-spin commutation property between number of spin-pairs of choice in uniformly labelled molecules, which, therefore avoids (1) the repetition of the double selective refocusing experiments for each spin-pair and (2) the synthesis of expensive selective labelled molecules. The experimental scheme is exemplified for determining 1JCC and 3JCC values in 13C6L-Histidine.HCl molecule, which are found to be in excellent agreement with those measured in conventional double frequency selective refocusing mode as well as in the solution-state. This method can be simply extended to 2D/3D pulse schemes and be applied to small bio-molecular solids.

  18. Solid-state Hadamard NMR spectroscopy: simultaneous measurements of multiple selective homonuclear scalar couplings.

    PubMed

    Kakita, Veera Mohana Rao; Kupče, Eriks; Bharatam, Jagadeesh

    2015-02-01

    Unambiguous measurement of homonuclear scalar couplings (J) in multi-spin scalar network systems is not straightforward. Further, the direct measurement of J-couplings is obscured in solid-state samples due to the dipolar and chemical shift anisotropy (CSA)-dominated line broadening, even under the magic angle spinning (MAS). We present a new multiple frequency selective spin-echo method based on Hadamard matrix encoding, for simultaneous measurement of multiple homonuclear scalar couplings (J) in the solid-state. In contrast to the Hadamard encoded selective excitation schemes known for the solution-state, herein the selectivity is achieved during refocusing period. The Hadamard encoded refocusing scheme concurrently allows to create the spin-spin commutation property between number of spin-pairs of choice in uniformly labelled molecules, which, therefore avoids (1) the repetition of the double selective refocusing experiments for each spin-pair and (2) the synthesis of expensive selective labelled molecules. The experimental scheme is exemplified for determining (1)JCC and (3)JCC values in (13)C6l-Histidine.HCl molecule, which are found to be in excellent agreement with those measured in conventional double frequency selective refocusing mode as well as in the solution-state. This method can be simply extended to 2D/3D pulse schemes and be applied to small bio-molecular solids. PMID:25554944

  19. ELECTROPHORETIC MOBILITIES OF ESCHERICHIA COLI 0157:H7 AND WILD-TYPE ESCHERICHIA COLI STRAINS

    EPA Science Inventory

    The electrophoretic mobility (EPM) of a number of human-virulent and "wild-type" Escherichia coli strains in phosphate buffered water was measured. The impact of pH, ionic strength, cation type (valence) and concentration, and bacterial strain on the EPM was investigated. Resul...

  20. Large-Area Chemically Modified Graphene Films: Electrophoretic Deposition and Characterization by Soft X-ray Absorption Spectroscopy

    SciTech Connect

    Lee, V.; Whittaker, L; Jaye, C; Baroudi, K; Fischer, D; Banerjee, S

    2009-01-01

    A facile, rapid, and scalable electrophoretic deposition approach is developed for the fabrication of large-area chemically derived graphene films on conductive substrates based on the electrophoretic deposition of graphene oxide and reduced graphene oxide components. Two distinctive approaches for fabricating conformal graphene films are developed. In the first approach, graphene oxide sheets are electrophoretically deposited from an aqueous solution after the oxidation of graphite to graphite oxide and the subsequent exfoliation of graphite oxide to graphene oxide. Next, the graphene oxide films are reduced via dip-coating in an aqueous solution of hydrazine. In the second approach, graphene oxide is reduced to graphene nanosheets in a strongly alkaline solution and the reduced graphene sheets are directly electrophoretically deposited onto conductive substrates. The film thickness can be modified by the deposition time and the obtained films span several square millimeters in area. Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is used to study the surface chemistry, electronic band structure, and degree of alignment of the electrophoretically deposited films. Polarized NEXAFS measurements verify the presence of epoxide surface functionalities on the graphene basal planes and indicate significant recovery of extended p-bonded networks upon defunctionalization by hydrazine treatment. These measurements further indicate significantly improved alignment of the graphene sheet components of the films parallel to the substrate surface when defunctionalization is performed prior to electrophoretic deposition.

  1. Sizing of reverse micelles in microemulsions using NMR measurements of diffusion.

    PubMed

    Law, Susan J; Britton, Melanie M

    2012-08-14

    This paper reports the size of reverse micelles (RMs) in AOT/octane/H(2)O and CTAB/hexanol/H(2)O microemulsions using magnetic resonance (MR) pulsed field gradient (PFG) measurements of diffusion. Diffusion data were measured using the pulsed gradient stimulated echo (PGSTE) experiment for surfactant molecules residing in the RM interface. Inverse Laplace transformation of these data generated diffusion coefficients for the RMs, which were converted into hydrodynamic radii using the Stokes-Einstein relation. This technique is complementary to those previously used to size RMs, such as dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS), but also offers several advantages, which are discussed. RM sizes, determined using the PGSTE method, in the AOT (sodium bis(2-ethylhexyl) sulfosuccinate) and CTAB (cetyltrimethylammonium bromide) microemulsions were compared with previous DLS and SAXS data, showing good agreement. Methods for determining number distributions from the PGSTE data, through the use of scaling factors, were investigated. PMID:22794150

  2. Measurement of multilamellar onion dimensions under shear using frequency domain pulsed gradient NMR

    NASA Astrophysics Data System (ADS)

    Lutti, Antoine; Callaghan, Paul T.

    2007-08-01

    We present a simple method by which the dimensions of shear-induced multilamellar vesicles (MLVs), also known as onions, can be measured during the shearing process itself. This approach is based on the use of a closely spaced train of magnetic field gradient pulses applied during a CPMG echo sequence. The CPMG train compensates flow effects while the frequency-dependence of apparent diffusion can reveal the onion size. We present here a simple phenomenological model for restricted diffusion in multilamellar vesicles, which may be used to interpret the resulting diffusion spectrum. We demonstrate this approach with MLVs formed from the lamellar phase of sodium dodecyl sulfate (SDS) in water and octanol.

  3. Improvements in in-plane electrophoretic displays

    NASA Astrophysics Data System (ADS)

    Henzen, Alex

    2011-03-01

    Electronic paper is now developing fast into an accepted alternative for paper. Its applications nowadays seem focused on books, documents and newspapers. Development of credible color implementations of electrophoretic displays has been initiated, focusing on multi-layer in-plane electrophoresis, but the difficulties associated with these systems (particle drift, aperture, accuracy) were so far not solved. Electro-osmotic principles lead to openings towards multi-layer color displays as well as fast switching, high reflectance grayscale displays. Drift, aperture and accuracy can be brought to the level necessary to create in-plane switching electro-osmotic displays without the need for encapsulation

  4. Scanning and storage of electrophoretic records

    DOEpatents

    McKean, Ronald A.; Stiegman, Jeff

    1990-01-01

    An electrophoretic record that includes at least one gel separation is mounted for motion laterally of the separation record. A light source is positioned to illuminate at least a portion of the record, and a linear array camera is positioned to have a field of view of the illuminated portion of the record and orthogonal to the direction of record motion. The elements of the linear array are scanned at increments of motion of the record across the field of view to develop a series of signals corresponding to intensity of light at each element at each scan increment.

  5. Macromolecular Crowding Studies of Amino Acids Using NMR Diffusion Measurements and Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Virk, Amninder; Stait-Gardner, Timothy; Willis, Scott; Torres, Allan; Price, William

    2015-02-01

    Molecular crowding occurs when the total concentration of macromolecular species in a solution is so high that a considerable proportion of the volume is physically occupied and therefore not accessible to other molecules. This results in significant changes in the solution properties of the molecules in such systems. Macromolecular crowding is ubiquitous in biological systems due to the generally high intracellular protein concentrations. The major hindrance to understanding crowding is the lack of direct comparison of experimental data with theoretical or simulated data. Self-diffusion is sensitive to changes in the molecular weight and shape of the diffusing species, and the available diffusion space (i.e., diffusive obstruction). Consequently, diffusion measurements are a direct means for probing crowded systems including the self-association of molecules. In this work, nuclear magnetic resonance measurements of the self-diffusion of four amino acids (glycine, alanine, valine and phenylalanine) up to their solubility limit in water were compared directly with molecular dynamics simulations. The experimental data were then analyzed using various models of aggregation and obstruction. Both experimental and simulated data revealed that the diffusion of both water and the amino acids were sensitive to the amino acid concentration. The direct comparison of the simulated and experimental data afforded greater insights into the aggregation and obstruction properties of each amino acid.

  6. Sterically stabilized liposomes. Reduction in electrophoretic mobility but not electrostatic surface potential.

    PubMed Central

    Woodle, M C; Collins, L R; Sponsler, E; Kossovsky, N; Papahadjopoulos, D; Martin, F J

    1992-01-01

    The electrophoretic mobility of liposomes containing a negatively charged derivative of phosphatidylethanolamine with a large headgroup composed of the hydrophilic polymer polyethylene glycol (PEG-PE) was determined by Doppler electrophoretic light scattering. The results show that this method is improved by the use of measurements at multiple angles to eliminate artifacts and that very small mobilities can be measured. The electrophoretic mobility of liposomes with 5 to 10 mol% PEG-PE is approximately -0.5 mu ms-1/Vcm-1 regardless of PEG-PE content compared with approximately -2 mu ms-1/Vcm-1 for similar liposomes but containing 7.5% phosphatidylglycerol (PG) instead of PEG-PE. Measurements of surface potential by distribution of an anionic fluorescent probe show that the PEG-PE imparts a negative charge identical to that by PG, consistent with the expectation of similar locations of the ionized phosphate responsible for the charge. The reduced mobility imparted by the surface bound PEG is attributed to a mechanism similar to that described for colloidal steric stabilization: hydrodynamic drag moves the hydrodynamic plane of shear, or the hydrodynamic radius, away from the charge-bearing plane, that of the phosphate moities. An extended length of approximately 50 A for the 2,000 molecular weight PEG is estimated from the reduction in electrophoretic mobility. PMID:1581503

  7. Proton and carbon NMR measurements of the effects of hydration on the wheat protein ω-gliadin

    NASA Astrophysics Data System (ADS)

    Belton, P. S.; Gil, A. M.; Grant, A.; Alberti, E.; Tatham, A. S.

    1998-07-01

    The wheat protein ω-gliadin consists of a simple repeat sequence composed mainly of proline and glutamine. It thus represents a simple model for many cereal proteins and other proline and glutamine rich sequences which occur in multiple repeats. The behaviour on hydration has been examined by the measurement of proton NMR relaxation times. Sidechain motions (methyl and amino group rotation, proline ring puckering) were largely responsible for T1 relaxation. It was found that the glass transition does not affect T1 and T1 ρ relaxation and only affects transverse relaxation. Magic angle spinning experiments have been used to observe line narrowed proton spectra as well as carbon cross polarisation spectra. In the proton spectra, at high levels of hydration, backbone and sidechain NH groups are observed indicating that whole segments of the protein chain are in the mobile regime. The carbon spectra are characterised by a loss of the proline C δ signal intensity at high levels of hydration indicating the involvement of proline in the hydration process. It is concluded that the behaviour of ω-gliadin on hydration may be explained by the formation of mobile protein loops together with residual regions of strong interprotein interaction.

  8. 19F Magic angle spinning NMR reporter molecules: empirical measures of surface shielding, polarisability and H-bonding.

    PubMed

    Budarin, Vitaliy L; Clark, James H; Deswarte, Fabien E I; Mueller, Karl T; Tavener, Stewart J

    2007-06-14

    Magic Angle Spinning (MAS) (19)F NMR spectra have been obtained and chemical shifts measured for 37 molecules in the gas phase and adsorbed on the surfaces of six common materials: octadecyl- and octyl-functionalised chromatography silicas, Kieselgel 100 silica, Brockmann neutral alumina, Norit activated charcoal and 3-(1-piperidino)propyl functionalised silica. From these six surfaces, octadecyl-silica is selected as a non-polar reference to which the others are compared. The change in chemical shift of a fluorine nucleus within a molecule on adsorption to a surface from the gas phase, Deltadelta(gas)(surface), is described by the empirical relationship: Deltadelta(gas)(surface) = delta(s) + (alpha(s)+pi(s))/alpha(r) (Deltadelta(gas)(reference) - delta(r)) + delta(HBA) + delta(HBD), where delta(s) and delta(r) are constants that describe the chemical shift induced by the electromagnetic field of the surface under investigation and reference surface, alpha(s) and alpha(r) are the relative surface polarisability for the surface and reference, pi(s) is an additional contribution to the surface polarisabilities due to its ability to interact with aromatic molecules, and delta(HBA) and delta(HBD) are measurements of the hydrogen acceptor and donor properties of the surface. These empirical parameters are measured for the surfaces under study. Silica and alumina are found to undergo specific interactions with aromatic reporter molecules and both accept and donate H-bonds. Activated charcoal was found to have an extreme effect on shielding but no specific interactions with the adsorbed molecules. 3-(1-Piperidino)propyl functionalised silica exhibits H-bond acceptor ability, but does not donate H-bonds. PMID:17487325

  9. Autocorrelation spectra of an air-fluidized granular system measured by NMR

    NASA Astrophysics Data System (ADS)

    Lasic, S.; Stepisnik, J.; Mohoric, A.; Sersa, I.; Planinsic, G.

    2006-09-01

    A novel insight into the dynamics of a fluidized granular system is given by a nuclear magnetic resonance method that yields the spin-echo attenuation proportional to the spectrum of the grain positional fluctuation. Measurements of the air-fluidized oil-filled spheres and mustard seeds at different degrees of fluidization and grain volume fractions provide the velocity autocorrelation that differs from the commonly anticipated exponential Enskog decay. An empiric formula, which corresponds to the model of grain caging at collisions with adjacent beads, fits well to the experimental data. Its parameters are the characteristic collision time, the free path between collisions and the cage-breaking rate or the diffusion-like constant, which decreases with increasing grain volume fraction. Mean-squared displacements calculated from the correlation spectrum clearly show transitions from ballistic, through sub-diffusion and into diffusion regimes of grain motion.

  10. Measurement of Heteronuclear Dipolar Coupling by Transferred-Echo Double-Resonance NMR

    NASA Astrophysics Data System (ADS)

    Hing, A. W.; Vega, S.; Schaefer, J.

    A magic-angle spinning experiment called transferred-echo double resonance (TEDOR) has been introduced recently to measure the I-S dipolar coupling of heteronuclear I-S pairs of spin- {1}/{2} nuclei while eliminating unwanted background signals from uncoupled I and S spins via a coherence-transfer process. In this paper, a quantitative description of the TEDOR experiment is given in terms of the evolution of the density matrix for a pair of heteronuclear spins. The resulting equations provide a theoretical basis for evaluating the selectivity and sensitivity of TEDOR and suggest strategies for determining dipolar coupling constants directly from TEDOR data. Experimental examples illustrating these aspects of TEDOR are provided by studies performed on a range of 13C- 15N dipolar couplings found in double-labeled asparagine, alanine, glycine, and the linear peptide antibiotic, gramicidin.

  11. “CLASSIC NMR”: An In-Situ NMR Strategy for Mapping the Time-Evolution of Crystallization Processes by Combined Liquid-State and Solid-State Measurements**

    PubMed Central

    Hughes, Colan E; Williams, P Andrew; Harris, Kenneth D M

    2014-01-01

    A new in-situ NMR strategy (termed CLASSIC NMR) for mapping the evolution of crystallization processes is reported, involving simultaneous measurement of both liquid-state and solid-state NMR spectra as a function of time. This combined strategy allows complementary information to be obtained on the evolution of both the solid and liquid phases during the crystallization process. In particular, as crystallization proceeds (monitored by solid-state NMR), the solution state becomes more dilute, leading to changes in solution-state speciation and the modes of molecular aggregation in solution, which are monitored by liquid-state NMR. The CLASSIC NMR experiment is applied here to yield new insights into the crystallization of m-aminobenzoic acid. PMID:25044662

  12. Effect of acute stresses on zebra fish (Danio rerio) metabolome measured by NMR-based metabolomics.

    PubMed

    Mushtaq, Mian Yahya; Marçal, Rosilene Moretti; Champagne, Danielle L; van der Kooy, Frank; Verpoorte, Robert; Choi, Young Hae

    2014-09-01

    We applied an acute stress model to zebra fish in order to measure the changes in the metabolome due to biological stress. This was done by submitting the fish to fifteen minutes of acute confinement (netting) stress, and then five minutes for the open field and light/dark field tests. A polar extract of the zebra fish was then subjected to (1)H nuclear magnetic spectroscopy. Multivariate data analysis of the spectra showed a clear separation associated to a wide range of metabolites between zebra fish that were submitted to open field and light/dark field tests. Alanine, taurine, adenosine, creatine, lactate, and histidine were high in zebra fish to which the light/dark field test was applied, regardless of stress, while acetate and isoleucine/lipids appeared to be higher in zebra fish exposed to the open field test. These results show that any change in the environment, even for a small period of time, has a noticeable physiological impact. This research provides an insight of how different mechanisms are activated under different environments to maintain the homeostasis of the body. It should also contribute to establish zebra fish as a model for metabolomics studies. PMID:25098933

  13. Structure and dynamics of water in tendon from NMR relaxation measurements.

    PubMed Central

    Peto, S; Gillis, P; Henri, V P

    1990-01-01

    Nuclear magnetic relaxation times were measured in collagen tissue when varying the orientation of the fiber with respect to the static field. T1 was found to be only slightly dependent on theta, the fiber-to-field angle, but T2 was very sensitive to the orientation, with a maximum value at the magic angle. The transverse decay curves were multiexponential. Their deconvolution displayed four components; the ones that decayed most slowly were almost independent of theta, but the two fastest ones showed a strong angular dependence that was interpreted with a cross-relaxation model. Quadrupolar dips were visible in the 1/T1 dispersion curves. These dips were independent of theta, so that the magnetization transfer could also be assumed to be independent of the fiber orientation. Finally, each component was assigned to a fraction of protons localized in the macromolecular structure and characterized by particular dynamics. The model of Woessner was applied to the water molecules tightly bound into the macromolecules, which resulted in a dynamical description of this water fraction. This description is compatible with the two-sites model of Ramachandran based on x-ray diffraction and with the extensive studies of Berendsen. However, the important indications obtained from the deconvolution lead to a less static representation of the tissue. PMID:2297563

  14. Diffusion of CO2 in n-hexadecane determined from NMR relaxometry measurements

    NASA Astrophysics Data System (ADS)

    Hao, Min; Song, Yongchen; Su, Bo; Zhao, Yuechao

    2015-06-01

    In this study, we discuss the feasibility in computation of diffusion coefficient (D) using the longitudinal relaxation time T1. CO2-n-hexadecane in pure solutions and in a porous medium was tested separately by measuring the T1 of n-hexadecane at varying CO2 concentration (c). The relationship between T1 and c was correlated. The results show that T1 exponentially rises with the increase of c. Thus, we proposed the method to estimate D of CO2 using T1 through the relationship above and Fick's law. We computed D from T1 and compared this method with the traditional method. The two methods agree well with differences less than 10%. The new method is characterized by simpleness, convenience and flexibility, as it computes D with the only requirement of monitoring T1. This new method will guide the use of nuclear magnetic resonance logging in in-field testing of CO2 diffusion and migration laws.

  15. Approximation and noise errors of measured T/sub 1/ in NMR imaging

    SciTech Connect

    Persyk, D.E.

    1984-01-01

    Photomultiplier tubes (PMTs) of various types from four manufacturers were measured to determine their gain drift characteristics. This was in turn related to retuning frequency in Anger cameras. A well stabilized light source illuminated sets of thirty-seven PMTs, simulating ideal steady-state conditions in an Anger camera. Anode outputs were sampled at six minute intervals for periods of up to three weeks using a multichannel data logger. Data were analyzed off line. It was found that PMT gains diverged form their initial values at a rate which decreased with time. The standard deviation of the gain changes, called drift, was plotted versus time. Drift was found to generally obey a power law function: D(%) = 0.16 x t/sup 0.6/ where t is the elapsed time in hours. In testing thousands of PMTs the authors occasionally found ''flyers'' with drift rates considerably larger than the average. The authors conclude that with sets of carefully selected PMTs the frequency of tuning would generally decrease as the tubes age. They also conclude that the presence of an occasional ''flyer'' PMT in a camera would undoubtedly necessitate more frequent tuning, in some cases on a weekly basis. These findings support the observed wide variation in tuning frequency among Anger cameras without active PMT gain compensation.

  16. Electrophoretic Porosimetry of Sol-Gels

    NASA Technical Reports Server (NTRS)

    Snow, L. A.; Smith, D. D.; Sibille, L.; Hunt, A. J.; Ng, J.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    It has been hypothesized that gravity has an effect on the formation and resulting microstructure of sol-gels. In order to more clearly resolve the effect of gravity, pores may be non-destructively analyzed in the wet gel, circumventing the shrinkage and coarsening associated with the drying procedure. We discuss the development of an electrophoretic technique, analogous to affinity chromatography, for the determination of pore size distribution and its application to silica gels. Specifically a monodisperse charged dye is monitored by an optical densitometer as it moves through the wet gel under the influence of an electric field. The transmittance data (output) represents the convolution of the dye concentration profile at the beginning of the run (input) with the pore size distribution (transfer function), i.e. linear systems theory applies. Because of the practical difficulty in producing a delta function input dye profile we prefer instead to use a step function. Average pore size is then related to the velocity of this dye front, while the pore size distribution is related to the spreading of the front. Preliminary results of this electrophoretic porosimetry and its application to ground and space-grown samples will be discussed.

  17. Solid State NMR Measurements for Preliminary Lifetime Assessments in (gamma)-Irradiated and Thermally Aged Siloxane Elastomers

    SciTech Connect

    Chinn, S C; Herberg, J L; Sawvel, A M; Maxwell, R S

    2005-02-03

    Siloxanes have a wide variety of applications throughout the aerospace industry which take advantage of their exceptional insulating and adhesive properties and general resilience. They also offer a wide range of tailorable engineering properties with changes in composition and filler content. They are, however, subject to degradation in radiatively and thermally harsh environments. We are using solid state nuclear magnetic resonance techniques to investigate changes in network and interfacial structure in siloxane elastomers and their correlations to changes in engineering performance in a series of degraded materials. Nuclear magnetic resonance (NMR) parameters such as transverse (T{sub 2}) relaxation times, cross relaxation rates, and residual dipolar coupling constants provide excellent probes of changes crosslink density and motional dynamics of the polymers caused by multi-mechanism degradation. The results of NMR studies on aged siloxanes are being used in conjunction with other mechanical tests to provide insight into component failure and degradation kinetics necessary for preliminary lifetime assessments of these materials as well as into the structure-property relationships of the polymers. NMR and magnetic resonance imaging (MRI) results obtained both from high resolution NMR spectrometers as well as low resolution benchtop NMR screening tools will be presented.

  18. Solid State NMR Measurements for Preliminary Lifetime Assessments in gamma-Irradiated and Thermally Aged Siloxane Elastomers

    SciTech Connect

    Chinn, S C; Herberg, J L; Sawvel, A M; Maxwell, R S

    2004-11-29

    Siloxanes have a wide variety of applications throughout the aerospace industry which take advantage of their exceptional insulating and adhesive properties and general resilience. They also offer a wide range of tailorable engineering properties with changes in composition and filler content. They are, however, subject to degradation in radiatively and thermally harsh environments. We are using solid state nuclear magnetic resonance techniques to investigate changes in network and interfacial structure in siloxane elastomers and their correlations to changes in engineering performance in a series of degraded materials. NMR parameters such as transverse ( T{sub 2}) relaxation times, cross relaxation rates, and residual dipolar coupling constants provide excellent probes of changes crosslink density and motional dynamics of the polymers caused by multi-mechanism degradation. The results of NMR studies on aged siloxanes are being used in conjunction with other mechanical tests to provide insight into component failure and degradation kinetics necessary for preliminary lifetime assessments of these materials as well as into the structure-property relationships of the polymers. NMR and MRI results obtained both from high resolution NMR spectrometers as well as low resolution benchtop NMR screening tools will be presented.

  19. Electrophoretic mobility of particles in concentrated solutions of electrolytes

    SciTech Connect

    Deinega, Yu.F.; Polyakova, V.M.; Aleksandrova, L.N.

    1986-11-01

    The electrophoretic mobility of particles of phenol-formaldehyde and aniline-formaldehyde resins in zinc sulfate solutions has been investigated. It is shown that as the electrolyte concentration rises, the electrophoretic mobility falls, reaches a minimum, and then increases. A possible mechanism for the formation of an electric double layer on the surface of particles in concentrated solutions of electrolytes is proposed.

  20. Comparison of surface NMR with non-invasive and in-situ measurements of soil water content at a floodplain field site

    NASA Astrophysics Data System (ADS)

    Werban, Ulrike; Schrön, Martin; Dietrich, Peter; Walsh, David; Grunewald, Elliot; Pohle, Marco; Kathage, Susanne

    2016-04-01

    Quantification of soil water content is a very relevant issue in soil and environmental studies. There is a broad spectrum of methods applied for measuring soil water content in the field either deployed in situ or non-invasively from the surface. For many reasons the latter is preferred in field studies. Nuclear Magnetic Resonance (NMR) is one of the rare methods that measure the water content directly. Whereas others, e.g. geophysical methods, make use of proximal relationships for determination of soil water content. We applied a new single-sided NMR sensor to non-invasively measure in-situ soil moisture profiles at several points along two transects in a floodplain. The field site exhibits variations in soil water content due to morphology, e.g. flood channels and alluvial fan structures. Furthermore we applied at the same transects (1) in situ methods: soil sampling for gravimetrical analysis and TDR and (2) non-invasive methods: electromagnetical induction, mobile cosmic-ray neutron sensing with a rover and gamma-ray spectrometry. We will present results that confirm agreement of NMR and gravimetrical analysis from soil sampling and discuss issues that arise when using non-unique proxy methods and relationships for determination of soil water content.

  1. Electrophoretic Deposition on Porous Non-Conductors

    NASA Technical Reports Server (NTRS)

    Compson, Charles; Besra, Laxmidhar; Liu, Meilin

    2007-01-01

    A method of electrophoretic deposition (EPD) on substrates that are porous and electrically non-conductive has been invented. Heretofore, in order to perform an EPD, it has been necessary to either (1) use a substrate material that is inherently electrically conductive or (2) subject a non-conductive substrate to a thermal and/or chemical treatment to render it conductive. In the present method, instead of relying on the electrical conductivity of the substrate, one ensures that the substrate is porous enough that when it is immersed in an EPD bath, the solvent penetrates throughout the thickness, thereby forming quasi-conductive paths through the substrate. By making it unnecessary to use a conductive substrate, this method simplifies the overall EPD process and makes new applications possible. The method is expected to be especially beneficial in enabling deposition of layers of ceramic and/or metal for chemical and electrochemical devices, notably including solid oxide fuel cells.

  2. SPAR electrophoretic separation experiments, part 2

    NASA Technical Reports Server (NTRS)

    Cosmi, F. M.

    1978-01-01

    The opportunity to use a sounding rocket for separation experiments is a logical continuation of earlier electrophoresis demonstrations and experiments. A free-flow electrophoresis system, developed under the Advanced Applications Flight Experiment (AAFE) Program, was designed so that it would fit into a rocket payload. The SPAR program provides a unique opportunity to complete the intial stages of microgravity testing prior to any Shuttle applications. The objective of the work described in this report was to ensure proper operating parameters for the defined experimental samples to be used in the SPAR Electrophoretic Separation Experiment. Ground based experiments were undertaken not only to define flight parameters but also to serve as a point of comparison for flight results. Possible flight experiment problem areas were also studied such as sample interaction due to sedimentation, concentration effects and storage effects. Late in the program anomalies of field strengths and buffer conductivities were also investigated.

  3. Recent patents on electrophoretic displays and materials.

    PubMed

    Christophersen, Marc; Phlips, Bernard F

    2010-11-01

    Electrophoretic displays (EPDs) have made their way into consumer products. EPDs enable displays that offer the look and form of a printed page, often called "electronic paper". We will review recent apparatus and method patents for EPD devices and their fabrication. A brief introduction into the basic display operation and history of EPDs is given, while pointing out the technological challenges and difficulties for inventors. Recently, the majority of scientific publications and patenting activity has been directed to micro-segmented EPDs. These devices exhibit high optical reflectance and contrast, wide viewing angle, and high image resolution. Micro-segmented EPDs can also be integrated with flexible transistors technologies into flexible displays. Typical particles size ranges from 200 nm to 2 micrometer. Currently one very active area of patenting is the development of full-color EPDs. We summarize the recent patenting activity for EPDs and provide comments on perceiving factors driving intellectual property protection for EPD technologies. PMID:20565384

  4. Electrochemically powered self-propelled electrophoretic nanosubmarines

    NASA Astrophysics Data System (ADS)

    Pumera, Martin

    2010-09-01

    In the past few years, we have witnessed rapid developments in the realization of the old nanotechnology dream, autonomous nanosubmarines. These nanomachines are self-powered, taking energy from their environment by electrocatalytic conversion of chemicals present in the solution, self-propelled by flux of the electrons within the submarine and the hydronium ions on the surface of the nanosub, powering it in the direction opposite to that of the flux of the hydronium. These nanosubmarines are responsive to external fields, able to follow complex magnetic patterns, navigate themselves in complex microfluidic channels, follow chemical gradients, carry cargo, and communicate with each other. This minireview focuses on a discussion of the fundamentals of the electrophoretic mechanism underlying the propulsion of this sort of nanosub, as well as a demonstration of the proof-of-concept capabilities of nanosubmarines.In the past few years, we have witnessed rapid developments in the realization of the old nanotechnology dream, autonomous nanosubmarines. These nanomachines are self-powered, taking energy from their environment by electrocatalytic conversion of chemicals present in the solution, self-propelled by flux of the electrons within the submarine and the hydronium ions on the surface of the nanosub, powering it in the direction opposite to that of the flux of the hydronium. These nanosubmarines are responsive to external fields, able to follow complex magnetic patterns, navigate themselves in complex microfluidic channels, follow chemical gradients, carry cargo, and communicate with each other. This minireview focuses on a discussion of the fundamentals of the electrophoretic mechanism underlying the propulsion of this sort of nanosub, as well as a demonstration of the proof-of-concept capabilities of nanosubmarines. In memory of Karel Zeman, Czech animator, who encouraged thousands of young people into science and technology, on the occasion of the 100th

  5. High-resolution slice selection NMR for the measurement of CO2 diffusion under non-equilibrium conditions.

    PubMed

    Allen, Jesse; Damodaran, Krishnan

    2015-03-01

    We present a simple and an efficient approach using spatially selective NMR to investigate solvation and diffusion of CO2 in ionic liquids. The techniques demonstrated here are shown as novel and effective means of studying solvated gas dynamics under non-equilibrium conditions without the need for conventional high power gradients. PMID:25353108

  6. [ 31P]NMR measurements of hexokinase activity in intact red blood cells with 2-deoxyglucose as substrate

    NASA Astrophysics Data System (ADS)

    Halabi, F.; Seguin, J. P.; Fonroget, J.; Goethals, G.

    [ 31P] NMR spectroscopy is demonstrated to be a suitable tool to follow the time course of 2-deoxyglucose-6-phosphate in intact human erythrocytes incubated with 2-deoxyglucose. It allowed to determine hexokinase Vmax and K m in near physiological conditions.

  7. Non-invasive and quantitative evaluation of peripheral vascular resistances in rats by combined NMR measurements of perfusion and blood pressure using ASL and dynamic angiography.

    PubMed

    Ménard, Jacques C; Giacomini, Eric; Baligand, Céline; Fromes, Yves; Carlier, Pierre G

    2010-02-01

    The in vivo determination of peripheral vascular resistances (VR) is crucial for the assessment of arteriolar function. It requires simultaneous determination of organ perfusion (F) and arterial blood pressure (BP). A fully non-invasive method was developed to measure systolic and diastolic BP in the caudal artery of rats based on dynamic NMR angiography. A good agreement was found between the NMR approach and the gold standard techniques (linear regression slope = 0.98, R(2) = 0.96). This method and the ASL-MRI measurement of skeletal muscle perfusion were combined into one single NMR experiment to quantitatively evaluate the local vascular resistances in the calf muscle of anaesthetized rats, in vivo and non-invasively 1) at rest: VR = 7.0 +/- 1.0 mmHg x min 100 g x ml(-1), F = 13 +/- 3 ml min(-1) x 100 g(-1) and mean BP (MBP) = 88 +/- 10 mmHg; 2) under vasodilator challenge (milrinone): VR = 3.7 +/- 1.1 mmHg min x 100 g ml(-1), F = 21 +/- 4 ml min(-1) x 100 g(-1) and MBP = 75 +/- 14 mmHg; 3) under vasopressor challenge (norepinephrine): VR = 9.8 +/- 1.2 mmHg min 100 g ml(-1), F = 14 +/- 3 ml min(-1) x 100 g(-1) and MBP = 137 +/- 2 mmHg. PMID:19795372

  8. The structure investigations of dehydroacetic acid and 1,8-diaminonaphthalene condensation product by NMR, MS, and X-ray measurements

    NASA Astrophysics Data System (ADS)

    Kołodziej, B.; Morawiak, M.; Kamieński, B.; Schilf, W.

    2016-05-01

    A new unexpected product of condensation reaction of 1,8-diaminonaphthalene (DAN) and carbonyl compound (here: dehydroacetic acid (dha)) was synthesized. Discussion about the molecular structure of possible products of this reaction was done on the base of NMR studies. The structure of the titled product in both DMSO solution and in the solid state was resolved by analysis of its spectral data (X-ray structure analysis, multinuclear NMR in solution and solid state spectra) and MS measurements. The presented studies provided clear evidence that the titled product exists in diluted DMSO solution as the mixture of two kinetic free ionic species whereas in concentrated DMSO solution as well as in the solid state this system forms associated ionic pairs bonded together by hydrogen bonds.

  9. Suppression of electron correlations in the collapsed tetragonal phase of CaFe2As2 under ambient pressure demonstrated by As75 NMR/NQR measurements

    SciTech Connect

    Furukawa, Yuji; Roy, Beas; Ran, Sheng; Budko, Sergey L.; Canfield, Paul C.

    2014-03-20

    The static and the dynamic spin correlations in the low-temperature collapsed tetragonal and the high-temperature tetragonal phase in CaFe2As2 have been investigated by As75 nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. Through the temperature (T) dependence of the nuclear spin lattice relaxation rates (1/T1) and the Knight shifts, although stripe-type antiferromagnetic (AFM) spin correlations are realized in the high-temperature tetragonal phase, no trace of the AFM spin correlations can be found in the nonsuperconducting, low-temperature, collapsed tetragonal (cT) phase. Given that there is no magnetic broadening in As75 NMR spectra, together with the T-independent behavior of magnetic susceptibility χ and the T dependence of 1/T1Tχ, we conclude that Fe spin correlations are completely quenched statically and dynamically in the nonsuperconducting cT phase in CaFe2As2.

  10. Suppression of electron correlations in the collapsed tetragonal phase of CaFe2As2 under ambient pressure demonstrated by As75 NMR/NQR measurements

    NASA Astrophysics Data System (ADS)

    Furukawa, Y.; Roy, B.; Ran, S.; Bud'ko, S. L.; Canfield, P. C.

    2014-03-01

    The static and the dynamic spin correlations in the low-temperature collapsed tetragonal and the high-temperature tetragonal phase in CaFe2As2 have been investigated by As75 nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. Through the temperature (T) dependence of the nuclear spin lattice relaxation rates (1/T1) and the Knight shifts, although stripe-type antiferromagnetic (AFM) spin correlations are realized in the high-temperature tetragonal phase, no trace of the AFM spin correlations can be found in the nonsuperconducting, low-temperature, collapsed tetragonal (cT) phase. Given that there is no magnetic broadening in As75 NMR spectra, together with the T-independent behavior of magnetic susceptibility χ and the T dependence of 1/T1Tχ, we conclude that Fe spin correlations are completely quenched statically and dynamically in the nonsuperconducting cT phase in CaFe2As2.

  11. Dual Species NMR Oscillator

    NASA Astrophysics Data System (ADS)

    Weber, Joshua; Korver, Anna; Thrasher, Daniel; Walker, Thad

    2016-05-01

    We present progress towards a dual species nuclear magnetic oscillator using synchronous spin exchange optical pumping. By applying the bias field as a sequence of alkali 2 π pulses, we generate alkali polarization transverse to the bias field. The alkali polarization is then modulated at the noble gas resonance so that through spin exchange collisions the noble gas becomes polarized. This novel method of NMR suppresses the alkali field frequency shift by at least a factor of 2500 as compared to longitudinal NMR. We will present details of the apparatus and measurements of dual species co-magnetometry using this method. Research supported by the NSF and Northrop-Grumman Corp.

  12. Acceleration of natural-abundance solid-state MAS NMR measurements on bone by paramagnetic relaxation from gadolinium-DTPA.

    PubMed

    Mroue, Kamal H; Zhang, Rongchun; Zhu, Peizhi; McNerny, Erin; Kohn, David H; Morris, Michael D; Ramamoorthy, Ayyalusamy

    2014-07-01

    Reducing the data collection time without affecting the signal intensity and spectral resolution is one of the major challenges for the widespread application of multidimensional nuclear magnetic resonance (NMR) spectroscopy, especially in experiments conducted on complex heterogeneous biological systems such as bone. In most of these experiments, the NMR data collection time is ultimately governed by the proton spin-lattice relaxation times (T1). For over two decades, gadolinium(III)-DTPA (Gd-DTPA, DTPA=Diethylene triamine pentaacetic acid) has been one of the most widely used contrast-enhancement agents in magnetic resonance imaging (MRI). In this study, we demonstrate that Gd-DTPA can also be effectively used to enhance the longitudinal relaxation rates of protons in solid-state NMR experiments conducted on bone without significant line-broadening and chemical-shift-perturbation side effects. Using bovine cortical bone samples incubated in different concentrations of Gd-DTPA complex, the (1)H T1 values were calculated from data collected by (1)H spin-inversion recovery method detected in natural-abundance (13)C cross-polarization magic angle spinning (CPMAS) NMR experiments. Our results reveal that the (1)H T1 values can be successfully reduced by a factor of 3.5 using as low as 10mM Gd-DTPA without reducing the spectral resolution and thus enabling faster data acquisition of the (13)C CPMAS spectra. These results obtained from (13)C-detected CPMAS experiments were further confirmed using (1)H-detected ultrafast MAS experiments on Gd-DTPA doped bone samples. This approach considerably improves the signal-to-noise ratio per unit time of NMR experiments applied to bone samples by reducing the experimental time required to acquire the same number of scans. PMID:24881032

  13. Acceleration of natural-abundance solid-state MAS NMR measurements on bone by paramagnetic relaxation from gadolinium-DTPA

    NASA Astrophysics Data System (ADS)

    Mroue, Kamal H.; Zhang, Rongchun; Zhu, Peizhi; McNerny, Erin; Kohn, David H.; Morris, Michael D.; Ramamoorthy, Ayyalusamy

    2014-07-01

    Reducing the data collection time without affecting the signal intensity and spectral resolution is one of the major challenges for the widespread application of multidimensional nuclear magnetic resonance (NMR) spectroscopy, especially in experiments conducted on complex heterogeneous biological systems such as bone. In most of these experiments, the NMR data collection time is ultimately governed by the proton spin-lattice relaxation times (T1). For over two decades, gadolinium(III)-DTPA (Gd-DTPA, DTPA = Diethylene triamine pentaacetic acid) has been one of the most widely used contrast-enhancement agents in magnetic resonance imaging (MRI). In this study, we demonstrate that Gd-DTPA can also be effectively used to enhance the longitudinal relaxation rates of protons in solid-state NMR experiments conducted on bone without significant line-broadening and chemical-shift-perturbation side effects. Using bovine cortical bone samples incubated in different concentrations of Gd-DTPA complex, the 1H T1 values were calculated from data collected by 1H spin-inversion recovery method detected in natural-abundance 13C cross-polarization magic angle spinning (CPMAS) NMR experiments. Our results reveal that the 1H T1 values can be successfully reduced by a factor of 3.5 using as low as 10 mM Gd-DTPA without reducing the spectral resolution and thus enabling faster data acquisition of the 13C CPMAS spectra. These results obtained from 13C-detected CPMAS experiments were further confirmed using 1H-detected ultrafast MAS experiments on Gd-DTPA doped bone samples. This approach considerably improves the signal-to-noise ratio per unit time of NMR experiments applied to bone samples by reducing the experimental time required to acquire the same number of scans.

  14. Acceleration of Natural-Abundance Solid-State MAS NMR Measurements on Bone by Paramagnetic Relaxation from Gadolinium-DTPA

    PubMed Central

    Mroue, Kamal H.; Zhang, Rongchun; Zhu, Peizhi; McNerny, Erin; Kohn, David H.; Morris, Michael D.; Ramamoorthy, Ayyalusamy

    2014-01-01

    Reducing the data collection time without affecting the signal intensity and spectral resolution is one of the major challenges for the widespread application of multidimensional nuclear magnetic resonance (NMR) spectroscopy, especially in experiments conducted on complex heterogeneous biological systems such as bone. In most of these experiments, the NMR data collection time is ultimately governed by the proton spin-lattice relaxation times (T1). For over two decades, gadolinium(III)-DTPA (Gd-DTPA, DTPA = Diethylenetriamine pentaacetic acid) has been one of the most widely used contrast-enhancement agents in magnetic resonance imaging (MRI). In this study, we demonstrate that Gd-DTPA can also be effectively used to enhance the longitudinal relaxation rates of protons in solid-state NMR experiments conducted on bone without significant line-broadening and chemical-shift-perturbation side effects. Using bovine cortical bone samples incubated in different concentrations of Gd-DTPA complex, the 1H T1 values were calculated from data collected by 1H spin-inversion recovery method detected in natural-abundance 13C cross-polarization magic angle spinning (CPMAS) NMR experiments. Our results reveal that the 1H T1 values can be successfully reduced by a factor of 3.5 using as low as 10 mM Gd-DTPA without reducing the spectral resolution and thus enabling faster data acquisition of the 13C CPMAS spectra. These results obtained from 13C-detected CPMAS experiments were further confirmed using 1H-detected ultrafast MAS experiments on Gd-DTPA doped bone samples. This approach considerably improves the signal-to-noise ratio per unit time of NMR experiments applied to bone samples by reducing the experimental time required to acquire the same number of scans. PMID:24881032

  15. Charge carrier effective mass and concentration derived from combination of Seebeck coefficient and 125Te NMR measurements in complex tellurides

    NASA Astrophysics Data System (ADS)

    Levin, E. M.

    2016-06-01

    Thermoelectric materials utilize the Seebeck effect to convert heat to electrical energy. The Seebeck coefficient (thermopower), S , depends on the free (mobile) carrier concentration, n , and effective mass, m*, as S ˜m*/n2 /3 . The carrier concentration in tellurides can be derived from 125Te nuclear magnetic resonance (NMR) spin-lattice relaxation measurements. The NMR spin-lattice relaxation rate, 1 /T1 , depends on both n and m* as 1 /T1˜(m*)3/2n (within classical Maxwell-Boltzmann statistics) or as 1 /T1˜(m*)2n2 /3 (within quantum Fermi-Dirac statistics), which challenges the correct determination of the carrier concentration in some materials by NMR. Here it is shown that the combination of the Seebeck coefficient and 125Te NMR spin-lattice relaxation measurements in complex tellurides provides a unique opportunity to derive the carrier effective mass and then to calculate the carrier concentration. This approach was used to study A gxS bxG e50-2xT e50 , well-known GeTe-based high-efficiency tellurium-antimony-germanium-silver thermoelectric materials, where the replacement of Ge by [Ag+Sb] results in significant enhancement of the Seebeck coefficient. Values of both m* and n derived using this combination show that the enhancement of thermopower can be attributed primarily to an increase of the carrier effective mass and partially to a decrease of the carrier concentration when the [Ag+Sb] content increases.

