Physics and Astronomy › Nuclear and High Energy Physics

NMR spectroscopy and applications

Works Count: 41636

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Description

This cluster of papers covers a wide range of applications of Nuclear Magnetic Resonance (NMR) in fields such as geophysics, chemistry, hydrogeology, and cultural heritage. The papers discuss topics such as diffusion, relaxation, surface NMR, geophysical imaging, chemical analysis, and process monitoring using NMR techniques.

Keywords

Nuclear Magnetic Resonance; Diffusion; Relaxation; Porous Media; Surface NMR; Geophysical Imaging; Chemical Analysis; Process Monitoring; Hydrogeology; Cultural Heritage

Pulse and Fourier Transform NMR

1971-01-01

Thomas C. Farrar

Principles of Nuclear Magnetic Resonance Microscopy

1991-11-28

Paul T. Callaghan

Abstract Nuclear magnetic resonance imaging is best known for its spectacular use in medical tomography. However, the method has potential applications in biology, materials science, and chemical physics, some of … Abstract Nuclear magnetic resonance imaging is best known for its spectacular use in medical tomography. However, the method has potential applications in biology, materials science, and chemical physics, some of which have begun to be realized as laboratory NMR spectrometers have been adapted to enable small scale imaging. NMR microscopy has available a rich variety of contrast including molecular specificity and sensitivity to molecular dynamics. In NMR imaging the signal is acquired in k-space, a dimension which bears a Fourier relationship with the positions of nuclear spins. A dynamic analogue of k-space imaging is the Pulsed Gradient Spin Echo (PGSE) experiment in which the signal is acquired in q-space, conjugate to the distances moved by the spins over a well-defined time interval. q-space microsocpy provides images of the nuclear self-correlation function with a resolution some two orders of magnitude better than is possible in imaging the nuclear density. As well as revealing the spectrum of molecular motion, PGSE NMR can be used to study morphology in porous systems through the influence of motional boundaries. This book explores principles and common themes underlying these two variants of NMR Microscopy, providing many examples of their use. The methods discussed here are of importance in fundamental biological and physical research, as well as having applications in a wide variety of industries, including those concerned with petrochemicals, polymers, biotechnology, food processing, and natural product processing.

'Metabonomics': understanding the metabolic responses of living systems to pathophysiological stimuli via multivariate statistical analysis of biological NMR spectroscopic data

1999-01-01

Jeremy K. Nicholson , John C. Lindon , Elaine Holmes

(1999). 'Metabonomics': understanding the metabolic responses of living systems to pathophysiological stimuli via multivariate statistical analysis of biological NMR spectroscopic data. Xenobiotica: Vol. 29, No. 11, pp. 1181-1189. (1999). 'Metabonomics': understanding the metabolic responses of living systems to pathophysiological stimuli via multivariate statistical analysis of biological NMR spectroscopic data. Xenobiotica: Vol. 29, No. 11, pp. 1181-1189.

Bloch Equations with Diffusion Terms

1956-11-01

H. C. Torrey

The phenomenological Bloch equations in nuclear magnetic resonance are generalized by the addition of terms due to the transfer of magnetization by diffusion. The revised equations describe phenomena under conditions … The phenomenological Bloch equations in nuclear magnetic resonance are generalized by the addition of terms due to the transfer of magnetization by diffusion. The revised equations describe phenomena under conditions of inhomogeneity in magnetic field, relaxation rates, or initial magnetization. As an example the equations are solved in the case of the free precession of magnetic moment in the presence of an inhomogeneous magnetic field following the application of a 90\ifmmode^\circ\else\textdegree\fi{} pulse with subsequent applications of a succession of 180\ifmmode^\circ\else\textdegree\fi{} pulses. The spin-echo amplitudes agree with the results of Carr and Purcell from a random walk theory.

Elucidation of cross relaxation in liquids by two-dimensional N.M.R. spectroscopy

1980-09-01

Slobodan Macura , Richard R. Ernst

Abstract Two-dimensional N.M.R. spectroscopy is applied to the elucidation of cross relaxation pathways in liquids. The theory underlying two dimensional studies of cross relaxation and of transient nuclear Overhauser effects … Abstract Two-dimensional N.M.R. spectroscopy is applied to the elucidation of cross relaxation pathways in liquids. The theory underlying two dimensional studies of cross relaxation and of transient nuclear Overhauser effects is developed. The influence of the correlation time of the molecular random process is investigated. It is found that in the limit of short correlation times (extreme narrowing limit) weak negative cross-peaks are observed. However, for long correlation times (spin diffusion limit) strong positive cross-peaks can be obtained. The technique appears particularly promising for the study of cross relaxation in macromolecules. Examples of intra- and intermolecular cross relaxation in the extreme narrowing limit are presented. Additional informationNotes on contributorsS. Macura Academic Guest 1979–1980

Oxygenation dependence of the transverse relaxation time of water protons in whole blood at high field

1982-02-01

Keith R. Thulborn , John C. Waterton , Paul M. Matthews +1 more

Effects of Diffusion on Free Precession in Nuclear Magnetic Resonance Experiments

1954-05-01

H. Y. Carr , Edward M. Purcell

Nuclear resonance techniques involving free precession are examined, and, in particular, a convenient variation of Hahn's spin-echo method is described. This variation employs a combination of pulses of different intensity … Nuclear resonance techniques involving free precession are examined, and, in particular, a convenient variation of Hahn's spin-echo method is described. This variation employs a combination of pulses of different intensity or duration ("90-degree" and "180-degree" pulses). Measurements of the transverse relaxation time ${T}_{2}$ in fluids are often severely compromised by molecular diffusion. Hahn's analysis of the effect of diffusion is reformulated and extended, and a new scheme for measuring ${T}_{2}$ is described which, as predicted by the extended theory, largely circumvents the diffusion effect. On the other hand, the free precession technique, applied in a different way, permits a direct measurement of the molecular self-diffusion constant in suitable fluids. A measurement of the self-diffusion constant of water at 25\ifmmode^\circ\else\textdegree\fi{}C is described which yields $D=2.5(\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ ${\mathrm{cm}}^{2}$/sec, in good agreement with previous determinations. An analysis of the effect of convection on free precession is also given. A null method for measuring the longitudinal relaxation time ${T}_{1}$, based on the unequal-pulse technique, is described.

Principles of Nuclear Magnetic Resonance in One and Two Dimensions

1989-07-01

Richard R. Ernst , Geoffrey Bodenhausen , Alexander Wokaun +1 more

List of notation Introduction The dynamics of nuclear spin systems Manipulation of nuclear spin Hamiltonians One-dimensional Fourier spectroscopy Multiple-quantum transitions Two-dimensional Fourier spectroscopy Two-dimensional separation of interactions Two-dimensional correlation methods … List of notation Introduction The dynamics of nuclear spin systems Manipulation of nuclear spin Hamiltonians One-dimensional Fourier spectroscopy Multiple-quantum transitions Two-dimensional Fourier spectroscopy Two-dimensional separation of interactions Two-dimensional correlation methods based on coherence transfer Dynamic processes studied by two-dimensional exchange spectroscopy Nuclear magnetic resonance imaging References Index.

Maximum likelihood estimation of the polychoric correlation coefficient

1979-12-01

Ulf Olsson

Simplified CCSD(T)-F12 methods: Theory and benchmarks

2009-02-02

Gerald Knizia , Thomas B. Adler , Hans‐Joachim Werner

The simple and efficient CCSD(T)-F12x approximations (x = a,b) we proposed in a recent communication [T. B. Adler, G. Knizia, and H.-J. Werner, J. Chem. Phys. 127, 221106 (2007)] are … The simple and efficient CCSD(T)-F12x approximations (x = a,b) we proposed in a recent communication [T. B. Adler, G. Knizia, and H.-J. Werner, J. Chem. Phys. 127, 221106 (2007)] are explained in more detail and extended to open-shell systems. Extensive benchmark calculations are presented, which demonstrate great improvements in basis set convergence for a wide variety of applications. These include reaction energies of both open- and closed-shell reactions, atomization energies, electron affinities, ionization potentials, equilibrium geometries, and harmonic vibrational frequencies. For all these quantities, results better than the AV5Z quality are obtained already with AVTZ basis sets, and usually AVDZ treatments reach at least the conventional AVQZ quality. For larger molecules, the additional cost for these improvements is only a few percent of the time for a standard CCSD(T) calculation. For the first time ever, total reaction energies with chemical accuracy are obtained using valence-double-zeta basis sets.

