Magnetic Relaxation Studies Research Articles

Micellar fluidity. A deuterium nuclear magnetic resonance spin relaxation study of the anisotropic reorientation of solubilized trans-Decalin-d18

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMicellar fluidity. A deuterium nuclear magnetic resonance spin relaxation study of the anisotropic reorientation of solubilized trans-Decalin-d18Peter Stilbs, Harald Walderhaug, and Bjoern LindmanCite this: J. Phys. Chem. 1983, 87, 23, 4762–4769Publication Date (Print):November 1, 1983Publication History Published online1 May 2002Published inissue 1 November 1983https://doi.org/10.1021/j100246a042RIGHTS & PERMISSIONSArticle Views90Altmetric-Citations22LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts

Carbon-13 nuclear magnetic relaxation study of silk protein

Carbon-13 nuclear spin-lattice relaxation measurements of liquid silk protein in the silk gland have been made in both the native and denatured states. It has been found that the relaxation process consists of non-exponential decays for the carbon of glycine in the native silk protein. On the other hand, a single exponential decay has been observed for the denatured one. From these results it has been suggested that carbon in glycine in the native silk protein takes two different conformations.

Structure of alamethicin in solution: nuclear magnetic resonance relaxation studies.

An NMR relaxation study at 500 MHz of the icosapeptide antibiotic alamethicin is reported. This study lends further support to the partly helical, partly extended, amphiphilic, and dimeric structure recently proposed for this peptide in methanolic solutions [Banerjee, U., Tsui, F. P., Balasubramanian, T. N., Marshall, G. R., & Chan, S. I. (1983) J. Mol. Biol. 165, 757]. The N-acetyl methyl groups toward the N terminus of alamethicin in this solvent system were found to exhibit unusual NMR relaxation behavior. The decay of the transverse magnetization due to these protons was nonexponential, but the spin-lattice relaxation recovery of the longitudinal magnetization was exponential. In a solution saturated with urea, however, both decays were exponential. These observations are shown to be consistent with the proposed structure. Studies in water yielded qualitatively similar but more complex results. The transverse relaxation times suggest further aggregation in water and indicate that the larger aggregates in water may be made up of the smaller units observed in methanol.

ChemInform Abstract: NUCLEAR MAGNETIC RELAXATION STUDY OF FULLY DEUTERATED SULFOLAN

Chemischer InformationsdienstVolume 14, Issue 27 Physical Organic Chemistry ChemInform Abstract: NUCLEAR MAGNETIC RELAXATION STUDY OF FULLY DEUTERATED SULFOLAN H. PEEMOELLER, H. PEEMOELLERSearch for more papers by this authorA. R. SHARP, A. R. SHARPSearch for more papers by this authorA. WATTON, A. WATTONSearch for more papers by this authorD. W. KYDON, D. W. KYDONSearch for more papers by this author H. PEEMOELLER, H. PEEMOELLERSearch for more papers by this authorA. R. SHARP, A. R. SHARPSearch for more papers by this authorA. WATTON, A. WATTONSearch for more papers by this authorD. W. KYDON, D. W. KYDONSearch for more papers by this author First published: July 5, 1983 https://doi.org/10.1002/chin.198327069AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume14, Issue27July 5, 1983 RelatedInformation

29Si nuclear magnetic resonance and relaxation in the paramagnetic state of CeCu 2Si 2

29Si nuclear magnetic resonance (NMR) and relaxation studies of the unstable-moment compound CeCu 2Si 2 have been carried out to probe the electronic state of the nearly-trivalent Ce ions. Isotropic and anisotropic NMR shifts indicate effects of both crystalline electric fields (CEF) and low-temperature moment reduction on the Ce ionic states. A relatively large anisotropic shift was observed at low temperatures, and also obtained from a CEF-state calculation in the molecular-field approximation. The hyperfine coupling also appears to be anisotropic, although this is not manifested in the temperature dependence of the shift due to changing CEF-state populations. NMR estimates of the Ce-spin fluctuation time vary with temperature in a manner similar to the neutron quasielastic scattering linewidth at high temperatures, but suggest the onset of spatially coherent fluctuations.