  16. Cell and Particle Interactions and Aggregation During Electrophoretic Motion

    NASA Technical Reports Server (NTRS)

    Wang, Hua; Zeng, Shulin; Loewenberg, Michael; Todd, Paul; Davis, Robert H.

    1996-01-01

    The stability and pairwise aggregation rates of small spherical particles under the collective effects of buoyancy-driven motion and electrophoretic migration are analyzed. The particles are assumed to be non-Brownian, with thin double-layers and different zeta potentials. The particle aggregation rates may be enhanced or reduced, respectively, by parallel and antiparallel alignments of the buoyancy-driven and electrophoretic velocities. For antiparallel alignments, with the buoyancy-driven relative velocity exceeding the electrophoretic relative velocity between two widely-separated particles, there is a 'collision-forbidden region' in parameter space due to hydrodynamic interactions; thus, the suspension becomes stable against aggregation.

  17. Measurement and assignment of long-range C-H dipolar couplings in liquid crystals by two-dimensional NMR spectroscopy

    SciTech Connect

    Hong, M.; Pines, A. |; Caldarelli, S.

    1996-08-29

    We describe multidimensional NMR techniques to measure and assign {sup 13}C-{sup 1}H dipolar couplings in nematic liquid crystals with high resolution. In particular, dipolar couplings between aromatic and aliphatic sites are extracted, providing valuable information on the structural correlations between these two components of thermotropic liquid crystal molecules. The NMR techniques are demonstrated on 4-pentyl-4`-biphenylcarbonitrile (5CB), a well-characterized room-temperature nematic liquid crystal. Proton-detected local-field NMR spectroscopy is employed to obtain highly resolved C-H dipolar couplings that are separated according to the chemical shifts of the carbon sites. Each {sup 13}C cross section in the 2D spectra exhibits several doublet splittings, with the largest one resulting from the directly bonded C-H coupling. The smaller splittings originate from the long-range C-H dipolar couplings and can be assigned qualitatively by a chemical shift heteronuclear correlation (HETCOR) experiment. The HETCOR experiment incorporates a mixing period for proton spin diffusion to occur, so that maximal polarization transfer can be achieved between the unbonded {sup 13}C and {sup 1}H nuclei. To assign the long-range C-H couplings quantitatively. we combined these two techniques into a novel reduced-3D experiment, in which the {sup 1}H chemical shift-displaced C-H dipolar couplings are correlated with the {sup 13}C chemical shifts. 34 refs., 6 figs., 2 tabs.

  18. Still shimming or already measuring? - Quantitative reaction monitoring for small molecules on the sub minute timescale by NMR

    NASA Astrophysics Data System (ADS)

    Kind, J.; Thiele, C. M.

    2015-11-01

    In order to enable monitoring of rapidly occurring reactions Wagner et al. recently presented a simple scheme for 1D NMR experiments with continuous data acquisition, without inter-scan delays, using a spatially-selective and frequency-shifted excitation approach (Wagner et al., 2013). This scheme allows acquisition of proton spectra with temporal resolutions on the millisecond timescale. Such high temporal resolutions are desired in the case of reaction monitoring using stopped flow setups. In regular 1H NMR-spectra without spatial selection the line width increases for a given shim setting with changes in sample volume, susceptibility, convection and temperature or concentration gradients due to the disturbance of magnetic field homogeneity. Concerning reaction monitoring this is unfortunate as shimming prior to acquisition becomes necessary to obtain narrow signals after injection of a reactant into an NMR sample. Even automatic shim routines may last up to minutes. Thus fast reactions can hardly be monitored online without large hardware dead times in a single stopped flow experiment. This problem is reduced in the spatially-selective and frequency-shifted continuous NMR experiment as magnetic field inhomogeneties are less pronounced and negative effects on the obtained line shapes are reduced as pointed out by Bax and Freeman (1980) [2] and demonstrated by Wagner et al. (2013). Here we present the utilization of this technique for observation of reactions in small molecule systems in which chemical conversion and longitudinal relaxation occur on the same timescale. By means of the alkaline ethyl acetate hydrolysis, a stoichiometric reaction, we show advantages of spatially-selective excitation on both temporal resolution and line shapes in stopped flow experiments. Results are compared to data obtained by non-selective small angle excitation experiments.

  19. Evidence for s-wave superconductivity in noncentrosymmetric Re24Nb5 from 93Nb NMR measurements

    NASA Astrophysics Data System (ADS)

    Lue, C. S.; Su, T. H.; Liu, H. F.; Young, Ben-Li

    2011-08-01

    We report a 93Nb nuclear magnetic resonance (NMR) study on the noncentrosymmetric superconductor Re24Nb5. Below the superconducting temperature Tc(H), the spin susceptibility probed by the 93Nb NMR Knight shift gradually decreases with lowering temperature, accompanied by the broadening of the resonance spectrum. Such behavior is commonly observed in the BCS-type superconductors. The 93Nb NMR spin-lattice relaxation rate (1/T1) shows a well-defined coherence peak just below Tc(H), followed by a marked decrease with further decreasing temperature. Moreover, the 1/T1 data in the superconducting state were found to obey a single exponential expression, yielding a nodeless gap Δ/kB=10.3 K. This value gives the ratio of 2Δ/kBTc(H)=3.55, that is almost identical with the value of 3.5 predicted from BCS theory. On these bases, we conclude that the noncentrosymmetric Re24Nb5 compound can be characterized as a weakly coupled BCS-type superconductor.

  20. An electrophoretic profiling method for thiol-rich phytochelatins and metallothioneins.

    PubMed

    Fan, Teresa W M; Lane, Andrew N; Higashi, Richard M

    2004-01-01

    Thiol-rich peptides such as phytochelatins (PCs) and metallothioneins (MTs) are important cellular chelating agents which function in metal detoxification and/or homeostasis. The variations in molecular sizes and lack of chromophores of these peptides make their analysis difficult. This paper reports an electrophoresis-based method for a broad screen of thiol-rich peptides and proteins. The method uses the thiol-selective fluorescent tag, monobromobimane, coupled with Tricine--sodium dodecyl sulphate--urea polyacrylamide gel electrophoresis for a sensitive determination of both PCs and MTs. Results for PCs were confirmed by two-dimensional NMR and HPLC-tandem MS analyses. Sample throughput is substantially improved over chromatography-based methods through parallel sample analysis in 1 h of electrophoretic separation. The method is versatile in that peptides ranging from glutathione to large proteins can be analysed by simple modification(s) of the extraction and electrophoretic conditions, and the nature of the method supports serendipitous detection of unexpected or novel thiol metabolites. PMID:15202602

  1. Effect of pH on the Electrophoretic Mobility of Spores of Bacillus anthracis and Its Surrogates in Aqueous Solutions

    EPA Science Inventory

    Electrophoretic mobility (EPM) of endospores of Bacillus anthracis and surrogates were measured in aqueous solution across a broad pH range and several ionic strengths. EPM values trended around phylogenetic clustering based on the 16S rRNA gene. Measurements reported here prov...

  2. 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

  3. THz Dynamic Nuclear Polarization NMR.

    PubMed

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

    2011-08-29

    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

  4. MICROSPORIDIAN TAXONOMY: APPLICATION OF ELECTROPHORETIC AND IMMUNOLOGICAL TECHNIQUES

    EPA Science Inventory

    A review of investigations utilizing electrophoretic and immunological methods for identification and classification of microsporidians, the group to which the first protozoan microbial pesticide belongs, indicate that these methods can be successfully used to classify strains an...

  5. Cell and Particle Interactions and Aggregation During Electrophoretic Motion

    NASA Technical Reports Server (NTRS)

    Davis, Robert H.

    2000-01-01

    The objectives of this research were (i) to perform experiments for observing and quantifying electrophoretic aggregation, (ii) to develop a theoretical description to appropriately analyze and compare with the experimental results, (iii) to study the combined effects of electrophoretic and gravitational aggregation of large particles, and the combined effects of electrophoretic and Brownian aggregation of small particles, and (iv) to perform a preliminary design of a potential future flight experiment involving electrophoretic aggregation. Electrophoresis refers to the motion of charged particles, droplets or molecules in response to an applied electric field. Electrophoresis is commonly used for analysis and separation of biological particles or molecules. When particles have different surface charge densities or potentials, they will migrate at different velocities in an electric field. This differential migration leads to the possibility that they will collide and aggregate, thereby preventing separation.

  6. Fluid Delivery System For Capillary Electrophoretic Applications.

    DOEpatents

    Li, Qingbo; Liu, Changsheng; Kane, Thomas E.; Kernan, John R.; Sonnenschein, Bernard; Sharer, Michael V.

    2002-04-23

    An automated electrophoretic system is disclosed. The system employs a capillary cartridge having a plurality of capillary tubes. The cartridge has a first array of capillary ends projecting from one side of a plate. The first array of capillary ends are spaced apart in substantially the same manner as the wells of a microtitre tray of standard size. This allows one to simultaneously perform capillary electrophoresis on samples present in each of the wells of the tray. The system includes a stacked, dual carrousel arrangement to eliminate cross-contamination resulting from reuse of the same buffer tray on consecutive executions from electrophoresis. The system also has a gel delivery module containing a gel syringe/a stepper motor or a high pressure chamber with a pump to quickly and uniformly deliver gel through the capillary tubes. The system further includes a multi-wavelength beam generator to generate a laser beam which produces a beam with a wide range of wavelengths. An off-line capillary reconditioner thoroughly cleans a capillary cartridge to enable simultaneous execution of electrophoresis with another capillary cartridge. The streamlined nature of the off-line capillary reconditioner offers the advantage of increased system throughput with a minimal increase in system cost.

  7. Microencapsulated Electrophoretic Films for Electronic Paper Displays

    NASA Astrophysics Data System (ADS)

    Amundson, Karl

    2003-03-01

    Despite the dominance of liquid crystal displays, they do not perform some functions very well. While backlit liquid crystal displays can offer excellent color performance, they wash out in bright lighting and suffer from high power consumption. Reflective liquid crystal displays have limited brightness, making these devices challenging to read for long periods of time. Flexible liquid crystal displays are difficult to manufacture and keep stable. All of these attributes (long battery lifetime, bright reflective appearance, compatibility with flexible substrates) are traits that would be found in an ideal electronic paper display - an updateable substitute for paper that could be employed in electronic books, newspapers, and other applications. I will discuss technologies that are being developed for electronic-paper-like displays, and especially on particle-based technologies. A microencapsulated electrophoretic display technology is being developed at the E Ink corporation. This display film offers offer high brightness and an ink-on-paper appearance, compatibility with flexible substrates, and image stability that can lead to very low power consumption. I will present some of the physical and chemical challenges associated with making display films with high performance.

  8. A lateral electrophoretic flow diagnostic assay

    PubMed Central

    Lin, Robert; Skandarajah, Arunan; Gerver, Rachel E.; Neira, Hector D.; Fletcher, Daniel A.

    2015-01-01

    Immunochromatographic assays are a cornerstone tool in disease screening. To complement existing lateral flow assays (based on wicking flow) we introduce a lateral flow format that employs directed electrophoretic transport. The format is termed a “lateral e-flow assay” and is designed to support multiplexed detection using immobilized reaction volumes of capture antigen. To fabricate the lateral e-flow device, we employ mask-based UV photopatterning to selectively immobilize unmodified capture antigen along the microchannel in a barcode-like pattern. The channel-filling polyacrylamide hydrogel incorporates a photoactive moiety (benzophenone) to immobilize capture antigen to the hydrogel without a priori antigen modification. We report a heterogeneous sandwich assay using low-power electrophoresis to drive biospecimen through the capture antigen barcode. Fluorescence barcode readout is collected via a low-resource appropriate imaging system (CellScope). We characterize lateral e-flow assay performance and demonstrate a serum assay for antibodies to the hepatitis C virus (HCV). In a pilot study, the lateral e-flow assay positively identifies HCV+ human sera in 60 min. The lateral e-flow assay provides a flexible format for conducting multiplexed immunoassays relevant to confirmatory diagnosis in near-patient settings. PMID:25608872

  9. Monodisperse light color nanoparticle ink toward chromatic electrophoretic displays.

    PubMed

    Peng, Bo; Li, Yue; Li, Jian; Bi, Lei; Lu, Haipeng; Xie, Jianliang; Ren, Xiangling; Cao, Yonghai; Wang, Ning; Meng, Xianwei; Deng, Longjiang; Guo, Zhanhu

    2016-06-01

    The facile synthesis of nanoparticles for precise image control and fast response of chromatic electrophoretic displays (EPDs) is a challenge. Herein, we report a general method to prepare pink, blue, and yellow nanoparticles with low density and a tunable size of 230-310 nm. The monodispersity is down to 0.02 and surface charges are up to 666e. Importantly, our work highlights the feasibility of chromatic nanoparticles as cost-effective candidates for electrophoretic displays. PMID:27189743

  10. Viscosity of concentrated solutions and of human erythrocyte cytoplasm determined from NMR measurement of molecular correlation times. The dependence of viscosity on cell volume.

    PubMed

    Endre, Z H; Kuchel, P W

    1986-08-01

    Metabolically active human erythrocytes were incubated with [alpha-13C]glycine which led to the specific enrichment of intracellular glutathione. The cells were then studied using 13C-NMR in which the longitudinal relaxation times (T1) and nuclear Overhauser enhancements of the free glycine and glutathione were measured. The T1 values of labelled glycine were also determined in various-concentration solutions of bovine serum albumin and glycerol and also of the natural abundance 13C of glycerol in glycerol solutions. From the T1 estimates the rotational correlation time (tau r) was calculated using a formula based on a model of an isotropic spherical rotor or that of a symmetrical ellipsoidal rotor; for glycine the differences in estimates of tau r obtained using the two models were not significant. From the correlation times and by use of the Stokes-Einstein equations viscosity and translational diffusion coefficients were calculated; thus comment can be made on the likelihood of diffusion control of certain enzyme-catalysed reactions in the erythrocyte. Bulk viscosities of the erythrocyte cytoplasm and the above-mentioned solutions were measured using Ostwald capillary viscometry. Large differences existed between the latter viscosity estimates and those based upon NMR-T1 measurements. We derived an equation from the theory of the viscosity of concentrated solutions which contains two phenomenological interaction parameters, a 'shape' factor and a 'volume' factor; it was fitted to data relating to the concentration dependence of viscosity measured by both methods. We showed, by using the equation and interaction-parameter estimates for a particular probe molecule in a particular solution, that it was possible to correlate NMR viscosity and bulk viscosity; in other words, given an estimate of the bulk viscosity, it was possible to calculate the NMR 'micro' viscosity or vice versa. However, the values of the interaction parameters depend upon the relative sizes of

  11. Absolute nutrient concentration measurements in cell culture media: (1)H q-NMR spectra and data to compare the efficiency of pH-controlled protein precipitation versus CPMG or post-processing filtering approaches.

    PubMed

    Goldoni, Luca; Beringhelli, Tiziana; Rocchia, Walter; Realini, Natalia; Piomelli, Daniele

    2016-09-01

    The NMR spectra and data reported in this article refer to the research article titled "A simple and accurate protocol for absolute polar metabolite quantification in cell cultures using q-NMR" [1]. We provide the (1)H q-NMR spectra of cell culture media (DMEM) after removal of serum proteins, which show the different efficiency of various precipitating solvents, the solvent/DMEM ratios, and pH of the solution. We compare the data of the absolute nutrient concentrations, measured by PULCON external standard method, before and after precipitation of serum proteins and those obtained using CPMG (Carr-Purcell-Meiboom-Gill) sequence or applying post-processing filtering algorithms to remove, from the (1)H q-NMR spectra, the proteins signal contribution. For each of these approaches, the percent error in the absolute value of every measurement for all the nutrients is also plotted as accuracy assessment. PMID:27331118

  12. A multiple pulse zero crossing NMR technique, and its application to F-19 chemical shift measurements in solids

    NASA Technical Reports Server (NTRS)

    Burum, D. P.; Elleman, D. D.; Rhim, W.-K.

    1978-01-01

    A simple multiple-pulse 'zero crossing technique' for accurately determining the first moment of a solid-state NMR spectrum is introduced. This technique was applied to obtain the F-19 chemical shift versus pressure curves up to 5 kbar for single crystals of CaF2 (0.29 + or - 0.02 ppm/kbar) and BaF2 (0.62 + or - 0.05 ppm/kbar). Results at ambient temperature and pressure are also reported for a number of other fluorine compounds. Because of its high data rate, this technique is potentially several orders of magnitude more sensitive than similar CW methods.

  13. Fabrication of nanoelectrodes for neurophysiology: cathodic electrophoretic paint insulation and focused ion beam milling

    PubMed Central

    Qiao, Yi; Chen, Jie; Guo, Xiaoli; Cantrell, Donald; Ruoff, Rodney; Troy, John

    2005-01-01

    The fabrication and characterization of tungsten nanoelectrodes insulated with cathodic electrophoretic paint is described together with their application within the field of neurophysiology. The tip of a 127 μm diameter tungsten wire was etched down to less than 100 nm and then insulated with cathodic electrophoretic paint. Focused ion beam (FIB) polishing was employed to remove the insulation at the electrode’s apex, leaving a nanoscale sized conductive tip of 100–1000 nm. The nanoelectrodes were examined by scanning electron microscopy (SEM) and their electrochemical properties characterized by steady state linear sweep voltammetry. Electrode impedance at 1 kHz was measured too. The ability of a 700 nm tipped electrode to record well-isolated action potentials extracellularly from single visual neurons in vivo was demonstrated. Such electrodes have the potential to open new populations of neurons to study. PMID:16467926

  14. Electrophoretic Mobility of Poly(acrylic acid)-Coated Alumina Particles

    SciTech Connect

    Bhosale, Prasad S.; Chun, Jaehun; Berg, John C.

    2011-06-01

    The effect of poly (acrylic acid) (PAA) adsorption on the electrokinetic behavior of alumina dispersions under high pH conditions was investigated as a function of polymer concentration and molecular weight as well as the presence, concentration and ion type of background electrolyte. Systems of this type are relevant to nuclear waste treatment, in which PAA is known to be an effective rheology modifier. The presence of all but the lowest molecular weight PAA studied (1800) led to decreases in dynamic electrophoretic mobility at low polymer concentrations, attributable to bridging flocculation, as verified by measurements of particle size distribution. Bridging effects increased with polymer molecular weight, and decreased with polymer concentration. Increases in background electrolyte concentration enhanced dynamic electrophoretic mobility as the polymer layers were compressed and bridging was reduced. Such enhancements were reduced as the cation was changed from Na+ to K+ to Cs+.

  15. Fabrication of nanoelectrodes for neurophysiology: cathodic electrophoretic paint insulation and focused ion beam milling

    NASA Astrophysics Data System (ADS)

    Qiao, Yi; Chen, Jie; Guo, Xiaoli; Cantrell, Donald; Ruoff, Rodney; Troy, John

    2005-09-01

    The fabrication and characterization of tungsten nanoelectrodes insulated with cathodic electrophoretic paint is described together with their application within the field of neurophysiology. The tip of a 127 µm diameter tungsten wire was etched down to less than 100 nm and then insulated with cathodic electrophoretic paint. Focused ion beam (FIB) polishing was employed to remove the insulation at the electrode's apex, leaving a nanoscale sized conductive tip of 100-1000 nm. The nanoelectrodes were examined by scanning electron microscopy (SEM) and their electrochemical properties characterized by steady state linear sweep voltammetry. Electrode impedance at 1 kHz was measured too. The ability of a 700 nm tipped electrode to record well-isolated action potentials extracellularly from single visual neurons in vivo was demonstrated. Such electrodes have the potential to open new populations of neurons to study.

  16. In situ measurement of magnesium carbonate formation from CO2 using static high-pressure and -temperature 13C NMR.

    PubMed

    Surface, J Andrew; Skemer, Philip; Hayes, Sophia E; Conradi, Mark S

    2013-01-01

    We explore a new in situ NMR spectroscopy method that possesses the ability to monitor the chemical evolution of supercritical CO(2) in relevant conditions for geological CO(2) sequestration. As a model, we use the fast reaction of the mineral brucite, Mg(OH)(2), with supercritical CO(2) (88 bar) in aqueous conditions at 80 °C. The in situ conversion of CO(2) into metastable and stable carbonates is observed throughout the reaction. After more than 58 h of reaction, the sample was depressurized and analyzed using in situ Raman spectroscopy, where the laser was focused on the undisturbed products through the glass reaction tube. Postreaction, ex situ analysis was performed on the extracted and dried products using Raman spectroscopy, powder X-ray diffraction, and magic-angle spinning (1)H-decoupled (13)C NMR. These separate methods of analysis confirmed a spatial dependence of products, possibly caused by a gradient of reactant availability, pH, and/or a reaction mechanism that involves first forming hydroxy-hydrated (basic, hydrated) carbonates that convert to the end-product, anhydrous magnesite. This carbonation reaction illustrates the importance of static (unmixed) reaction systems at sequestration-like conditions. PMID:22676479

  17. Design and characterization of a calixarene inclusion compound for calibration of long-range carbon-fluorine distance measurements by solid-state NMR

    PubMed Central

    Fowler, Daniel J.; Khalifah, Peter G.; Thompson, Lynmarie K.

    2010-01-01

    An inexpensive, easily synthesized calixarene:fluorotoluene host:guest inclusion complex has been designed for optimization and calibration of solid-state NMR measurements of carbon-fluorine distances using Rotational Echo DOuble Resonance (REDOR). Complexation of the fluorotoluene with the calixarene host separates the molecules such that simple two-spin behavior is observed for one site with a 4.08 Å carbon-fluorine distance. Fluorotoluene dynamics within the calixarene matrix causes motional averaging of the dipolar couplings that make it possible to easily optimize REDOR experiments and test their accuracy for relatively long distance measurements (> 6.6 Å). This provides a new tool for accurate REDOR measurements of long carbon-fluorine distances, which have important applications in the characterization of fluorine-containing drugs, proteins, and polymers. PMID:20822943

  18. Column-coupling strategies for multidimensional electrophoretic separation techniques.

    PubMed

    Kler, Pablo A; Sydes, Daniel; Huhn, Carolin

    2015-01-01

    Multidimensional electrophoretic separations represent one of the most common strategies for dealing with the analysis of complex samples. In recent years we have been witnessing the explosive growth of separation techniques for the analysis of complex samples in applications ranging from life sciences to industry. In this sense, electrophoretic separations offer several strategic advantages such as excellent separation efficiency, different methods with a broad range of separation mechanisms, and low liquid consumption generating less waste effluents and lower costs per analysis, among others. Despite their impressive separation efficiency, multidimensional electrophoretic separations present some drawbacks that have delayed their extensive use: the volumes of the columns, and consequently of the injected sample, are significantly smaller compared to other analytical techniques, thus the coupling interfaces between two separations components must be very efficient in terms of providing geometrical precision with low dead volume. Likewise, very sensitive detection systems are required. Additionally, in electrophoretic separation techniques, the surface properties of the columns play a fundamental role for electroosmosis as well as the unwanted adsorption of proteins or other complex biomolecules. In this sense the requirements for an efficient coupling for electrophoretic separation techniques involve several aspects related to microfluidics and physicochemical interactions of the electrolyte solutions and the solid capillary walls. It is interesting to see how these multidimensional electrophoretic separation techniques have been used jointly with different detection techniques, for intermediate detection as well as for final identification and quantification, particularly important in the case of mass spectrometry. In this work we present a critical review about the different strategies for coupling two or more electrophoretic separation techniques and the

  19. Fully-Automated High-Throughput NMR System for Screening of Haploid Kernels of Maize (Corn) by Measurement of Oil Content

    PubMed Central

    Xu, Xiaoping; Huang, Qingming; Chen, Shanshan; Yang, Peiqiang; Chen, Shaojiang; Song, Yiqiao

    2016-01-01

    One of the modern crop breeding techniques uses doubled haploid plants that contain an identical pair of chromosomes in order to accelerate the breeding process. Rapid haploid identification method is critical for large-scale selections of double haploids. The conventional methods based on the color of the endosperm and embryo seeds are slow, manual and prone to error. On the other hand, there exists a significant difference between diploid and haploid seeds generated by high oil inducer, which makes it possible to use oil content to identify the haploid. This paper describes a fully-automated high-throughput NMR screening system for maize haploid kernel identification. The system is comprised of a sampler unit to select a single kernel to feed for measurement of NMR and weight, and a kernel sorter to distribute the kernel according to the measurement result. Tests of the system show a consistent accuracy of 94% with an average screening time of 4 seconds per kernel. Field test result is described and the directions for future improvement are discussed. PMID:27454427

  20. Fully-Automated High-Throughput NMR System for Screening of Haploid Kernels of Maize (Corn) by Measurement of Oil Content.

    PubMed

    Wang, Hongzhi; Liu, Jin; Xu, Xiaoping; Huang, Qingming; Chen, Shanshan; Yang, Peiqiang; Chen, Shaojiang; Song, Yiqiao

    2016-01-01

    One of the modern crop breeding techniques uses doubled haploid plants that contain an identical pair of chromosomes in order to accelerate the breeding process. Rapid haploid identification method is critical for large-scale selections of double haploids. The conventional methods based on the color of the endosperm and embryo seeds are slow, manual and prone to error. On the other hand, there exists a significant difference between diploid and haploid seeds generated by high oil inducer, which makes it possible to use oil content to identify the haploid. This paper describes a fully-automated high-throughput NMR screening system for maize haploid kernel identification. The system is comprised of a sampler unit to select a single kernel to feed for measurement of NMR and weight, and a kernel sorter to distribute the kernel according to the measurement result. Tests of the system show a consistent accuracy of 94% with an average screening time of 4 seconds per kernel. Field test result is described and the directions for future improvement are discussed. PMID:27454427

  1. Electrophoretic nanotechnology of composite electrodes for electrochemical supercapacitors.

    PubMed

    Su, Y; Zhitomirsky, I

    2013-02-14

    The electrophoretic deposition (EPD) method has been developed for the fabrication of MnO(2)-multiwalled carbon nanotube (MWCNT) films for application in electrochemical supercapacitors (ESs). For MWCNT applications, which depend on electrical conductivity, it is challenging to achieve dispersion and EPD of pristine MWCNT and avoid defects due to chemical treatment or functionalization. An important finding was the possibility of efficient dispersion and controlled EPD of MWCNT using calconcarboxylic acid (CCA). Moreover, the use of CCA allowed efficient dispersion of MnO(2) in concentrated suspensions and EPD of MnO(2) films. The comparison of the experimental data for chromotrope FB (CFB) and CCA and chemical structures of the molecules provided insight into the mechanism of CCA adsorption on MnO(2). The fabrication of stable suspensions of MnO(2) nanoparticles containing MWCNT, and controlled codeposition of both materials is a crucial aspect in the EPD of composites. The new approach was based on the use of CCA as a charging and dispersing agent for EPD of MnO(2) nanoparticles and MWCNT. The deposition yield measurements at various experimental conditions and Fourier transform infrared spectroscopy data, coupled with results of electron microscopy, thermogravimetric, and differential thermal analysis provided evidence of the formation of MnO(2)-MWCNT composites. The electrochemical testing results and impedance spectroscopy data showed good capacitive behavior of the composite films and the beneficial effect of MWCNTs. PMID:22662969

  2. Formation of κ-carrageenan-gelatin polyelectrolyte complexes studied by (1)H NMR, UV spectroscopy and kinematic viscosity measurements.

    PubMed

    Voron'ko, Nicolay G; Derkach, Svetlana R; Vovk, Mikhail A; Tolstoy, Peter M

    2016-10-20

    The intermolecular interactions between an anionic polysaccharide from the red algae κ-carrageenan and a gelatin polypeptide, forming stoichiometric polysaccharide-polypeptide (bio)polyelectrolyte complexes in the aqueous phase, were examined. The major method of investigation was high-resolution (1)H NMR spectroscopy. Additional data were obtained by UV absorption spectroscopy, light scattering dispersion and capillary viscometry. Experimental data were interpreted in terms of the changing roles of electrostatic interactions, hydrophobic interactions and hydrogen bonds when κ-carrageenan-gelatin complexes are formed. At high temperatures, when biopolymer macromolecules in solution are in the state of random coil, hydrophobic interactions make a major contribution to complex stabilization. At the temperature of gelatin's coil→helix conformational transition and at lower temperatures, electrostatic interactions and hydrogen bonds play a defining role in complex formation. A proposed model of the κ-carrageenan-gelatin complex is discussed. PMID:27474666

  3. Mapping membrane protein backbone dynamics: a comparison of site-directed spin labeling with NMR 15N-relaxation measurements.

    PubMed

    Lo, Ryan H; Kroncke, Brett M; Solomon, Tsega L; Columbus, Linda

    2014-10-01

    The ability to detect nanosecond backbone dynamics with site-directed spin labeling (SDSL) in soluble proteins has been well established. However, for membrane proteins, the nitroxide appears to have more interactions with the protein surface, potentially hindering the sensitivity to backbone motions. To determine whether membrane protein backbone dynamics could be mapped with SDSL, a nitroxide was introduced at 55 independent sites in a model polytopic membrane protein, TM0026. Electron paramagnetic resonance spectral parameters were compared with NMR (15)N-relaxation data. Sequential scans revealed backbone dynamics with the same trends observed for the R1 relaxation rate, suggesting that nitroxide dynamics remain coupled to the backbone on membrane proteins. PMID:25296323

  4. Electrophoretic characterization of insulin growth factor (IGF-1) functionalized magnetic nanoparticles.

    PubMed

    Viota, Julián L; Rudzka, Katarzyna; Trueba, Ángel; Torres-Aleman, Ignacio; Delgado, Ángel V

    2011-05-17

    The synthesis of composite nanoparticles consisting of a magnetite core coated with a layer of the hormone insulin growth factor 1 (IGF-1) is described. The adsorption of the hormone in the different formulations is first studied by electrophoretic mobility measurements as a function of pH, ionic strength, and time. Because of the permeable character expected for both citrate and IGF-1 coatings surrounding the magnetite cores, an appropriate analysis of their electrophoretic mobility must be addressed. Recent developments of electrokinetic theories for particles covered by soft surface layers have rendered possible the evaluation of the softness degree from raw electrophoretic mobility data. In the present contribution, the data are quantitatively analyzed based on the theoretical model of the electrokinetics of soft particles. As a result, information is obtained on both the thickness and the charge density of the surrounding layer. It is shown that IGF-1 adsorbs onto the surface of citrate-coated magnetite nanoparticles, and adsorption is confirmed by dot-blot analysis. In addition, it is also demonstrated that the external layer of IGF-1 exerts a shielding effect on the surface charge of citrate-magnetite particles, as suggested by the mobility reduction upon contacting the particles with the hormone. Aging effects are demonstrated, providing an electrokinetic fingerprint of changes in adsorbed protein configuration with time. PMID:21506536

  5. Finger-powered electrophoretic transport of discrete droplets for portable digital microfluidics.

    PubMed

    Peng, Cheng; Wang, Yide; Sungtaek Ju, Y

    2016-07-01

    We report a finger-powered digital microfluidic device based on the electrophoretic transport of discrete droplets (EPD). An array of piezoelectric elements is connected in parallel to metal electrodes immersed in dielectric fluids. When deflected in a controlled sequence via human finger power, the piezoelectric elements charge and actuate droplets across each electrode pair through electrophoretic force. Successful droplet transportation requires the piezoelectric elements to provide both sufficient charge and voltage pulse duration. We quantify these requirements using numerical models to predict the electrical charges induced on the droplets and the corresponding electrophoretic forces. The models are experimentally validated by comparing the predicted and measured droplet translational velocities. We successfully demonstrated transport and merging of aqueous droplets over a range of droplet radii (0.6-0.9 mm). We further showed direct manipulation of body fluids, including droplets of saliva and urine, using our finger-powered EPD device. To facilitate practical implementation of multistep assays based on the approach, a hand/finger-rotated drum system with a programmable pattern of protrusions is designed to induce deflections of multiple piezoelectric elements and demonstrate programmable fluidic functions. An electrode-to-piezoelectric element connection scheme to minimize the number of piezoelectric elements necessary for a sequence of microfluidic functions is also explored. The present work establishes an engineering foundation to enable design and implementation of finger-powered portable EPD microfluidic devices. PMID:27292054

  6. AN ELECTROPHORETIC STUDY OF A STREPTOCOCCAL PROTEINASE AND ITS PRECURSOR

    PubMed Central

    Shedlovsky, Theodore; Elliott, S. D.

    1951-01-01

    An electrophoretic study of crystalline preparations of a streptococcal proteinase and its precursor established their isoelectric points at pH values of 8.42 and 7.35 respectively (ionic strength 0.10). Preparations of the proteinase appeared to be electrophoretically homogeneous over a pH range of 5 to 8.5. Precursor preparations contained a relatively low concentration of the active enzyme visible as a separate peak in electrophoretic patterns of sufficiently concentrated solutions. Autocatalytic conversion of precursor to active enzyme was complete and resulted in a corresponding change in the electrophoretic pattern. Treatment of precursor preparations with trypsin produced incomplete conversion to the active enzyme and resulted in the formation of a modified precursor protein. This differed from the parent substance in electrophoretic mobility and in susceptibility to trypsin, but resembled it in immunological specificity and, as previously shown, in susceptibility to conversion to active enzyme by autocatalysis. Serological reactions of precursor and active enzyme components withdrawn from the cell after electrophoresis are described. It appears that the precursor protein may have two antigenic groups, one specific, the other shared by the active enzyme which behaves as a single antigen. PMID:14888818

  7. Electrophoretic mobility of silica particles in a mixture of toluene and ethanol at different particle concentrations.

    PubMed

    Medrano, M; Pérez, A T; Lobry, L; Peters, F

    2009-10-20

    In this paper we present measurements of the electrophoretic mobility of colloidal particles by using heterodyne detection of light scattering. The measurements have been made up to concentrations of 5.4% silica nanoparticles, with a diameter on the order of 80 nm, in a mixture of 70% toluene and 30% ethanol. To make possible the measurements at these concentrations, the liquid mixture is chosen so as to match the index of refraction of the particles, thus resulting in a transparent suspension. PMID:19754057

  8. Hyphenated low-field NMR techniques: combining NMR with NIR, GPC/SEC and rheometry.

    PubMed

    Räntzsch, Volker; Wilhelm, Manfred; Guthausen, Gisela

    2016-06-01

    Hyphenated low-field NMR techniques are promising characterization methods for online process analytics and comprehensive offline studies of soft materials. By combining different analytical methods with low-field NMR, information on chemical and physical properties can be correlated with molecular dynamics and complementary chemical information. In this review, we present three hyphenated low-field NMR techniques: a combination of near-infrared spectroscopy and time-domain NMR (TD-NMR) relaxometry, online (1) H-NMR spectroscopy measured directly after size exclusion chromatographic (SEC, also known as GPC) separation and a combination of rheometry and TD-NMR relaxometry for highly viscous materials. Case studies are reviewed that underline the possibilities and challenges of the different hyphenated low-field NMR methods. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25854997

  9. Volovik effect and Fermi-liquid behavior in the s-wave superconductor CaPd2As2: As75 NMR-NQR measurements

    DOE PAGESBeta

    Ding, Q. -P.; Wiecki, P.; Anand, V. K.; Sangeetha, N. S.; Lee, Y.; Johnston, D. C.; Furukawa, Y.

    2016-04-07

    The electronic and magnetic properties of the collapsed-tetragonal CaPd2As2 superconductor (SC) with a transition temperature of 1.27 K have been investigated by 75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. The temperature (T) dependence of the nuclear spin lattice relaxation rates (1/T1) and the Knight shifts indicate the absence of magnetic correlations in the normal state. In the SC state, 1/T1 measured by 75As NQR shows a clear Hebel-Slichter (HS) peak just below Tc and decreases exponentially at lower T, confirming a conventional s-wave SC. Additionally, the Volovik effect, also known as the Doppler shift effect, hasmore » been clearly evidenced by the observation of the suppression of the HS peak with applied magnetic field.« less

  10. Volovik effect and Fermi-liquid behavior in the s -wave superconductor CaPd2As2: 75As NMR-NQR measurements

    NASA Astrophysics Data System (ADS)

    Ding, Q.-P.; Wiecki, P.; Anand, V. K.; Sangeetha, N. S.; Lee, Y.; Johnston, D. C.; Furukawa, Y.

    2016-04-01

    The electronic and magnetic properties of the collapsed-tetragonal CaPd2As2 superconductor (SC) with a transition temperature of 1.27 K have been investigated by 75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. The temperature (T ) dependence of the nuclear spin lattice relaxation rates (1 /T1) and the Knight shifts indicate the absence of magnetic correlations in the normal state. In the SC state, 1 /T1 measured by 75As NQR shows a clear Hebel-Slichter (HS) peak just below Tc and decreases exponentially at lower T , confirming a conventional s -wave SC. In addition, the Volovik effect, also known as the Doppler shift effect, has been clearly evidenced by the observation of the suppression of the HS peak with applied magnetic field.

  11. Formation of p-cresol:piperazine complex in solution monitored by spin-lattice relaxation times and pulsed field gradient NMR diffusion measurements

    NASA Astrophysics Data System (ADS)

    de Carvalho, Erika Martins; Velloso, Marcia Helena Rodrigues; Tinoco, Luzineide Wanderley; Figueroa-Villar, José Daniel

    2003-10-01

    A study of the nature of the anthelmintic p-cresol:piperazine complex in chloroform solution has been conducted using different NMR techniques: self-diffusion coefficients using DOSY; NOE, NULL, and double-selective T1 measurements to determine inter-molecular distances; and selective and non-selective T1 measurements to determine correlation times. The experimental results in solution and CP-MAS were compared to literature X-ray diffraction data using molecular modeling. It was shown that the p-cresol:piperazine complex exists in solution in a very similar manner as it does in the solid state, with one p-cresol molecule hydrogen bonded through the hydroxyl hydrogen to each nitrogen atom of piperazine. The close correspondence between the X-ray diffraction data and the inter-proton distances obtained by NULL and double selective excitation techniques indicate that those methodologies can be used to determine inter-molecular distances in solution.

  12. 33S NMR cryogenic probe for taurine detection

    NASA Astrophysics Data System (ADS)

    Hobo, Fumio; Takahashi, Masato; Maeda, Hideaki

    2009-03-01

    With the goal of a S33 nuclear magnetic resonance (NMR) probe applicable to in vivo NMR on taurine-biological samples, we have developed the S33 NMR cryogenic probe, which is applicable to taurine solutions. The NMR sensitivity gain relative to a conventional broadband probe is as large as 3.5. This work suggests that improvements in the preamplifier could allow NMR measurements on 100 μM taurine solutions, which is the level of sensitivity necessary for biological samples.

  13. Studies of vanadium-phosphorus-oxygen selective oxidation catalysts by sup 31 P and sup 51 V NMR spin-echo and volume susceptibility measurements

    SciTech Connect

    Li, Juan.

    1991-10-01

    The purpose of this work is to characterize the vanadium-phosphorous oxide (V-P-O) catalysts for the selective oxidation of n-butane and 1-butene to maleic anhydride. The utility of solid state nuclear magnetic resonance as an analytical tool in this investigation lies in its sensitivity to the electronic environment surrounding the phosphorous and vanadium nuclei, and proximity of paramagnetic species. Spin-echo mapping NMR of {sup 31}p and {sup 51}v and volume magnetic susceptibility measurements were used as local microscopic probes of the presence of V{sup 5+}, V{sup 4+}, V{sup 3+} species in the model compounds: {beta}-VOPO{sub 4}, {beta}-VOPO{sub 4} treated with n-butane/1-butene, (VO){sub 2}P{sub 2}O{sub 7} treated with n-butane/1-butene; and industrial catalysts with P/V (phosphorus to vanadium) ratio of 0.9, 1.0 and 1.1, before and after treatment with n-butane and 1-butene. The NMR spectra provide a picture of how the oxidation states of vanadium are distributed in these catalysts. 73 refs., 32 figs., 8 tabs.

  14. Solid state 31P MAS NMR spectroscopy and conductivity measurements on NbOPO4 and H3PO4 composite materials

    NASA Astrophysics Data System (ADS)

    Risskov Sørensen, Daniel; Nielsen, Ulla Gro; Skou, Eivind M.

    2014-11-01

    A systematic study of composite powders of niobium oxide phosphate (NbOPO4) and phosphoric acid (H3PO4) has been performed in order to characterize the material's ability to perform as an electrolyte material in medium temperature fuel cells and electrolyzers. Powders of H3PO4 contents between 13.1 and 74.2 M% were produced and characterized with powder X-ray diffraction, 31P MAS NMR and impedance spectroscopy. NMR revealed that a significant degree of dehydration and vaporization of H3PO4 takes place above 200 °C, and increases with temperature. At 500 °C the NbOPO4 and H3PO4 has reacted to form niobium pyrophosphate (Nb2P4O15). Impedance spectroscopy showed an increase in conductivity with increasing acid concentration, whereas the conductivity decreased slightly with increasing temperature. The highest conductivity measured was 2.5·10-3 S/cm for a sample containing 74.2 M% of H3PO4. Lastly, it was shown that NbOPO4 has no significant conductivity of its own.

  15. Electrophoretic interactions and aggregation of colloidal biological particles

    NASA Technical Reports Server (NTRS)

    Davis, Robert H.; Nichols, Scott C.; Loewenberg, Michael; Todd, Paul

    1994-01-01

    The separation of cells or particles from solution has traditionally been accomplished with centrifuges or by sedimentation; however, many particles have specific densities close to unity, making buoyancy-driven motion slow or negligible, but most cells and particles carry surface charges, making them ideal for electrophoretic separation. Both buoyancy-driven and electrophoretic separation may be influenced by hydrodynamic interactions and aggregation of neighboring particles. Aggregation by electrophoresis was analyzed for two non-Brownian particles with different zeta potentials and thin double layers migrating through a viscous fluid. The results indicate that the initial rate of electrophoretically-driven aggregation may exceed that of buoyancy-driven aggregation, even under conditions in which buoyancy-driven relative motion of noninteracting particles is dominant.

  16. Electrophoretic approach to the biochemical systematics of gammarids

    NASA Astrophysics Data System (ADS)

    Bulnheim, H.-P.; Scholl, A.

    1981-12-01

    By utilizing the techniques for electrophoretic separation of proteins by vertical starch gels, the biochemical systematics of 10 Gammaridae species obtained from marine, brackish and freshwater habitats was studied. They included Chaetogammarus marinus, Gammarus zaddachi, G. salinus, G. oceanicus, G. tigrinus, G. chevreuxi, G. locusta, G. duebeni duebeni, G. d. celticus, G. pulex pulex, and G. fossarum. For comparison of electrophoretic mobilities selected enzymes (phosphoglucose isomerase, glutamate oxalacetate transaminase, arginine phosphokinase, hexokinase, leucine amino peptidase, mannose 6-phosphate isomerase) were assayed. They were used as diagnostic characters in terms of electrophoretic identities or diversities of most frequent alleles at polymorphic gene loci. These criteria could be applied to estimate intrageneric enzymic variation and degrees of genetic relatedness between the crustacean amphipod species under consideration, thereby complementing traditional morphological classification.