Two-dimensional spectroscopy. Application to nuclear magnetic resonance

1976-03-01

W.P Aue , E. Bartholdi , Richard R. Ernst

The possibilities for the extension of spectroscopy to two dimensions are discussed. Applications to nuclear magnetic resonance are described. The basic theory of two-dimensional spectroscopy is developed. Numerous possible applications … The possibilities for the extension of spectroscopy to two dimensions are discussed. Applications to nuclear magnetic resonance are described. The basic theory of two-dimensional spectroscopy is developed. Numerous possible applications are mentioned and some of them treated in detail, including the elucidation of energy level diagrams, the observation of multiple quantum transitions, and the recording of high-resolution spectra in inhomogenous magnetic fields. Experimental results are presented for some simple spin systems.

A review of normal tissue hydrogen NMR relaxation times and relaxation mechanisms from 1–100 MHz: Dependence on tissue type, NMR frequency, temperature, species, excision, and age

1984-07-01

Paul A. Bottomley , Thomas H. Foster , R. E. Argersinger +1 more

The longitudinal (T1) and transverse (T2) hydrogen (1H) nuclear magnetic resonance (NMR) relaxation times of normal human and animal tissue in the frequency range 1-100 MHz are compiled and reviewed … The longitudinal (T1) and transverse (T2) hydrogen (1H) nuclear magnetic resonance (NMR) relaxation times of normal human and animal tissue in the frequency range 1-100 MHz are compiled and reviewed as a function of tissue type, NMR frequency, temperature, species, in vivo versus in vitro status, time after excision, and age. The dominant observed factors affecting T1 are tissue type and NMR frequency (V). All tissue frequency dispersions can be fitted to the simple expression T1 = AVB in the range 1-100 MHz, with A and B tissue-dependent constants. This equation provides as good or better fit to the data as previous more complex formulas. T2 is found to be multicomponent, essentially independent of NMR frequency, and dependent mainly on tissue type. Mean and raw values of T1 and T2 for each tissue are tabulated and/or plotted versus frequency and the fitting parameters A, B and the standard deviations determined to establish the normal range of relaxation times applicable to NMR imaging. The mechanisms for tissue NMR relaxation are reviewed with reference to the fast exchange two state (FETS) model of water in biological systems, and an overview of the dynamic state of water and macromolecular hydrogen compatible with the frequency, temperature, and multicomponent data is postulated. This suggests that 1H tissue T1 is determined predominantly by intermolecular (possibly rotational) interactions between macromolecules and a single bound hydration layer, and the T2 is governed mainly by exchange diffusion of water between the bound layer and a free water phase. Deficiencies in measurement techniques are identified as major sources of data irreproducibility.

Importance of classical diffusion in NMR studies of water in biological cells

1979-06-01

K. R. Brownstein , C. E. Tarr

Nuclear-magnetic-resonance measurements of the proton-spin relaxation for water in biological cells are known to exhibit a multiexponential decay. A theory, based on the diffusion equation using the bulk diffusivity of … Nuclear-magnetic-resonance measurements of the proton-spin relaxation for water in biological cells are known to exhibit a multiexponential decay. A theory, based on the diffusion equation using the bulk diffusivity of water, is developed to explain this phenomenon. It is shown that multiexponential decay arises simply as a consequence of an eigenvalue problem associated with the size and shape of the cell and that this multiexponential decay can only be observed for samples whose size is of the order of a biological cell. As an example, the theory is applied to a previously published data for rat gastronemius cells. Excellent agreement is obtained, and furthermore, the size of the cell is calculated by fitting the theory to the experiment.

NMR chemical shift imaging in three dimensions.

1982-06-01

Truman R. Brown , B. M. Kincaid , Kâmil Uğurbil

A method for obtaining the three-dimensional distribution of chemical shifts in a spatially inhomogeneous sample using Fourier transform NMR is presented. The method uses a sequence of pulsed field gradients … A method for obtaining the three-dimensional distribution of chemical shifts in a spatially inhomogeneous sample using Fourier transform NMR is presented. The method uses a sequence of pulsed field gradients to measure the Fourier transform of the desired distribution on a rectangular grid in (k,t) space. Simple Fourier inversion then recovers the original distribution. An estimated signal/noise ratio of 20 in 10 min is obtained for an "image" of the distribution of a 10 mM phosphorylated metabolite in the human head at a field of 20 kG with 2-cm resolution.

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Generalized multiparameter correlation for nonpolar and polar fluid transport properties

1988-04-01

Ting Horng Chung , Mohammad Ajlan , Lloyd L. Lee +1 more

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGeneralized multiparameter correlation for nonpolar and polar fluid transport propertiesTing Horng Chung, Mohammad Ajlan, Lloyd L. Lee, and Kenneth E. StarlingCite this: Ind. Eng. Chem. Res. 1988, … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGeneralized multiparameter correlation for nonpolar and polar fluid transport propertiesTing Horng Chung, Mohammad Ajlan, Lloyd L. Lee, and Kenneth E. StarlingCite this: Ind. Eng. Chem. Res. 1988, 27, 4, 671–679Publication Date (Print):April 1, 1988Publication History Published online1 May 2002Published inissue 1 April 1988https://pubs.acs.org/doi/10.1021/ie00076a024https://doi.org/10.1021/ie00076a024research-articleACS PublicationsRequest reuse permissionsArticle Views3752Altmetric-Citations866LEARN 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 InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Use of the Stimulated Echo in NMR Diffusion Studies

1970-03-01

J. E. Tanner

The stimulated echo in a three-rf-pulse experiment is shown to be useful in extending the range of measurement of diffusion coefficients to more viscous substances or the measurement of barrier … The stimulated echo in a three-rf-pulse experiment is shown to be useful in extending the range of measurement of diffusion coefficients to more viscous substances or the measurement of barrier separations to wider spacings in systems where the diffusing substance has T1 &gt; T2. The spin-echo attenuation due to self-diffusion is derived for the general case of a time-dependent field gradient, and the result is found experimentally to be correct for the special case of a field gradient applied in two equal, square pulses.

Selection of coherence-transfer pathways in NMR pulse experiments

1984-07-01

Geoffrey Bodenhausen , Herbert Kogler , Richard R. Ernst

Relative Permeability Calculations From Pore Size Distribution Data

1953-03-01

N.T. Burdine

Abstract Formulas for calculating relative permeability from pore size distribution data are derived from basic laws of fluid flow in porous media. The tortuosity factors that appear in the equations … Abstract Formulas for calculating relative permeability from pore size distribution data are derived from basic laws of fluid flow in porous media. The tortuosity factors that appear in the equations are described in terms of the physical properties of the medium and the saturations of the contained fluids. Procedures for calculating and methods for measuring the tortuosity factors are discussed. Values of relative permeability calculated by the formulas are compared with results obtained by experimental measurements. Introduction Recently, several investigators have derived relative permeability equations from Darcy's and Poiseuille's Laws in which some physical factor or factors describing the porous system appear. The factor that has caused the greatest amount of comment, and which is probably least understood, is the tortuosity of the fluid path in the porous sample. Values of the tortuosity factors appearing in the equations range from a constant for all conditions of the fluid flow system to an inverse function of the pore radii. It is the purpose of this paper to compare some experimentally determined relative permeability curves with those calculated by a method which utilized capillary pressure information. The capillary pressure data were obtained preferably from pore size distribution information as determined by mercury injection but, in some cases, in the absence of suitable mercury injection information, data were taken from measurements made by the porous semi-permeable diaphragm method. The physical significance of certain tortuosity concepts is inferred and the determinations of the tortuosity factors from pore size distribution data and by electrical measurements are discussed.

