Peter McDonald

Prof Peter McDonald


Professor of Physics
+44 (0)1483 686798
19 BB 03

Biography

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Publications

Monteilhet L, Korb JP, Mitchell J, McDonald PJ (2006) Observation of exchange of micropore water in cement pastes by two-dimensional T(2)-T(2) nuclear magnetic resonance relaxometry., Phys Rev E Stat Nonlin Soft Matter Phys 74 (6 Pt 1)
The first detailed analysis of the two-dimensional (2D) NMR T(2)-T(2) exchange experiment with a period of magnetization storage between the two T(2) relaxation encoding periods (T(2)-store-T(2)) is presented. It is shown that this experiment has certain advantages over the T(1)-T(2) variant for the quantization of chemical exchange. New T(2)-store-T(2) 2D 1H NMR spectra of the pore water within white cement paste are presented. Based on these spectra, the exchange rate of water between the two smallest porosity reservoirs is estimated for the first time. It is found to be of the order of 5 ms{-1}. Further, a careful estimate of the pore sizes of these reservoirs is made. They are found to be of the order of 1.4 nm and 10-30 nm , respectively. A discussion of the results is developed in terms of possible calcium silicate hydrate products. A water diffusion coefficient inferred from the exchange rate and the cement particle size is found to compare favorably with the results of molecular-dynamics simulations to be found in the literature.
Leone B, Halse MR, Strange JH, Lonergan AR, McDonald PJ, Smith E (1994) Ingress of water into zeolite 4A powder plugs, Magnetic Resonance Imaging 12 (2) pp. 247-248
One dimensional profiles of the concentration of water absorbed from vapour diffusing into compacted type 4A zeolite powder have been obtained by broadline NMR imaging. After an induction period of
Scrimgeour SN, Lloyd CH, Hunter G, Chudek JA, Lane DM, McDonald PJ (1998) Nuclear magnetic resonance imaging of fluoride in solid dental cements., JOURNAL OF DENTAL RESEARCH 77 pp. 785-785 AMER ASSOC DENTAL RESEARCH
McDonald PJ, Mitchell J, Mulheron M, Aptaker PS, Korb J-P, Monteilhet L (2007) Two-dimensional correlation relaxometry studies of cement pastes performed using a new one-sided NMR magnet, CEMENT AND CONCRETE RESEARCH 37 (3) pp. 303-309 PERGAMON-ELSEVIER SCIENCE LTD
MCDONALD PJ, VIJAYARAGHAVAN D, DEBENHAM PM, HORSEWILL AJ (1994) THE PRESSURE-DEPENDENCE OF MOLECULAR-DYNAMICS MEASURED BY NMR, PHYSICA B 202 (3-4) pp. 346-350 ELSEVIER SCIENCE BV
McDonald PJ, Akhmerov A, Backhouse LJ, Pitts S (2005) Magnetic resonance profiling of human skin in vivo using GARField magnets., J Pharm Sci 94 (8) pp. 1850-1860
It is shown that one-dimensional magnetic resonance imaging (MRI-profiling) of human forearm and side-of-hand skin in vivo is possible using GARField magnets. Strong profile contrast originating from differing molecular mobility is seen for stratum corneum and viable epidermis. The first in vivo spatially-resolved field-gradient measurements of water self-diffusivity, D, in the stratum corneum (2.0 x 10(-6) cm(2)/s) and viable epidermis (8.5 x 10(-6) cm(2)/s) are reported. Also reported are spatially resolved measurements of the (1)H spin-lattice relaxation time, T(1), the spin-spin relaxation time, T(2). It is further shown that the application of moisturizing agents to the skin noticeably affects the profiles. However, universal behavior is not seen as both signal increases and decreases are observed dependent on agent and volunteer.