  17. NMR Relaxation and Petrophysical Properties

    NASA Astrophysics Data System (ADS)

    Fleury, Marc

    2011-03-01

    NMR relaxation is routinely used in the field of geosciences to give basic petrophysical properties such as porosity, pore size distribution, saturation etc. In this tutorial, we focus on the pore size distribution deduced from NMR. We recall the basic principle used in the interpretation of the NMR signal and compare the results with other standard petrophysical techniques such as mercury pore size distribution, BET specific surface measurements, thin section visualizations. The NMR pore size distribution is a unique information available on water saturated porous media and can give similar results as MICP in certain situations. The scaling of NMR relaxation time distribution (s) into pore sizes (μm) requires the knowledge of the surface relaxivity (μm/s) and we recommend using specific surface measurements as an independent determination of solid surface areas. With usual surface relaxivities, the NMR technique can explore length-scales starting from nano-meters and ending around 100 μm. Finally, we will introduce briefly recent techniques sensitive to the pore to pore diffusional exchange, providing new information on the connectivity of the pore network, but showing another possibility of discrepancy in the determination of pore size distribution with standard techniques.

  18. Theory of electrophoretic separations. I - Formulation of a mathematical model

    NASA Technical Reports Server (NTRS)

    Saville, D. A.; Palusinski, O. A.

    1986-01-01

    A generally applicable model of electrophoretic processes is presented. The model describes the chemical reactions, treating the chemical processes as reactions at equilibrium and accounting for convection, conservation, diffusion, and electromigration of individual species as well as the relation between charge and potential. Conservation relations are described and simplified, taking advantage of the speed of the chemical reactions as compared to the transport processes to adapt the model to the electrophoretic processes involving weak electrolytes. As an application example, isotachophoresis in a one-dimensional column is considered in detail.

  19. High charged red pigment nanoparticles for electrophoretic displays

    NASA Astrophysics Data System (ADS)

    Hou, Xin-Yan; Bian, Shu-Guang; Chen, Jian-Feng; Le, Yuan

    2012-12-01

    Organic pigment permanent red F2R nanoparticles were prepared via surface modification to improve the surface charge and dispersion ability in organic medium. Their large surface chargeability is confirmed by ζ-potential value of -49.8 mV. The prepared particles exhibited average size of 105 nm and showed very narrow distribution with polydispersity index of 0.068. The sedimentation ratio of the prepared particles in tetrachloroethylene was less than 5% within 12 days. The electrophoretic inks consisting of the prepared red particles with white particles as contrast showed good electrophoretic display, its refresh time was 200 ms.

  20. Electrophoretic Transport of Biomolecules through Carbon Nanotube Membranes

    PubMed Central

    Sun, Xinghua; Su, Xin; Wu, Ji; Hinds, Bruce J.

    2013-01-01

    Electrophoretic transport of proteins across electrochemically oxidized multi-walled carbon nanotube (MWCNT) membranes has been investigated. Small charged protein, lysozyme, was successfully pumped across MWCNT membranes by electric field while rejecting larger bovine serum albumin (BSA). Transport of the lysozome was reduced by a factor of about 30 in comparison to bulk mobility and consistent with prediction for hindered transport. Mobilities between 0.33-1.4×10-9 m2/V-s were observed and are approximately 10 fold faster than comparable ordered nanoporous membranes and are consistent with continuum models. For mixtures of BSA and lysozyme, complete rejection of BSA is seen with electrophoretic separations PMID:21338104

  1. Metastatic Melanoma Induced Metabolic Changes in C57BL/6J Mouse Stomach Measured by 1H NMR Spectroscopy

    DOE PAGESBeta

    Hu, M; Wang, Xiliang

    2014-12-05

    Melanoma is a malignant tumor of melanocytes with high capability of invasion and rapid metastasis to other organs. Malignant melanoma is the most common metastatic malignancy found in gastrointestinal tract (GI). To the best of our knowledge, previous studies of melanoma in gastrointestinal tract are all clinical case reports. In this work, 1H NMR-based metabolomics approach is used to investigate the metabolite profiles differences of stomach tissue extracts of metastatic B16-F10 melanoma in C57BL/6J mouse and search for specific metabolite biomarker candidates. Principal Component Analysis (PCA), an unsupervised multivariate data analysis method, is used to detect possible outliers, while Orthogonalmore » Projection to Latent Structure (OPLS), a supervised multivariate data analysis method, is employed to evaluate important metabolites responsible for discriminating the control and the melanoma groups. Both PCA and OPLS results reveal that the melanoma group can be well separated from its control group. Among the 50 identified metabolites, it is found that the concentrations of 19 metabolites are statistically and significantly changed with the levels of O-phosphocholine and hypoxanthine down-regulated while the levels of isoleucine, leucine, valine, isobutyrate, threonine, cadaverine, alanine, glutamate, glutamine, methionine, citrate, asparagine, tryptophan, glycine, serine, uracil, and formate up-regulated in the melanoma group. These significantly changed metabolites are associated with multiple biological pathways and may be potential biomarkers for metastatic melanoma in stomach.« less

  2. Metastatic Melanoma Induced Metabolic Changes in C57BL/6J Mouse Stomach Measured by 1H NMR Spectroscopy

    SciTech Connect

    Hu, M; Wang, Xiliang

    2014-12-05

    Melanoma is a malignant tumor of melanocytes with high capability of invasion and rapid metastasis to other organs. Malignant melanoma is the most common metastatic malignancy found in gastrointestinal tract (GI). To the best of our knowledge, previous studies of melanoma in gastrointestinal tract are all clinical case reports. In this work, 1H NMR-based metabolomics approach is used to investigate the metabolite profiles differences of stomach tissue extracts of metastatic B16-F10 melanoma in C57BL/6J mouse and search for specific metabolite biomarker candidates. Principal Component Analysis (PCA), an unsupervised multivariate data analysis method, is used to detect possible outliers, while Orthogonal Projection to Latent Structure (OPLS), a supervised multivariate data analysis method, is employed to evaluate important metabolites responsible for discriminating the control and the melanoma groups. Both PCA and OPLS results reveal that the melanoma group can be well separated from its control group. Among the 50 identified metabolites, it is found that the concentrations of 19 metabolites are statistically and significantly changed with the levels of O-phosphocholine and hypoxanthine down-regulated while the levels of isoleucine, leucine, valine, isobutyrate, threonine, cadaverine, alanine, glutamate, glutamine, methionine, citrate, asparagine, tryptophan, glycine, serine, uracil, and formate up-regulated in the melanoma group. These significantly changed metabolites are associated with multiple biological pathways and may be potential biomarkers for metastatic melanoma in stomach.

  3. Analysis of internal motions of interleukin-13 variant associated with severe bronchial asthma using {sup 15}N NMR relaxation measurements

    SciTech Connect

    Yoshida, Yuichiro; Ohkuri, Takatoshi; Takeda, Chika; Kuroki, Ryota; Izuhara, Kenji; Imoto, Taiji; Ueda, Tadashi . E-mail: ueda@phar.kyushu-u.ac.jp

    2007-06-22

    The single nucleotide polymorphism interleukin-13 (IL-13) R110Q is associated with severe bronchial asthma because its lower affinity leads to the augmentation of local IL-13 concentration, resulting in an increase in the signal transduction via IL-13R. Since the mutation site does not directly bind to IL-13R{alpha}2, we carried out NMR relaxation analyses of the wild-type IL-13 and IL-13-R110Q in order to examine whether the R110Q mutation affects the internal motions in IL-13 molecules. The results showed that the internal motion in the micro- to millisecond time scale on helix D, which is suggested to be important for the interaction between IL-13 and IL-13R{alpha}2, is increased in IL-13-R110Q compared with that in the wild-type IL-13. It therefore appears that the difference in the internal motions on helix D between the wild-type IL-13 and IL-13-R110Q may be involved in their affinity differences with IL-13R{alpha}2.

  4. Metastatic Melanoma Induced Metabolic Changes in C57BL/6J Mouse Stomach Measured by 1H NMR Spectroscopy

    PubMed Central

    Wang, X; Hu, M; Liu, M; Hu, JZ

    2015-01-01

    Melanoma is a malignant tumor of melanocytes with high capability of invasion and rapid metastasis to other organs. Malignant melanoma is the most common metastatic malignancy found in Gastrointestinal Tract (GI). In this work, the 1H NMR-based metabolomics approach is used to investigate the metabolite profile differences of stomach tissue extracts of metastatic B16-F10 melanoma and control groups in C57BL/6J mouse and to search for specific metabolite biomarker candidates. Principal Component Analysis (PCA), an unsupervised multivariate data analysis method, is used to detect possible outliers, while Orthogonal Projection to Latent Structure (OPLS), a supervised multivariate data analysis method, is employed to evaluate important metabolites responsible for discriminating the control and the melanoma groups. Both PCA and OPLS results reveal that the melanoma group can be well separated from its control group. Among the 50 identified metabolites, it is found that the concentrations of 19 metabolites are significantly changed with the levels of O-phosphocholine and hypoxanthine down-regulated while the levels of isoleucine, leucine, valine, isobutyrate, threonine, cadaverine, alanine, glutamate, glutamine, methionine, citrate, asparagine, tryptophan, glycine, serine, uracil, and formate up-regulated in the melanoma group. These significantly changed metabolites are associated with multiple biological pathways and may be potential biomarkers for metastatic melanoma in stomach. PMID:26246958

  5. Sucrose, glucose, and fructose extraction in aqueous carrot root extracts prepared at different temperatures by means of direct NMR measurements.

    PubMed

    Cazor, Anne; Deborde, Catherine; Moing, Annick; Rolin, Dominique; This, Hervé

    2006-06-28

    Solutions obtained by heating carrot roots in water (stocks) are widely used in the food industry, but little information is available regarding the metabolites (intermediates and products of metabolism) found in the stock. The effect of treatment temperature and duration on the sugar composition of stocks was investigated directly by quantitative (1)H NMR spectroscopy, to understand the extraction mechanism when processing at 100 degrees C. Stocks prepared at three different temperatures (50, 75, and 100 degrees C) were investigated for up to 36 h. Three sugars (sucrose, glucose, and fructose) were detected and quantified. The concentrations of these three sugars reached a maximum after 9 h when the temperature of treatment was 50 or 75 degrees C. At 100 degrees C, the sucrose concentration reached a maximum after 3 h, whereas the concentration of glucose and fructose was still increasing at that time. Comparison of the kinetic composition of these carrot stocks with that of model sugar solutions leads to the proposal that the changes in stock composition result from sugar diffusion, sucrose hydrolysis, and hydroxymethylfurfural (HMF) formation. PMID:16787015

  6. Direct measurement of agonist binding to genetically engineered peptides of the acetylcholine receptor by selective T sub 1 NMR relaxation

    SciTech Connect

    Fraenkel, Y.; Navon, G. ); Aronheim, A.; Gershoni, J.M. )

    1990-03-13

    Interactions of four ligands of the nicotinic acetylcholine receptor with genetically engineered peptides have been studied by NMR. A recombinant cholinergic binding site was prepared as a fusion protein between a truncated form of the bacterial protein trpE and a peptide corresponding to the sequence {alpha}184-200 from the Torpedo californica receptor. This construct binds {alpha}-bungarotoxin while the trpE protein alone does not, and thus serves as a negative control. In this study agonist binding to {alpha}184-200 is demonstrated by monitoring the T{sub 1} relaxation of the ligand's protons in the presence and absence of the recombinant binding site. This binding is specific as it can be competed with {alpha}-bungarotoxin. Quantitative analyses of such competitions yielded the concentration of binding sites, which corresponded to 3.3% and 16.5% of the total protein, for partially purified and affinity-purified {alpha}184-200 constructs, respectively. The K{sub D} values for the binding of acetylcholine, nicotine, d-tubocurarine, and gallamine to the affinity-purified construct were 1.4, 1.4, 0.20, and 0.21 mM, respectively, while K{sub D}'s with the nontoxin binding protein were all above 10 mM. Thus, this is a direct demonstration that the toxin binding domain {alpha}184-200 may comprise a major component of the cholinergic agonist site.

  7. Large NMR signals and polarization asymmetries.

    SciTech Connect

    Penttila, S. I.

    1998-11-25

    A large modulation in the series Q-meter can lead to nonlinear NMR signals and asymmetric polarization values. With a careful circuit analysis the nonlinearity can be estimated and corrections to polarization can be determined as a function of the strength of the modulation. We describe the recent LAMPF polarized proton target experiment, its NMR measurement and corrections to the measured polarizations.

  8. NMR Imaging: Instrumentation and Techniques

    NASA Astrophysics Data System (ADS)

    Tingle, Jeremy Mark

    Available from UMI in association with The British Library. This thesis presents three original contributions to the field of Nuclear Magnetic Resonance (NMR): the experimental framework and analysis for the measurement of a new imaging parameter to describe perfusion; the measurement and analysis of magnetic field inhomogeneity and a practical correction system for their reduction; a novel system for the synchronous control of NMR experiments based on the microprogrammed concept. The thesis begins with an introduction to the theory of NMR. The application of NMR to imaging is also introduced with emphasis on the techniques which developed into those in common use today. Inaccurate determination of the traditional NMR parameters (T_1 and T_2 and the molecular diffusion coefficient) can be caused by non-diffusive fluid movement within the sample. The experimental basis for determining a new imaging parameter --the Perfusion coefficient--is presented. This provides a measure of forced isotropic fluid motion through an organ or tissue. The instrumentation required for conducting NMR experiments is described in order to introduce the contribution made in this area during this research: A sequence controller. The controller is based on the concept of microprogramming and enables completely synchronous output of 128 bits of data. The software for the generation and storage of control data and the regulation of the data to provide experimental control is microcomputer based. It affords precise and accurate regulation of the magnetic field gradients, the rf synthesizer and the spectrometer for spectroscopic and imaging applications. Fundamental to the science of NMR is the presence of a magnetic field. A detailed study of the analysis of magnetic field inhomogeneity in terms of spherical harmonics is presented. The field of a whole body imaging system with poor inhomogeneity was measured and analyzed to determine and describe the components of the inhomogeneity. Finally a

  9. Liquid phase separation of proteins based on electrophoretic effects in an electrospray setup during sample introduction into a gas-phase electrophoretic mobility molecular analyzer (CE–GEMMA/CE–ES–DMA)

    PubMed Central

    Weiss, Victor U.; Kerul, Lukas; Kallinger, Peter; Szymanski, Wladyslaw W.; Marchetti-Deschmann, Martina; Allmaier, Günter

    2014-01-01

    Nanoparticle characterization is gaining importance in food technology, biotechnology, medicine, and pharmaceutical industry. An instrument to determine particle electrophoretic mobility (EM) diameters in the single-digit to double-digit nanometer range receiving increased attention is the gas-phase electrophoretic mobility molecular analyzer (GEMMA) separating electrophoretically single charged analytes in the gas-phase at ambient pressure. A fused-silica capillary is used for analyte transfer to the gas-phase by means of a nano electrospray (ES) unit. The potential of this capillary to separate analytes electrophoretically in the liquid phase due to different mobilities is, at measurement conditions recommended by the manufacturer, eliminated due to elevated pressure applied for sample introduction. Measurements are carried out upon constant feeding of analytes to the system. Under these conditions, aggregate formation is observed for samples including high amounts of non-volatile components or complex samples. This makes the EM determination of individual species sometimes difficult, if not impossible. With the current study we demonstrate that liquid phase electrophoretic separation of proteins (as exemplary analytes) occurs in the capillary (capillary zone electrophoresis, CE) of the nano ES unit of the GEMMA. This finding was consecutively applied for on-line desalting allowing EM diameter determination of analytes despite a high salt concentration within samples. The present study is to our knowledge the first report on the use of the GEMMA to determine EM diameters of analytes solubilized in the ES incompatible electrolyte solutions by the intended use of electrophoresis (in the liquid phase) during sample delivery. Results demonstrate the proof of concept of such an approach and additionally illustrate the high potential of a future on-line coupling of a capillary electrophoresis to a GEMMA instrument. PMID:25109866

  10. Spin-singlet formation in the geometrically frustrated spinel oxide AlV2O4 : V51 and A27l NMR measurements

    NASA Astrophysics Data System (ADS)

    Shimizu, Yasuhiro; Tanaka, Moe; Itoh, Masayuki; Katsufuji, Takuro

    2008-10-01

    We report V51 and A27l NMR studies of the spin-frustrated spinel oxide AlV2O4 in a temperature range from 850 to 2 K across a structural phase transition at 700 K. Knight shifts and nuclear spin-lattice relaxation rates at the V and Al sites show that the local spin susceptibility at two V sites diminishes at low temperatures in the insulating state, giving direct evidence for the spin-singlet formation. In addition to the singlet spins, one of the two Al sites probes paramagnetic spins with the Curie-Weiss behavior and the spin-glass transition. The results demonstrate coexistence of the spin-singlet cluster and the nearly free spins, anticipated from a theoretical model and the bulk magnetic-susceptibility measurements.

  11. /sup 31/P NMR saturation-transfer measurements in Saccharomyces cerevisiae: characterization of phosphate exchange reactions by iodoacetate and antimycin A inhibition

    SciTech Connect

    Campbell-Burk, S.L.; Jones, K.A.; Shulman, R.G.

    1987-11-17

    /sup 31/P nuclear magnetic resonance (NMR) saturation-transfer (ST) techniques have been used to measure steady-state flows through phosphate-adenosine 5'-triphosphate (ATP) exchange reactions in glucose-grown derepressed yeast. The results have revealed that the reactions catalyzed by glyceraldehyde-3-phosphate dehydrogenase/phosphoglycerate kinase (GAPDH/PGK) and by the mitochondrial ATPase contribute to the observed ST. Contributions from these reactions were evaluated by performing ST studies under various metabolic conditions in the presence and absence of either iodoacetate, a specific inhibitor of GAPDH, or the respiratory chain inhibitor antimycin A. Intracellular phosphate (P/sub i/) longitudinal relaxation times were determined by performing inversion recovery experiments during steady-state ATP/sub lambda/ saturation and were used in combination with ST data to determine P/sub i/ consumption rates. /sup 13/C NMR and O/sub 2/ electrode measurements were also conducted to monitor changes in rates of glucose consumption and O/sub 2/ consumption, respectively, under the various metabolic conditions examined. The results suggest that GAPDH/PGK-catalyzed P/sub i/-ATP exchange is responsible for antimycin-resistant saturation transfer observed in anaerobic and aerobic glucose-fed yeast. Kinetics through GAPDH/PGK were found to depend on metabolic conditions. The coupled system appears to operate in a unidirectional manner during anaerobic glucose metabolism and bidirectionally when the cells are respiring on exogenously supplied ethanol. Additionally, mitochondrial ATPase activity appears to be responsible for the transfer observed in iodoacetate-treated aerobic cells supplied with either glucose or ethanol, with synthesis of ATP occurring unidirectionally.

  12. Cell electrophoretic characterization of peripheral blood lymphocyte subpopulations enriched by rosette formation, from normal individuals and CLL patients.

    PubMed

    Rychly, J; Babusíková, O; Koníková, E; Anders, O

    1984-01-01

    Peripheral blood lymphocytes from healthy subjects and patients with chronic lymphatic leukemia (CLL) were isolated and their subpopulations enriched through formation of spontaneous rosettes with sheep or mouse red blood cells, respectively. Electrophoretic measurements were performed in unseparated as well as in fractionated cell populations. Normal blood lymphocytes showed two clearly distinguishable populations of different electrophoretic mobilities. After separation by SRBC rosette formation the rosette-forming cells could be identified as high mobility cells. CLL lymphocytes showed in most cases an unimodally distributed cytopherogram, the mean electrophoretic mobility being intermediate between the low and high mobility cells of control persons. After separation through mouse erythrocytes rosette formation these cells contained two cell fractions differing in their electrophoretic mobility: a fraction of slower mouse rosette-forming cells and a fraction of the non-MRFC which contained mainly cells of higher mobility that could be identified as enriched T cells. These both fractions showed unimodal distributions. This study shows that CLL lymphocyte subpopulations can be further characterized by surface charge density. PMID:6700796

  13. Soils, Pores, and NMR

    NASA Astrophysics Data System (ADS)

    Pohlmeier, Andreas; Haber-Pohlmeier, Sabina; Haber, Agnes; Sucre, Oscar; Stingaciu, Laura; Stapf, Siegfried; Blümich, Bernhard

    2010-05-01

    Within Cluster A, Partial Project A1, the pore space exploration by means of Nuclear Magnetic Resonance (NMR) plays a central role. NMR is especially convenient since it probes directly the state and dynamics of the substance of interest: water. First, NMR is applied as relaxometry, where the degree of saturation but also the pore geometry controls the NMR signature of natural porous systems. Examples are presented where soil samples from the Selhausen, Merzenhausen (silt loams), and Kaldenkirchen (sandy loam) test sites are investigated by means of Fast Field Cycling Relaxometry at different degrees of saturation. From the change of the relaxation time distributions with decreasing water content and by comparison with conventional water retention curves we conclude that the fraction of immobile water is characterized by T1 < 5 ms. Moreover, the dependence of the relaxation rate on magnetic field strength allows the identification of 2D diffusion at the interfaces as the mechanism which governs the relaxation process (Pohlmeier et al. 2009). T2 relaxation curves are frequently measured for the rapid characterization of soils by means of the CPMG echo train. Basically, they contain the same information about the pore systems like T1 curves, since mostly the overall relaxation is dominated by surface relaxivity and the surface/volume ratio of the pores. However, one must be aware that T2 relaxation is additionally affected by diffusion in internal gradients, and this can be overcome by using sufficiently short echo times and low magnetic fields (Stingaciu et al. 2009). Second, the logic continuation of conventional relaxation measurements is the 2-dimensional experiment, where prior to the final detection of the CPMG echo train an encoding period is applied. This can be T1-encoding by an inversion pulse, or T2 encoding by a sequence of 90 and 180° pulses. During the following evolution time the separately encoded signals can mix and this reveals information about

  14. Electrophoretic separation of human kidney cells at zero gravity

    NASA Technical Reports Server (NTRS)

    Barlow, G. H.; Lazer, S. L.; Rueter, A.; Allen, R. E.

    1977-01-01

    Electrophoretic isolation of cells results in a loss of resolution power caused by the sedimentation of the cells in the media. The results of an experiment to extract urokinase from human embryos during the Apollo Soyuz mission are presented and discussed.

  15. Electrophoretic separation of kidney and pituitary cells on STS-8

    NASA Astrophysics Data System (ADS)

    Morrison, D. R.; Nachtwey, D. S.; Barlow, G. H.; Cleveland, C.; Lanham, J. W.; Farrington, M. A.; Hatfield, J. M.; Hymer, W. C.; Todd, P.; Wilfinger, W.; Grindeland, R.; Lewis, M. L.

    A Continuous Flow Electrophoresis System (CFES) was used on Space Shuttle flight STS-8 to separate specific secretory cells from suspensions of cultured primary human embryonic kidney cells and rat pituitary cells. The objectives were to isolate the subfractions of kidney cells that produce the largest amounts of urokinase (plasminogen activator), and to isolate the subfractions of rat pituitary cells that secrete growth hormone, prolactin, and other hormones. Kidney cells were separated into more than 32 fractions in each of two electrophoretic runs. Electrophoretic mobility distributions in flight experiments were spread more than the ground controls. Multiple assay methods confirmed that all cultured kidney cell fractions produced some urokinase, and five to six fractions produced significantly more urokinase than the other fractions. Several fractions also produced tissue plasminogen activator. The pituitary cells were separated into 48 fractions in each of the two electrophoretic runs, and the amounts of growth hormone (GH) and prolactin (PRL) released into the medium for each cell fraction were determined. Cell fractions were grouped into eight mobility classes and immunocytochemically assayed for the presence of GH, PRL, ACTH, LH, TSH, and FSH. The patterns of hormone distribution indicate that the specialized cells producing GH and PRL are isolatable due to the differences in electrophoretic mobilities.

  16. Antiplasmin activity of electrophoretically separated human serum fractions

    PubMed Central

    Mann, R. D.; Cotton, Susan; Jackson, D.

    1966-01-01

    The antiplasmin which migrates electrophoretically with the alpha2 globulins preponderates in effect over that of the alpha1 migrating antiplasmin. This preponderance persists at physiological pH value in vitro and the significance of this finding is discussed. No evidence has been obtained of the existence of anti-urokinase activity in antiplasmin-free serum fractions. PMID:4160096

  17. Controlled method of reducing electrophoretic mobility of various substances

    NASA Technical Reports Server (NTRS)

    Vanalstine, James M. (Inventor)

    1989-01-01

    A method of reducing electrophoretic mobility of macromolecules, particles, cells, and the like is provided. The method comprises interacting the particles or cells with a polymer-linked affinity compound composed of: a hydrophilic neutral polymer such as polyethylene glycol, and an affinity component consisting of a hydrophobic compound such as a fatty acid ester, an immunocompound such as an antibody or active fragment thereof or simular macromolecule, or other ligands. The reduction of electrophoretic mobility achieved is directly proportional to the concentration of the polymer-linked affinity compound employed, and the mobility reduction obtainable is up to 100 percent for particular particles and cells. The present invention is advantageous in that analytical electrophoretic separation can not be achieved for macromolecules, particles, and cells whose native surface charge structure had prevented them from being separated by normal electrophoretic means. Depending on the affinity component utilized, separation can be achieved on the basis of specific/irreversible, specific/reversible, semi-specific/reversible, relatively nonspecific/reversible, or relatively nonspecific/irreversible ligand-substance interactions. The present method is also advantageous in that it can be used in a variety of standard laboratory electrophoresis equipment.

  18. Monodisperse light color nanoparticle ink toward chromatic electrophoretic displays

    NASA Astrophysics Data System (ADS)

    Peng, Bo; Li, Yue; Li, Jian; Bi, Lei; Lu, Haipeng; Xie, Jianliang; Ren, Xiangling; Cao, Yonghai; Wang, Ning; Meng, Xianwei; Deng, Longjiang; Guo, Zhanhu

    2016-05-01

    The facile synthesis of nanoparticles for precise image control and fast response of chromatic electrophoretic displays (EPDs) is a challenge. Herein, we report a general method to prepare pink, blue, and yellow nanoparticles with low density and a tunable size of 230-310 nm. The monodispersity is down to 0.02 and surface charges are up to 666e. Importantly, our work highlights the feasibility of chromatic nanoparticles as cost-effective candidates for electrophoretic displays.The facile synthesis of nanoparticles for precise image control and fast response of chromatic electrophoretic displays (EPDs) is a challenge. Herein, we report a general method to prepare pink, blue, and yellow nanoparticles with low density and a tunable size of 230-310 nm. The monodispersity is down to 0.02 and surface charges are up to 666e. Importantly, our work highlights the feasibility of chromatic nanoparticles as cost-effective candidates for electrophoretic displays. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02524b

  19. 21 CFR 864.7440 - Electrophoretic hemoglobin analysis system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Electrophoretic hemoglobin analysis system. 864.7440 Section 864.7440 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  20. 21 CFR 864.7440 - Electrophoretic hemoglobin analysis system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Electrophoretic hemoglobin analysis system. 864.7440 Section 864.7440 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  1. 21 CFR 864.7440 - Electrophoretic hemoglobin analysis system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Electrophoretic hemoglobin analysis system. 864.7440 Section 864.7440 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  2. 21 CFR 864.7440 - Electrophoretic hemoglobin analysis system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Electrophoretic hemoglobin analysis system. 864.7440 Section 864.7440 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages §...

  3. Solid state {sup 31}P MAS NMR spectroscopy and conductivity measurements on NbOPO{sub 4} and H{sub 3}PO{sub 4} composite materials

    SciTech Connect

    Risskov Sørensen, Daniel; Nielsen, Ulla Gro; Skou, Eivind M.

    2014-11-15

    A systematic study of composite powders of niobium oxide phosphate (NbOPO{sub 4}) and phosphoric acid (H{sub 3}PO{sub 4}) has been performed in order to characterize the material's ability to perform as an electrolyte material in medium temperature fuel cells and electrolyzers. Powders of H{sub 3}PO{sub 4} contents between 13.1 and 74.2 M% were produced and characterized with powder X-ray diffraction, {sup 31}P MAS NMR and impedance spectroscopy. NMR revealed that a significant degree of dehydration and vaporization of H{sub 3}PO{sub 4} takes place above 200 °C, and increases with temperature. At 500 °C the NbOPO{sub 4} and H{sub 3}PO{sub 4} has reacted to form niobium pyrophosphate (Nb{sub 2}P{sub 4}O{sub 15}). Impedance spectroscopy showed an increase in conductivity with increasing acid concentration, whereas the conductivity decreased slightly with increasing temperature. The highest conductivity measured was 2.5·10{sup −3} S/cm for a sample containing 74.2 M% of H{sub 3}PO{sub 4}. Lastly, it was shown that NbOPO{sub 4} has no significant conductivity of its own. - Graphical abstract: Conductivity of NbOPO{sub 4}/H{sub 3}PO{sub 4} composites as a function of equivalent P{sub 2}O{sub 5} content. The conductivity is insignificant for pure NbOPO{sub 4}. - Highlights: • Composites have been made from NbOPO{sub 4} and H{sub 3}PO{sub 4}. • The composites composition has been investigated with solid state NMR. • The composites have shown clear signs of acid dehydration upon heating. • The conductivity of the composites increases for increasing acid content. • NbOPO{sub 4} has no significant conductivity of its own.

  4. Electrophoretic Separation of Single Particles Using Nanoscale Thermoplastic Columns.

    PubMed

    Weerakoon-Ratnayake, Kumuditha M; Uba, Franklin I; Oliver-Calixte, Nyoté J; Soper, Steven A

    2016-04-01

    Phenomena associated with microscale electrophoresis separations cannot, in many cases, be applied to the nanoscale. Thus, understanding the electrophoretic characteristics associated with the nanoscale will help formulate relevant strategies that can optimize the performance of separations carried out on columns with at least one dimension below 150 nm. Electric double layer (EDL) overlap, diffusion, and adsorption/desorption properties and/or dielectrophoretic effects giving rise to stick/slip motion are some of the processes that can play a role in determining the efficiency of nanoscale electrophoretic separations. We investigated the performance characteristics of electrophoretic separations carried out in nanoslits fabricated in poly(methyl methacrylate), PMMA, devices. Silver nanoparticles (AgNPs) were used as the model system with tracking of their transport via dark field microscopy and localized surface plasmon resonance. AgNPs capped with citrate groups and the negatively charged PMMA walls (induced by O2 plasma modification of the nanoslit walls) enabled separations that were not apparent when these particles were electrophoresed in microscale columns. The separation of AgNPs based on their size without the need for buffer additives using PMMA nanoslit devices is demonstrated herein. Operational parameters such as the electric field strength, nanoslit dimensions, and buffer composition were evaluated as to their effects on the electrophoretic performance, both in terms of efficiency (plate numbers) and resolution. Electrophoretic separations performed at high electric field strengths (>200 V/cm) resulted in higher plate numbers compared to lower fields due to the absence of stick/slip motion at the higher electric field strengths. Indeed, 60 nm AgNPs could be separated from 100 nm particles in free solution using nanoscale electrophoresis with 100 μm long columns. PMID:26963496

  5. Comparing nanostructured hydroxyapatite coating on AZ91 alloy samples via sol-gel and electrophoretic deposition for biomedical applications.

    PubMed

    Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

    2014-12-01

    Magnesium is one of the most critical elements in hard tissues regeneration and therefore causes speeding up the restoration of harmed bones, while high deterioration rate of magnesium in body fluid restricts it to be used as biodegradable implants. Alloying magnesium with some relatively nobler metals such as aluminium, zinc, rare earth elements, magnesium-bioceramics composites, and surface modification techniques are some of the routes to control magnesium corrosion rate. In this study AZ91 magnesium alloy had been coated by nanostructured hydroxyapatite via sol-gel dip coating and electrophoretical methods to survey the final barricade properties of the obtained coatings. In order to perform electrophoretic coating, powders were prepared by sol-gel method, and then the powders deposited on substrates utilizing direct current electricity. Zeta potentials of the electrophoresis suspensions were measured to determine a best mode for good quality coatings. Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM) were used to confirm nanoscale dimension, and the uniformity of the nanostructured hydroxyapatite coating, respectively. Fourier Transform-Infrared and X-ray diffraction analysis were utilized for functional group and phase structure evaluation of the prepared coatings, correspondingly. Electrochemical corrosion tests were performed in SBF at 37±1 (°)C which revealed considerable increase in corrosion protection resistivity and corrosion current density for electrophoretic coated specimens versus sol-gel coated specimens. Results showed that both sol-gel and electrophoretical techniques seem to be suitable to coat magnesium alloys for biomedical applications but electrophoretic coating technique is a better choice due to the more homogeneity and more crystalline structure of the coating. PMID:25095258

  6. Measurement of the Isotopic Ratio of [to the tenth power]B/[to the eleventh power]B in NaBH[subscript 4] by [to the first power]H NMR

    ERIC Educational Resources Information Center

    Zanger, Murray; Moyna, Guillermo

    2005-01-01

    A study uses nuclear magnetic resonance (NMR) spectroscopy in a novel way to determine the isotopic ration between [to the tenth power]B and [to the eleventh power]B in sodium borohydride (NaBH4). The experiment provides an unusual and relatively simple means for undergraduate chemistry students to accurately measure the distribution of the two…

  7. Erratum for the Appendix of "Measuring small compartment dimensions by probing diffusion dynamics via Non-uniform Oscillating-Gradient Spin-Echo (NOGSE) NMR" [J. Magn. Reson. 247 (2014) 110

    NASA Astrophysics Data System (ADS)

    Shemesh, Noam; Álvarez, Gonzalo A.; Frydman, Lucio

    2015-05-01

    This corrects a typo of Eq. (A4) in the Erratum [J. Magn. Reson. 247 (2014) 110] for the Appendix of "Measuring small compartment dimensions by probing diffusion dynamics via Non-uniform Oscillating-Gradient Spin-Echo (NOGSE) NMR". The Erratum should have read as follow:

  8. An Inversion Recovery NMR Kinetics Experiment

    ERIC Educational Resources Information Center

    Williams, Travis J.; Kershaw, Allan D.; Li, Vincent; Wu, Xinping

    2011-01-01

    A convenient laboratory experiment is described in which NMR magnetization transfer by inversion recovery is used to measure the kinetics and thermochemistry of amide bond rotation. The experiment utilizes Varian spectrometers with the VNMRJ 2.3 software, but can be easily adapted to any NMR platform. The procedures and sample data sets in this…

  9. A SENSITIVE NMR THERMOMETER FOR MULTINUCLEI FT NMR

    EPA Science Inventory

    A pernicious problem in multinuclei FT NMR is accurate measurement of sample temperature. This arises from several factors including widespread use of high-power decoupling, large sample tubes (with potentially large temperature gradients across the sample volume), and lack of su...

  10. NMR analysis of biodiesel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodiesel is usually analyzed by the various methods called for in standards such as ASTM D6751 and EN 14214. Nuclear magnetic resonance (NMR) is not one of these methods. However, NMR, with 1H-NMR commonly applied, can be useful in a variety of applications related to biodiesel. These include monit...

  11. A 300 MHz and 600 MHz proton NMR study of a 12 base pair restriction fragment: investigation of structure by relaxation measurements.

    PubMed Central

    Early, T A; Kearns, D R; Hillen, W; Wells, R D

    1980-01-01

    The 1H NMR spectrum of a 12 base pair DNA restriction fragment has been measured at 300 and 600 MHz and resonances from over 70 protons are individually resolved. Relaxation rate measurements have been carried out at 300 MHz and compared with the theoretical predictions obtained using an isotropic rigid rotor model with coordinates derived from a Dreiding model of DNA. The model gives results that are in excellent agreement with experiment for most protons when a 7 nsec rotational correlation time is used, although agreement is improved for certain base protons by using a shorter correlation time for the sugar group, or by increasing the sugar-base interproton distances. A comparison of non-selective and selective spin-lattice relaxation rates for carbon bound protons indicates that there is extensive spin diffusion even in this short DNA fragment. Examination of the spin-spin relaxation rates for the same type of proton on different base pairs reveals little sequence effect on conformation. PMID:6258152

  12. Correlating steric hydration forces with water dynamics through surface force and diffusion NMR measurements in a lipid–DMSO–H2O system

    PubMed Central

    Schrader, Alex M.; Donaldson, Stephen H.; Song, Jinsuk; Cheng, Chi-Yuan; Lee, Dong Woog; Han, Songi; Israelachvili, Jacob N.

    2015-01-01

    Dimethyl sulfoxide (DMSO) is a common solvent and biological additive possessing well-known utility in cellular cryoprotection and lipid membrane permeabilization, but the governing mechanisms at membrane interfaces remain poorly understood. Many studies have focused on DMSO–lipid interactions and the subsequent effects on membrane-phase behavior, but explanations often rely on qualitative notions of DMSO-induced dehydration of lipid head groups. In this work, surface forces measurements between gel-phase dipalmitoylphosphatidylcholine membranes in DMSO–water mixtures quantify the hydration- and solvation-length scales with angstrom resolution as a function of DMSO concentration from 0 mol% to 20 mol%. DMSO causes a drastic decrease in the range of the steric hydration repulsion, leading to an increase in adhesion at a much-reduced intermembrane distance. Pulsed field gradient NMR of the phosphatidylcholine (PC) head group analogs, dimethyl phosphate and tetramethylammonium ions, shows that the ion hydrodynamic radius decreases with increasing DMSO concentration up to 10 mol% DMSO. The complementary measurements indicate that, at concentrations below 10 mol%, the primary effect of DMSO is to decrease the solvated volume of the PC head group and that, from 10 mol% to 20 mol%, DMSO acts to gradually collapse head groups down onto the surface and suppress their thermal motion. This work shows a connection between surface forces, head group conformation and dynamics, and surface water diffusion, with important implications for soft matter and colloidal systems. PMID:26261313

  13. 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%.

  14. Studies on Effects of Impurity Doping and NMR Measurements of La 1111 and/or Nd 1111 Fe-Pnictide Superconductors

    NASA Astrophysics Data System (ADS)

    Sato, Masatoshi; Kobayashi, Yoshiaki; Lee, Sang Chul; Takahashi, Hidefumi; Satomi, Erika; Miura, Yoko

    2010-01-01

    Measurements of the electrical resistivity ρ, Hall coefficient RH, thermoelectric power S, and the electronic specific heat coefficient γ have been carried out for samples of LnFe1-yMyAsO1-xFx (Ln=La, Nd; M=Co, Mn; x=0.11) obtained by doping M atoms into the superconducting LnFeAsO1-xFx (Ln 1111) system. The NMR longitudinal relaxation rate 1/T1 has also been measured for samples of LaFe1-yCoyAsO1-xFx with various x values. Co atoms doped into the superconducting LnFeAsO1-xFx are nonmagnetic, and the rate of Tc-suppression |dTc/dx| by Co atoms has been found to be too small to be explained by the pair-breaking effect expected for the S± superconducting symmetry proposed as the most probable symmetry for the system. This result throws a serious doubt on whether the symmetry is realized in the system. Instead of the pair breaking, two mechanisms of Tc suppression by the doped impurities have been found: One is the electron localization, which appears when the sheet resistance R\\square exceeds h/4e2=6.45 kΩ, and the other is the disappearance (or reduction in the area) of the hole Fermi surfaces around the Γ point in the reciprocal space. The latter mechanism has been observed when the number of electrons increases with increasing Co doping level and the system changes from an “anomalous metal” to an ordinary one. Regarding the two distinct T dependences of the NMR longitudinal relaxation rate 1/T1 of LaFeAsO1-xFx, (1/T1\\propto T6 reported by our group in the T region from Tc to ˜0.4 Tc for samples with the highest Tc values with varying x, and 1/T1\\propto T2.5--3.0 observed by many groups in almost the entire T region studied below Tc), we discuss the origin of such a difference, and show that, at least, the T2.5--3.0-like dependence of 1/T1 cannot be considered as the experimental evidence for the S± symmetry of Δ.

  15. Electrophoretic transport of biomolecules across liquid-liquid interfaces.

    PubMed

    Hahn, Thomas; Münchow, Götz; Hardt, Steffen

    2011-05-11

    The mass transfer resistance of a liquid-liquid interface in an aqueous two-phase system composed of poly(ethylene glycol) and dextran is investigated. Different types of proteins and DNA stained with fluorescent dyes serve as probes to study the transport processes close to the interface. A microfluidic device is employed to enable the electrophoretic transport of biomolecules from one phase to another. The results obtained for proteins can be explained solely via the different electrophoretic mobilities and different affinities of the molecules to the two phases, without any indications of a significant mass transfer resistance of the liquid-liquid interface. By contrast, DNA molecules adsorb to the interface and only desorb under an increased electric field strength. The desorption process carries the signature of a thermally activated escape from a metastable state, as reflected in the exponential decay of the fluorescence intensity at the interface as a function of time. PMID:21508474

  16. [A new electrophoretic method for coating metalceramic elements with opaque].

    PubMed

    Weber, H

    1979-05-01

    A new, electrophoretical method of coating dental alloys (Au or Ni-Cr) with opaque is described for the first time. The comparison of this method with the known wet brush technique shows that bubbles or voids might occur at the interface between metal and opaque when applying the first ceramic layer manually whereas the electrophoretical one generates a thin and dense layer of porcelain being free of voids within the adherence zone. Those bubbles are considered to be inherent with the brush technique. The author suggests to galvanize dental alloys particularly noble metals in order to suppress any anodic reactions. General advantage for the bond due to galvanization are expected no matter how the opaque was applied. PMID:380960

  17. Capillary Electrophoretic Technologies for Single Cell Metabolomics

    ERIC Educational Resources Information Center

    Lapainis, Theodore E.

    2009-01-01

    Understanding the functioning of the brain is hindered by a lack of knowledge of the full complement of neurotransmitters and neuromodulatory compounds. Single cell measurements aid in the discovery of neurotransmitters used by small subsets of neurons that would be diluted below detection limits or masked by ubiquitous compounds when working with…

  18. Metabolic flux and metabolic network analysis of Penicillium chrysogenum using 2D [13C, 1H] COSY NMR measurements and cumulative bondomer simulation.