Structure of micellar solutions of nonionic surfactants. Nuclear magnetic resonance self-diffusion and proton relaxation studies of poly(ethylene oxide) alkyl ethers

Structure of micellar solutions of nonionic surfactants. Nuclear magnetic resonance self-diffusion and proton relaxation studies of poly(ethylene oxide) alkyl ethers

Nuclear magnetic relaxation study of fully deuterated sulfolan

Molecular motions of the fully deuterated sulfolan molecule (C4D8O2S) have been studied in the solid state by NMR measurements of the deuteron spin-lattice relaxation times in the laboratory (T1) and rotating (T1ρ) frame. In the crystalline phase, it has been found that the relaxation is determined by the ring puckering motion of the molecule. The plastic crystal phase is found to exhibit effects from both isotropic reorientation and translational diffusion. The modified nature of this phase and the plastic–crystalline transition of the deuterated as compared to the undeuterated solid is discussed in terms of the C–H—O hydrogen bonding between molecules.

Deuteron nuclear magnetic relaxation study of water adsorbed on oriented cellulose

A deuteron N.M.R. study of the dynamics and ordering of water adsorbed on macroscopically oriented cellulose fibres was made. The quadrupolar splitting, the decay of the quadrupolar echo, T 2, and spin-lattice relaxation times T 1Z and T 1Q were measured. From these relaxation times the spectral densities J 0(0), J 1(ω0) and J 2(2ω0) were calculated. An interpretation of the difference between the spectral densities, based on the ‘slowly relaxing water structure’ at the fibre surface, is given.

Raman Scattering: Fast Axial Rotation of Methylhalides and Acetonitrile in the Liquid State

AbstractThe temperature dependence of the degenerate methyl stretching Raman profiles of CH3CN, CH3I, CD3I, CH3Cl, and CH3F and, further, for CH3CN the pressure dependence are investigated. The Raman bands are analysed in terms of the small angle diffusion and the J‐diffusion model both with and without Coriolis interaction. The comparison with the small angle diffusion model is carried out in the frequency domain. For the analysis in terms of the J‐diffusion model, first experimental orientational correlation functions are calculated. Then, by following theoretical arguments, the overall correlation function is decomposed into two partial correlation functions g(2)1(t) and g(2)2(t). There is limited agreement with previous magnetic relaxation studies on the fast axial spinning motion. In particular, it is found that the partial correlation function g(2)2(t) shows little temperature and pressure dependence, which cannot satisfactorily be accounted for by the existing models.

A nuclear magnetic relaxation study of conformational changes induced by substrate and temperature in bovine liver thiosulfate sulfurtransferase and yeast hexokinase

Nuclear magnetic relaxation studies have been performed on thiosulfate sulfurtransferase (EC 2.8.1.1) and hexokinase (EC 2.7.1.1). Observation of proton spin-lattice relaxation times T 1 indicates that structural transitions occur in these enzymes in the range 0–40°C and that there are different temperature-dependent forms of thiosulfate sulfurtransferase and hexokinase. Thermal transitions between these forms are affected by the binding of the substrates. The results may be due to changes in the interactions between the structural domains into which the single polypeptide chains of thiosulfate sulfurtransferase and hexokinase are folded.

A deuteron and proton magnetic resonance relaxation study of β-lactoglobulin A association: Some approaches to the scatchard hydration of globular proteins

A general expression for the concentration-dependent relaxation increment, ( dR dc ) μ , (where R may be R 1, the spin-lattice, or R 2, the spin-spin relaxation rate of water), has been derived from multicomponent theory for a protein in salt solution. Emphasis is placed on the addition of salt to the aqueous protein to minimize potentially high virial effects due to charge repulsion or to the charge fluctuations predicted by the Kirkwood-Shumaker theory; under conditions where the protein has a high net charge-to-mass ratio the calculation of relaxation increments must employ protein activities in place of concentrations. This treatment was applied to the molecular states of β-lactoglobulin A under associating and nonassociating conditions. In contrast to data in the literature obtained in the absence of salt, where correlation times τ c were excessively high and hydration values too low, here values of τ c from 2H NMR were in quantitative agreement with those expected from parameters of the known structural states of this protein. With these values, hydrations were obtained by three different ways of calculating the relaxation rate of the bound water from 1H and 2H NMR data. Preferential hydrations, derived from linked functions, for the association of the protein at pH 4.65 were obtained from sedimentation velocity measurements. Combination of the results from the temperature dependence of the deuteron NMR and the linked functions, on the basis of a three-state model, yields slow-tumbling hydration values and correlation times comparable to those obtained from the two-state model. Based on either an isotropic bound-water mechanism or an anisotropic orientational distribution of the water molecules, enthalpies of hydration determined from the three-state model are in accord with those calculated from the two-state model.