Diffusion of ions in sea water and in deep-sea sediments

1974-05-01

Yuanhui Li , Sandra Gregory

Fractal Sandstone Pores: Implications for Conductivity and Pore Formation

1985-03-25

A. J. Katz , A. H. Thompson

We use scanning electron microscopy and optical data to show that the pore spaces of several sandstones are fractal geometries and we use the fractal statistics to predict the correct … We use scanning electron microscopy and optical data to show that the pore spaces of several sandstones are fractal geometries and we use the fractal statistics to predict the correct porosity. Steady-state crystal growth during rock formation is a plausible cause of the self-similar geometry. The fractal-dimension values and a systematic analysis of rock conductivity data both mediate against percolation models as suitable models of rock pore-space geometry.

A two-dimensional nuclear Overhauser enhancement (2D NOE) experiment for the elucidation of complete proton-proton cross-relaxation networks in biological macromolecules

1980-07-01

Anil Kumar , Richard R. Ernst , Kurt Wüthrich

Investigation of complex networks of spin-spin coupling by two-dimensional NMR

1981-09-01

Ad Bax , Ray Freeman

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Temperature-dependent self-diffusion coefficients of water and six selected molecular liquids for calibration in accurate 1H NMR PFG measurements

2000-01-01

Manfred Holz , Stefan R. Heil , Antonio Sacco

Pulsed magnetic field gradient (PFG) NMR is today a routine method for the determination of self-diffusion coefficients, D. However, a remaining goal is the improvement of the precision of the … Pulsed magnetic field gradient (PFG) NMR is today a routine method for the determination of self-diffusion coefficients, D. However, a remaining goal is the improvement of the precision of the method. The best procedure for the determination of accurate diffusion coefficients by PFG NMR is a calibration with a sample of precisely known D-value. In continuation of our previous work on calibration at 25°C (M. Holz and H. Weingärtner, J. Magn. Reson., 1991, 92, 115) we present reference data as a function of temperature. Since H2O plays an outstanding role as liquid and as primary standard, we carefully measured self-diffusion coefficients of water by 1H PFG NMR in the temperature range from + 5 to + 55°C and added literature data obtained from tracer methods in the range between 0 and + 100°C. This comparatively large collection of data could then be fitted to a Speedy–Angell power law, showing the excellent congruence of the results of two completely different methods and proofing the certainty of the absolute values for water. In this manner reliable primary standard values with error limits of <1% were obtained, allowing us to adapt the temperature of the standard water to the sample temperature of interest. We further give 1H PFG NMR self-diffusion reference data in the range from + 5 to + 55°C for six easily accessible solvents, which we propose as secondary calibration standards, namely cyclohexane, dioxane, dodecane, DMSO, tetradecane and pentanol, covering a large range of absolute D-values and allowing us to match in addition the absolute D-values of calibration sample and sample under investigation. Furthermore, the gained accurate self-diffusion data are suited for an elaborate check of theoretical approaches in the physics of molecular liquids.

Molecular Models of Hydroxide, Oxyhydroxide, and Clay Phases and the Development of a General Force Field

2004-01-01

Randall T. Cygan , Jian-Jie Liang , Andrey G. Kalinichev

The fate of chemical and radioactive wastes in the environment is related to the ability of natural phases to attenuate and immobilize contaminants through chemical sorption and precipitation processes. Our … The fate of chemical and radioactive wastes in the environment is related to the ability of natural phases to attenuate and immobilize contaminants through chemical sorption and precipitation processes. Our understanding of these complex processes at the atomic level is provided by a few experimental and analytical methods such as X-ray absorption and NMR spectroscopies. However, due to complexities in the structure and composition of clay and other hydrated minerals, and the inherent uncertainties of the experimental methods, it is important to apply theoretical molecular models for a fundamental atomic-level understanding, interpretation, and prediction of these phenomena. In this effort, we have developed a general force field, CLAYFF, suitable for the simulation of hydrated and multicomponent mineral systems and their interfaces with aqueous solutions. Interatomic potentials were derived from parametrizations incorporating structural and spectroscopic data for a variety of simple hydrated compounds. A flexible SPC-based water model is used to describe the water and hydroxyl behavior. Metal−oxygen interactions are described by a Lennard-Jones function and a Coulombic term with partial charges derived by Mulliken and ESP analysis of DFT results. Bulk structures, relaxed surface structures, and intercalation processes are evaluated and compared to experimental and spectroscopic findings for validation. Our approach differs from most others in that we treat most interatomic interactions as nonbonded. This allows us to effectively use the force field for a wide variety of phases and to properly account for energy and momentum transfer between the fluid phase and the solid, while keeping the number of parameters small enough to allow modeling of relatively large and highly disordered systems. Simulations of clay, hydroxide, and oxyhydroxide phases and their interfaces with aqueous solutions combine energy minimization and molecular dynamics methods to describe the structure and behavior of water, hydroxyl, surface species, and intercalates in these systems. The results obtained to date demonstrate that CLAYFF shows good promise to evolve into a widely adaptable and broadly effective force field for molecular simulations of fluid interfaces with clays and other clay-related phases, as well as other inorganic materials characterized by complex, disordered, and often ill-determined structure and composition.

Application of Fourier Transform Spectroscopy to Magnetic Resonance

1966-01-01

Richard R. Ernst , W. A. Anderson

The application of a new Fourier transform technique to magnetic resonance spectroscopy is explored. The method consists of applying a sequence of short rf pulses to the sample to be … The application of a new Fourier transform technique to magnetic resonance spectroscopy is explored. The method consists of applying a sequence of short rf pulses to the sample to be investigated and Fourier-transforming the response of the system. The main advantages of this technique compared with the usual spectral sweep method are the much shorter time required to record a spectrum and the higher inherent sensitivity. It is shown theoretically and experimentally that it is possible to enhance the sensitivity of high resolution proton magnetic resonance spectroscopy in a restricted time up to a factor of ten or more. The time necessary to achieve the same sensitivity is a factor of 100 shorter than with conventional methods. The enhancement of the sensitivity is essentially given by the square root of the ratio of line width to total width of the spectrum. The method is of particular advantage for complicated high resolution spectra with much fine structure.

Fourier transform pulsed-gradient spin-echo studies of molecular diffusion

1987-01-01

Peter Stilbs

Investigation of exchange processes by two-dimensional NMR spectroscopy

1979-12-01

J. Jeener , Beat H. Meier , P. Bachmann +1 more

A new general technique for the investigation of exchange processes in molecular systems is proposed and demonstrated. Applications comprise the study of chemical exchange, of magnetization transfer by inter- and … A new general technique for the investigation of exchange processes in molecular systems is proposed and demonstrated. Applications comprise the study of chemical exchange, of magnetization transfer by inter- and intramolecular relaxation in liquids, and of spin diffusion and cross-relaxation processes in solids.

Modified Spin-Echo Method for Measuring Nuclear Relaxation Times

1958-08-01

S. Meiboom , Deepak Gill

A spin echo method adapted to the measurement of long nuclear relaxation times (T2) in liquids is described. The pulse sequence is identical to the one proposed by Carr and … A spin echo method adapted to the measurement of long nuclear relaxation times (T2) in liquids is described. The pulse sequence is identical to the one proposed by Carr and Purcell, but the rf of the successive pulses is coherent, and a phase shift of 90° is introduced in the first pulse. Very long T2 values can be measured without appreciable effect of diffusion.

Spin Diffusion Measurements: Spin Echoes in the Presence of a Time-Dependent Field Gradient

1965-01-01

E. O. Stejskal , J. E. Tanner

A derivation is given of the effect of a time-dependent magnetic field gradient on the spin-echo experiment, particularly in the presence of spin diffusion. There are several reasons for preferring … A derivation is given of the effect of a time-dependent magnetic field gradient on the spin-echo experiment, particularly in the presence of spin diffusion. There are several reasons for preferring certain kinds of time-dependent magnetic field gradients to the more usual steady gradient. If the gradient is reduced during the rf pulses, H1 need not be particularly large; if the gradient is small at the time of the echo, the echo will be broad and its amplitude easy to measure. Both of these relaxations of restrictions on the measurement of diffusion coefficients by the spin-echo technique serve to extend its range of applicability. Furthermore, a pulsed gradient can be recommended when it is critical to define the precise time period over which diffusion is being measured. The theoretical expression derived has been verified experimentally for several choices of time dependent magnetic field gradient. An apparatus is described suitable for the production of pulsed gradients with amplitudes as large as 100 G cm−1. The diffusion coefficient of dry glycerol at 26°±1°C has been found to be (2.5±0.2)×10−8 cm2 sec−1, a value smaller than can ordinarily be measured by the steady gradient method.