    PubMed

    van Winden, Wouter A; van Gulik, Walter M; Schipper, Dick; Verheijen, Peter J T; Krabben, Preben; Vinke, Jacobus L; Heijnen, Joseph J

    2003-07-01

    At present two alternative methods are available for analyzing the fluxes in a metabolic network: (1) combining measurements of net conversion rates with a set of metabolite balances including the cofactor balances, or (2) leaving out the cofactor balances and fitting the resulting free fluxes to measured (13)C-labeling data. In this study these two approaches are applied to the fluxes in the glycolysis and pentose phosphate pathway of Penicillium chrysogenum growing on either ammonia or nitrate as the nitrogen source, which is expected to give different pentose phosphate pathway fluxes. The presented flux analyses are based on extensive sets of 2D [(13)C, (1)H] COSY data. A new concept is applied for simulation of this type of (13)C-labeling data: cumulative bondomer modeling. The outcomes of the (13)C-labeling based flux analysis substantially differ from those of the pure metabolite balancing approach. The fluxes that are determined using (13)C-labeling data are shown to be highly dependent on the chosen metabolic network. Extending the traditional nonoxidative pentose phosphate pathway with additional transketolase and transaldolase reactions, extending the glycolysis with a fructose 6-phosphate aldolase/dihydroxyacetone kinase reaction sequence or adding a phosphoenolpyruvate carboxykinase reaction to the model considerably improves the fit of the measured and the simulated NMR data. The results obtained using the extended version of the nonoxidative pentose phosphate pathway model show that the transketolase and transaldolase reactions need not be assumed reversible to get a good fit of the (13)C-labeling data. Strict statistical testing of the outcomes of (13)C-labeling based flux analysis using realistic measurement errors is demonstrated to be of prime importance for verifying the assumed metabolic model. PMID:12740935

  19. An electrophoretic study of urinary protein in the rat.

    PubMed

    SELLERS, A L; ROBERTS, S; RASK, I; SMITH, S; MARMORSTON, J; GOODMAN, H C

    1952-05-01

    The nature of the proteins present in the urine of the normal rat has been investigated by electrophoretic analysis and by fractional precipitation of these proteins by ammonium sulfate. Components similar to serum alpha- and beta-globulin constitute the major portion of the urinary protein in both male and female rats. Following the intraperitoneal injection of renin, a massive proteinuria occurs. The proteins excreted are similar in proportion and electric mobility to those of normal rat serum. PMID:14927799

  20. AN ELECTROPHORETIC STUDY OF URINARY PROTEIN IN THE RAT

    PubMed Central

    Sellers, Alvin L.; Roberts, Sidney; Rask, Irene; Smith, Stephen; Marmorston, Jessie; Goodman, Howard C.

    1952-01-01

    The nature of the proteins present in the urine of the normal rat has been investigated by electrophoretic analysis and by fractional precipitation of these proteins by ammonium sulfate. Components similar to serum α- and β-globulin constitute the major portion of the urinary protein in both male and female rats. Following the intraperitoneal injection of renin, a massive proteinuria occurs. The proteins excreted are similar in proportion and electric mobility to those of normal rat serum. PMID:14927799

  1. Electrophoretic mobilities and migrating analytes: Part 1: Relationships.

    PubMed

    Cross, Reginald F; Wong, Margaret G

    2002-01-01

    The molecular radii (r) of a series of peptides have been determined by molecular modeling. With these data, it is shown that electrophoretic mobility (mu(ep)) is proportional to 1/r2, and that the dependence presented in textbooks (mu(ep) infinity 1/r) is wrong. Use of the approximately equivalent, mass-based Offord equation is discussed, and other relevant considerations are presented. PMID:12546161

  2. Measurement of hetero-nuclear distances using a symmetry-based pulse sequence in solid-state NMR.

    PubMed

    Chen, Lei; Wang, Qiang; Hu, Bingwen; Lafon, Olivier; Trébosc, Julien; Deng, Feng; Amoureux, Jean-Paul

    2010-08-28

    A Symmetry-based Resonance-Echo DOuble-Resonance (S-REDOR) method is proposed for measuring hetero-nuclear dipolar couplings between two different spin-1/2 nuclei, under fast magic-angle spinning. The hetero-nuclear dipolar couplings are restored by employing the SR4 sequence, which requires the rf-field strength to be only twice the spinning frequency. The S-REDOR experiment is extended to S-RESPDOR (Symmetry-based Resonance-Echo Saturation-Pulse DOuble-Resonance) for determining dipolar coupling between a spin-1/2 nucleus (e.g.(13)C) and (14)N. It is demonstrated that S-REDOR and S-RESPDOR methods suppress efficiently the homo-nuclear dipolar interaction of the irradiated nucleus and benefit from high robustness to the rf-field inhomogeneity, chemical shielding and dipolar truncation. Therefore, these methods allow the measurement of (13)C/(14,15)N distances, with (13)C observation, in uniformly (13)C-labeled samples. Furthermore, we provide analytical solutions for the S-REDOR and S-RESPDOR dephasing curves. These solutions facilitate the measurement of hetero-nuclear distances from experimental data. PMID:20577687

  3. Urokinase production by electrophoretically separated cultured human embryonic kidney cells

    NASA Technical Reports Server (NTRS)

    Kunze, M. E.; Plank, L. D.; Giranda, V.; Sedor, K.; Todd, P. W.

    1985-01-01

    Urokinase is a plasminogen activator found in urine. Relatively pure preparations have been tested in Europe, Japan and the United States for the treatment of deep vein thrombosis and other dangerous blood clots. Human embryonic kidney cell cultures have been found to produce urokinase at much higher concentrations, but less than 5% of the cells in typical cultures are producers. Since human diploid cells become senescent in culture the selection of clones derived from single cells will not provide enough material to be useful, so a bulk purification method is needed for the isolation of urokinase producing cell populations. Preparative cell electrophoresis was chosen as the method, since evidence exists that human embryonic cell cultures are richly heterogeneous with respect to electrophoretic mobility, and preliminary electrophoretic separations on the Apollo-Soyuz space flight produced cell populations that were rich in urokinase production. Similarly, erythropoietin is useful in the treatment of certain anemias and is a kidney cell duct, and electrophoretically enriched cell populations producing this product have been reported. Thus, there is a clear need for diploid human cells that produce these products, and there is evidence that such cells should be separable by free-flow cell electrophoresis.

  4. Insights into the molecular architecture of a peptide nanotube using FTIR and solid-state NMR spectroscopic measurements on an aligned sample.

    PubMed

    Middleton, David A; Madine, Jillian; Castelletto, Valeria; Hamley, Ian W

    2013-09-27

    Queuing up: Molecular orientation within macroscopically aligned nanotubes of the peptide AAAAAAK can be studied by solid-state NMR and IR spectroscopy. Line shape analysis of the NMR spectra indicates that the peptide N-H bonds are tilted 65-70° relative to the nanotube long axis. Re-evaluation of earlier X-ray fiber diffraction data suggests that the peptide molecules are hydrogen-bonded in a helical arrangement along the nanotube axis. PMID:23955926

  5. Effect of aging on phosphate metabolites of rat brain as revealed by the in vivo and in vitro sup 31 P NMR measurements

    SciTech Connect

    Liu, Hsiuchih; Chi, Chinwen; Liu, Tsungyun; Liu, Lianghui ); Luh, Wenming; Hsieh, Changhuain; Wu, Wenguey )

    1991-01-01

    Changes of phosphate metabolism in brains of neonate, weaning and adult rats were compared using both in vivo and in vitro nuclear magnetic resonance spectra. Ratios of phosphocreatine/nucleoside triphosphate (PCr/NTP) were the same in neonatal brain in both in vivo and in vitro studies, but not in weaning and adult brains. This discrepancy may have resulted from extended cerebral hypoxia due to slowed freezing of the brain by the increased skull thickness and brain mass in the weaning and adult rats. Variations of in vitro extraction condition for this age-related study may lead to systematic errors in the adult rats. Nevertheless, the phosphomonoester/nucleoside triphosphate (PME/NTP) ratios in extracts of brain from neonatal rats were higher than those obtained in vivo. In addition, the glycerophosphorylethanolamine plus glycerophosphorylcholine/nucleoside triphosphate (GPE+GPC/NTP) ratios, which were not measurable in vivo, showed age-dependent increase in extracts of rat brain. Some of the phosphomonoester and phosphodiester molecules in rat brain may be undetectable in in vivo NMR analysis because of their interaction with cellular components. The total in vitro GPE and GPC concentration in brain from neonatal rat was estimated to be 0.34 mmole/g wet tissue.

  6. A method for helical RNA global structure determination in solution using small-angle x-ray scattering and NMR measurements.

    PubMed

    Wang, Jinbu; Zuo, Xiaobing; Yu, Ping; Xu, Huan; Starich, Mary R; Tiede, David M; Shapiro, Bruce A; Schwieters, Charles D; Wang, Yun-Xing

    2009-10-30

    We report a "top-down" method that uses mainly duplexes' global orientations and overall molecular dimension and shape restraints, which were extracted from experimental NMR and small-angle X-ray scattering data, respectively, to determine global architectures of RNA molecules consisting of mostly A-form-like duplexes. The method is implemented in the G2G (from global measurement to global structure) toolkit of programs. We demonstrate the efficiency and accuracy of the method by determining the global structure of a 71-nt RNA using experimental data. The backbone root-mean-square deviation of the ensemble of the calculated global structures relative to the X-ray crystal structure is 3.0+/-0.3 A using the experimental data and is only 2.5+/-0.2 A for the three duplexes that were orientation restrained during the calculation. The global structure simplifies interpretation of multidimensional nuclear Overhauser spectra for high-resolution structure determination. The potential general application of the method for RNA structure determination is discussed. PMID:19666030

  7. Electrophoretic and aggregation behavior of bovine, horse and human red blood cells in plasma and in polymer solutions.

    PubMed

    Bäumler, H; Neu, B; Mitlöhner, R; Georgieva, R; Meiselman, H J; Kiesewetter, H

    2001-01-01

    The electrophoretic mobility of native and glutaraldehyde-fixed bovine, human, and horse red blood cells (RBC) was investigated as a function of ionic strength (5-150 mM) and concentration of 464 kDa dextran (2 and 3 g/dl); RBC aggregation in autologous plasma and in dextran solutions was also measured. In agreement with previous observations, human and horse RBC form stable rouleaux whereas bovine RBC do not aggregate in either plasma or in dextran 464 kDa solutions. Electrophoretic measurements showed a species-dependent adsorption and depletion of dextran that can be theoretically evaluated. Adsorption of polymer is not a prerequisite for RBC aggregation (bovine RBC show the highest amount of adsorbed dextran yet do not aggregate). Aggregate formation thus occurs as long as the Gibbs free energy difference, given by the osmotic pressure difference between the bulk phase and the polymer-depleted region between two RBC, is larger than the steric and electrostatic repulsive energy contributed by the macromolecules present on the RBC surface. With increasing bulk-phase polymer concentration the depletion layer thickness decreases and the amount of adsorbed macromolecules increases, thereby resulting in an increase of the repulsive component of the interaction energy and decreased aggregation. We thus view electrophoretic measurements of RBC in various media as an important tool for understanding polymer behavior near the red cell surface and hence the mechanisms involved in RBC aggregation. PMID:11381164

  8. Accurate measurement of heteronuclear dipolar couplings by phase-alternating R-symmetry (PARS) sequences in magic angle spinning NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Hou, Guangjin; Lu, Xingyu; Vega, Alexander J.; Polenova, Tatyana

    2014-09-01

    We report a Phase-Alternating R-Symmetry (PARS) dipolar recoupling scheme for accurate measurement of heteronuclear 1H-X (X = 13C, 15N, 31P, etc.) dipolar couplings in MAS NMR experiments. It is an improvement of conventional C- and R-symmetry type DIPSHIFT experiments where, in addition to the dipolar interaction, the 1H CSA interaction persists and thereby introduces considerable errors in the dipolar measurements. In PARS, phase-shifted RN symmetry pulse blocks applied on the 1H spins combined with π pulses applied on the X spins at the end of each RN block efficiently suppress the effect from 1H chemical shift anisotropy, while keeping the 1H-X dipolar couplings intact. Another advantage over conventional DIPSHIFT experiments, which require the signal to be detected in the form of a reduced-intensity Hahn echo, is that the series of π pulses refocuses the X chemical shift and avoids the necessity of echo formation. PARS permits determination of accurate dipolar couplings in a single experiment; it is suitable for a wide range of MAS conditions including both slow and fast MAS frequencies; and it assures dipolar truncation from the remote protons. The performance of PARS is tested on two model systems, [15N]-N-acetyl-valine and [U-13C,15N]-N-formyl-Met-Leu-Phe tripeptide. The application of PARS for site-resolved measurement of accurate 1H-15N dipolar couplings in the context of 3D experiments is presented on U-13C,15N-enriched dynein light chain protein LC8.

  9. Accurate measurement of heteronuclear dipolar couplings by phase-alternating R-symmetry (PARS) sequences in magic angle spinning NMR spectroscopy

    SciTech Connect

    Hou, Guangjin E-mail: tpolenov@udel.edu; Lu, Xingyu E-mail: lexvega@comcast.net; Vega, Alexander J. E-mail: lexvega@comcast.net; Polenova, Tatyana E-mail: tpolenov@udel.edu

    2014-09-14

    We report a Phase-Alternating R-Symmetry (PARS) dipolar recoupling scheme for accurate measurement of heteronuclear {sup 1}H-X (X = {sup 13}C, {sup 15}N, {sup 31}P, etc.) dipolar couplings in MAS NMR experiments. It is an improvement of conventional C- and R-symmetry type DIPSHIFT experiments where, in addition to the dipolar interaction, the {sup 1}H CSA interaction persists and thereby introduces considerable errors in the dipolar measurements. In PARS, phase-shifted RN symmetry pulse blocks applied on the {sup 1}H spins combined with π pulses applied on the X spins at the end of each RN block efficiently suppress the effect from {sup 1}H chemical shift anisotropy, while keeping the {sup 1}H-X dipolar couplings intact. Another advantage over conventional DIPSHIFT experiments, which require the signal to be detected in the form of a reduced-intensity Hahn echo, is that the series of π pulses refocuses the X chemical shift and avoids the necessity of echo formation. PARS permits determination of accurate dipolar couplings in a single experiment; it is suitable for a wide range of MAS conditions including both slow and fast MAS frequencies; and it assures dipolar truncation from the remote protons. The performance of PARS is tested on two model systems, [{sup 15}N]-N-acetyl-valine and [U-{sup 13}C,{sup 15}N]-N-formyl-Met-Leu-Phe tripeptide. The application of PARS for site-resolved measurement of accurate {sup 1}H-{sup 15}N dipolar couplings in the context of 3D experiments is presented on U-{sup 13}C,{sup 15}N-enriched dynein light chain protein LC8.

  10. NMR and MRI apparatus and method

    DOEpatents

    Clarke, John; Kelso, Nathan; Lee, SeungKyun; Moessle, Michael; Myers, Whittier; McDermott, Robert; ten Haken, Bernard; Pines, Alexander; Trabesinger, Andreas

    2007-03-06

    Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. Additional signal to noise benefits are obtained by use of a low noise polarization coil, comprising litz wire or superconducting materials. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

  11. Probing porous media with gas diffusion NMR.

    PubMed

    Mair, R W; Wong, G P; Hoffmann, D; Hurlimann, M D; Patz, S; Schwartz, L M; Walsworth, R L

    1999-10-18

    We show that gas diffusion nuclear magnetic resonance (GD-NMR) provides a powerful technique for probing the structure of porous media. In random packs of glass beads, using both laser-polarized and thermally polarized xenon gas, we find that GD-NMR can accurately measure the pore space surface-area-to-volume ratio, S/V rho, and the tortuosity, alpha (the latter quantity being directly related to the system's transport properties). We also show that GD-NMR provides a good measure of the tortuosity of sandstone and complex carbonate rocks. PMID:11543587

  12. Probing porous media with gas diffusion NMR

    NASA Technical Reports Server (NTRS)

    Mair, R. W.; Wong, G. P.; Hoffmann, D.; Hurlimann, M. D.; Patz, S.; Schwartz, L. M.; Walsworth, R. L.

    1999-01-01

    We show that gas diffusion nuclear magnetic resonance (GD-NMR) provides a powerful technique for probing the structure of porous media. In random packs of glass beads, using both laser-polarized and thermally polarized xenon gas, we find that GD-NMR can accurately measure the pore space surface-area-to-volume ratio, S/V rho, and the tortuosity, alpha (the latter quantity being directly related to the system's transport properties). We also show that GD-NMR provides a good measure of the tortuosity of sandstone and complex carbonate rocks.

  13. Glutamatergic and GABAergic energy metabolism measured in the rat brain by (13) C NMR spectroscopy at 14.1 T.

    PubMed

    Duarte, João M N; Gruetter, Rolf

    2013-09-01

    Energy metabolism supports both inhibitory and excitatory neurotransmission processes. This study investigated the specific contribution of astrocytic metabolism to γ-aminobutyric acid (GABA) synthesis and inhibitory GABAergic neurotransmission that remained to be ilucidated in vivo. Therefore, we measured (13)C incorporation into brain metabolites by dynamic (13)C nuclear magnetic resonance spectroscopy at 14.1 T in rats under α-chloralose anaesthesia during infusion of [1,6-(13)C]glucose. The enhanced sensitivity at 14.1 T allowed to quantify incorporation of (13) C into the three aliphatic carbons of GABA non-invasively. Metabolic fluxes were determined with a mathematical model of brain metabolism comprising glial, glutamatergic and GABAergic compartments. GABA synthesis rate was 0.11 ± 0.01 μmol/g/min. GABA-glutamine cycle was 0.053 ± 0.003 μmol/g/min and accounted for 22 ± 1% of total neurotransmitter cycling between neurons and glia. Cerebral glucose oxidation was 0.47 ± 0.02 μmol/g/min, of which 35 ± 1% and 7 ± 1% was diverted to the glutamatergic and GABAergic tricarboxylic acid cycles, respectively. The remaining fraction of glucose oxidation was in glia, where 12 ± 1% of the TCA cycle flux was dedicated to oxidation of GABA. 16 ± 2% of glutamine synthesis was provided to GABAergic neurons. We conclude that substantial metabolic activity occurs in GABAergic neurons and that glial metabolism supports both glutamatergic and GABAergic neurons in the living rat brain. PMID:23745684

  14. Characterization of CNT-MnO2 nanocomposite by electrophoretic deposition as potential electrode for supercapacitor

    NASA Astrophysics Data System (ADS)

    Darari, Alfin; Ardiansah, Hafidh Rahman; Arifin, Rismaningsih, Nurmanita; Ningrum, Andini Novia; Subagio, Agus

    2016-04-01

    Energy crisis that occured in Indonesia suggests that energy supply could not offset the high rate request and needs an electric energy saving device which can save high voltage, safety, and unlimited lifetime. The weakness of batteries is durable but has a low power density while the capacitor has a high power density but it doesn't durable. The renewal of this study is CNT-MnO2 thin film fabrication method using electrophoretic deposition. Electrophoretic deposition is a newest method to deposited CNT using power supply with cheap, and make a good result. The result of FTIR analysis showed that the best CNT-MnO2 composition is 75:25 and C-C bond is detected in fingerprint area. The result is electrode thin film homogen and characterized by X-ray diffraction (XRD) peaks 2θ=26,63° is characterization of graphite, and 2θ=43,97° is characterization of diamond Carbon type and measured by Scherrer formula results 52,3 nm material average size .EIS test results its capacitance about 7,86 F. from the data it can be concluded that CNT-MnO2 potential electrode very promising for further study and has a potential to be a high capacitance, and fast charge supercapacitor which can be applied for electronic devices, energy converter, even electric car.

  15. Effect of nanodroplet ink concentration on image contrast for reverse-emulsion electrophoretic displays

    NASA Astrophysics Data System (ADS)

    Wang, Winston Kuantung

    Reverse-emulsion electrophoretic display technology is based on an electro-responsive ink comprised of self-assembled nanodroplets dispersed in a non-polar liquid. The dye-containing nanodroplets are selectively driven toward or away from the viewing plane of a display by electric fields. The hypothesis of this study is that image contrast in a nanodroplet electrophoretic display is governed by concentration and steric effects that limit the intensity of the dark state. Simultaneously, steric effects as well as electrostatic screening can diminish whiteness in the light state. This hypothesis has been tested by multiphysics simulation of dilute species in electrostatic fields and experimental measurements of relative luminance in test displays. Concentration level was varied in a range of dilutions from full concentration (100%) to one-eighth (12.5%) and the highest contrast ratio was achieved at 25%. The test devices exhibited behavior that was similar to the saturation effects predicted by simulation, accounting for steric effects. Ink concentration showed little effect on switching time, reaching steady-state within approximately 2 seconds for all concentration levels. The hypothesis was further tested by experimentally observing the effect of driving voltage between 1 V to 8 V. The results showed no significant improvement of contrast even at higher voltage, further suggesting that concentration and steric effects dictate maximum contrast.

  16. Hydroxyapatite-anatase-carbon nanotube nanocomposite coatings fabricated by electrophoretic codeposition for biomedical applications.

    PubMed

    Zhang, Bokai; Kwok, Chi Tat

    2011-10-01

    In order to eliminate micro-cracks in the monolithic hydroxyapatite (HA) and composite hydroxyapatite/carbon nanotube (HA/CNT) coatings, novel HA/TiO(2)/CNT nanocomposite coatings on Ti6Al4V were attempted to fabricate by a single-step electrophoretic codeposition process for biomedical applications. The electrophoretically deposited layers with difference contents of HA, TiO(2) (anatase) and CNT nanoparticles were sintered at 800°C for densification with thickness of about 7-10 μm. A dense and crack-free coating was achieved with constituents of 85 wt% HA, 10 wt% TiO(2) and 5 wt% CNT. Open-circuit potential measurements and cyclic potentiodynamic polarization tests were used to investigate the electrochemical corrosion behavior of the coatings in vitro conditions (Hanks' solution at 37°C). The HA/TiO(2)/CNT coatings possess higher corrosion resistance than that of the Ti6Al4V substrate as reflected by nobler open circuit potential and lower corrosion current density. In addition, the surface hardness and adhesion strength of the HA/TiO(2)/CNT coatings are higher than that of the monolithic HA and HA/CNT coatings without compromising their apatite forming ability. The enhanced properties were attributed to the nanostructure of the coatings with the appropriate TiO(2) and CNT contents for eliminating micro-cracks and micro-pores. PMID:21850513

  17. Hexokinase inhibitor screening based on adenosine 5'-diphosphate determination by electrophoretically mediated microanalysis.

    PubMed

    Wang, Tongdan; Kang, Jingwu

    2009-04-01

    A CE-based method for hexokinase inhibitor screening was developed in the present paper. In this method, hexokinase activity was assayed via electrophoretically mediated microanalysis (EMMA), which combines on-column hexokinase-mediated reaction and measurement of produced adenosine 5'-diphosphate (ADP) via electrophoretical separation and UV detection. Enzyme inhibition can be read out directly from the reduced peak area of ADP in comparison with a reference electropherogram obtained in the absence of any inhibitor. Conditions for on-column enzyme reaction and separation of adenosine 5'-triphosphate (ATP) and ADP were optimized. The optimal buffer composition for enzymatic reaction was 25 mM HEPES buffer (pH 7.5) containing 5 mM MgCl(2), whereas the optimal buffer composition for separation was 100 mM Tris-phosphate buffer (pH 5.5) containing 0.02% (m/v) hexadimethrine bromide (HDB). Fortunately, discontinuous buffer system can be adapted easily in the EMMA method. The time for separation was reduced dramatically to less than 3 min by reversing the direction of EOF via dynamically coating the capillary wall with the cationic polyelectrolyte HDB. Moreover, the peak tailing of ATP was also reduced by HDB coating. The Z' factor as high as 0.98 was obtained, indicating a high quality of the screening data. The present method is simple, robust and cost-effective. PMID:19306267

  18. NMR studies of multiphase flows II

    SciTech Connect

    Altobelli, S.A.; Caprihan, A.; Fukushima, E.

    1995-12-31

    NMR techniques for measurements of spatial distribution of material phase, velocity and velocity fluctuation are being developed and refined. Versions of these techniques which provide time average liquid fraction and fluid phase velocity have been applied to several concentrated suspension systems which will not be discussed extensively here. Technical developments required to further extend the use of NMR to the multi-phase flow arena and to provide measurements of previously unobtainable parameters are the focus of this report.

  19. Two dimensional NMR spectroscopy

    SciTech Connect

    Schram, J.; Bellama, J.M.

    1988-01-01

    Two dimensional NMR represents a significant achievement in the continuing effort to increase solution in NMR spectroscopy. This book explains the fundamentals of this new technique and its analytical applications. It presents the necessary information, in pictorial form, for reading the ''2D NMR,'' and enables the practicing chemist to solve problems and run experiments on a commercial spectrometer by using the software provided by the manufacturer.

  20. Tunable electrophoretic separations using a scalable, fabric-based platform.

    PubMed

    Narahari, Tanya; Dendukuri, Dhananjaya; Murthy, Shashi K

    2015-02-17

    There is a rising need for low-cost and scalable platforms for sensitive medical diagnostic testing. Fabric weaving is a mature, scalable manufacturing technology and can be used as a platform to manufacture microfluidic diagnostic tests with controlled, tunable flow. Given its scalability, low manufacturing cost (<$0.25 per device), and potential for patterning multiplexed channel geometries, fabric is a viable platform for the development of analytical devices. In this paper, we describe a fabric-based electrophoretic platform for protein separation. Appropriate yarns were selected for each region of the device and weaved into straight channel electrophoretic chips in a single step. A wide dynamic range of analyte molecules ranging from small molecule dyes (<1 kDa) to macromolecule proteins (67-150 kDa) were separated in the device. Individual yarns behave as a chromatographic medium for electrophoresis. We therefore explored the effect of yarn and fabric parameters on separation resolution. Separation speed and resolution were enhanced by increasing the number of yarns per unit area of fabric and decreasing yarn hydrophilicity. However, for protein analytes that often require hydrophilic, passivated surfaces, these effects need to be properly tuned to achieve well-resolved separations. A fabric device tuned for protein separations was built and demonstrated. As an analytical output parameter for this device, the electrophoretic mobility of a sedimentation marker, Naphthol Blue Black bovine albumin in glycine-NaOH buffer, pH 8.58 was estimated and found to be -2.7 × 10(-8) m(2) V(-1) s(-1). The ability to tune separation may be used to predefine regions in the fabric for successive preconcentrations and separations. The device may then be applied for the multiplexed detection of low abundance proteins from complex biological samples such as serum and cell lysate. PMID:25582166

  1. Electrophoretic separation of kidney and pituitary cells on STS-8

    NASA Technical Reports Server (NTRS)

    Morrison, D. R.; Nachtwey, D. S.; Barlow, G. H.; Cleveland, C.; Lanham, J. W.; Farrington, M. A.; Hatfield, J. M.; Hymer, W. C.; Grindeland, R.; Lewis, M. L.

    1984-01-01

    Specific secretory cells were separated from suspensions of cultured primary human embryonic cells and rat pituitary cells in microgravity conditions, with an objective of isolating the subfractions of kidney cells that produce the largest amount of urakinase, and the subfractions of rat pituitary cells that secrete growth hormones (GH), prolactin (PRL), and other hormones. It is inferred from the experimental observations that the surface charge distributions of the GH-containing cells differ from those of the PRL-containing cells, which is explained by the presence of secretory products on the surface of pituitary cells. For kidney cells, the electrophoretic mobility distributions in flight experiments were spread more than the ground controls.

  2. Selectively-etched nanochannel electrophoretic and electrochemical devices

    DOEpatents

    Surh, Michael P.; Wilson, William D.; Barbee, Jr., Troy W.; Lane, Stephen M.

    2006-06-27

    Nanochannel electrophoretic and electrochemical devices having selectively-etched nanolaminates located in the fluid transport channel. The normally flat surfaces of the nanolaminate having exposed conductive (metal) stripes are selectively-etched to form trenches and baffles. The modifications of the prior utilized flat exposed surfaces increase the amount of exposed metal to facilitate electrochemical redox reaction or control the exposure of the metal surfaces to analytes of large size. These etched areas variously increase the sensitivity of electrochemical detection devices to low concentrations of analyte, improve the plug flow characteristic of the channel, and allow additional discrimination of the colloidal particles during cyclic voltammetry.

  3. Antisera against electrophoretically purified tubulin stimulate colchicine-binding activity.

    PubMed

    Aubin, J E; Subrahmanyan, L; Kalnins, V I; Ling, V

    1976-04-01

    Several rabbit antisera have been prepared against reduced and alkylated, electrophoretically purified tubulin isolated from chick brain. These antisera give a single precipitin line in Ouchterlony double diffusion plates when tested against partially purified tubulin, and label specifically microtubule- and tubulin-containing structures, such as mitotic spindles, cilia, and vinblastine-induced crystals, in a variety of cells. The same antisera also display the unique ability to stimulate the colchicine-binding activity of tubulin preparations from chick brain and Chinese hamster ovary tissue culture cells. This specific stimulation of colchicine binding activity is also obtained with the gamma globulin fractions purified by ammonium sulfate precipitation of these antisera. PMID:57619

  4. Selectively-etched nanochannel electrophoretic and electrochemical devices

    SciTech Connect

    Surh, Michael P.; Wilson, William D.; Barbee, Jr., Troy W.; Lane, Stephen M.

    2004-11-16

    Nanochannel electrophoretic and electrochemical devices having selectively-etched nanolaminates located in the fluid transport channel. The normally flat surfaces of the nanolaminate having exposed conductive (metal) stripes are selectively-etched to form trenches and baffles. The modifications of the prior utilized flat exposed surfaces increase the amount of exposed metal to facilitate electrochemical redox reaction or control the exposure of the metal surfaces to analytes of large size. These etched areas variously increase the sensitivity of electrochemical detection devices to low concentrations of analyte, improve the plug flow characteristic of the channel, and allow additional discrimination of the colloidal particles during cyclic voltammetry.

  5. Electrophoretically induced aqueous flow through single-wall carbon nanotube membranes

    PubMed Central

    Wu, Ji; Gerstandt, Karen; Zhang, Hongbo; Liu, Jie; Hinds, Bruce. J.

    2013-01-01

    Electrophoresis, the motion of charged species through liquids and pores under an external electric field, has been principle source of chemical pumping for numerous micro- and nano-fluidic devices platforms. Recent studies of ion current through single or few carbon nanotube channels range from near bulk mobility to 2-7 orders of magnitude of enhancement but cannot directly measure ion flux. Membranes, with large number of nanotube pores, allow independent confirmation of ion current and flux. Here we report that the aqueous electrophoretic mobility of ions within the graphitic cores of carbon nanotube membranes, with a uniform pore size of 0.9 ± 0.2 nm, is enhanced ∼3 times that of bulk mobilities. The induced electroosmotic velocities are 4 orders of magnitude faster than those measured in conventional porous materials. We also show that a nanotube membrane can function as a rectifying diode due to ionic steric effects within tightly controlled nanotube diameter. PMID:22245860

  6. Multiecho scheme advances surface NMR for aquifer characterization

    NASA Astrophysics Data System (ADS)

    Grunewald, Elliot; Walsh, David

    2013-12-01

    nuclear magnetic resonance (NMR) is increasingly used as a method to noninvasively characterize aquifers. This technology follows a successful history of NMR logging, applied over decades to estimate hydrocarbon reservoir properties. In contrast to logging, however, surface methods have utilized relatively simple acquisition sequences, from which pore-scale properties may not be reliably and efficiently estimated. We demonstrate for the first time the capability of sophisticated multiecho measurements to rapidly record a surface NMR response that more directly reflects aquifer characteristics. Specifically, we develop an adaptation of the multipulse Carr-Purcell-Meiboom-Gill (CPMG) sequence, widely used in logging, to measure the T2 relaxation response in a single scan. We validate this approach in a field surface NMR data set and by direct comparison with an NMR log. Adoption of the CPMG marked a landmark advancement in the history of logging NMR; we have now realized this same advancement in the surface NMR method.

  7. Cross-Correlated Relaxation of Dipolar Coupling and Chemical-Shift Anisotropy in Magic-Angle Spinning R1ρ NMR Measurements: Application to Protein Backbone Dynamics Measurements.

    PubMed

    Kurauskas, Vilius; Weber, Emmanuelle; Hessel, Audrey; Ayala, Isabel; Marion, Dominique; Schanda, Paul

    2016-09-01

    Transverse relaxation rate measurements in magic-angle spinning solid-state nuclear magnetic resonance provide information about molecular motions occurring on nanosecond-to-millisecond (ns-ms) time scales. The measurement of heteronuclear ((13)C, (15)N) relaxation rate constants in the presence of a spin-lock radiofrequency field (R1ρ relaxation) provides access to such motions, and an increasing number of studies involving R1ρ relaxation in proteins have been reported. However, two factors that influence the observed relaxation rate constants have so far been neglected, namely, (1) the role of CSA/dipolar cross-correlated relaxation (CCR) and (2) the impact of fast proton spin flips (i.e., proton spin diffusion and relaxation). We show that CSA/D CCR in R1ρ experiments is measurable and that the CCR rate constant depends on ns-ms motions; it can thus provide insight into dynamics. We find that proton spin diffusion attenuates this CCR due to its decoupling effect on the doublet components. For measurements of dynamics, the use of R1ρ rate constants has practical advantages over the use of CCR rates, and this article reveals factors that have so far been disregarded and which are important for accurate measurements and interpretation. PMID:27500976

  8. Squid detected NMR and MRI at ultralow fields

    SciTech Connect

    Clarke, John; McDermott, Robert; Pines, Alexander; Trabesinger, Andreas Heinz

    2007-05-15

    Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

  9. Squid detected NMR and MRI at ultralow fields

    DOEpatents

    Clarke, John; McDermott, Robert; Pines, Alexander; Trabesinger, Andreas Heinz

    2006-05-30

    Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

  10. SQUID detected NMR and MRI at ultralow fields

    DOEpatents

    Clarke, John; McDermott, Robert; Pines, Alexander; Trabesinger, Andreas Heinz

    2006-10-03

    Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

  11. Squid detected NMR and MRI at ultralow fields

    SciTech Connect

    Clarke, John; Pines, Alexander; McDermott, Robert F.; Trabesinger, Andreas H.

    2008-12-16

    Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

  12. NMR investigation of Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Son, Kwanghyo; Jang, Zeehoon

    2013-01-01

    109Ag nuclear magnetic resonance (NMR) and relaxation measurements have been performed on two powder samples of Ag nanoparticles with average sizes of 20 nm and 80 nm. The measurements have been done in an external field of 9.4 T and in the temperature range 10 K < T < 280 K. The 109Ag NMR spectra for both samples have close to Lorentzian shapes and turn out to be mixtures of homogeneous and inhomogeneous lines. The linewidth Δ ν at room temperature is 1.3 kHz for both samples and gradually increases with decreasing temperature. Both the Knight shift ( K) and the nuclear spin-lattice relaxation rate (1/ T 1) are observed to be almost identical to the values reported for the bulk Ag metal, whereby the Korringa ratio R(= K 2 T 1 T/S) is found to be 2.0 for both samples in the investigated temperature range.

  13. Lectures on pulsed NMR

    SciTech Connect

    Pines, A.

    1988-08-01

    These lectures discuss some recent developments in pulsed NMR, emphasizing fundamental principles with selected illustrative applications. Major topics covered include multiple-quantum spectroscopy, spin decoupling, the interaction of spins with a quantized field, adiabatic rapid passage, spin temperature and statistics of cross-polarization, coherent averaging, and zero field NMR. 32 refs., 56 figs.

  14. Lectures on pulsed NMR

    SciTech Connect

    Pines, A.

    1986-09-01

    These lectures discuss some recent developments in pulsed NMR, emphasizing fundamental principles with selected illustrative applications. Major topics covered include multiple-quantum spectroscopy, spin decoupling, the interaction of spins with a quantized field, adiabatic rapid passage, spin temperature and statistics of cross-polarization, coherent averaging, and zero field NMR. 55 figs.

  15. Electrophoretic karyotypes of clinical isolates of Coccidioides immitis.

    PubMed Central

    Pan, S; Cole, G T

    1992-01-01

    Chromosomes of the fungal respiratory pathogen, Coccidioides immitis, were separated by contour-clamped homogeneous electric field gel electrophoresis. Twelve isolates were examined, the majority of which showed four chromosomes with a range of molecular size from 11.5 to 3.2 Mb. Three isolates (C634, C735, and L) revealed three chromosomal bands under the conditions employed for electrophoretic separation. However, in two of these isolates (C634 and C735), four chromosomes were visible on membrane transfers of pulsed-field gels after Southern hybridization between the chromosomal DNA and selected DNA probes. The probes included a conserved ribosomal gene and three previously described cDNAs isolated from C. immitis expression libraries. The L isolate was determined to have the same genome size as a typical four-chromosome isolate on the basis of microspectrophotometric comparison of fluorescence intensity of the ethidium bromide-stained nuclear DNA. The genome size of C. immitis determined by microspectrophotometry was approximately 28.2 +/- 2.6 Mb. The calculated genome size based on addition of the average molecular weights of chromosomal bands separated by contour-clamped homogeneous electric field gel electrophoresis was approximately equal to the estimate derived from the spectrophotometric analyses. This is the first report of the electrophoretic karyotype of C. immitis. Images PMID:1398998

  16. [Analysis of proteins in food with electrophoretic and chromatographic methods].

    PubMed

    Kaiser, K P; Krause, I

    1985-03-01

    The efficiency of electrophoretic methods (gel electrophoresis, isoelectric focusing, twodimensional techniques) and of chromatographic methods (size exclusion and ion exchange chromatography, reversed phase HPLC) to analyze proteins in foods is reviewed. Several selected applications are discussed in detail. The large diversity of proteins in a particular food results in a unique electrophoretic or chromatographic pattern, that can be used for identification purposes, by means of the so called indicator proteins. The adaptability and resolving power of the methods assure their extended application to many protein containing foods. The uniqueness of the patterns obtained warranties differentiations of even closely related animal or plant foods as well as mixtures of them. The methods also allow quantitative determinations of mixtures of foods. Their ease of handling and good reproducibility and reliability favours their use in routine analyses. Numerous investigations on fish, meat and derived products, non-meat proteins in meat products, milk, cheese, cereals and products made of cereals, oilseed proteins, legumes, fruits and vegetables described in the literature are here presented. PMID:3890408

  17. Electrophoretic mobility of cells in a vertical Ficoll gradiant

    NASA Technical Reports Server (NTRS)

    Plank, L. D.; Todd, P. W.; Kunze, M. E.; Gaines, R. A.

    1985-01-01

    The upward migration of living cells and test particles under the influence of a constant electric field in a low conductivity Ficoll gradient occurs at nearly constant velocity. Viscosity and neutral polymer concentration affect migration rate. Decreasing viscosity speeds up the particle migration, decreasing neutral polymer (Ficoll) concentration, slows particle migration, since electrophoretic mobility increases approximately linearly with neutral polymer concentration. Neutral polymers interact with the cell surface to effectively raise its zeta potential. An analytic function was developed from the known dependence of these physical variables on migration distance; the analysis expresses migration velocity as an explicit function of position in the density gradient. It predicts an almost linear increase in velocity of about 12 to 16% over the working region of the gradient. It was numerically integrated and correctly predicts cell migration distance vs time curves without the use of any fitted parameters. The resulting migration curves follow the expected slowly varying exponential form that closely resembles a straight line. The ability to determine standard electrophoretic mobilities from such curves depends on knowledge of the effect of Ficoll on the zeta potential of the cell type that is separated.

  18. SEM Analysis of Electrophoretically-Deposited Nanoparticle Films

    NASA Astrophysics Data System (ADS)

    Verma, Neil

    Cobalt ferrite nanoparticles (20 nm) were synthesized and electrophoretically deposited onto aluminum foil, graphite paper, and carbon felt in order to study its potential as a cost-effective electrocatalyst for the oxidation of ammonium sulfite to ammonium sulfate in a proposed sulfur ammonia thermochemical cycle. Scanning electron microscopy and linear sweep voltammetry were used to characterize the deposited films and investigate their electrochemical activity. Furthermore, the effects of electrophoretic deposition conditions on deposit morphology and subsequently the effects of deposit morphology on electrochemical activity in 2 M ammonium sulfite were studied to better understand how to improve electrocatalysts. It was found that there is a critical deposit thickness for each substrate, where additional deposited particles reduce overall electrocatalytic activity of the deposits. For graphite paper, this thickness was estimated to be 3 particle layers for the EPD conditions studied. The 3 particle layer film on graphite paper resulted in a 5.5 fold increase in current density from a blank graphite paper substrate. For carbon felt, the deposit thickness threshold was calculated to be 0.13 of a particle layer for the EPD conditions studied. Moreover, this film was found to have a 4.3 fold increase in current density from a blank carbon felt substrate.

  19. Electrophoretic deposition of zinc-substituted hydroxyapatite coatings.

    PubMed

    Sun, Guangfei; Ma, Jun; Zhang, Shengmin

    2014-06-01

    Zinc-substituted hydroxyapatite nanoparticles synthesized by the co-precipitation method were used to coat stainless steel plates by electrophoretic deposition in n-butanol with triethanolamine as a dispersant. The effect of zinc concentration in the synthesis on the morphology and microstructure of coatings was investigated. It is found that the deposition current densities significantly increase with the increasing zinc concentration. The zinc-substituted hydroxyapatite coatings were analyzed by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. It is inferred that hydroxyapatite and triethanolamine predominate in the chemical composition of coatings. With the increasing Zn/Ca ratios, the contents of triethanolamine decrease in the final products. The triethanolamine can be burnt out by heat treatment. The tests of adhesive strength have confirmed good adhesion between the coatings and substrates. The formation of new apatite layer on the coatings has been observed after 7days of immersion in a simulated body fluid. In summary, the results show that dense, uniform zinc-substituted hydroxyapatite coatings are obtained by electrophoretic deposition when the Zn/Ca ratio reaches 5%. PMID:24863199

  20. Silver and Gold NMR

    PubMed Central

    Zangger, Klaus

    1999-01-01

    Silver and gold, together with copper, form the transition metal group IB elements in the periodic table and possess very different nuclear magnetic resonance (NMR) spectroscopic properties. While there is only one gold isotope (197Au), which has a spin of 3/2 and therefore a quadrupole moment, silver occurs in two isotopic forms (109Ag and 109Au), both of which have a spin 1/2 and similar NMR spectroscopic properties. The unfavorable properties of gold have prevented its NMR spectroscopic investigation thus far. On the other hand, there are several reports of silver NMR. However, the low sensitivity of silver, combined with its long relaxation times have rendered the direct detection of silver possible only with concentrations greater than a few tenth molar. Reviewed here are the general limitations of silver NMR and some techniques to partially overcome these limitations, as well as a summary of currently available chemical shift and scalar coupling data on 109Ag. PMID:18475898

  1. The influence of hydrodynamic slip on the electrophoretic mobility of a spherical colloidal particle

    NASA Astrophysics Data System (ADS)

    Khair, Aditya S.; Squires, Todd M.

