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Sample records for electrophoretic nmr measurements

  1. 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.

  2. Electrophoretic Measurements of Lipid Charges in Supported Bilayers

    PubMed Central

    Poyton, Matthew F.; Cremer, Paul S.

    2013-01-01

    While electrophoresis in lipid bilayers has been performed since the 1970’s, the technique has until now been unable to accurately measure the charge on lipids and proteins within the membrane based on drift velocity measurements. Part of the problem is caused by the use of the Einstein-Smoluchowski equation to estimate the electrophoretic mobility of such species. The source of the error arises from the fact that a lipid head group is typically smaller than the Debye length of the adjacent aqueous solution in most electrophoresis experiments. Instead, the Henry equation can more accurately predict the electrophoretic mobility at sufficient ionic strength. This was done for three dye-labeled lipids with different sized head groups and a charge on each lipid of −1. Also, the charge was measured as a function of pH for two titratable lipids that were fluorescently labeled. Finally, it was shown that the Henry equation also has difficulties measuring the correct lipid charge at salt concentrations below 5 mM, where electroosmotic forces are more significant. PMID:24191728

  3. Simultaneous sizing and electrophoretic mobility measurement of sub-micron particles using Brownian motion.

    PubMed

    Palanisami, Akilan; Miller, John H

    2010-10-01

    The size and surface chemistry of micron scale particles are of fundamental importance in studies of biology and air particulate pollution. However, typical electrophoretic measurements of these and other sub-micron scale particles (300 nm-1 μm) cannot resolve size information within heterogeneous mixtures unambiguously. Using optical microscopy, we monitor electrophoretic motion together with the Brownian velocity fluctuations - using the latter to measure size by either the Green-Kubo relation or by calibration from known size standards. Particle diameters are resolved to ±12% with 95% confidence. Strikingly, the size resolution improves as the particle size decreases due to the increased Brownian motion. The sizing ability of the Brownian assessed electrophoresis method described here complements the electrophoretic mobility resolution of the traditional CE. PMID:20882556

  4. NMR Measures of Heterogeneity Length

    NASA Astrophysics Data System (ADS)

    Spiess, Hans W.

    2002-03-01

    Advanced solid state NMR spectroscopy provides a wealth of information about structure and dynamics of complex systems. On a local scale, multidimensional solid state NMR has elucidated the geometry and the time scale of segmental motions at the glass transition. The higher order correlation functions which are provided by this technique led to the notion of dynamic heterogeneities, which have been characterized in detail with respect to their rate memory and length scale. In polymeric and low molar mass glass formers of different fragility, length scales in the range 2 to 4 nm are observed. In polymeric systems, incompatibility of backbone and side groups as in polyalkylmethacrylates leads to heteogeneities on the nm scale, which manifest themselves in unusual chain dynamics at the glass transition involving extended chain conformations. References: K. Schmidt-Rohr and H.W. Spiess, Multidimensional Solid-State NMR and Polymers,Academic Press, London (1994). U. Tracht, M. Wilhelm, A. Heuer, H. Feng, K. Schmidt-Rohr, H.W. Spiess, Phys. Rev. Lett. 81, 2727 (1998). S.A. Reinsberg, X.H. Qiu, M. Wilhelm, M.D. Ediger, H.W. Spiess, J.Chem.Phys. 114, 7299 (2001). S.A. Reinsberg, A. Heuer, B. Doliwa, H. Zimmermann, H.W. Spiess, J. Non-Crystal. Solids, in press (2002)

  5. Ligand-substitution mode capillary electrophoretic reactor: extending capillary electrophoretic reactor toward measurement of slow dissociation kinetics with a half-life of hours.

    PubMed

    Iki, Nobuhiko; Takahashi, Mariko; Takahashi, Toru; Hoshino, Hitoshi

    2009-09-15

    A method employing capillary electrophoresis (CE) was developed to determine the rate constant of the very slow spontaneous dissociation of a complex species. The method uses a CE reactor (CER) to electrophoretically separate components from a complex zone and, thus, spontaneously dissociate a complex. The dissociation is accelerated by ligand substitution (LS) involving a competing ligand added to the electrophoretic buffer. The LS-CER method is validated using the dissociation of a Ti(IV)-catechin complex and EDTA as a competing ligand. There is good agreement between the spontaneous dissociation rate constant (k(d) = (1.64 +/- 0.63) x 10(-4) s(-1)) and the rate constant obtained by a conventional batchwise LS reaction (k(d) = (1.43 +/- 0.04) x 10(-4) s(-1)). Furthermore, the usefulness of the method is demonstrated using a Ti(IV)-tiron complex, for which k(d) = (0.51 +/- 0.43) x 10(-4) s(-1), corresponding to a half-life (t(1/2)) of 3.8 h. Notably, a single run of LS-CER for the Ti(IV) complex is completed within 40 min, implying that LS-CER requires a considerably shorter measurement time (roughly equal to t(1/2)) than conventional CER. LS-CER can be widely applied to determine the spontaneous dissociation rates of inorganic diagnostic and therapeutic reagents as well as of biomolecular complexes.

  6. 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

  7. NMR measurements of intracellular ions in hypertension

    NASA Astrophysics Data System (ADS)

    Veniero, Joseph C.; Gupta, R. K.

    1993-08-01

    The NMR methods for the measurement of intracellular free Na+, K+, Mg2+, Ca2+, and H+ are introduced. The recent literature is then presented showing applications of these methods to cells and tissues from hypertensive animal model systems, and humans with essential hypertension. The results support the hypothesis of consistent derangement of the intracellular ionic environment in hypertension. The theory that this derangement may be a common link in the disease states of high blood pressure and abnormal insulin and glucose metabolism, which are often associated clinically, is discussed.

  8. 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;…

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  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. 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.

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

    DOE PAGES

    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

  16. Rate of lateral diffusion of intramembrane particles: measurement by electrophoretic displacement and rerandomization.

    PubMed Central

    Sowers, A E; Hackenbrock, C R

    1981-01-01

    A method combining electrophoresis and freeze-fracture electron microscopy is described; the method was used to determine the lateral diffusion coefficient of intramembrane particles (integral proteins) in the mitochondrial inner membrane. An electric current was passed through microsuspensions of purified, spherical inner membranes at pH 7.4, which caused an electrophoretic migration of intramembrane particles in the membrane plane into a single, crowded patch facing the positive electrode. The membrane microsuspensions were quick-frozen at specified times after the packed particles were released from the electrophoretic force and while the particles were diffusing back to a random distribution. Observed concentration gradients of intramembrane particles during this time were quantitatively compared with and found to follow a mathematical model for Fickian diffusion of particles on a spherical membrane. The results determine the kinetics of free diffusion of integral proteins at the resolution of individual proteins. The diffusion coefficient of the integral proteins in the mitochondrial inner membrane was determined to be 8.3 X 10(-10) cm2/sec at 20 degrees C, from which a root-mean-square displacement of 57 nm in 10 msec is predicted. Images PMID:6947228

  17. 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.

  18. Using electrophoretic mobility shift assays to measure equilibrium dissociation constants: GAL4-p53 binding DNA as a model system.

    PubMed

    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(D) ) for a protein/DNA interaction using electrophoretic mobility shift assays (EMSAs). An EMSA monitors the migration of DNA through a native gel; the DNA migrates more slowly when bound to a protein. To determine a K(D) the amount of unbound and protein-bound DNA in the gel is measured as the protein concentration increases. By performing this experiment, students will be introduced to making affinity measurements and gain experience in performing quantitative EMSAs. The experiment describes measuring the K(D) for the interaction between the chimeric protein GAL4-p53 and its DNA recognition site; however, the techniques are adaptable to other DNA binding proteins. In addition, the basic experiment described can be easily expanded to include additional inquiry-driven experimentation. © 2012 by The International Union of Biochemistry and Molecular Biology.

  19. 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...

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  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. Measurement of fibrin concentration by fast field-cycling NMR.

    PubMed

    Broche, Lionel M; Ismail, Saadiya R; Booth, Nuala A; Lurie, David J

    2012-05-01

    The relaxation of (1)H nuclei due to their interaction with quadrupolar (14)N nuclei in gel structures is measured using fast field-cycling NMR. This phenomenon called quadrupolar dips has been reported in different (1)H-(14)N bond-rich species. In this study, we have studied quadrupolar dips in fibrin, an insoluble protein that is the core matrix of thrombi. Fibrin was formed by the addition of thrombin to fibrinogen in 0.2% agarose gel. T(1)-dispersion curves were measured using fast field-cycling NMR relaxometry, over the field range of 1.5-3.5 MHz (proton Larmor frequency), and were analyzed using a curve-fitting algorithm. A linear increase of signal amplitude with increasing fibrin concentration was observed. This agrees with the current theory that predicts a linear relationship of signal amplitude with the concentration of contributing (14)N spins in the sample. Interestingly, fibrin formation gave rise to the signal, regardless of crosslinking induced by the transglutaminase factor XIIIa. To investigate the effect of proteins that might be trapped in the thrombi in vivo, the plasma protein albumin was added to the fibrin gel, and an increase in the quadrupolar signal amplitude was observed. This study can potentially be useful for thrombi classification by fast field-cycling MRI techniques.

  8. Systematic bias in NMR diffusion measurements on polydisperse systems

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoyue; Xu, Kaipin; Zhang, Shanmin

    2015-03-01

    Least-squares fitting of the Stejskal-Tanner equation is a routine process in the measurement of molecular diffusion coefficient (MDC) using Nuclear Magnetic Resonance (NMR) Spectroscopy. It is simple and elegant. However, a bias of the MDC is noticed when the system is polydispersed. This is due to improper accounts of the diffusion coefficient distribution. Eventually, it leads to a discrepancy between the observed MDC and the statistical mean value of the distribution. To reveal the discrepancy, an analytical solution is derived when the diffusion data is taken a logarithmic linearization. Computer simulation is also applied to obtain a non-linear regression result. For a Gaussian distribution of the MDCs, the bias is proportional to the square of the distribution width (linear regression), but it is also inversely proportional to the statistical mean value of the distribution (non-linear regression). This indicates that the MDC derived from Stejskal-Tanner equation only holds well for narrow distribution of MDCs. Otherwise, molecular radius derived from the Stokes-Einstein equation needs to be reconsidered due to the incorrect estimation of the MDC.

  9. Systematic bias in NMR diffusion measurements on polydisperse systems.

    PubMed

    Zhou, Xiaoyue; Xu, Kaipin; Zhang, Shanmin

    2015-03-01

    Least-squares fitting of the Stejskal-Tanner equation is a routine process in the measurement of molecular diffusion coefficient (MDC) using Nuclear Magnetic Resonance (NMR) Spectroscopy. It is simple and elegant. However, a bias of the MDC is noticed when the system is polydispersed. This is due to improper accounts of the diffusion coefficient distribution. Eventually, it leads to a discrepancy between the observed MDC and the statistical mean value of the distribution. To reveal the discrepancy, an analytical solution is derived when the diffusion data is taken a logarithmic linearization. Computer simulation is also applied to obtain a non-linear regression result. For a Gaussian distribution of the MDCs, the bias is proportional to the square of the distribution width (linear regression), but it is also inversely proportional to the statistical mean value of the distribution (non-linear regression). This indicates that the MDC derived from Stejskal-Tanner equation only holds well for narrow distribution of MDCs. Otherwise, molecular radius derived from the Stokes-Einstein equation needs to be reconsidered due to the incorrect estimation of the MDC.

  10. 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.

  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. Measurement of longitudinal relaxation times in crowded 1H NMR spectra using one- and two-dimensional maximum quantum (MAXY) NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Maili; Ye, Chaohui; Farrant, R. Duncan; Nicholson, Jeremy K.; Lindon, John C.

    Methods for measuring longitudinal relaxation times of protons in heavily overlapped 1H NMR spectra are introduced and exemplified using a solution of cholesteryl acetate. The methods are based on 1-dimensional and 2-dimensional maximum quantum NMR spectroscopy (MAXY), which makes possible the selective detection of CH, CH2 and CH31H NMR resonances. A modification of the BIRD pulse sequence to achieve selective inversion of protons bonded to either 12C or 13C is given. The approach should find application in studies of molecular dynamics where isotopic enrichment is not possible and the level of available sample dictates the use of 1H NMR spectroscopy.

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

    PubMed

    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.

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

    PubMed

    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. PMID:2645693

  16. 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.

  17. Ultra-low-field NMR relaxation and diffusion measurements using an optical magnetometer.

    PubMed

    Ganssle, Paul J; Shin, Hyun D; Seltzer, Scott J; Bajaj, Vikram S; Ledbetter, Micah P; Budker, Dmitry; Knappe, Svenja; Kitching, John; Pines, Alexander

    2014-09-01

    Nuclear magnetic resonance (NMR) relaxometry and diffusometry are important tools for the characterization of heterogeneous materials and porous media, with applications including medical imaging, food characterization and oil-well logging. These methods can be extremely effective in applications where high-resolution NMR is either unnecessary, impractical, or both, as is the case in the emerging field of portable chemical characterization. Here, we present a proof-of-concept experiment demonstrating the use of high-sensitivity optical magnetometers as detectors for ultra-low-field NMR relaxation and diffusion measurements.

  18. NMR measurements in a hydrogen/helium slush at 4.2 K

    NASA Astrophysics Data System (ADS)

    Matusiak, Marcin; Hamida, Jaha; Ihas, Gary G.; Sullivan, Neil

    2003-03-01

    Matrix isolation of various atoms in solid hydrogen presents both pure and applied research possibilities. When single atom properties are measured with NMR in the background of a quantum solid, insight into electronic interactions and quantum diffusion may be obtained. A cell has been constructed which, when filled with liquid helium, may have various gases injected into it. If this gas is a mixture of hydrogen and, say, boron, NMR may be performed on both the H and the B nuclei. Crystal or amorphous structures and atomic diffusion may be investigated. Design and construction of the apparatus will be presented. The first pulsed NMR data on H will be presented and interpreted.

  19. 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

  20. J-GFT NMR for precise measurement of mutually correlated nuclear spin-spin couplings.

    PubMed

    Atreya, Hanudatta S; Garcia, Erwin; Shen, Yang; Szyperski, Thomas

    2007-01-24

    G-matrix Fourier transform (GFT) NMR spectroscopy is presented for accurate and precise measurement of chemical shifts and nuclear spin-spin couplings correlated according to spin system. The new approach, named "J-GFT NMR", is based on a largely extended GFT NMR formalism and promises to have a broad impact on projection NMR spectroscopy. Specifically, constant-time J-GFT (6,2)D (HA-CA-CO)-N-HN was implemented for simultaneous measurement of five mutually correlated NMR parameters, that is, 15N backbone chemical shifts and the four one-bond spin-spin couplings 13Calpha-1Halpha, 13Calpha-13C', 15N-13C', and 15N-1HNu. The experiment was applied for measuring residual dipolar couplings (RDCs) in an 8 kDa protein Z-domain aligned with Pf1 phages. Comparison with RDC values extracted from conventional NMR experiments reveals that RDCs are measured with high precision and accuracy, which is attributable to the facts that (i) the use of constant time evolution ensures that signals do not broaden whenever multiple RDCs are jointly measured in a single dimension and (ii) RDCs are multiply encoded in the multiplets arising from the joint sampling. This corresponds to measuring the couplings multiple times in a statistically independent manner. A key feature of J-GFT NMR, i.e., the correlation of couplings according to spin systems without reference to sequential resonance assignments, promises to be particularly valuable for rapid identification of backbone conformation and classification of protein fold families on the basis of statistical analysis of dipolar couplings.

  1. NMR measurement of hydrodynamic dispersion in porous media subject to biofilm mediated precipitation reactions.

    PubMed

    Fridjonsson, Einar O; Seymour, Joseph D; Schultz, Logan N; Gerlach, Robin; Cunningham, Alfred B; Codd, Sarah L

    2011-03-01

    Noninvasive measurements of hydrodynamic dispersion by nuclear magnetic resonance (NMR) are made in a model porous system before and after a biologically mediated precipitation reaction. Traditional magnetic resonance imaging (MRI) was unable to detect the small scale changes in pore structure visualized during light microscopy analysis after destructive sampling of the porous medium. However, pulse gradient spin echo nuclear magnetic resonance (PGSE NMR) measurements clearly indicated a change in hydrodynamics including increased pore scale mixing. These changes were detected through time-dependent measurement of the propagator by PGSE NMR. The dynamics indicate an increased pore scale mixing which alters the preasymptotic approach to asymptotic Gaussian dynamics governed by the advection diffusion equation. The methods described here can be used in the future to directly measure the transport of solutes in biomineral-affected porous media and contribute towards reactive transport models, which take into account the influence of pore scale changes in hydrodynamics.

  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. 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...

  4. 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 ...

  5. Measurement of pH by NMR Spectroscopy in Concentrated Aqueous Fluoride Buffers

    PubMed Central

    Gerken, James B.

    2010-01-01

    An NMR spectroscopic technique has been developed to give rapid, accurate pH measurements on tenth-milliliter samples of concentrated acidic aqueous solutions buffered by fluoride ion in the pH 1.5 – 4.5 range. The fluoride 19F chemical shift has been calibrated as a function of pH at 0.1 and 1.0 M concentration by reference to an internal 3-fluoropyridine standard. Subsequent measurements of fluoride buffer pH required no additives and only two NMR spectra in the presence of an external reference standard. PMID:21278857

  6. Estimation and measurement of flat or solenoidal coil inductance for radiofrequency NMR coil design.

    PubMed

    Rainey, Jan K; DeVries, Jeffrey S; Sykes, Brian D

    2007-07-01

    The inductance of a radiofrequency coil determines its compatibility with a given NMR probe circuit. However, calculation (or estimation) of inductance for radiofrequency coils of dimensions suitable for use in an NMR probe is not trivial, particularly for flat-coils. A comparison of a number of formulae for calculation of inductance is presented through the use of a straightforward inductance measurement circuit. This technique relies upon instrumentation available in many NMR laboratories rather than upon more expensive and specialized instrumentation often utilized in the literature. Inductance estimation methods are suggested and validated for both flat-coils and solenoids. These have proven very useful for fabrication of a number of new coils in our laboratory for use in static solid-state NMR probes operating at (1)H frequencies of 300 and 600MHz. Solenoidal coils with very similar measured and estimated inductances having inner diameters from 1 to 5mm are directly compared as an example of the practical application of inductance estimation for interchange of coils within an existing solid-state NMR probe.

  7. 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.

  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. An introduction to NMR-based approaches for measuring protein dynamics

    PubMed Central

    Kleckner, Ian R; Foster, Mark P

    2010-01-01

    Proteins are inherently flexible at ambient temperature. At equilibrium, they are characterized by a set of conformations that undergo continuous exchange within a hierarchy of spatial and temporal scales ranging from nanometers to micrometers and femtoseconds to hours. Dynamic properties of proteins are essential for describing the structural bases of their biological functions including catalysis, binding, regulation and cellular structure. Nuclear magnetic resonance (NMR) spectroscopy represents a powerful technique for measuring these essential features of proteins. Here we provide an introduction to NMR-based approaches for studying protein dynamics, highlighting eight distinct methods with recent examples, contextualized within a common experimental and analytical framework. The selected methods are (1) Real-time NMR, (2) Exchange spectroscopy, (3) Lineshape analysis, (4) CPMG relaxation dispersion, (5) Rotating frame relaxation dispersion, (6) Nuclear spin relaxation, (7) Residual dipolar coupling, (8) Paramagnetic relaxation enhancement. PMID:21059410

  10. 1H NMR and calorimetric measurements on rabbit eye lenses.

    PubMed

    Gutsze, A; Bodurka, J; Olechnowicz, R; Buntkowsky, G; Limbach, H H

    1995-01-01

    The dynamic properties of water molecules in the rabbit lens were studied by proton nuclear magnetic resonance line shape analysis, measurements of relaxation times as a function of temperature and calorimetric measurements. The experiments prove, as already suggested by other authors, that there are two types of water in the lens of rabbit eyes, namely bound unfreezable hydration water and bulk freezable water. Line shape analysis and relaxometry showed, that this two types of water exist in two different environments, which may be identified as the nucleus and the cortex of the lens. The line shape analysis showed furthermore that water molecules in the rabbit lens has a common spin lattice relaxation time (T1), but two different transverse relaxation times (T2A and T2B). The tentative model of fast water exchange on the T1 time scale and slow water exchange on the T2 time scale, was used to explain experimental proton relaxation data of the rabbit lens. An estimation for this exchange rate kex by comparing it to the relaxation times is given (T1(-1) < kex < T1(-1)). It has also been shown by a calorimetric measurements, that the lenses can be easily under-cooled to temperatures well below the freezing point of water. The achievable maximum undercooling temperature of the lens is a function of the cooling rate KC, therefore it has to be considered as an experimentally adjustable parameter which is not characteristic for the investigated sample. Thus it must be noted that any previous discussions about the specific value of the temperature of water crystallisation in biological systems need to be carefully reconsidered.

  11. Equilibrium exchange of dimethyl methylphosphonate across the human red cell membrane measured using NMR spin transfer

    NASA Astrophysics Data System (ADS)

    Kirk, Kiaran; Kuchel, Philip W.

    The 31P NMR spectrum of dimethyl methylphosphonate, in a suspension of human erythrocytes in a hypertonic medium, is characterized by separate intra- and extracellular resonances. The compound crosses the red cell membrane too rapidly for its transport to be monitored using conventional NMR time-course techniques. In the present work we adapted the saturation transfer method to measure the unidirectional flux of dimethyl methylphosphonate into the cell at equilibrium and thereby gained an estimate of its permeability coefficient. Repeated measurements on low hematocrit cell suspensions showed no significant variation in the permeability coefficients for cells from five different donors. Saturation transfer measurements conducted over a range of hematocrits demonstrated the hematocrit dependence of the unidirectional rate constant for dimethyl methylphosphonate influx. The calculated permeability coefficient was independent of hematocrit.

  12. Electrophoretic deposition of biomaterials.

    PubMed

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

    2010-10-01

    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.

  13. 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

  14. Measurement and Imaging of Planar Electromagnetic Phantoms Based on NMR Imaging Methods

    NASA Astrophysics Data System (ADS)

    Frollo, I.; Andris, P.; Přibil, J.; Vojtíšek, L.; Dermek, T.; Valkovič, L.

    2010-01-01

    Planar electromagnetic phantom design for measurement and imaging using NMR has been performed. Electromagnetic phantom computation and testing on a NMR 0.178 Tesla Esaote Opera imager were accomplished. The classical geometrical and chemical phantoms are generally used for testing of NMR imaging systems. They are simple cylindrical or rectangular objects with different dimensions and shapes with holes filled with specially prepared water solutions. In our experiments a homogeneous phantom (reference medium) - a container filled with water - was used. The resultant image represents the magnetic field distribution in the homogeneous phantom. An image acquired by this method is actually a projection of the sample properties onto the homogeneous phantom. The goal of the paper is to map and image the magnetic field deformation using NMR imaging methods. We are using a double slender rectangular vessel with constant thickness filled with specially prepared water solution in our experiments. For detection a carefully tailored gradient-echo imaging method, susceptible to magnetic field homogeneity, was used.

  15. Are Protein Force Fields Getting Better? A Systematic Benchmark on 524 Diverse NMR Measurements.

    PubMed

    Beauchamp, Kyle A; Lin, Yu-Shan; Das, Rhiju; Pande, Vijay S

    2012-04-10

    Recent hardware and software advances have enabled simulation studies of protein systems on biophysically-relevant timescales, often revealing the need for improved force fields. Although early force field development was limited by the lack of direct comparisons between simulation and experiment, recent work from several labs has demonstrated direct calculation of NMR observables from protein simulations. Here we quantitatively evaluate recent molecular dynamics force fields against a suite of 524 chemical shift and J coupling ((3)JH(N)H(α), (3)JH(N)C(β), (3)JH(α)C', (3)JH(N)C', and (3)JH(α)N) measurements on dipeptides, tripeptides, tetra-alanine, and ubiquitin. Of the force fields examined (ff96, ff99, ff03, ff03*, ff03w, ff99sb*, ff99sb-ildn, ff99sb-ildn-phi, ff99sb-ildn-nmr, CHARMM27, OPLS-AA), two force fields (ff99sb-ildn-phi, ff99sb-ildn-nmr) combining recent side chain and backbone torsion modifications achieve high accuracy in our benchmark. For the two optimal force fields, the calculation error is comparable to the uncertainty in the experimental comparison. This observation suggests that extracting additional force field improvements from NMR data may require increased accuracy in J coupling and chemical shift prediction. To further investigate the limitations of current force fields, we also consider conformational populations of dipeptides, which were recently estimated using vibrational spectroscopy.

  16. 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.

  17. 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.

  18. Discriminating between Lüders and von Neumann measuring devices: An NMR investigation

    NASA Astrophysics Data System (ADS)

    Sudheer Kumar, C. S.; Shukla, Abhishek; Mahesh, T. S.

    2016-10-01

    Quantum state after measuring a degenerate observable is given by Lüders and von Neumann state update rules. While the former preserves superpositions, the latter does not. Even though both rules are valid and realizable, which rule a given measuring device ("Black Box") obeys, depends on its internal details. Recently Hegerfeldt and Mayato (2012) [5] had formulated a protocol to discriminate between the two kinds of measuring devices. Here we have reformulated this protocol for system and measuring qubits. We then experimentally investigated this protocol on an NMR spectrometer, and found that Lüders rule is favoured.

  19. Measurements of heavy-atom isotope effects using 1H NMR spectroscopy.

    PubMed

    Pabis, Anna; Kamiński, Rafał; Ciepielowski, Grzegorz; Jankowski, Stefan; Paneth, Piotr

    2011-10-01

    A novel method for measuring heavy-atom KIEs for magnetically active isotopes using (1)H NMR is presented. It takes advantage of the resonance split of the protons coupled with the heavy atom in the (1)H spectrum. The method is validated by the example of the (13)C-KIE on the hydroamination of styrene with aniline, catalyzed by phosphine-ligated palladium triflates.

  20. An improved technique for computing permeability from NMR measurements in mudstones

    NASA Astrophysics Data System (ADS)

    Daigle, Hugh; Dugan, Brandon

    2011-08-01

    We develop a technique for extending nuclear magnetic resonance (NMR) permeability estimation to clay-rich sediments. Our technique builds on the Schlumberger-Doll Research (SDR) equation by using porosity, grain size, specific surface, and magnetic susceptibility data to yield more accurate permeability estimation in mudstones with large pore surface areas and complex mineralogies. Based on measurements of natural sediments as well as resedimented laboratory mixtures of silica, bentonite, and kaolinite powders, we find that our method predicts permeability values that match measured values over four orders of magnitude and among lithologies that vary widely in grain size, mineralogy, and surface area. Our results show that the relationship between NMR data and permeability is a function of mineralogy and grain geometry, and that permeability predictions in clay-rich sediments can be improved with insights regarding the nature of the pore system made by the Kozeny theory. This technique extends the utility of NMR measurements beyond typical reservoir-quality rocks to a wide range of lithologies.

  1. 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

  2. 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

  3. 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.

  4. Mechanism of decreased NMR-measured free magnesium in stored erythrocytes

    SciTech Connect

    Bock, J.L.; Wenz, B.; Gupta, R.K.

    1986-05-01

    P-31 NMR spectra of ebythrocytes stored with standard preservation media (ACD or CPDA-1) show a progressive upfield shift of the ..beta..P resonance of ATP. This would seem to indicate lower Mg-saturation of ATP and hence lower intracellular free magnesium (Mg/sub i/), but total intracellular Mg measured by AAS does not change. The authors have now observed similar spectral changes in erythrocytes stored in citrate-free media, hence the shifts are not an effect of citrate. Acidifying fresh blood to mimic the pH changes that occur with storage did not induce comparable shifts, nor did treatment of fresh blood with gramicidin, which causes Na/K redistribution across the erythrocyte membrane similar to that occurring with storage. The shifts were largely reversed when stored cells were incubated at 37/sup 0/C for 1 hr with fresh citrated or heparinized plasma. Such incubation also increased ATP levels but did not increased 2,3-DPG, hence the shifts do not depend on disappearance of 2,3-DPG. P-31 NMR of acid extracts of stored cells show accumulation of some pyrophosphate, but probably not enough to account for the large apparent decreased in Mg/sub i/. The NMR estimation of decreased Mg/sub i/ in stored blood does not appear to be an artifact related to alterations in monovalent cations or in binding of ligands to hemoglobin. A possible mechanism is increased binding of Mg to the cell membrane.