Bhatt JS, McDonald PJ, Faux DA, Howlett NC, Churakov SV (2014) NMR relaxation parameters from molecular simulations of hydrated inorganic nanopores, International Journal of Quantum Chemistry 114 (18) pp. 1220-1228
Nuclear magnetic resonance (NMR) relaxometry is a powerful technique to characterize diffusive motion of fluids in nanoporous to microporous media. Molecular simulations can be used to predict NMR relaxation parameters using a dipolar spin-spin correlation function. In this article, molecular dynamics simulations of water diffusion in anomalous 11 Å tobermorite, consisting of three slit pores and one gel pore of width
Perry KL, McDonald PJ, Clough AS (1994) Case II diffusion in the PVC and acetone system., Magn Reson Imaging 12 (2) pp. 217-219
This paper describes how nuclear magnetic resonance (NMR) has been used to study case II diffusion of acetone into PVC. NMR is supported by Ion Beam Nuclear Reaction Analysis and Gravimetric Analysis. A series of experiments with different PVC exposure times to acetone vapour have shown the observable physical characteristics of case II diffusion. Experiments in the temperature range 20-50 degrees C have yielded the temperature dependence of the front velocity and the T2 values of the acetone and PVC components.
MCDONALD PJ, ATTARD JJ, TAYLOR DG (1987) A NEW APPROACH TO THE NMR IMAGING OF SOLIDS, JOURNAL OF MAGNETIC RESONANCE 72 (2) pp. 224-229 ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS
Wallin M, Glover PM, Hellgren AC, Keddie JL, McDonald PJ (2000) Depth profiles of polymer mobility during the film formation of a latex dispersion undergoing photoinitiated cross-linking, MACROMOLECULES 33 (22) pp. 8443-8452 AMER CHEMICAL SOC
Karakosta E, McDonald PJ (2007) An MRI analysis of the dissolution of a soluble drug incorporated within an insoluble polymer tablet, APPLIED MAGNETIC RESONANCE 32 (1-2) pp. 75-91 SPRINGER WIEN
CLOUGH S, MCDONALD PJ (1982) THE CORRELATION OF METHYL TUNNELLING AND THERMALLY ACTIVATED REORIENTATION .2., JOURNAL OF PHYSICS C-SOLID STATE PHYSICS 15 (29) pp. 1039-1042 IOP PUBLISHING LTD
Keddie JL, Ciampi E, McDonald PJ, Salamanca JM (1999) Magnetic resonance imaging of the film formation of waterborne coatings., ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 218 pp. U621-U621
BENSON TB, MCDONALD PJ (1993) MAGNETIZATION REWIND DURING A FINITE RF PULSE IN GRADIENT-ECHO MAGNETIC-RESONANCE-IMAGING, PHYSICA B 192 (3) pp. 269-273 ELSEVIER SCIENCE BV
McDonald PJ, O'Reilly EP (1989) Ultrasound speedometer, Physics Education 24 (4) pp. 237-239
Faux DA, McDonald PJ, Howlett NC, Bhatt JS, Churakov SV (2013) Nuclear magnetic resonance relaxometry of water in two and quasi-two dimensions, Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 87 (6)
Molecular dynamics (MD) and Monte Carlo (MC) methods are used to determine the spin-pair correlation function G*(t) for the diffusion of bulk water in three dimensions (3D) and pore water in two dimensions (2D) and quasi-two dimensions (Q2D). The correlation function is required for the determination of the nuclear magnetic resonance spin-lattice and spin-spin relaxation times T1 and T2. It is shown that the analytic form of the powder-average correlation function, introduced by Sholl for the diffusion of spins on a 3D lattice, is of general validity. An analytic expression for G*(t) for a uniform spin fluid is derived in 2D. An analytic expression for the long-time behavior of G*(t) is derived for spins diffusing on 3D, 2D, and Q2D lattices. An analytic correction term, which accounts for spin pairs outside the scope of the numerical simulations, is derived for 3D and 2D and shown to improve the accuracy of the simulations. The contributions to T1 due to translational and rotational motion obtained from the MD simulation of bulk water at 300 K are 7.4 s and 10±1 s, respectively, at 150 MHz, leading to an overall time of 4.3±0.4 s compared to the experimental value of 3.8 s. In Q2D systems, in which water is confined by alpha-quartz surfaces to thicknesses of 1-5 nm, T1 for both translational and rotational relaxation is reduced due to the orientation and adsorption of spins at the surfaces. A method of parametrizing the MC lattice-diffusion simulations in 3D, 2D, and Q2D systems is presented. MC results for G*(t) for 3D and 2D systems are found to be consistent with an analytic uniform fluid model for tâ040 ps. The value of T1 for translational diffusion obtained from the MC simulation of bulk water is found to be 4.8 s at 15 MHz. G*(t) obtained from MC simulations of Q2D systems, where water is confined by hard walls, is found to execute a distinct transition from 3D to 2D behavior. The T1 is found to be similar to the 3D bulk water result at all pore thicknesses. © 2013 American Physical Society.