A proton magnetic relaxation study of the anodic oxide layer of aluminum electrolytic capacitors and of bayerite

Proton resonances in (i) the hydrated oxides of the anodized foils of aluminum electrolytic capacitors and (ii) bayerite and boehmite were studied. The Sprague aged sample showed more protons associated with chemisorbed water than the Sprague fresh sample did. The thermal gravimetric analysis data show the same trend. The T 1 versus 1/T data for bayerite show a shallow minimum around — 11 °C and possibly a second minimum above 180 °C. The activation energy for the high temperature side of the T 1 minimum is 2.54 kcal mol −1 and compares well with the value of 1.8 kcal mol −1 for the longitudinal relaxation process in boehmite. The correlation times for bayerite show an almost log-normal distribution. The narrow lines observed in the wide-line spectra of both bayerite and boehmite are possibly due to extrinsic structure defects (proton vacancies and interstitials).

Nuclear magnetic spin-rotational relaxation times for linear molecules

Abstract The stochastic differential equation study of nuclear magnetic relaxation by spin-rotational interactions is applied to the linear rotator model of the molecule. Inertial effects are included in the calculations, which are performed analytically. Expressions are derived for the spin-rotational contributions to the longitudinal and transverse relaxation times, and for the spin-rotational correlation time.

Stochastic differential equation study of nuclear magnetic relaxation by spin-rotational interactions

The mathematical methods based on stochastic differential equations and the rotation operator, which were developed for the study of rotational Brownian motion and its implications for dielectric dispersion and absorption, are extended so as to yield ensemble averages of certain products of orientational and angular velocity functions. As a consequence, a procedure for calculating nuclear magnetic relaxation times arising from spin-rotational interactions, when inertial effects are included, is presented for molecules of any shape.

Long-range segmental motion in polymers: a carbon-13 nuclear magnetic resonance spin-lattice relaxation study of polyesters

Long-range segmental motion in polymers: a carbon-13 nuclear magnetic resonance spin-lattice relaxation study of polyesters

Nuclear magnetic resonance relaxation in nucleic acid fragments: models for internal motion.

A variety of models incorporating internal motion, which can be used to extract information from nuclear magnetic resonance relaxation studies of deoxyribonucleic acid fragments, are formulated. Illustrative analyses of some recent multinuclear relaxation data are presented. Special emphasis is placed on determining whether the information extracted is unique. It is shown that the data are consistent with several physical pictures of the internal motion. However, all the models we have considered imply the existence of large-amplitude internal motions on the nanosecond time scale.

23Na +-NMR studies of cation binding to multi-chain and single-chain glycosaminoglycan peptides

1. 1. 23Na + nuclear magnetic relaxation studies of cation binding to single-chain chondroitin 4-sulphate and dermatan sulphate and a multi-chain chondroitin 4-sulphate-polypeptide complex have been performed. Excess relaxation rates (longitudinal and transverse) for the bound sodium have been measured during titration experiments. The data were used to calculate the correlation time and the fraction of bound ions. This approach was also used to analyze the relative affinities of Na +, K + and Ca 2+. 2. 2. The excess transverse relaxation rates for 23Na + (obtained from line-width measurements or the decay of transverse magnetization) in solutions of single-chain and multi-chain chondroitin sulphate were recorded as a function of the degree of neutralization. There was a steep increase in transverse relaxation rate for the multi-chain preparation around pH 7 which was not seen with single chains. This could be ascribed to an increase in the correlation time for bound sodium. The alteration in binding properties observed with multi-chained material around pH 7 suggested a change in the quadropolar coupling constant for 23Na in this range. The behaviour of a multi-chained specimen (as expressed in excess line-width) during titration gradually changed to that of single chains upon prolonged exposure to alkali. 3. 3. Competition experiments using KCl additions to multi-chained sodium chondroitin sulphate at pH 12.3 and 3.3 indicated that Na + and K + have very similar affinities at high pH. However, at low pH there was an increased affinity for K + (expressed as a faster decrease in excess relaxation rate when KCl was added). 4. 4. Competition experiments using multi-chain chondroitin sulphate and Ca 2+ at pH 11.4 showed increasing excess relaxation rates during the initial phase. Above 4 mM Ca 2+ simple exchange of bound Na + with Ca 2+ was observed. The former behaviour was not seen at pH 3.3 nor with single-chain chondroitin sul[hate at pH 11.4. It is suggested that endogeneous Ca 2+ present in the multi-chain preparation is responsible for the pH dependence. The increased excess transverse relaxation rate seen with the multi-chained specimen upon Ca 2+ additions was referred to an increase in the correlation time for bound Na +. 5. 5. The most likely explanation for the abrupt increase in correlation time for Na + bound to multi-chain chondroitin sulphate around pH 7 is an aggregation between the side-chains. In the presence of Ca 2+, cross-linking of chains (clustered together on the protein core) was promoted and the local mobility of the Na + ions was further reduced. In addition to the formation of Ca 2+ bridges between chains, the results also imply increased binding of counter ions owing to a higher local charge density.