  5. Noninvasive measurements of glycogen in perfused mouse livers using chemical exchange saturation transfer NMR and comparison to (13)C NMR spectroscopy.

    PubMed

    Miller, Corin O; Cao, Jin; Chekmenev, Eduard Y; Damon, Bruce M; Cherrington, Alan D; Gore, John C

    2015-06-01

    Liver glycogen represents an important physiological form of energy storage. It plays a key role in the regulation of blood glucose concentrations, and dysregulations in hepatic glycogen metabolism are linked to many diseases including diabetes and insulin resistance. In this work, we develop, optimize, and validate a noninvasive protocol to measure glycogen levels in isolated perfused mouse livers using chemical exchange saturation transfer (CEST) NMR spectroscopy. Model glycogen solutions were used to determine optimal saturation pulse parameters which were then applied to intact perfused mouse livers of varying glycogen content. Glycogen measurements from serially acquired CEST Z-spectra of livers were compared with measurements from interleaved natural abundance (13)C NMR spectra. Experimental data revealed that CEST-based glycogen measurements were highly correlated with (13)C NMR glycogen spectra. Monte Carlo simulations were then used to investigate the inherent (i.e., signal-to-noise-based) errors in the quantification of glycogen with each technique. This revealed that CEST was intrinsically more precise than (13)C NMR, although in practice may be prone to other errors induced by variations in experimental conditions. We also observed that the CEST signal from glycogen in liver was significantly less than that observed from identical amounts in solution. Our results demonstrate that CEST provides an accurate, precise, and readily accessible method to noninvasively measure liver glycogen levels and their changes. Furthermore, this technique can be used to map glycogen distributions via conventional proton magnetic resonance imaging, a capability universally available on clinical and preclinical magnetic resonance imaging (MRI) scanners vs (13)C detection, which is limited to a small fraction of clinical-scale MRI scanners. PMID:25946616

  6. Noninvasive measurements of glycogen in perfused mouse livers using chemical exchange saturation transfer NMR and comparison to (13)C NMR spectroscopy.

    PubMed

    Miller, Corin O; Cao, Jin; Chekmenev, Eduard Y; Damon, Bruce M; Cherrington, Alan D; Gore, John C

    2015-06-01

    Liver glycogen represents an important physiological form of energy storage. It plays a key role in the regulation of blood glucose concentrations, and dysregulations in hepatic glycogen metabolism are linked to many diseases including diabetes and insulin resistance. In this work, we develop, optimize, and validate a noninvasive protocol to measure glycogen levels in isolated perfused mouse livers using chemical exchange saturation transfer (CEST) NMR spectroscopy. Model glycogen solutions were used to determine optimal saturation pulse parameters which were then applied to intact perfused mouse livers of varying glycogen content. Glycogen measurements from serially acquired CEST Z-spectra of livers were compared with measurements from interleaved natural abundance (13)C NMR spectra. Experimental data revealed that CEST-based glycogen measurements were highly correlated with (13)C NMR glycogen spectra. Monte Carlo simulations were then used to investigate the inherent (i.e., signal-to-noise-based) errors in the quantification of glycogen with each technique. This revealed that CEST was intrinsically more precise than (13)C NMR, although in practice may be prone to other errors induced by variations in experimental conditions. We also observed that the CEST signal from glycogen in liver was significantly less than that observed from identical amounts in solution. Our results demonstrate that CEST provides an accurate, precise, and readily accessible method to noninvasively measure liver glycogen levels and their changes. Furthermore, this technique can be used to map glycogen distributions via conventional proton magnetic resonance imaging, a capability universally available on clinical and preclinical magnetic resonance imaging (MRI) scanners vs (13)C detection, which is limited to a small fraction of clinical-scale MRI scanners.

  7. 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

  8. 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.

  9. 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.

  10. Magnetism in CeRhIn5 at high fields measured by NMR

    NASA Astrophysics Data System (ADS)

    Mounce, A. M.; Ronning, F.; Bauer, E. D.; Thompson, J. D.; Reyes, A. P.; Kuhns, P. L.

    2015-03-01

    De Haas-van Alphen measurements of CeRhIn5 at ambient pressure show an abrupt change in the Fermi surface volume at high fields, H* ~ 30 T, and low temperatures resulting in antiferromagnetic phases with a small Fermi surface at fields below H* and a large Fermi surface at fields H such that H* < H < 50 T. Nuclear magnetic resonance (NMR) is the ideal probe for these magnetic states as the microscopic details are still lacking. Our preliminary NMR measurements find the magnetic order for H ∥ c is incommensurate up to 30 T as opposed to H ⊥ c which transitions from incommensurate to commensurate at H ~ 2 T. Furthermore, we find that the magnetic moment decreases near 17 T for H ∥ c . These measurements provide an insight into the magnetic anisotropy of CeRhIn5 and are a crucial step to studying its high field phases. Work at Los Alamos was performed under the auspices of the U.S. DOE, Office of Basic Energy Science, Division of Materials and Engineering.

  11. High-resolution 2D NMR spectroscopy of bicelles to measure the membrane interaction of ligands.

    PubMed

    Dvinskikh, Sergey V; Dürr, Ulrich H N; Yamamoto, Kazutoshi; Ramamoorthy, Ayyalusamy

    2007-01-31

    Magnetically aligned bicelles are increasingly being used as model membranes in solution- and solid-state NMR studies of the structure, dynamics, topology, and interaction of membrane-associated peptides and proteins. These studies commonly utilize the PISEMA pulse sequence to measure dipolar coupling and chemical shift, the two key parameters used in subsequent structural analysis. In the present study, we demonstrate that the PISEMA and other rotating-frame pulse sequences are not suitable for the measurement of long-range heteronuclear dipolar couplings, and that they provide inaccurate values when multiple protons are coupled to a 13C nucleus. Furthermore, we demonstrate that a laboratory-frame separated-local-field experiment is capable of overcoming these difficulties in magnetically aligned bicelles. An extension of this approach to accurately measure 13C-31P and 1H-31P couplings from phospholipids, which are useful to understand the interaction of molecules with the membrane, is also described. In these 2D experiments, natural abundance 13C was observed from bicelles containing DMPC and DHPC lipid molecules. As a first application, these solid-state NMR approaches were utilized to probe the membrane interaction of an antidepressant molecule, desipramine, and its location in the membrane.

  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. Measuring JHH values with a selective constant-time 2D NMR protocol

    NASA Astrophysics Data System (ADS)

    Lin, Liangjie; Wei, Zhiliang; Lin, Yanqin; Chen, Zhong

    2016-11-01

    Proton-proton scalar couplings play important roles in molecule structure elucidation. However, measurements of JHH values in complex coupled spin systems remain challenging. In this study, we develop a selective constant-time (SECT) 2D NMR protocol with which scalar coupling networks involving chosen protons can be revealed, and corresponding JHH values can be measured through doublets along the F1 dimension. All JHH values within a network of n fully coupled protons can be separately determined with (n - 1) SECT experiments. Additionally, the proposed pulse sequence possesses satisfactory sensitivity and handy implementation. Therefore, it will interest scientists who intend to address structural analyzes of molecules with overcrowded spectra, and may greatly facilitate the applications of scalar-coupling constants in molecule structure studies.

  14. On the noninvasive measurement of intracellular free magnesium by 31P NMR spectroscopy.

    PubMed

    Gupta, R K; Gupta, P; Yushok, W D; Rose, Z B

    1983-01-01

    We previously introduced a noninvasive measurement of the concentration of free Mg2+ in intact cells and tissues using 31P NMR. To resolve a controversy in the literature concerning the affinity of Mg2+ for ATP used in our procedure, the apparent dissociation constant of MgATP under simulated intracellular conditions has been determined by three independent magnetic resonance methods, including a newly developed combination procedure for determining this value at intracellular ATP levels. The new combination method, which utilizes 31P NMR to determine the degree of Mg2+ chelation of ATP and the dye antipyrylazo III for optical determination of free Mg2+, yielded a value of (50 +/- 10) microM for this apparent dissociation constant at pH 7.2 in the presence of 0.15 M K+ and 25 degrees C. We further show that hydroxyquinolines are not satisfactory indicators for optical determination of the Mg2+-nucleotide dissociation constant. From our determinations a low value of free Mg2+ (less than 1 mM) is established for all of the tissues studied, including perfused heart muscle, contrary to a recent report in the literature. Saturating human erythrocytes with Mg2+ results in an alpha- and beta-phosphorus resonance separation for intracellular ATP that is indistinguishable from that observed in a noncellular MgATP control under similar conditions, showing that MgATP resonances in this cell are unaffected by the cellular environment.

  15. 1H-NMR measurements of proton mobility in nano-crystalline YSZ.

    PubMed

    Hinterberg, Judith; Adams, Alina; Blümich, Bernhard; Heitjans, Paul; Kim, Sangtae; Munir, Zuhair A; Martin, Manfred

    2013-12-01

    We report nuclear magnetic resonance (NMR) results on water saturated, dense, nano-crystalline YSZ samples (9.5 mol% yttria doped zirconia) which exhibit proton conductivity at temperatures as low as room temperature. (1)H-NMR spectra recorded under static and magic angle spinning conditions show two distinct signals. Their temperature-dependent behavior and their linewidths suggest that one can be attributed to (free) water adsorbed on the surface of the sample and the other one to mobile protons within the sample. This interpretation is supported by comparison with measurements on a single-crystalline sample. For the nano-crystalline samples motional narrowing is observed for the signal originating from protons in the sample interior. For these protons, the analysis of temperature and field dependent spin-lattice relaxation time T1 points towards diffusion in a confined two-dimensional geometry. We attribute this quasi two-dimensional motion to protons that are mobile along internal interfaces or nanopores of nano-crystalline YSZ.

  16. Electrophoretic study of Clostridium species.

    PubMed Central

    Cato, E P; Hash, D E; Holdeman, L V; Moore, W E

    1982-01-01

    Polyacrylamide gel electrophoretic analysis of soluble cellular proteins (without sodium dodecyl sulfate) of 70 Clostridium species indicated that the procedure was readily applicable to the differentiation of species in the genus. The protein patterns correlated well with the available DNA homology data and with most accepted differential tests. Results indicated that several earlier names for species were synonyms of those of accepted species and that two accepted species may be synonymous. Images PMID:6175658

  17. 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.

  18. 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

  19. Measuring Residual Dipolar Couplings in Excited Conformational States of Nucleic Acids by CEST NMR Spectroscopy.

    PubMed

    Zhao, Bo; Zhang, Qi

    2015-10-28

    Nucleic acids undergo structural transitions to access sparsely populated and transiently lived conformational states--or excited conformational states--that play important roles in diverse biological processes. Despite ever-increasing detection of these functionally essential states, 3D structure determination of excited states (ESs) of RNA remains elusive. This is largely due to challenges in obtaining high-resolution structural constraints in these ESs by conventional structural biology approaches. Here, we present nucleic-acid-optimized chemical exchange saturation transfer (CEST) NMR spectroscopy for measuring residual dipolar couplings (RDCs), which provide unique long-range angular constraints in ESs of nucleic acids. We demonstrate these approaches on a fluoride riboswitch, where one-bond (13)C-(1)H RDCs from both base and sugar moieties provide direct structural probes into an ES of the ligand-free riboswitch.

  20. Direct measurement of brain glucose concentrations in humans by sup 13 C NMR spectroscopy

    SciTech Connect

    Gruetter, R.; Novotny, E.J.; Boulware, S.D.; Rothman, D.L.; Mason, G.F.; Shulman, G.I.; Shulan, R.G.; Tamborlane, W.V. )

    1992-02-01

    Glucose is the main fuel for energy metabolism in the normal human brain. It is generally assumed that glucose transport into the brain is not rate-limiting for metabolism. Since brain glucose concentrations cannot be determined directly by radiotracer techniques, the authors used {sup 13}C NMR spectroscopy after infusing enriched D-(1-{sup 13}C)glucose to measure brain glucose concentrations at euglycemia and at hyperglycemia in six healthy children. Brain glucose concentrations averaged 1.0 {plus minus} 0.1 {mu}mol/ml at euglycemia and 1.8-2.7 {mu}mol/ml at hyperglycemia. Michaelis-Menten parameters of transport were calculated from the relationship between plasma and brain glucose concentrations. The brain glucose concentrations and transport constants are consistent with transport not being rate-limiting for resting brain metabolism at plasma levels >3 mM.

  1. 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.

  2. 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.

  3. Binding of phenol and differently halogenated phenols to dissolved humic matter as measured by NMR spectroscopy.

    PubMed

    Smejkalová, Daniela; Spaccini, Riccardo; Fontaine, Barbara; Piccolo, Alessandro

    2009-07-15

    1H- and 19F-NMR measurements of spin-lattice (T1) and spin-spin (T2) relaxationtimes and diffusion ordered spectroscopy (DOSY) were applied to investigate the association of nonsubstituted (phenol (P)) and halogen-substituted (2,4-dichlorophenol (DCP); 2,4,6-trichlorophenol (TCP), and 2,4,6-trifluorophenol (TFP) phenols with a dissolved humic acid (HA). T1 and T2 values for both 1H and 19F in phenols decreased with enhancing HA concentration, indicating reduction in molecular mobility due to formation of noncovalent interactions. Moreover, correlation times (tau c) for different hydrogen and fluorine atoms in phenols showed that anisotropic mobility turned into isotropic motion with HA additions. Changes in relaxation times suggested that DCP and TCP were more extensively bound to HA than P and TFP. This was confirmed by diffusion measurements which showed full association of DCP and TCP to a less amount of HA than that required for entire complexation of P and TFP. Calculated values of binding constants (Ka) reflected the overall NMR behavior, being significantly larger for DCP- and TCP-HA (10.04 +/- 1.32 and 4.47 +/- 0.35 M(-1), respectively) than for P- and TFP-HA complexes (0.57 +/- 0.03 and 0.28 +/- 0.01 M(-1), respectively). Binding increased with decreasing solution pH, thus indicating a dependence on the fraction of protonated form (alpha) of phenols in solution. However, it was found that the hydrophobicity conferred to phenols by chlorine atoms on aromatic rings is a stronger drive than alpha for the phenols repartition within the HA hydrophobic domains.

  4. 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.

  5. Ultrafast NMR T1 Relaxation Measurements: Probing Molecular Properties in Real Time

    PubMed Central

    Smith, Pieter E. S.; Donovan, Kevin J.; Szekely, Or; Baias, Maria; Frydman, Lucio

    2016-01-01

    The longitudinal relaxation properties of NMR active nuclei carry useful information about the site-specific chemical environments and about the mobility of molecular fragments. Molecular mobility is in turn a key parameter reporting both on stable properties like size, as well as on dynamic ones such as transient interactions and irreversible aggregation. In order to fully investigate the latter, a fast sampling of the relaxation parameters of transiently formed molecular species may be needed. Nevertheless, the acquisition of longitudinal relaxation data is typically slow, being limited by the requirement that the time for which the nucleus relaxes be varied incrementally until a complete build-up curve is generated. Recently a number of single-shot inversion recovery methods have been developed capable of alleviating this need; still, these may be challenged by either spectral resolution restrictions or when coping with very fast relaxing nuclei. Here we present a new experiment to measure the T1s of multiple nuclear spins that experience fast longitudinal relaxation, while retaining full high-resolution chemical shift information. Good agreement is observed between T1s measured with conventional means and T1s measured using the new technique. The method is applied to the real time investigation of the reaction between D-xylose and sodium borate, which is in turn elucidated with the aid of ancillary ultrafast and conventional 2D TOCSY measurements. PMID:23878001

  6. 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…

  7. 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.

  8. 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

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

    PubMed

    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 (15)N-labeled SH3 (Src homology 3) domain proteins in aqueous buffer were used to generate general order parameters (S(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(2)) were derived from the MD trajectory. Correlation analysis using the Gromos force field indicated that S(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(2) parameters from MD simulations with charges for all three histidines and with the SPC/E water model correlated well with S(2) calculated from the experimental NMR relaxation measurements, in a site-specific manner.

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. Electrophoretic deposition of porous hydroxyapatite scaffold.

    PubMed

    Ma, J; Wang, C; Peng, K W

    2003-09-01

    Bioactive porous hydroxyapatite (HA) scaffold was fabricated using electrophoretic deposition (EPD) technique in the present work. Bulk HA scaffold was achieved by repeated deposition. The green scaffold was sintered at 1200 degrees C to 82% of the theoretical density. Scanning electron microscopy examination and mercury porosimetry measurement have shown that the porosity remains interconnected and a range of pore size from several microns to hundreds of microns was obtained. X-ray diffraction analysis was performed and confirmed that there is no HA decomposition during the sintering process. Mechanical characterization has also shown that the EPD scaffold possesses excellent properties. Cell culturing experiment was carried out and the result shows that the scaffold bioactivity is not only dependent on the interconnectivity of the pores, but also the pore size.

  15. 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.'

  16. 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.

  17. Diffusion anisotropy in excised normal rat spinal cord measured by NMR microscopy.

    PubMed

    Inglis, B A; Yang, L; Wirth, E D; Plant, D; Mareci, T H

    1997-01-01

    A conventional spin-echo NMR imaging pulse sequence was used to obtain high-resolution images of excised normal rat spinal cord at 7 and 14 T. It was observed that the large pulsed-field gradients necessary for high-resolution imaging caused a diffusion weighting that dominated the image contrast and that could be used to infer microscopic structural organization beyond that defined by the resolution of the image matrix (i.e., fiber orientation could be assigned based on diffusion anisotropy). Anisotropic diffusion coefficients were therefore measured using apparent diffusion tensor (ADT) imaging to assess more accurately fiber orientations in the spinal cord; structural anisotropy information is portrayed in the six unique images of the complete ADT. To reduce the dimensionality of the data, a trace image was generated using a separate color scale for each of the three diagonal element images of the ADT. This new image retains much of the invariance of the trace to the relative orientations of laboratory and sample axes (inherent to a greyscale trace image) but provides, by the use of color, contrast reflecting diffusion anisotropy. The colored trace image yields a pseudo-three-dimensional view of the rat spinal cord, from which it is possible to deduce fiber orientations.

  18. Diffusion of small solutes in cartilage as measured by nuclear magnetic resonance (NMR) spectroscopy and imaging.

    PubMed

    Burstein, D; Gray, M L; Hartman, A L; Gipe, R; Foy, B D

    1993-07-01

    The ability of water and solutes to move through the cartilage matrix is important to the normal function of cartilage and is presumed to be altered in degenerative diseases of cartilage such as osteoarthritis and rheumatoid arthritis. Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) techniques were used to measure a self diffusion coefficient (D) for small solutes in samples of explanted cartilage for diffusion times ranging from 13 ms to 2 s. With a diffusion time of 13 ms, the intratissue diffusivity of several small solutes (water, Na+, Li+, and CF3CO2-) was found consistently to be about 60% of the diffusivity of the same species in free solution. Equilibration of the samples at low pH (which titrates the charge groups so that the net matrix charge of -300 mM at pH 8 becomes approximately -50 mM at pH 2) did not affect the diffusivity of water or Na+. These data, and the similarity between the D in cartilage relative to free solution for water, anions, and cations, are consistent with the view that charge is not an important determinant of the intratissue diffusivity of small solutes in cartilage. With 35% compression, the diffusivity of water and Li+ dropped by 19 and 39%, respectively. In contrast, the diffusivity of water increased by 20% after treatment with trypsin (to remove the proteoglycans and noncollagenous proteins). These data and the lack of an effect of charge on diffusivity are consistent with D being dependent on the composition and density of the solid tissue matrix. A series of diffusion-weighted proton images demonstrated that D could be measured on a localized basis and that changes in D associated with an enzymatically depleted matrix could be clearly observed. Finally, evidence of restriction to diffusion within the tissue was found with studies in which D was measured as a function of diffusion time. The measured D for water in cartilage decreased with diffusion times ranging from 25 ms to 2 s, at which

  19. Electrophoretic karyotype of Cercospora kikuchii.

    PubMed

    Hightower, R C; Callahan, T M; Upchurch, R G

    1995-02-01

    Classical genetic analyses are not possible with the phytopathogenic fungus Cercospora kikuchii since no sexual stage has been identified. To facilitate gene mapping and to develop an understanding of the genome organization of C. kikuchii, an electrophoretic karyotype has been obtained using contour-clamped homogeneous electric field gel electrophoresis (CHEF). Eight chromosomes, two of which migrate as a doublet, have been separated into seven bands ranging from 2.0 to 5.5 Mb. Using this determination of chromosome number and size, the total genome size of C. kikuchii is estimated to be 28.4 Mb. In addition, genes encoding tubulin, ribosomal DNA, and four previously isolated light-enhanced cDNAs from C. kikuchii were assigned to chromosomes by Southern-hybridization analysis of CHEF blots.

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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

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

    PubMed

    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 >1GHz. 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 400MHz 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 400MHz 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. PMID:26778351

  8. 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.

  9. 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.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    Saalwächter, Kay

    2014-08-01

    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.

  12. 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

  13. 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

  14. Electrophoretic cell separation by means of immunomicrospheres

    NASA Technical Reports Server (NTRS)

    Rembaum, A.; Smolka, A. J. K.

    1980-01-01

    The electrophoretic mobility of fixed human red blood cells immunologically labeled with polymeric (4-vinyl)pyridine or polyglutaraldehyde microspheres was altered to a considerable extent. This observation was utilized in the preparative scale electrophoretic separation of human and turkey fixed red blood cells, whose mobilities under normal physiological conditions do not differ sufficiently to allow their separation by continuous flow electrophoresis. It is suggested that resolution in the electrophoretic separation of cell subpopulations, currently limited by finite and often overlapping mobility distributions, may be significantly enhanced by immuno-specific labeling of target populations using microspheres.

  15. On the role of experimental imperfections in constructing (1)H spin diffusion NMR plots for domain size measurements.

    PubMed

    Nieuwendaal, Ryan C

    2016-01-01

    We discuss the precision of 1D chemical-shift-based (1)H spin diffusion NMR experiments as well as straightforward experimental protocols for reducing errors. The (1)H spin diffusion NMR experiments described herein are useful for samples that contain components with significant spectral overlap in the (1)H NMR spectrum and also for samples of small mass (<1mg). We show that even in samples that display little spectral contrast, domain sizes can be determined to a relatively high degree of certainty if common experimental variability is accounted for and known. In particular, one should (1) measure flip angles to high precision (≈±1° flip angle), (2) establish a metric for phase transients to ensure their repeatability, (3) establish a reliable spectral deconvolution procedure to ascertain the deconvolved spectra of the neat components in the composite or blend spin diffusion spectrum, and (4) when possible, perform 1D chemical-shift-based (1)H spin diffusion experiments with zero total integral to partially correct for errors and uncertainties if these requirements cannot fully be implemented. We show that minimizing the degree of phase transients is not a requirement for reliable domain size measurement, but their repeatability is essential, as is knowing their contribution to the spectral offset (i.e. the J1 coefficient). When performing experiments with zero total integral in the spin diffusion NMR spectrum with carefully measured flip angles and known phase transient effects, the largest contribution to error arises from an uncertainty in the component lineshapes which can be as high as 7%. This uncertainty can be reduced considerably if the component lineshapes deconvolved from the composite or blend spin diffusion spectra adequately match previously acquired pure component spectra. PMID:27039203

  16. 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.

  17. Electrophoretic control of actomyosin motility

    NASA Astrophysics Data System (ADS)

    Hanson, Kristi L.; Solana, Gerardin; Nicolau, Dan V.

    2005-03-01

    The effect of DC electric field strength on in vitro actomyosin motility was examined. Rabbit skeletal muscle heavy meromyosin (HMM) was adsorbed to nitrocellulose-coated glass, and the myosin driven movement of fluorescently labeled actin filaments was recorded in the presence of 0 to 9000 V m-1 applied DC voltage. The applied electric field resulted in increased filament velocity and oriented actin movement, with leading heads of filaments directed towards the positive electrode. Velocity (v) was found to increase moderately with electric field strength at applied fields up to ~ 4500 V m-1 (Δv/ΔE = 0.037 μm2 V-1sec-1), and then increased at a more rapid rate (Δv/ΔE = 0.100 μm2 V-1sec-1) at higher field strengths up to 9000 V m-1. The electrophoretic effect caused up to 70% of actin motion to be oriented within 30 degrees of the positive electrode, with the largest effect observed using an applied field of 6000 V m-1. Higher electric field strengths caused filament breakage.

  18. 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.

  19. 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.

  20. 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.

  1. 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

    2016-03-04

    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.

  2. 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

  3. Rapid measurement of multidimensional 1H solid-state NMR spectra at ultra-fast MAS frequencies

    NASA Astrophysics Data System (ADS)

    Ye, Yue Qi; Malon, Michal; Martineau, Charlotte; Taulelle, Francis; Nishiyama, Yusuke

    2014-02-01

    A novel method to realize rapid repetition of 1H NMR experiments at ultra-fast MAS frequencies is demonstrated. The ultra-fast MAS at 110 kHz slows the 1H-1H spin diffusion, leading to variations of 1H T1 relaxation times from atom to atom within a molecule. The different relaxation behavior is averaged by applying 1H-1H recoupling during relaxation delay even at ultra-fast MAS, reducing the optimal relaxation delay to maximize the signal to noise ratio. The way to determine optimal relaxation delay for arbitrary relaxation curve is shown. The reduction of optimal relaxation delay by radio-frequency driven recoupling (RFDR) was demonstrated on powder samples of glycine and ethenzamide with one and multi-dimensional NMR measurements.

  4. 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...

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

    DOE PAGES

    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

  6. 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.

  7. (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

  8. Gas-phase NMR measurements, absolute shielding scales, and magnetic dipole moments of 29Si and 73Ge nuclei.

    PubMed

    Makulski, W; Jackowski, K; Antusek, A; Jaszuński, M

    2006-10-12

    New gas-phase NMR measurements of the shielding constants of 29Si, 73Ge, and 1H nuclei in SiH4 and GeH4 are reported. The results, extrapolated to zero density, provide accurate isolated molecule values, best suited for comparison with theoretical calculations. Using the recent ab initio results for these molecules and the measured chemical shifts, we determine the absolute shielding scales for 29Si and 73Ge. This allows us to provide new values of the nuclear magnetic dipole moments for these two nuclei; in addition, we examine the dipole moments of 13C and 119Sn.

  9. Biogenic phosphorus in oligotrophic mountain lake sediments: differences in composition measured with NMR spectroscopy.

    PubMed

    Ahlgren, Joakim; Reitzel, Kasper; Danielsson, Rolf; Gogoll, Adolf; Rydin, Emil

    2006-12-01

    Phosphorus (P) composition in alkaline sediment extracts from three Swedish oligotrophic mountain lakes was investigated using 31P-NMR spectroscopy. Surface sediments from one natural lake and two mature reservoirs, one of which has received nutrient additions over the last 3 years, were compared with respect to biogenic P composition. The results show significant differences in the occurrence of labile and biogenic P species in the sediments of the different systems. The P compound groups that varied most between these three systems were pyrophosphate and polyphosphates, compound groups known to play an important role in sediment P recycling. The content of these compound groups was lowest in the reservoirs and may indicate a coupling between anthropogenic disturbances (i.e., impoundment) to a water system and the availability of labile P species in the sediment. A statistical study was also conducted to determine the accuracy and reliability of using 31P-NMR spectroscopy for quantification of sediment P forms. PMID:17070896

  10. Microsolvation and sp2-stereoinversion of monomeric α-(2,6-di-tert-butylphenyl)vinyllithium as measured by NMR

    PubMed Central

    Knittl, Monika; Rossmann, Eva C

    2014-01-01

    Summary The β-unsubstituted title compound dissolves in THF as a uniformly trisolvated monomer, whereas it forms exclusively disolvated monomers in tert-butyl methyl ether, Et2O, TMEDA, or toluene with TMEDA (1.4 equiv). This was established at low temperatures through the observation of separated NMR signals for free and lithium-coordinated ligands and/or through the patterns and magnitudes of 13C,6Li NMR coupling constants. An aggregated form was observed only with Et2O (2 equiv) in toluene as the solvent. The olefinic geminal interproton coupling constants of the H2C= part can be used as a secondary criterion to differentiate between these differently solvated ground-states (3, 2, or <2 coordinated ligands per Li). Due to a kinetic trisolvation privilege of THF, the cis/trans sp2-stereoinversion rates could be measured through analyses of 1H NMR line broadening and coalescence only in THF as the solvent: The pseudomonomolecular (because THF-catalyzed), ionic mechanism is initialized by a C–Li bond heterolysis with the transient immobilization of one additional THF ligand, followed by stereoinversion of the quasi-sp2-hybridized carbanionic center in cooperation with a “conducted tour” migration of Li+(THF)4 along the α-aryl group within the solvent-separated ion pair. PMID:25383123

  11. 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.