Tumor Detection by Nuclear Magnetic Resonance

1971-03-19

R Damadian

Spin echo nuclear magnetic resonance measurements may be used as a method for discriminating between malignant tumors and normal tissue. Measurements of spin-lattice (T(1)) and spin-spin (T(2)) magnetic relaxation times … Spin echo nuclear magnetic resonance measurements may be used as a method for discriminating between malignant tumors and normal tissue. Measurements of spin-lattice (T(1)) and spin-spin (T(2)) magnetic relaxation times were made in six normal tissues in the rat (muscle, kidney, stomach, intestine, brain, and liver) and in two malignant solid tumors, Walker sarcoma and Novikoff hepatoma. Relaxation times for the two malignant tumors were distinctly outside the range of values for the normal tissues studied, an indication that the malignant tissues were characterized by an increase in the motional freedom of tissue water molecules. The possibility of using magnetic relaxation methods for rapid discrimination between benign and malignant surgical specimens has also been considered. Spin-lattice relaxation times for two benign fibroadenomas were distinct from those for both malignant tissues and were the same as those of muscle.

Coherent Averaging Effects in Magnetic Resonance

1968-11-10

U. Haeberlen , J. S. Waugh

A theory is developed to describe the slow component of the transient decay of transverse spin magnetization, and the central component of the slow-passage absorption spectrum, of a system of … A theory is developed to describe the slow component of the transient decay of transverse spin magnetization, and the central component of the slow-passage absorption spectrum, of a system of spins which is subjected to a periodic and cyclic perturbation. The theory is used to analyze and compare various schemes for high-resolution NMR of solids, including the spinning of the sample about an axis oriented at the "magic angle," the rotating-frame magic-angle experiment of Lee and Goldburg, pulsed versions of the latter, and a number of new pulsed-NMR experiments recently developed in this laboratory. Attention is focused on the factors, both theoretical and practical, which are important in obtaining optimal suppression of static dipole-dipole interactions and quadrupole splittings, and retention of chemical and Knight shifts and scalar spin-spin interactions. Several new experiments are proposed.

NMR Studies of Cyclodextrins and Cyclodextrin Complexes

1998-07-11

Hans‐Jörg Schneider , Frank Hacket , Volker Rüdiger +1 more

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNMR Studies of Cyclodextrins and Cyclodextrin ComplexesHans-Jörg Schneider, Frank Hacket, Volker Rüdiger, and Hiroshi IkedaView Author Information FR Organische Chemie der Universität des Saarlandes, D 66041 Saarbrücken, … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNMR Studies of Cyclodextrins and Cyclodextrin ComplexesHans-Jörg Schneider, Frank Hacket, Volker Rüdiger, and Hiroshi IkedaView Author Information FR Organische Chemie der Universität des Saarlandes, D 66041 Saarbrücken, Germany Department of Bioengineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226, Japan Cite this: Chem. Rev. 1998, 98, 5, 1755–1786Publication Date (Web):July 11, 1998Publication History Received10 November 1997Revised26 May 1998Published online11 July 1998Published inissue 30 July 1998https://pubs.acs.org/doi/10.1021/cr970019thttps://doi.org/10.1021/cr970019tresearch-articleACS PublicationsCopyright © 1998 American Chemical SocietyRequest reuse permissionsArticle Views19086Altmetric-Citations1296LEARN 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 InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Carbohydrates,Cavities,Macrocyclic compounds,Nuclear magnetic resonance spectroscopy,Oligosaccharides Get e-Alerts

Measurement ofJand Dipolar Couplings from Simplified Two-Dimensional NMR Spectra

1998-04-01

Marcel Ottiger , Frank Delaglio , Ad Bax

Product operator formalism for the description of NMR pulse experiments

1984-01-01

Ole W. Sørensen , G.W. Eich , Malcolm H. Levitt +2 more

Diffusion NMR Spectroscopy in Supramolecular and Combinatorial Chemistry: An Old Parameter—New Insights

2004-12-30

Yoram Cohen , Liat Avram , Limor Frish

Intermolecular interactions in solution play an important role in molecular recognition, which lies at the heart of supramolecular and combinatorial chemistry. Diffusion NMR spectroscopy gives information over such interactions and … Intermolecular interactions in solution play an important role in molecular recognition, which lies at the heart of supramolecular and combinatorial chemistry. Diffusion NMR spectroscopy gives information over such interactions and has become the method of choice for simultaneously measuring diffusion coefficients of multicomponent systems. The diffusion coefficient reflects the effective size and shape of a molecular species. Applications of this technique include the estimation of association constants and mapping the intermolecular interactions in multicomponent systems as well as investigating aggregation, ion pairing, encapsulation, and the size and structure of labile systems. Diffusion NMR spectroscopy can also be used to virtually separate mixtures and screen for specific ligands of different receptors, and may assist in finding lead compounds.

Cohesion of Ionic Solids in the Born Model

1964-01-01

Mario P. Tosi

NMR Basic principles and progress

1973-02-01

Aksel A. Bothner

Protein NMR Spectroscopy. Principles and Practice

1997-01-01

Hans Robert Kalbitzer

Carbon-13 NMR spectroscopy

1987-09-01

John B. Grutzner

Hydrodynamic and Hydromagnetic Stability

2001-09-01

Principles of magnetic resonance

1990-01-01

Diffusion ordered nuclear magnetic resonance spectroscopy: principles and applications

1999-05-01

Charles S. Johnson

Carbon-13 NMR Spectroscopy

1972-01-01

J. B. Stothers

The signal-to-noise ratio of the nuclear magnetic resonance experiment

1976-10-01

D. I. Hoult , R. E. Richards

NMR - Basic Principles and Progress

1972-02-01

Spectral Methods

2006-01-01

Claudio Canuto , M. Y. Hussaini , Alfio Quarteroni +1 more

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Dynamic NMR Spectroscopy

1983-11-01

I G.C.

Encyclopedia of nuclear magnetic resonance

1997-06-01

Mathematical description of the magnetohydrodynamic displacement principle of electrically conductive oily liquids

2025-06-24

Igor Yurievich Aleksanyan , Ilgam Zaurovich Isanaliev , Roman Ravilevich Sultanov +1 more | Oil and gas technologies and environmental safety

The magnetohydrodynamic principle is an important interdisciplinary field. In modern conditions of development of the technical design of oil extraction, there is a need for magnetohydrodynamic equipment that allows automating … The magnetohydrodynamic principle is an important interdisciplinary field. In modern conditions of development of the technical design of oil extraction, there is a need for magnetohydrodynamic equipment that allows automating complex processes in oil product extraction technology and increasing their degree of mechanization, as well as saving energy and resources while increasing environmental safety. One of the most important applications of this effect is the pumping of materials, which is currently carried out by conventional low-efficiency pumping units. To solve the problem of increasing the efficiency of the indicated operation using magnetohydrodynamic technology, it is advisable to use modeling, which makes it possible to replace the original with its mathematical counterpart. Due to the complexity of the analyzed operations, the indicated devices consider only substantially idealized model schemes that are not acceptable for studying their statics and dynamics, as well as the synthesis of automatic control complexes, which determines the relevance of constructing a model that corresponds to the physical control mechanism of the studied objects. The article de-scribes in detail the physical principle of operation of MHD devices based on the interaction of an electric current passed through an electrically conductive liquid (in this case, a watered reservoir fluid, which is an electrolyte) and a high-intensity magnetic field perpendicular to it. The Lorentz force resulting from this interaction and leading to fluid displacement is described. The design scheme of the MHD pump is presented and its main advantages (compactness, thermal stability, absence of moving elements, reliability, relatively high efficiency (UAC), short transient time interval, low maintenance, ease of operation at the microlevel, high specific power) and disadvantages (problems of superconducting technologies, edge effects of the magnetic field, bulky dimensions) are considered. magnetic elements, lack of correct analytical models, uneven velocity profile and flow instability).