    2009-04-01

    Recent theoretical studies have suggested a significant enhancement in electro-osmotic flows over hydrodynamically slipping surfaces, and experiments have indeed measured O(1) enhancements. In this paper, we investigate whether an equivalent effect occurs in the electrophoretic motion of a colloidal particle whose surface exhibits hydrodynamic slip. To this end, we compute the electrophoretic mobility of a uniformly charged spherical particle with slip length λ as a function of the zeta (or surface) potential of the particle ζ and diffuse-layer thickness κ-1. In the case of a thick diffuse layer, κa ≪1 (where a is the particle size), simple arguments show that slip does lead to an O(1) enhancement in the mobility, owing to the reduced viscous drag on the particle. On the other hand, for a thin-diffuse layer κa ≫1, the situation is more complicated. A detailed asymptotic analysis, following the method of O'Brien [J. Colloid Interface Sci. 92, 204 (1983)], reveals that an O(κλ) increase in the mobility occurs at low-to-moderate zeta potentials (with ζ measured on the scale of thermal voltage kBT /e≈25 mV). However, as ζ is further increased, the mobility decreases and ultimately becomes independent of the slip length—the enhancement is lost—which is due to the importance of nonuniform surface conduction within the thin-diffuse layer, at large ζ and large, but finite, κa. Our asymptotic calculations for thick and thin-diffuse layers are corroborated and bridged by computation of the mobility from the numerical solution of the full electrokinetic equations (using the method of O'Brien and White [J. Chem. Soc., Faraday Trans. 2 74, 1607 (1978)]). In summary, then, we demonstrate that hydrodynamic slip can indeed produce an enhancement in the electrophoretic mobility; however, such enhancements will not be as dramatic as the previously studied κa →∞ limit would suggest. Importantly, this conclusion applies not only to electrophoresis but also to

  2. Electrophoretic deposition of titanium dioxide films on copper in aqueous media.

    PubMed

    Laamari, M; Ben Youssef, A; Bousselmi, L

    2016-01-01

    Electrophoretic deposition was used to produce titanium dioxide (TiO2) nanostructured films on copper substrate in aqueous media for photocatalytic application. Polyvinyl pyrrolidone (PVP) with a weight rate from 0 to 15% was added to TiO2 P25 suspension in order to enhance film adhesion. The films were characterized by X-ray diffraction, optical microscopy, contact angle measurement, nanoindentation, scratch test and photoluminescence. The photocatalytic activity of the films was tested with amido black 10B under UV irradiation. The results indicated that the morphology and the mechanical properties of films depended on the added PVP amount. Scratch test showed that adhesion strength rose with increased PVP amount. The photocatalytic activity indicated that TiO2 film synthesized with 13% PVP had the highest efficiency. PMID:27438247

  3. Difference in microchip electrophoretic mobility between partially and fully PEGylated poly(amidoamine) dendrimers.

    PubMed

    Park, Eun Ji; Na, Dong Hee

    2015-11-01

    The objective of this study was to investigate the difference in electrophoretic mobility between partially and fully poly(ethylene glycol)-conjugated poly(amidoamine) dendrimers (part-PEG-PAMAM and full-PEG-PAMAM, respectively) using a microchip capillary gel electrophoresis (MCGE). While MCGE allowed size-based separation of PEG-PAMAMs prepared with monomethoxy PEG-nitrophenyl carbonate, full-PEG-PAMAMs migrated slower than part-PEG-PAMAMs that were similar in size or larger. When the measured molecular weights obtained from MCGE analysis and the calculated molecular weights were plotted, each part-PEG-PAMAM and full-PEG-PAMAM showed correlation coefficients greater than 0.98. This study indicates that MCGE would be useful for characterizing PEG-PAMAMs with different PEGylation degrees. PMID:26253023

  4. Site-resolved multiple-quantum filtered correlations and distance measurements by magic-angle spinning NMR: Theory and applications to spins with weak to vanishing quadrupolar couplings.

    PubMed

    Eliav, U; Haimovich, A; Goldbourt, A

    2016-01-14

    We discuss and analyze four magic-angle spinning solid-state NMR methods that can be used to measure internuclear distances and to obtain correlation spectra between a spin I = 1/2 and a half-integer spin S > 1/2 having a small quadrupolar coupling constant. Three of the methods are based on the heteronuclear multiple-quantum and single-quantum correlation experiments, that is, high rank tensors that involve the half spin and the quadrupolar spin are generated. Here, both zero and single-quantum coherence of the half spins are allowed and various coherence orders of the quadrupolar spin are generated, and filtered, via active recoupling of the dipolar interaction. As a result of generating coherence orders larger than one, the spectral resolution for the quadrupolar nucleus increases linearly with the coherence order. Since the formation of high rank tensors is independent of the existence of a finite quadrupolar interaction, these experiments are also suitable to materials in which there is high symmetry around the quadrupolar spin. A fourth experiment is based on the initial quadrupolar-driven excitation of symmetric high order coherences (up to p = 2S, where S is the spin number) and subsequently generating by the heteronuclear dipolar interaction higher rank (l + 1 or higher) tensors that involve also the half spins. Due to the nature of this technique, it also provides information on the relative orientations of the quadrupolar and dipolar interaction tensors. For the ideal case in which the pulses are sufficiently strong with respect to other interactions, we derive analytical expressions for all experiments as well as for the transferred echo double resonance experiment involving a quadrupolar spin. We show by comparison of the fitting of simulations and the analytical expressions to experimental data that the analytical expressions are sufficiently accurate to provide experimental (7)Li-(13)C distances in a complex of lithium, glycine, and water. Discussion

  5. Nuclear magnetic resonance apparatus having semitoroidal rf coil for use in topical NMR and NMR imaging

    DOEpatents

    Fukushima, Eiichi; Roeder, Stephen B. W.; Assink, Roger A.; Gibson, Atholl A. V.

    1986-01-01

    An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio-frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

  6. REDOR NMR for Drug Discovery

    PubMed Central

    Cegelski, Lynette

    2014-01-01

    Rotational-Echo DOuble-Resonance (REDOR) NMR is a powerful and versatile solid-state NMR measurement that has been recruited to elucidate drug modes of action and to drive the design of new therapeutics. REDOR has been implemented to examine composition, structure, and dynamics in diverse macromolecular and whole-cell systems, including taxol-bound microtubules, enzyme-cofactor-inhibitor ternary complexes, and antibiotic-whole-cell complexes. The REDOR approach involves the integrated design of specific isotopic labeling strategies and the selection of appropriate REDOR experiments. By way of example, this digest illustrates the versatility of the REDOR approach, with an emphasis on the practical considerations of experimental design and data interpretation. PMID:24035486

  7. 1H NMR relaxation in urea

    NASA Astrophysics Data System (ADS)

    Taylor, R. E.; Bacher, Alfred D.; Dybowski, C.

    2007-11-01

    Proton NMR spin-lattice relaxation times T1 were measured for urea as a function of temperature. An activation energy of 46.3 ± 4.7 kJ/mol was extracted and compared with the range of 38-65 kJ/mol previously reported in the literature as measured by different magnetic resonance techniques. In addition, proton NMR spin-lattice relaxation times in the rotating frame T1 ρ were measured as a function of temperature. These measurements provide acquisition conditions for the 13C and 15N CP/MAS spectra of pure urea in the crystalline phase.

  8. Interfaces in polymer nanocomposites - An NMR study

    NASA Astrophysics Data System (ADS)

    Böhme, Ute; Scheler, Ulrich

    2016-03-01

    Nuclear Magnetic Resonance (NMR) is applied for the investigation of polymer nanocomposites. Solid-state NMR is applied to study the modification steps to compatibilize layered double hydroxides with non-polar polymers. 1H relaxation NMR gives insight on the polymer dynamics over a wide range of correlation times. For the polymer chain dynamics the transverse relaxation time T2 is most suited. In this presentation we report on two applications of T2 measurements under external mechanical stress. In a low-field system relaxation NMR studies are performed in-situ under uniaxial stress. High-temperature experiments in a Couette cell permit the investigation of the polymer dynamics in the melt under shear flow.

  9. Electrophoretic assay of specific estrogen receptors: a contribution to methodology.

    PubMed

    van Netten, J P; Algard, F T; Montessori, G; Weare, B

    1977-11-01

    Experimental evidence is presented that supports the use of the cold agar-gel electrophoretic method for the clinical quantitation of specific estrogen-binding protein present in some human mammary carcinomas. It is necessary to dilute tumor extracts to avoid interference by serum-borne, non-relevant hormone-binding proteins such as albumin, which migrates to the same anodal region as does the binding protein. Dilution to 2.5 mg or less of total protein per milliliter circumvents such interference while still permitting reliable quantitation of the binding protein. Seventy-two mammary carcinomas were compared for binding-protein content by both the cold agar-gel electrophoresis and a single-point dextran-coated charcoal assay. The correlation coefficient (0.96) indicated excellent agreement between results by the two methods. In addition results are presented which indicate that the preparation of tumor extracts for electrophoresis does not require the use of an ultracentrifuge. PMID:912871

  10. Electrophoretic deposition of nickel zinc ferrite nanoparticles into microstructured patterns

    NASA Astrophysics Data System (ADS)

    Kelly, Stefan J.; Wen, Xiao; Arnold, David P.; Andrew, Jennifer S.

    2016-05-01

    Using DC electric fields, nickel-zinc ferrite (Ni0.5Zn0.5Fe2O4) nanoparticles (Dh =16.6 ± 3.6 nm) are electrophoretically deposited onto silicon substrates to form dense structures defined by photoresist molds. Parameters such as electric field, bath composition, and deposition time are tuned to produce films ranging in thickness from 177 to 805 nm. The deposited films exhibit soft magnetic properties with a saturation magnetization of 60 emu/g and a coercivity of 2.6 kA/m (33 Oe). Additionally, the influence of the photoresist mold on the deposit profile is studied, and patterned films with different shapes (lines, squares, circles, etc.) are demonstrated with feature sizes down to 5 μm.

  11. Electrophoretic Deposition of Carbon Nitride Layers for Photoelectrochemical Applications.

    PubMed

    Xu, Jingsan; Shalom, Menny

    2016-05-25

    Electrophoretic deposition (EPD) is used for the growth of carbon nitride (C3N4) layers on conductive substrates. EPD is fast, environmentally friendly, and allows the deposition of negatively charged C3N4 with different compositions and chemical properties. In this method, C3N4 can be deposited on various conductive substrates ranging from conductive glass and carbon paper to nickel foam possessing complex 3D geometries. The high flexibility of this approach enables us to readily tune the photophysical and photoelectronic properties of the C3N4 electrodes. The advantage of this method was further illustrated by the tailored construction of a heterostructure between two complementary C3N4, with marked photoelectrochemical activity. PMID:27148889

  12. New capabilities and applications for electrophoretically deposited coatings

    SciTech Connect

    Sharp, D.J.

    1991-01-01

    Our primary purpose in this test is to provide a brief general description of a few applications of various electrophoretic systems which have been investigated and have found use in various coating applications at Sandia National Laboratories. Both organic and inorganic suspensions in aqueous and non-aqueous media have been considered in these studies. Applications include high voltage insulating dielectrics, thermally conductive/electrically insulating films, adherent lubricating films, uniform photoresist films, glass coatings, and fissile uranium oxide/carbon composite films for studies of nuclear powered lasers. More recently, we have become interested in the beneficial environmental aspects of being able to provide protective polymer coatings which reduce or minimize the use of organic solvents required by traditional spray coat processes. Important practical factors which relate to film uniformity, adhesion, and composition are related to unique coating or plating capabilities and applications. 6 refs., 2 figs., 1 tab.

  13. Combined electrophoretic-separation and electrospray method and system

    DOEpatents

    Smith, Richard D.; Olivares, Jose A.

    1989-01-01

    A system and method for analyzing molecular constituents of a composition sample includes: forming a solution of the sample, separating the solution by capillary zone electrophoresis into an eluent of constituents longitudinally separated according to their relative electrophoretic mobilities, electrospraying the eluent to form a charged spray in which the molecular constituents have a temporal distribution; and detecting or collecting the separated constituents in accordance with the temporal distribution in the spray. A first high-voltage (e.g., 5-100 KVDC) is applied to the solution. The spray is charged by applying a second high voltage (e.g., .+-.2-8 KVDC) between the eluent at the capillary exit and a cathode spaced in front of the exit. A complete electrical circuit is formed by a conductor which directly contacts the eluent at the capillary exit.

  14. Studies on phytochrome. Some properties of electrophoretically pure phytochrome

    PubMed Central

    Walker, T. S.; Bailey, J. L.

    1970-01-01

    1. Phytochrome was purified from etiolated oat (Avena sativa) seedlings either by gel-filtration chromatography and ion-exchange chromatography or by gel-filtration chromatography and calcium phosphate chromatography. Differences were observed in the spectral properties of phytochrome isolated by the two methods. 2. Electrophoresis of pure phytochrome at pH values between 9.0 and 6.0 showed the tendency of phytochrome to form different molecular species. Studies in the ultracentrifuge did not show a corresponding change in the sedimentation coefficient with the change in pH. 3. Tryptic digestion of electrophoretically pure phytochrome gave 17 peptides and a photoactive core. The amino acid composition of the core is reported and compared with the analysis of whole phytochrome. 4. Some properties of phytochrome isolated from Pisum sativum are compared with those of phytochrome from A. sativa. 5. The properties of phytochrome purified by other workers are compared with our findings. ImagesFig. 4. PMID:5499974

  15. Preparation of guinea pig macrophage for electrophoretic experiments in space

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Methods of storage and cultivation of macrophage cells in preparation for space experiments were investigated. Results show that freezing and thawing immediately after extraction did not cause any change in viability or electrophoretic mobility of the cells. A prolonged storage at -80 C did cause cell damage as indicated by a 95% reduction in variable cells. Cell damage was decreased when Glycerol or Dimethyl Sulfoxide (DMSO) was added as a cryogenic protective agent. A 100% viability was observed in cultivation experiments after two weeks due to the additional serum. Results from gamma-glutamyl transpeptidase study showed a zero activity rate. It is suggested that a flat stationary field be used for the collection and use of macrophage. It was found that a 24-hour delay in obtaining macrophage cells helps to maintain a pure culture.

  16. Method for in-situ calibration of electrophoretic analysis systems

    DOEpatents

    Liu, Changsheng; Zhao, Hequan

    2005-05-08

    An electrophoretic system having a plurality of separation lanes is provided with an automatic calibration feature in which each lane is separately calibrated. For each lane, the calibration coefficients map a spectrum of received channel intensities onto values reflective of the relative likelihood of each of a plurality of dyes being present. Individual peaks, reflective of the influence of a single dye, are isolated from among the various sets of detected light intensity spectra, and these can be used to both detect the number of dye components present, and also to establish exemplary vectors for the calibration coefficients which may then be clustered and further processed to arrive at a calibration matrix for the system. The system of the present invention thus permits one to use different dye sets to tag DNA nucleotides in samples which migrate in separate lanes, and also allows for in-situ calibration with new, previously unused dye sets.

  17. Formation of diamond nanoparticle thin films by electrophoretic deposition

    NASA Astrophysics Data System (ADS)

    Goto, Yosuke; Ohishi, Fujio; Tanaka, Kuniaki; Usui, Hiroaki

    2016-03-01

    Thin films of diamond nanoparticles were prepared by electrophoretic deposition (EPD) using 0.5 wt % dispersions in water, ethanol, and 2-propanol. The film growth rate increased with increasing voltage applied to the electrodes. However, an excessive increase in voltage caused the degradation of film morphology. The optimum voltage was 4 V with an electrode separation of 5 mm. The film growth rate was higher in organic solvents than in water. The deposited film had a smooth surface with an average surface roughness comparable to the size of primary particles of the source material. It is notable that the EPD films had a considerably higher physical stability than spin-coated and cast films. The stability was further improved by thermally annealing the films. IR analysis revealed that the diamond nanoparticles have carboxy and amino groups on their surfaces. It is considered that the stability of the EPD films originate from a chemical reaction between these functional groups.

  18. Combined electrophoretic-separation and electrospray method and system

    DOEpatents

    Smith, R.D.; Olivares, J.A.

    1989-06-27

    A system and method for analyzing molecular constituents of a composition sample includes: forming a solution of the sample, separating the solution by capillary zone electrophoresis into an eluent of constituents longitudinally separated according to their relative electrophoretic mobilities, electrospraying the eluent to form a charged spray in which the molecular constituents have a temporal distribution; and detecting or collecting the separated constituents in accordance with the temporal distribution in the spray. A first high-voltage (e.g., 5--100 kVDC) is applied to the solution. The spray is charged by applying a second high voltage (e.g., [+-]2--8 kVDC) between the eluent at the capillary exit and a cathode spaced in front of the exit. A complete electrical circuit is formed by a conductor which directly contacts the eluent at the capillary exit. 10 figs.

  19. Electrophoretic Migration of Branched DNA in Polymer Solutions

    NASA Astrophysics Data System (ADS)

    Lau, Henry; Archer, Lynden

    2009-03-01

    The electrophoretic migration of large, star-branched DNA molecules has previously been studied in both neutral polymer solutions and gels, and the results have provided insight into the local interactions between the analytes and the sieving matrix during electrophoresis (Electrophoresis, 2006, 27, 3128). This talk focuses on using rigid-rod DNA molecules of complex shapes as model analytes in studying the effects of analyte architecture on mobility in polymer solutions. Electrophoresis of a series of Y-shaped DNA molecules that mimick the shapes of antibodies, was performed in polymer solutions above the overlap concentration and at electric fields up to 300V/cm. The location of the branch point as well as the arm sizes are varied in order to examine their influence on mobility. Our results point to novel, topology-based fractionation strategies for separating biological molecules using capillary electrophoresis with polymer sieving media.

  20. Simulations of electrophoretic collisions of DNA knots with gel obstacles

    NASA Astrophysics Data System (ADS)

    Weber, C.; DeLos Rios, P.; Dietler, G.; Stasiak, A.

    2006-04-01

    Gel electrophoresis can be used to separate nicked circular DNA molecules of equal length but forming different knot types. At low electric fields, complex knots drift faster than simpler knots. However, at high electric field the opposite is the case and simpler knots migrate faster than more complex knots. Using Monte Carlo simulations we investigate the reasons of this reversal of relative order of electrophoretic mobility of DNA molecules forming different knot types. We observe that at high electric fields the simulated knotted molecules tend to hang over the gel fibres and require passing over a substantial energy barrier to slip over the impeding gel fibre. At low electric field the interactions of drifting molecules with the gel fibres are weak and there are no significant energy barriers that oppose the detachment of knotted molecules from transverse gel fibres.

  1. Electrophoretic mobilities of counterions and a polymer in cylindrical pores

    PubMed Central

    Singh, Sunil P.; Muthukumar, M.

    2014-01-01

    We have simulated the transport properties of a uniformly charged flexible polymer chain and its counterions confined inside cylindrical nanopores under an external electric field. The hydrodynamic interaction is treated by describing the solvent molecules explicitly with the multiparticle collision dynamics method. The chain consisting of charged monomers and the counterions interact electrostatically with themselves and with the external electric field. We find rich behavior of the counterions around the polymer under confinement in the presence of the external electric field. The mobility of the counterions is heterogeneous depending on their location relative to the polymer. The adsorption isotherm of the counterions on the polymer depends nonlinearly on the electric field. As a result, the effective charge of the polymer exhibits a sigmoidal dependence on the electric field. This in turn leads to a nascent nonlinearity in the chain stretching and electrophoretic mobility of the polymer in terms of their dependence on the electric field. The product of the electric field and the effective polymer charge is found to be the key variable to unify our simulation data for various polymer lengths. Chain extension and the electrophoretic mobility show sigmoidal dependence on the electric field, with crossovers from the linear response regime to the nonlinear regime and then to the saturation regime. The mobility of adsorbed counterions is nonmonotonic with the electric field. For weaker and moderate fields, the adsorbed counterions move with the polymer and at higher fields they move opposite to the polymer's direction. We find that the effective charge and the mobility of the polymer decrease with a decrease in the pore radius. PMID:25240366

  2. Electrophoretic deposition of ultrasonicated and functionalized nanomaterials for multifunctional composites

    NASA Astrophysics Data System (ADS)

    An, Qi

    Recent advances in the synthesis and characterization of nanostructured composite materials have enabled a broad range of opportunities for engineering the properties of polymer-matrix materials. Carbon nanotubes (CNTs) are known to have exceptional mechanical, electrical and thermal properties. Because of their small size, CNTs can occupy regions between traditional micro-scale reinforcements and create a hierarchical micro/nano structure spanning several orders of magnitude. Since CNTs possess critical reinforcement dimensions below 100 nm, new opportunities exist for tailoring the fiber/matrix interphase regions and ultimately the mechanical and electrical performance of advanced fiber-composites with minimal impact on the fiber-dominated properties. This growing interest in nanoscale hybridization with conventional fiber reinforcement has highlighted the need to develop new processing techniques for successful CNT integration. In this work, a novel and industrially scalable approach for producing multi-scale hybrid carbon nanotube/fiber composites using an electrophoretic deposition (EPD) technique has been studied as an alternative to in situ chemical vapor deposition growth (CVD). EPD is a widely used industrial coating process employed in areas ranging from automotive to electronics production. The method has a number of benefits which include low energy use and the ability to homogenously coat complex shapes with well adhered films of controlled thickness and density. A stable aqueous dispersion of multi-walled carbon nanotubes (MWCNTs) was produced using a novel ozonolysis and ultrasonication (USO) technique that results in dispersion and functionalization in a single step. Networks of CNTs span between adjacent fibers and the resulting composites exhibit significant increases in electrical conductivity and considerable improvements in the interlaminar shear strength and fracture toughness. In order to better understand the underlying mechanisms behind the

  3. Development of Halbach magnet for portable NMR device

    NASA Astrophysics Data System (ADS)

    Doğan, N.; Topkaya, R.; Subaşi, H.; Yerli, Y.; Rameev, B.

    2009-03-01

    Nuclear magnetic resonance (NMR) has enormous potential for various applications in industry as the on-line or at-line test/control device of process environments. Advantage of NMR is its non-destructive nature, because it does not require the measurement probe to have a contact with the tested media. Despite of the recent progress in this direction, application of NMR in industry is still very limited. This is related to the technical and analytical complications of NMR as a method, and high cost of NMR analyzers available at the market. However in many applications, NMR is a very useful technique to test various products and to monitor quantitatively industrial processes. Fortunately usually there is no need in a high-field superconducting magnets to obtain the high-resolution spectra with the detailed information on chemical shifts and coupling-constant. NMR analyzers are designed to obtain the relaxation parameters by measuring the NMR spectra in the time domain rather than in frequency domain. Therefore it is possible to use small magnetic field (and low frequency of 2-60 MHz) in NMR systems, based on permanent magnet technology, which are specially designed for specific at-line and on-line process applications. In this work we present the permanent magnet system developed to use in the portative NMR devices. We discuss the experimental parameters of the designed Halbach magnet system and compare them with results of theoretical modelling.

  4. Rotational Doppler Effect and Barnett Field in Spinning NMR

    NASA Astrophysics Data System (ADS)

    Chudo, Hiroyuki; Harii, Kazuya; Matsuo, Mamoru; Ieda, Jun'ichi; Ono, Masao; Maekawa, Sadamichi; Saitoh, Eiji

    2015-04-01

    We report the observation of the rotational Doppler effect using nuclear magnetic resonance (NMR). We have developed a coil-spinning technique that enables measurements by rotating a detector and fixing a sample. We found that the rotational Doppler effect gives rise to NMR frequency shifts equal to the rotation frequency. We formulate the rotational Doppler effect and the Barnett field using a vector model for the nuclear magnetic moment. This formulation reveals that, with just the sample rotating, both effects cancel each other, thereby explaining the absence of an NMR frequency shift in conventional sample-spinning NMR measurements.

  5. Comparing highly ordered monolayers of nanoparticles fabricated using electrophoretic deposition: Cobalt ferrite nanoparticles versus iron oxide nanoparticles

    SciTech Connect

    Dickerson, James H.; Krejci, Alex J.; Garcia, Adriana -Mendoza; Sun, Shouheng; Pham, Viet Hung

    2015-08-01

    Ordered assemblies of nanoparticles remain challenging to fabricate, yet could open the door to many potential applications of nanomaterials. Here, we demonstrate that locally ordered arrays of nanoparticles, using electrophoretic deposition, can be extended to produce long-range order among the constituents. Voronoi tessellations along with multiple statistical analyses show dramatic increases in order compared with previously reported assemblies formed through electric field-assisted assembly. As a result, based on subsequent physical measurements of the nanoparticles and the deposition system, the underlying mechanisms that generate increased order are inferred.

  6. NMR Stark Spectroscopy: New Methods to Calibrate NMR Sensitivity to Electric Fields

    NASA Astrophysics Data System (ADS)

    Tarasek, Matthew R.

    The influence of electrostatics on NMR parameters is well accepted. Thus, NMR is a promising route to probe electrical features within molecules and materials. However, applications of NMR Stark effects (E-field induced changes in spin energy levels) have been elusive. I have developed new approaches to resolve NMR Stark effects from an applied E field. This calibrates nuclear probes whose spectral response might later be used to evaluate internal E fields that are critical to function, such as those due to local charge distributions or sample structure. I will present two novel experimental approaches for direct calibration of NMR quadrupolar Stark effects (QSEs). In the first, steady-state (few-second) excitation by an E field at twice the NMR frequency (2ω 0) is used to saturate spin magnetization. The extent of saturation vs. E-field amplitude calibrates the QSE response rate, while measurements vs sample orientation determine tensorial character. The second method instead synchronizes short (few µs) pulses of the 2ω0 E field with a multiple-pulse NMR sequence. This, “POWER” (Perturbations Observed With Enhanced Resolution) approach enables more accurate measure of small QSEs (i.e. few Hz spectral changes). A 2nd key advantage is the ability to define tensorial response without reorienting the sample, but instead varying the phase of the 2ω0 field. I will describe these experiments and my home-built NMR “Stark probe”, employed on a conventional wide-bore solid-state NMR system. Results with GaAs demonstrate each method, while extensions to a wider array of molecular and material systems may now be possible using these methods.

  7. Singlet-triplet separations measured by [sup 31]P[l brace][sup 1]H[r brace] NMR: Applications to quadruply bonded dimolybdenum and ditungsten complexes

    SciTech Connect

    Cotton, F.A.; Eglin, J.L.; Bo Hong; James, C.A. )

    1993-05-12

    A series of quadruply bonded dimolybdenum and ditungsten compounds M[sub 2]X[sub 4](PP)[sub 2] (M = Mo, W; PP = bidentate phosphine ligands; X = Cl, Br, I) with internal rotational angles [chi] varying from 0.0 to 69.4[degrees] have been studied. Their [sup 31]P[l brace][sup 1]H[r brace] NMR spectra are characterized by their temperature-dependent shifts and line widths that broaden with increasing temperature. A nonlinear, least-squares fit of this temperature dependence of the paramagnetic shifts for their NMR signals allows the evaluation of the singlet-triplet energy separation ([minus]2J), the diamagnetic shift (H[sub dia]), and the electron-nucleus hyperfine coupling constant (A). The singlet-triplet energy separations for all the compounds investigated are found to be in the range 1200-3000 cm[sup [minus]1]. It is now clearly established that the ground state remains [sup 1]A[sub 1g] ([delta][sup 2]) even at [chi] = 45[degrees], where [sup 3]A[sub 2u] ([delta][delta]*) lies 1230 cm[sup [minus]1] above it. The [delta]-bond energy and electronic [delta]-barrier can also be experimentally estimated as 13.8[+-]0.5 kcal mol[sup [minus]1] and 10.3[+-]0.5 kcal mol[sup [minus]1], respectively. 32 refs., 3 figs., 1 tab.

  8. NMR imaging microscopy

    SciTech Connect

    Not Available

    1986-10-01

    In the past several years, proton nuclear magnetic resonance (NMR) imaging has become an established technique in diagnostic medicine and biomedical research. Although much of the work in this field has been directed toward development of whole-body imagers, James Aguayo, Stephen Blackband, and Joseph Schoeninger of the Johns Hopkins University School of Medicine working with Markus Hintermann and Mark Mattingly of Bruker Medical Instruments, recently developed a small-bore NMR microscope with sufficient resolution to image a single African clawed toad cell (Nature 1986, 322, 190-91). This improved resolution should lead to increased use of NMR imaging for chemical, as well as biological or physiological, applications. The future of NMR microscopy, like that of many other newly emerging techniques, is ripe with possibilities. Because of its high cost, however, it is likely to remain primarily a research tool for some time. ''It's like having a camera,'' says Smith. ''You've got a way to look at things at very fine levels, and people are going to find lots of uses for it. But it is a very expensive technique - it costs $100,000 to add imaging capability once you have a high-resolution NMR, which itself is at least a $300,000 instrument. If it can answer even a few questions that can't be answered any other way, though, it may be well worth the cost.''

  9. Electrophoretic mobility of concentrated carbon black dispersions in a low-permittivity solvent by optical coherence tomography.

    PubMed

    Patel, Mehul N; Smith, P Griffin; Kim, Jihoon; Milner, Thomas E; Johnston, Keith P

    2010-05-15

    Electrophoretic mobilities of concentrated dispersions of carbon black particles in a low-permittivity solvent were measured using differential-phase optical coherence tomography (DP-OCT). An electrode spacing of only 0.18 mm enables measurement of highly concentrated dispersions up to 1 wt.% of highly absorbing carbon black particles with high electric fields at low potentials. The capabilities of this DP-OCT method, including high sensitivity, high spatial resolution, and strong electric fields, enable enhanced measurement of low electrophoretic mobilities encountered in low-permittivity solvents. The zeta potential of carbon black particles ranged from -24 mV to -12 mV as the concentration of surfactant sodium bis(2-ethyl-1-hexyl)sulfosuccinate (AOT) was increased from 1 mM to 100 mM. A mechanism is presented to explain the electrostatic charging of carbon black particles in terms of the partitioning of the ions between the reverse micelles in the double layer and the surfactant adsorbed on the particle surface, as AOT concentration is varied. PMID:20176365

  10. Electrophoretic dynamics of self-assembling branched DNA structures

    NASA Astrophysics Data System (ADS)

    Heuer, Daniel Milton

    This study advances our understanding of the electrophoretic dynamics of branched biopolymers and explores technologies designed to exploit their unique properties. New self-assembly techniques were developed to create branched DNA for visualization via fluorescence microscopy. Experiments in fixed gel networks reveal a distinct trapping behavior, in contrast with linear topologies. The finding that detection can be achieved by introducing a branch point contributes significantly to the field of separation science and can be exploited to develop new applications. Results obtained in polymer solutions point to identical mobilities for branched and linear topologies, despite large differences in their dynamics. This finding led to a new description of electrophoresis based on non-Newtonian viscoelastic effects in the electric double layer surrounding a charged object. This new theoretical framework presents a new outlook important not only to the electrophoretic physics of nucleic acids, but all charged objects including proteins, colloids, and nanoparticles. To study the behavior of smaller biopolymers, such as restriction fragments and recombination intermediates, a library of symmetrically branched DNA was synthesized followed by characterization in gels. The experimental results contribute a large body of information relating molecular architecture and the dynamics of rigid structures in an electric field. The findings allow us to create new separation technologies based on topology. These contributions can also be utilized in a number of different applications including the study of recombination intermediates and the separation of proteins according to structure. To demonstrate the importance of these findings, a sequence and mutation detection technique was envisioned and applied for genetic analysis. Restriction fragments from mutation "hotspots" in the p53 tumor suppressor gene, known to play a role in cancer development, were analyzed with this technique

  11. Structure and reactivity of lithium amides. /sup 6/Li, /sup 13/C, and /sup 15/N NMR spectroscopic studies and colligative measurements of lithium diphenylamide and lithium diphenylamide-lithium bromide complex solvated by tetrahydrofuran

    SciTech Connect

    DePue, J.S.; Collum, D.B.

    1988-08-03

    /sup 6/Li, /sup 13/C, and /sup 15/N NMR spectroscopic studies of lithium diphenylamide in THF/hydrocarbon solutions (THF = tetrahydrofuran) detected two different species. /sup 6/Li and /sup 15/N NMR spectroscopic studies of (/sup 6/Li, /sup 15/N)lithium diphenylamide showed the species observed at low THF concentrations to be a cyclic oligomer. Structural analogies provided strong support for a dimer while colligative measurements at 0/degrees/C indicated the dimer to be di- or trisolvated. On the basis of the observed mass action effects, the species appearing at intermediate THF concentrations is assigned as a contact or solvent-separated ion-paired monomer. Lithium diphenylamide forms a 1:1 adduct with lithium bromide at low THF concentrations. A combination of /sup 6/Li-/sup 15/N double labeling studies and colligative measurements supports a trisolvated cyclic mixed dimer structure. Although detailed spectroscopic studies at elevated THF concentrations were precluded by high fluctionality, the similarity of the /sup 13/C chemical shifts of lithium diphenylamide in the presence and absence of lithium bromide provide indirect evidence that the mixed dimer undergoes a THF concentration dependent dissociation to the monomeric amide and free lithium bromide. 24 references, 9 figures, 2 tables.

  12. Lithium ion diffusion measurements on a garnet-type solid conductor Li6.6La3Zr1.6Ta0.4O12 by using a pulsed-gradient spin-echo NMR method.

    PubMed

    Hayamizu, Kikuko; Matsuda, Yasuaki; Matsui, Masaki; Imanishi, Nobuyuki

    2015-09-01

    The garnet-type solid conductor Li7-xLa3Zr2-xTaxO12 is known to have high ionic conductivity. We synthesized a series of compositions of this conductor and found that cubic Li6.6La3Zr1.6Ta0.4O12 (LLZO-Ta) has a high ionic conductivity of 3.7×10(-4)Scm(-1) at room temperature. The (7)Li NMR spectrum of LLZO-Ta was composed of narrow and broad components, and the linewidth of the narrow component varied from 0.69kHz (300K) to 0.32kHz (400K). We carried out lithium ion diffusion measurements using pulsed-field spin-echo (PGSE) NMR spectroscopy and found that echo signals were observed at T≥313K with reasonable sensitivity. The lithium diffusion behavior was measured by varying the observation time and pulsed-field gradient (PFG) strength between 313 and 384K. We found that lithium diffusion depended significantly on the observation time and strength of the PFG, which is quite different from lithium ion diffusion in liquids. It was shown that lithium ion migration in the solid conductor was distributed widely in both time and space. PMID:26051010

  13. Wide-line NMR and protein hydration.

    PubMed

    Tompa, K; Bokor, M; Tompa, P

    2012-01-01

    In this chapter, the reader is introduced to the basics of wide-line NMR, with particular focus on the following: (1) basic theoretical and experimental NMR elements, necessary before switching the spectrometer and designing the experiment, (2) models/theories for the interpretation of measured data, (3) definition of wide-line NMR spectrometry, the description of the measurement and evaluation variants, useful hints for the novice, (4) advice on selecting the solvent, which is not a trivial task, (5) a note of warning that not all data are acceptable in spite of the statistical confidence. Finally, we wrap up the chapter with the results on two proteins (a globular and an intrinsically disordered). PMID:22760320

  14. Size and DNA distributions of electrophoretically separated cultured human kidney cells

    NASA Technical Reports Server (NTRS)

    Kunze, M. E.; Plank, L. D.; Todd, P. W.

    1985-01-01

    Electrophoretic purification of purifying cultured cells according to function presumes that the size of cycle phase of a cell is not an overriding determinant of its electrophoretic velocity in an electrophoretic separator. The size distributions and DNA distributions of fractions of cells purified by density gradient electrophoresis were determined. No systematic dependence of electrophoretic migration upward in a density gradient column upon either size or DNA content were found. It was found that human leukemia cell populations, which are more uniform function and found in all phases of the cell cycle during exponential growth, separated on a vertical sensity gradient electrophoresis column according to their size, which is shown to be strictly cell cycle dependent.

  15. Improved design of electrophoretic equipment for rapid sickle-cell-anemia screening

    NASA Technical Reports Server (NTRS)

    Reddick, J. M.; Hirsch, I.

    1974-01-01

    Effective mass screening may be accomplished by modifying existing electrophoretic equipment in conjunction with multisample applicator used with cellulose-acetate-matrix test paper. Using this method, approximately 20 to 25 samples can undergo electrophoresis in 5 to 6 minutes.

  16. Alteration of the electrophoretic mobility of human peripheral blood mononuclear cells following treatment with dimethyl sulfoxide

    SciTech Connect

    Skrabut, E.M.; Catsimpoolas, N.; Kurtz, S.R.; Griffith, A.L.; Valeri, C.R.

    1983-12-01

    Studies have been conducted to determine the effects of DMSO and freezing on the electrophoretic distribution of peripheral blood mononuclear cells. Sodium (/sup 51/Cr)chromate was used to label the cells, and the distributions of cell number and cell-associated radioactivity were determined. Cells treated with DMSO had a narrower distribution of electrophoretic mobilities when compared with those not treated. DMSO-treated cells also demonstrated a more homogeneous distribution of radioactivity relative to the cell distribution than did the nontreated cells. The freezing of DMSO-treated cells did not result in any additional alteration of electrophoretic pattern compared to DMSO treatment alone. Analysis by linear categorization techniques indicated that the DMSO-treated and nontreated cells were completely distinguished by their electrophoretic behavior.

  17. A model for electrophoretic transport of charged particles through membrane before steady state

    NASA Astrophysics Data System (ADS)

    de Souza, Tatiana Miranda; Fragoso, Viviane Muniz da Silva; Cruz, Frederico Alan de Oliveira

    2015-12-01

    In this paper, we are presenting a model for electrophoretic motion of a charged particle through the membrane before it reaches the steady state, based on concepts of Physics. Some results from analysis of the model are discussed.

  18. INFLUENCE OF BORATE BUFFERS ON THE ELECTROPHORETIC BEHAVIOR OF HUMIC SUBSTANCES IN CAPILLARY ZONE ELECTROPHORESIS

    EPA Science Inventory

    The influence of tetrahydroxyborate ions on the electrophoretic mobility of humic acids was evaluated by capillary electrophoresis (CE). Depending on the molarity of borate ions in the separation buffer, the humic acids exhibit electropherograms with sharp peaks consistently exte...

  19. AC electrophoretic deposition of organic-inorganic composite coatings.

    PubMed

    Yoshioka, T; Chávez-Valdez, A; Roether, J A; Schubert, D W; Boccaccini, A R

    2013-02-15

    Alternating current electrophoretic deposition (AC-EPD) of polyacrylic acid (PAA)-titanium oxide (TiO(2)) nanoparticle composites on stainless steel electrodes was investigated in basic aqueous solution. AC square wave with duty cycle of 80% was applied at a frequency of 1 kHz. FTIR-ATR spectra showed that both AC and direct current (DC) EPD successfully deposited PAA-TiO(2) composites. The deposition rate using AC-EPD was lower than that obtained in direct current DC-EPD. However, the microstructure and surface morphology of the deposited composite coatings were different depending on the type of electric field applied. AC-EPD applied for not more than 5 min led to smooth films without bubble formation, while DC-EPD for 1 min or more showed deposits with microstructural defects possibly as result of water electrolysis. AC-EPD was thus for the first time demonstrated to be a suitable technique to deposit organic-inorganic composite coatings from aqueous suspensions, showing that applying a square wave and frequency of 1 kHz leads to uniform PAA-TiO(2) composite coatings on conductive materials. PMID:23218240

  20. Integrated Microfluidic Isolation of Aptamers Using Electrophoretic Oligonucleotide Manipulation.

    PubMed

    Kim, Jinho; Olsen, Timothy R; Zhu, Jing; Hilton, John P; Yang, Kyung-Ae; Pei, Renjun; Stojanovic, Milan N; Lin, Qiao

    2016-01-01

    We present a microfluidic approach to integrated isolation of DNA aptamers via systematic evolution of ligands by exponential enrichment (SELEX). The approach employs a microbead-based protocol for the processes of affinity selection and amplification of target-binding oligonucleotides, and an electrophoretic DNA manipulation scheme for the coupling of these processes, which are required to occur in different buffers. This achieves the full microfluidic integration of SELEX, thereby enabling highly efficient isolation of aptamers in drastically reduced times and with minimized consumption of biological material. The approach as such also offers broad target applicability by allowing selection of aptamers with respect to targets that are either surface-immobilized or solution-borne, potentially allowing aptamers to be developed as readily available affinity reagents for a wide range of targets. We demonstrate the utility of this approach on two different procedures, respectively for isolating aptamers against a surface-immobilized protein (immunoglobulin E) and a solution-phase small molecule (bisboronic acid in the presence of glucose). In both cases aptamer candidates were isolated in three rounds of SELEX within a total process time of approximately 10 hours. PMID:27217242

  1. Integrated Microfluidic Isolation of Aptamers Using Electrophoretic Oligonucleotide Manipulation

    PubMed Central

    Kim, Jinho; Olsen, Timothy R.; Zhu, Jing; Hilton, John P.; Yang, Kyung-Ae; Pei, Renjun; Stojanovic, Milan N.; Lin, Qiao

    2016-01-01

    We present a microfluidic approach to integrated isolation of DNA aptamers via systematic evolution of ligands by exponential enrichment (SELEX). The approach employs a microbead-based protocol for the processes of affinity selection and amplification of target-binding oligonucleotides, and an electrophoretic DNA manipulation scheme for the coupling of these processes, which are required to occur in different buffers. This achieves the full microfluidic integration of SELEX, thereby enabling highly efficient isolation of aptamers in drastically reduced times and with minimized consumption of biological material. The approach as such also offers broad target applicability by allowing selection of aptamers with respect to targets that are either surface-immobilized or solution-borne, potentially allowing aptamers to be developed as readily available affinity reagents for a wide range of targets. We demonstrate the utility of this approach on two different procedures, respectively for isolating aptamers against a surface-immobilized protein (immunoglobulin E) and a solution-phase small molecule (bisboronic acid in the presence of glucose). In both cases aptamer candidates were isolated in three rounds of SELEX within a total process time of approximately 10 hours. PMID:27217242

  2. Electrophoretic mobility patterns of collagen following laser welding

    NASA Astrophysics Data System (ADS)

    Bass, Lawrence S.; Moazami, Nader; Pocsidio, Joanne O.; Oz, Mehmet C.; LoGerfo, Paul; Treat, Michael R.

    1991-06-01

    Clinical application of laser vascular anastomosis in inhibited by a lack of understanding of its mechanism. Whether tissue fusion results from covalent or non-covalent bonding of collagen and other structural proteins is unknown. We compared electrophoretic mobility of collagen in laser treated and untreated specimens of rat tail tendon (>90% type I collagen) and rabbit aorta. Welding was performed, using tissue shrinkage as the clinical endpoint, using the 808 nm diode laser (power density 14 watts/cm2) and topical indocyanine green dye (max absorption 805 nm). Collagen was extracted with 8 M urea (denaturing), 0.5 M acetic acid (non-denaturing) and acetic acid/pepsin (cleaves non- helical protein). Mobility patterns on gel electrophoresis (SDS-PAGE) after urea or acetic acid extraction were identical in the lasered and control tendon and vessel (confirmed by optical densitometry), revealing no evidence of formation of novel covalent bonds. Alpha and beta band intensity was diminished in pepsin incubated lasered specimens compared with controls (optical density ratio 0.00 +/- 9 tendon, 0.65 +/- 0.12 aorta), indicating the presence of denatured collagen. With the laser parameters used, collagen is denatured without formation of covalent bonds, suggesting that non-covalent interaction between denatured collagen molecules may be responsible for the weld. Based on this mechanism, welding parameters can be chosen which produce collagen denaturation without cell death.