  12. Demonstration of cell-ricin interaction by electrophoretic light scattering.

    PubMed

    Hakim Hachemi, B; Betrencourt, C; Volochine, B; Frénoy, J P; Chraïbi, Z; Alfsen, A; Lavialle, F

    1989-07-01

    Electrophoretic light scattering has been used to investigate the interaction of ricin, a vegetal toxin, with cells. This technique allowed measurements in the presence of free ligand and proved particularly useful for the study of a system with low affinity. The electrophoretic mobility of erythrocytes and oligodendrocytes was found equal to 2.08 x 10(-8) and 2.35 x 10(-8)m2s-1V-1, respectively. Upon ricin binding, these values decreased significantly. This change was related to the saturation of the binding sites. The specificity of the interaction was demonstrated by conducting the experiments in the presence of lactose. This specific inhibitor fully prevented the ricin-cell interaction.

  13. 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.

  14. 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

  15. 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

    Bono, 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

  16. 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

  17. 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

  18. 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.

  19. Cation location in microporous zeolite, SSZ-13, probed with xenon adsorption measurement and 129Xe NMR spectrum.

    PubMed

    Shin, Na Ra; Kim, Su Hyun; Shin, Hye Sun; Jang, Ik Jun; Cho, Sung June

    2013-06-01

    The location of metal ion, Ag2+, Ca2+, Cu2+ and Y3+ in the SSZ-13 has been investigated with xenon adsorption measurement and 129Xe NMR spectrum. It was referred that the location of the metal ion varies depending on the corresponding charge. The ion-exchanged Ag ion was located in the alpha-cage to interact directly with xenon. Others multivalent cation contributed little with xenon because these were present near the six membered rings where xenon cannot access. PMID:23862500

  20. 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.

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

    SciTech Connect

    Koretsky, A.P.

    1984-08-01

    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. Chronically implanted detection coils, employing a balanced matching configuration of capacitors in the tuned circuit, were used to obtain /sup 31/P NMR spectra from heart, kidney, and liver in situ. Gated spectra of heart obtained at systole and diastole and the effects of fructose on kidney and liver were studied. The ability to observe other nuclei using implanted coils is illustrated with /sup 39/K NMR spectra from kidney and muscle. 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 (13 ..mu..mol/min/gm tissue) were compared to whole kidney oxygen consumption and Na/sup +/ reabsorption rates to derive ATP/O (0.8 to 1.7) and Na/sup +//ATP (4 to 10) 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.

  2. Sediment depth attenuation of biogenic phosphorus compounds measured by 31P NMR.

    PubMed

    Ahlgren, Joakim; Tranvik, Lars; Gogoll, Adolf; Waldeback, Monica; Markides, Karin; Rydin, Emil

    2005-02-01

    Being a major cause of eutrophication and subsequent loss of water quality, the turnover of phosphorus (P) in lake sediments is in need of deeper understanding. A major part of the flux of P to eutrophic lake sediments is organically bound or of biogenic origin. This P is incorporated in a poorly described mixture of autochthonous and allochthonous sediment and forms the primary storage of P available for recycling to the water column, thus regulating lake trophic status. To identify and quantify biogenic sediment P and assess its lability, we analyzed sediment cores from Lake Erken, Sweden, using traditional P fractionation, and in parallel, NaOH extracts were analyzed using 31P NMR. The surface sediments contain orthophosphates (ortho-P) and pyrophosphates (pyro-P), as well as phosphate mono- and diesters. The first group of compounds to disappear with increased sediment depth is pyrophosphate, followed by a steady decline of the different ester compounds. Estimated half-life times of these compound groups are about 10 yr for pyrophosphate and 2 decades for mono- and diesters. Probably, these compounds will be mineralized to ortho-P and is thus potentially available for recycling to the water column, supporting further growth of phytoplankton. In conclusion, 31P NMR is a useful tool to asses the bioavailability of certain P compound groups, and the combination with traditional fractionation techniques makes quantification possible. PMID:15757351

  3. sup 31 P NMR measurements of the ADP concentration in yeast cells genetically modified to express creatine kinase

    SciTech Connect

    Brindle, K.; Braddock, P.; Fulton, S. )

    1990-04-03

    Rabbit muscle creatine kinase has been introduced into the yeast Saccharomyces cerevisiae by transforming cells with a multicopy plasmid containing the coding sequence for the enzyme under the control of the yeast phosphoglycerate kinase promoter. The transformed cells showed creating kinase activities similar to those found in mammalian heart muscle. {sup 31}P NMR measurements of the near-equilibrium concentrations of phosphocreatine and cellular pH together with measurements of the total extractable concentrations of phosphocreatine and creatine allowed calculation of the free ADP/ATP ratio in the cell. The calculated ratio of approximately 2 was considerably higher than the ratio of between 0.06 and 0.1 measured directly in cell extracts.

  4. Electrophoretic karyotypes of some related Mucor species.

    PubMed

    Nagy, A; Palagyi, Z; Vastag, M; Ferenczy, L; Vágvölgyi, C

    2000-07-01

    Contour clamped homogeneous electric field (CHEF) gel electrophoresis was used to obtain electrophoretic karyotypes from nine Mucor strains representing five different species (M. bainieri, M. circinelloides, M. mucedo, M. plumbeus and M. racemosus). The chromosomal banding patterns revealed high variability among the isolates. The sizes of the DNA in the Mucor chromosomes were estimated to be between 2.5 and 8.7 Mb. The total genome sizes were calculated to be between 30.0 and 44.7 Mb. The applicability of these electrophoretic karyotypes for the investigation of genome structure, for strain identification and for species delimitation is considered.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Structure and equilibria of Ca 2+-complexes of glucose and sorbitol from multinuclear ( 1H, 13C and 43Ca) NMR measurements supplemented with molecular modelling calculations

    NASA Astrophysics Data System (ADS)

    Pallagi, A.; Dudás, Cs.; Csendes, Z.; Forgó, P.; Pálinkó, I.; Sipos, P.

    2011-05-01

    Ca 2+-complexation of D-glucose and D-sorbitol have been investigated with the aid of multinuclear ( 1H, 13C and 43Ca) NMR spectroscopy and ab initio quantum chemical calculations. Formation constants of the forming 1:1 complexes have been estimated from one-dimensional 13C NMR spectra obtained at constant ionic strength (1 M NaCl). Binding sites were identified from 2D 1H- 43Ca NMR spectra. 2D NMR measurements and ab initio calculations indicated that Ca 2+ ions were bound in a tridentate manner via the glycosidic OH, the ethereal oxygen in the ring and the OH on the terminal carbon for the α- and β-anomers of glucose and for sorbitol simultaneous binding of four hydroxide moieties (C1, C2, C4 and C6) was suggested.

  11. High-resolution magic angle spinning (1) H NMR measurement of ligand concentration in solvent-saturated chromatographic beads.

    PubMed

    Elwinger, Fredrik; Furó, István

    2016-04-01

    A method based on (1) H high-resolution magic angle spinning NMR has been developed for measuring concentration accurately in heterogeneous materials like that of ligands in chromatography media. Ligand concentration is obtained by relating the peak integrals for a butyl ligand in the spectrum of a water-saturated chromatography medium to the integral of the added internal reference. The method is fast, with capacity of 10 min total sample preparation and analysis time per sample; precise, with a reproducibility expressed as 1.7% relative standard deviation; and accurate, as indicated by the excellent agreement of derived concentration with that obtained previously by (13) C single-pulse excitation MAS NMR. The effects of radiofrequency field inhomogeneity, spin rate, temperature increase due to spinning, and distribution and re-distribution of medium and reference solvent both inside the rotor during spinning and between bulk solvent and pore space are discussed in detail. © 2016 The Authors Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd.

  12. 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.

  13. 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.

  14. Measuring the longitudinal NMR relaxation rates of fast relaxing nuclei using a signal eliminating relaxation filter.

    PubMed

    Hansen, D F; Led, J 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 degrees inversion pulse of this experiment with a signal eliminating relaxation filter (SERF) consisting of three 180 degrees pulses separated by two variable delays, Delta1 and Delta2. 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.

  15. Transport properties of bulk hydrogen and hydrogen-helium slush at 4MHz using NMR measurements.

    NASA Astrophysics Data System (ADS)

    Hamida, J. A.; Sullivan, N. S.

    2004-03-01

    The most promising large-scale advance in rocket propulsion is the use of atomic propellants, stabilized in cryogenic environments. The high energy atomic propellants must be stored in a stabilizing medium to inhibit or delay their combination into molecules. We report studies of a suitable cryogenic matrix for atomic propellants consisting of a slush of small grains of solid hydrogen floating in liquid helium. Using NMR techniques, transport properties for bulk samples of solid hydrogen at 4 MHz have been studied as a function of ortho concentration and temperature. In an earlier experiment we determined the stability, transport and thermal properties of a solid hydrogen-liquid helium stabilizer. The nuclear spin-spin and spin-lattice relaxation times of the stabilizer were observed to be appreciably shorter than that expected for bulk samples. We anticipate that the solid-liquid surface relaxation could be the critical path for relaxation towards equilibrium. To address this question, data on relaxation processes for hydrogen -helium slush prepared by different methods will be compared.

  16. Unraveling the complexity of protein backbone dynamics with combined (13)C and (15)N solid-state NMR relaxation measurements.

    PubMed

    Lamley, Jonathan M; Lougher, Matthew J; Sass, Hans Juergen; Rogowski, Marco; Grzesiek, Stephan; Lewandowski, Józef R

    2015-09-14

    Typically, protein dynamics involve a complex hierarchy of motions occurring on different time scales between conformations separated by a range of different energy barriers. NMR relaxation can in principle provide a site-specific picture of both the time scales and amplitudes of these motions, but independent relaxation rates sensitive to fluctuations in different time scale ranges are required to obtain a faithful representation of the underlying dynamic complexity. This is especially pertinent for relaxation measurements in the solid state, which report on dynamics in a broader window of time scales by more than 3 orders of magnitudes compared to solution NMR relaxation. To aid in unraveling the intricacies of biomolecular dynamics we introduce (13)C spin-lattice relaxation in the rotating frame (R1ρ) as a probe of backbone nanosecond-microsecond motions in proteins in the solid state. We present measurements of (13)C'R1ρ rates in fully protonated crystalline protein GB1 at 600 and 850 MHz (1)H Larmor frequencies and compare them to (13)C'R1, (15)N R1 and R1ρ measured under the same conditions. The addition of carbon relaxation data to the model free analysis of nitrogen relaxation data leads to greatly improved characterization of time scales of protein backbone motions, minimizing the occurrence of fitting artifacts that may be present when (15)N data is used alone. We also discuss how internal motions characterized by different time scales contribute to (15)N and (13)C relaxation rates in the solid state and solution state, leading to fundamental differences between them, as well as phenomena such as underestimation of picosecond-range motions in the solid state and nanosecond-range motions in solution.

  17. 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.

  18. 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

  19. NMR evidence of a sharp change in a measure of local order in deeply supercooled confined water

    PubMed Central

    Mallamace, F.; Corsaro, C.; Broccio, M.; Branca, C.; González-Segredo, N.; Spooren, J.; Chen, S.-H.; Stanley, H. E.

    2008-01-01

    Using NMR, we measure the proton chemical shift δ, of supercooled nanoconfined water in the temperature range 195 K < T < 350 K. Because δ is directly connected to the magnetic shielding tensor, we discuss the data in terms of the local hydrogen bond geometry and order. We argue that the derivative −(∂ ln δ/∂T)P should behave roughly as the constant pressure specific heat CP(T), and we confirm this argument by detailed comparisons with literature values of CP(T) in the range 290–370 K. We find that −(∂ ln δ/∂T)P displays a pronounced maximum upon crossing the locus of maximum correlation length at ≈240 K, consistent with the liquid-liquid critical point hypothesis for water, which predicts that CP(T) displays a maximum on crossing the Widom line. PMID:18753633

  20. 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.

  1. 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.

  2. Reversible unfolding of cytochrome c upon interaction with cardiolipin bilayers. 2. Evidence from phosphorus-31 NMR measurements

    SciTech Connect

    Spooner, P.J.R.; Watts, A. )

    1991-04-23

    {sup 31}P NMR measurements were conducted to determine the structural and chemical environment of beef heart cardiolipin when bound to cytochrome c. {sup 31}P NMR line shapes infer that the majority of lipid remains in the bilayer state and that the average conformation of the lipid phosphate is not greatly affected by binding to the protein. An analysis of the spin-lattice (T{sub 1}) relaxation times of hydrated cardiolipin as a function of temperature describes a T{sub 1} minimum at around 25{degree}C which leads to a correlation time for the phosphates in the lipid headgroup of 0.71 ns. The relaxation behavior of the protein-lipid complex was markedly different, showing a pronounced enhancement in the phosphorus spin-lattice relaxation rate. This effect of the protein increased progressively with increasing temperature, giving no indication of a minimum in T{sub 1} up to 75{degree}C. The enhancement in lipid phosphorus T{sub 1} relaxation was observed with protein in both oxidation states, being somewhat less marked for the reduced form. The characteristics of the T{sub 1} effects and the influence of the protein on other relaxation processes determined for the lipid phosphorus (spin-spin relaxation and longitudinal relaxation in the rotating frame) point to a strong paramagnetic interaction from the protein. A comparison with the relaxation behavior of samples spinning at the magic angle was also consistent with this mechanism. The results suggest that cytochrome c reversibly denatures on complexation with cardiolipin bilayers, such that the electronic ground state prevailing in the native structure of both oxidized and reduced protein can convert to high-spin states with greater magnetic susceptibility.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. The Inversion of NMR Log Data Sets with Different Measurement Errors

    NASA Astrophysics Data System (ADS)

    Dunn, Keh-Jim; LaTorraca, Gerald A.

    1999-09-01

    We present a composite-data processing method which simultaneously processes two or more data sets with different measurement errors. We examine the role of the noise level of the data in the singular value decomposition inversion process, the criteria for a proper cutoff, and its effect on the uncertainty of the solution. Examples of processed logs using the composite-data processing method are presented and discussed. The possible usefulness of the apparent T1/T2 ratio extracted from the logs is illustrated.

  10. The inversion of NMR log data sets with different measurement errors.

    PubMed

    Dunn, K J; LaTorraca, G A

    1999-09-01

    We present a composite-data processing method which simultaneously processes two or more data sets with different measurement errors. We examine the role of the noise level of the data in the singular value decomposition inversion process, the criteria for a proper cutoff, and its effect on the uncertainty of the solution. Examples of processed logs using the composite-data processing method are presented and discussed. The possible usefulness of the apparent T(1)/T(2) ratio extracted from the logs is illustrated. PMID:10479558

  11. 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.

  12. 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.

  13. Rapid measurement of pseudocontact shifts in metalloproteins by proton-detected solid-state NMR spectroscopy.

    PubMed

    Knight, Michael J; Felli, Isabella C; Pierattelli, Roberta; Bertini, Ivano; Emsley, Lyndon; Herrmann, Torsten; Pintacuda, Guido

    2012-09-12

    Pseudocontact shifts (PCSs) arise in paramagnetic systems in which the susceptibility tensor is anisotropic. PCSs depend upon the distance from the paramagnetic center and the position relative to the susceptibility tensor, and they can be used as structural restraints in protein structure determination. We show that the use of (1)H-detected solid-state correlations provides facile and rapid detection and assignment of site-specific PCSs, including resolved (1)H PCSs, in a large metalloprotein, Co(2+)-substituted superoxide dismutase (Co(2+)-SOD). With only 3 mg of sample and a small set of experiments, several hundred PCSs were measured and assigned, and these PCSs were subsequently used in combination with (1)H-(1)H distance and dihedral angle restraints to determine the protein backbone geometry with a precision paralleling those of state-of-the-art liquid-state determinations of diamagnetic proteins, including a well-defined active site.

  14. 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.

  15. Investigation into the structural composition of hydroalcoholic solutions as basis for the development of multiple suppression pulse sequences for NMR measurement of alcoholic beverages.

    PubMed

    Monakhova, Yulia B; Mushtakova, Svetlana P; Kuballa, Thomas; Lachenmeier, Dirk W

    2014-12-01

    An eight-fold suppression pulse sequence was recently developed to improve sensitivity in (1) H NMR measurements of alcoholic beverages [Magn. Res. Chem. 2011 (49): 734-739]. To ensure that only one combined hydroxyl peak from water and ethanol appears in the spectrum, adjustment to a certain range of ethanol concentrations was required. To explain this observation, the structure of water-ethanol solutions was studied. Hydroalcoholic solutions showed extreme behavior at 25% vol, 46% vol, and 83% vol ethanol according to (1) H NMR experiments. Near-infrared spectroscopy confirmed the occurrence of four significant compounds ('individual' ethanol and water structures as well as two water-ethanol complexes of defined composition - 1 : 1 and 1 : 3). The successful multiple suppression can be achieved for every kind of alcoholic beverage with different alcoholic strengths, when the final ethanol concentration is adjusted to a range between 25% vol and 46% vol (e.g. using dilution or pure ethanol addition). In this optimum region, an individual ethanol peak was not detected, because the 'individual' water structure and the 1 : 1 ethanol-water complex predominate. The nature of molecular association in ethanol-water solutions is essential to elucidate NMR method development for measurement of alcoholic beverages. The presented approach can be used to optimize other NMR suppression protocols for binary water-organic solvent mixtures, where hydrogen bonding plays a dominant role.

  16. Development of an eight-channel NMR system using RF detection coils for measuring spatial distributions of current density and water content in the PEM of a PEFC.

    PubMed

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

    2013-09-01

    The water generation and water transport occurring in a polymer electrolyte fuel cell (PEFC) can be estimated from the current density generated in the PEFC, and the water content in the polymer electrolyte membrane (PEM). In order to measure the spatial distributions and time-dependent changes of current density generated in a PEFC and the water content in a PEM, we have developed an eight-channel nuclear magnetic resonance (NMR) system. To detect a NMR signal from water in a PEM at eight positions, eight small planar RF detection coils of 0.6 mm inside diameter were inserted between the PEM and the gas diffusion layer (GDL) in a PEFC. The local current density generated at the position of the RF detection coil in a PEFC can be calculated from the frequency shift of the obtained NMR signal due to an additional magnetic field induced by the local current density. In addition, the water content in a PEM at the position of the RF detection coil can be calculated by the amplitude of the obtained NMR signal. The time-dependent changes in the spatial distributions were measured at 4 s intervals when the PEFC was operated with supply gas under conditions of fuel gas utilization of 0.67 and relative humidity of the fuel gas of 70%RH. The experimental result showed that the spatial distributions of the local current density and the water content in the PEM within the PEFC both fluctuated with time.

  17. Strategies for diagnosing and alleviating artifactual attenuation associated with large gradient pulses in PGSE NMR diffusion measurements.

    PubMed

    Price, W S; Hayamizu, K; Ide, H; Arata, Y

    1999-08-01

    The generation of phase-based artifacts resulting from mismatch in the effective areas (i.e., the time integrals) of sequential gradient pulses is discussed in the context of large gradient pulsed-gradient spin-echo (PGSE) NMR diffusion measurements. Such effects result in artifactual attenuation and distortion in the spectra which, in the first instance, are similar to (and commonly mistaken for) the effects of eddy currents. Small degrees of mismatch cause "unphysical" concave downward curvature in PGSE attenuation plots of freely diffusing species. However, larger mismatches can result in artifactual diffraction peaks in the plots which could easily be confused for true restricted diffusion effects. Although "rectangular" gradient pulses are preferable from a theoretical viewpoint, we found that shaped gradient (e.g., half-sine) pulses, which due to their slower rise and fall times were more tractable for the current amplifier, were more sequentially reproducible. As well as generating fewer phase-based artifacts such shaped pulses also decrease the likelihood of vibration problems.

  18. Direct measurement of the Mn(II) hydration state in metal complexes and metalloproteins through 17O NMR line widths.

    PubMed

    Gale, Eric M; Zhu, Jiang; Caravan, Peter

    2013-12-11

    Here we describe a simple method to estimate the inner-sphere hydration state of the Mn(II) ion in coordination complexes and metalloproteins. The line width of bulk H2(17)O is measured in the presence and absence of Mn(II) as a function of temperature, and transverse (17)O relaxivities are calculated. It is demonstrated that the maximum (17)O relaxivity is directly proportional to the number of inner-sphere water ligands (q). Using a combination of literature data and experimental data for 12 Mn(II) complexes, we show that this method provides accurate estimates of q with an uncertainty of ±0.2 water molecules. The method can be implemented on commercial NMR spectrometers working at fields of 7 T and higher. The hydration number can be obtained for micromolar Mn(II) concentrations. We show that the technique can be extended to metalloproteins or complex:protein interactions. For example, Mn(II) binds to the multimetal binding site A on human serum albumin with two inner-sphere water ligands that undergo rapid exchange (1.06 × 10(8) s(-1) at 37 °C). The possibility of extending this technique to other metal ions such as Gd(III) is discussed.

  19. A Method for Helical RNA Global Structure Determination in Solution Using Small Angle X-ray Scattering and NMR Measurements

    PubMed Central

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

    2009-01-01

    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 (SAXS) 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-nucleotide RNA using experimental data. The backbone root-mean-square-deviation (RMSD) of the ensemble of the calculated global structures relative to the X-ray crystal structure using the experimental data is 3.0 ± 0.3 Å, and the RMSD is only 2.5 ± 0.2 Å for the three duplexes that were orientation-restrained during the calculation. The global structure simplifies interpretation of multi-dimensional nuclear Overhauser spectra for high resolution structure determination. The potential general application of the method for RNA structure determination is discussed. PMID:19666030

  20. 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...

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. Measurement of State-Specific Association Constants in Allosteric Sensors through Molecular Stapling and NMR.

    PubMed

    Moleschi, Kody J; Akimoto, Madoka; Melacini, Giuseppe

    2015-08-26

    Allostery is a ubiquitous mechanism to control biological function and arises from the coupling of inhibitory and binding equilibria. The extent of coupling reflects the inactive vs active state selectivity of the allosteric effector. Hence, dissecting allosteric determinants requires quantification of state-specific association constants. However, observed association constants are typically population-averages, reporting on overall affinities but not on allosteric coupling. Here we propose a general method to measure state-specific association constants in allosteric sensors based on three key elements, i.e., state-selective molecular stapling through disulfide bridges, competition binding saturation transfer experiments and chemical shift correlation analyses to gauge state populations. The proposed approach was applied to the prototypical cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA-RIα), for which the structures of the inactive and active states are available, as needed to design the state-selective disulfide bridges. Surprisingly, the PKA-RIα state-specific association constants are comparable to those of a structurally homologous domain with ∼10(3)-fold lower cAMP-affinity, suggesting that the affinity difference arises primarily from changes in the position of the dynamic apo inhibitory equilibrium.

  6. Variation of electrophoretic karyotypes among clinical isolates of Candida albicans.

    PubMed Central

    Merz, W G; Connelly, C; Hieter, P

    1988-01-01

    Orthogonal-field-alternation gel electrophoresis was used to compare clinical isolates of Candida albicans by resolving chromosome-sized DNA molecules into an electrophoretic karyotype. Seven to nine bands were observed among isolates recovered from 17 patients. In addition, 14 distinct electrophoretic patterns were noted among the isolates from these patients. In a given individual, isolates were likely to have identical electrophoretic patterns. Therefore, the electrophoretic karyotype patterns demonstrated by orthogonal-field-alternation gel electrophoresis can be used to designate a strain for epidemiologic studies. Images PMID:3290238

  7. Rapid fabrication of reconstructible hydrogels by electrophoretic microbead adhesion.

    PubMed

    Asoh, Taka-Aki; Kikuchi, Akihiko

    2012-10-14

    Hydrogel constructs were rapidly fabricated via the electrophoretic adhesion of oppositely charged microbeads. The reversible preparation of hydrogel constructs was achieved by the reconstruction of microbead networks.

  8. Water permeability of polyunsaturated lipid membranes measured by 17O NMR.

    PubMed

    Huster, D; Jin, A J; Arnold, K; Gawrisch, K

    1997-08-01

    Diffusion-controlled water permeation across bilayers of polyunsaturated phospholipids was measured by 17O nuclear magnetic resonance. In 100-nm extruded liposomes containing 50 mM MnCl2, water exchange between internal and external solutions was monitored via changes in the linewidth of the 17O water resonance of external water. Liposome size and shape were characterized by light scattering methods and determination of liposome trapped volume. At 25 degrees C, the following water permeability coefficients were determined: 18:0-18:1n-9 PC, 155 +/- 24 microns/s; 18:0-18:3n-3 PC, 330 +/- 88 microns/s; and 18:0-22:6n-3 PC, 412 +/- 91 microns/s. The addition of 1 M ethanol reduced permeability coefficients to 66 +/- 15 microns/s for 18:0-18:1n-9 PC and to 239 +/- 67 microns/s for 18:0-22:6n-3 PC. Furthermore, the addition of 50 mol% 18:1n-9-18:1n-9 PE reduced the water permeability from 122 +/- 21 microns/s for pure 18:1n-9-18:1n-9 PC to 74 +/- 15 microns/s for the mixture. The significant increase in water permeation for membranes with polyunsaturated hydrocarbon chains correlates with looser packing of polyunsaturated lipids at the lipid-water interface and the suggested deeper penetration of water into these bilayers. Ethanol may block water diffusion pathways by occupying points of water entry into bilayers at the interface. The addition of dioleoylphosphatidylethanolamine increases lipid packing density and, consequently, reduces permeation rates.

  9. “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

  10. 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.

  11. 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.

  12. 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.

  13. Measuring small compartment dimensions by probing diffusion dynamics via Non-uniform Oscillating-Gradient Spin-Echo (NOGSE) NMR

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Noninvasive measurements of microstructure in materials, cells, and in biological tissues, constitute a unique capability of gradient-assisted NMR. Diffusion-diffraction MR approaches pioneered by Callaghan demonstrated this ability; Oscillating-Gradient Spin-Echo (OGSE) methodologies tackle the demanding gradient amplitudes required for observing diffraction patterns by utilizing constant-frequency oscillating gradient pairs that probe the diffusion spectrum, D(ω). Here we present a new class of diffusion MR experiments, termed Non-uniform Oscillating-Gradient Spin-Echo (NOGSE), which dynamically probe multiple frequencies of the diffusion spectral density at once, thus affording direct microstructural information on the compartment's dimension. The NOGSE methodology applies N constant-amplitude gradient oscillations; N - 1 of these oscillations are spaced by a characteristic time x, followed by a single gradient oscillation characterized by a time y, such that the diffusion dynamics is probed while keeping (N - 1)x + y ≡ TNOGSE constant. These constant-time, fixed-gradient-amplitude, multi-frequency attributes render NOGSE particularly useful for probing small compartment dimensions with relatively weak gradients - alleviating difficulties associated with probing D(ω) frequency-by-frequency or with varying relaxation weightings, as in other diffusion-monitoring experiments. Analytical descriptions of the NOGSE signal are given, and the sequence's ability to extract small compartment sizes with a sensitivity towards length to the sixth power, is demonstrated using a microstructural phantom. Excellent agreement between theory and experiments was evidenced even upon applying weak gradient amplitudes. An MR imaging version of NOGSE was also implemented in ex vivo pig spinal cords and mouse brains, affording maps based on compartment sizes. The effects of size distributions on NOGSE are also briefly analyzed.