ROBERTS SP, MCDONALD PJ, PRITCHARD T (1995) A BULK AND SPATIALLY-RESOLVED NMR RELAXATION STUDY OF SANDSTONE ROCK PLUGS, JOURNAL OF MAGNETIC RESONANCE SERIES A 116 (2) pp. 189-195 ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS
Ciampi E, Goerke U, McDonald PJ, Chambers JG, Newling B (2002) Spatially-resolved magnetic resonance study of the dissolution interface between soaps and water, JOURNAL OF PHYSICS D-APPLIED PHYSICS 35 (11) PII S0022-3727(02)33741-0 pp. 1271-1281 IOP PUBLISHING LTD
Backhouse L, Dias M, Gorce JP, Hadgraft J, McDonald PJ, Wiechers JW (2004) GARField magnetic resonance profiling of the ingress of model skin-care product ingredients into human skin in vitro., J Pharm Sci 93 (9) pp. 2274-2283
A preliminary study of the ingress of mineral oil, decanol, and glycerine into samples of human abdominal skin tissue in vitro made using magnetic resonance profiling with a GARField magnet is reported. Two layers, each circa 50 microm thick and attributed to stratum corneum and viable epidermis, are spatially resolved. Clear differences are observed in the magnetic resonance response of these layers arising from the application of the model skin-care product ingredients. In the case of decanol and glycerine, it is suggested that the profiles show evidence for the effects of moisturization, as distinct from hydration. In the case of glycerine, the effective ingress diffusion coefficient is calculated to be 1.3 +/- 0.5 x 10(-9) cm2s(-1).
Doughty PJ, Mcdonald PJ (2006) Hardware and Methods: Drying of Coatings and Other Applications with GARField, pp. 89-107
TOKARCZUK PF, MCDONALD PJ (1992) PROPERTIES AND DERIVATIVES OF THE SOLID-STATE IMAGING SEQUENCE ZIGZAG, JOURNAL OF MAGNETIC RESONANCE 99 (2) pp. 225-234 ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS
Zamani S, Kowalczyk RM, McDonald PJ (2014) The relative humidity dependence of the permeability of cement paste measured using GARField NMR profiling, Cement and Concrete Research 57 pp. 88-94 Elsevier
The relative humidity (RH) dependence of the water permeability of cement is calculated from the water concentration profile of a paste exposed to an RH gradient and the desorption isotherm. The profile is measured using GARField, standing for Gradient at Right Angles to Field, NMR. The isotherm is derived from other earlier NMR measurements. The Darcy equation gives the intrinsic permeability as 4.6 × 10 m. The apparent intrinsic permeability to water flow shows a broad "U" shape dependence on RH, with a minimum of 7 × 10 m at RH 55%. The "U" shape is attributed to the fact that the transport mechanism involves a coupling of liquid and vapour modes. The data is further analysed in terms of a model of coupled liquid and vapour diffusion and Darcy flow due to Baroghel-Bouny et al. (Cem. Concr. Res. 2011 41 828) from which the relative liquid water and vapour permeabilities are calculated. They are strongly RH dependent. The former increases with increasing RH; the latter decreases. © 2013 Elsevier Ltd.
Brougham DF, Horsewill AJ, Ikram A, Ibberson RM, McDonald PJ, PinterKrainer M (1996) The correlation between hydrogen bond tunneling dynamics and the structure of benzoic acid dimers, JOURNAL OF CHEMICAL PHYSICS 105 (3) pp. 979-982 AMER INST PHYSICS
Muller ACA, Scrivener KL, Skibsted J, Gajewicz AM, McDonald PJ (2015) Influence of silica fume on the microstructure of cement pastes: New insights from <sup>1</sup>H NMR relaxometry, Cement and Concrete Research 74 pp. 116-125
© 2015 Elsevier Ltd. All rights reserved.1H NMR has been used to characterise white Portland cement paste incorporating 10 wt.% of silica fume. Samples were measured sealed throughout the hydration without sample drying. Paste compositions and C-S-H characteristics are calculated based on 1H NMR signal intensities and relaxation analysis. The results are compared with a similar study of plain white cement paste. While the presence of silica fume has little influence on C-S-H densities, the chemical composition is impacted. After 28 days of sealed hydration, the Ca/(Si + Al) ratio of the C-S-H is 1.33 and the H2O/(Si + Al) ratio is 1.10 when 10% of silica fume is added to the white cement. A densification of the C-S-H with time is observed. There are no major changes in capillary, C-S-H gel and interlayer pore sizes for the paste containing silica fume compared to the plain white cement paste. However, the gel/interlayer water ratio increases in the silica fume blend.