History of NMR in India

2025-06-24

R.V Hosur | Magnetic Resonance in Chemistry

ABSTRACT Documentation of the historical developments plays a vital role in recognising the pioneering contributions by the scientists of the previous generations. As we progress, there is a high chance … ABSTRACT Documentation of the historical developments plays a vital role in recognising the pioneering contributions by the scientists of the previous generations. As we progress, there is a high chance of missing out on those contributions. In this special issue which is devoted to recounting the contributions of Indian scientists in the area of magnetic resonance, the present article is an effort to put on record the invaluable contributions by the previous generations which have indeed been quite substantial. It is an effort which is certainly not exhaustive, but a sincere effort has been made to be as inclusive as possible. The article focuses mostly on Nuclear Magnetic Resonance (NMR). It is also not a document to highlight the contributions of the present generations, since the individual scientists of the present era will be writing separate articles focusing on their own achievements, in this special issue. Moreover, I may not be doing justice to their contents, on one hand, and may run the risk of bias of inclusion on the other.

Displacement field visualization of particle beds after slow impacts using diffusing wave spectroscopy

2025-06-23

NULL AUTHOR_ID | Physical review. E

NMR Relaxation of a Liquid in Unsaturated and Dual-Porous Systems: Combined Visualized Micromodel and NMR Measurement

2025-06-23

Jinhao Sun , Peixue Jiang , Ruina Xu | The Journal of Physical Chemistry Letters

NMR relaxometry is widely applied in natural and industrial fields for fluid characterization in porous materials. However, NMR relaxation time T2 in complex porous systems is effected by liquid-gas interfaces … NMR relaxometry is widely applied in natural and industrial fields for fluid characterization in porous materials. However, NMR relaxation time T2 in complex porous systems is effected by liquid-gas interfaces and interpore interactions significantly, introducing ambiguity into the interpretation of NMR measurements. Here, we extend NMR relaxometry applications to unsaturated and dual-porous systems with micro- and nanoscale pores by quantitatively clarifying the influence of liquid saturation and dual-porous features on T2 spectra through theoretical analysis, experiments, and simulations. A novel experimental method integrating visualized micromodels with NMR measurement is proposed to directly link the pore-scale fluid morphology with T2 spectra, establishing a quantitative relationship between T2 and liquid saturation in pores. We reveal that the increasing microscale pore size leads to a change from unimodal to bimodal T2 spectrum for liquid in dual-porous system, and the overall dual-porous liquid saturation can be predicted well from the established relationship. Our findings provide a basis for accurately analyzing liquid behavior in complex porous systems using NMR measurements, which is crucial for advancing the understanding of multiphase phenomena in porous materials.

Lithium ion dynamics in synthetic quartz studied via the NMR of implanted <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi/><mml:mn>8</mml:mn></mml:msup></mml:math> Li <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi/><mml:mo>+</mml:mo></mml:msup></mml:math>

2025-06-23

NULL AUTHOR_ID | Physical review. B./Physical review. B

Magnetic resonance imaging

2025-06-20

Soumyajit Mandal | Elsevier eBooks

Analysis of Proton NMR Transverse Magnetization Decay of Mixtures of Compounds and Semicrystalline Polymers: A Least-Squares Fit and the Inverse Laplace Transform

2025-06-20

Radu Fechete , V. M. Litvinov | The Journal of Physical Chemistry B

The present study aimed to determine the strategy for analysis of NMR transverse magnetization decay (the T2 decay) of semicrystalline polymers using two alternative methods, i.e., a least-squares fit of … The present study aimed to determine the strategy for analysis of NMR transverse magnetization decay (the T2 decay) of semicrystalline polymers using two alternative methods, i.e., a least-squares fit of decays and their inverse Laplace transform (ILT). First, these methods are used to analyze the T2 decay of one-phase compounds with physical states ranging from crystals (gypsum) to glassy polymer (polycarbonate, PC) and from amorphous EPDM vulcanizate to melts of PC and high-density polyethylene. Then, physical mixtures of these compounds are analyzed. Finally, the T2 decay of isotactic polypropylene and propylene-ethylene random copolymers with complex physical structures is examined. For the study, a kernel of commonly used ILT software, which is applicable for the analysis of exponential functions, was modified by adding the Gaussian and the Abragamian functions that describe well the decay shape of glassy and crystalline compounds, respectively. To our knowledge, such a composite kernel has not been used before. This method was named the Laplace-like. The Laplace-like analysis offers advantages when the decay rate of different phases does not largely differ, e.g., in materials composed of crystals, glassy phases, and interfaces with restricted molecular mobility when deconvolution of T2 decays with a least-squares method fails. The Laplace-like method can help to identify the number of polymer fractions with restricted chain mobility and distribution of specific (exponential, Gaussian, or Abragamian) T2 relaxation times. However, the ILT method with the exponential kernel cannot provide meaningful data for soft polymeric matters. The reliable analysis requires implementation in the kernel of the Laplace algorithm complex functions describing the shape of NMR decays of soft polymeric matters and polymer melts. The advantages and limitations of a least-squares deconvolution of T2 decays into their components and the Laplace-like method are discussed. The most reliable procedures for extracting information about the phase composition and molecular mobility in different phases of semicrystalline polymers were proposed.

New approaches in reservoir characterization utilizing conventional and special core analyses: a comprehensive review

2025-06-19

Bassem S. Nabawy | Journal of Umm Al-Qura University for Applied Sciences

Abstract Petrophysics deals mostly with evaluating the reservoir rocks and assessment the pore volume and its connectivity as well as type of fluid content and saturation. It is a very … Abstract Petrophysics deals mostly with evaluating the reservoir rocks and assessment the pore volume and its connectivity as well as type of fluid content and saturation. It is a very important trend acting as a link between the geological and reservoir engineering studies as well as help in calibrating and improving results of the geophysical studies. It is mostly subdivided into two sub-trends, well logging and core analyses that help greatly in constructing the static model for a given reservoir in integration with the petrography and seismic studies. The field of petrophysics has been developed greatly during the last decades achieving a precise evaluation and matching of the pore spaces in 3-D using many advanced techniques. For the development of the well logging tools, more detailed fractures characterization and accurate permeability measurements have been achieved down hole; whereas for the core analyses, a more precise pore spaces characterization and reservoir simulation in the Laboratory have been improves using the advanced techniques. The new achievements in the core analyses include foundation of new techniques and concepts as (1) pore fabric assignment in 3-D considering the anisotropy of magnetic susceptibility ‘AMS’ in 3-D, spatial anisotropy of the formation resistivity factor measured in 54 directions to calculate the electric pore fabric, and the anisotropy of permeability, (2) Reservoir quality discrimination and reservoir zonation into conductive, super conductive and non-conductive zones, (3) Electric print to estimate the impact of the presence and percentage of some important elements as the Ni content in meteorites, and TOC in coal samples by measuring the electric resistivity of their samples at different frequencies (1 Hz–8.0 MHz), (4) Accurate Archie’s parameters estimation, (5) Pore throat characterization using MICP tests (mercury injection capillary pressure), (6) Wettability using Amott index, (7) Relative permeability as a tool for characterizing the reservoir and fluids properties in a given sequence, (8) Computed tomography X-ray (CT Scan) for detecting the fractures and capillarity of rocks, and (9) Nuclear magnetic resonance (NMR) for estimating porosity, bound water, permeability, and shale volume. Indeed, petrophysical core analyses data are the most recent and advanced tools for getting a precise reservoir characterization.