  14. Analysis of the interfacial properties of fibrillated and nonfibrillated oral streptococcal strains from electrophoretic mobility and titration measurements: evidence for the shortcomings of the 'classical soft-particle approach'.

    PubMed

    Duval, Jérôme F L; Busscher, Henk J; van de Belt-Gritter, Betsy; van der Mei, Henny C; Norde, Willem

    2005-11-22

    Chemical and structural intricacies of bacterial cells complicate the quantitative evaluation of the physicochemical properties pertaining to the cell surface. The presence of various types of cell surface appendages has a large impact on those properties and therefore on various interfacial phenomena, such as aggregation and adhesion. In this paper, an advanced analysis of the electrophoretic mobilities of fibrillated and nonfibrillated strains (Streptococcus salivarius HB and Streptococcus salivarius HB-C12, respectively) is performed over a wide range of pH and ionic strength conditions on the basis of a recent electrokinetic theory for soft particles. The latter extends the approximate formalism originally developed by Ohshima by solving rigorously the fundamental electrokinetic equations without restrictions on the bacterial size, charge, and double layer thickness. It further allows (i) a straightforward implementation of the dissociation characteristics, as evaluated from titration experiments, of the ionogenic charged groups distributed throughout the bacterial cell wall and/or the surrounding exopolymer layer and (ii) the inclusion of possible specific interactions between the charged groups and ions from the background electrolyte other than charge-determining ions. The theory also enables an estimation of possible swelling/shrinking processes operating on the outer polymeric layer of the bacterium. Application of the electrokinetic model to HB and HB-C12 clearly shows a significant discrepancy between the amount of surface charges probed by electrophoresis and by protolytic titration. This is ascribed to the specific adsorption of cations onto pristine charged sites in the cell wall. Physicochemical parameters pertaining to the hydrodynamics (softness degree) and electrostatics of the bacterial cell wall (HB-C12) and soft polymeric layer (HB) are quantitatively derived.

  15. 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.

  16. 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)

    Dietrich, P.; Werban, U.; Schrön, M.; Walsh, D. O.; Grunewald, E. D.; Pohle, M.; Kathage, S.

    2015-12-01

    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.

  17. 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.

  18. Arylsulfatase A: Relationship of genotype to variant electrophoretic properties

    SciTech Connect

    Park, D.S.; Poretz, R.D.; Ricketts, M.H.; Manowitz, P.

    1996-04-01

    Previous work has shown that specific electrophoretic variants of arylsulfatase A occur more frequently among alcoholic patients than among psychiatric and normal controls. The present study sequenced the gene for two of these electrophoretic variants, IIIa and IIIb. Both contain an A-to-G transition corresponding to substitution of Asn{sub 350} by Ser, with the resulting loss of an N -glycosylation site. The difference in electrophoretic mobility of their gene products is due to a mutation in the IIIb gene resulting in the replacement of Arg{sub 496} by His. Evidence is presented that individuals posessing either of two other electrophoretic variants, Va and Vb, are heterozygous for a normal ASA allele and either a IIIa or IIIb allele, respectively. Thus, the relationship between the phenotype of the electrophoretic banding patterns, IIIa, IIIb, Va, and Vb, and their corresponding genotypes has been elucidated. 18 refs., 5 figs., 1 tab.

  19. Investigation of the free flow electrophoretic process

    NASA Technical Reports Server (NTRS)

    Weiss, R. A.; Lanham, J. W.; Richman, D. W.; Walker, C. D.

    1980-01-01

    The effects of gravity on the free flow electrophoretic process was demonstrated. The free flow electrophoresis chamber used to demonstrate the effects of gravity on the process was of a proprietary design. This chamber was 120 cm long, 16 cm wide, and 0.15 cm thick. Flow in this chamber was in the upward direction and exited through 197 outlets at the top of the chamber. During electrophoresis a stream of sample was injected into the flow near the bottom of the chamber and an electrical field was applied across the width of the chamber. The field caused a lateral force on particles in the sample proportional to the inherent change of the particle and the electric field strength. Particle lateral velocity was then dependent on the force due to viscous drag which was proportional to particle size and particle shape dependent.

  20. Chromatographic and electrophoretic approaches in ink analysis.

    PubMed

    Zlotnick, J A; Smith, F P

    1999-10-15

    Inks are manufactured from a wide variety of substances that exhibit very different chemical behaviors. Inks designed for use in different writing instruments or printing methods have quite dissimilar components. Since the 1950s chromatographic and electrophoretic methods have played important roles in the analysis of inks, where compositional information may have bearing on the investigation of counterfeiting, fraud, forgery, and other crimes. Techniques such as paper chromatography and electrophoresis, thin-layer chromatography, high-performance liquid chromatography, gas chromatography, gel electrophoresis, and the relatively new technique of capillary electrophoresis have all been explored as possible avenues for the separation of components of inks. This paper reviews the components of different types of inks and applications of the above separation methods are reviewed. PMID:10572985

  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. Electrostatic properties of maghemite (γ- Fe(2)O(3)) nanocrystalline quantum dots determined by electrophoretic deposition.

    PubMed

    Islam, Mohammad A; Xia, Shengguo

    2009-07-15

    We applied a DC electric field between two flat electrodes to attract thermally charged maghemite (γ-Fe(2)O(3)) nanocrystalline quantum dots dissolved in hexane to form smooth, robust, large area and apparently identical films of equal thickness on both electrodes. Visible microscopy, scanning electron microscopy, atomic force microscopy and profilometry showed that the electrophoretically deposited dot films were very smooth with an rms roughness of ∼10 nm for ∼0.2 µm thick films. The films were of high quality. They did not re-dissolve in hexane (as do those formed by dry casting), which is a good solvent for these dots, or in common cleaning solvents such as water, alcohols and acetone. The deposition on both electrodes implies there are both positively and negatively thermally charged dots, unlike conventional electrophoretic deposition. We used simple thermodynamics to explain the results of electrophoretic deposition macroscopically. To connect the macroscopic nature of the deposition to the microscopic nature of the dots we performed electrophoretic mobility measurements of the dots and the results seem to complement the thermodynamic treatment.

  6. Electrostatic properties of maghemite (γ- Fe2O3) nanocrystalline quantum dots determined by electrophoretic deposition

    NASA Astrophysics Data System (ADS)

    Islam, Mohammad A.; Xia, Shengguo

    2009-07-01

    We applied a DC electric field between two flat electrodes to attract thermally charged maghemite (γ-Fe2O3) nanocrystalline quantum dots dissolved in hexane to form smooth, robust, large area and apparently identical films of equal thickness on both electrodes. Visible microscopy, scanning electron microscopy, atomic force microscopy and profilometry showed that the electrophoretically deposited dot films were very smooth with an rms roughness of ~10 nm for ~0.2 µm thick films. The films were of high quality. They did not re-dissolve in hexane (as do those formed by dry casting), which is a good solvent for these dots, or in common cleaning solvents such as water, alcohols and acetone. The deposition on both electrodes implies there are both positively and negatively thermally charged dots, unlike conventional electrophoretic deposition. We used simple thermodynamics to explain the results of electrophoretic deposition macroscopically. To connect the macroscopic nature of the deposition to the microscopic nature of the dots we performed electrophoretic mobility measurements of the dots and the results seem to complement the thermodynamic treatment.

  7. Electrostatic properties of maghemite (γ- Fe(2)O(3)) nanocrystalline quantum dots determined by electrophoretic deposition.

    PubMed

    Islam, Mohammad A; Xia, Shengguo

    2009-07-15

    We applied a DC electric field between two flat electrodes to attract thermally charged maghemite (γ-Fe(2)O(3)) nanocrystalline quantum dots dissolved in hexane to form smooth, robust, large area and apparently identical films of equal thickness on both electrodes. Visible microscopy, scanning electron microscopy, atomic force microscopy and profilometry showed that the electrophoretically deposited dot films were very smooth with an rms roughness of ∼10 nm for ∼0.2 µm thick films. The films were of high quality. They did not re-dissolve in hexane (as do those formed by dry casting), which is a good solvent for these dots, or in common cleaning solvents such as water, alcohols and acetone. The deposition on both electrodes implies there are both positively and negatively thermally charged dots, unlike conventional electrophoretic deposition. We used simple thermodynamics to explain the results of electrophoretic deposition macroscopically. To connect the macroscopic nature of the deposition to the microscopic nature of the dots we performed electrophoretic mobility measurements of the dots and the results seem to complement the thermodynamic treatment. PMID:21828514

  8. 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

  9. In vivo measurement of the size of oil bodies in plant seeds using a simple and robust pulsed field gradient NMR method.

    PubMed

    Gromova, Marina; Guillermo, Armel; Bayle, Pierre-Alain; Bardet, Michel

    2015-04-01

    An easy to implement and convenient method to measure the mean size of oil bodies (OBs) in plant seeds is proposed using a pulsed field gradient nuclear magnetic resonance (PFGNMR) approach. PFGNMR is a well-known technique used to study either free or restricted diffusion of molecules. As triacylglycerols (TAG) are confined in OBs, analysis of their diffusion properties is a well-suited experimental approach to determine OB sizes. In fact, at long diffusion time, TAG mean squared displacement is limited by the size of the domain where these molecules are confined. In order to access the OB size distribution, strong intensities of magnetic field gradients are generally required. In this work we demonstrate for the first time that a standard liquid-phase NMR probe equipped with a weak-intensity gradient coil can be used to determine the mean size of OBs. Average sizes were measured for several seeds, and OB diameters obtained by PFGNMR were fully consistent with previously published values obtained by microscopy techniques. Moreover, this approach provided evidence of TAG transfer through the network of interconnected OBs, which is dependent on the ability of adjacent membranes to open diffusion routes between OBs. The main advantage of the NMR method is that it does not require any sample preparation and experiments are performed with whole seeds directly introduced in a standard NMR tube.

  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. 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.

  12. 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.

  13. 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.

  14. Transport properties investigation of aqueous protic ionic liquid solutions through conductivity, viscosity, and NMR self-diffusion measurements.

    PubMed

    Anouti, Mérièm; Jacquemin, Johan; Porion, Patrice

    2012-04-12

    We present a study on the transport properties through conductivity (σ), viscosity (η), and self-diffusion coefficient (D) measurements of two pure protic ionic liquids--pyrrolidinium hydrogen sulfate, [Pyrr][HSO(4)], and pyrrolidinium trifluoroacetate, [Pyrr][CF(3)COO]--and their mixtures with water over the whole composition range at 298.15 K and atmospheric pressure. Based on these experimental results, transport mobilities of ions have been then investigated in each case through the Stokes-Einstein equation. From this, the proton conduction in these PILs follows a combination of Grotthuss and vehicle-type mechanisms, which depends also on the water composition in solution. In each case, the displacement of the NMR peak attributed to the labile proton on the pyrrolidinium cation with the PILs concentration in aqueous solution indicates that this proton is located between the cation and the anion for a water weight fraction lower than 8%. In other words, for such compositions, it appears that this labile proton is not solvated by water molecules. However, for higher water content, the labile protons are in solution as H(3)O(+). This water weight fraction appears to be the solvation limit of the H(+) ions by water molecules in these two PILs solutions. However, [Pyrr][HSO(4)] and [Pyrr][CF(3)COO] PILs present opposed comportment in aqueous solution. In the case of [Pyrr][CF(3)COO], η, σ, D, and the attractive potential, E(pot), between ions indicate clearly that the diffusion of each ion is similar. In other words, these ions are tightly bound together as ion pairs, reflecting in fact the importance of the hydrophobicity of the trifluoroacetate anion, whereas, in the case of the [Pyrr][HSO(4)], the strong H-bond between the HSO(4)(-) anion and water promotes a drastic change in the viscosity of the aqueous solution, as well as on the conductivity which is up to 187 mS·cm(-1) for water weight fraction close to 60% at 298 K.

  15. Advanced NMR characterization of zeolite catalysts

    NASA Astrophysics Data System (ADS)

    Welsh, L. B.

    1985-04-01

    The program discussed in this report is a two-year two-phase joint UOP-University of Illinois study of the application of improved high resolution solid state nuclear magnetic resonance (NMR) techniques to the characterization of zeolite catalysts. During the first phase of this program very pure, and in some cases isotopically enriched faujasites will be prepared and studied by magic angle sample spinning NMR (MASS NMR) and variable engine sample spinning NMR (VASS NMR) on 500 and 360 MHz (proton frequency) NMR spectrometers. The NMR techniques that will be emphasized are the measurement and analysis of the (17)O NMR properties, (27)Al NMR intensity quantitation, and (27)Al and (29)Si NMR relaxation rates. During the second phase of this program these NMR techniques will be used to study the effects of impurity concentration, dealumination treatments and cation exchange on the NMR properties of faujasites. The initial emphasis of this program during Phase I is on the preparation and measurement of the NMR properties of (17)O enriched Na-Y faujasties.

  16. Achievement of 1020MHz NMR.

    PubMed

    Hashi, Kenjiro; Ohki, Shinobu; Matsumoto, Shinji; Nishijima, Gen; Goto, Atsushi; Deguchi, Kenzo; Yamada, Kazuhiko; Noguchi, Takashi; Sakai, Shuji; Takahashi, Masato; Yanagisawa, Yoshinori; Iguchi, Seiya; Yamazaki, Toshio; Maeda, Hideaki; Tanaka, Ryoji; Nemoto, Takahiro; Suematsu, Hiroto; Miki, Takashi; Saito, Kazuyoshi; Shimizu, Tadashi

    2015-07-01

    We have successfully developed a 1020MHz (24.0T) NMR magnet, establishing the world's highest magnetic field in high resolution NMR superconducting magnets. The magnet is a series connection of LTS (low-Tc superconductors NbTi and Nb3Sn) outer coils and an HTS (high-Tc superconductor, Bi-2223) innermost coil, being operated at superfluid liquid helium temperature such as around 1.8K and in a driven-mode by an external DC power supply. The drift of the magnetic field was initially ±0.8ppm/10h without the (2)H lock operation; it was then stabilized to be less than 1ppb/10h by using an NMR internal lock operation. The full-width at half maximum of a (1)H spectrum taken for 1% CHCl3 in acetone-d6 was as low as 0.7Hz (0.7ppb), which was sufficient for solution NMR. On the contrary, the temporal field stability under the external lock operation for solid-state NMR was 170ppb/10h, sufficient for NMR measurements for quadrupolar nuclei such as (17)O; a (17)O NMR measurement for labeled tri-peptide clearly demonstrated the effect of high magnetic field on solid-state NMR spectra. PMID:25978708

  17. 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.

  18. Tracer diffusion measurements in solid lithium: a test case for the comparison between NMR in static and pulsed magnetic field gradients after upgrading a standard solid state NMR spectrometer.

    PubMed

    Marion Fischer, D; Duwe, Peter; Indris, Sylvio; Heitjans, Paul

    2004-09-01

    This paper reports on the upgrading of a standard solid state NMR spectrometer, which has been used in combination with a field variable 7 T cryomagnet, to a low-cost combined SFG and PFG NMR spectrometer. Both methods are applied to solid lithium as a simple test case. The results show that under the given conditions SFG NMR and PFG NMR can provide tracer diffusion coefficients for 7 Li diffusion down to about 10(-14) and 10(-13) m2/s, respectively. SFG and PFG NMR are complementary methods. The paper demonstrates advantages and disadvantages of each method with a concrete example and why it is desirable to be able to apply both methods to the same sample.

  19. Electrophoretic transfer of proteins across polyacrylamide membranes.

    PubMed

    Rylatt, D B; Napoli, M; Ogle, D; Gilbert, A; Lim, S; Nair, C H

    1999-12-31

    The electrophoretic transfer of purified proteins has been examined in a Gradiflow "Babyflow BF100" unit. A number of factors affect protein separation within this preparative electrophoresis system. We established that the rate of protein transfer was proportional to the applied voltage. The transfer is slowest at the isoelectric point (pI) and increased the further away the pH was from the pI of the protein. Protein transfer was found to be independent of the ionic strength of the buffer, for buffers that excluded the addition of strong acids or strong bases or sodium chloride. Transfer decreased as the pore size of the membrane decreased. Finally, transfer was inhibited at high salt concentrations in the protein solution, but remained unaffected when urea and non-ionic detergents were added to the solution. To increase the speed of protein separations, buffers with low conductivity should be used. A pH for the optimal separation should be selected on the basis of the relative pI and size of the target proteins and that of the major contaminants. PMID:10674937

  20. 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.

  1. Tubulin evolution: an electrophoretic and immunological analysis.

    PubMed

    Adoutte, A; Claisse, M; Cance, J

    1984-03-01

    This paper summarizes a survey of the electrophoretic behavior of the tubulins of 23 species (mostly protists) as well as their reactivity towards 4 anti-tubulin antibodies (raised against two ciliate tubulins and two vertebrate ones). Some generalizations concerning the relative migration rates of alpha VS beta tubulin could be made, in particular the alpha/beta inversion, first described in Physarum was extended to several ciliates. Antivertebrate tubulin antibodies displayed a very broad spectrum of reactions, reacting with virtually all the species tested. They appear to correspond to auto-antibodies no exclusively directed against species specific determinants. In contrast, the two anti-ciliate tubulin antibodies displayed a narrow species specificity reacting only with a limited subset of protists. They were shown to be specific for a small number of immunological determinants present on ciliate tubulins. This allowed a rough evaluation of evolutionary relatedness between the various groups of protists analyzed. The results are discussed within the framework of a number of published phyllogenies and shown to be in striking agreement with some of the schemes.

  2. Capillary electrophoretic behavior of seven sulfonylureas.

    PubMed

    Matchett, W H; Winnik, W; Brumley, W C

    1996-01-01

    The electrophoretic behavior of seven sulfonylureas (bensulfuron methyl, sulfometuron methyl, nicosulfuron [accent], chlorimuron ethyl, thifensulfuron methyl [harmony], metsulfuron methyl, and chlorsulfuron) was studied under capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) conditions. Mixtures of these compounds were separated with very high efficiencies (2 x 10(5) theoretical plates) in a running buffer consisting of 3 parts acetate buffer (25 mM, pH 5.0) and 1 part acetonitrile. In this buffer system, acetonitrile was shown to be superior to methanol, acetone, and ethanol as a nonpolar additive, but any of these solvents can be used to reduce electroosmotic flow (EOF) and to obtain adequate separation. On-column detection limits at 214 nM were of the order of 80-100 fM. Micellar agents such as sodium dodecyl sulfate (SDS) and sodium cholate (but not monosialoganglioside-Gm1 or starburst dendrimer, generation 2.5) improved separation in phosphate and borate buffers. Implications of these results for the development of methods to detect these compounds on matrices of environmental origin are discussed. In particular, the instability of these compounds in methanol is noted and degradation products are detected using free zone CE. The methanolysis products of sulfometuron are tentatively identified by tandem MS (negative ion conditions) as 2-amino-4,6-dimethylpyrimidine and 2-carboxymethylbenz(N-carboxymethyl)sulfonamide.

  3. Electrophoretic forming of functionally-graded materials

    SciTech Connect

    Sarkar, P.; Datta, S.; Nicholson, P.S.

    1997-12-31

    Electrophoretic deposition (EPD) is a colloidal forming process where electrically charged particles are deposited onto an oppositely-charged electrode from an electrostatically stabilized suspension by the application of a dc electric field. It is a cheap and facile technique to fabricate complicated ceramic shapes. EPD is very effective method to synthesize ceramic/ceramic and metal/ceramic composites, eg.; dispersed, laminar, fibre reinforced, and functionally graded materials (FGM) etc. By EPD it is possible to synthesize step FGMs and continuous profile FGMs. The compositional profile of the FGM can be controlled by deposition current density, second component flow rate, suspension concentration etc. Step and continuous profile Al{sub 2}O{sub 3}/YSZ and continuous profile Al{sub 2}O{sub 3}/MoSi{sub 2}, Al{sub 2}O{sub 3}/Ni and YSZ/Ni fabrication is reported herein. The microstructures of the FGMs produced were characterized by optical/electron microscopy and micro-indentation was used to quantify the Vicker`s hardness and fracture toughness variation across The FGM sections.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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...

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

    PubMed Central

    Popovici, Jonathan; Lytle, Darren A.; Adcock, Noreen J.; Rice, Eugene W.

    2012-01-01

    The electrophoretic mobility (EPM) of endospores of Bacillus anthracis and surrogates was 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 provide new insight for Bacillus anthracis surrogate selection and for attachment/detachment and transport studies. PMID:23001659

  11. Enhanced electrophoretic motion using supercapacitor-based energy storage system.

    PubMed

    Liu, Ran; Wong, Flory; Duan, Wentao; Sen, Ayusman

    2013-12-23

    Electrophoretic motion at low potentials is facilitated by redox chemistry occurring in a supercapacitor-based electrochemical energy storage system during charge and discharge. We show that MnO2 -modified electrodes can effectively alleviate the electrode surface polarization, the main factor that leads to inefficient electrophoresis at low voltages. A self-powered electrophoretic system based on a discharging battery has been also fabricated.

  12. 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

  13. 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.

  14. Proton clouds to measure long-range contacts between nonexchangeable side chain protons in solid-state NMR.

    PubMed

    Sinnige, Tessa; Daniëls, Mark; Baldus, Marc; Weingarth, Markus

    2014-03-26

    We show that selective labeling of proteins with protonated amino acids embedded in a perdeuterated matrix, dubbed 'proton clouds', provides general access to long-range contacts between nonexchangeable side chain protons in proton-detected solid-state NMR, which is important to study protein tertiary structure. Proton-cloud labeling significantly improves spectral resolution by simultaneously reducing proton line width and spectral crowding despite a high local proton density in clouds. The approach is amenable to almost all canonical amino acids. Our method is demonstrated on ubiquitin and the β-barrel membrane protein BamA.

  15. 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.

  16. 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

  17. The effects of cholera enterotoxin on intestinal tissue water as measured by nuclear magnetic resonance (NMR) spectroscopy.

    PubMed

    Udall, J N; Alvarez, L A; Nichols, B L; Hazlewood, C F

    1975-01-01

    Cholera enterotoxin has been postulated to change the configuration of the intracellular protein-water system, altering the permeability of the cell to water. Using nuclear magnetic resonance (NMR) spectroscopy, this protein-water relationship can be examined. Small intestinal loops in the rat were injected with 0.5 ml of either Schwarz/Mann cholera enterotoxin (40 mug/cc saline solution) or normal saline. Full thickness segments of intestine from each loop were taken and percentage water (using a gravimetric procedure which includes a correction for fat) and NMR relaxation times were determined. The mean value +/- S.D. for tissue water was 79.49 +/- 2.65% in the controls and 84.52 +/- 2.01% in the cholera specimens (p less than .001). T1 (spin-lattice) relaxation times were 521.22 +/- 69.5 msec in the controls and 667.96 +/- 119.25 msec in cholera tissue (p less than .001). T2 (spin-spin) relaxation times were 62.34 +/- 9.59 msec in controls and 80.35 +/- 21.46 msec in cholera tissue (p less than .02). These findings are consistent with the theory that cholera enterotoxin acts to alter intracellular protein-water relationship.

  18. 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

  19. Quantitative attachment and detachment of bacterial spores from fine wires through continuous and pulsed DC electrophoretic deposition.

    PubMed

    Zhou, Wenbo; Watt, Sarah K; Tsai, De-Hao; Lee, Vincent T; Zachariah, Michael R

    2013-02-14

    We demonstrate the uniform attachment of bacterial spores electrophoretically onto fine wires in liquids and subsequently quantitatively detached back into suspension. It was found that the use of a pulsed voltage method resulted in a uniform coverage of spores and prevented visible bubble formation resulting from water electrolysis which tended to dislodge the spores from the wires. By monitoring the electrophoretically derived current, this method could also be used to quantitatively measure the surface charges on spores and the deposition rate. The method is generic and should be applicable to the deposition of any charged biological material (e.g., spores, bacteria, viruses) onto metal surfaces.

  20. Achievement of a 920-MHz High Resolution NMR

    NASA Astrophysics Data System (ADS)

    Hashi, Kenjiro; Shimizu, Tadashi; Goto, Atsushi; Kiyoshi, Tsukasa; Matsumoto, Shinji; Wada, Hitoshi; Fujito, Teruaki; Hasegawa, Ken-ichi; Yoshikawa, Masatoshi; Miki, Takashi; Ito, Satoshi; Hamada, Mamoru; Hayashi, Seiji

    2002-06-01

    We have developed a 920-MHz NMR system and performed the proton NMR measurement of H 2O and ethylbenzene using the superconducting magnet operating at 21.6 T (920 MHz for proton), which is the highest field produced by a superconducting NMR magnet in the persistent mode. From the NMR measurements, it is verified that both homogeneity and stability of the magnet have a specification sufficient for a high resolution NMR.

  1. 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

  2. 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+.

  3. 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

  4. Quantitative measurement of major secoiridoid derivatives in olive oil using qNMR. Proof of the artificial formation of aldehydic oleuropein and ligstroside aglycon isomers.

    PubMed

    Karkoula, Evangelia; Skantzari, Angeliki; Melliou, Eleni; Magiatis, Prokopios

    2014-01-22

    A previously developed method for measurement of oleocanthal and oleacein in olive oil by quantitative (1)H NMR was expanded to include the measurement of the monoaldehydic forms of oleuropein and ligstroside aglycons. The method was validated and applied to the study of 340 monovarietal Greek and Californian olive oils from 23 varieties and for a 3-year period. A wide variation concerning the concentrations of all four secoiridoids was recorded. The concentration of each one ranged from nondetectable to 711 mg/kg and the sum of the four major secoiridoids (named as D3) ranged from nondetectable to 1534 mg/kg. Examination of the NMR profile of the olive oil extract before and after contact with normal or reversed stationary chromatography phase proved the artificial formation of the 5S,8S,9S aldehydic forms of oleuropein and ligstroside aglycon isomers during chromatography. Finally, methyl elenolate was identified for the first time as a minor constituent of olive oil. PMID:24384036

  5. 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

  6. 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

  7. Measurement of Internal Acyl Migration Reaction Kinetics Using Directly Coupled HPLC-NMR:  Application for the Positional Isomers of Synthetic (2-Fluorobenzoyl)-d-glucopyranuronic Acid.

    PubMed

    Sidelmann, U G; Hansen, S H; Gavaghan, C; Carless, H A; Lindon, J C; Farrant, R D; Wilson, I D; Nicholson, J K

    1996-08-01

    Ester glucuronides (1-O-acyl-β-d-glucopyranuronates) of many drugs may undergo internal acyl migration reactions, resulting in the formation of new positional isomers with both α- and β-anomers. We illustrate here a novel approach for the direct investigation of the acyl migration kinetics of ester glucuronides and show the application with respect to the isomers of synthetic (2-fluorobenzoyl)-d-glucopyranuronic acid. Individual isomers were separated from an equilibrium mixture containing the β-1-O-acyl, α- and β-2-O-acyl, α- and β-3-O-acyl, and α- and β-4-O-acyl isomers at pH 7.4 in 20 mM phosphate buffer. The interconverting isomers were separated using reversed-phase HPLC and pumped directly into a dedicated on-line NMR flow probe in a 600 MHz NMR spectrometer. The flow was stopped with each isomer in the NMR flow probe, and sequential NMR spectra were collected at 25 °C, allowing direct measurement of the production of positional isomers from each selectively isolated glucuronide isomer. All of the positional isomers and anomers were characterized, and relative quantities determined, and a kinetic model describing the rearrangement reactions was constructed. The acyl migration reaction kinetics were simulated using a theoretical approach using nine first-order rate constants determined for the acyl migration reactions and six first-order rate constants describing the mutarotation each of the 2-, 3-, and 4-positional isomers. The rate constants (in h(-)(1)) for the rearrangement reactions of the 2-fluorobenzoyl glucuronide isomers were as follows:  β-1-O-acyl, 0.29 ± 0.01; α-2-O-acyl, 0.11 ± 0.01; β-2-O-acyl, 0.07 ± 0.01; α-3-O-acyl, 0.10 ± 0.01; β-3-O-acyl, 0.09 ± 0.01; α-4-O-acyl, 0.09 ± 0.01; and β-4-O-acyl, 0.06 ± 0.01. The α- and β-anomerization rates were estimated on the basis of the kinetics model; the anomerization rates of the 4-O-acyl isomers were additionally determined experimentally using directly coupled HPLC-NMR. The

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

    DOE PAGES

    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

  9. 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

  10. 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.