ChemInform Abstract: DEUTERON NUCLEAR MAGNETIC RELAXATION STUDY OF THE ROTATION OF ADAMANTANE IN N‐ALKANES

Chemischer InformationsdienstVolume 12, Issue 35 Physical Organic Chemistry ChemInform Abstract: DEUTERON NUCLEAR MAGNETIC RELAXATION STUDY OF THE ROTATION OF ADAMANTANE IN N-ALKANES B. ANCIAN, B. ANCIANSearch for more papers by this authorB. TIFFON, B. TIFFONSearch for more papers by this authorJ.-E. DUBOIS, J.-E. DUBOISSearch for more papers by this author B. ANCIAN, B. ANCIANSearch for more papers by this authorB. TIFFON, B. TIFFONSearch for more papers by this authorJ.-E. DUBOIS, J.-E. DUBOISSearch for more papers by this author First published: September 1, 1981 https://doi.org/10.1002/chin.198135086AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue35September 1, 1981 RelatedInformation

Nuclear magnetic relaxation study of protonic motion in hydronium beta″-aluminas

The temperature dependence of proton T 1 and T 2 was measured at 20 MHz for polycrystalline hydronium beta″-alumina, its partially dehydrated phase, and potassium-hydronium beta″-aluminas. The protonic diffusion was recognized by motional narrowing of T 2 data for all samples. The activation energies of the diffusion are 19 and 24.5 kJ/mol for the fully hydrated and partially dehydrated hydronium beta″-alumina, respectively, indicating that the protonic translation becomes slower on dehydration. The proton relaxational behavior in potassium-hydronium beta″-alumina is similar to that of the hydronium analog, but its large activation energy (24 kJ/mol), suggests that the potassium ion on the conduction plane decreases the proton conductivity by acting as a blocking ion.

Magnetic relaxation study of solid ammonia–boron trifluoride complex

Proton and fluorine magnetic resonance absorption, and spin–lattice relaxation time measurements, have been carried out on crystalline ammonia–boron trifluoride complex in the temperature ranges from 4.2 to 300 K in the continuous wave method, and from 89 to 373 K using the pulse technique. The second moment results indicated that the BF3 motion is hindered at ∼200 K, as previously reported, while the NH3 group is considerably mobile at 77 K but an additional motion occurs at 4.2 K. The magnetization decay of 1H and 19F after a 180 ° pulse showed intrinsically nonexponential behavior. The T1 data, taken as the initial decay time constant, are compared with approximate theoretical estimates including three dissimilar spins. For the 19F relaxation at high temperature, a set of three differential rate equations was reduced to a pair of two differential equations in which the effect of the third atom is taken into account in the diagonal coefficients. The temperature dependence was almost completely predicted by this treatment. Three dipolar contributions 19F–19F, 19F–11B, and 19F–1H were found to be 1.244, 2.420, and 0.222×109 s−2 for the relaxation constants, respectively. A discrepancy between theory and experiment was observed in the 1H relaxation data at high temperature and for 19F at low temperature, both of which can not be explained by assuming a two-dissimilar-spins system and require the consideration of magnetic polarization in the third atom.