Tempera paint solidification followed by single-sided NMR: An egg-cellent article that will dry you up

2025-06-19

Floriane Gerony , Côme Thillaye du Boullay , Laurence de Viguerie +7 more | Progress in Organic Coatings

NMR Relaxometry Across Time: From Early Insights to Emerging Directions

2025-06-19

Pellegrino Conte , David A. Faux , Anne‐Laure Rollet +4 more | Magnetic Resonance in Chemistry

ABSTRACT Nuclear magnetic resonance (NMR) relaxometry has evolved from early theoretical insights into a dynamic and versatile analytical technique capable of probing molecular and ionic motion across diverse fields. Rooted … ABSTRACT Nuclear magnetic resonance (NMR) relaxometry has evolved from early theoretical insights into a dynamic and versatile analytical technique capable of probing molecular and ionic motion across diverse fields. Rooted in the foundational work by many different scientists (e.g., Bloch, Purcell, Torrey, Hahn, Bloembergen, Pound, and Solomon, just to name a few), relaxometry has progressed through pivotal advancements such as Redfield's theory and the development of time‐domain (TD) and fast field‐cycling (FFC) methodologies. While the former enables rapid, low‐cost analysis of relaxation time distributions, widely applied in soft matter and quality control, the latter provides frequency‐resolved nuclear magnetic resonance dispersion (NMRD) profiles that capture dynamic processes across multiple timescales, revealing deeper insights into molecular interactions in heterogeneous systems. Recent innovations in instrumentation have expanded the applicability of relaxometry. Moreover, its integration with modalities such as diffusimetry and imaging has opened new routes for spatially resolved and multimodal analyses. Applications now span materials science, biomedicine, and environmental studies. In polymers and porous media, relaxometry reveals segmental dynamics and surface interactions; in biological tissues, NMRD profiles differentiate healthy from pathological states, offering diagnostic potential. Emerging applications include contrast agent development, soil hydration analysis, microplastic detection, and wastewater monitoring. This paper offers a comprehensive overview of the field's historical trajectory, methodological advancements, and expanding application landscape. Emphasis is placed on the synergy between TD and FFC‐NMR approaches and the ongoing transition toward portable, real‐time, and multimodal relaxometric systems. NMR relaxometry is poised to become a mainstream tool in diagnostics, materials characterization, and environmental monitoring.

Reverse Curve Fitting Approach for Quantitative Deconvolution of Closely Overlapping Triplets in Fourier Transform Nuclear Magnetic Resonance Spectroscopy Using Odd-Order Derivatives

2025-06-17

Shuping Chen , Sandra M. Taylor , Sai Huang +1 more | Magnetochemistry

A new deconvolution strategy, reverse curve fitting, was developed to determine peak positions and independent intensities of overlapping Fourier transform (FT) nuclear magnetic resonance (NMR) bands. From the third-order derivative … A new deconvolution strategy, reverse curve fitting, was developed to determine peak positions and independent intensities of overlapping Fourier transform (FT) nuclear magnetic resonance (NMR) bands. From the third-order derivative of the overlapping band, the peak position was estimated from its zero-crossing point and the peak intensity was quantitated by partial curve matching with its primary maxima. Every matched peak in the overlapping band was dismembered in turn to weaken the overlap until an independent peak was filtered out. The deconvolution can be refined progressively by manually tuning the peak positions and peak widths. In a simulation study, a closely overlapped 13C NMR triplet (overlapping degrees between 0.5 and 1.0) at a signal-to-noise ratio (SNR) of 20:1 was quantitatively deconvoluted by our reverse curve fitting procedure with a routine denoising technique. The noise interference and denoising technique were also studied in the simulation. A real FT-NMR overlapping band of Ethylbenzene (300 MHz) was satisfactorily deconvoluted and compatible with higher resolution literature spectral data. A more complicated overlapping NMR band of Tetraphenyl porphyrin was studied as well. This new approach to the deconvolutions is applicable to other FT spectroscopies.

Out on a Limb: The Signatures of East–West Asymmetries in Transmission Spectra from General Circulation Models

2025-06-17

Kenneth E. Arnold , Arjun B. Savel , Eliza M.-R. Kempton +5 more | The Astrophysical Journal

Abstract In the era of JWST, observations of hot Jupiter atmospheres are becoming increasingly precise. As a result, the signatures of limb asymmetries due to temperature or abundance differences and … Abstract In the era of JWST, observations of hot Jupiter atmospheres are becoming increasingly precise. As a result, the signatures of limb asymmetries due to temperature or abundance differences and the presence of aerosols can now be directly measured using transmission spectroscopy. Using a grid of general circulation models with varying irradiation temperatures (1500–4000 K) and prescriptions of cloud formation, we simulate 3D ingress/egress and morning-/evening-limb transmission spectra. We aim to assess the impact that clouds, 3D temperature structure, and nonuniform distribution of gases have on the observed spectra, and how these inhomogeneities can be identified. A second goal is to assess the relative merits of two separate methods (ingress/egress versus morning-/evening-limb spectroscopy) for isolating atmospheric asymmetries. From our models, it is evident that an east–west temperature difference is the leading-order effect for producing ingress/egress or morning-/evening-limb spectral differences. We additionally find that clouds contribute strongly to the observed limb asymmetry at moderate irradiation temperatures in our grid (∼2000 K < T irr < 3500 K). At lower temperatures clouds equally dominate the optical depth on both limbs, while at higher temperatures the entire terminator region remains cloud free. We develop limb asymmetry metrics that can be used to assess the degree of east–west asymmetry for a given planet and predict trends in these metrics with respect to irradiation temperature that are indicative of various physical processes. Our results are useful for predicting and diagnosing the signatures of limb asymmetries in JWST spectra.

Fluid flow characteristics in porous media using Magnetic Resonance Imaging (MRI) technique: Determining the capillary pressure and relative permeability

2025-06-16

Kourosh Mohammadi , Ali Esfandiarian , Jaber Taheri-Shakib | Advances in Colloid and Interface Science

Adding the AMBER 14SB Force Field to the Stochastic Titration CpHMD Method

2025-06-16

João G. N. Sequeira , Adrián E. Roitberg , Miguel Machuqueiro | Journal of Chemical Theory and Computation

Incorporating pH into molecular dynamics simulations is vital for accurately capturing the fully coupled conformational, energetic, and protonation landscape of many systems. The constant-pH molecular dynamics (CpHMD) methodologies represent state-of-the-art … Incorporating pH into molecular dynamics simulations is vital for accurately capturing the fully coupled conformational, energetic, and protonation landscape of many systems. The constant-pH molecular dynamics (CpHMD) methodologies represent state-of-the-art approaches to achieve this, with stochastic titration CpHMD (st-CpHMD) currently being one of the most well-developed and validated methods. St-CpHMD is already compatible with both the GROMOS 54A7 and CHARMM 36m force fields, and we extend it here to support the AMBER 14SB force field available in the GROMACS software package. We introduce and validate a minor modification to the official atomic partial charges of ff14SB (to achieve neutralization of the main chain) to render them compatible with st-CpHMD, and we benchmark the final implementation using lysozyme and Staphylococcal nuclease proteins. Although the root-mean-square error (RMSE) values of the predictions for pKa versus experimental data align closely with those obtained using the other supported force fields, we also identified several challenging cases where the method requires further improvement. AMBER 14SB simulations showed a lower computational cost compared to CHARMM 36m, despite being slightly higher than the GROMOS 54A7 simulations. Our findings also indicate that to further enhance computational speed, future efforts should concentrate on accelerating the PB/MC step. With this extension, we have developed the first CpHMD method implementation compatible with the three most widely used protein force fields, enabling, for the first time, a direct performance comparison among them.

Viscosity Prediction of Water-Containing Hydraulic Oil in the Deep-Sea Environment Using Molecular Dynamics Simulations

2025-06-16

Mingjun Shen , Yinshui Liu , Xinping Zhou | Journal of Chemical & Engineering Data

Dynamics of Supramolecular Ionic Gels by Means of Nuclear Magnetic Resonance Relaxometry—The Case of [BMIM][Cl]/Propylene Carbonate Gel

2025-06-15

Michał Bielejewski , Robert Kruk , Danuta Kruk | Molecules

Aiming to obtain insight into the dynamic properties of ionogels, 1H NMR relaxation experiments were performed for an ionogel composed of 1-butyl-3-methyl-imidazolium chloride [BMIM][Cl] and propylene carbonate. The experiments were … Aiming to obtain insight into the dynamic properties of ionogels, 1H NMR relaxation experiments were performed for an ionogel composed of 1-butyl-3-methyl-imidazolium chloride [BMIM][Cl] and propylene carbonate. The experiments were conducted in the frequency range of 10 kHz to 20 MHz, spanning the temperature range of 273 K to 338 K. The data were analyzed in term s of a relaxation model including two relaxation contributions-one of them associated with anisotropic (two-dimensional) translation diffusion, the second one representing a power law dependence of spin-lattice relaxation rates on the resonance frequency. The power law relaxation term (characterized by a very low power law factor of about 0.1) was attributed to the collective dynamics of the partially immobilized propylene carbonate matrix, while the relaxation contribution associated with anisotropic translation diffusion was attributed to the movement of BMIM cations in the matrix; the translation diffusion coefficient was estimated as varying in the range of 10-13 m2/s-10-12 m2/s. Moreover, other parameters were determined as a result of the analysis, such as the residence lifetime on the matrix surfaces. Subsequently, the temperature dependencies of the determined parameters were assessed.