  11. 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.

  12. Development of the Resolution Theory for Electrophoretic Exclusion

    PubMed Central

    Kenyon, Stacy M.; Keebaugh, Michael W.; Hayes, Mark A.

    2015-01-01

    Electrophoretic exclusion, a technique that differentiates species in bulk solution near a channel entrance, has been demonstrated on benchtop and microdevice designs. In these systems, separation occurs when the electrophoretic velocity of one species is greater than the opposing hydrodynamic flow, while the velocity of the other species is less than that flow. Although exclusion has been demonstrated in multiple systems for a range of analytes, a theoretical assessment of resolution has not been addressed. To compare the results of these calculations to traditional techniques, the performance is expressed in terms of smallest difference in electrophoretic mobilities that can be completely separated (R = 1.5). The calculations indicate that closest resolvable species (Δμmin) differ by approximately 10−13 m2/Vs and peak capacity (nc) is 1000. Published experimental data is compared to these calculated results. PMID:24916305

  13. 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.

  14. 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.

  15. 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.

  16. 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.

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

    DOE PAGES

    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

  18. 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.

  19. Dynamic High-Resolution H-1 and P-31 NMR Spectroscopy and H-1 T-2 Measurements in Postmortem Rabbit Muscles Using Slow Magic Angle Spinning

    SciTech Connect

    Bertram, Hanne Christine; Hu, Jian Zhi; Rommereim, Donald N.; Wind, Robert A.; Andersen, Henrik J.

    2004-05-05

    Postmortem changes in rabbit muscle tissue with different glycogen status (normal vs low) were followed continuously from 13 min postmortem until 8 h postmortem and again 20 h postmortem using simultaneous magic angle spinning 1H and 31P NMR spectroscopy together with measurement of the transverse relaxation time, T2, of the muscle water. The 1H metabolite spectra were measured using the phase-altered spinning sidebands (PASS) technique at a spinning rate of 40 Hz. pH values calculated from the 31P NMR spectra using the chemical shifts of the C-6 line of histidine in the 1H spectra and the chemical shifts of inorganic phosphate in the 31P spectra confirmed the different muscle glycogen status in the tissues. High-resolution 1H spectra obtained from the PASS technique revealed the presence of a new resonance line at 6.8 ppm during the postmortem period, which were absent in muscles with low muscle glycogen content. This new resonance line may originate from the aminoprotons in creatine, and its appearance may be a result of a pH effect on the exchange rate between the amino and the water protons and thereby the NMR visibility. Alternatively, the new resonance line may originate from the aromatic protons in tyrosine, and its appearance may be a result of a pH-induced protein unfolding exposing hydrophobic amino acid residues to the aqueous environment. Further studies are needed to evaluate these hypotheses. Finally, distributed analysis of the water T2 relaxation data revealed three relaxation populations and an increase in the population believed to reflect extramyofibrillar water through the postmortem period. This increase was significantly reduced (p < 0.0001) in samples from animals with low muscle glycogen content, indicating that the pH is controlling the extent of postmortem expulsion of water from myofibrillar structures. The significance of the postmortem increase in the amount extramyofibrillar water on the water-holding capacity was verified by

  20. 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

  1. 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

  2. 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.

  3. 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 §...

  4. 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 §...

  5. 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 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 §...

  6. 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 §...

  7. 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 §...

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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…

  13. Electrophoretically deposited graphene oxide and carbon nanotube composite for electrochemical capacitors.

    PubMed

    Ajayi, Obafunso A; Guitierrez, Daniel H; Peaslee, David; Cheng, Arthur; Gao, Theodore; Wong, Chee Wei; Chen, Bin

    2015-10-16

    We report a scalable one-step electrode fabrication approach for synthesizing composite carbon-based supercapacitors with synergistic outcomes. Multi-walled carbon nanotubes (MWCNTs) were successfully integrated into our modified electrophoretic deposition process to directly form composite MWCNT-GO electrochemical capacitor electrodes (where GO is graphene oxide) with superior performance to solely GO electrodes. The measured capacitance improved threefold, reaching a maximum specific capacitance of 231 F g(-1). Upon thermal reduction, MWCNT-GO electrode sheet resistance decreased by a factor of 8, significantly greater than the 2× decrease of those without MWCNTs.

  14. 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

  15. Experimental data and theoretical predictions for the rate of electrophoretic clarification of colloidal suspensions

    SciTech Connect

    Johnson, T.J.; Davis, E.J.

    2000-05-01

    An experimental and theoretical investigation of the electrophoretic clarification rate of colloidal suspensions was conducted. The suspensions included a coal-washing effluent and a model system of TiO{sub 2} particles. A parametric study of TiO{sub 2} suspensions was performed to validate and analysis of the electrophoretic motion of the clarification front formed between a clear zone and the suspension. To measure the electric field strength needed in the prediction of the location of the front, a moveable probe and salt bridge were connected to a reference electrode. Using the measured electric field strengths, it was found that the numerical solution to the unit cell electrophoresis model agrees with the measured clarification rates. For suspensions with moderately thick electric double layers and high particle volume fractions the deviations from classical Smoluchowski theory are substantial, and the numerical analysis is in somewhat better agreement with the data than a prior solution of the problem. The numerical model reduces to the predictions of previous theories as the thickness of the electric double layer decreases, and it is in good agreement with the clarification rate measured for a coal-washing effluent suspension with thin electric double layers.

  16. 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…

  17. 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%.

  18. 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

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

    PubMed

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

    2015-08-25

    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.

  20. 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

  1. Review of advances in coupling electrochemistry and liquid state NMR.

    PubMed

    Bussy, Ugo; Boujtita, Mohammed

    2015-05-01

    The coupling of electrochemistry and NMR spectroscopy (EC-NMR) may present an interesting approach in the environmental oxidative degradation or metabolism studies. This review presents experimental advances in the field of EC-NMR and highlights the main advantages and drawbacks of in situ and on line of NMR spectroelectrochemistry. The analysis of NMR spectra recorded in situ or on line EC-NMR permits to elucidate the reaction pathway of the electrochemical oxidation reactions and could constitute a fast way for monitoring unstable species as for instance quinone and quinone imine structures without using any coupling agents. The use of 1D and 2D NMR coupled with electrochemistry may leads to the elucidation of the major species produced from the electrochemical oxidation process. The present review gives an overview about the development of the electrochemical cells which can operate on line or in situ with NMR measurements. Future developments and potential applications of EC-NMR are also discussed.

  2. 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...

  3. 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.

  4. Properties of poly(styrene/alpha-tert-butoxy-omega-vinylbenzyl-polyglycidol) microspheres suspended in water. Effect of sodium chloride and temperature on particle diameters and electrophoretic mobility.

    PubMed

    Basinska, Teresa; Slomkowski, Stanislaw; Kazmierski, Slawomir; Chehimi, Mohamed M

    2008-08-19

    Hydrodynamic and electrophoretic properties of core-shell poly(styrene/alpha- tert-butoxy-omega-vinylbenzyl-polyglycidol) (P(S/PGL)) microspheres suspended in water are described. The microspheres were obtained by surfactant-free emulsion copolymerization of styrene and alpha- tert-butoxy-omega-vinylbenzyl-polyglycidol macromonomer ( M n = 2800, M w/ M n = 1.05). The process yielded microspheres with number average diameter D n = 270 nm and with low diameter dispersity index D w/ D n = 1.01. Shells of P(S/PGL) microspheres were enriched in polyglycidol. Molar fraction of polyglycidol monomeric units in the shells (determined by X-ray photoelectron spectroscopy) was equal to 0.34, which is much higher than the average molar fraction of polyglycidol monomeric units in whole particles of 0.048. Influences of NaCl concentration and temperature on P(S/PGL) microsphere diameters and on their electrophoretic mobility were investigated. It was found that hydrodynamic diameter of P(S/PGL) microspheres, determined by photon correlation spectroscopy, decreased significantly when temperature did exceed a certain value (transition temperature, T t). It has been found that the decrease is more pronounced for higher concentrations of NaCl in the medium. For microspheres suspended in 10 (-1) M NaCl, the hydrodynamic diameter decreased by 8% whereas for the same particles in pure water the diameter decreased by 5.2%. The process of shrinkage was fully reversible. Values of T t for P(S/PGL) microspheres were lower for higher concentrations of NaCl. Adjustment of salt concentration allowed controlling T t in a range from 44.4 to 49.9 degrees C. 13C NMR relaxation time measurements (T 1) for carbon atoms in polyglycidol macromonomer revealed that T 1 did increase with increasing temperature (in temperature range from 25 to 75 degrees C) indicating higher motion of chains at higher temperature. Addition of NaCl did not induce a substantial change of T 1 in the mentioned temperature

  5. 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…

  6. Quantitative 2D liquid-state NMR.

    PubMed

    Giraudeau, Patrick

    2014-06-01

    Two-dimensional (2D) liquid-state NMR has a very high potential to simultaneously determine the absolute concentration of small molecules in complex mixtures, thanks to its capacity to separate overlapping resonances. However, it suffers from two main drawbacks that probably explain its relatively late development. First, the 2D NMR signal is strongly molecule-dependent and site-dependent; second, the long duration of 2D NMR experiments prevents its general use for high-throughput quantitative applications and affects its quantitative performance. Fortunately, the last 10 years has witnessed an increasing number of contributions where quantitative approaches based on 2D NMR were developed and applied to solve real analytical issues. This review aims at presenting these recent efforts to reach a high trueness and precision in quantitative measurements by 2D NMR. After highlighting the interest of 2D NMR for quantitative analysis, the different strategies to determine the absolute concentrations from 2D NMR spectra are described and illustrated by recent applications. The last part of the manuscript concerns the recent development of fast quantitative 2D NMR approaches, aiming at reducing the experiment duration while preserving - or even increasing - the analytical performance. We hope that this comprehensive review will help readers to apprehend the current landscape of quantitative 2D NMR, as well as the perspectives that may arise from it.

  7. Supercapacitors using carbon nanotubes films by electrophoretic deposition

    NASA Astrophysics Data System (ADS)

    Du, Chunsheng; Pan, Ning

    Multi-walled carbon nanotube (MWNT) thin films have been fabricated by electrophoretic deposition technique in this study. The supercapacitors built from such thin film electrodes have exhibited near-ideal rectangular cyclic voltammograms even at a scan rate as high as 1000 mV s -1 and a high specific power density over 20 kW kg -1. More importantly, the supercapacitors showed superior frequency response, with a frequency 'knee' at about 7560 Hz, which is more than 70 times higher than the highest 'knee' frequency (100 Hz) so far reported for such supercapacitors. Our study also demonstrated that these carbon nanotube thin films can serve as a coating layer over ordinary current collectors to drastically enhance the electrode performance, indicating the huge potential in supercapacitor and battery manufacturing. Finally, it is clear that electrophoretic deposition is a promising technique for massive fabrication of carbon nanotube electrodes for various electronic devices.

  8. Reversed-polarity capillary zone electrophoretic analysis of usnic acid.

    PubMed

    Kreft, S; Strukelj, B

    2001-08-01

    A capillary zone electrophoretic (CZE) method for the determination of usnic acid is described for the first time. Usnic acid is an antibiotic substance from lichens. Due to its low solubility in water, a high content of methanol in CZE buffer is required. Because of the methanol in the buffer, the electroosmotic flow velocity was lower than the electrophoretic mobility of usnic acid. Accordingly, the use of reversed-polarity (with the anode on the detector side of the capillary) was necessary. The optimal buffer composition was 50 mM NaOH, 20 mM acetic acid and 5% water in methanol. The detection limit of UV detector at 290 nm for usnic acid in the injected extract was 3.5 mg/L and the relative standard deviation of the normalized peak area was 3.3% at 250 mg/L.

  9. Preparation and properties of electrophoretic microcapsules for electronic paper.

    PubMed

    Song, J K; Choi, H J; Chin, I

    2007-02-01

    This paper shows two types of microcapsules used for electrophoretic display. One is prepared by in-situ polymerization which is based on urea, melamine and formaldehyde and another by complex coacervation, which is composed of gelatin and gum Arabic. Microcapsules attract interests of many research groups for longer lifetime of electrophoretic display by reducing agglomerization or lateral movements of nanoparticles. The gelatin microcapsules were more attractive in providing more uniform microcapsule coverage on electrodes due to their flexibility as compared to the melamine-urea microcapsules. The properties of microcapsules were characterized by FTIR, OM, SEM and TGA. Migration of nanoparticles in the two types of microcapsules was also observed when an electric field was applied.

  10. Alternative to polyacrylamide gels improves the electrophoretic mobility shift assay.

    PubMed

    Vanek, P G; Fabian, S J; Fisher, C L; Chirikjian, J G; Collier, G B

    1995-04-01

    In this paper we outline a simplified protocol for the electrophoretic mobility shift assay utilizing TreviGel 500, a nontoxic alternative to polyacrylamide. The TreviGel 500 matrix combines the strength and resolution of polyacrylamide with the simplicity and flexibility of agarose in the casting of gels. Therefore, this method provides a simple, rapid and nontoxic alternative to current protocols for the investigation of protein: DNA interactions.

  11. Recrystallisation of electrophoretically deposited CdTe films

    NASA Astrophysics Data System (ADS)

    Pande, P. C.; Bocking, S.; Duke, S.; Miles, R. W.; Carter, M. J.; Latimer, I. D.; Hill, R.

    1996-02-01

    Films of CdTe have been produced by a novel low cost process based on electrophoretic deposition using polar organic solvents. The main advantage of this method is the high rate of deposition, greater than 20 μm/min. Details of the deposition process are given and the effects of post-deposition annealing of the samples have also been investigated using XRD, SEM and EDAX. Laser annealing resulted in melting of CdTe producing more compact and robust films.

  12. 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.

  13. Direct measurement of oleocanthal and oleacein levels in olive oil by quantitative (1)H NMR. Establishment of a new index for the characterization of extra virgin olive oils.

    PubMed

    Karkoula, Evangelia; Skantzari, Angeliki; Melliou, Eleni; Magiatis, Prokopios

    2012-11-28

    A new method for direct measurement of the oleocanthal and oleacein levels in olive oil by quantitative (1)H NMR was developed. The method was applied to the study of 175 monovarietal commercial Greek and California olive oil samples. The main findings were as follows: (1) There was a significant variation concerning the concentrations of oleocanthal and oleacein among the studied samples. Their concentrations ranged from nondetectable to 355 mg/kg and their sum (index D1) from 0 to 501 mg/kg. (2) There are olive varieties that independent of geographic origin and harvest time produce oil that contains both compounds in low levels. (3) There is a positive correlation of a high level of oleocanthal and oleacein in olive oils with the early time of harvest. Although there is a need for more extensive study, a new index for the characterization of extra virgin olive oils, which is a combination of D1 = oleocanthal + oleacein level and D2 = oleocanthal/oleacein ratio, seems to be very useful. PMID:23116297

  14. Direct measurement of oleocanthal and oleacein levels in olive oil by quantitative (1)H NMR. Establishment of a new index for the characterization of extra virgin olive oils.

    PubMed

    Karkoula, Evangelia; Skantzari, Angeliki; Melliou, Eleni; Magiatis, Prokopios

    2012-11-28

    A new method for direct measurement of the oleocanthal and oleacein levels in olive oil by quantitative (1)H NMR was developed. The method was applied to the study of 175 monovarietal commercial Greek and California olive oil samples. The main findings were as follows: (1) There was a significant variation concerning the concentrations of oleocanthal and oleacein among the studied samples. Their concentrations ranged from nondetectable to 355 mg/kg and their sum (index D1) from 0 to 501 mg/kg. (2) There are olive varieties that independent of geographic origin and harvest time produce oil that contains both compounds in low levels. (3) There is a positive correlation of a high level of oleocanthal and oleacein in olive oils with the early time of harvest. Although there is a need for more extensive study, a new index for the characterization of extra virgin olive oils, which is a combination of D1 = oleocanthal + oleacein level and D2 = oleocanthal/oleacein ratio, seems to be very useful.

  15. Measuring dynamic and kinetic information in the previously inaccessible supra-τ(c) window of nanoseconds to microseconds by solution NMR spectroscopy.

    PubMed

    Ban, David; Sabo, T Michael; Griesinger, Christian; Lee, Donghan

    2013-09-26

    Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool that has enabled experimentalists to characterize molecular dynamics and kinetics spanning a wide range of time-scales from picoseconds to days. This review focuses on addressing the previously inaccessible supra-tc window (defined as τ(c) < supra-τ(c) < 40 μs; in which tc is the overall tumbling time of a molecule) from the perspective of local inter-nuclear vector dynamics extracted from residual dipolar couplings (RDCs) and from the perspective of conformational exchange captured by relaxation dispersion measurements (RD). The goal of the first section is to present a detailed analysis of how to extract protein dynamics encoded in RDCs and how to relate this information to protein functionality within the previously inaccessible supra-τ(c) window. In the second section, the current state of the art for RD is analyzed, as well as the considerable progress toward pushing the sensitivity of RD further into the supra-τ(c) scale by up to a factor of two (motion up to 25 μs). From the data obtained with these techniques and methodology, the importance of the supra-τ(c) scale for protein function and molecular recognition is becoming increasingly clearer as the connection between motion on the supra-τ(c) scale and protein functionality from the experimental side is further strengthened with results from molecular dynamics simulations.

  16. Symmetry of the gradient profile as second experimental dimension in the short-time expansion of the apparent diffusion coefficient as measured with NMR diffusometry.

    PubMed

    Laun, Frederik Bernd; Kuder, Tristan Anselm; Zong, Fangrong; Hertel, Stefan; Galvosas, Petrik

    2015-10-01

    The time-dependent apparent diffusion coefficient as measured by pulsed gradient NMR can be used to estimate parameters of porous structures including the surface-to-volume ratio and the mean curvature of pores. In this work, the short-time diffusion limit and in particular the influence of the temporal profile of diffusion gradients on the expansion as proposed by Mitra et al. (1993) is investigated. It is shown that flow-compensated waveforms, i.e. those whose first moment is zero, are blind to the term linear in observation time, which is the term that is proportional to mean curvature and surface permeability. A gradient waveform that smoothly interpolates between flow-compensated and bipolar waveform is proposed and the degree of flow-compensation is used as a second experimental dimension. This two-dimensional ansatz is shown to yield an improved precision when characterizing the confining domain. This technique is demonstrated with simulations and in experiments performed with cylindrical capillaries of 100 μm radius.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. Using NMR to study full intact wine bottles

    NASA Astrophysics Data System (ADS)

    Weekley, A. J.; Bruins, P.; Sisto, M.; Augustine, M. P.

    2003-03-01

    A nuclear magnetic resonance (NMR) probe and spectrometer capable of investigating full intact wine bottles is described and used to study a series of Cabernet Sauvignons with high resolution 1H NMR spectroscopy. Selected examples of full bottle 13C NMR spectra are also provided. The application of this full bottle NMR method to the measurement of acetic acid content, the detection of complex sugars, phenols, and trace elements in wine is discussed.

  2. NMR investigations of molecular dynamics

    NASA Astrophysics Data System (ADS)

    Palmer, Arthur

    2011-03-01

    NMR spectroscopy is a powerful experimental approach for characterizing protein conformational dynamics on multiple time scales. The insights obtained from NMR studies are complemented and by molecular dynamics (MD) simulations, which provide full atomistic details of protein dynamics. Homologous mesophilic (E. coli) and thermophilic (T. thermophilus) ribonuclease H (RNase H) enzymes serve to illustrate how changes in protein sequence and structure that affect conformational dynamic processes can be monitored and characterized by joint analysis of NMR spectroscopy and MD simulations. A Gly residue inserted within a putative hinge between helices B and C is conserved among thermophilic RNases H, but absent in mesophilic RNases H. Experimental spin relaxation measurements show that the dynamic properties of T. thermophilus RNase H are recapitulated in E. coli RNase H by insertion of a Gly residue between helices B and C. Additional specific intramolecular interactions that modulate backbone and sidechain dynamical properties of the Gly-rich loop and of the conserved Trp residue flanking the Gly insertion site have been identified using MD simulations and subsequently confirmed by NMR spin relaxation measurements. These results emphasize the importance of hydrogen bonds and local steric interactions in restricting conformational fluctuations, and the absence of such interactions in allowing conformational adaptation to substrate binding.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Electrophoretic fabrication of chitosan-zirconium-oxide nanobiocomposite platform for nucleic acid detection.

    PubMed

    Das, Maumita; Dhand, Chetna; Sumana, Gajjala; Srivastava, A K; Nagarajan, R; Nain, Lata; Iwamoto, M; Manaka, Takaaki; Malhotra, B D

    2011-03-14

    The present work describes electrophoretic fabrication of nanostructured chitosan-zirconium-oxide composite (CHIT-NanoZrO(2)) film (180 nm) onto indium-tin-oxide (ITO)-coated glass plate. This nanobiocomposite film has been explored as immobilization platform for probe DNA specific to M. Tuberculosis as model biomolecule to investigate its sensing characteristics. It is revealed that pH-responsive behavior of CHIT and its cationic skeleton is responsible for the movement of CHIT-NanoZrO(2) colloids toward cathode during electrophoretic deposition. The FT-IR, SEM, TEM, and EDX techniques have been employed for the structural, morphological, and composition analysis of the fabricated electrodes. The morphological studies clearly reveal uniform inter-linking and dispersion of hexagonal nanograins of ZrO(2) (30-50 nm) into the chitosan matrix, resulting in homogeneous nanobiocomposite formation. Electrochemical response measurements of DNA/CHIT-NanoZrO(2)/ITO bioelectrode, carried out using cyclic voltammetry and differential pulse voltammetry, reveal that this bioelectrode can specifically detect complementary target DNA up to 0.00078 μM with sensitivity of 6.38 × 10(-6) AμM(-1).

  10. Preparation and characterization of TiO 2-cationic hybrid nanoparticles as electrophoretic particles

    NASA Astrophysics Data System (ADS)

    Li, Jingjing; Deng, Liandong; Xing, Jinfeng; Dong, Anjie; Li, Xianggao

    2012-01-01

    The hybrid nanoparticles (TiO2-HNPs) with TiO2 nanoparticles as core and with poly(N,N-dimethylaminoethyl methacrylate-co-methyl methacrylate) by using triallylamine as cross-linking agent as shell were firstly prepared via atom transfer radical polymerization (ATRP) in methanol. Then the hybrid nanoparticles with positive charge were produced by the quaternization with methyl iodide as quaternization reagent so as to endow them with greater electrophoretic mobility. The cationic hybrid nanoparticles (TiO2-CHNPs) were studied by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS) measurements. The results indicate that the cationic polymer is successfully grafted on the surface of the TiO2 nanoparticles. The particle size of TiO2-CHNPs is about 150 nm and the polydispersity index (PDI) is 0.307. The zeta potential, the contrast ratio of white state to dark state and response time of TiO2-CHNPs are +16.8 mV, 30 and 3 s, respectively, which show the potential application prospect in the development of electrophoretic ink.

  11. 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.

  12. 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

  13. Relationship between the crystallization rates of amorphous nifedipine, phenobarbital, and flopropione, and their molecular mobility as measured by their enthalpy relaxation and (1)H NMR relaxation times.

    PubMed

    Aso, Y; Yoshioka, S; Kojima, S

    2000-03-01

    Isothermal crystallization of amorphous nifedipine, phenobarbital, and flopropione was studied at temperatures above and below their glass transition temperatures (T(g)). A sharp decrease in the crystallization rate with decreasing temperature was observed for phenobarbital and flopropione, such that no crystallization was observed at temperatures 20-30 degrees C lower than their T(g) within ordinary experimental time periods. In contrast, the crystallization rate of nifedipine decreased moderately with decreasing temperature, and considerable crystallization was observed at 40 degrees C below its T(g) within 4 months. The molecular mobility of these amorphous drugs was assessed by enthalpy relaxation and (1)H-NMR relaxation measurements. The enthalpy relaxation time of nifedipine was smaller than that of phenobarbital or flopropinone at the same T - T(g) values, suggesting higher molecular mobility of nifedipine. The spin-lattice relaxation time in the rotating frame (T(1rho)) decreased markedly at temperature above T(g). The slope of the Arrhenius type plot of the T(1rho) for nifedipine protons changed at about 10 degrees C below the T(g), whereas the slope for phenobarbital protons became discontinuous at about 10 degrees C above the T(g). Even at temperatures below its T(g), the spin-spin relaxation process of nifedipine could be described by the sum of its Gaussian relaxation, which is characteristic of solid protons, and its Lorentzian relaxation, which is characteristic of protons with higher mobility. In contrast, no Lorentzian relaxation was observed for phenobarbital or flopropione at temperatures below their T(g). These results also suggest that nifedipine has higher molecular mobility than phenobarbital and flopropione at temperatures below T(g). The faster crystallization of nifedipine than that of phenobarbital or flopropione observed at temperatures below its T(g) may be partly ascribed to its higher molecular mobility at these temperatures.

  14. 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

  15. 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.

  16. 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.

  17. Selectively-etched nanochannel electrophoretic and electrochemical devices

    DOEpatents

    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.

  18. 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.

  19. 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.

  20. Simulated null-gravity environments as applied to electrophoretic separations of biological species

    NASA Technical Reports Server (NTRS)

    Giannovario, J. A.; Griffin, R. N.

    1978-01-01

    The scale-up of electrophoretic separations to provide preparative quantities of materials has been hampered by gravity induced convection and sedimentation. The separation of biologically important species may be significantly enhanced by electrophoretic space processing. Simple demonstrations on past space flights have proven some principles. Several techniques have been evolved to study electrophoretic separations where the effects of gravity have been nullified or significantly reduced. These techniques employ mechanical design, density gradients and computer modeling. Utilization of these techniques for ground based studies will yield clues as to which biological species can be considered prime candidates for electrophoretic processing in zero-G.

  1. Quasielastic and electrophoretic light scattering studies of polyelectrolyte-micelle complexes

    NASA Astrophysics Data System (ADS)

    Rigsbee, Daniel R.; Dubin, Paul L.

    1991-06-01

    The aqueous system comprised of poly(dimethylammonium chloride) (a strongly cationic polymer) and a mixture of sodium dodecyl sulfate and Triton X-100 (anionic/nonionic mixed micelles) forms polyelectrolyte-micelle complexes. At suitable micelle compositions and ionic strengths, soluble complexes are formed, which may be studied by a variety of solution techniques, including quasielastic light scattering. In this report, the authors examine the influence of polymer molecular weight and micelle composition on the nature of these complexes. Multiangle measurements were made with two different instruments (hence different procedures for extracting apparent size distributions from measured autocorrelation curves). At the concentrations employed, multipolymer complexes appear to form. The QELS data, taken in conjunction with limited electrophoretic light scattering results, suggest that the main determinant of the extent of higher-order aggregation are those factors influencing the net charge of a 'primary' i.e. intrapolymer complex, with molecular weight per se playing a secondary role.

  2. 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.

  3. 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.

  4. NMR studies of metalloproteins.

    PubMed

    Li, Hongyan; Sun, Hongzhe

    2012-01-01

    Metalloproteins represent a large share of the proteomes, with the intrinsic metal ions providing catalytic, regulatory, and structural roles critical to protein functions. Structural characterization of metalloproteins and identification of metal coordination features including numbers and types of ligands and metal-ligand geometry, and mapping the structural and dynamic changes upon metal binding are significant for understanding biological functions of metalloproteins. NMR spectroscopy has long been used as an invaluable tool for structure and dynamic studies of macromolecules. Here we focus on the application of NMR spectroscopy in characterization of metalloproteins, including structural studies and identification of metal coordination spheres by hetero-/homo-nuclear metal NMR spectroscopy. Paramagnetic NMR as well as (13)C directly detected protonless NMR spectroscopy will also be addressed for application to paramagnetic metalloproteins. Moreover, these techniques offer great potential for studies of other non-metal binding macromolecules.

  5. SQUID detected NMR and MRI at ultralow fields

    SciTech Connect

    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.

  6. 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.

  7. Squid detected NMR and MRI at ultralow fields

    DOEpatents

    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.

  8. 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.