MCDONALD PJ, LONERGAN AR (1992) 2-DIMENSIONAL FOURIER-TRANSFORM NMR IMAGING OF SOLIDS USING MULTIPLE PULSE LINE NARROWING, PHYSICA B 176 (3) pp. 173-179 ELSEVIER SCIENCE BV
MCDONALD PJ, PINTERKRAINER M (1995) HIGH-PRESSURE NMR-STUDY OF METHYL-GROUP TUNNELING IN DIMETHYL SULFIDE, MOLECULAR PHYSICS 84 (5) pp. 1021-1031 TAYLOR & FRANCIS LTD LONDON
McDonald P, Strange J (1998) Magnetic resonance and porous materials, PHYSICS WORLD 11 (7) pp. 29-34 IOP PUBLISHING LTD
Zalzale M, McDonald PJ, Scrivener KL (2013) A 3D lattice Boltzmann effective media study: Understanding the role of C-S-H and water saturation on the permeability of cement paste, Modelling and Simulation in Materials Science and Engineering 21 (8)
A 3D lattice Boltzmann model is developed and used to calculate the water and gas permeabilities of model cement pastes at different degrees of water saturation. In addition to permeable micron-sized capillary pores and impermeable solid inclusions, the lattice Boltzmann model comprises weakly-permeable nano-porous calcium silicate hydrate (C-S-H). The multi-scale problem is addressed by using an effective media approach based on the idea of partial bounce-back. The model cement paste microstructures are generated with the platform ¼ic. The critical parameters, C-S-H density and capillary porosity, are taken from 1H nuclear magnetic resonance relaxation analysis. The distribution of water and air is defined according to the Kelvin-Laplace law. It is found that when the capillary porosity is completely saturated with a fluid (either water or gas), the calculated intrinsic permeability is in good agreement with measurements of gas permeability on dried samples (10-17-10-16 m2). However, as the water saturation is reduced, the calculated apparent water permeability decreases and spans the full range of experimentally measured values (10 -16-10-22 m2). It is concluded that the degree of capillary water saturation is the major cause for variation in experimental permeability measurements. It is further concluded that the role of the weakly-permeable C-S-H, omitted in earlier modelling studies, is critical for determining the permeability at low capillary saturation. © 2013 IOP Publishing Ltd.
Glover PM, Aptaker PS, Bowler JR, Ciampi E, McDonald PJ (1999) A novel high-gradient permanent magnet for the profiling of planar films and coatings., J Magn Reson 139 (1) pp. 90-97
The design and construction of a low-cost, permanent magnet is described. The magnet is intended for applications which require a large static gradient, such as those for which stray field imaging or fringe field diffusometry are conventionally employed. The magnet has been designed using the scalar potential method. Particular features of the magnet include a field profile such that ||B || is constant in the horizontal plane and such that B is horizontal at the midpoint between the poles. There is a vertical, and therefore orthogonal, strong gradient, G, in ||B ||. The ratio G/ ||B || is constant within a large volume and so allows measurements at a range of gradient strengths. It is this ratio which governs the shape of the pole-pieces. The constructed magnet has a typical operating field of 0.8 T, gives a gradient of 20 Tm-1, and has a useable interpole access of 20 mm. Field plot data show values consistent with the theory. In particular ||B || has a curvature of less than +/-5 microm over a 5 x 5 mm area at the target field. The magnet is most suitable for the one-dimensional profiling of thin planar samples. As an example of the magnet's use, a profile of a sandwich structure made of several polymer layers is shown. In addition, a set of one-dimensional profiles of an alkyd coating, recorded during solvent loss and cross-linking, is presented. This example demonstrates quantitative T2 measurements at a resolution of 6.5 microm across a 70-microm-thick film.