  3. Open source simulation tool for electrophoretic stacking, focusing, and separation.

    PubMed

    Bercovici, Moran; Lele, Sanjiva K; Santiago, Juan G

    2009-02-01

    We present the development, formulation, and performance of a new simulation tool for electrophoretic preconcentration and separation processes such as capillary electrophoresis, isotachophoresis, and field amplified sample stacking. The code solves the one-dimensional transient advection-diffusion equations for multiple multivalent weak electrolytes (including ampholytes) and includes a model for pressure-driven flow and Taylor-Aris dispersion. The code uses a new approach for the discretization of the equations, consisting of a high resolution compact scheme which is combined with an adaptive grid algorithm. We show that this combination allows for accurate resolution of sharp concentration gradients at high electric fields, while at the same time significantly reducing the computational time. We demonstrate smooth, stable, and accurate solutions at current densities as high as 5000A/m(2) using only 300 grid points, and a 75-fold reduction in computational time compared with equivalent uniform grid techniques. The code is available as an open source for free at http://microfluidics.stanford.edu. PMID:19124132

  4. Integrated Microfluidic Isolation of Aptamers Using Electrophoretic Oligonucleotide Manipulation

    NASA Astrophysics Data System (ADS)

    Kim, Jinho; Olsen, Timothy R.; Zhu, Jing; Hilton, John P.; Yang, Kyung-Ae; Pei, Renjun; Stojanovic, Milan N.; Lin, Qiao

    2016-05-01

    We present a microfluidic approach to integrated isolation of DNA aptamers via systematic evolution of ligands by exponential enrichment (SELEX). The approach employs a microbead-based protocol for the processes of affinity selection and amplification of target-binding oligonucleotides, and an electrophoretic DNA manipulation scheme for the coupling of these processes, which are required to occur in different buffers. This achieves the full microfluidic integration of SELEX, thereby enabling highly efficient isolation of aptamers in drastically reduced times and with minimized consumption of biological material. The approach as such also offers broad target applicability by allowing selection of aptamers with respect to targets that are either surface-immobilized or solution-borne, potentially allowing aptamers to be developed as readily available affinity reagents for a wide range of targets. We demonstrate the utility of this approach on two different procedures, respectively for isolating aptamers against a surface-immobilized protein (immunoglobulin E) and a solution-phase small molecule (bisboronic acid in the presence of glucose). In both cases aptamer candidates were isolated in three rounds of SELEX within a total process time of approximately 10 hours.

  5. Origami paper-based fluidic batteries for portable electrophoretic devices.

    PubMed

    Chen, Sung-Sheng; Hu, Chih-Wei; Yu, I-Fan; Liao, Ying-Chih; Yang, Jing-Tang

    2014-06-21

    A manufacturing approach for paper-based fluidic batteries was developed based on the origami principle (three-dimension paper folding). Microfluidic channels were first created on a filter paper by a wax-printing method. Copper and aluminium sheets were then glued onto the paper as electrodes for the redox reaction. After the addition of copper sulphate and aluminium chloride, commonly available cellophane paper was attached as a membrane to separate the two electrodes. The resulting planar paper sheets were then folded into three-dimensional structures and compiled as a single battery with glue. The two half reactions (Al/Al(3+) and Cu/Cu(2+)) in the folded batteries provided an open-circuit potential from 0.82 V (one cell) to 5.0 V (eight cells in series) depending on the origami design. The prepared battery can provide a stable current of 500 μA and can light a regular LED for more than 65 min. These paper-based fluidic batteries in a set can also be compiled into a portable power bank to provide electric power for many electric or biomedical applications, such as LED lights and electrophoretic devices, as we report here. PMID:24811036

  6. Interfacial bond strength of electrophoretically deposited hydroxyapatite coatings on metals.

    PubMed

    Wei, M; Ruys, A J; Swain, M V; Kim, S H; Milthorpe, B K; Sorrell, C C

    1999-07-01

    Hydroxyapatite (HAp) coatings were deposited onto substrates of metal biomaterials (Ti, Ti6Al4V, and 316L stainless steel) by electrophoretic deposition (EPD). Only ultra-high surface area HAp powder, prepared by the metathesis method 10Ca(NO3)2 + 6(NH4)2HPO4 + 8NH4OH), could produce dense coatings when sintered at 875-1000degreesC. Single EPD coatings cracked during sintering owing to the 15-18% sintering shrinkage, but the HAp did not decompose. The use of dual coatings (coat, sinter, coat, sinter) resolved the cracking problem. Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) inspection revealed that the second coating filled in the "valleys" in the cracks of the first coating. The interfacial shear strength of the dual coatings was found, by ASTM F1044-87, to be approximately 12 MPa on a titanium substrate and approximately 22 MPa on 316L stainless steel, comparing quite favorably with the 34 MPa benchmark (the shear strength of bovine cortical bone was found to be 34 MPa). Stainless steel gave the better result since -316L (20.5 microm mK(-1)) > alpha-HAp (approximately 14 microm mK(-1)), resulting in residual compressive stresses in the coating, whereas alpha-titanium (approximately 10.3 microm mK(-1)) < alpha-HAp, resulting in residual tensile stresses in the coating. PMID:15348125

  7. Electrophoretic assembly of organic molecules and composites for electrochemical supercapacitors.

    PubMed

    Su, Y; Zhitomirsky, I

    2013-02-15

    Electrophoretic deposition (EPD) method has been developed for the fabrication of 1-pyrenebutyric acid (PBH) films from aqueous solutions. The films can be deposited at constant voltage or potentiodynamic conditions. The method allowed the formation of 0.1-2 μm thick films, containing needle-shape PBH particles. The deposition mechanism involved the electrophoresis, pH decrease at the anode surface, charge neutralization and formation of insoluble PBH films. The film morphology and shape of the PBH particles are controlled by the π-π stacking mechanism of the polyaromatic PBH molecules. The important finding was the possibility of controlled EPD of multiwalled carbon nanotubes (MWCNTs) using PBH as a charging, dispersing and film forming agent. It was found that at low voltages or low PBH concentrations the deposits contained mainly MWCNT. The increase in the deposition voltage or/and PBH concentration resulted in co-deposition of MWCNT and needle-shape PBH particles. The new approach to the deposition of MWCNT was used for the fabrication of composite MnO(2)-MWCNT films for electrodes of electrochemical supercapacitors, which showed a specific capacitance of 250 F g(-1). The EPD method developed in this investigation paves the way for the deposition of other small organic molecules and composites and their applications in new materials and devices, utilizing functional properties of the organic molecules, CNT, and other advanced materials. PMID:23141761

  8. Polyacrylamide medium for the electrophoretic separation of biomolecules

    DOEpatents

    Madabhushi, Ramakrishna S.; Gammon, Stuart A.

    2003-11-11

    A polyacryalmide medium for the electrophoretic separation of biomolecules. The polyacryalmide medium comprises high molecular weight polyacrylamides (PAAm) having a viscosity average molecular weight (M.sub.v) of about 675-725 kDa were synthesized by conventional red-ox polymerization technique. Using this separation medium, capillary electrophoresis of BigDye DNA sequencing standard was performed. A single base resolution of .about.725 bases was achieved in .about.60 minute in a non-covalently coated capillary of 50 .mu.m i.d., 40 cm effective length, and a filed of 160 V/cm at 40.degree. C. The resolution achieved with this formulation to separate DNA under identical conditions is much superior (725 bases vs. 625 bases) and faster (60 min. vs. 75 min.) to the commercially available PAAm, such as supplied by Amersham. The formulation method employed here to synthesize PAAm is straight-forward, simple and does not require cumbersome methods such as emulsion polymerizaiton in order to achieve very high molecular weights. Also, the formulation here does not require separation of PAAm from the reaction mixture prior to reconstituting the polymer to a final concentration. Furthermore, the formulation here is prepared from a single average mol. wt. PAAm as opposed to the mixture of two different average mo. wt. PAAm previously required to achieve high resolution.

  9. Improvement of electrophoretic enantioseparation of amlodipine by polybrene.

    PubMed

    Zandkarimi, Majid; Shafaati, Alireza; Foroutan, Sayyed Mohsen; A Lucy, Charles

    2012-01-01

    In chiral and non-chiral electrophoretic resolution of basic drugs, adsorption of analytes to negatively charged capillary wall could lead to poor repeatability of migration time and peak area. In addition, chiral resolutions of basic drugs are commonly performed in low pH buffers. Therefore, longer analysis time due to suppression of electroosmotic flow (EOF) is another dilemma. In this work the improvement effect of polybrene (PB), a cationic polymer, on chiral separation of a model basic drug, amlodipine (AML), was investigated. PB both as a semi-permanent coating agent and as an additive in the running buffer was utilized. Better results were obtained with PB as a buffer additive. Compare to untreated bare silica without using PB in running buffer, addition of 0.0005% PB buffer decreased analysis time downed to 3 folds; efficiency improved up to 5 folds; limit of detection (LOD) and limit of quantification (LOQ) downed to 8 folds and within-day migration time and peak area repeatabilities, in terms of relative standard deviations (RSD) downed to 5 and 20 folds, respectively. PMID:25317194

  10. Improvement of Electrophoretic Enantioseparation of Amlodipine by Polybrene

    PubMed Central

    Zandkarimi, Majid; Shafaati, Alireza; Foroutan, Sayyed Mohsen; A. Lucy, Charles

    2012-01-01

    In chiral and non-chiral electrophoretic resolution of basic drugs, adsorption of analytes to negatively charged capillary wall could lead to poor repeatability of migration time and peak area. In addition, chiral resolutions of basic drugs are commonly performed in low pH buffers. Therefore, longer analysis time due to suppression of electroosmotic flow (EOF) is another dilemma. In this work the improvement effect of polybrene (PB), a cationic polymer, on chiral separation of a model basic drug, amlodipine (AML), was investigated. PB both as a semi-permanent coating agent and as an additive in the running buffer was utilized. Better results were obtained with PB as a buffer additive. Compare to untreated bare silica without using PB in running buffer, addition of 0.0005% PB buffer decreased analysis time downed to 3 folds; efficiency improved up to 5 folds; limit of detection (LOD) and limit of quantification (LOQ) downed to 8 folds and within-day migration time and peak area repeatabilities, in terms of relative standard deviations (RSD) downed to 5 and 20 folds, respectively. PMID:25317194

  11. Fabrication of Electrophoretic Display Driven by Membrane Switch Array

    NASA Astrophysics Data System (ADS)

    Senda, Kazuo; Usui, Hiroaki

    2010-04-01

    Electrophoretic devices (EPDs) and organic light-emitting diodes (OLEDs) have potential application in a large-area flexible displays, such as digital signage. For this purpose, a new backplane is capable of driving a large unit is required instead of thin-film transistors. In this paper we describe the fabrication of a membrane switch array suitable for driving large-scale flat-panel displays. An array of membrane switches was prepared using flexible printed circuit (FPC) technology of polyimide films, by combining low-temperature processes of lamination and copper electroplating methods. An array of 256 matrix switches with a pixel size of 7 mm2 was prepared to drive the EPD front panel. The switches were driven at a voltage of about 40 V and a frequency of 10 Hz. The operation characteristics agreed well with the result of the theoretical calculation. The calculation also suggested that driving voltage can be lowered by increasing pixel size. The contact resistance of the membrane switch was as low as 0.2 Ω, which implies the wide applicability of this device for driving a variety of elements.

  12. Electrophoretic deposition of composite hydroxyapatite-silica-chitosan coatings

    SciTech Connect

    Grandfield, K.; Zhitomirsky, I.

    2008-01-15

    Electrophoretic deposition (EPD) method has been developed for the fabrication of nanocomposite silica-chitosan coatings. Cathodic deposits were obtained on various conductive substrates using suspensions of silica nanoparticles in a mixed ethanol-water solvent, containing dissolved chitosan. Co-deposition of silica and hydroxyapatite (HA) nanoparticles resulted in the fabrication of HA-silica-chitosan coatings. The deposition yield has been studied at a constant voltage mode at various deposition durations. The method enabled the formation of coatings of different thickness in the range of up to 100 {mu}m. Deposit composition, microstructure and porosity can be varied by variation of HA and silica concentration in the suspensions. It was demonstrated that EPD can be used for the fabrication of HA-silica-chitosan coatings of graded composition and laminates. The method enabled the deposition of coatings containing layers of silica-chitosan and HA-chitosan nanocomposites using suspensions with different HA and silica content. Obtained coatings were studied by X-ray diffraction, thermogravimetric and differential thermal analysis, scanning electron microscopy and energy dispersive spectroscopy. The mechanism of deposition is discussed.

  13. Solubilization and electrophoretic characterization of select edible nut seed proteins.

    PubMed

    Sathe, Shridhar K; Venkatachalam, Mahesh; Sharma, Girdhari M; Kshirsagar, Harshal H; Teuber, Suzanne S; Roux, Kenneth H

    2009-09-01

    The solubility of almond, Brazil nut, cashew nut, hazelnut, macadamia, pecan, pine nut, pistachio, walnut, and peanut proteins in several aqueous solvents was qualitatively and quantitatively assessed. In addition, the effects of extraction time and ionic strength on protein solubility were also investigated. Electrophoresis and protein determination (Lowry, Bradford, and micro-Kjeldahl) methods were used for qualitative and quantitative assessment of proteins, respectively. Depending on the seed, buffer type and ionic strength significantly affected protein solubility. The results suggest that buffered sodium borate (BSB; 0.1 M H(3)BO(3), 0.025 M Na(2)B(4)O(7), 0.075 M NaCl, pH 8.45) optimally solubilizes nut seed proteins. Qualitative differences in seed protein electrophoretic profiles were revealed. For a specific seed type, these differences were dependent on the solvent(s) used to solubilize the seed proteins. SDS-PAGE results suggest the polypeptide molecular mass range for the tree nut seed proteins to be 3-100 kDa. The results of native IEF suggested that the proteins were mainly acidic, with a pI range from >4.5 to <7.0. Western immunoblotting experiments indicated that rabbit polyclonal antibodies recognized substantially the same polypeptides as those recognized by the corresponding pooled patient sera IgE. PMID:19655801

  14. Electrophoretic deposition of tannic acid-polypyrrolidone films and composites.

    PubMed

    Luo, Dan; Zhang, Tianshi; Zhitomirsky, Igor

    2016-05-01

    Thin films of polyvinylpyrrolidone (PVP)-tannic acid (TA) complexes were prepared by a conceptually new strategy, based on electrophoretic deposition (EPD). Proof of concept investigations involved the analysis of the deposition yield, FTIR and UV-vis spectroscopy of the deposited material, and electron microscopy studies. The analysis of the deposition mechanism indicated that the limitations of the EPD in the deposition of small phenolic molecules, such as TA, and electrically neutral polymers, similar to PVP, containing hydrogen-accepting carbonyl groups, can be avoided. The remarkable adsorption properties of TA and film forming properties of the PVP-TA complexes allowed for the EPD of materials of different types, such as huntite mineral platelets and hydrotalcite clay particles, TiO2 and MnO2 oxide nanoparticles, multiwalled carbon nanotubes, TiN and Pd nanoparticles. Moreover, PVP-TA complexes were used for the co-deposition of different materials and formation of composite films. In another approach, TA was used as a capping agent for the hydrothermal synthesis of ZnO nanorods, which were then deposited by EPD using PVP-TA complexes. The fundamental adsorption and interaction mechanisms of TA involved chelation of metal atoms on particle surfaces with galloyl groups, π-π interactions and hydrogen bonding. The films prepared by EPD can be used for various applications, utilizing functional properties of TA, PVP, inorganic and organic materials of different types and their composites. PMID:26878711

  15. Electrophoretic mobilities of cultured human embryonic kidney cells in various buffers

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Data on the electrophoretic mobility distributions of cells in the new D-1 buffer and the interlaboratory standardization of urokinase assay methods are presented. A table of cell strains and recent data on cell dispersal methods are also included. It was decided that glycerol in A-1 electrophoretic mobility data on cultured human embryonic kidney cells subjected to electrophoresis in this buffer. The buffer composition is presented.

  16. Effect of passage number on electrophoretic mobility distributions of cultured human embryonic kidney cells

    NASA Technical Reports Server (NTRS)

    Kunze, M. E.

    1985-01-01

    A systematic investigation was undertaken to characterize population shifts that occur in cultured human embryonic kidney cells as a function of passage number in vitro after original explantation. This approach to cell population shift analysis follows the suggestion of Mehreshi, Klein and Revesz that perturbed cell populations can be characterized by electrophoretic mobility distributions if they contain subpopulations with different electrophoretic mobilities. It was shown that this is the case with early passage cultured human embryo cells.

  17. Palladium(II) complex with S-allyl- L-cysteine: New solid-state NMR spectroscopic measurements, molecular modeling and antibacterial assays

    NASA Astrophysics Data System (ADS)

    Spera, Marcelle B. M.; Quintão, Frederico A.; Ferraresi, Diego K. D.; Lustri, Wilton R.; Magalhães, Alviclér; Formiga, André L. B.; Corbi, Pedro P.

    2011-01-01

    Nuclear magnetic resonance studies, molecular modeling and antibacterial assays of the palladium(II) complex with S-allyl- L-cysteine (deoxyalliin) are presented. Studies based on solid and solution 13C and 15N nuclear magnetic resonance (NMR) spectroscopy confirmed that the palladium(II) complex preserved the same structural arrangement in both states, with no modifications on coordination sphere when dissolved in water. Density functional theory (DFT) studies stated that the trans isomer is the most stable one. Antibacterial activities of S-allyl- L-cysteine and its palladium(II) complex were evaluated by antibiogram assays using the disc diffusion method. The palladium(II) complex showed an effective antibacterial activity against S taphylococcus aureus (Gram-positive), Escherichia coli and Pseudomonas aeruginosa (Gram-negative) bacterial cells.

  18. Resolution and measurement of heteronuclear dipolar couplings of a noncrystalline protein immobilized in a biological supramolecular assembly by proton-detected MAS solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Park, Sang Ho; Yang, Chen; Opella, Stanley J.; Mueller, Leonard J.

    2013-12-01

    Two-dimensional 15N chemical shift/1H chemical shift and three-dimensional 1H-15N dipolar coupling/15N chemical shift/1H chemical shift MAS solid-state NMR correlation spectra of the filamentous bacteriophage Pf1 major coat protein show single-site resolution in noncrystalline, intact-phage preparations. The high sensitivity and resolution result from 1H detection at 600 MHz under 50 kHz magic angle spinning using ∼0.5 mg of perdeuterated and uniformly 15N-labeled protein in which the exchangeable amide sites are partially or completely back-exchanged (reprotonated). Notably, the heteronuclear 1H-15N dipolar coupling frequency dimension is shown to select among 15N resonances, which will be useful in structural studies of larger proteins where the resonances exhibit a high degree of overlap in multidimensional chemical shift correlation spectra.

  19. Probe for high resolution NMR with sample reorientation

    DOEpatents

    Pines, A.; Samoson, A.

    1990-02-06

    An improved NMR probe and method are described which substantially improve the resolution of NMR measurements made on powdered or amorphous or otherwise orientationally disordered samples. The apparatus mechanically varies the orientation of the sample such that the time average of two or more sets of spherical harmonic functions are zero. 8 figs.

  20. Probe for high resolution NMR with sample reorientation

    DOEpatents

    Pines, Alexander; Samoson, Ago

    1990-01-01

    An improved NMR probe and method are described which substantially improve the resolution of NMR measurements made on powdered or amorphous or otherwise orientationally disordered samples. The apparatus mechanically varies the orientation of the sample such that the time average of two or more sets of spherical harmonic functions are zero.

  1. Selective excitation enables assignment of proton resonances and (1)H-(1)H distance measurement in ultrafast magic angle spinning solid state NMR spectroscopy.

    PubMed

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2015-07-21

    Remarkable developments in ultrafast magic angle spinning (MAS) solid-state NMR spectroscopy enabled proton-based high-resolution multidimensional experiments on solids. To fully utilize the benefits rendered by proton-based ultrafast MAS experiments, assignment of (1)H resonances becomes absolutely necessary. Herein, we propose an approach to identify different proton peaks by using dipolar-coupled heteronuclei such as (13)C or (15)N. In this method, after the initial preparation of proton magnetization and cross-polarization to (13)C nuclei, transverse magnetization of desired (13)C nuclei is selectively prepared by using DANTE (Delays Alternating with Nutations for Tailored Excitation) sequence and then, it is transferred to bonded protons with a short-contact-time cross polarization. Our experimental results demonstrate that protons bonded to specific (13)C atoms can be identified and overlapping proton peaks can also be assigned. In contrast to the regular 2D HETCOR experiment, only a few 1D experiments are required for the complete assignment of peaks in the proton spectrum. Furthermore, the finite-pulse radio frequency driven recoupling sequence could be incorporated right after the selection of specific proton signals to monitor the intensity buildup for other proton signals. This enables the extraction of (1)H-(1)H distances between different pairs of protons. Therefore, we believe that the proposed method will greatly aid in fast assignment of peaks in proton spectra and will be useful in the development of proton-based multi-dimensional solid-state NMR experiments to study atomic-level resolution structure and dynamics of solids. PMID:26203019

  2. Selective excitation enables assignment of proton resonances and 1H-1H distance measurement in ultrafast magic angle spinning solid state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2015-07-01

    Remarkable developments in ultrafast magic angle spinning (MAS) solid-state NMR spectroscopy enabled proton-based high-resolution multidimensional experiments on solids. To fully utilize the benefits rendered by proton-based ultrafast MAS experiments, assignment of 1H resonances becomes absolutely necessary. Herein, we propose an approach to identify different proton peaks by using dipolar-coupled heteronuclei such as 13C or 15N. In this method, after the initial preparation of proton magnetization and cross-polarization to 13C nuclei, transverse magnetization of desired 13C nuclei is selectively prepared by using DANTE (Delays Alternating with Nutations for Tailored Excitation) sequence and then, it is transferred to bonded protons with a short-contact-time cross polarization. Our experimental results demonstrate that protons bonded to specific 13C atoms can be identified and overlapping proton peaks can also be assigned. In contrast to the regular 2D HETCOR experiment, only a few 1D experiments are required for the complete assignment of peaks in the proton spectrum. Furthermore, the finite-pulse radio frequency driven recoupling sequence could be incorporated right after the selection of specific proton signals to monitor the intensity buildup for other proton signals. This enables the extraction of 1H-1H distances between different pairs of protons. Therefore, we believe that the proposed method will greatly aid in fast assignment of peaks in proton spectra and will be useful in the development of proton-based multi-dimensional solid-state NMR experiments to study atomic-level resolution structure and dynamics of solids.

  3. Selective excitation enables assignment of proton resonances and {sup 1}H-{sup 1}H distance measurement in ultrafast magic angle spinning solid state NMR spectroscopy

    SciTech Connect

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2015-07-21

    Remarkable developments in ultrafast magic angle spinning (MAS) solid-state NMR spectroscopy enabled proton-based high-resolution multidimensional experiments on solids. To fully utilize the benefits rendered by proton-based ultrafast MAS experiments, assignment of {sup 1}H resonances becomes absolutely necessary. Herein, we propose an approach to identify different proton peaks by using dipolar-coupled heteronuclei such as {sup 13}C or {sup 15}N. In this method, after the initial preparation of proton magnetization and cross-polarization to {sup 13}C nuclei, transverse magnetization of desired {sup 13}C nuclei is selectively prepared by using DANTE (Delays Alternating with Nutations for Tailored Excitation) sequence and then, it is transferred to bonded protons with a short-contact-time cross polarization. Our experimental results demonstrate that protons bonded to specific {sup 13}C atoms can be identified and overlapping proton peaks can also be assigned. In contrast to the regular 2D HETCOR experiment, only a few 1D experiments are required for the complete assignment of peaks in the proton spectrum. Furthermore, the finite-pulse radio frequency driven recoupling sequence could be incorporated right after the selection of specific proton signals to monitor the intensity buildup for other proton signals. This enables the extraction of {sup 1}H-{sup 1}H distances between different pairs of protons. Therefore, we believe that the proposed method will greatly aid in fast assignment of peaks in proton spectra and will be useful in the development of proton-based multi-dimensional solid-state NMR experiments to study atomic-level resolution structure and dynamics of solids.

  4. Combining solid-state NMR spectroscopy with first-principles calculations - a guide to NMR crystallography.

    PubMed

    Ashbrook, Sharon E; McKay, David

    2016-06-01

    Recent advances in the application of first-principles calculations of NMR parameters to periodic systems have resulted in widespread interest in their use to support experimental measurement. Such calculations often play an important role in the emerging field of "NMR crystallography", where NMR spectroscopy is combined with techniques such as diffraction, to aid structure determination. Here, we discuss the current state-of-the-art for combining experiment and calculation in NMR spectroscopy, considering the basic theory behind the computational approaches and their practical application. We consider the issues associated with geometry optimisation and how the effects of temperature may be included in the calculation. The automated prediction of structural candidates and the treatment of disordered and dynamic solids are discussed. Finally, we consider the areas where further development is needed in this field and its potential future impact. PMID:27117884

  5. SQUID detected NMR in microtesla magnetic fields

    NASA Astrophysics Data System (ADS)

    Matlachov, Andrei N.; Volegov, Petr L.; Espy, Michelle A.; George, John S.; Kraus, Robert H.

    2004-09-01

    We have built an NMR system that employs a superconducting quantum interference device (SQUID) detector and operates in measurement fields of 2-25 μT. The system uses a pre-polarizing field from 4 to 30 mT generated by simple room-temperature wire-wound coils that are turned off during measurements. The instrument has an open geometry with samples located outside the cryostat at room-temperature. This removes constraints on sample size and allows us to obtain signals from living tissue. We have obtained 1H NMR spectra from a variety of samples including water, mineral oil, and a live frog. We also acquired gradient encoded free induction decay (FID) data from a water-plastic phantom in the μT regime, from which simple projection images were reconstructed. NMR signals from samples inside metallic containers have also been acquired. This is possible because the penetration skin depth is much greater at the low operating frequencies of this system than for conventional systems. Advantages to ultra-low field NMR measurements include lower susceptibility artifacts caused by high strength polarizing and measurement fields, and negligible line width broadening due to measurement field inhomogeneity, reducing the burden of producing highly homogeneous fields.

  6. Screening proteins for NMR suitability

    PubMed Central

    Yee, Adelinda A.; Semesi, Anthony; Garcia, Maite; Arrowsmith, Cheryl H.

    2014-01-01

    Summary NMR spectroscopy is an invaluable tool in structural genomics. Identification of protein samples that are amenable to structure determination by NMR spectroscopy requires efficient screening. Here, we describe how we prepare multiple samples in parallel and screen by NMR. The method described here is applicable to large structural genomics projects but can easily be scaled down for application to small structural biology projects since all the equipments used are those commonly found in any NMR structural biology laboratory. PMID:24590717

  7. Modern NMR Spectroscopy.

    ERIC Educational Resources Information Center

    Jelinski, Lynn W.

    1984-01-01

    Discusses direct chemical information that can be obtained from modern nuclear magnetic resonance (NMR) methods, concentrating on the types of problems that can be solved. Shows how selected methods provide information about polymers, bipolymers, biochemistry, small organic molecules, inorganic compounds, and compounds oriented in a magnetic…

  8. Enantiodiscrimination by NMR spectroscopy.

    PubMed

    Uccello-Barretta, Gloria; Balzano, Federica; Salvadori, Piero

    2006-01-01

    The analysis of enantiorecognition processes involves the detection of enantiomeric species as well as the study of chiral discrimination mechanisms. In both fields Nuclear Magnetic Resonance (NMR) spectroscopy plays a fundamental role, providing several tools, based on the use of suitable chiral auxiliaries, for observing distinct signals of enantiomers and for investigating the complexation phenomena involved in enantiodiscrimination processes. PMID:17100610

  9. Determination of sulfonylureas in cereal samples with electrophoretic method using ionic liquid with dispersed carbon nanotubes as electrophoretic buffer.

    PubMed

    Springer, Valeria H; Aprile, Francisco; Lista, Adriana G

    2014-01-15

    A capillary electrophoresis method to determine four sulfonylureas in grain samples was developed using 10mM of 1-butyl-3-methyl imidazolium tetrafluoroborate (bminBF4) as electrophoretic buffer solution. 2mgL(-1) of Surfactant Coated-Single Wall-Carbon Nanotubes (SC-SWCNTs) was added to the buffer solution to improve the resolution. In this way, the separation of nicosulfuron, ethoxysulfuron, sulfometuron methyl and chlorsulfuron was carried out in 16min without using organic solvents. A clean up-preconcentration procedure was done prior to inject the sample into the CE instrument, in order to achieve the established maximum residue limits (MRLs). So, the detection limits (LODs) for each analytes were between 16.8 and 26.6μgkg(-1). The relative standard deviations (RSDs) were in the range 1.9-6.7%. A recovery study using the so-called matrix matched calibration demonstrates that no matrix interferences were found throughout the determination. The recovery percentages were ranged between 80% and 113%. PMID:24054250

  10. Picoliter H-1 NMR Spectroscopy

    SciTech Connect

    Minard, Kevin R. ); Wind, Robert A. )

    2002-02-01

    A RF probe that fits inside the bore of a small gradient coil package is described for routine 1H-NMR microscopy measurements on small samples. The probe operates at 500 MHz and houses a 267-um-diameter solenoid transceiver. When used in three dimensional chemical shift imaging (3D-CSI) experiments, the measured signal-to-noise ratio (SNR) is shown to be within 20-30 percent of theoretical limits formulated by only considering the solenoid's resistive losses. This is illustrated using a 100-um-diameter globule of triacylglycerols ({approx}900mM) that may be an oocyte precursor in young Xenopus Laevis frogs, and water sample containing choline at a concentration often found in live cells ({approx}33mM). In chemical shift images generated using a few thousand scans, the choline methyl line is found to have an acceptable SNR in resolved from just 5 picoliters in the Xenopus globule. It is concluded that the probe's sensitivity is sufficient for performing 1H-NMR on picoliter-scale volumes in biological cells and tissues.

  11. Understanding NMR relaxometry of partially water-saturated rocks

    NASA Astrophysics Data System (ADS)

    Mohnke, O.; Jorand, R.; Nordlund, C.; Klitzsch, N.

    2015-06-01

    Nuclear magnetic resonance (NMR) relaxometry measurements are commonly used to characterize the storage and transport properties of water-saturated rocks. Estimations of these properties are based on the direct link of the initial NMR signal amplitude to porosity (water content) and of the NMR relaxation time to pore size. Herein, pore shapes are usually assumed to be spherical or cylindrical. However, the NMR response at partial water saturation for natural sediments and rocks may differ strongly from the responses calculated for spherical or cylindrical pores, because these pore shapes do not account for water menisci remaining in the corners of desaturated angular pores. Therefore, we consider a bundle of pores with triangular cross sections. We introduce analytical solutions of the NMR equations at partial saturation of these pores, which account for water menisci of desaturated pores. After developing equations that describe the water distribution inside the pores, we calculate the NMR response at partial saturation for imbibition and drainage based on the deduced water distributions. For this pore model, the NMR amplitudes and NMR relaxation times at partial water saturation strongly depend on pore shape, i.e., arising from the capillary pressure and pore shape-dependent water distribution in desaturated pores with triangular cross sections. Even so, the NMR relaxation time at full saturation only depends on the surface-to-volume ratio of the pore. Moreover, we show the qualitative agreement of the saturation-dependent relaxation-time distributions of our model with those observed for rocks and soils.

  12. Effect of nanodroplet ink concentration on switching response of reverse-emulsion electrophoretic displays

    NASA Astrophysics Data System (ADS)

    Wang, Winston K.; Cromer, Remy; Goedert, Michel; Mobed-Miremadi, Maryam; Lee, Sang-Joon J.

    2013-03-01

    Reverse-emulsion electrophoretic display (REED) technology is based on an electro-responsive ink comprised of self-assembled nanodroplets dispersed in a non-polar liquid. The dye-containing nanodroplets are selectively driven toward or away from the viewing plane by patterned electrodes that define distinct pixels. In this study, experimental measurements of relative luminance were conducted to determine how ink concentration affects display performance, especially with respect to image contrast and response time. The particle size distribution of the ink was determined by dynamic light scattering and corroborated by atomic force microscopy, with average size approximately 200 nm. Concentration levels of 100%, 50%, 37.5%, 25%, 18.8%, 12.5% were tested for luminance, and the highest contrast ratio was achieved at 25%. Ink concentration was observed to have little effect on switching time, with all cases reaching steady state within approximately 2 s. Spatial variability was measured by isolating 5 mm circular zones within each tested device, and the lowest variability in relative luminance was observed for 18.8% and 25% concentration levels. The experimental observations were compared to predicted behavior based on multiphysics simulation with diluted species transport and electrostatics. The experimental test devices exhibited behavior that was similar to the saturation effects predicted by simulation, accounting for steric effects.

  13. Electrophoretic pattern of Linguatula serrata larva isolated goat mesenteric lymph node.

    PubMed

    Youssefi, Mohammad Reza; Tabaripour, Rabeeh; Gerami, Abbas; Omrani, Vahid Fallah

    2016-06-01

    Linguatula serrata, one of the parasitic zoonoses, inhabits the canid and felid respiratory system. The parasite is tongue-shaped, lightly convex dorsally and flattened ventrally. Males measure 1.8-2 cm, while females measure 8-13 cm in length. Disease due to infection with this parasite in humans is more likely to cause pharyngitis, nausea and vomiting, sore and itchy throat, cough, phlegm and runny nose. Present study aimed to determine linguatula's larva somatic antigens in lymph nodes of infected goats and also reveal the major component of antigenic protein. To determine the electrophoretic pattern of L. serrata's larvae, 50 samples were taken from goat's referred to the slaughter house of Amol, Mazandaran, Iran. After performing SDS-PAGE on somatic antigens, 6 bands (19, 20, 36, 48, 75,100 KDa) were seen in which the 36, 48 and 75 KDa bands were more prominent. In conclusion, it is recommended to determine the most important antigenic protein of this parasite could be used an experimental model in infection up to determine the most significant component of this parasite's antigen and use of that in immunogenicity and detection of infection. PMID:27413296

  14. NMR studies of cation transport across membranes

    SciTech Connect

    Shochet, N.R.

    1985-01-01

    /sup 23/Na NMR Studies of cation transport across membranes were conducted both on model and biological membranes. Two ionophores, the carrier monensin and the channel-former gramicidin, were chosen to induce cation transport in large unilamellar phosphatidylcholine vesicles. The distinction between the NMR signals arising from the two sides of the membrane was achieved by the addition of an anionic paramagnetic shift reagent to the outer solution. The kinetics of the cation transport across the membrane was observed simultaneously monitoring the changes in the /sup 23/Na NMR signals of both compartments. Two mathematical models were developed for the estimation of the transport parameters of the monensin- and gramicidin-induced cation transport. The models were able to fit the experimental data very well. A new method for the estimation of the volume trapped inside the vesicles was developed. The method uses the relative areas of the intra- and extravesicular NMR signals arising from a suspension of vesicles bathed in the same medium they contain, as a measure for the relative volumes of these compartments. Sodium transport across biological membranes was studied by /sup 23/ NMR, using suspensions of cultured nerve cells. The sodium influx through voltage-gated channels was studied using the channel modifier batrachotoxin in combination with scorpion toxin.

  15. 13C NMR Metabolomics: INADEQUATE Network Analysis

    PubMed Central

    Clendinen, Chaevien S.; Pasquel, Christian; Ajredini, Ramadan; Edison, Arthur S.

    2015-01-01

    The many advantages of 13C NMR are often overshadowed by its intrinsically low sensitivity. Given that carbon makes up the backbone of most biologically relevant molecules, 13C NMR offers a straightforward measurement of these compounds. Two-dimensional 13C-13C correlation experiments like INADEQUATE (incredible natural abundance double quantum transfer experiment) are ideal for the structural elucidation of natural products and have great but untapped potential for metabolomics analysis. We demonstrate a new and semi-automated approach called INETA (INADEQUATE network analysis) for the untargeted analysis of INADEQUATE datasets using an in silico INADEQUATE database. We demonstrate this approach using isotopically labeled Caenorhabditis elegans mixtures. PMID:25932900

  16. Important parameters in semi-dry electrophoretic transfer.

    PubMed

    Jacobson, G; Kårsnäs, P

    1990-01-01

    The efficiency of semi-dry electrophoretic transfer after sodium dodecyl sulfate (SDS)-electrophoresis using PhastGel media was investigated in a model system using three isotope labelled proteins. To give a full picture of the blotting process the amount of protein present in the gel, membranes, and filter papers was determined after different transfer times. The influence of the transfer buffer, commonly used additives such as methanol and SDS, and several different immobilizing matrices was investigated. Soybean trypsin inhibitor, bovine serum albumin, and ferritin were used as model proteins to study the effect of size on transfer efficiency. Basically, all three stages of the blotting process decide the result; the elution of protein from the gel, the immobilization of protein to the membrane, and the loss of material from the membrane during transfer. A theoretical explanation for the observed poor binding to a second membrane is discussed. Our results show that the buffer composition has little influence on the efficiency of transfer from the gel, but can be significant to the binding capacity of the membrane. In all experiments performed, there was never one moment during the transfer when all protein was eluted from the gel and simultaneously still bound to the membrane. The highest recovery in the membrane was obtained at different time intervals for different proteins. This indicates that quantitative transfer procedures cannot be generalized. However, obtaining an optimal method for reliable quantification of a specific protein or group of proteins is possible. For general protein staining of nitrocellulose and polyvinylidene difluoride membranes, a highly sensitive silver staining method requiring only 15 min has been used. PMID:1690643

  17. Probing surface interactions by combining NMR cryoporometry and NMR relaxometry

    NASA Astrophysics Data System (ADS)

    Mitchell, J.; Stark, S. C.; Strange, J. H.

    2005-06-01

    To further expand on the understanding of surface interactions at the liquid/solid interface on pore walls, the nuclear magnetic resonance (NMR) techniques of cryoporometry and relaxometry have been combined. The combination of these techniques allows variations in NMR relaxation parameters from pore surface to volume ratio changes and from surface interaction changes to be distinguished. By studying a range of sol-gel silicas from two different sources, it was noted that the relaxation time measurements were not consistent with the pore diameters determined by cryoporometry and N2 gas adsorption. Instead distinctly different relaxivity constants were determined for each absorbate in each of the two brands of silica. It was clear that the relaxation times were modified by more than just the pore geometry. Independent experiments on the two brands of silica suggested that the relaxometry results were heavily influenced by the concentration of paramagnetic relaxation centres in the silica gels. The strength of surface interaction, and hence surface affinity, was seen to depend on the liquid in the pores. Using this difference in surface affinities, binary mixtures of alkanes placed in sol-gel silicas were separated via preferential absorption and their components identified using cryoporometry, whereas the components could not be distinguished in the bulk liquid.

  18. New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella thermoaceticum metabolic profiles

    SciTech Connect

    Xue, Junfeng; Isern, Nancy G.; Ewing, R James; Liyu, Andrey V.; Sears, Jesse A.; Knapp, Harlan; Iversen, Jens; Sisk, Daniel R.; Ahring, Birgitte K.; Majors, Paul D.

    2014-06-20

    An in-situ nuclear magnetic resonance (NMR) bioreactor was developed and employed to monitor microbial metabolism under batch-growth conditions in real time. We selected Moorella thermoacetica ATCC 49707 as a test case. M. thermoacetica (formerly Clostridium thermoaceticum) is a strictly anaerobic, thermophilic, acetogenic, gram-positive bacterium with potential for industrial production of chemicals. The metabolic profiles of M. thermoacetica were characterized during growth in batch mode on xylose (a component of lignocellulosic biomass) using the new generation NMR bioreactor in combination with high-resolution, high sensitivity NMR (HR-NMR) spectroscopy. In-situ NMR measurements were performed using water-suppressed H-1 NMR spectroscopy at an NMR frequency of 500 MHz, and aliquots of the bioreactor contents were taken for 600 MHz HR-NMR spectroscopy at specific intervals to confirm metabolite identifications and expand metabolite coverage. M. thermoacetica demonstrated the metabolic potential to produce formate, ethanol and methanol from xylose, in addition to its known capability of producing acetic acid. Real-time monitoring of bioreactor conditions showed a temporary pH decrease, with a concomitant increase in formic acid during exponential growth. Fermentation experiments performed outside of the magnet showed that the strong magnetic field employed for NMR detection did not significantly affect cell metabolism. Use of the in-situ NMR bioreactor facilitated monitoring of the fermentation process in real time, enabling identification of intermediate and end-point metabolites and their correlation with pH and biomass produced during culture growth. Real-time monitoring of culture metabolism using the NMR bioreactor in combination with the HR-NMR spectroscopy will allow optimization of the metabolism of microorganisms producing valuable bioproducts.

  19. Solubilization of Minerals by Bacteria: Electrophoretic Mobility of Thiobacillus ferrooxidans in the Presence of Iron, Pyrite, and Sulfur

    PubMed Central

    Blake, Robert C.; Shute, Elizabeth A.; Howard, Gary T.

    1994-01-01

    Thiobacillus ferroxidans is an obligate acidophile that respires aerobically on pyrite, elemental sulfur, or soluble ferrous ions. The electrophoretic mobility of the bacterium was determined by laser Doppler velocimetry under physiological conditions. When grown on pyrite or ferrous ions, washed cells were negatively charged at pH 2.0. The density of the negative charge depended on whether the conjugate base was sulfate, perchlorate, chloride, or nitrate. The addition of ferric ions shifted the net charge on the surface asymptotically to a positive value. When grown on elemental sulfur, washed cells were close to their isoelectric point at pH 2.0. Both pyrite and colloidal sulfur were negatively charged under the same conditions. The electrical double layer around the bacterial cells under physiological conditions exerted minimal electrostatic repulsion in possible interactions between the cell and either of its charged insoluble substrates. When Thiobacillus ferrooxidans was mixed with either pyrite or colloidal sulfur at pH 2.0, the mobility spectra of the free components disappeared with time to be replaced with a new colloidal particle whose electrophoretic properties were intermediate between those of the starting components. This new particle had the charge and size properties anticipated for a complex between the bacterium and its insoluble substrates. The utility of such measurements for the study of the interactions of chemolithotrophic bacteria with their insoluble substrates is discussed. Images PMID:16349387

  20. Electrophoretic capture and detection of nanoparticles at the opening of a membrane pore using scanning electrochemical microscopy.