  9. Electrophoretic motion of ideally polarizable particles in a microchannel.

    PubMed

    Wu, Zhemin; Gao, Yandong; Li, Dongqing

    2009-03-01

    The induced-charge electrophoretic (ICEP) motion of ideally polarizable particles in a microchannel is numerically studied in this paper. A complete 3-D multi-physics model is set up to simulate the transient ICEP motion of spherical ideally polarizable particles in a microchannel. The study shows that a non-uniform distribution of induced surface charge occurs when an ideally polarizable particle is immersed in an externally applied electric field, resulting in a varying slipping (EOF) velocity along the particle's surface and hence producing micro vortexes in the liquid. The numerical results verify that the steady-state ICEP velocity of an ideally polarizable particle does not differ from the electrophoretic velocity of a non-conducting particle, although the flow field near the particle does. A strong wall-repelling effect of ICEP is found when the polarizable particle is placed close to the channel wall. This is due to the lifting effect generated from the interaction between the induced micro vortexes and the channel wall and depends on the electric field and the particle size. The wall effects on ICEP motion can be used for focusing particles and for separation of particle by density. PMID:19197897

  10. Electrophoretic analysis of PEGylated hemoglobin-based blood substitutes.

    PubMed

    Ronda, Luca; Pioselli, Barbara; Bruno, Stefano; Faggiano, Serena; Mozzarelli, Andrea

    2011-01-01

    Polyethylene glycol (PEG)-conjugated hemoglobins, a novel class of blood substitutes, were investigated by a combination of native and denaturing one- and two-dimensional polyacrylamide gel electrophoresis (PAGE) coupled with the microspectrophotometric characterization of single bands and the functional analysis of electrophoretically separated fractions. For these intrinsically heterogeneous products, the molecular mass, the size distribution, and the degree of PEGylation are strictly correlated to their side effects and, therefore, are crucial pieces of information to evaluate their safety and efficacy. The PEGylation pattern was shown to strongly depend on the quaternary conformation of hemoglobin during the reaction, and the degree of conjugation was shown to correlate with the oxygen binding properties of the individual electrophoretically separated fractions. Moreover, small but not negligible fractions of underivatized tetramers, known to be responsible for serious side effects, were detected even in preparations with a high average degree of PEGylation. Overall, this approach might be exploited to characterize other products of protein PEGylation, an increasingly relevant technology for the optimization of the pharmacokinetic properties of protein-based drugs.

  11. Recent innovations in protein separation on microchips by electrophoretic methods.

    PubMed

    Peng, Youyuan; Pallandre, Antoine; Tran, N Thuy; Taverna, Myriam

    2008-01-01

    Microchips for analytical purposes have attracted great attention over the last 20 years. In the present review, we focus on the most recent development of microchips for electrophoretic separation of proteins. This review starts with a short recalling about the microchips covering the basic microchip layout for CE and the commercial chips and microchip platforms. A short paragraph is dedicated to the surface treatment of microchips, which is of paramount importance in protein analysis. One section is dedicated to on-line sample pretreatment in microchips and summarizes different strategies to pre-concentrate or to purify proteins from complex matrixes. Most of the common modes used for CE of proteins have already been adapted to the chip format, while multidimensional approaches are still in progress. The different routes to achieve detection in microchip are also presented with a special attention to derivatization or labeling of proteins. Finally, several recent applications are mentioned. They highlight the great potential of electrophoretic separations of proteins in numerous fields such as biological, pharmaceutical or agricultural and food analysis. A bibliography with 151 references is provided covering papers published from 2000 to the early 2007.

  12. 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.

  13. 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%.

  14. 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.

  15. Single crystal to single crystal topochemical photoreactions: measuring the degree of disorder in the [2+2] photodimerization of trans-cinnamic acid using single-crystal 13C NMR spectroscopy.

    PubMed

    Nieuwendaal, Ryan C; Mattler, Sarah J; Bertmer, Marko; Hayes, Sophia E

    2011-05-19

    A single crystal of α-trans-cinnamic acid was synthesized with a (13)C-label at the β-carbon position and photoreacted to yield the [2+2] cycloaddition product, α-truxillic acid. (13)C{(1)H} cross-polarization (CP) single-crystal NMR experiments were performed on the unreacted and sequentially photoreacted samples for different goniometer orientations, and the spectra were simulated using the SIMMOL and SIMPSON software packages. Atomic coordinates from single-crystal X-ray diffraction data were used as inputs in the simulations, which allowed the chemical shift tensor to be precisely measured and related to the unit cell (or molecular) reference frame of cinnamic acid. The line widths of the (13)C resonances observed at different goniometer rotations were utilized to estimate the orientational dispersion of the cinnamic acid species, which ultimately provides a measure of disorder in the single crystal. The photoreacted sample, a solid solution of cinnamic and truxillic acids, maintained its single-crystal nature, even up to 44% conversion to truxillic acid, keeping its P2(1)/n symmetry. Upon photoirradiation, however, a slight loss of order was observed in the cinnamic acid species as evidenced by an increase in the (13)C NMR line widths, demonstrating that NMR can be used to monitor subtle orientational imperfections in single crystal to single crystal photoreactions.

  16. NMR methods in combinatorial chemistry.

    PubMed

    Shapiro, M J; Wareing, J R

    1998-06-01

    The use of NMR spectroscopy in combinatorial chemistry has provided a versatile tool for monitoring combinatorial chemistry reactions and for assessing ligand-receptor interactions. The application of magic angle spinning NMR is widespread and has allowed structure determination to be performed on compounds attached to solid supports. A variety of two-dimensional NMR techniques have been applied to enhance the usability of the magic angle spinning NMR data. New developments for solution NMR analysis include high performance liquid chromatography, NMR, mass spectroscopy and flow NMR. NMR based methods currently being investigated may prove valuable as compound screening tools.

  17. 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

  18. 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

  19. Demonstrating Electrophoretic Separation in a Straight Paper Channel Delimited by a Hydrophobic Wax Barrier

    ERIC Educational Resources Information Center

    Xu, Chunxiu; Lin, Wanqi; Cai, Longfei

    2016-01-01

    A demonstration is described of electrophoretic separation of carmine and sunset yellow with a paper-based device. The channel in the paper device was fabricated by hand with a wax pen. Electrophoretic separation of carmine and sunset yellow was achieved within a few minutes by applying potential on the channel using a simple and inexpensive power…

  20. On the sensitivity of running-fluid NMR magnetometers

    NASA Astrophysics Data System (ADS)

    Davydov, V. V.; Dudkin, V. I.; Petrov, A. A.; Myazin, N. S.

    2016-07-01

    A new procedure for determining the sensitivity of running-fluid NMR magnetometers is considered. The procedure is based on mathematical processing of experimental data that are related to measuring the gradient of a nutation-line slope at the point at which an inverted NMR signal crosses zero. The procedure allows one to determine the sensitivity of running-fluid NMR magnetometers for resonance frequencies of magnetic-field measurements within a range of 0.5 Hz to 840 MHz.

  1. 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

  2. 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.

  3. Relating chromatographic retention and electrophoretic mobility to the ion distribution within electrosprayed droplets.

    PubMed

    Bökman, C Fredrik; Bylund, Dan; Markides, Karin E; Sjöberg, Per J R

    2006-03-01

    Ions that are observed in a mass spectrum obtained with electrospray mass spectrometry can be assumed to originate preferentially from ions that have a high distribution to the surface of the charged droplets. In this study, a relation between chromatographic retention and electrophoretic mobility to the ion distribution (derived from measured signal intensities in mass spectra and electrospray current) within electrosprayed droplets for a series of tetraalkylammonium ions, ranging from tetramethyl to tetrapentyl, is presented. Chromatographic retention in a reversed-phase system was taken as a measure of the analyte's surface activity, which was found to have a large influence on the ion distribution within electrosprayed droplets. In addition, different transport mechanisms such as electrophoretic migration and diffusion can influence the surface partitioning coefficient. The viscosity of the solvent system is affected by the methanol content and will influence both diffusion and ion mobility. However, as diffusion and ion mobility are proportional to each other, we have, in this study, chosen to focus on the ion mobility parameter. It was found that the influence of ion mobility relative to surface activity on the droplet surface partitioning of analyte ions decreases with increasing methanol content. This effect is most probably coupled to the decrease in droplet size caused by the decreased surface tension at increasing methanol content. The same observation was made upon increasing the ionic strength of the solvent system, which is also known to give rise to a decreased initial droplet size. The observed effect of ionic strength on the droplet surface partitioning of analyte ions could also be explained by the fact that at higher ionic strength, a larger number of ions are initially closer to the droplet surface and, thus, the contribution of ionic transport from the bulk liquid to the liquid/air surface interface (jet and droplet surface), attributable to

  4. Pure shift NMR.

    PubMed

    Zangger, Klaus

    2015-04-01

    Although scalar-coupling provides important structural information, the resulting signal splittings significantly reduce the resolution of NMR spectra. Limited resolution is a particular problem in proton NMR experiments, resulting in part from the limited proton chemical shift range (∼10 ppm) but even more from the splittings due to scalar coupling to nearby protons. "Pure shift" NMR spectroscopy (also known as broadband homonuclear decoupling) has been developed for disentangling overlapped proton NMR spectra. The resulting spectra are considerably simplified as they consist of single lines, reminiscent of proton-decoupled C-13 spectra at natural abundance, with no multiplet structure. The different approaches to obtaining pure shift spectra are reviewed here and several applications presented. Pure shift spectra are especially useful for highly overlapped proton spectra, as found for example in reaction mixtures, natural products and biomacromolecules.

  5. 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.

  6. Separation of aracytidine and cytidine by capillary electrophoretic techniques.

    PubMed

    Krivánková, L; Kostálová, A; Vargas, G; Havel, J; Bocek, P

    1996-12-01

    Aracytidine (cytarabine, 1-beta-D-arabinofuranosylcytosine) is a synthetic analog of cytidine in which ribose is substituted by arabinose; it is used as a drug for the treatment of leukemia. A fast and reliable capillary electrophoretic method for the analysis of cytarabine and cytidine is described. The procedure utilizes the interactions with sodium dodecyl sulfate (SDS) micelles and borate, present in the background electrolyte, for the mobilization and selective separation of the analytes. The detection is carried out by UV absorbance at 275 nm. The method was applied both to pharmaceutical preparations and human serum. Analysis of an untreated serum requires 15 min; the detection limit is 0.8 microgram/mL and the relative standard deviation (RSD) is 5.3%.

  7. 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.

  8. Electrophoretic Deposition Applied to Thick Metal-Ceramic Coatings

    SciTech Connect

    Windes, William Enoch; Zimmerman, Jeramy; Reimanis, Ivar E.

    2002-08-01

    Electrophoretic deposition was used to fabricate thick (4 mm) metal–ceramic deposits from a non-aqueous slurry of nickel and alumina particles. A high solid volume in the slurry was identified as the primary parameter for depositing thick cermet coatings rather than the applied electric potential or ionic additive concentration. Ionic additives (MgCl2, AlCl3, etc.) were found to adequately suspend the alumina particles and provide rapid deposition rates. The nickel particles proved to be more difficult to suspend in solution, thereby sacrificing control of the deposition composition. The use of small (3.0 µm) particles and continuously pumping the slurry alleviated the suspension problems but small electric potentials (100 V/cm) were required to avoid the formation of rough, columnar deposits on the depositing electrode.

  9. 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.

  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. 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.

  12. Zirconia/alumina functionally gradiented composites by electrophoretic deposition techniques

    SciTech Connect

    Sarkar, P.; Huang, Xuening; Nicholson, P.S. . Dept. of Materials Science and Engineering)

    1993-04-01

    Continuous variation of composition, and thus of physical property, is characteristic of a functionally gradiented material (FGM). Such composite find applications in extreme thermal shielding, the joining of ceramics to metals, optical/electronic functions, and biomaterial implant development. FGMs have been synthesized by chemical vapor deposition (CVD), plasma spraying, self-propagating high-temperature synthesis, and green forming followed by sintering. An electrophoretic deposition and sintering route was used to prepare YSZ/Al[sub 2]O[sub 3] composites with a compositional gradient. The YSZ content was continuously decreased from the YSZ-rich surface to the Al[sub 2]O[sub 3]-rich surface. Microstructural and Vickers hardness (16--24 GPa) evidence tracked the compositional development, and the indentation fracture toughness was found to vary across the section (10--3 MPa[center dot]m[sup 1/2]).

  13. 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.

  14. Water buffalo (Bubalus bubalis) hemoglobins: an electrophoretic and chromatographic study.

    PubMed

    Di Luccia, A; Iannibelli, L; Ferranti, P; Iorio, M; Annunziata, M; Ferrara, L

    1989-01-01

    1. Hemoglobins from three phenotypes of Italian water buffalo (Bubalus bubalis), named AA, AB and BB, were selected by starch gel electrophoresis at alkaline pH and analyzed using polyacrylamide gel isoelectric focusing and subsequent analysis of titration curves to reveal differences between two types of hemoglobin identified as Hb fast and Hb slow. 2. Globins from Hb fast and Hb slow were purified by fast protein liquid chromatography (FPLC). Electrophoretic differences were found in the respective alpha-chains using polyacrylamide gel disc-electrophoresis at acid pH, polyacrylamide gel isoelectric focusing and by subsequently analyzing titration curves. 3. The results suggest that the alpha chains of Hb fast and Hb slow, called I alpha and II alpha, respectively, differ in at least two aminoacid residues. Subsequently, these amino acids were identified as lysine and cysteine.

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. 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.''

  1. 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.

  2. Multilocus Electrophoretic Assessment of the Genetic Structure and Diversity of Yersinia ruckeri

    PubMed Central

    Schill, William B.; Phelps, Stevan R.; Pyle, Stephen W.

    1984-01-01

    Multilocus isoenzyme electrophoresis was used to screen 47 field isolates of Yersinia ruckeri for electrophoretic variation at 15 enzyme loci. Only four electrophoretic types were observed, thus indicating that the genetic structure of Y. ruckeri is clonal. Forty-two isolates were of one electrophoretic type, a reflection of the low amount of genetic diversity extant in this species. Although sorbitol fermentation has been considered to be indicative of a second biotype, no significant gene frequency differences were found between the group of 20 isolates that readily used sorbitol as the sole carbon source and the group of 27 that did not. Images PMID:16346669

  3. 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

  4. 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.

  5. Direct Comparison of (19)F qNMR and (1)H qNMR by Characterizing Atorvastatin Calcium Content.

    PubMed

    Liu, Yang; Liu, Zhaoxia; Yang, Huaxin; He, Lan

    2016-01-01

    Quantitative nuclear magnetic resonance (qNMR) is a powerful tool in measuring drug content because of its high speed, sensitivity, and precision. Most of the reports were based on proton qNMR ((1)H qNMR) and only a few fluorine qNMR ((19)F qNMR) were reported. No research has been conducted to directly compare the advantage and disadvantage between these two methods. In the present study, both (19)F and (1)H qNMR were performed to characterize the content of atorvastatin calcium with the same internal standard. Linearity, precision, and results from two methods were compared. Results showed that (19)F qNMR has similar precision and sensitivity to (1)H qNMR. Both methods generate similar results compared to mass balance method. Major advantage from (19)F qNMR is that the analyte signal is with less or no interference from impurities. (19)F qNMR is an excellent approach to quantify fluorine-containing analytes. PMID:27688925

  6. Direct Comparison of 19F qNMR and 1H qNMR by Characterizing Atorvastatin Calcium Content

    PubMed Central

    Liu, Yang; Liu, Zhaoxia; Yang, Huaxin

    2016-01-01

    Quantitative nuclear magnetic resonance (qNMR) is a powerful tool in measuring drug content because of its high speed, sensitivity, and precision. Most of the reports were based on proton qNMR (1H qNMR) and only a few fluorine qNMR (19F qNMR) were reported. No research has been conducted to directly compare the advantage and disadvantage between these two methods. In the present study, both 19F and 1H qNMR were performed to characterize the content of atorvastatin calcium with the same internal standard. Linearity, precision, and results from two methods were compared. Results showed that 19F qNMR has similar precision and sensitivity to 1H qNMR. Both methods generate similar results compared to mass balance method. Major advantage from 19F qNMR is that the analyte signal is with less or no interference from impurities. 19F qNMR is an excellent approach to quantify fluorine-containing analytes. PMID:27688925

  7. Direct Comparison of 19F qNMR and 1H qNMR by Characterizing Atorvastatin Calcium Content

    PubMed Central

    Liu, Yang; Liu, Zhaoxia; Yang, Huaxin

    2016-01-01

    Quantitative nuclear magnetic resonance (qNMR) is a powerful tool in measuring drug content because of its high speed, sensitivity, and precision. Most of the reports were based on proton qNMR (1H qNMR) and only a few fluorine qNMR (19F qNMR) were reported. No research has been conducted to directly compare the advantage and disadvantage between these two methods. In the present study, both 19F and 1H qNMR were performed to characterize the content of atorvastatin calcium with the same internal standard. Linearity, precision, and results from two methods were compared. Results showed that 19F qNMR has similar precision and sensitivity to 1H qNMR. Both methods generate similar results compared to mass balance method. Major advantage from 19F qNMR is that the analyte signal is with less or no interference from impurities. 19F qNMR is an excellent approach to quantify fluorine-containing analytes.

  8. 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.

  9. Combined NMR-observation of cold denaturation in supercooled water and heat denaturation enables accurate measurement of deltaC(p) of protein unfolding.

    PubMed

    Szyperski, Thomas; Mills, Jeffrey L; Perl, Dieter; Balbach, Jochen

    2006-04-01

    Cold and heat denaturation of the double mutant Arg 3-->Glu/Leu 66-->Glu of cold shock protein Csp of Bacillus caldolyticus was monitored using 1D (1)H NMR spectroscopy in the temperature range from -12 degrees C in supercooled water up to +70 degrees C. The fraction of unfolded protein, f (u), was determined as a function of the temperature. The data characterizing the unfolding transitions could be consistently interpreted in the framework of two-state models: cold and heat denaturation temperatures were determined to be -11 degrees C and 39 degrees C, respectively. A joint fit to both cold and heat transition data enabled the accurate spectroscopic determination of the heat capacity difference between native and denatured state, DeltaC(p) of unfolding. The approach described in this letter, or a variant thereof, is generally applicable and promises to be of value for routine studies of protein folding.

  10. 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

  11. Electrophoretic and immunoblot analyses of Rhizopus arrhizus antigens.

    PubMed Central

    Wysong, D R; Waldorf, A R

    1987-01-01

    Four antigen preparations from Rhizopus arrhizus were made and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and column chromatography. Electrophoretic analyses of these antigens indicated that there are 18 to 28 component bands with a molecular mass range of approximately 10,500 to 83,000 daltons. Seven of these bands appear to be components common to three antigen preparations. Several of the bands identified by SDS-PAGE were composed of glycoproteins or carbohydrates as determined by their affinity for concanavalin A. Western blots, using sera from five patients with mucormycosis, consistently identified five different determinants in the R. arrhizus antigens separated by SDS-PAGE. This suggests that several of the Rhizopus antigens are present during mucormycosis. Four of the antigenic determinants recognized by patient sera reacted with the concanavalin A-peroxidase stain, indicating that they are composed of glycoproteins or carbohydrate. Enzyme-linked immunosorbent assays of sera from five patients with mucormycosis and with rabbit antisera resulted in antibody titers ranging from 1:64 to 1:32,000 for the R. arrhizus antigens. Images PMID:3546367

  12. Electrophoretic and immunoblot analyses of Rhizopus arrhizus antigens.

    PubMed

    Wysong, D R; Waldorf, A R

    1987-02-01

    Four antigen preparations from Rhizopus arrhizus were made and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and column chromatography. Electrophoretic analyses of these antigens indicated that there are 18 to 28 component bands with a molecular mass range of approximately 10,500 to 83,000 daltons. Seven of these bands appear to be components common to three antigen preparations. Several of the bands identified by SDS-PAGE were composed of glycoproteins or carbohydrates as determined by their affinity for concanavalin A. Western blots, using sera from five patients with mucormycosis, consistently identified five different determinants in the R. arrhizus antigens separated by SDS-PAGE. This suggests that several of the Rhizopus antigens are present during mucormycosis. Four of the antigenic determinants recognized by patient sera reacted with the concanavalin A-peroxidase stain, indicating that they are composed of glycoproteins or carbohydrate. Enzyme-linked immunosorbent assays of sera from five patients with mucormycosis and with rabbit antisera resulted in antibody titers ranging from 1:64 to 1:32,000 for the R. arrhizus antigens.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. Solution ripening of hydroxyapatite nanoparticles: effects on electrophoretic deposition.

    PubMed

    Wei, M; Ruys, A J; Milthorpe, B K; Sorrell, C C

    1999-04-01

    Electrophoretic deposition is a low-cost, simple, and flexible coating method for producing hydroxyapatite (Hap) coatings on metal implants. However, densification requires heating the coated metal to high temperatures, which, for commercial HAp powders, generally means at least 1200 degrees C. At such temperatures, the metal tends to react with the HAp coating, inducing decomposition, and the strength of titanium and stainless steel implants is severely degraded. With the use of raw uncalcined nanoparticulate Hap, densification can occur at 900 degrees -1050 degrees C; however, such coatings are prone to cracking due to the high drying shrinkage. This problem was solved by precipitating nanoparticulate HAp by the metathesis process [10Ca(NO3)2 + 6NH4H2PO4 + 8NH4OH] and optimizing the approximately 30 nm of nanoprecipitates by an Ostwald ripening approach, that is, by boiling and/or ambient aging in the mother liquor. While the as-precipitated nanoparticles produced severely cracked coatings, 2 h of boiling or 10 days of ambient aging ripened the "gel-like" mass into unagglomerated nanoparticles, which produced crack-free coatings. Since boiling enhanced particle size but ambient aging did not, crack elimination probably was due to the transition from the highly agglomerated gel-like state to the dispersed nanoparticulate state rather than to particle growth. Furthermore, boiling only reduced the amount of cracking whereas aging completely eliminated cracking.

  18. 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.

  19. Electrophoretic coating of amphiphilic chitosan colloids on regulating cellular behaviour.

    PubMed

    Wang, Yen-Jen; Lo, Teng-Yuan; Wu, Chieh-Hsi; Liu, Dean-Mo

    2013-09-01

    In this communication, we report a facile nanotopographical control over a stainless steel surface via an electrophoretic deposition of colloidal amphiphilic chitosan for preferential growth, proliferation or migration of vascular smooth muscle cells (VSMCs) and human umbilical vein endothelial cells (HUVECs). Atomic force microscopy revealed that the colloidal surface exhibited a deposition time-dependent nanotopographical evolution, wherein two different nanotopographic textures indexed by 'kurtosis' (Rkur) value were easily designed, which were termed as 'sharp' (i.e. high peak-to-valley texture) surface and 'flat' (i.e. low peak-to-valley texture) surface. Cellular behaviour of VSMCs and HUVECs on both surfaces demonstrated topographically dependent morphogenesis, adherent responses and biochemical properties in comparison with bare stainless steel. The formation of a biofunctionalized surface upon a facile colloidal chitosan deposition envisions the potential application towards numerous biomedical devices, and this is especially promising for cardiovascular stents wherein a new surface with optimized texture can be designed and is expected to create an advantageous environment to stimulate HUVEC growth for improved healing performance. PMID:23804439

  20. 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.

  1. 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

  2. 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.

  3. Pulsed-field gel electrophoretic analysis of leptospiral DNA.

    PubMed Central

    Taylor, K A; Barbour, A G; Thomas, D D

    1991-01-01

    The genomic structures of spirochete species are not well characterized, and genetic studies on these organisms have been hampered by lack of a genetic exchange mechanism in these bacteria. In view of these observations, pulsed-field gel electrophoresis was used to examine the genomes of Leptospira species. Live cells, prepared in agarose plugs, were lysed in situ, and the DNA was analyzed under different electrophoretic conditions. Pulsed-field gel electrophoresis of DNA digested with infrequently cutting restriction enzymes showed that the genome of Leptospira interrogans serovar canicola is approximately 3.1 Mb, while that of the saprophytic L. biflexa serovar patoc I is 3.5 Mb. DNA forms of approximately 2,000 and 350 kb which were present in samples from L. interrogans serovars were not readily detected in nonpathogenic serovars. Three distinct populations, designated type alpha, beta, and gamma, of L. interrogans DNA molecules were further analyzed with two-dimensional gel electrophoresis. Evidence suggested that two of these DNA forms, type alpha and gamma, were linear structures. Pulsed-field gel electrophoresis has proven to be a valuable tool with which to size bacterial genomes and to take the first steps toward characterization of a form of leptospiral DNA which behaves as a linear molecule and which may be related to the virulence of L. interrogans. Images PMID:1987046

  4. Fabrication of Electrophoretic Display Driven by Membrane Switch Array

    NASA Astrophysics Data System (ADS)

    Kazuo Senda,; Hiroaki Usui,

    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.

  5. 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

  6. 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.

  7. 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

  8. Electrophoretic coating of amphiphilic chitosan colloids on regulating cellular behaviour.

    PubMed

    Wang, Yen-Jen; Lo, Teng-Yuan; Wu, Chieh-Hsi; Liu, Dean-Mo

    2013-09-01

    In this communication, we report a facile nanotopographical control over a stainless steel surface via an electrophoretic deposition of colloidal amphiphilic chitosan for preferential growth, proliferation or migration of vascular smooth muscle cells (VSMCs) and human umbilical vein endothelial cells (HUVECs). Atomic force microscopy revealed that the colloidal surface exhibited a deposition time-dependent nanotopographical evolution, wherein two different nanotopographic textures indexed by 'kurtosis' (Rkur) value were easily designed, which were termed as 'sharp' (i.e. high peak-to-valley texture) surface and 'flat' (i.e. low peak-to-valley texture) surface. Cellular behaviour of VSMCs and HUVECs on both surfaces demonstrated topographically dependent morphogenesis, adherent responses and biochemical properties in comparison with bare stainless steel. The formation of a biofunctionalized surface upon a facile colloidal chitosan deposition envisions the potential application towards numerous biomedical devices, and this is especially promising for cardiovascular stents wherein a new surface with optimized texture can be designed and is expected to create an advantageous environment to stimulate HUVEC growth for improved healing performance.

  9. Electrophoretic mobility of supercoiled, catenated and knotted DNA molecules

    PubMed Central

    Cebrián, Jorge; Kadomatsu-Hermosa, Maridian J.; Castán, Alicia; Martínez, Víctor; Parra, Cristina; Fernández-Nestosa, María José; Schaerer, Christian; Martínez-Robles, María-Luisa; Hernández, Pablo; Krimer, Dora B.; Stasiak, Andrzej; Schvartzman, Jorge B.

    2015-01-01

    We systematically varied conditions of two-dimensional (2D) agarose gel electrophoresis to optimize separation of DNA topoisomers that differ either by the extent of knotting, the extent of catenation or the extent of supercoiling. To this aim we compared electrophoretic behavior of three different families of DNA topoisomers: (i) supercoiled DNA molecules, where supercoiling covered the range extending from covalently closed relaxed up to naturally supercoiled DNA molecules; (ii) postreplicative catenanes with catenation number increasing from 1 to ∼15, where both catenated rings were nicked; (iii) knotted but nicked DNA molecules with a naturally arising spectrum of knots. For better comparison, we studied topoisomer families where each member had the same total molecular mass. For knotted and supercoiled molecules, we analyzed dimeric plasmids whereas catenanes were composed of monomeric forms of the same plasmid. We observed that catenated, knotted and supercoiled families of topoisomers showed different reactions to changes of agarose concentration and voltage during electrophoresis. These differences permitted us to optimize conditions for their separation and shed light on physical characteristics of these different types of DNA topoisomers during electrophoresis. PMID:25414338

  10. An improved driving waveform reference grayscale of electrophoretic displays

    NASA Astrophysics Data System (ADS)

    Wang, Li; Yi, Zichuan; Peng, Bao; Zhou, Guofu

    2015-10-01

    Driving waveform is an important component for gray scale display on the electrophoretic display (EPD). In the traditional driving waveform, a white reference gray scale is formed before writing a new image. However, the reflectance value can not reach agreement in each gray scale transformation. In this paper, a new driving waveform, which has a short waiting time after the formation of reference gray scale, is proposed to improve the consistency of reference gray scale. Firstly, the property of the particles in the microcapsule is analyzed and the change of the EPD reflectance after the white reference gray scale formation is studied. Secondly, the reflectance change curve is fitted by using polynomial and the duration of the waiting time is determined. Thirdly, a set of the new driving waveform is designed by using the rule of DC balance and some real E-ink commercial EPDs are used to test the performance. Experimental results show that the effect of the new driving waveform has a better performance than traditional waveforms.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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.