Extracting Trends From NMR Data With TrAGICo: A Python Toolbox

2025-06-12

Letizia Fiorucci , F. Bruno , Leonardo Querci +7 more | Magnetic Resonance in Chemistry

ABSTRACT In this tutorial, we present TrAGICo (Trends Analysis Guided Interfaces Collection), a Python collection of functions for the extraction and analysis of experimental parameters from 1D and pseudo‐2D NMR … ABSTRACT In this tutorial, we present TrAGICo (Trends Analysis Guided Interfaces Collection), a Python collection of functions for the extraction and analysis of experimental parameters from 1D and pseudo‐2D NMR spectra acquired on Bruker instruments. We demonstrate the application of TrAGICo through practical examples, highlighting its utility for various NMR applications, such as extraction of the chemical shift temperature dependence, relaxation studies, and reaction monitoring.

Magnetic-resonance-relaxation studies of fluid-saturated model porous-glass systems: The influence of pore size

2025-06-09

NULL AUTHOR_ID | Physical Review Applied

Distinguishing Rock Fracture and Pore's T2 Signals From NMR Experiments With Assisted X‐Ray CT Imaging

2025-06-02

Ying Yang , Limin Li , Tianlin Wen +4 more | Energy Science & Engineering

ABSTRACT Nuclear magnetic resonance (NMR) is widely used to characterize fluids in rock pore spaces, but traditional methods have difficulty distinguishing fractures from matrix pores in complex carbonate formations. To … ABSTRACT Nuclear magnetic resonance (NMR) is widely used to characterize fluids in rock pore spaces, but traditional methods have difficulty distinguishing fractures from matrix pores in complex carbonate formations. To address this, we developed a calibration method that integrates X‐ray computed tomography (CT) imaging with NMR to identify fracture‐related T 2 signals. The method quantitatively calibrates NMR T 2 spectra to fracture aperture sizes, improving the accuracy of fracture characterization. Fully saturated fractured samples were used, and fracture fluids were progressively removed using gas displacement techniques. NMR spectra were recorded before and after fluid removal to isolate fracture‐specific signals. Fracture size distributions were estimated from CT images by pixel counting, and porosity was determined by fluid saturation measurements, with corrections for matrix porosity not captured by CT resolution. This workflow extracts fracture distributions from T 2 spectra and establishes a correlation between pore radius ( r ) and T 2 , enabling subsequent applications in core analysis and NMR logging. The method improves differentiation between fractures and matrix pores, enhances the interpretation of NMR data, and can be adapted to heterogeneous reservoir systems.

Pore-scale drying kinetics of white cement mortars through the LF-NMR relaxation technique

2025-06-01

Hanxue Liang , Yun Zhang , Sihui Luo +2 more | Journal of Building Engineering

A mathematical model of NMR transverse relaxation for pore size distribution estimation in porous media

2025-06-01

S. Morales-Chávez , Miguel A. Valdez‐Grijalva , Martín A. Díaz-Viera +2 more | Journal of Magnetic Resonance

Insight into the Effect of pH on Component Structure and Dynamics in Glycerol–Water Mixture from NMR and Molecular Dynamics Simulations

2025-06-01

Kirthi Joshi , Satyam Singh , Manju Sharma +1 more | ChemistrySelect

Abstract NMR experiments and molecular dynamics simulations have been performed to study the assemblage of the components in a binary mixture of glycerol and water by systematically varying the glycerol … Abstract NMR experiments and molecular dynamics simulations have been performed to study the assemblage of the components in a binary mixture of glycerol and water by systematically varying the glycerol content and the pH (acidity) of the medium. NMR studies show that chemical shifts of glycerol alkyl protons move upfield (low‐frequency shift or shielding) and water protons move downfield (high‐frequency shift or deshielding). Molecular dynamics studies provide evidence for an increase in CH─OH interactions between glycerol molecules, an increase in cluster size of glycerol, and spatial localization of water with an increase in glycerol concentration or a decrease in the pH (from neutral to acidic, pK a ∼ 5) of the medium for a given concentration of glycerol. The intra‐ and intercomponent interaction energies vary systematically with glycerol concentration across the pH scale. Translational diffusion of clusters suggests that the average size of the dynamic clusters of glycerol increases from 2 to 8 monomers as the glycerol level in the binary mixture is raised from ∼ 5% to 60%, irrespective of the medium acidity. The preferential interactions of glycerol and water are explained by invoking the concept of composition fluctuation.

Quantitative characterization of oil–water occurrence states in organic-rich, high-clay, and multi-lithofacies shale reservoirs using vacuum-imbibition and two-dimensional nuclear magnetic resonance

2025-06-01

Xiaobo Guo , Qian Sang , Mingzhe Dong +3 more | Physics of Fluids

Quantitative characterization of oil–water occurrence states is of great significance to the evaluation of shale oil mobility and the selection of sweet spot. Chang 73 shale reservoir is characterized by … Quantitative characterization of oil–water occurrence states is of great significance to the evaluation of shale oil mobility and the selection of sweet spot. Chang 73 shale reservoir is characterized by organic-rich, high-clay contents and multi-lithofacies, which makes the fluid distribution and occurrence state characterization more complicated than conventional reservoirs. In this paper, the organic/inorganic porosity and saturation with different lithofacies were characterized by vacuum-imbibition experiment. Then, considering the adsorption of clay minerals and kerogen to shale oil, two-dimensional nuclear magnetic resonance (2D NMR) maps of each hydrogen-bearing component of three different lithofacies were established. Based on vacuum-imbibition combined with 2D NMR, a new method for calculating the contents of fluid occurrence states was proposed. The results indicate that lenticular laminated shale (LLS) and horizontal laminated shale (HLS) have higher TOC (total organic carbon) content, which results in organic porosity being greater than that of massive mudstone (MM). However, MM has a higher clay content, which leads to its inorganic porosity being higher than that of HLS and LLS. From the T1-T2 spectra, HLS and LLS are primarily composed of movable oil and movable water, while MM is mainly composed of kerogen adsorbed oil and movable water. Ad/absorbed oil content is positively correlated with TOC and clay content. High TOC and low clay content can reduce the amounts of bound water and adsorbed water, promoting the mobilization of movable oil.

Unravelling the Surface Local Spin Dynamics in Magnetic Nanoparticles by Means of NMR Relaxometry

2025-05-29

Martina Basini , Manuel Mariani , Quoc Lam Vuong +5 more | Physical Review Letters