    PubMed

    Lee, Sungwon; Zhang, Yanhui; White, Henry S; Harrell, C Chad; Martin, Charles R

    2004-10-15

    Stochastic electrophoretic capture of individual nanometer-scale particles at the small opening of a conically shaped nanopore in a synthetic membrane is described. Particle capture is sensed using a scanning electrochemical microscope (SECM) to measure the decrease in the transport rate of a redox-active molecule through the pore. The SECM tip is positioned at the larger backside opening of pore and used to amperometrically monitor the transport rate prior, during, and after particle capture. Following capture, the particle is released by electrophoretically driving it out of the pore opening and back into the solution. The capture and release method is demonstrated by detection of charged polystyrene spheres (43-150-nm diameter) using a polycarbonate membrane with conically shaped pores, the small opening of the pore having a diameter of 60 nm. The inverse of the time to capture polystyrene spheres increases with particle concentration over the range 10(8)-10(10) particles/mL. Selective detection based on nanoparticle charge and size is also demonstrated. A quantitative theoretical description of the rate of particle capture is presented, and the physical mechanism of particle capture, based on the balance of electrostatic and entropic forces, is considered. PMID:15481960

  1. Improved Bacterial and Viral Recoveries from 'Complex' Samples using Electrophoretically Assisted Acoustic Focusing

    SciTech Connect

    Ness, K; Rose, K; Jung, B; Fisher, K; Mariella, Jr., R P

    2008-03-27

    Automated front-end sample preparation technologies can significantly enhance the sensitivity and reliability of biodetection assays [1]. We are developing advanced sample preparation technologies for biowarfare detection and medical point-of-care diagnostics using microfluidic systems with continuous sample processing capabilities. Here we report an electrophoretically assisted acoustic focusing technique to rapidly extract and enrich viral and bacterial loads from 'complex samples', applied in this case to human nasopharyngeal samples as well as simplified surrogates. The acoustic forces capture and remove large particles (> 2 {micro}m) such as host cells, debris, dust, and pollen from the sample. We simultaneously apply an electric field transverse to the flow direction to transport small ({le} 2 {micro}m), negatively-charged analytes into a separate purified recovery fluid using a modified H-filter configuration [Micronics US Patent 5,716,852]. Hunter and O'Brien combined transverse electrophoresis and acoustic focusing to measure the surface charge on large particles, [2] but to our knowledge, our work is the first demonstration combining these two techniques in a continuous flow device. Marina et al. demonstrated superimposed dielectrophoresis (DEP) and acoustic focusing for enhanced separations [3], but these devices have limited throughput due to the rapid decay of DEP forces. Both acoustic standing waves and electric fields exert significant forces over the entire fluid volume in microchannels, thus allowing channels with larger dimensions (> 100 {micro}m) and high throughputs (10-100 {micro}L/min) necessary to process real-world volumes (1 mL). Previous work demonstrated acoustic focusing of microbeads [4] and biological species [5] in various geometries. We experimentally characterized our device by determining the biological size-cutoff where acoustic radiation pressure forces no longer transport biological particles. Figure 1 shows images of E

  2. NMR Constraints Analyser: a web-server for the graphical analysis of NMR experimental constraints.

    PubMed

    Heller, Davide Martin; Giorgetti, Alejandro

    2010-07-01

    Nuclear magnetic resonance (NMR) spectroscopy together with X-ray crystallography, are the main techniques used for the determination of high-resolution 3D structures of biological molecules. The output of an NMR experiment includes a set of lower and upper limits for the distances (constraints) between pairs of atoms. If the number of constraints is high enough, there will be a finite number of possible conformations (models) of the macromolecule satisfying the data. Thus, the more constraints are measured, the better defined these structures will be. The availability of a user-friendly tool able to help in the analysis and interpretation of the number of experimental constraints per residue, is thus of valuable importance when assessing the levels of structure definition of NMR solved biological macromolecules, in particular, when high-quality structures are needed in techniques such as, computational biology approaches, site-directed mutagenesis experiments and/or drug design. Here, we present a free publicly available web-server, i.e. NMR Constraints Analyser, which is aimed at providing an automatic graphical analysis of the NMR experimental constraints atom by atom. The NMR Constraints Analyser server is available from the web-page http://molsim.sci.univr.it/constraint. PMID:20513646

  3. Combination of spectroscopic methods: in situ NMR and UV/Vis measurements to understand the formation of group 4 metallacyclopentanes from the corresponding metallacyclopropenes.

    PubMed

    Beweries, Torsten; Fischer, Christian; Peitz, Stephan; Burlakov, Vladimir V; Arndt, Perdita; Baumann, Wolfgang; Spannenberg, Anke; Heller, Detlef; Rosenthal, Uwe

    2009-04-01

    By reaction of the dichloride rac-(ebthi)HfCl(2) [ebthi = 1,2-ethylene-1,1'-bis(eta(5)-tetrahydroindenyl)] with lithium in the presence of bis(trimethylsilyl)acetylene, the hafnacyclopropene rac-(ebthi)Hf(eta(2)-Me(3)SiC(2)SiMe(3)) (1-Hf) was obtained. The reaction of the blue-green complex 1-Hf with an excess of ethylene at room temperature leads by insertion of the olefin to the yellow-green hafnacyclopentene 2-Hf which is only stable in solution and eliminates the alkyne at 100 degrees C under ethylene to form the corresponding yellow hafnacyclopentane 3-Hf, which was characterized by X-ray crystal structure analysis. The reaction of 1-Hf to give stepwise via 2-Hf the complex 3-Hf was investigated in detail and compared to the formation and stability of the corresponding zirconacyclopropene 1-Zr, zirconacyclopentene 2-Zr, and zirconacyclopentane 3-Zr. Moreover, the reaction of the titanocene alkyne complex 1-Ti with ethylene was studied. For investigating the reaction behavior of the alkyne complexes 1-M, NMR spectroscopy was used and the results were compared with UV/vis spectroscopy, suggesting the existence of a bis-pi-complex prior to the formation of the hafnacyclopentene 2-Hf. PMID:19275148

  4. 224} studied by NMR

    SciTech Connect

    Furukawa, Y; Fang, X; Kögerler, P

    2014-05-14

    7Li nuclear magnetic resonance (NMR) studies have been performed to investigate magnetic properties and spin dynamics of Mn3+ (S = 2) spins in the giant polyoxometalate molecule {Mn40W224}. The 7Li-NMR line width is proportional to the external magnetic field H as expected in a paramagnetic state above 3 K. Below this temperature the line width shows a sudden increase and is almost independent of H, which indicates freezing of the local Mn3+ spins. The temperature dependence of T1 for both 1H and 7Li reveals slow spin dynamics at low temperatures, consistent with spin freezing. The slow spin dynamics is also evidenced by the observation of a peak of 1/T2 around 3 K, where the fluctuation frequency of spins is of the order of ~200 kHz. An explicit form of the temperature dependence of the fluctuation frequency of Mn3+ spins is derived from the nuclear relaxation data.

  5. The NMR phased array.

    PubMed

    Roemer, P B; Edelstein, W A; Hayes, C E; Souza, S P; Mueller, O M

    1990-11-01

    We describe methods for simultaneously acquiring and subsequently combining data from a multitude of closely positioned NMR receiving coils. The approach is conceptually similar to phased array radar and ultrasound and hence we call our techniques the "NMR phased array." The NMR phased array offers the signal-to-noise ratio (SNR) and resolution of a small surface coil over fields-of-view (FOV) normally associated with body imaging with no increase in imaging time. The NMR phased array can be applied to both imaging and spectroscopy for all pulse sequences. The problematic interactions among nearby surface coils is eliminated (a) by overlapping adjacent coils to give zero mutual inductance, hence zero interaction, and (b) by attaching low input impedance preamplifiers to all coils, thus eliminating interference among next nearest and more distant neighbors. We derive an algorithm for combining the data from the phased array elements to yield an image with optimum SNR. Other techniques which are easier to implement at the cost of lower SNR are explored. Phased array imaging is demonstrated with high resolution (512 x 512, 48-cm FOV, and 32-cm FOV) spin-echo images of the thoracic and lumbar spine. Data were acquired from four-element linear spine arrays, the first made of 12-cm square coils and the second made of 8-cm square coils. When compared with images from a single 15 x 30-cm rectangular coil and identical imaging parameters, the phased array yields a 2X and 3X higher SNR at the depth of the spine (approximately 7 cm). PMID:2266841

  6. NMR imaging of materials

    SciTech Connect

    Vinegar, H.J.; Rothwell, W.P.

    1988-03-01

    A method for obtaining at least one petrophysical property of a porous material containing therein at least one preselected fluid, is described, comprising: NMR imaging the material to generate signals dependent upon both M(0) and T/sub 1/ and M(0) and T/sub 2/, generating separate M(0), T/sub 1/ and T/sub 2/ images from the signals, and determining at least one petrophysical property from at least one of the images.

  7. NMR Studies of Peroxidases.

    NASA Astrophysics Data System (ADS)

    Veitch, Nigel Charles

    Available from UMI in association with The British Library. Requires signed TDF. Peroxidases are a haem-containing group of enzymes with a wide diversity of function within biological systems. While a common characteristic is the ability to catalyse the conversion of hydrogen peroxide to water, it is the accompanying processes of hormone synthesis and degradation which have generated such a high level of interest. However, information at the molecular level is limited to a single well-resolved crystal structure, that of yeast cytochrome c peroxidase. This thesis presents a strategy for the investigation of peroxidase structure and function based on proton nuclear magnetic resonance spectroscopy, a technique which has the ability to address aspects of both protein structure and protein dynamics in solution. The application of one- and two-dimensional NMR techniques has been developed in the context of plant peroxidases, notably the isoenzyme HRP-C derived from the horseradish root. Characterisation of the proton NMR spectra of HRP -C in resting and ligated states provided new information enabling the structure of the binding site for aromatic donor molecules, such as indole-3-propionic, ferulic and benzhydroxamic acids, to be resolved. In order to overcome difficulties encountered with a protein of the complexity of peroxidase, additional information was obtained from chemical shift parameters and the use of peroxidase variants produced by site-directed mutagenesis. A comparative study using NMR spectroscopy was undertaken for wild-type recombinant HRP-C expressed in Escherichia coli, and two protein variants with substitutions made to residues located on the distal side of the haem pocket, Phe41 to Val and Arg38 to Lys. NMR analyses of a plant peroxidase from barley grains and the fungal peroxidase from Coprinus cinereus were also successful using methods conceived with HRP-C. Examination of three specifically constructed recombinant protein variants of C. cinereus

  8. Absorption of Polyelectrolytes on Colloidal Surfaces as Studied by Electrophoretic and Dynamic Light-Scattering Techniques.

    PubMed

    Okubo; Suda

    1999-05-15

    zeta-Potential and the effective diameter of the colloidal spheres absorbed with the macro-cations and macro-anions are studied by the electrophoretic light-scattering and dynamic light-scattering measurements. Colloidal spheres used are monodispersed polystyrene (220 nm in diameter) and colloidal silica spheres (110 nm). Macro-ions used are sodium polyacrylate, sodium polymethylacrylate, sodium poly(styrene sulfonate), and poly-4-vinyl pyridines quaternized with ethyl bromide, n-butyl bromide, benzyl chloride, and 5% hexadecyl bromide and 95% benzyl chloride. Reversal of colloidal surface charges from negative to positive occurs abruptly above the critical concentration of macro-ions by the excess absorption of the macro-cations onto the anionic colloidal spheres, i.e., avalanche-type absorption. The effective diameter of colloidal spheres including the absorbed layers increases substantially by four- to tenfold. In the presence of large amount of macro-cations aggregation of colloidal spheres mediated by the layers of absorbed macro-cations may occur. Absorption also occurs on the anionic colloidal spheres in the presence of an excess amount of macro-anions by the dipole-dipole-type attractive interactions. Copyright 1999 Academic Press. PMID:10222098

  9. Electrophoretic deposition of bioactive glass coating on 316L stainless steel and electrochemical behavior study

    NASA Astrophysics Data System (ADS)

    Mehdipour, Mehrad; Afshar, Abdollah; Mohebali, Milad

    2012-10-01

    In this research, submicron bioactive glass (BG) particles were synthesized by a sol-gel process and were then coated on a 316L stainless steel substrate using an electrophoretic deposition (EPD) technique. Stable suspension of bioactive glass powders in ethanol solvent was prepared by addition of triethanol amine (TEA), which increased zeta potential from 16.5 ± 1.6 to 20.3 ± 1.4 (mv). Thickness, structure and electrochemical behavior of the coating were characterized. SEM studies showed that increasing EPD voltage leads to a coating with more agglomerated particles, augmented porosity and micro cracks. The results of Fourier transformed infrared (FTIR) spectroscopy revealed the adsorption of TEA via methyl and amid groups on bioactive glass particles. Presence of bioactive glass coating reduced corrosion current density (icorr) and shifted corrosion potential (Ecorr) toward more noble values in artificial saliva at room temperature. Percent porosity of the coating measured by potentiodynamic polarization technique increased as EPD voltage was raised. The results of impedance spectroscopic studies demonstrated that the coating acts as a barrier layer in artificial saliva.

  10. Contactless conductometric determination of methanol and ethanol in samples containing water after their electrophoretic desalination.

    PubMed

    Tůma, Petr; Opekar, František

    2015-08-01

    Determination of the contents of methanol and ethanol in aqueous solutions was performed by measuring the permittivity of solutions using a contactless conductivity detector (C(4) D) normally used for detection in capillary electrophoresis. The detection cell is a section of a fused silica capillary with an internal diameter of 50 μm with a pair of conductivity electrodes on the external walls. The C(4) D response to samples of methanol/water and ethanol/water mixtures is linear in the concentration interval of approx. 40-100% v/v alcohol content. In the analysis of technical samples of methanol and ethanol, the determination is disturbed by the presence of even trace amounts of salts. This interference can be effectively eliminated by integrated electrophoretic desalination of the sample by the application of a direct current electric voltage with a magnitude of 10 kV to the capillary with the injected sample zone. Under these conditions, the ions migrate out of the sample zone and the detector response is controlled purely by the permittivity of the solvent/water zone. Desalinating is effective for NaCl contents in the range from 0 to 5 mmol/L NaCl. The effectiveness of the desalinating process has been verified on MeOH/water samples and in determination of the ethanol content in distilled beverages normally available in the retail network. PMID:26031907

  11. Influence of surfactant structure on reverse micelle size and charge for nonpolar electrophoretic inks.

    PubMed

    Parent, Mary E; Yang, Jun; Jeon, Yoocharn; Toney, Michael F; Zhou, Zhang-Lin; Henze, Dick

    2011-10-01

    Electrophoretic inks, which are suspensions of colorant particles that are controllably concentrated and dispersed by applied electric fields, are the leading commercial technology for high-quality reflective displays. Extending the state of the art for high-fidelity color in these displays requires improved understanding and control of the colloidal systems. In these inks, reverse micelles in nonpolar media play key roles in media and particle charging. Here we investigate the effect of surfactant structure on reverse micelle size and charging properties by synthesizing different surfactants with variations in polyamine polar head groups. Small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS) were used to determine the micelle core plus shell size and micelle hydrodynamic radius, respectively. The results from SAXS agreed with DLS and showed that increasing polyamines in the surfactant head increased the micelle size. The hydrodynamic radius was also calculated on the basis of transient current measurements and agreed well with the DLS results. The transient current technique further determined that increasing polyamines increased the charge stabilization capability of the micelles and that an analogous commercial surfactant OLOA 11000 made for a lower concentration of charge-generating ions in solution. Formulating magenta inks with the various surfactants showed that the absence of amine in the surfactant head was detrimental to particle stabilization and device performance. PMID:21863832

  12. Highly photoluminescent nanocrystals based on a gold(I) complex and their electrophoretic patterning.

    PubMed

    Saitoh, Masashi; Balch, Alan L; Yuasa, Junpei; Tada, Kazuya; Onoda, Mitsuyoshi; Nakashima, Takuya; Kawai, Tsuyoshi

    2011-09-01

    The fabrication of nanocrystals (NCs) composed of the cationic Au(I) complex was demonstrated by the reprecipitation method in which the colloidal solution of the NCs showed brilliant green phosphorescence with a quantum yield of 83% in n-hexane. Characterization of the prepared NCs was performed by transmission electron microscopy observation and elemental analysis with energy-dispersive X-ray spectroscopy. The obtained Au(I) NCs were particles of random shapes with a diameter of 200-400 nm. The selected-area electron diffraction and X-ray diffraction measurements showed the characteristic diffraction patterns attributable to the crystal structure of the bulk crystal of the Au(I) complex. A similar method was performed with a different counteranion, leading to a colloidal solution of the microcrystals (MCs) with brilliant yellow phosphorescence and a quantum yield of 26% in n-hexane. Luminescence patterning of the NCs and MCs was also achieved successfully by electrophoretic deposition onto an indium tin oxide (ITO)-coated glass substrate, resulting in characteristic luminescence patterns on the ITO substrates with relatively high photoluminescence quantum yields. PMID:21711039

  13. Determination of electrophoretic mobilities and hydrodynamic radii of three humic substances as a function of pH and ionic strength.

    PubMed

    Hosse, M; Wilkinson, K J

    2001-11-01

    Capillary electrophoresis (CE) and fluorescence correlation spectroscopy (FCS) were employed to determine electrophoretic mobilities and hydrodynamic sizes of three humic substances (IHSS aquatic fulvic acid (FA), IHSS aquatic humic acid (HA), and IHSS peat humic acid (PHA)) as a function of pH and ionic strength. A slight aggregation corresponding to the formation of dimers and trimers was observed at low pH using fluorescence correlation spectroscopy (FCS). For example, for the peat humic acid, diffusion coefficients decreased from 2.1 x 10(-10) m2 s(-1) at pH 4 to 2.4 x 10(-10) m2 s(-1) at pH 11. For all three humic substances, electrophoretic mobilities were also shown to decrease significantly below pH 6. Calculated zeta potentials observed at high pH of -69 mV (FA), -62 mV (HA), and -63 mV (PHA) decreased to -39, -50, and -47 mV, respectively, under slightly acidic pH (4.5-4.8) conditions. No evidence of ionic strength induced aggregation was found using fluorescence correlation spectroscopy (FCS); diffusion coefficients increased slightly (<25%) with increasing ionic strength (up to 1 M). Negative electrophoretic mobilities decreased to a maximum measured ionic strength of 0.18 M. Above this ionic strength, no peaks were observed due to an increased HS adsorption to the capillary wall and an important decrease in electroosmotic flow. Interpretation of electrophoretic mobilities determined by CE is complicated by the fact that under certain conditions, HS appeared to be complexed by CE buffer systems, including MES, BES, and AMPSO. PMID:11718346

  14. Controlled method of reducing electrophoretic mobility of macromolecules, particles, or cells

    NASA Technical Reports Server (NTRS)

    Vanalstine, James M. (Inventor)

    1992-01-01

    A method of reducing electrophoretic mobility of macromolecules, particles, cells, and other substances is provided which comprises interacting in a conventional electrophoretic separating procedure, the substances with a polymer-linked affinity compound comprised of a hydrophilic neutral polymer such as polyethylene glycol bound to a second component such as a hydrophobic compound, an immunocompound such as an antibody or antibody active fragment, or a ligand such as a hormone, drug, antigen, or a hapten. The reduction of electrophoretic mobility achieved is directly proportional to the concentration of the polymer-linked affinity compound employed, and such reduction can comprise up to 100 percent for particular particles and cells. The present invention is advantageous in that electrophoretic separation can now be achieved for substances whose native surface charge structure had prevented them from being separated by normal electrophoretic means. Depending on the affinity component utilized, separation can be achieved on the basis of the specific/irreversible, specific/reversible, semi-specific/reversible, relatively nonspecific/reversible, or relatively nonspecific/irreversible ligand-substance interactions.

  15. Fabrication and kinetics study of nano-Al/NiO thermite film by electrophoretic deposition.

    PubMed

    Zhang, Daixiong; Li, Xueming

    2015-05-21

    Nano-Al/NiO thermites were successfully prepared as film by electrophoretic deposition (EPD). For the key issue of this EPD, a mixture solvent of ethanol-acetylacetone (1:1 in volume) containing 0.00025 M nitric acid was proved to be a suitable dispersion system for EPD. The kinetics of electrophoretic deposition for both nano-Al and nano-NiO were investigated; the linear relation between deposition weight and deposition time in short time and parabolic relation in prolonged time were observed in both EPDs. The critical transition time between linear deposition kinetics and parabolic deposition kinetics for nano-Al and nano-NiO were 20 and 10 min, respectively. The theoretical calculation of the kinetics of electrophoretic deposition revealed that the equivalence ratio of nano-Al/NiO thermites film would be affected by the behavior of electrophoretic deposition for nano-Al and nano-NiO. The equivalence ratio remained steady when the linear deposition kinetics dominated for both nano-Al and nano-NiO. The equivalence ratio would change with deposition time when deposition kinetics for nano-NiO changed into parabolic kinetics dominated after 10 min. Therefore, the rule was suggested to be suitable for other EPD of bicomposites. We also studied thermodynamic properties of electrophoretic nano-Al/NiO thermites film as well as combustion performance. PMID:25950271

  16. Study of the Electrophoretic Behavior of Cephalosporins by Capillary Zone Electrophoresis

    PubMed Central

    Hancu, Gabriel; Sasebeşi, Adina; Rusu, Aura; Kelemen, Hajnal; Ciurba, Adriana

    2015-01-01

    Purpose: The aim of the study was the characterization of the electrophoretic behavior of cephalosporins from different generation having different structural characteristics in order to develop a rapid, simple and efficient capillary electrophoretic method for their identification and simultaneous separation from complex mixtures. Methods: Ten cephalosporin derivatives (cefaclor, cefadroxil, cefalexin, cefazolin, cefoxitin, cefuroxime, cefoperazone, cefotaxime, ceftazidime, ceftriaxone) were analyzed by capillary zone electrophoresis using different background electrolyte solutions at different pH values. Electrophoretic mobilities of the analytes were calculated, the influence of the electrophoretic parameteres on the separation was established and the analytical conditions were optimized. Results: Taking into consideration their structural and chemical properties cephalosporins can be detected over a pH range between 6 and 10. The best results were obtained using a buffer solution containing 25 mM disodium hydrogenophosphate - 25 mM sodium dihydrogenophosphate, at a pH – 7.00, + 25 kV voltage at a temperature of 25 °C, UV detection at 210 nm. Using the optimized analytical conditions we achieved the simultaneous baseline separation for seven cephalosporins in less then 10 minutes. Conclusion: Using the described optimized electrophoretic procedures, capillary electrophoresis can be used for the identification and determination of cephalosporins in formulated pharmaceutical products and for their separation from complex mixtures. PMID:26236661

  17. Electrophoretic mobility patterns of immunologically phenotyped cells in different hemopoietic malignancies.

    PubMed

    Babusíková, O; Koníková, E; Ujházy, P

    1986-01-01

    The electrophoretic mobility distribution along with the immunologic phenotype (rosette tests, surface membrane immunoglobulin determination and mainly the detection of differentiation and leukemia-associated antigens by monoclonal antibodies) have been studied in 120 patients with different hemopoietic cell malignancies and in a group of healthy donors. The aim of our study was to compare the electrophoretic mobility character of malignant cells with that of normal T and B lymphocytes and their immune phenotype. Normal peripheral blood lymphocytes showed the typical bimodal pattern of two clearly distinguishable populations of different electrophoretic mobilities, corresponding to T and B cells. In leukemia and lymphoma cells the sharp unimodal peak has appeared, which was attributed to monoclonal origin of these cells. Moreover, the electrophoretic mobility of cells in different hemopoietic cell malignancies reflected different cell lineages and maturation stages within the given lineage group. Utilizing of the cell electrophoretic mobility as an additional marker to the immunologic data for the characterization of leukemia and lymphoma cells is proposed. PMID:3808126

  18. Bayesian reconstruction of projection reconstruction NMR (PR-NMR).

    PubMed

    Yoon, Ji Won

    2014-11-01

    Projection reconstruction nuclear magnetic resonance (PR-NMR) is a technique for generating multidimensional NMR spectra. A small number of projections from lower-dimensional NMR spectra are used to reconstruct the multidimensional NMR spectra. In our previous work, it was shown that multidimensional NMR spectra are efficiently reconstructed using peak-by-peak based reversible jump Markov chain Monte Carlo (RJMCMC) algorithm. We propose an extended and generalized RJMCMC algorithm replacing a simple linear model with a linear mixed model to reconstruct close NMR spectra into true spectra. This statistical method generates samples in a Bayesian scheme. Our proposed algorithm is tested on a set of six projections derived from the three-dimensional 700 MHz HNCO spectrum of a protein HasA. PMID:25218584

  19. Facing and Overcoming Sensitivity Challenges in Biomolecular NMR Spectroscopy.

    PubMed

    Ardenkjaer-Larsen, Jan-Henrik; Boebinger, Gregory S; Comment, Arnaud; Duckett, Simon; Edison, Arthur S; Engelke, Frank; Griesinger, Christian; Griffin, Robert G; Hilty, Christian; Maeda, Hidaeki; Parigi, Giacomo; Prisner, Thomas; Ravera, Enrico; van Bentum, Jan; Vega, Shimon; Webb, Andrew; Luchinat, Claudio; Schwalbe, Harald; Frydman, Lucio

    2015-08-01

    In the Spring of 2013, NMR spectroscopists convened at the Weizmann Institute in Israel to brainstorm on approaches to improve the sensitivity of NMR experiments, particularly when applied in biomolecular settings. This multi-author interdisciplinary Review presents a state-of-the-art description of the primary approaches that were considered. Topics discussed included the future of ultrahigh-field NMR systems, emerging NMR detection technologies, new approaches to nuclear hyperpolarization, and progress in sample preparation. All of these are orthogonal efforts, whose gains could multiply and thereby enhance the sensitivity of solid- and liquid-state experiments. While substantial advances have been made in all these areas, numerous challenges remain in the quest of endowing NMR spectroscopy with the sensitivity that has characterized forms of spectroscopies based on electrical or optical measurements. These challenges, and the ways by which scientists and engineers are striving to solve them, are also addressed. PMID:26136394

  20. Membrane Protein Structure and Dynamics from NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hong, Mei; Zhang, Yuan; Hu, Fanghao

    2012-05-01

    We review the current state of membrane protein structure determination using solid-state nuclear magnetic resonance (NMR) spectroscopy. Multidimensional magic-angle-spinning correlation NMR combined with oriented-sample experiments has made it possible to measure a full panel of structural constraints of membrane proteins directly in lipid bilayers. These constraints include torsion angles, interatomic distances, oligomeric structure, protein dynamics, ligand structure and dynamics, and protein orientation and depth of insertion in the lipid bilayer. Using solid-state NMR, researchers have studied potassium channels, proton channels, Ca2+ pumps, G protein-coupled receptors, bacterial outer membrane proteins, and viral fusion proteins to elucidate their mechanisms of action. Many of these membrane proteins have also been investigated in detergent micelles using solution NMR. Comparison of the solid-state and solution NMR structures provides important insights into the effects of the solubilizing environment on membrane protein structure and dynamics.

  1. Quantitative structure parameters from the NMR spectroscopy of quadrupolar nuclei

    DOE PAGESBeta

    Perras, Frédéric A.

    2016-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is one of the most important characterization tools in chemistry, however, 3/4 of the NMR active nuclei are underutilized due to their quadrupolar nature. This short review centers on the development of methods that use solid-state NMR of quadrupolar nuclei for obtaining quantitative structural information. Namely, techniques using dipolar recoupling as well as the resolution afforded by double-rotation are presented for the measurement of spin–spin coupling between quadrupoles, enabling the measurement of internuclear distances and connectivities. Two-dimensional

  2. Quantitative structure parameters from the NMR spectroscopy of quadrupolar nuclei

    SciTech Connect

    Perras, Frederic A.

    2015-12-15

    Here, nuclear magnetic resonance (NMR) spectroscopy is one of the most important characterization tools in chemistry, however, 3/4 of the NMR active nuclei are underutilized due to their quadrupolar nature. This short review centers on the development of methods that use solid-state NMR of quadrupolar nuclei for obtaining quantitative structural information. Namely, techniques using dipolar recoupling as well as the resolution afforded by double-rotation are presented for the measurement of spin–spin coupling between quadrupoles, enabling the measurement of internuclear distances and connectivities.

  3. Solid-state NMR for bacterial biofilms

    NASA Astrophysics Data System (ADS)

    Reichhardt, Courtney; Cegelski, Lynette

    2014-04-01

    Bacteria associate with surfaces and one another by elaborating an extracellular matrix to encapsulate cells, creating communities termed biofilms. Biofilms are beneficial in some ecological niches, but also contribute to the pathogenesis of serious and chronic infectious diseases. New approaches and quantitative measurements are needed to define the composition and architecture of bacterial biofilms to help drive the development of strategies to interfere with biofilm assembly. Solid-state nuclear magnetic resonance (NMR) is uniquely suited to the examination of insoluble and complex macromolecular and whole-cell systems. This article highlights three examples that implement solid-state NMR to deliver insights into bacterial biofilm composition and changes in cell-wall composition as cells transition to the biofilm lifestyle. Most recently, solid-state NMR measurements provided a total accounting of the protein and polysaccharide components in the extracellular matrix of an Escherichia coli biofilm and transformed our qualitative descriptions of matrix composition into chemical parameters that permit quantitative comparisons among samples. We present additional data for whole biofilm samples (cells plus the extracellular matrix) that complement matrix-only analyses. The study of bacterial biofilms by solid-state NMR is an exciting avenue ripe with many opportunities and we close the article by articulating some outstanding questions and future directions in this area.

  4. New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella thermoacetica metabolic profiles.

    PubMed

    Xue, Junfeng; Isern, Nancy G; Ewing, R James; Liyu, Andrei V; Sears, Jesse A; Knapp, Harlan; Iversen, Jens; Sisk, Daniel R; Ahring, Birgitte K; Majors, Paul D

    2014-10-01

    An in situ nuclear magnetic resonance (NMR) bioreactor was developed and employed to monitor microbial metabolism under batch growth conditions in real time. We selected Moorella thermoacetica ATCC 49707 as a test case. M. thermoacetica (formerly Clostridium thermoaceticum) is a strictly anaerobic, thermophilic, acetogenic, gram-positive bacterium with potential for industrial production of chemicals. The metabolic profiles of M. thermoacetica were characterized during growth in batch mode on xylose (a component of lignocellulosic biomass) using the new generation NMR bioreactor in combination with high-resolution NMR (HR-NMR) spectroscopy. In situ NMR measurements were performed using water-suppressed H-1 NMR spectroscopy at 500 MHz, and aliquots of the bioreactor contents were taken for 600-MHz HR-NMR spectroscopy at specific intervals to confirm metabolite identifications and expand metabolite coverage. M. thermoacetica demonstrated the metabolic potential to produce formate, ethanol, and methanol from xylose, in addition to its known capability of producing acetic acid. Real-time monitoring of bioreactor conditions showed a temporary pH decrease, with a concomitant increase in formic acid during exponential growth. Fermentation experiments performed outside of the magnet showed that the strong magnetic field employed for NMR detection did not significantly affect cell metabolism. Use of the in situ NMR bioreactor facilitated monitoring of the fermentation process, enabling identification of intermediate and endpoint metabolites and their correlation with pH and biomass produced during culture growth. Real-time monitoring of culture metabolism using the NMR bioreactor in combination with HR-NMR spectroscopy will allow optimization of the metabolism of microorganisms producing valuable bioproducts. PMID:24946863

  5. Improved nuclear magnetic resonance apparatus having semitoroidal rf coil for use in topical NMR and NMR imaging

    DOEpatents

    Fukushima, E.; Roeder, S.B.W.; Assink, R.A.; Gibson, A.A.V.

    1984-01-01

    An improved nuclear magnetic resonance (NMR) apparatus for use in topical magnetic resonance (TMR) spectroscopy and other remote sensing NMR applications includes a semitoroidal radio frequency (rf) coil. The semitoroidal rf coil produces an effective alternating magnetic field at a distance from the poles of the coil, so as to enable NMR measurements to be taken from selected regions inside an object, particularly including human and other living subjects. The semitoroidal rf coil is relatively insensitive to magnetic interference from metallic objects located behind the coil, thereby rendering the coil particularly suited for use in both conventional and superconducting NMR magnets. The semitoroidal NMR coil can be constructed so that it emits little or no excess rf electric field associated with the rf magnetic field, thus avoiding adverse effects due to dielectric heating of the sample or to any other interaction of the electric field with the sample.

  6. Background suppression in MAS NMR

    NASA Astrophysics Data System (ADS)

    White, Jeffery L.; Beck, Larry W.; Ferguson, David B.; Haw, James F.

    Pulse sequences for suppressing background signals from spinning modules used in magic-angle spinning NMR are described. These pulse sequences are based on spatially selective composite 90° pulses originally reported by Bax, which provide for no net excitation of spins outside the homogeneous region of the coil. We have achieved essentially complete suppression of background signals originating from our Vespel spinning module (which uses a free-standing coil) in both 1H and 13C spectra without notable loss in signal intensity. Successful modification of both Bloch decay and cross-polarization pulse sequences to include spatially selective pulses was essential to acquire background-free spectra for weak samples. Background suppression was also found to be particularly valuable for both T1 and T1 ϱ, relaxation measurements.

  7. Identification and quantitation of morphological cell types in electrophoretically separated human embryonic kidney cell cultures

    NASA Technical Reports Server (NTRS)

    Williams, K. B.; Kunze, M. E.; Todd, P. W.

    1985-01-01

    Four major cell types were identified by phase microscopy in early passage human embryonic kidney cell cultures. They are small and large epithelioid, domed, and fenestrated cells. Fibroblasts are also present in some explants. The percent of each cell type changes with passage number as any given culture grows. As a general rule, the fraction of small epithelioid cells increases, while the fraction of fenestrated cells, always small, decreases further. When fibroblasts are present, they always increase in percentage of the total cell population. Electrophoretic separation of early passage cells showed that the domed cells have the highest electrophoretic mobility, fibroblasts have an intermediate high mobility, small epithelioid cells have a low mobility, broadly distributed, and fenestrated cells have the lowest mobility. All cell types were broadly distributed among electrophoretic subfractions, which were never pure but only enriched with respect to a given cell type.

  8. Electrical characterization of electrophoretically coated aluminum samples for photovoltaic concentrator application

    SciTech Connect

    Sugimura, R.S.; Mon, G.R.; Ross, R.G. Jr.

    1992-10-01

    The practicality of using a thin-film styrene/acrylate copolymer electrophoretic coating to isolate concentrator cells electrically from their surroundings in a photovoltaic concentrator module is assessed. Only the electrical isolation problem was investigated. The approach was to subject various types of EP-coated aluminum specimens to electrical stress testing and to aging tests while monitoring coating electrical resistivity properties. It was determined that, in general, longer processing times--i.e., thicker electrophoretic layers--resulted in better voltage-withstand properties. In particular, a two-minute processing time seemed sufficient to provide the electrical isolation required in photovoltaic concentrator application applications. Even though electrophoretic coatings did not seem to fill voids in porous-anodized aluminum substrates, breakdown voltages generally exceeded hi-pot pass-fail voltage levels with a comfortable margin. 6 refs, 11 figs, 5 tabs.

  9. Electrophoretic separation techniques and their hyphenation to mass spectrometry in biological inorganic chemistry.

    PubMed

    Holtkamp, Hannah; Grabmann, Gerlinde; Hartinger, Christian G

    2016-04-01

    Electrophoretic methods have been widely applied in research on the roles of metal complexes in biological systems. In particular, CE, often hyphenated to a sensitive MS detector, has provided valuable information on the modes of action of metal-based pharmaceuticals, and more recently new methods have been added to the electrophoretic toolbox. The range of applications continues to expand as a result of enhanced CE-to-MS interfacing, with sensitivity often at picomolar level, and evolved separation modes allowing for innovative sample analysis. This article is a followup to previous reviews about CE methods in metallodrug research (Electrophoresis, 2003, 24, 2023-2037; Electrophoresis, 2007, 28, 3436-3446; Electrophoresis, 2012, 33, 622-634), also providing a comprehensive overview of metal species studied by electrophoretic methods hyphenated to MS. It highlights the latest CE developments, takes a sneak peek into gel electrophoresis, traces biomolecule labeling, and focuses on the importance of early-stage drug development. PMID:26643265

  10. Capillary electrophoresis separation of vinpocetine and related compounds: prediction of electrophoretic mobilities in partly aqueous media.

    PubMed

    Mazák, K; Szakács, Z; Nemes, A; Noszál, B

    2000-07-01

    Offord's equation, a relationship between electrophoretic mobility and charge, size and shape of peptides, has been extended to quantitate the electrophoretic mobility of vinca alkaloids. Partly aqueous protonation constants and the derived theoretical mobilities have been proven to be able to predict experimental electrophoretic mobilities. In practice, seven vincamine derivatives of very low water-solubility were separated by capillary electrophoresis. Buffer total concentration, apparent pH and methanol content, the three most important parameters of the running buffer, were used in triangular resolution mapping to characterize separation. Even though electrophoresis is well known to slow down in partly aqueous media, under our optimized circumstances a baseline separation was achieved within 8 min in each case. PMID:10939454

  11. Nonlinear electrophoretic response yields a unique parameter for separation of biomolecules

    PubMed Central

    Pel, Joel; Broemeling, David; Mai, Laura; Poon, Hau-Ling; Tropini, Giorgia; Warren, René L.; Holt, Robert A.; Marziali, Andre

    2009-01-01

    We demonstrate a unique parameter for biomolecule separation that results from the nonlinear response of long, charged polymers to electrophoretic fields and apply it to extraction and concentration of nucleic acids from samples that perform poorly under conventional methods. Our method is based on superposition of synchronous, time-varying electrophoretic fields, which can generate net drift of charged molecules even when the time-averaged molecule displacement generated by each field individually is zero. Such drift can only occur for molecules, such as DNA, whose motive response to electrophoretic fields is nonlinear. Consequently, we are able to concentrate DNA while rejecting high concentrations of contaminants. We demonstrate one application of this method by extracting DNA from challenging samples originating in the Athabasca oil sands. PMID:19706437

  12. Accurate measurements of {sup 13}C-{sup 13}C distances in uniformly {sup 13}C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy

    SciTech Connect

    Straasø, Lasse Arnt; Nielsen, Jakob Toudahl; Bjerring, Morten; Nielsen, Niels Chr.; Khaneja, Navin

    2014-09-21

    Application of sets of {sup 13}C-{sup 13}C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important {sup 13}C-{sup 13}C distances in uniformly {sup 13}C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl ({sup 13}C′) and aliphatic ({sup 13}C{sub aliphatic}) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly {sup 13}C,{sup 15}N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of {sup 13}C′-{sup 13}C{sub aliphatic} distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform {sup 13}C,{sup 15}N-labeling on the FGAIL fragment.

  13. NMR Methods, Applications and Trends for Groundwater Evaluation and Management

    NASA Astrophysics Data System (ADS)

    Walsh, D. O.; Grunewald, E. D.

    2011-12-01

    Nuclear magnetic resonance (NMR) measurements have a tremendous potential for improving groundwater characterization, as they provide direct detection and measurement of groundwater and unique information about pore-scale properties. NMR measurements, commonly used in chemistry and medicine, are utilized in geophysical investigations through non-invasive surface NMR (SNMR) or downhole NMR logging measurements. Our recent and ongoing research has focused on improving the performance and interpretation of NMR field measurements for groundwater characterization. Engineering advancements have addressed several key technical challenges associated with SNMR measurements. Susceptibility of SNMR measurements to environmental noise has been dramatically reduced through the development of multi-channel acquisition hardware and noise-cancellation software. Multi-channel instrumentation (up to 12 channels) has also enabled more efficient 2D and 3D imaging. Previous limitations in measuring NMR signals from water in silt, clay and magnetic geology have been addressed by shortening the instrument dead-time from 40 ms to 4 ms, and increasing the power output. Improved pulse sequences have been developed to more accurately estimate NMR relaxation times and their distributions, which are sensitive to pore size distributions. Cumulatively, these advancements have vastly expanded the range of environments in which SNMR measurements can be obtained, enabling detection of groundwater in smaller pores, in magnetic geology, in the unsaturated zone, and nearby to infrastructure (presented here in case studies). NMR logging can provide high-resolution estimates of bound and mobile water content and pore size distributions. While NMR logging has been utilized in oil and gas applications for decades, its use in groundwater investigations has been limited by the large size and high cost of oilfield NMR logging tools and services. Recently, engineering efforts funded by the US Department of

  14. Summary of Miniature NMR Development

    SciTech Connect

    Friedman, Gennady; Feinerman, Alan

    2000-12-31

    The effort in this project has been in 3 distinct directions: (1) First, they focused on development of miniature microfabricated micro-coil NMR detectors with maximum Signal-to-Noise (SNR) ratio. (2) Secondly, they focused on design of miniature micro-coil NMR detectors that have minimal effect on the NMR spectrum distortions. (3) Lastly they focused on the development of a permanent magnet capable of generating fields on the order of 1 Tesla with better than 10 ppm uniformity.

  15. Properties of electrophoretic fractions of human embryonic kidney cells separated on space shuttle flight STS-8

    NASA Technical Reports Server (NTRS)

    Morrison, D. R.; Lewis, M. L.; Barlow, G. H.; Todd, P. W.; Kunze, M. E.; Sarnoff, B. E.; Li, Z. K.

    1985-01-01

    Suspensions of cultured primary human embryonic kidney cells were subjected to continuous flow electrophoresis on Space Shuttle flight STS-8. The objectives of the experiments were to obtain electrophoretically separated fractions of the original cell populations and to test these fractions for the amount and kind of urokinase (a kidney plasminogen activator that is used medically for digesting blood clots), the morphologies of cells in the individual fractions, and their cellular electrophoretic mobilities after separation and subsequent proliferation. Individual fractions were successfully cultured after return from orbit, and they were found to differ substantially from one another and from the starting sample with respect to all of these properties.

  16. Electrophoretic deposition of hyaluronic acid and composite films for biomedical applications

    NASA Astrophysics Data System (ADS)

    Ma, R.; Li, Y.; Zhitomirsky, I.

    2010-06-01

    Hyaluronic acid (HYH) is a natural biopolymer, which has tremendous potential for various biomedical applications. Electrophoretic deposition (EPD) methods have been developed for the fabrication of HYH films and composites. New methods for the immobilization of drugs and proteins have been utilized for the fabrication of organic composites. Electrophoretic deposition enabled the fabrication of organic-inorganic composites containing bioceramics and bioglass in the HYH matrix. It was shown that the deposition yield, microstructure, and composition of the films can be controlled. Potential applications of EPD for the surface modification of biomedical implants and fabrication of biosensors are highlighted.

  17. Properties of electrophoretic fractions of human embryonic kidney cells separated on space shuttle flight STS-8

    NASA Astrophysics Data System (ADS)

    Morrison, Dennis R.; Lewis, Marian L.; Barlow, Grant H.; Todd, Paul; Kunze, M. Elaine; Sarnoff, Burton E.; Li, Zhankui

    Suspensions of cultured primary human embryonic kidney cells were subjected to continuous flow electrophoresis on Space Shuttle flight STS-8. The objectives of the experiments were to obtain electrophoretically separated fractions of the original cell populations and to test these fractions for the amount and kind of urokinase (a kidney plasminogen activator that is used medically for digesting blood clots), the morphologies of cells in the individual fractions, and their cellular electrophoretic mobilities after separation and subsequent proliferation. Individual fractions were successfully cultured after return from orbit, and they were found to differ substantially from one another and from the starting sample with respect to all of these properties.

  18. Polyacrylamide gel electrophoretic methods in the separation of structural muscle proteins.

    SciTech Connect

    Barany, K.; Barany, M.; Giometti, C. S.; Center for Mechanistic Biology and Biotechnology; Univ. of Illinois at Chicago

    1995-04-28

    Polyacrylamide gel electrophoresis plays a major role in analyzing the function of muscle structural proteins. This review describes one- and two-dimensional gel electrophoretic methods for qualitative and quantitative investigation of the muscle proteins, with special emphasis on determination of protein phosphorylation. The electrophoretic studies established the subunit structures of the muscle proteins, characterized their multiple forms, revealed changes in subunit composition or shifts in isoform distribution of specific proteins during development, upon stimulation or denervation of the muscle. Protein phosphorylation during muscle contraction is preferentially studied by two-dimensional gel electrophoresis. The same method demonstrated protein alterations in human neuromuscular diseases.

  19. NMR T{sub 1} relaxation time measurements and calculations with translational and rotational components for liquid electrolytes containing LiBF{sub 4} and propylene carbonate

    SciTech Connect

    Richardson, P. M. Voice, A. M. Ward, I. M.

    2013-12-07

    Longitudinal relaxation (T{sub 1}) measurements of {sup 19}F, {sup 7}Li, and {sup 1}H in propylene carbonate/LiBF{sub 4} liquid electrolytes are reported. Comparison of T{sub 1} values with those for the transverse relaxation time (T{sub 2}) confirm that the measurements are in the high temperature (low correlation time) limit of the T{sub 1} minimum. Using data from pulsed field gradient measurements of self-diffusion coefficients and measurements of solution viscosity measured elsewhere, it is concluded that although in general there are contributions to T{sub 1} from both translational and rotational motions. For the lithium ions, this is mainly translational, and for the fluorine ions mainly rotational.