  18. Draft Genome Sequences of Eight Nontypeable Haemophilus influenzae Strains Previously Characterized Using an Electrophoretic Typing Scheme

    PubMed Central

    Mussa, Huda J.; VanWagoner, Timothy M.; Seale, Thomas W.; Whitby, Paul W.; Stull, Terrence L.

    2015-01-01

    Nontypeable Haemophilus influenzae is an important cause of human disease. Strains were selected for genome sequencing to represent the breadth of nontypeable strains within the species, as previously defined by the electrophoretic mobility of 16 metabolic enzymes. PMID:26607889

  19. 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.

  20. 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.

  1. An Electrophoretic Analysis of the Isozymes of Malate Dehydrogenase in Several Different Plants 1

    PubMed Central

    Weimberg, Ralph

    1968-01-01

    The particulate and soluble fractions of cell-free extracts from seeds, roots, and leaves of 10 different plants were examined electrophoretically for isozymes of malate dehydrogenase. Distinct isozyme patterns were observed for each plant and even for the individual tissues of each species. There were some isozymes in several different plant extracts with equal electrophoretic mobilities, but there was no isozyme band that was common to all tissues or to all plants. Images PMID:16656816

  2. 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.

  3. 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.

  4. 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…

  5. Comparison of experimental vision performance testing techniques, including the implementation of an active matrix electrophoretic ink display

    NASA Astrophysics Data System (ADS)

    Swinney, Mathew W.; Marasco, Peter L.; Heft, Eric L.

    2007-04-01

    Standard black and white printed targets have been used for numerous vision related experiments, and are ideal with respect to contrast and spectral uniformity in the visible and near-infrared (NIR) regions of the electromagnetic (EM) spectrum. However, these targets lack the ability to refresh, update, or perform as a real-time, dynamic stimulus. This impacts their ability to be used in various standard vision performance measurement techniques. Emissive displays, such as a LCD's, possess some of the attributes printed targets lack, but come with a disadvantage of their own: LCD's lack the spectral uniformity of printed targets, making them of debatable value for presenting test targets in the near and short wave infrared regions of the spectrum. Yet a new option has recently become viable that may retain favorable attributes of both of the previously mentioned alternatives. The electrophoretic ink display is a dynamic, refreshable, and easily manipulated display that performs much like printed targets with respect to spectral uniformity. This paper will compare and contrast the various techniques that can be used to measure observer visual performance through night vision devices and imagers - focusing on the visible to infrared region of the EM spectrum. Furthermore, it will quantify the electrophoretic ink display option, determining its advantages and situations that it would be best suited for.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. NMR methodologies in the analysis of blueberries.

    PubMed

    Capitani, Donatella; Sobolev, Anatoly P; Delfini, Maurizio; Vista, Silvia; Antiochia, Riccarda; Proietti, Noemi; Bubici, Salvatore; Ferrante, Gianni; Carradori, Simone; De Salvador, Flavio Roberto; Mannina, Luisa

    2014-06-01

    An NMR analytical protocol based on complementary high and low field measurements is proposed for blueberry characterization. Untargeted NMR metabolite profiling of blueberries aqueous and organic extracts as well as targeted NMR analysis focused on anthocyanins and other phenols are reported. Bligh-Dyer and microwave-assisted extractions were carried out and compared showing a better recovery of lipidic fraction in the case of microwave procedure. Water-soluble metabolites belonging to different classes such as sugars, amino acids, organic acids, and phenolic compounds, as well as metabolites soluble in organic solvent such as triglycerides, sterols, and fatty acids, were identified. Five anthocyanins (malvidin-3-glucoside, malvidin-3-galactoside, delphinidin-3-glucoside, delphinidin-3-galactoside, and petunidin-3-glucoside) and 3-O-α-l-rhamnopyranosyl quercetin were identified in solid phase extract. The water status of fresh and withered blueberries was monitored by portable NMR and fast-field cycling NMR. (1) H depth profiles, T2 transverse relaxation times and dispersion profiles were found to be sensitive to the withering.

  12. 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

  13. Electrophoretic deposition of antibiotic loaded PHBV microsphere-alginate composite coating with controlled delivery potential.

    PubMed

    Chen, Qiang; Li, Wei; Goudouri, Ourania-Menti; Ding, Yaping; Cabanas-Polo, Sandra; Boccaccini, Aldo R

    2015-06-01

    Electrophoretic deposition (EPD) technique has been developed for the fabrication of antibiotic-loaded PHBV microsphere (MS)-alginate antibacterial coatings. The composite coatings deposited from suspensions with different MS concentrations were produced in order to demonstrate the versatility of the proposed method for achieving functional coatings with tailored drug loading and release profiles. Linearly increased deposit mass with increasing MS concentrations was obtained, and MS were found to be homogeneously stabilized in the alginate matrix. Chemical composition, surface roughness and wettability of the deposited coatings were measured by Fourier transform infrared (FTIR) spectroscopy, laser profilometer and water contact angle instruments, respectively. The co-deposition mechanism was described by two separate processes according to the results of relevant measurements: (i) the deposition of alginate-adsorbed MS and (ii) the non-adsorbed alginate. Qualitative antibacterial tests indicated that MS containing coatings exhibit excellent inhibition effects against E. coli (gram-negative bacteria) after 1h of incubation. The proposed coating system combined with the simplicity of the EPD technique can be considered a promising surface modification approach for the controlled in situ delivery of drug or other biomolecules.

  14. Electrophoretic deposition of antibiotic loaded PHBV microsphere-alginate composite coating with controlled delivery potential.

    PubMed

    Chen, Qiang; Li, Wei; Goudouri, Ourania-Menti; Ding, Yaping; Cabanas-Polo, Sandra; Boccaccini, Aldo R

    2015-06-01

    Electrophoretic deposition (EPD) technique has been developed for the fabrication of antibiotic-loaded PHBV microsphere (MS)-alginate antibacterial coatings. The composite coatings deposited from suspensions with different MS concentrations were produced in order to demonstrate the versatility of the proposed method for achieving functional coatings with tailored drug loading and release profiles. Linearly increased deposit mass with increasing MS concentrations was obtained, and MS were found to be homogeneously stabilized in the alginate matrix. Chemical composition, surface roughness and wettability of the deposited coatings were measured by Fourier transform infrared (FTIR) spectroscopy, laser profilometer and water contact angle instruments, respectively. The co-deposition mechanism was described by two separate processes according to the results of relevant measurements: (i) the deposition of alginate-adsorbed MS and (ii) the non-adsorbed alginate. Qualitative antibacterial tests indicated that MS containing coatings exhibit excellent inhibition effects against E. coli (gram-negative bacteria) after 1h of incubation. The proposed coating system combined with the simplicity of the EPD technique can be considered a promising surface modification approach for the controlled in situ delivery of drug or other biomolecules. PMID:25921640

  15. NMR in a Diamond Anvil Pressure Cell

    NASA Astrophysics Data System (ADS)

    Lawson, Matthew; Dioguardi, Adam; Weir, Samuel; Bush, Blaine; Dunuwille, Mihindra; Deemyad, Shanti; Curro, Nichlas

    We present recent advances in the use of diamond anvil pressure cells in nuclear magnetic resonance measurements. This technique allows access to new regions of the phase diagrams of iron pnictide and heavy fermion materials, and promises to allow NMR experiments under pressures not previously accessible.

  16. NMR phase noise in bitter magnets.

    PubMed

    Sigmund, E E; Calder, E S; Thomas, G W; Mitrović, V F; Bachman, H N; Halperin, W P; Kuhns, P L; Reyes, A P

    2001-02-01

    We have studied the temporal instability of a high field resistive Bitter magnet through nuclear magnetic resonance (NMR). This instability leads to transverse spin decoherence in repeated and accumulated NMR experiments as is normally performed during signal averaging. We demonstrate this effect via Hahn echo and Carr--Purcell--Meiboom--Gill (CPMG) transverse relaxation experiments in a 23-T resistive magnet. Quantitative analysis was found to be consistent with separate measurements of the magnetic field frequency fluctuation spectrum, as well as with independent NMR experiments performed in a magnetic field with a controlled instability. Finally, the CPMG sequence with short pulse delays is shown to be successful in recovering the intrinsic spin--spin relaxation even in the presence of magnetic field temporal instability.

  17. 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.

  18. Electrophoretic analysis of multiple forms of myosin in fast-twitch and slow-twitch muscles of the chick.

    PubMed Central

    Hoh, J Y; McGrath, P A; White, R I

    1976-01-01

    1. A method is described for the electrophoretic analysis of intact myosin in polyacrylamide gel in a buffer system containing 0.02 M-pyrophosphate and 10% (v/v) glycerol, pH 8.8. 2. In this system chicken skeletal-muscle myosins reveal five distinct electrophoretic components, three components from the fast-twitch posterior latissimus dorsi muscle and two slower-migrating components from the slow-twitch anterior latissimus dorsi muscle. 3. The Ca2+-activated ATPase (adenosine triphosphatase) activity of myosin components was measured by densitometric scanning of the gel for the Ca3(PO4)2 precipitate formed during the ATPase reaction and subsequently for stained protein. Each component from the same muscle appears to have identical ATPase activity, but components from the fast-twitch muscle had an activity 2.2 times higher than those from the slow-twitch muscle. 4. On re-electrophoresis in the same buffer system, individual fractions of fast-twitch myosin did not reproduce the three-band pattern of the original myosin, but migrated at rates consistent with their original mobility. 5. Analysis of the mobility of the three fast-twitch myosin components in gels of different concentrations suggests that they are not stable oligomers of each other. 6. It is suggested that these components of fast-twitch myosin and slow-twitch myosin are isoenzymes of myosin. PMID:183747

  19. 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

  20. Live cell NMR.

    PubMed

    Freedberg, Darón I; Selenko, Philipp

    2014-01-01

    Ever since scientists realized that cells are the basic building blocks of all life, they have been developing tools to look inside them to reveal the architectures and mechanisms that define their biological functions. Whereas "looking into cells" is typically said in reference to optical microscopy, high-resolution in-cell and on-cell nuclear magnetic resonance (NMR) spectroscopy is a powerful method that offers exciting new possibilities for structural and functional studies in and on live cells. In contrast to conventional imaging techniques, in- and on-cell NMR methods do not provide spatial information on cellular biomolecules. Instead, they enable atomic-resolution insights into the native cell states of proteins, nucleic acids, glycans, and lipids. Here we review recent advances and developments in both fields and discuss emerging concepts that have been delineated with these methods.

  1. 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.

  2. Enzyme dynamics from NMR spectroscopy.

    PubMed

    Palmer, Arthur G

    2015-02-17

    CONSPECTUS: Biological activities of enzymes, including regulation or coordination of mechanistic stages preceding or following the chemical step, may depend upon kinetic or equilibrium changes in protein conformations. Exchange of more open or flexible conformational states with more closed or constrained states can influence inhibition, allosteric regulation, substrate recognition, formation of the Michaelis complex, side reactions, and product release. NMR spectroscopy has long been applied to the study of conformational dynamic processes in enzymes because these phenomena can be characterized over multiple time scales with atomic site resolution. Laboratory-frame spin-relaxation measurements, sensitive to reorientational motions on picosecond-nanosecond time scales, and rotating-frame relaxation-dispersion measurements, sensitive to chemical exchange processes on microsecond-millisecond time scales, provide information on both conformational distributions and kinetics. This Account reviews NMR spin relaxation studies of the enzymes ribonuclease HI from mesophilic (Escherichia coli) and thermophilic (Thermus thermophilus) bacteria, E. coli AlkB, and Saccharomyces cerevisiae triosephosphate isomerase to illustrate the contributions of conformational flexibility and dynamics to diverse steps in enzyme mechanism. Spin relaxation measurements and molecular dynamics (MD) simulations of the bacterial ribonuclease H enzymes show that the handle region, one of three loop regions that interact with substrates, interconverts between two conformations. Comparison of these conformations with the structure of the complex between Homo sapiens ribonuclease H and a DNA:RNA substrate suggests that the more closed state is inhibitory to binding. The large population of the closed conformation in T. thermophilus ribonuclease H contributes to the increased Michaelis constant compared with the E. coli enzyme. NMR spin relaxation and fluorescence spectroscopy have characterized a

  3. Enzyme Dynamics from NMR Spectroscopy

    PubMed Central

    2016-01-01

    Conspectus Biological activities of enzymes, including regulation or coordination of mechanistic stages preceding or following the chemical step, may depend upon kinetic or equilibrium changes in protein conformations. Exchange of more open or flexible conformational states with more closed or constrained states can influence inhibition, allosteric regulation, substrate recognition, formation of the Michaelis complex, side reactions, and product release. NMR spectroscopy has long been applied to the study of conformational dynamic processes in enzymes because these phenomena can be characterized over multiple time scales with atomic site resolution. Laboratory-frame spin-relaxation measurements, sensitive to reorientational motions on picosecond–nanosecond time scales, and rotating-frame relaxation-dispersion measurements, sensitive to chemical exchange processes on microsecond–millisecond time scales, provide information on both conformational distributions and kinetics. This Account reviews NMR spin relaxation studies of the enzymes ribonuclease HI from mesophilic (Escherichia coli) and thermophilic (Thermus thermophilus) bacteria, E. coli AlkB, and Saccharomyces cerevisiae triosephosphate isomerase to illustrate the contributions of conformational flexibility and dynamics to diverse steps in enzyme mechanism. Spin relaxation measurements and molecular dynamics (MD) simulations of the bacterial ribonuclease H enzymes show that the handle region, one of three loop regions that interact with substrates, interconverts between two conformations. Comparison of these conformations with the structure of the complex between Homo sapiens ribonuclease H and a DNA:RNA substrate suggests that the more closed state is inhibitory to binding. The large population of the closed conformation in T. thermophilus ribonuclease H contributes to the increased Michaelis constant compared with the E. coli enzyme. NMR spin relaxation and fluorescence spectroscopy have characterized a

  4. Picoliter 1H NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Minard, Kevin R.; Wind, Robert A.

    2002-02-01

    In this study, a 267-μm-diameter solenoid transceiver is used to acquire localized 1H NMR spectra and the measured signal-to-noise ratio (SNR) at 500 MHz is shown to be within 20-30% of theoretical limits formulated by considering only its resistive losses. This is illustrated using a 100-μm-diameter globule of triacylglycerols (∼900 mM) that may be an oocyte precursor in young Xenopus laevis frogs and a water sample containing choline at a concentration often found in live mammalian cells (∼33 mM). In chemical shift imaging (CSI) experiments performed using a few thousand total scans, the choline methyl line is shown to have an acceptable SNR in resolved volume elements containing only 50 pL of sample, and localized spectra are resolved from just 5 pL in the Xenopus globule. These findings demonstrate the feasibility of performing 1H NMR on picoliter-scale sample volumes in biological cells and tissues and illustrate how the achieved SNR in spectroscopic images can be predicted with reasonable accuracy at microscopic spatial resolutions.

  5. 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

  6. 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

  7. 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.

  8. Intact protein separation by chromatographic and/or electrophoretic techniques for top-down proteomics.

    PubMed

    Capriotti, Anna Laura; Cavaliere, Chiara; Foglia, Patrizia; Samperi, Roberto; Laganà, Aldo

    2011-12-01

    Mass spectrometry used in combination with a wide variety of separation methods is the principal methodology for proteomics. In bottom-up approach, proteins are cleaved with a specific proteolytic enzyme, followed by peptide separation and MS identification. In top-down approach intact proteins are introduced into the mass spectrometer. The ions generated by electrospray ionization are then subjected to gas-phase separation, fragmentation, fragment separation, and automated interpretation of mass spectrometric and chromatographic data yielding both the molecular weight of the intact protein and the protein fragmentation pattern. This approach requires high accuracy mass measurement analysers capable of separating the multi-charged isotopic cluster of proteins, such as hybrid ion trap-Fourier transform instruments (LTQ-FTICR, LTQ-Orbitrap). Front-end separation technologies tailored for proteins are of primary importance to implement top-down proteomics. This review intends to provide the state of art of protein chromatographic and electrophoretic separation methods suitable for MS coupling, and to illustrate both monodimensional and multidimensional approaches used for LC-MS top-down proteomics. In addition, some recent progresses in protein chromatography that may provide an alternative to those currently employed are also discussed.

  9. Corrosion behaviour and bioactivity of electrophoretically deposited hydroxyapatite on titanium in physiological media (Hanks' solution)

    NASA Astrophysics Data System (ADS)

    Mohamed, S. G.; Abdeltawab, A. A.; Shoeib, M. A.

    2012-09-01

    Hydroxyapatite (HA) coatings were developed on titanium by electrophoretic deposition at various deposition potentials from 30 to 60 V and at a constant deposition time of 5 minutes using the synthetic HA (Ca10(PO4)6(OH)2,) powder in a suspension of dimethyleformamide (DMF, HCON(CH3)2). The electrochemical corrosion behavior of the HA coatings in simulated body fluid (SBF Hanks' solution) at 37 °C and pH 7.4 was investigated by means of open-circuit potential (OCP) measurement and potentiodynamic polarization tests. The OCP test showed that the values OCP for the coated samples shifted to more noble potential than for uncoated titanium, especially after addition of dispersants. The polarization test revealed that all HA coated specimens had a corrosion resistance higher than that of the substrate, especially after addition of dispersants such as polyvinyl butyral (PVB), polyethylene glycol (PEG) and triethanolamine (TEA) to the suspension. The coating morphology after polarization, characterized by scanning electron microscopy (SEM), showed penetration of electrolyte into the HA coats. Bone bioactivity of the coatings was also studied by immersion of coated specimens in Hanks' solution for 3 and 7 days. Apatite granules growth on the surface of the HA layers was observed.

  10. 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.

  11. Carboxylated ficolls: preparation, characterization, and electrophoretic behavior of model charged nanospheres.

    PubMed

    Guo, Xuhong; Kirton, Gavin F; Dubin, Paul L

    2006-10-26

    Carboxylated ficolls were prepared as model spherical colloids of variable charge and size, with radii ranging from 3.0 to 19.3 nm. Capillary electrophoresis (CE), electrophoretic light scattering (ELS), and potentiometric titration were used to determine mobilities as a function of pH, degree of ionization alpha, and surface potential psi(0). Measured mobilities typically display a plateau at high pH, corresponding to high alpha and psi(0), confirming the general nature of this effect for charged spheres, seen also for charged dendrimers and charged latex particles. This result is examined in the context of a discontinuity in mobility predicted by the Wiersema, O'Brien, and White (WOW) theory and a more recent primitive model electrophoresis (PME) theory, in which bound counterions are considered either as point charges or as hard spheres. While no mobility maximum can be determined as expected by these two theories, our data seem more to support Belloni's theoretical expectations on charged polymers and spheres. Here we explain the mobility plateaus in terms of counterions accumulated close to the surface (surface potential-determining ions) or within the shear plane (mobility-determining ions).

  12. Qualification of a microfluidics-based electrophoretic method for impurity testing of monoclonal antibodies.

    PubMed

    Antes, Bernhard; Oberkleiner, Philipp; Nechansky, Andreas; Szolar, Oliver H J

    2010-02-01

    In this work, we present a comprehensive evaluation of the Agilent Bioanalyzer, a microfluidics-based electrophoretic device that was used for impurity testing of a monoclonal antibody (mAb). We compared the system to SDS-PAGE, both operated under non-reducing conditions and found a significant improvement of accuracy for the Bioanalyzer. In addition, the latter exhibited a larger assay range and lower limit of quantitation (LOQ) based on a predefined total error limit of +/-30%. However, during method qualification applying a three-factor nested design with two operators performing duplicate measurements per day, each on 4 different days, we observed unpredictable recurring quantitative outliers using the chip-based system. In-depth analysis on multiple runs with various chip lots confirmed the above finding and indicated that most likely on-chip dye labeling and/or post-column background fluorescence elimination are not compatible with the large size of the intact antibody as similar findings were observed for myosin used as upper marker for time correction. Interestingly, after reducing the intact antibody into light and heavy chain, we resolved the outlier issue. Eventually, requalification of the micro-fabricated analytical device under reducing conditions revealed only 1 out of 32 quality control samples (QCs) exceeding the +/-30% total error limits.

  13. A thin porous substrate using bonded particles for reverse-emulsion electrophoretic displays

    NASA Astrophysics Data System (ADS)

    Ahumada, M.; Bryning, M.; Cromer, R.; Hartono, M.; Lee, S. J.

    2012-03-01

    A thin porous layer of bonded ceramic microparticles has been developed to provide structural integrity and a stationary matrix for use in reflective-mode reverse-emulsion electrophoretic displays (REED), based on self-assembled nanodroplets dispersed in a non-polar liquid. REED ink uses low-cost materials and manufacturing processes, yet is capable of video speed and low voltage operation below 10 V. Porous layers of titanium dioxide (TiO2) are prepared as thin as 10 microns by fluidizing the particles in a water-based slurry with polymeric adhesive. The slurry is distributed between glass shear plates, one of which serves as the substrate for the working device. Particle morphology is examined using scanning electron microscopy and layer uniformity is characterized by opacity measurements using a throughbeam fiber optic sensor. Performance of the bonded matrix with REED ink is compared to baseline performance of a paste mixture, comprised of the same ink and unbonded TiO2 particles. Results show that at 25% volume fraction, the bonded substrate improves image bistability and is better able to maintain both light and dark intensity after extensive switching. The same bonded substrate also improves image bistability when power is disconnected, even compared to a paste with 40% volume fraction of TiO2.

  14. 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.

  15. Synthesis of functionally graded materials via electrophoretic deposition and sintering

    NASA Astrophysics Data System (ADS)

    Wang, Xuan

    In this research, both the experiments and the modeling aspects of the net-shape fabrication of Functionally Graded Materials (FGM) by Electrophoretic Deposition (EPD) and consecutive sintering have been investigated. In order to obtain FGMs with desired final shape and properties, the issues regarding the shape evolution during sintering, the optimization of initial properties and composition profiles, and the fabrication of green components by EPD have been analyzed. In order to fabricate FGMs by the proposed technological sequence (EPD with the following sintering), the initial shape has to be optimized prior to sintering. In this research, the formulations to simulate sintering of an FGM were developed based on the continuum theory of sintering. A finite element sintering-modeling subroutine has been created and linked to the commercial finite element package ABAQUS. The shape changes of FGM disks during sintering were simulated. In order to obtain the desired final shape after sintering, an inverse modeling methodology was developed to optimize the initial shape. In order to fabricate the optimized initial shape of a green FGM specimen determined by the inverse continuum modeling of sintering, EPD of a number of FGMs was investigated. The FGM green specimens made of Al2O 3 and ZrO2 with the initial shape predicted by the inverse modeling, were deposited using self-designed equipments. The acetone-based suspension with n-butylamine as a particle-charging additive was used. The comparison of the shape between the sintered and the green FGM indicated that the developed experimental-theoretical methodology provided a reliable solution for near net shaping of complex 3-D FGM components. Other applications of EPD, such as in electronic packaging materials and zeolites, were also investigated. In order to fabricate functionally graded materials based on aligned porous structures, unidirectional freezing followed by freeze-drying and sintering has been investigated

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Dielectrophoretic and electrophoretic force analysis of colloidal fullerenes in a nematic liquid-crystal medium.

    PubMed

    Srivastava, Anoop Kumar; Kim, Miyoung; Kim, Sung Min; Kim, Mi-Kyung; Lee, Kyu; Lee, Young Hee; Lee, Myong-Hoon; Lee, Seung Hee

    2009-11-01

    This research focuses on the electrokinetic motion of fullerenes suspended in liquid crystal host medium, which are investigated in the homogeneously aligned nematic liquid crystal cells driven by in-plane field. We investigated the effect of electrophoretic and dielectrophoretic forces and related parameters of the colloidal fullerenes in liquid crystals. The electrophoretic mobility, zeta potential, and critical voltage have been evaluated. Fullerenes suspended in liquid crystal medium migrated toward the positive electrode, but were pulled back in the opposite direction when the polarity was reversed especially at low frequency range (<5 Hz) . At higher electric field and higher frequency ranges, the net displacement of fullerenes has been observed. We demonstrate that the dielectrophoretic force dominated the motion in the colloidal fullerenes by a proper analysis of different electrophoretic parameters. In addition, the electrodynamics of fullerenes was explained by applying the theory of the dielectrophoresis and Schwarz's formula. We propose a model to estimate the density of fullerenes suspended in liquid crystal medium.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. Spectroscopic characterization of coumarin-stained beads: quantification of the number of fluorophores per particle with solid-state 19F-NMR and measurement of absolute fluorescence quantum yields.

    PubMed

    Huber, Alexandra; Behnke, Thomas; Würth, Christian; Jaeger, Christian; Resch-Genger, Ute

    2012-04-17

    The rational design of nano- and micrometer-sized particles with tailor-made optical properties for biological, diagnostic, and photonic applications requires tools to characterize the signal-relevant properties of these typically scattering bead suspensions. This includes methods for the preferably nondestructive quantification of the number of fluorophores per particle and the measurement of absolute fluorescence quantum yields and absorption coefficients of suspensions of fluorescent beads for material performance optimization and comparison. Here, as a first proof-of-concept, we present the first time determination of the number of dye molecules per bead using nondestructive quantitative ((19)F) NMR spectroscopy and 1000 nm-sized carboxylated polystyrene particles loaded with varying concentrations of the laser dye coumarin 153 containing a CF(3) group. Additionally, the signal-relevant optical properties of these dye-loaded particles were determined in aqueous suspension in comparison to the free dye in solvents of different polarity with a custom-built integrating sphere setup that enables spectrally resolved measurements of emission, transmission, and reflectance as well absolute fluorescence quantum yields. These measurements present an important step toward absolute brightness values and quantitative fluorescence analysis with particle systems that can be exploited, for example, for optical imaging techniques and different fluorescence assays as well as for the metrological traceability of fluorescence methods. PMID:22404690

  11. 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.

  12. Distance measurements in disodium ATP hydrates by means of 31P double quantum two-dimensional solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Potrzebowski, M. J.; Gajda, J.; Ciesielski, W.; Montesinos, I. M.

    2006-04-01

    POST-C7 measurements provide constraints allowing distinguishing crystal lattice organization and establishing intra and/or intermolecular distances between phosphorus atoms of triphosphate chains for different hydrates of disodium ATP salts. Double-quantum efficiency in function of excitation time obtained from series of two-dimensional spectra for POST-C7 experiments was used to set up of buildup curves and semi-quantitative measure of 31P- 31P length.

  13. NMR blood vessel imaging method and apparatus

    SciTech Connect

    Riederer, S.J.

    1988-04-26

    A high speed method of forming computed images of blood vessels based on measurements of characteristics of a body is described comprising the steps of: subjecting a predetermined body area containing blood vessels of interest to, successively, applications of a short repetition time (TR) NMR pulse sequence during the period of high blood velocity and then to corresponding applications during the period of low blood velocity for successive heart beat cycles; weighting the collected imaging data from each application of the NMR pulse sequence according to whether the data was acquired during the period of high blood velocity or a period of low blood velocity of the corresponding heart beat cycle; accumulating weighted imaging data from a plurality of NMR pulse sequences corresponding to high blood velocity periods and from a plurality of NMR pulse sequences corresponding to low blood velocity periods; subtracting the weighted imaging data corresponding to each specific phase encoding acquired during the high blood velocity periods from the weighted imaging data for the same phase encoding corresponding to low blood velocity periods in order to compute blood vessel imaging data; and forming an image of the blood vessels of interest from the blood vessel imaging data.

  14. 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.