We singled out the surface and bulk spin dynamics in magnetic hollow nanoparticles by means of nuclear magnetic resonance relaxometry. Experimental <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mmultiscripts><a:mrow><a:mi mathvariant="normal">H</a:mi></a:mrow><a:mprescripts/><a:none/><a:mrow><a:mn>1</a:mn></a:mrow></a:mmultiscripts><a:mtext>−</a:mtext><a:mi>NMR</a:mi></a:mrow></a:math>-dispersion curves (NMR-D), measured across a … We singled out the surface and bulk spin dynamics in magnetic hollow nanoparticles by means of nuclear magnetic resonance relaxometry. Experimental <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mmultiscripts><a:mrow><a:mi mathvariant="normal">H</a:mi></a:mrow><a:mprescripts/><a:none/><a:mrow><a:mn>1</a:mn></a:mrow></a:mmultiscripts><a:mtext>−</a:mtext><a:mi>NMR</a:mi></a:mrow></a:math>-dispersion curves (NMR-D), measured across a wide frequency range (<d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mrow><d:msup><d:mrow><d:mn>10</d:mn></d:mrow><d:mrow><d:mn>4</d:mn></d:mrow></d:msup><d:mtext> </d:mtext><d:mtext> </d:mtext><d:mi>Hz</d:mi><d:mo><</d:mo><d:mi>f</d:mi><d:mo><</d:mo><d:mn>3</d:mn><d:mo>×</d:mo><d:msup><d:mrow><d:mn>10</d:mn></d:mrow><d:mrow><d:mn>8</d:mn></d:mrow></d:msup><d:mtext> </d:mtext><d:mtext> </d:mtext><d:mi>Hz</d:mi></d:mrow></d:math>), show the presence of a high-frequency contribution to the longitudinal relaxation rate, evidenced for the first time and ascribed to the surface spin dynamics. The nuclear longitudinal relaxation rates were successfully analyzed by means of a phenomenological model accounting for the two spin populations, i.e., surface and core spins. The fit of the longitudinal NMR-D data by means of this model allowed for the estimation of the hyperfine coupling constant of the surface spins, and of the superparamagnetic <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mrow><f:mn>1</f:mn><f:mo>/</f:mo><f:msub><f:mi>τ</f:mi><f:mi>N</f:mi></f:msub></f:mrow></f:math> and surface-paramagnetic-like <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:mrow><h:mn>1</h:mn><h:mo>/</h:mo><h:msubsup><h:mrow><h:mi>τ</h:mi></h:mrow><h:mrow><h:mi>C</h:mi></h:mrow><h:mrow><h:mi>surf</h:mi></h:mrow></h:msubsup></h:mrow></h:math> spin-spin correlation frequency, the last one being larger by more than 1 order of magnitude. These experimental results provide a substantial contribution to the basic knowledge of spin dynamics in nanoscale systems. Published by the American Physical Society 2025

Cation-Driven Modulation of Tau Condensates: Insights into Liquid–Liquid Phase Separation and Rheological Properties

2025-05-29

Nahuel N. Foressi , Leandro Cruz Rodríguez , Natalia Wilke +1 more | Biomacromolecules

The formation of biocondensates through liquid-liquid phase separation (LLPS) has emerged as a vital and ubiquitous phenomenon contributing to the spatiotemporal coordination of cellular processes. Additionally, dysregulation of LLPS is … The formation of biocondensates through liquid-liquid phase separation (LLPS) has emerged as a vital and ubiquitous phenomenon contributing to the spatiotemporal coordination of cellular processes. Additionally, dysregulation of LLPS is increasingly implicated as a previously overlooked driver of diseases. LLPS typically involves multivalent noncovalent interactions among biomolecules, yet the role of solvent molecules, particularly water, in this process has received increasing attention. Metal ions are essential for life and exist in varying concentrations within cells. Both the concentration and type of metal ions significantly influence the phase separation of biomolecules. Ions with different degrees of hydration can uniquely alter the structure of water, which, in turn, affects LLPS. In this study, we use hyperspectral imaging (HSI) analysis and optical tweezers to investigate the effects of cations with different degrees of hydration on solvent properties within Tau condensates, an intrinsically disordered protein involved in Alzheimer's disease. We first demonstrate that the environment within Tau droplets is more structured than the diluted phase. Then, we show that highly hydrated cations enhance phase separation, increase the proportion of restricted water within Tau droplets, and slow down their relaxation dynamics, suggesting a correlation between water structuring and rheological properties. By connecting solvent properties with the stability and dynamics of phase-separated droplets, this research provides insights into the molecular mechanisms governing LLPS and how environmental factors, such as metal ions and water structure, influence this process.

Global sensitivity analysis of a hydrogeophysical model coupling groundwater infiltration process and Surface Nuclear Magnetic Resonance

2025-05-28

Guillaume Gru , Jean‐François Girard , Philippe Ackerer +1 more | ARPHA Conference Abstracts

1: Introduction Water resources in mountainous areas are of major importance for local ecosystems as well as for human activities. Therefore, it is crucial to monitor the availability of these … 1: Introduction Water resources in mountainous areas are of major importance for local ecosystems as well as for human activities. Therefore, it is crucial to monitor the availability of these resources and to be able to predict their evolution accurately in the context of climate change. Hydrologic modeling is a useful tool to achieve this goal. To do so, the models need to be properly parameterized. Geophysical sounding techniques are very useful tools to provide information for the model calibration process. This work focuses on the Surface Nuclear Magnetic Resonance (SNMR) sounding technique. This geophysical method is based on nuclear magnetic resonance and has the advantages of being non-destructive and directly sensitive to the groundwater content (Legchenko and Valla 2002). A time-lapse SNMR survey was conducted in the Strengbach headwater catchment in the Vosges Mountains (France) during the winter 2021 with the aim of following an infiltration event. Before using this data set for hydrologic model calibration, we used Global Sensitivity Analysis (GSA) tools in order to determine which hydrologic parameters were most influential on the geophysical sounding outputs. This first step is useful for estimating parameters' identifiability. 2: Study site The study site of interest for this time-lapse SNMR experiment is the Strengbach experimental catchment. It is a small forested water catchment located in the Vosges Mountains (Northeast of France, Fig. 1). This catchment hosts the Observatoire Hydro-Géochimique de l'Environnement (OHGE): a long-term observatory where meteorological, hydrological and geochemical data have been measured since 1986. The OHGE is part of the French critical zone observatories network OZCAR. The main purpose of this observatory is to study long-term modifications of ecosystems under natural and anthropogenic pressures (Pierret et al. 2018). 3: SNMR method and hydrogeophysical model SNMR is a geophysical sounding technique based on nuclear magnetic resonance: an energizing electric pulse is generated in a wire loop at the ground surface. This pulse induces an electromagnetic field that triggers the protons from the hydrogen atoms in the groundwater molecules. After the perturbing electromagnetic field is shut down, one can observe a relaxation electromagnetic field as the protons shift back to their equilibrium state. The initial amplitude of the voltage induced in this loop by this relaxation electromagnetic field is directly proportional to the groundwater content. The groundwater flow is modelled by numerically solving Richards' 1D equation with time-variable boundary conditions. The upper (flux) boundary condition is computed from raw precipitations measured at the summit meteorological station, taking into account the presence of a snow layer and the effects of interception and evapotranspiration. The lower (pressure) boundary condition is derived from the water table level measured at the piezometer close to the SNMR station. Given a set of hydrologic parameters, one can compute the water content distributions at the time steps corresponding to SNMR data acquisition and use these water content distributions to compute the SNMR signals, Fig. 2. 4: Global sensitivity analysis In order to quantify the sensitivity of the SNMR signals to variations in the hydrological parameters, we used a tool called variance-based sensitivity analysis. The principle of variance-based sensitivity analysis is to consider a model's input parameters as random variables following given distributions. Then, a computational framework developed by Sobol (Sobol′ 2001) allows for the quantification of the impact of each model input parameter variance on the model output variance through sensitivity indices called Sobol indices. We were able to distinguish the most influential parameters from those that have a negligible impact on the SNMR signal variance.

Quantification of small molecule partitioning in a biomolecular condensate with 2D NMR spectroscopy

2025-05-28

Julie Maiboell Buhl , Sujata Mahapatra , Magnus Kjærgaard +1 more | bioRxiv (Cold Spring Harbor Laboratory)

Several intrinsically disordered proteins have been shown to undergo phase separation into a dense and dilute phase and this process is intimately linked with the regulation of cellular processes. It … Several intrinsically disordered proteins have been shown to undergo phase separation into a dense and dilute phase and this process is intimately linked with the regulation of cellular processes. It is therefore highly relevant to know how metabolites partition between these phases. We show here that the partitioning of components in a complex mixture can be robustly obtained from a single set of 2D NMR spectra recorded on the dilute and dense phases separately using a so-called "time zero extrapolated approach" known as HSQC 0 . The spectral separation power of 2D NMR spectroscopy circumvents the need for physical isolation or workup of the mixture components in the two samples. Using quantitative 1D 1 H NMR, it is validated that the HSQC 0 approach effectively removes all the undermining effects that plague quantification in common 2D NMR experiments, including differential attenuation due to relaxation in the two phases, pulse imperfections, partial decoupling, off-resonance effects, and incomplete coherence transfer in the case of scalar coupling variation. These results should be of widespread interest as partitioning into biomolecular condensates is crucial for the calibration of computational physicochemical models of phase separation and key to the further understanding of cellular biochemistry involving membraneless organelles.