  20. NMR analysis of a fluorocarbon copolymer

    SciTech Connect

    Smith, R.E.; Smith, C.H.

    1987-10-01

    Vinylidene fluoride (VF/sub 2/) can be copolymerized with chlorotrifluoroethylene (CTFE) in an aqueous emulsion using a peroxide chain initiator. The physical properties of the resulting fluorocarbon polymer depend on the ratio of VF/sub 2/ to CTFE and the randomness of the copolymerization. When CTFE and VF are polymerized in an approximately 3:1 mole ratio, the resulting polymer is soluble in acetone (and other solvents) at room temperature. Using proton and fluorine-19 NMR, the mole ratio of CTFE to VF/sub 2/, the emulsifier (perfluorodecanoate) concentration, and the randomness of copolymerization can be determined. A trifluorotoluene internal standard is added to a d/sub 6/-acetone solution of the fluoropolymer. Proton NMR is used to determine the amount of VF/sub 2/. Fluorine-19 NMR is used to measure the amount of emulsifier and the randomness of copolymerization. Each analysis requires about 5 minutes, and is quite precise, with relative standard deviations from 3 to 10% (10 replicates analyzed). In addition, the results from NMR analyses agree well with wet chemical analyses. 4 refs., 3 figs., 3 tabs.

  1. Electrophoretic Deposition of α-Fe2O3/Chitosan Nanocomposite Coatings for Functional and Biomedical Applications.

    PubMed

    Cabanas-Polo, S; Distaso, M; Peukert, W; Boccaccini, A R

    2015-12-01

    Promising composite coatings based on hematite (α-Fe2O3) mesocrystals of size 110 nm and chitosan (CHT) molecules for different biotechnological applications have been successfully obtained by electrophoretic deposition (EPD). Homogeneous and reproducible coatings have been obtained by studying and controlling the chemical interactions between both phases (α-Fe2O3 and CHT). A voltage of 25 V and a deposition time of 5 min were chosen as best deposition conditions, which resulted in highly homogeneous coatings with well-distributed α-Fe2O3 particles. According to TGA measurements, the content of α-Fe2O3 and chitosan in the final composite coating were found to be 74 and 26 wt%, respectively. The presence of both phases in the composite coating was determined by XRD analysis and the coatings microstructure was observed by SEM. PMID:26682461

  2. Nanoscale NMR and NQR with Nitrogen Vacancy Centers

    NASA Astrophysics Data System (ADS)

    Urbach, Elana; Lovchinsky, Igor; Sanchez-Yamagishi, Javier; Choi, Soonwon; Bylinskii, Alexei; Dwyer, Bo; Andersen, Trond; Sushkov, Alex; Park, Hongkun; Lukin, Mikhail

    2016-05-01

    Nuclear quadrupole resonance (NQR) is a powerful tool which is used to detect quadrupolar interaction in nuclear spins with I > 1/2. Conventional NQR and NMR technology, however, rely on measuring magnetic fields from a macroscopic number of spins. Extending NMR and NQR techniques to the nanoscale could allow us to learn structural information about interesting materials and biomolecules. We present recent progress on using Nitrogen-Vacancy (NV) centers in diamond to perform room temperature nanoscale NMR and NQR spectroscopy on small numbers of nuclear spins in hexagonal boron nitride.

  3. Jointly deriving NMR surface relaxivity and pore size distributions by NMR relaxation experiments on partially desaturated rocks

    NASA Astrophysics Data System (ADS)

    Mohnke, O.; Hughes, B.

    2014-06-01

    Nuclear magnetic resonance (NMR) relaxometry is a geophysical method widely used in borehole and laboratory applications to nondestructively infer transport and storage properties of rocks and soils as it is directly sensitive to the water/oil content and pore sizes. However, for inferring pore sizes, NMR relaxometry data need to be calibrated with respect to a surface interaction parameter, surface relaxivity, which depends on the type and mineral constituents of the investigated rock. This study introduces an inexpensive and quick alternative to the classical calibration methods, e.g., mercury injection, pulsed field gradient (PFG) NMR, or grain size analysis, which allows for jointly estimating NMR surface relaxivity and pore size distributions using NMR relaxometry data from partially desaturated rocks. Hereby, NMR relaxation experiments are performed on the fully saturated sample and on a sample partially drained at a known differential pressure. Based on these data, the (capillary) pore radius distribution and surface relaxivity are derived by joint optimization of the Brownstein-Tarr and the Young-Laplace equation assuming parallel capillaries. Moreover, the resulting pore size distributions can be used to predict water retention curves. This inverse modeling approach—tested and validated using NMR relaxometry data measured on synthetic porous borosilicate samples with known petrophysical properties (i.e., permeability, porosity, inner surfaces, pore size distributions)—yields consistent and reproducible estimates of surface relaxivity and pore radii distributions. Also, subsequently calculated water retention curves generally correlate well with measured water retention curves.

  4. Multifunctional pulse sequence generator for pulse NMR

    NASA Astrophysics Data System (ADS)

    Wang, Dongsheng

    1988-06-01

    A new multifunctional pulse sequence generator has been designed and constructed. It can conveniently generate various pulse sequences used in nuclear-magnetic resonance (NMR) to measure the spin-lattice relaxation time T1, the spin-spin relaxation time T2, and the spin-locking relaxation time T1 ρ. It can also be used in pulse Fourier transform NMR and double resonance. The intervals of pulses can increase automatically with sequence repetitions and the generator can be used in two-dimensional spectrum measurement and spin-density imaging research. The sequences can be generated through four different triggering methods and there are two synchronous pulse outputs and fifteen auxiliary pulse outputs, so the generator can be conveniently interfaced with a computer or other instruments. The circuitry, functions, and features of the generator are described in this article.

  5. Two-dimensional NMR spectroscopy

    SciTech Connect

    Croasmun, W.R.; Carlson, R.M.K.

    1987-01-01

    Written for chemists and biochemists who are not NMR spectroscopists, but who wish to use the new techniques of two-dimensional NMR spectroscopy, this book brings together for the first time much of the practical and experimental data needed. It also serves as information source for industrial, academic, and graduate student researchers who already use NMR spectroscopy, but not yet in two dimensions. The authors describe the use of 2-D NMR in a wide variety of chemical and biochemical fields, among them peptides, steroids, oligo- and poly-saccharides, nucleic acids, natural products (including terpenoids, alkaloids, and coal-derived heterocyclics), and organic synthetic intermediates. They consider throughout the book both the advantages and limitations of using 2-D NMR.

  6. Electrophoretic isoenzyme patterns of the pathogenic and non-pathogenic intestinal amoebae of man.

    PubMed

    Sargeaunt, P G; Williams, J E

    1979-01-01

    Cultured stocks of Entamoeba hartmanni, Endolimax nana, Iodamoeba buetschlli and Dientamoeba fragilis were compared with the four Entamoeba histolytical groups already described (SARGEAUNT et al., 1978), by the electrophoretic patterns of three enzymes: glucose phosphate isomerase (GPI), phosphoglucomutase (PGM) and L-malate: NADP+ oxidoreductase (oxalacetate-decarboxylating) (ME). All the species were easily distinguished by their characteristic patterns. PMID:473310

  7. Electrophoretic Deposition for Cholesteric Liquid-Crystalline Devices with Memory and Modulation of Reflection Colors.

    PubMed

    Tokunaga, Shoichi; Itoh, Yoshimitsu; Yaguchi, Yuya; Tanaka, Hiroyuki; Araoka, Fumito; Takezoe, Hideo; Aida, Takuzo

    2016-06-01

    The first design strategy that allows both memorization and modulation of the liquid-crystalline reflection color is reported. Electrophoretic deposition of a tailored ionic chiral dopant is key to realizing this unprecedented function, which may pave the way for the development of full-color e-paper that can operate without the need of color filters. PMID:27027423

  8. Fenton fragmentation for faster electrophoretic on chip purification of amplifiable genomic DNA.

    PubMed

    Hakenberg, S; Hügle, M; Meyer, P; Behrmann, O; Dame, G; Urban, G A

    2015-05-15

    With a rapid and simple actuation protocol electrophoretic nucleic acid extraction is easy automatable, requires no moving parts, is easy to miniaturize and furthermore possesses a size dependent cut-off filter adjustable by the pore size of the hydrogel. However electrophoretic nucleic acid extraction from bacteria has so far been applied mainly for short RNA targets. One of the reasons is that electrophoretic processing of unfragmented genomic DNA strands is time-consuming, because of the length. Here DNA fragmentation would accelerate extraction and isolation. We introduce on-chip lysis and non-enzymatic DNA cleavage directly followed by a purifying step for receiving amplifiable DNA fragments from bacteria in less than 25 min. In contrast to restriction enzymes the Fenton reaction is known to cleave DNA without nucleotide specificity. The reaction mix contains iron(II) EDTA, sodium ascorbate, hydrogen peroxide and lysozyme. The degree of fragmentation can be adjusted by the concentration of reagents. The results enable electrophoretic extraction methods to unspecifically process long genomic DNA in a short time frame, e.g. for pathogen detection in a lab-on-a-chip format. PMID:24970713

  9. Accurate measurement of methyl 13C chemical shifts by solid-state NMR for the determination of protein side chain conformation: the influenza a M2 transmembrane peptide as an example.

    PubMed

    Hong, Mei; Mishanina, Tatiana V; Cady, Sarah D

    2009-06-10

    The use of side chain methyl (13)C chemical shifts for the determination of the rotameric conformation of Val and Leu residues in proteins by solid-state NMR spectroscopy is described. Examination of the solution NMR stereospecifically assigned methyl groups shows significant correlation between the difference in the two methyl carbons' chemical shifts and the side chain conformation. It is found that alpha-helical and beta-sheet backbones cause different side chain methyl chemical shift trends. In alpha-helical Leu's, a relatively large absolute methyl (13)C shift difference of 2.89 ppm is found for the most populated mt rotamer (chi(1) = -60 degrees, chi(2) = 180 degrees), while a much smaller value of 0.73 ppm is found for the next populated tp rotamer (chi(1) = 180 degrees, chi(2) = 60 degrees). For alpha-helical Val residues, the dominant t rotamer (chi(1) = 180 degrees) has more downfield Cgamma2 chemical shifts than Cgamma1 by 1.71 ppm, while the next populated m rotamer (chi(1) = -60 degrees) shows the opposite trend of more downfield Cgamma1 chemical shift by 1.23 ppm. These significantly different methyl (13)C chemical shifts exist despite the likelihood of partial rotameric averaging at ambient temperature. We show that these conformation-dependent methyl (13)C chemical shifts can be utilized for side chain structure determination once the methyl (13)C resonances are accurately measured by double-quantum (DQ) filtered 2D correlation experiments, most notably the dipolar DQ to single-quantum (SQ) correlation technique. The advantage of the DQ-SQ correlation experiment over simple 2D SQ-SQ correlation experiments is demonstrated on the transmembrane peptide of the influenza A M2 proton channel. The methyl chemical shifts led to predictions of the side chain rotameric states for several Val and Leu residues in this tetrameric helical bundle. The predicted Val rotamers were further verified by dipolar correlation experiments that directly measure the chi(1

  10. High-resolution NMR spectroscopy under the fume hood.

    PubMed

    Küster, Simon K; Danieli, Ernesto; Blümich, Bernhard; Casanova, Federico

    2011-08-01

    This work reports the possibility to acquire high-resolution (1)H NMR spectra with a fist-sized NMR magnet directly installed under the fume hood. The small NMR sensor based on permanent magnets was used to monitor the trimerization of propionaldehyde catalyzed by indium trichloride in real time by continuously circulating the reaction mixture through the magnet bore in a closed loop with the help of a peristaltic pump. Thanks to the chemical selectivity of NMR spectroscopy the progress of the reaction can be monitored on-line by determining the concentrations of both reactant and product from the area under their respective lines in the NMR spectra as a function of time. This in situ measurement demonstrates that NMR probes can be used in chemistry laboratories, e.g. for reaction optimization, or installed at specific points of interest along industrial process lines. Therefore, it will open the door for the implementation of feedback control based on spectroscopic NMR data. PMID:21698335

  11. NMR Quantitation of Natural Products at the Nanomole-Scale

    PubMed Central

    Dalisay, Doralyn S.; Molinski, Tadeusz F.

    2009-01-01

    We describe a simple and accurate method for quantitation by solvent 13C-satellites (QSCS), of very small amounts of natural products using microprobe NMR spectroscopy. The method takes advantage of integration of 13C satellite peaks of deuterated solvents, in particular CDCl3, that have favorable intensities for measurements of samples in NMR microcoils and microprobe tubes in the 1–200 nanomole range. PMID:19399996

  12. Deuterium incorporation in biomass cell wall components by NMR analysis

    SciTech Connect

    Foston, Marcus B; McGaughey, Joseph; O'Neill, Hugh Michael; Evans, Barbara R; Ragauskas, Arthur J

    2012-01-01

    A commercially available deuterated kale sample was analyzed for deuterium incorporation by ionic liquid solution 2H and 1H nuclear magnetic resonance (NMR). This protocol was found to effectively measure the percent deuterium incorporation at 33%, comparable to the 31% value determined by combustion. The solution NMR technique also suggested by a qualitative analysis that deuterium is preferentially incorporated into the carbohydrate components of the kale sample.

  13. High-field 1H T1 and T2 NMR relaxation time measurements of H2O in homeopathic preparations of quartz, sulfur, and copper sulfate

    NASA Astrophysics Data System (ADS)

    Baumgartner, Stephan; Wolf, Martin; Skrabal, Peter; Bangerter, Felix; Heusser, Peter; Thurneysen, André; Wolf, Ursula

    2009-09-01

    Quantitative meta-analyses of randomized clinical trials investigating the specific therapeutic efficacy of homeopathic remedies yielded statistically significant differences compared to placebo. Since the remedies used contained mostly only very low concentrations of pharmacologically active compounds, these effects cannot be accounted for within the framework of current pharmacology. Theories to explain clinical effects of homeopathic remedies are partially based upon changes in diluent structure. To investigate the latter, we measured for the first time high-field (600/500 MHz) 1H T1 and T2 nuclear magnetic resonance relaxation times of H2O in homeopathic preparations with concurrent contamination control by inductively coupled plasma mass spectrometry (ICP-MS). Homeopathic preparations of quartz (10 c-30 c, n = 21, corresponding to iterative dilutions of 100-10-100-30), sulfur (13 x-30 x, n = 18, 10-13-10-30), and copper sulfate (11 c-30 c, n = 20, 100-11-100-30) were compared to n = 10 independent controls each (analogously agitated dilution medium) in randomized and blinded experiments. In none of the samples, the concentration of any element analyzed by ICP-MS exceeded 10 ppb. In the first measurement series (600 MHz), there was a significant increase in T1 for all samples as a function of time, and there were no significant differences between homeopathic potencies and controls. In the second measurement series (500 MHz) 1 year after preparation, we observed statistically significant increased T1 relaxation times for homeopathic sulfur preparations compared to controls. Fifteen out of 18 correlations between sample triplicates were higher for controls than for homeopathic preparations. No conclusive explanation for these phenomena can be given at present. Possible hypotheses involve differential leaching from the measurement vessel walls or a change in water molecule dynamics, i.e., in rotational correlation time and/or diffusion. Homeopathic preparations

  14. Electrophoretic Particle Guidance Significantly Enhances Olfactory Drug Delivery: A Feasibility Study

    PubMed Central

    Xi, Jinxiang; Si, Xiuhua A.; Gaide, Rachel

    2014-01-01

    Background Intranasal olfactory drug delivery provides a non-invasive method that bypasses the Blood-Brain-Barrier and directly delivers medication to the brain and spinal cord. However, a device designed specifically for olfactory delivery has not yet been found. Methods In this study, a new delivery method was proposed that utilized electrophoretic forces to guide drug particles to the olfactory region. The feasibility of this method was numerically evaluated in both idealized 2-D and anatomically accurate 3-D nose models. The influence of nasal airflow, electrode strength, and drug release position were also studied on the olfactory delivery efficiency. Findings Results showed that by applying electrophoretic forces, the dosage to the olfactory region was significantly enhanced. In both 2-D and 3-D cases, electrophoretic-guided delivery achieved olfactory dosages nearly two orders of magnitude higher than that without electrophoretic forces. Furthermore, releasing drugs into the upper half of the nostril (i.e., partial release) led to olfactory dosages two times higher than releasing drugs over the entire area of the nostril. By combining the advantages of pointed drug release and appropriate electrophoretic guidance, olfactory dosages of more than 90% were observed as compared to the extremely low olfactory dosage (<1%) with conventional inhaler devices. Conclusion Results of this study have important implications in developing personalized olfactory delivery protocols for the treatment of neurological disorders. Moreover, a high sensitivity of olfactory dosage was observed in relation to different pointed release positions, indicating the importance of precise particle guidance for effective olfactory delivery. PMID:24497957

  15. Parallel NMR spectroscopy with simultaneous detection of (1) H and (19) F nuclei.

    PubMed

    Kovacs, Helena; Kupče, Ēriks

    2016-07-01

    Recording NMR signals of several nuclear species simultaneously by using parallel receivers provides more information from a single measurement and at the same time increases the measurement sensitivity per unit time. Here we present a comprehensive series of the most frequently used NMR experiments modified for simultaneous direct detection of two of the most sensitive NMR nuclei - (1) H and (19) F. We hope that the presented material will stimulate interest in and further development of this technique. PMID:27021630

  16. NMR CHARACTERIZATIONS OF PROPERTIES OF HETEROGENEOUS MEDIA

    SciTech Connect

    C.T. Philip Chang; Changho Choi; Jeromy T. Hollenshead; Rudi Michalak; Jack Phan; Ramon Saavedra; John C. Slattery; Jinsoo Uh; Randi Valestrand; A. Ted Watson; Song Xue

    2005-01-01

    A critical and long-standing need within the petroleum industry is the specification of suitable petrophysical properties for mathematical simulation of fluid flow in petroleum reservoirs (i.e., reservoir characterization). The development of accurate reservoir characterizations is extremely challenging. Property variations may be described on many scales, and the information available from measurements reflect different scales. In fact, experiments on laboratory core samples, well-log data, well-test data, and reservoir-production data all represent information potentially valuable to reservoir characterization, yet they all reflect information about spatial variations of properties at different scales. Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) provide enormous potential for developing new descriptions and understandings of heterogeneous media. NMR has the rare capability to probe permeable media non-invasively, with spatial resolution, and it provides unique information about molecular motions and interactions that are sensitive to morphology. NMR well-logging provides the best opportunity ever to resolve permeability distributions within petroleum reservoirs. We develop MRI methods to determine, for the first time, spatially resolved distributions of porosity and permeability within permeable media samples that approach the intrinsic scale: the finest resolution of these macroscopic properties possible. To our knowledge, this is the first time that the permeability is actually resolved at a scale smaller than the sample. In order to do this, we have developed a robust method to determine of relaxation distributions from NMR experiments and a novel implementation and analysis of MRI experiments to determine the amount of fluid corresponding to imaging regions, which are in turn used to determine porosity and saturation distributions. We have developed a novel MRI experiment to determine velocity distributions within flowing experiments, and

  17. Measurement of homonuclear magnetic dipole-dipole interactions in multiple 1/2-spin systems using constant-time DQ-DRENAR NMR

    NASA Astrophysics Data System (ADS)

    Ren, Jinjun; Eckert, Hellmut

    2015-11-01

    A new pulse sequence entitled DQ-DRENAR (Double-Quantum based Dipolar Recoupling Effects Nuclear Alignment Reduction) was recently described for the quantitative measurement of magnetic dipole-dipole interactions in homonuclear spin-1/2 systems involving multiple nuclei. As described in the present manuscript, the efficiency and performance of this sequence can be significantly improved, if the measurement is done in the constant-time mode. We describe both the theoretical analysis of this method and its experimental validation of a number of crystalline model compounds, considering both symmetry-based and back-to-back (BABA) DQ-coherence excitation schemes. Based on the combination of theoretical analysis and experimental results we discuss the effect of experimental parameters such as the chemical shift anisotropy (CSA), the spinning rate, and the radio frequency field inhomogeneity upon its performance. Our results indicate that constant-time (CT-) DRENAR is a method of high efficiency and accuracy for compounds with multiple homonuclear spin systems with particular promise for the analysis of stronger-coupled and short T2 spin systems.

  18. Rheology of Blood by NMR

    NASA Astrophysics Data System (ADS)

    Han, Song-I.; Marseille, Oliver; Gehlen, Christa; Blümich, Bernhard

    2001-09-01

    Pipe flow of blood in tubes of 1 and 7 mm inner diameter, respectively, was investigated employing two-dimensional NMR velocity imaging and PFG propagator measurements at different Reynolds numbers between 10 and 3500. The results are compared to flow of a water/glycerol mixture of matching viscosity under identical conditions. The transition from laminar to turbulent flow is observed by both a flattening of the velocity profile and a change of the propagator shape. For blood flow this transition is found to be shifted toward higher Reynolds numbers as compared to the transition of the water/glycerol mixture. This observation is in agreement with predictions from hydraulic measurements and is a consequence of the non-Newtonian flow characteristics of blood as a suspension of erythrocytes and plasma. Likewise, a deviation from the laminar flow condition is observed for blood at low Reynolds numbers between 10 and 100. This phenomenon is unknown for Newtonian liquids and is explained by the onset of a geometrical arrangement of the erythrocytes, the so-called rouleaux effect.

  19. Rheology of blood by NMR.

    PubMed

    Han, S I; Marseille, O; Gehlen, C; Blümich, B

    2001-09-01

    Pipe flow of blood in tubes of 1 and 7 mm inner diameter, respectively, was investigated employing two-dimensional NMR velocity imaging and PFG propagator measurements at different Reynolds numbers between 10 and 3500. The results are compared to flow of a water/glycerol mixture of matching viscosity under identical conditions. The transition from laminar to turbulent flow is observed by both a flattening of the velocity profile and a change of the propagator shape. For blood flow this transition is found to be shifted toward higher Reynolds numbers as compared to the transition of the water/glycerol mixture. This observation is in agreement with predictions from hydraulic measurements and is a consequence of the non-Newtonian flow characteristics of blood as a suspension of erythrocytes and plasma. Likewise, a deviation from the laminar flow condition is observed for blood at low Reynolds numbers between 10 and 100. This phenomenon is unknown for Newtonian liquids and is explained by the onset of a geometrical arrangement of the erythrocytes, the so-called rouleaux effect. PMID:11531367

  20. Measurement of the lateral diffusion of dipalmitoylphosphatidylcholine adsorbed on silica beads in the absence and presence of melittin: a 31P two-dimensional exchange solid-state NMR study.

    PubMed Central

    Picard, F; Paquet, M J; Dufourc, E J; Auger, M

    1998-01-01

    31P two-dimensional exchange solid-state NMR spectroscopy was used to measure the lateral diffusion, D(L), in the fluid phase of dipalmitoylphosphatidylcholine (DPPC) in the presence and absence of melittin. The use of a spherical solid support with a radius of 320 +/- 20 nm, on which lipids and peptides are adsorbed together, and a novel way of analyzing the two-dimensional exchange patterns afforded a narrow distribution of D(L) centered at a value of (8.8 +/- 0.5) x 10(-8) cm2/s for the pure lipid system and a large distribution of D(L) spanning 1 x 10(-8) to 10 x 10(-8) cm2/s for the lipids in the presence of melittin. In addition, the determination of D(L) for nonsupported DPPC multilamellar vesicles (MLVs) suggests that the support does not slow down the lipid diffusion and that the radii of the bilayers vary from 300 to 800 nm. Finally, the DPPC-melittin complex is stabilized at the surface of the silica beads in the gel phase, opening the way to further study of the interaction between melittin and DPPC. PMID:9533697

  1. Nuclear Magnetic Resonance (NMR) analysis of a Kel-F resin and lacquer

    NASA Astrophysics Data System (ADS)

    Rutenberg, A. C.

    1985-08-01

    Proton, carbon, and fluorine nuclear magnetic resonance (NMR) spectroscopy has been used at the Oak Ridge Y-12 Plant to determine the concentration of various species present in Kel-F 800 resin and its lacquers. Nuclear magnetic resonance (NMR) spectroscopy has been used to characterize Kel-F 800 resin and to measure the various chemical species present in a lacquer based on this resin. Proton NMR spectroscopy was used to measure the ratio of ethyl acetate to xylenes and to estimate the vinylidene fluoride content of the resin. Fluorine NMR spectroscopy was used to determine the water and ethanol content of the lacquer as well as some of its components. Fluorine NMR spectroscopy was also used to estimate the amount of perfluorodecanoate emulsifier present in the Kel-F resin. Carbon-13 NMR spectroscopy was used to determine the isomeric composition of various batches of xylenes and as an alternate method for measuring the vinylidene fluoride content of the resin.

  2. Electrostatic interplay: The interaction triangle of polyamines, silicic acid, and phosphate studied through turbidity measurements, silicomolybdic acid test, and 29Si NMR spectroscopy

    PubMed Central

    Jantschke, Anne; Spinde, Katrin

    2014-01-01

    Summary The discovery of long-chain polyamines as biomolecules that are tightly associated to biosilica in diatom cell walls has inspired numerous in vitro studies aiming to characterize polyamine–silica interactions. The determination of these interactions at the molecular level is of fundamental interest on one hand for the understanding of cell wall biogenesis in diatoms and on the other hand for designing bioinspired materials synthesis approaches. The present contribution deals with the influence of amines and polyamines upon the initial self-assembly processes taking place during polyamine-mediated silica formation in solution. The influence of phosphate upon these processes is studied. For this purpose, sodium metasilicate solutions containing additives such as polyallylamine, allylamine and others in the presence/absence of phosphate were investigated. The analyses are based mainly on turbidity measurements yielding information about the early aggregation steps which finally give rise to the formation and precipitation of silica. PMID:25551030

  3. Electrostatic interplay: The interaction triangle of polyamines, silicic acid, and phosphate studied through turbidity measurements, silicomolybdic acid test, and (29)Si NMR spectroscopy.

    PubMed

    Jantschke, Anne; Spinde, Katrin; Brunner, Eike

    2014-01-01

    The discovery of long-chain polyamines as biomolecules that are tightly associated to biosilica in diatom cell walls has inspired numerous in vitro studies aiming to characterize polyamine-silica interactions. The determination of these interactions at the molecular level is of fundamental interest on one hand for the understanding of cell wall biogenesis in diatoms and on the other hand for designing bioinspired materials synthesis approaches. The present contribution deals with the influence of amines and polyamines upon the initial self-assembly processes taking place during polyamine-mediated silica formation in solution. The influence of phosphate upon these processes is studied. For this purpose, sodium metasilicate solutions containing additives such as polyallylamine, allylamine and others in the presence/absence of phosphate were investigated. The analyses are based mainly on turbidity measurements yielding information about the early aggregation steps which finally give rise to the formation and precipitation of silica. PMID:25551030

  4. NMR studies of nucleic acid dynamics

    PubMed Central

    Al-Hashimi, Hashim M.

    2014-01-01

    Nucleic acid structures have to satisfy two diametrically opposite requirements; on one hand they have to adopt well-defined 3D structures that can be specifically recognized by proteins; on the other hand, their structures must be sufficiently flexible to undergo very large conformational changes that are required during key biochemical processes, including replication, transcription, and translation. How do nucleic acids introduce flexibility into their 3D structure without losing biological specificity? Here, I describe the development and application of NMR spectroscopic techniques in my laboratory for characterizing the dynamic properties of nucleic acids that tightly integrate a broad set of NMR measurements, including residual dipolar couplings, spin relaxation, and relaxation dispersion with sample engineering and computational approaches. This approach allowed us to obtain fundamental new insights into directional flexibility in nucleic acids that enable their structures to change in a very specific functional manner. PMID:24149218

  5. Nuclear spin noise in NMR revisited

    SciTech Connect

    Ferrand, Guillaume; Luong, Michel

    2015-09-07

    The theoretical shapes of nuclear spin-noise spectra in NMR are derived by considering a receiver circuit with finite preamplifier input impedance and a transmission line between the preamplifier and the probe. Using this model, it becomes possible to reproduce all observed experimental features: variation of the NMR resonance linewidth as a function of the transmission line phase, nuclear spin-noise signals appearing as a “bump” or as a “dip” superimposed on the average electronic noise level even for a spin system and probe at the same temperature, pure in-phase Lorentzian spin-noise signals exhibiting non-vanishing frequency shifts. Extensive comparisons to experimental measurements validate the model predictions, and define the conditions for obtaining pure in-phase Lorentzian-shape nuclear spin noise with a vanishing frequency shift, in other words, the conditions for simultaneously obtaining the spin-noise and frequency-shift tuning optima.

  6. NMR studies of nucleic acid dynamics

    NASA Astrophysics Data System (ADS)

    Al-Hashimi, Hashim M.

    2013-12-01

    Nucleic acid structures have to satisfy two diametrically opposite requirements; on one hand they have to adopt well-defined 3D structures that can be specifically recognized by proteins; on the other hand, their structures must be sufficiently flexible to undergo very large conformational changes that are required during key biochemical processes, including replication, transcription, and translation. How do nucleic acids introduce flexibility into their 3D structure without losing biological specificity? Here, I describe the development and application of NMR spectroscopic techniques in my laboratory for characterizing the dynamic properties of nucleic acids that tightly integrate a broad set of NMR measurements, including residual dipolar couplings, spin relaxation, and relaxation dispersion with sample engineering and computational approaches. This approach allowed us to obtain fundamental new insights into directional flexibility in nucleic acids that enable their structures to change in a very specific functional manner.

  7. Nuclear spin noise in NMR revisited

    NASA Astrophysics Data System (ADS)

    Ferrand, Guillaume; Huber, Gaspard; Luong, Michel; Desvaux, Hervé

    2015-09-01

    The theoretical shapes of nuclear spin-noise spectra in NMR are derived by considering a receiver circuit with finite preamplifier input impedance and a transmission line between the preamplifier and the probe. Using this model, it becomes possible to reproduce all observed experimental features: variation of the NMR resonance linewidth as a function of the transmission line phase, nuclear spin-noise signals appearing as a "bump" or as a "dip" superimposed on the average electronic noise level even for a spin system and probe at the same temperature, pure in-phase Lorentzian spin-noise signals exhibiting non-vanishing frequency shifts. Extensive comparisons to experimental measurements validate the model predictions, and define the conditions for obtaining pure in-phase Lorentzian-shape nuclear spin noise with a vanishing frequency shift, in other words, the conditions for simultaneously obtaining the spin-noise and frequency-shift tuning optima.

  8. Structural Biology by NMR: Structure, Dynamics, and Interactions

    PubMed Central

    Markwick, Phineus R. L.; Malliavin, Thérèse; Nilges, Michael

    2008-01-01

    The function of bio-macromolecules is determined by both their 3D structure and conformational dynamics. These molecules are inherently flexible systems displaying a broad range of dynamics on time-scales from picoseconds to seconds. Nuclear Magnetic Resonance (NMR) spectroscopy has emerged as the method of choice for studying both protein structure and dynamics in solution. Typically, NMR experiments are sensitive both to structural features and to dynamics, and hence the measured data contain information on both. Despite major progress in both experimental approaches and computational methods, obtaining a consistent view of structure and dynamics from experimental NMR data remains a challenge. Molecular dynamics simulations have emerged as an indispensable tool in the analysis of NMR data. PMID:18818721

  9. Revisiting Protocols for the NMR Analysis of Bacterial Metabolomes

    PubMed Central

    Halouska, Steven; Zhang, Bo; Gaupp, Rosmarie; Lei, Shulei; Snell, Emily; Fenton, Robert J.; Barletta, Raul G.; Somerville, Greg A.; Powers, Robert

    2015-01-01

    Over the past decade, metabolomics has emerged as an important technique for systems biology. Measuring all the metabolites in a biological system provides an invaluable source of information to explore various cellular processes, and to investigate the impact of environmental factors and genetic modifications. Nuclear magnetic resonance (NMR) spectroscopy is an important method routinely employed in metabolomics. NMR provides comprehensive structural and quantitative information useful for metabolomics fingerprinting, chemometric analysis, metabolite identification and metabolic pathway construction. A successful metabolomics study relies on proper experimental protocols for the collection, handling, processing and analysis of metabolomics data. Critically, these protocols should eliminate or avoid biologically-irrelevant changes to the metabolome. We provide a comprehensive description of our NMR-based metabolomics procedures optimized for the analysis of bacterial metabolomes. The technical details described within this manuscript should provide a useful guide to reliably apply our NMR-based metabolomics methodology to systems biology studies. PMID:26078915

  10. Chemical shift referencing in MAS solid state NMR

    NASA Astrophysics Data System (ADS)

    Morcombe, Corey R.; Zilm, Kurt W.

    2003-06-01

    Solid state 13C magic angle spinning (MAS) NMR spectra are typically referenced externally using a probe which does not incorporate a field frequency lock. Solution NMR shifts on the other hand are more often determined with respect to an internal reference and using a deuterium based field frequency lock. Further differences arise in solution NMR of proteins and nucleic acids where both 13C and 1H shifts are referenced by recording the frequency of the 1H resonance of DSS (sodium salt of 2,2-dimethyl-2-silapentane-5-sulphonic acid) instead of TMS (tetramethylsilane). In this note we investigate the difficulties in relating shifts measured relative to TMS and DSS by these various approaches in solution and solids NMR, and calibrate adamantane as an external 13C standard for solids NMR. We find that external chemical shift referencing of magic angle spinning spectra is typically quite reproducible and accurate, with better than ±0.03 ppm accuracy being straight forward to achieve. Solid state and liquid phase NMR shifts obtained by magic angle spinning with external referencing agree with those measured using typical solution NMR hardware with the sample tube aligned with the applied field as long as magnetic susceptibility corrections and solvent shifts are taken into account. The DSS and TMS reference scales for 13C and 1H are related accurately using MAS NMR. Large solvent shifts for the 13C resonance in TMS in either deuterochloroform or methanol are observed, being +0.71 ppm and -0.74 ppm from external TMS, respectively. The ratio of the 13C resonance frequencies for the two carbons in solid adamantane to the 1H resonance of TMS is reported.

  11. Chemical shift referencing in MAS solid state NMR.

    PubMed

    Morcombe, Corey R; Zilm, Kurt W

    2003-06-01

    Solid state 13C magic angle spinning (MAS) NMR spectra are typically referenced externally using a probe which does not incorporate a field frequency lock. Solution NMR shifts on the other hand are more often determined with respect to an internal reference and using a deuterium based field frequency lock. Further differences arise in solution NMR of proteins and nucleic acids where both 13C and 1H shifts are referenced by recording the frequency of the 1H resonance of DSS (sodium salt of 2,2-dimethyl-2-silapentane-5-sulphonic acid) instead of TMS (tetramethylsilane). In this note we investigate the difficulties in relating shifts measured relative to TMS and DSS by these various approaches in solution and solids NMR, and calibrate adamantane as an external 13C standard for solids NMR. We find that external chemical shift referencing of magic angle spinning spectra is typically quite reproducible and accurate, with better than +/-0.03 ppm accuracy being straight forward to achieve. Solid state and liquid phase NMR shifts obtained by magic angle spinning with external referencing agree with those measured using typical solution NMR hardware with the sample tube aligned with the applied field as long as magnetic susceptibility corrections and solvent shifts are taken into account. The DSS and TMS reference scales for 13C and 1H are related accurately using MAS NMR. Large solvent shifts for the 13C resonance in TMS in either deuterochloroform or methanol are observed, being +0.71 ppm and -0.74 ppm from external TMS, respectively. The ratio of the 13C resonance frequencies for the two carbons in solid adamantane to the 1H resonance of TMS is reported. PMID:12810033

  12. Whole-core analysis by sup 13 C NMR

    SciTech Connect

    Vinegar, H.J.; Tutunjian, P.N. ); Edelstein, W.A.; Roemer, P.B. )

    1991-06-01

    This paper reports on a whole-core nuclear magnetic resonance (NMR) system that was used to obtain natural abundance {sup 13}C spectra. The system enables rapid, nondestructive measurements of bulk volume of movable oil, aliphatic/aromatic ratio, oil viscosity, and organic vs. carbonate carbon. {sup 13}C NMR can be used in cores where the {sup 1}H NMR spectrum is too broad to resolve oil and water resonances separately. A 5 1/4-in. {sup 13}C/{sup 1}H NMR coil was installed on a General Electric (GE) CSI-2T NMR imager/spectrometer. With a 4-in.-OD whole core, good {sup 13}C signal/noise ratio (SNR) is obtained within minutes, while {sup 1}H spectra are obtained in seconds. NMR measurements have been made of the {sup 13}C and {sup 1}H density of crude oils with a wide range of API gravities. For light- and medium-gravity oils, the {sup 13}C and {sup 1}H signal per unit volume is constant within about 3.5%. For heavy crudes, the {sup 13}C and {sup 1}H density measured by NMR is reduced by the shortening of spin-spin relaxation time. {sup 13}C and {sup 1}H NMR spin-lattice relaxation times were measured on a suite of Cannon viscosity standards, crude oils (4 to 60{degrees} API), and alkanes (C{sub 5} through C{sub 16}) with viscosities at 77{degrees}F ranging from 0.5 cp to 2.5 {times} 10{sup 7} cp. The {sup 13}C and {sup 1}H relaxation times show a similar correlation with viscosity from which oil viscosity can be estimated accurately for viscosities up to 100 cp. The {sup 13}C surface relaxation rate for oils on water-wet rocks is very low. Nonproton decoupled {sup 13}C NMR is shown to be insensitive to kerogen; thus, {sup 13}C NMR measures only the movable hydrocarbon content of the cores. In carbonates, the {sup 13}C spectrum also contains a carbonate powder pattern useful in quantifying inorganic carbon and distinguishing organic from carbonate carbon.

  13. Compact orthogonal NMR field sensor

    DOEpatents

    Gerald, II, Rex E.; Rathke, Jerome W.

    2009-02-03

    A Compact Orthogonal Field Sensor for emitting two orthogonal electro-magnetic fields in a common space. More particularly, a replacement inductor for existing NMR (Nuclear Magnetic Resonance) sensors to allow for NMR imaging. The Compact Orthogonal Field Sensor has a conductive coil and a central conductor electrically connected in series. The central conductor is at least partially surrounded by the coil. The coil and central conductor are electrically or electro-magnetically connected to a device having a means for producing or inducing a current through the coil and central conductor. The Compact Orthogonal Field Sensor can be used in NMR imaging applications to determine the position and the associated NMR spectrum of a sample within the electro-magnetic field of the central conductor.

  14. Integrative NMR for biomolecular research.

    PubMed

    Lee, Woonghee; Cornilescu, Gabriel; Dashti, Hesam; Eghbalnia, Hamid R; Tonelli, Marco; Westler, William M; Butcher, Samuel E; Henzler-Wildman, Katherine A; Markley, John L

    2016-04-01

    NMR spectroscopy is a powerful technique for determining structural and functional features of biomolecules in physiological solution as well as for observing their intermolecular interactions in real-time. However, complex steps associated with its practice have made the approach daunting for non-specialists. We introduce an NMR platform that makes biomolecular NMR spectroscopy much more accessible by integrating tools, databases, web services, and video tutorials that can be launched by simple installation of NMRFAM software packages or using a cross-platform virtual machine that can be run on any standard laptop or desktop computer. The software package can be downloaded freely from the NMRFAM software download page ( http://pine.nmrfam.wisc.edu/download_packages.html ), and detailed instructions are available from the Integrative NMR Video Tutorial page ( http://pine.nmrfam.wisc.edu/integrative.html ). PMID:27023095

  15. 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.

  16. Apparatus for direct addition of reagents into a nuclear magnetic resonance (NMR) sample in the NMR probe

    NASA Astrophysics Data System (ADS)

    Perrin, Charles L.; Rivero, Ignacio A.

    1999-04-01

    Nuclear magnetic resonance (NMR) is a widely used tool in chemistry and biochemistry. It is occasionally necessary to add small aliquots of solvents or reagents repeatedly into the NMR tube. Ordinarily this is accomplished only by ejecting the sample and carrying out the addition outside the probe. It would be preferable to add the aliquot directly into the sample. We have designed and implemented a delivery system to accomplish this. This apparatus is particularly applicable to a recent NMR titration method for measuring relative pK's and to experiments where temperature must also be varied. This apparatus provides a safe, simple, and inexpensive method for repeated aliquot addition directly into the sample in the NMR probe.

  17. Dynamic aspects of extracellular loop region as a proton release pathway of bacteriorhodopsin studied by relaxation time measurements by solid state NMR.

    PubMed

    Kawamura, Izuru; Ohmine, Masato; Tanabe, Junko; Tuzi, Satoru; Saitô, Hazime; Naito, Akira

    2007-12-01

    Local dynamics of interhelical loops in bacteriorhodopsin (bR), the extracellular BC, DE and FG, and cytoplasmic AB and CD loops, and helix B were determined on the basis of a variety of relaxation parameters for the resolved 13C and 15N signals of [1-13C]Tyr-, [15N]Pro- and [1-13C]Val-, [15N]Pro-labeled bR. Rotational echo double resonance (REDOR) filter experiments were used to assign [1-13C]Val-, [15N]Pro signals to the specific residues in bR. The previous assignments of [1-13C]Val-labeled peaks, 172.9 or 171.1 ppm, to Val69 were revised: the assignment of peak, 172.1 ppm, to Val69 was made in view of the additional information of conformation-dependent 15N chemical shifts of Pro bonded to Val in the presence of 13C-15N correlation, although no assignment of peak is feasible for 13C nuclei not bonded to Pro. 13C or 15N spin-lattice relaxation times (T1), spin-spin relaxation times under the condition of CP-MAS (T2), and cross relaxation times (TCH and TNH) for 13C and 15N nuclei and carbon or nitrogen-resolved, 1H spin-lattice relaxation times in the rotating flame (1H T1 rho) for the assigned signals were measured in [1-13C]Val-, [15N]Pro-bR. It turned out that V69-P70 in the BC loop in the extracellular side has a rigid beta-sheet in spite of longer loop and possesses large amplitude motions as revealed from 13C and 15N conformation-dependent chemical shifts and T1, T2, 1H T1 rho and cross relaxation times. In addition, breakage of the beta-sheet structure in the BC loop was seen in bacterio-opsin (bO) in the absence of retinal. PMID:18036552

  18. Optical pumping and xenon NMR

    SciTech Connect

    Raftery, M.D.

    1991-11-01

    Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping [sup 129]Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the [sup 131]Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

  19. Optical pumping and xenon NMR

    SciTech Connect

    Raftery, M.D.

    1991-11-01

    Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping {sup 129}Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the {sup 131}Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

  20. Multispectral Analysis of NMR Imagery

    NASA Technical Reports Server (NTRS)

    Butterfield, R. L.; Vannier, M. W. And Associates; Jordan, D.

    1985-01-01

    Conference paper discusses initial efforts to adapt multispectral satellite-image analysis to nuclear magnetic resonance (NMR) scans of human body. Flexibility of these techniques makes it possible to present NMR data in variety of formats, including pseudocolor composite images of pathological internal features. Techniques do not have to be greatly modified from form in which used to produce satellite maps of such Earth features as water, rock, or foliage.