  15. Solid-state NMR structures of integral membrane proteins.

    PubMed

    Patching, Simon G

    2015-01-01

    Solid-state NMR is unique for its ability to obtain three-dimensional structures and to measure atomic-resolution structural and dynamic information for membrane proteins in native lipid bilayers. An increasing number and complexity of integral membrane protein structures have been determined by solid-state NMR using two main methods. Oriented sample solid-state NMR uses macroscopically aligned lipid bilayers to obtain orientational restraints that define secondary structure and global fold of embedded peptides and proteins and their orientation and topology in lipid bilayers. Magic angle spinning (MAS) solid-state NMR uses unoriented rapidly spinning samples to obtain distance and torsion angle restraints that define tertiary structure and helix packing arrangements. Details of all current protein structures are described, highlighting developments in experimental strategy and other technological advancements. Some structures originate from combining solid- and solution-state NMR information and some have used solid-state NMR to refine X-ray crystal structures. Solid-state NMR has also validated the structures of proteins determined in different membrane mimetics by solution-state NMR and X-ray crystallography and is therefore complementary to other structural biology techniques. By continuing efforts in identifying membrane protein targets and developing expression, isotope labelling and sample preparation strategies, probe technology, NMR experiments, calculation and modelling methods and combination with other techniques, it should be feasible to determine the structures of many more membrane proteins of biological and biomedical importance using solid-state NMR. This will provide three-dimensional structures and atomic-resolution structural information for characterising ligand and drug interactions, dynamics and molecular mechanisms of membrane proteins under physiological lipid bilayer conditions.

  16. Solid-state NMR structures of integral membrane proteins.

    PubMed

    Patching, Simon G

    2015-01-01

    Solid-state NMR is unique for its ability to obtain three-dimensional structures and to measure atomic-resolution structural and dynamic information for membrane proteins in native lipid bilayers. An increasing number and complexity of integral membrane protein structures have been determined by solid-state NMR using two main methods. Oriented sample solid-state NMR uses macroscopically aligned lipid bilayers to obtain orientational restraints that define secondary structure and global fold of embedded peptides and proteins and their orientation and topology in lipid bilayers. Magic angle spinning (MAS) solid-state NMR uses unoriented rapidly spinning samples to obtain distance and torsion angle restraints that define tertiary structure and helix packing arrangements. Details of all current protein structures are described, highlighting developments in experimental strategy and other technological advancements. Some structures originate from combining solid- and solution-state NMR information and some have used solid-state NMR to refine X-ray crystal structures. Solid-state NMR has also validated the structures of proteins determined in different membrane mimetics by solution-state NMR and X-ray crystallography and is therefore complementary to other structural biology techniques. By continuing efforts in identifying membrane protein targets and developing expression, isotope labelling and sample preparation strategies, probe technology, NMR experiments, calculation and modelling methods and combination with other techniques, it should be feasible to determine the structures of many more membrane proteins of biological and biomedical importance using solid-state NMR. This will provide three-dimensional structures and atomic-resolution structural information for characterising ligand and drug interactions, dynamics and molecular mechanisms of membrane proteins under physiological lipid bilayer conditions. PMID:26857803

  17. Measurement of carbon flux through the MEP pathway for isoprenoid synthesis by (31)P-NMR spectroscopy after specific inhibition of 2-C-methyl-d-erythritol 2,4-cyclodiphosphate reductase. Effect of light and temperature.

    PubMed

    Mongélard, Gaëlle; Seemann, Myriam; Boisson, Anne-Marie; Rohmer, Michel; Bligny, Richard; Rivasseau, Corinne

    2011-08-01

    The methylerythritol 4-phosphate (MEP) and the mevalonate pathways are the unique synthesis routes for the precursors of all isoprenoids. An original mean to measure the carbon flux through the MEP pathway in plants is proposed by using cadmium as a total short-term inhibitor of 2-C-methyl-d-erythritol 2,4-cyclodiphosphate (MEcDP) reductase (GcpE) and measuring the accumulation rate of its substrate MEcDP by (31) P-NMR spectroscopy. The MEP pathway metabolic flux was determined in spinach (Spinacia oleracea), pea (Pisum sativum), Oregon grape (Mahonia aquifolium) and boxwood (Buxus sempervirens) leaves. In spinach, flux values were compared with the synthesis rate of major isoprenoids. The flux increases with light intensity (fourfold in the 200-1200 µmol m(-2) s(-1) PPFR range) and temperature (sevenfold in the 25-37 °C range). The relationship with the light and the temperature dependency of isoprenoid production downstream of the MEP pathway is discussed.

  18. A study of hydrogen-bond dynamics in carboxylic acids by NMR T1 measurements: isotope effects and hydrogen-bond length dependence

    NASA Astrophysics Data System (ADS)

    Agaki, T.; Imashiro, F.; Terao, T.; Hirota, N.; Hayashi, S.

    1987-08-01

    Proton (deuteron) transfer of hydrogen bonds in benzoic, glutaric and p-formylbenzoic acids was studied by proton (deuteron) T1 measurements. Deuteration of carboxylic protons was found to increase the barriers to classical proton jumping as well as quantum-mechanical tunneling. The former barriers increase as the hydrogen-bond distance increases.

  19. Pulsed NMRON relaxation measurements and thermometric NMR in the quasi-2 dimensional femomagnet: Mn(COOCH 3) 2·4H 2O

    NASA Astrophysics Data System (ADS)

    Le Gros, M.; Kotlicld, A.; Turrell, B. G.

    1990-08-01

    The measurement of the field dependence of the nuclear spin-lattice relaxation time of 54Mn in the two manganese sites in the quasi-2 dimensional ferromagnet Mn(COOCH 3) 2·4H 20 obtained by the pulsed NMRON technique is reported. This technique allows the observation in low fields of the higher frequency resonance which previously could not be measured by CW methods. The anomaly in the 54Mn relaxation time observed in the 55Mn level crossing regime is discussed, and the thermometric observation of the field dependence and lice width of the resonance lines from the abundant 55Mn spin systems is reported and related to the 54Mn spin-lattice relaxation behavior.

  20. 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

  1. Water absorption in mortar determined by NMR.

    PubMed

    Pel, L; Hazrati, K; Kopinga, K; Marchand, J

    1998-01-01

    Nuclear magnetic resonance (NMR) offers the possibility to determine moisture profiles in porous building materials. Moreover, the relaxation of the nuclear magnetic resonance signal can provide additional information on the water distribution in the microstructure. For mortar, it is shown that the transverse relaxation yields information on the distribution of water in the gel pores and capillary pores. Moisture profiles and relaxation were measured during water absorption. The effect of the drying treatment on the microstructure and the water absorption was investigated.

  2. Self-diffusion measurements of methanol and 1-decanol in supercritical CO{sub 2} by {sup 13}C pulsed field gradient NMR

    SciTech Connect

    Bai, S.; Mayne, C.L.; Grant, D.M.; Taylor, C.M.V.

    1997-10-01

    A small amount of a highly polar compound, such as methanol, is frequently added to supercritical fluid (SCF) carbon dioxide to enhance its ability to dissolve polar molecules in SCF separation technology. Few diffusion coefficients in SCF mixtures have been reported in the literature. The pulsed field gradient spin-echo technique (PGSE) has been used extensively to measure self-diffusion in neat monohydric alcohols under pressure. Hurle et al. and Luedemann et al. showed that the experimental diffusion coefficients of methanol may be explained by a rough hard-sphere model (RHS) with a roughness parameter, A. In this paper, diffusion measurements are reported for CO{sub 2}-methanol and CO{sub 2}-decanol mixtures in supercritical fluids. Since methanol in CO{sub 2} is primarily monomeric at low concentration, the RHS model, that is accurate for most simple, non-associated liquids, should apply. Previous nuclear spin-lattice relaxation studies in SCF CO{sub 2} suggest a large local solvent density enhancement, or solvent clustering, near a alcohol solute molecule under SCF conditions. If solvent clustering occurs in the vicinity of alcohol solute molecules, it should affect the diffusion coefficients. The authors have made the requisite measurements and found that they corroborate their previous spin-relaxation data.

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. 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

  16. High Resolution non-Markovianity in NMR

    PubMed Central

    Bernardes, Nadja K.; Peterson, John P. S.; Sarthour, Roberto S.; Souza, Alexandre M.; Monken, C. H.; Roditi, Itzhak; Oliveira, Ivan S.; Santos, Marcelo F.

    2016-01-01

    Memoryless time evolutions are ubiquitous in nature but often correspond to a resolution-induced approximation, i.e. there are correlations in time whose effects are undetectable. Recent advances in the dynamical control of small quantum systems provide the ideal scenario to probe some of these effects. Here we experimentally demonstrate the precise induction of memory effects on the evolution of a quantum coin (qubit) by correlations engineered in its environment. In particular, we design a collisional model in Nuclear Magnetic Resonance (NMR) and precisely control the strength of the effects by changing the degree of correlation in the environment and its time of interaction with the qubit. We also show how these effects can be hidden by the limited resolution of the measurements performed on the qubit. The experiment reinforces NMR as a test bed for the study of open quantum systems and the simulation of their classical counterparts. PMID:27669652

  17. Identification of 2-enolbutyrate as the product of the reaction of maize leaf phosphoenolpyruvate carboxylase with (Z)- and (E)-2-phosphoenolbutyrate: evidence from NMR and kinetic measurements

    SciTech Connect

    Gonzalez, D.H.; Andreo, C.S.

    1988-01-12

    (Z)- and (E)-2-phosphoenolbutyrates were dephosphorylated at similar rates by phosphoenolpyruvate carboxylase purified from maize leaves, as determined from proton nuclear magnetic resonance measurements. The product of the reaction in D/sub 2/O was a mixture of 60-70% 2-oxo(3-H,D)butyrate, 25-30% 2-oxo(3-D/sub 2/) butyrate, and 5-10% 2-oxo(3-H/sub 2/) butyrate. The amounts of (R)- and (S)-2-oxo(3-H,D) butyrate in this mixture were determined by exchange at C-3 in D/sup 2/O catalyzed by pyruvate kinase as described previously. Forty-five minutes after the addition of pyruvate kinase, the proportions of 2-oxo(3-H,D) butyrate and 2-oxo(3-D/sub 2/)-butyrate were 36-39% and 61-64%, respectively, indicating that the original mixture contained equal amounts of R and S enantiomers. In addition, a compound with properties similar to those of enolpyruvate was detected in solution during the action of phosphoenolpyruvate carboxylase on 2-phosphoenolbutyrate. This compound, most likely 2-enolbutyrate, presented maximum light absorption at 220-230 nm and was ketonized in a solution containing 80% D/sub 2/O and 20% H/sub 2/O (pH 7) with a rate constant of 1.33 min/sup -1/. From these results, it is concluded that the actual product released from the active site of phosphoenolpyruvate carboxylase during the reaction with 2-phosphoenolbutyrate is the enolic form of 2-oxobutyrate and that protonation of this form takes place at random in solution.

  18. 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.

  19. Method development in quantitative NMR towards metrologically traceable organic certified reference materials used as (31)P qNMR standards.

    PubMed

    Weber, Michael; Hellriegel, Christine; Rueck, Alexander; Wuethrich, Juerg; Jenks, Peter; Obkircher, Markus

    2015-04-01

    Quantitative nuclear magnetic resonance (qNMR) spectroscopy is employed by an increasing number of analytical and industrial laboratories for the assignment of content and quantitative determination of impurities. Within the last few years, it was demonstrated that (1)H qNMR can be performed with high accuracy leading to measurement uncertainties below 1 % relative. It was even demonstrated that the combination of (1)H qNMR with metrological weighing can lead to measurement uncertainties below 0.1 % when highly pure substances are used. Although qNMR reference standards are already available as certified reference materials (CRM) providing traceability on the basis of (1)H qNMR experiments, there is an increasing demand for purity assays on phosphorylated organic compounds and metabolites requiring CRM for quantification by (31)P qNMR. Unfortunately, the number of available primary phosphorus standards is limited to a few inorganic CRM which only can be used for the analysis of water-soluble analytes but fail when organic solvents must be employed. This paper presents the concept of value assignment by (31)P qNMR measurements for the development of CRM and describes different approaches to establish traceability to primary Standard Reference Material from the National Institute of Standards and Technology (NIST SRM). Phosphonoacetic acid is analyzed as a water-soluble CRM candidate, whereas triphenyl phosphate is a good candidate for the use as qNMR reference material in organic solvents. These substances contain both nuclei, (1)H and (31)P, and the concept is to show that it is possible to indirectly quantify a potential phosphorus standard via its protons using (1)H qNMR. The same standard with its assigned purity can then be used for the quantification of an analyte via its phosphorus using (31)P qNMR. For the validation of the concept, triphenyl phosphate and phosphonoacetic acid have been used as (31)P qNMR standards to determine the purity of the analyte

  20. Method development in quantitative NMR towards metrologically traceable organic certified reference materials used as (31)P qNMR standards.

    PubMed

    Weber, Michael; Hellriegel, Christine; Rueck, Alexander; Wuethrich, Juerg; Jenks, Peter; Obkircher, Markus

    2015-04-01

    Quantitative nuclear magnetic resonance (qNMR) spectroscopy is employed by an increasing number of analytical and industrial laboratories for the assignment of content and quantitative determination of impurities. Within the last few years, it was demonstrated that (1)H qNMR can be performed with high accuracy leading to measurement uncertainties below 1 % relative. It was even demonstrated that the combination of (1)H qNMR with metrological weighing can lead to measurement uncertainties below 0.1 % when highly pure substances are used. Although qNMR reference standards are already available as certified reference materials (CRM) providing traceability on the basis of (1)H qNMR experiments, there is an increasing demand for purity assays on phosphorylated organic compounds and metabolites requiring CRM for quantification by (31)P qNMR. Unfortunately, the number of available primary phosphorus standards is limited to a few inorganic CRM which only can be used for the analysis of water-soluble analytes but fail when organic solvents must be employed. This paper presents the concept of value assignment by (31)P qNMR measurements for the development of CRM and describes different approaches to establish traceability to primary Standard Reference Material from the National Institute of Standards and Technology (NIST SRM). Phosphonoacetic acid is analyzed as a water-soluble CRM candidate, whereas triphenyl phosphate is a good candidate for the use as qNMR reference material in organic solvents. These substances contain both nuclei, (1)H and (31)P, and the concept is to show that it is possible to indirectly quantify a potential phosphorus standard via its protons using (1)H qNMR. The same standard with its assigned purity can then be used for the quantification of an analyte via its phosphorus using (31)P qNMR. For the validation of the concept, triphenyl phosphate and phosphonoacetic acid have been used as (31)P qNMR standards to determine the purity of the analyte

  1. Overview of the development of high-resolution 920 MHz NMR in NIMS

    NASA Astrophysics Data System (ADS)

    Shimizu, Tadashi; Hashi, Kenjiro; Goto, Atsushi; Tansyo, Masataka; Kiyoshi, Tsukasa; Matsumoto, Shinji; Wada, Hitoshi; Fujito, Teruaki; Hasegawa, Ken-ichi; Kirihara, Noriaki; Suematsu, Hiroto; Kida, Yoshiki; Yoshikawa, Masatoshi; Miki, Takashi; Ito, Satoshi; Hamada, Mamoru; Hayashi, Seiji

    2004-04-01

    We have developed a 920 MHz NMR system and performed the proton NMR measurement of ethylbenzene and water using the superconducting magnet operating at 21.6 T ( 920 MHz for proton), which is the highest field produced by a superconducting NMR magnet in the persistent mode. From the NMR measurements, it is verified that both homogeneity and stability of the magnet have a specification sufficient for a high-resolution NMR. The sensitivity has been examined by 1H NMR of 0.1% ethylbenzene in Wilmad 555 tube and obtained the signal-to-noise ratio as S/ N=2981, which is the highest record, to our knowledge, among the room temperature measurements.

  2. 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.

  3. Compact orthogonal NMR field sensor

    SciTech Connect

    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.

  4. NMR characterization of thin films

    DOEpatents

    Gerald II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2010-06-15

    A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

  5. NMR characterization of thin films

    DOEpatents

    Gerald, II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2008-11-25

    A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

  6. 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.

  7. 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.

  8. Automated protein NMR resonance assignments.

    PubMed

    Wan, Xiang; Xu, Dong; Slupsky, Carolyn M; Lin, Guohui

    2003-01-01

    NMR resonance peak assignment is one of the key steps in solving an NMR protein structure. The assignment process links resonance peaks to individual residues of the target protein sequence, providing the prerequisite for establishing intra- and inter-residue spatial relationships between atoms. The assignment process is tedious and time-consuming, which could take many weeks. Though there exist a number of computer programs to assist the assignment process, many NMR labs are still doing the assignments manually to ensure quality. This paper presents (1) a new scoring system for mapping spin systems to residues, (2) an automated adjacency information extraction procedure from NMR spectra, and (3) a very fast assignment algorithm based on our previous proposed greedy filtering method and a maximum matching algorithm to automate the assignment process. The computational tests on 70 instances of (pseudo) experimental NMR data of 14 proteins demonstrate that the new score scheme has much better discerning power with the aid of adjacency information between spin systems simulated across various NMR spectra. Typically, with automated extraction of adjacency information, our method achieves nearly complete assignments for most of the proteins. The experiment shows very promising perspective that the fast automated assignment algorithm together with the new score scheme and automated adjacency extraction may be ready for practical use. PMID:16452794

  9. 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.

  10. A NMR characterisation of a banded sandstone.

    PubMed

    Bolam, A C; Packer, K J

    1998-01-01

    1H-nuclear magnetic resonance (NMR) measurements have been carried out on a banded sandstone to investigate the effects of structural inhomogeneities on the fluid dynamics of the sample as a whole. The results obtained from average propagator measurements (the probability of a displacement z in a time delta or P delta (z)) using pulsed-field-gradient techniques have been compared to those obtained from a study of a homogeneous sandstone. Relaxation has been used to derive the pore sizes for the differing bands and have been found to correlate with flow velocities within the bands.

  11. 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.

  12. NMR Studies of Cartilage Dynamics, Diffusion, Degradation

    NASA Astrophysics Data System (ADS)

    Huster, Daniel; Schiller, Jurgen; Naji, Lama; Kaufmann Jorn; Arnold, Klaus

    An increasing number of people is suffering from rheumatic diseases, and, therefore, methods of early diagnosis of joint degeneration are urgently required. For their establishment, however, an improved knowledge about the molecular organisation of cartilage would be helpful. Cartilage consists of three main components: Water, collagen and chondroitin sulfate (CS) that is (together with further polysaccharides and proteins) a major constituent of the proteoglycans of cartilage. 1H and 13C MAS (magic-angle spinning) NMR (nuclear magnetic resonance) opened new perspectives for the study of the macromolecular components in cartilage. We have primarily studied the mobilities of CS and collagen in bovine nasal and pig articular cartilage (that differ significantly in their collagen/polysaccharide content) by measuring 13C NMR relaxation times as well as the corresponding 13C CP (cross polarisation) MAS NMR spectra. These data clearly indicate that the mobility of cartilage macromolecules is broadly distributed from almost completely rigid (collagen) to highly mobile (polysaccharides), which lends cartilage its mechanical strength and shock-absorbing properties.

  13. NMR Studies of Dynamic Biomolecular Conformational Ensembles

    PubMed Central

    Torchia, Dennis A.

    2015-01-01

    Multidimensional heteronuclear NMR approaches can provide nearly complete sequential signal assignments of isotopically enriched biomolecules. The availability of assignments together with measurements of spin relaxation rates, residual spin interactions, J-couplings and chemical shifts provides information at atomic resolution about internal dynamics on timescales ranging from ps to ms, both in solution and in the solid state. However, due to the complexity of biomolecules, it is not possible to extract a unique atomic-resolution description of biomolecular motions even from extensive NMR data when many conformations are sampled on multiple timescales. For this reason, powerful computational approaches are increasingly applied to large NMR data sets to elucidate conformational ensembles sampled by biomolecules. In the past decade, considerable attention has been directed at an important class of biomolecules that function by binding to a wide variety of target molecules. Questions of current interest are: “Does the free biomolecule sample a conformational ensemble that encompasses the conformations found when it binds to various targets; and if so, on what time scale is the ensemble sampled?” This article reviews recent efforts to answer these questions, with a focus on comparing ensembles obtained for the same biomolecules by different investigators. A detailed comparison of results obtained is provided for three biomolecules: ubiquitin, calmodulin and the HIV-1 trans-activation response RNA. PMID:25669739

  14. Quantitative calibration of radiofrequency NMR Stark effects

    NASA Astrophysics Data System (ADS)

    Tarasek, Matthew R.; Kempf, James G.

    2011-10-01

    Nuclear magnetic resonance (NMR) Stark responses can occur in quadrupolar nuclei for an electric field oscillating at twice the usual NMR frequency (2ω0). Calibration of responses to an applied E field is needed to establish nuclear spins as probes of native E fields within material and molecular systems. We present an improved approach and apparatus for accurate measurement of quadrupolar Stark effects. Updated values of C14 (the response parameter in cubic crystals) were obtained for both 69Ga and 75As in GaAs. Keys to improvement include a modified implementation of voltage dividers to assess the 2ω0 amplitude, |E|, and the stabilization of divider response by reduction of stray couplings in 2ω0 circuitry. Finally, accuracy was enhanced by filtering sets of |E| through a linear response function that we established for the radiofrequency amplifier. Our approach is verified by two types of spectral results. Steady-state 2ω0 excitation to presaturate NMR spectra yielded C14 = (2.59 ± 0.06) × 1012 m-1 for 69Ga at room-temperature and 14.1 T. For 75As, we obtained (3.1 ± 0.1) × 1012 m-1. Both values reconcile with earlier results from 77 K and below 1 T, whereas current experiments are at room temperature and 14.1 T. Finally, we present results where few-microsecond pulses of the 2ω0 field induced small (tens of Hz) changes in high-resolution NMR line shapes. There too, spectra collected vs |E| agree with the model for response, further establishing the validity of our protocols to specify |E|.

  15. Solid-state NMR characterization of Mowry Formation shales

    SciTech Connect

    Miknis, F.P.

    1992-04-01

    Solid-state {sup 13}C and {sup 29}Si NMR measurements were carried out on a series of petroleum source rocks from the Mowry Formation of the Powder River Basin in Wyoming. The objectives of this study wereto use CP/MAS {sup 13}C NMR measurements to monitor changes in the carbon structure of the kerogen that result from depth of burial, and to examine the feasibility of {sup 29}Si NMR for studying the thermal alteration of clay minerals during diagenesis. Carbon and silicon NMR measurements were made on a suite of samples covering a present-day depth interval of 3,000 to 11,500 ft.In general, the NMR results endorsed other geochemical analyses that were performed on the source rocks as part of another study to examine pressure compartmentalization in the Mowry Formation. The carbon aromaticity of the kerogen increased with depth of burial, and at depths greater that approximately 10,000 ft the kerogen showed little capacity to generate additional oil because of the small fraction of residual aliphatic carbon. By combining NMR and Rock-Eval measurements, an estimate of the hydrogen budget was obtained. The calculations indicated that approximately 20% of the kerogen was converted to hydrocarbons, and that sufficient hydrogen was liberated from aromatization and condensation reactions to stabilize the generated products. The {sup 29}Si NMR spectra were characterized by a relatively sharp quartz resonance and a broad resonance from the clay minerals. With increasing depth of burial, the clay resonance became broader and shifted slightly downfield. These changes qualitatively support X-ray analysis that shows progressive alteration of illite to smectite with depth of burial.

  16. Solid-state NMR characterization of Mowry Formation shales

    SciTech Connect

    Miknis, F.P.

    1992-04-01

    Solid-state [sup 13]C and [sup 29]Si NMR measurements were carried out on a series of petroleum source rocks from the Mowry Formation of the Powder River Basin in Wyoming. The objectives of this study wereto use CP/MAS [sup 13]C NMR measurements to monitor changes in the carbon structure of the kerogen that result from depth of burial, and to examine the feasibility of [sup 29]Si NMR for studying the thermal alteration of clay minerals during diagenesis. Carbon and silicon NMR measurements were made on a suite of samples covering a present-day depth interval of 3,000 to 11,500 ft.In general, the NMR results endorsed other geochemical analyses that were performed on the source rocks as part of another study to examine pressure compartmentalization in the Mowry Formation. The carbon aromaticity of the kerogen increased with depth of burial, and at depths greater that approximately 10,000 ft the kerogen showed little capacity to generate additional oil because of the small fraction of residual aliphatic carbon. By combining NMR and Rock-Eval measurements, an estimate of the hydrogen budget was obtained. The calculations indicated that approximately 20% of the kerogen was converted to hydrocarbons, and that sufficient hydrogen was liberated from aromatization and condensation reactions to stabilize the generated products. The [sup 29]Si NMR spectra were characterized by a relatively sharp quartz resonance and a broad resonance from the clay minerals. With increasing depth of burial, the clay resonance became broader and shifted slightly downfield. These changes qualitatively support X-ray analysis that shows progressive alteration of illite to smectite with depth of burial.

  17. Stabilization of green bodies via sacrificial gelling agent during electrophoretic deposition

    DOEpatents

    Worsley, Marcus A.; Kuntz, Joshua D.; Rose, Klint A.

    2016-03-22

    In one embodiment, a method for electrophoretic deposition of a three-dimensionally patterned green body includes suspending a first material in a gelling agent above a patterned electrode of an electrophoretic deposition (EPD) chamber, and gelling the suspension while applying a first electric field to the suspension to cause desired patterning of the first material in a resulting gelation. In another embodiment, a ceramic, metal, or cermet includes a plurality of layers, wherein each layer includes a gradient in composition, microstructure, and/or density in an x-y plane oriented parallel to a plane of deposition of the plurality of layers along a predetermined distance in a z-direction perpendicular to the plane of deposition.

  18. Cobalt ferrite nanoparticles with improved aqueous colloidal stability and electrophoretic mobility

    NASA Astrophysics Data System (ADS)

    Munjal, Sandeep; Khare, Neeraj

    2016-04-01

    We have synthesized CoFe2O4 (CFO) nanoparticles of size ˜ 12.2 nm by hydrothermal synthesis method. To control the size of these CFO nanoparticles, oleic acid was used as a surfactant. The inverse spinel phase of the synthesized nanoparticles was confirmed by X-ray diffraction method. As synthesized oleic acid coated CFO (OA@CFO) nanoparticles has very less electrophoretic mobility in the water and are not water dispersible. These OA@CFO nanoparticles were successfully turned into water soluble phase with a better colloidal aqueous stability, through a chemical treatment using citric acid. The modified citric acid coated CFO (CA@CFO) nanoparticles were dispersible in water and form a stable aqueous solution with high electrophoretic mobility.

  19. Electrophoretic purification of cells in space - Evaluation of results from STS-3

    NASA Technical Reports Server (NTRS)

    Sarnoff, B. E.; Kunze, M. E.; Todd, P.

    1983-01-01

    The procedure and results of Electrophoresis Equipment Verification Test, designed to examine electrophoretic behavior of animal cells is suspension more concentrated than possible on earth and flown on the Shuttle flight STS-3, were discussed. Ground-based laboratory values of electrophoretic mobilities of a mixture of human and rabbit aldehyde-fixed red blood cells (RBC) were compared with those recorded at 11 minute intervals on the Shuttle STS-3. RBC migration and separation observed through photographic records were not as expected. However, cell mobilities and migrating band profiles were consistent with the results of laboratory simulation experiments. It was concluded that zero G electrophoresis of very high concentrations (1 x 10 to the 9th) is possible and similar to electrophoresis of normal cell concentrations on earth.

  20. Optimized conditions for pulsed field gel electrophoretic separations of DNA.

    PubMed Central

    Birren, B W; Lai, E; Clark, S M; Hood, L; Simon, M I

    1988-01-01

    Quantitative measurement of DNA migration in gel electrophoresis requires precisely controlled homogeneous electric fields. A new electrophoresis system has allowed us to explore several parameters governing DNA migration during homogeneous field pulsed field gel (PFG) electrophoresis. Migration was measured at different switch times, temperatures, agarose concentrations, and voltage gradients. Conditions which increase DNA velocities permit separation over a wider size range, but reduce resolution. We have also varied the angle between the alternating electric fields. Reorientation angles between 105 degrees and 165 degrees give equivalent resolution, despite significant differences in DNA velocity. Separation of DNA fragments from 50 to greater than 7000 kilobases (Kb) can easily be optimized for speed and resolution based on conditions we describe. Images PMID:3412895