McDonald PJ, O'Reilly EP (1989) Vibrating-bar depth gauge, Physics Education 24 (4) pp. 239-240
Benson TB, McDonald PJ (1995) Developments in STRAFI for the quantitative relaxation analysis of solvent inhibition into polymers, BULLETIN OF MAGNETIC RESONANCE, VOL 17, NOS 1-4, DECEMBER 1995 pp. 172-173 INT SOC MAGNETIC RESONANCE
Holl Y, Keddie JL, McDonald PJ, Winnik WA (2001) Drying modes of polymer colloids, ACS Symposium Series 790 pp. 2-26
This chapter reviews the complex step of drying in the latex film formation process. Drying modes have a profound effect on drying rates and on the final properties of films, primarily through their influence on film morphology and the distribution of water-soluble species. Three distinct drying modes (acting separately, successively or together) can be defined, namely homogeneous drying (in which the water concentration remains uniform in the sample throughout the drying process), drying normal to the surface (where a dry layer of increasing thickness develops from the air surface of the latex coating); and lateral drying (where dry areas increase in size in a direction parallel to the substrate). Details are given on the current knowledge and understanding of these drying modes. The last section of the chapter considers the main parameters controlling the drying modes, i.e. thickness and geometric effects, the structure and rheology of the dispersion, particle viscoelasticity, and the overall rate of water loss.
McDonald PJ, Godward J, Sackin R, Sear RP (2001) Surface flux limited diffusion of solvent into polymer, MACROMOLECULES 34 (4) pp. 1048-1057 AMER CHEMICAL SOC
McDonald PJ, Lane DM (1999) Magnetic resonance relaxation and imaging, POLYMER SURFACES AND INTERFACES III pp. 237-267 JOHN WILEY & SONS INC
CLOUGH S, MCDONALD PJ, ZELAYA FO (1984) THE TRANSITION FROM FREE QUANTUM TUNNELLING TO THERMALLY DRIVEN MOTION OF METHYL-GROUPS, JOURNAL OF PHYSICS C-SOLID STATE PHYSICS 17 (25) pp. 4413-4420 IOP PUBLISHING LTD
Mallegol J, Bennett G, McDonald PJ, Keddie JL, Dupont O (2006) Skin development during the film formation of waterborne acrylic pressure-sensitive adhesives containing tackifying resin, JOURNAL OF ADHESION 82 (3) pp. 217-238 TAYLOR & FRANCIS LTD
Zalzale M, McDonald PJ (2012) Lattice Boltzmann simulations of the permeability and capillary adsorption of cement model microstructures, Cement and Concrete Research 42 (12) pp. 1601-1610
The lattice Boltzmann method is used to investigate the permeability of microstructures of cement pastes generated using the numerical models CEMHYD3D (Bentz, 1997) and ¼IC (Bishnoi and Scrivener, 2009). Results are reported as a function of paste water-to-cement ratio and degree of hydration. The permeability decreases with increasing hydration and decreasing water-to-cement ratio in agreement with experiment. However the permeability is larger than the experimental data recorded using beam bending methods (Vichit-Vadakan and Scherer, 2002). Notwithstanding, the lattice Boltzmann results compare favourably with alternate numerical methods of permeability calculation for cement model microstructures. In addition, we show early results for the liquid/vapour capillary adsorption and desorption isotherms in the same model ¼IC structures. The broad features of the experimental capillary porosity isotherm are reproduced, although further work is required to adequately parameterise the model. © 2012 Elsevier Ltd.
Hughes PD, McDonald PJ, Rhodes NP, Rockliffe JW, Smith EG, Wills J (1996) A Stray Field Magnetic Resonance Imaging Study of the Drying of Sodium Silicate Films., J Colloid Interface Sci 177 (1) pp. 208-213
Stray field magnetic resonance imaging (STRAFI) is shown to be highly suited to the study of drying processes in thin films. Sodium silicate films have been chosen as a model system exhibiting many of the properties of film drying in general. Films have been dried, as a function of temperature in the range 22 to 62 degrees C, down to water contents of order 28% by weight, at which stage the film is glassy. The experimental results have been quantitatively analyzed by treating the drying film as a colloidal solution. The results suggest that the localized hydrogen spin-spin relaxation time, and hence the mobility of the water in the films is independent of the drying regime and depends primarily on the local water concentration.
MCDONALD PJ, HORSEWILL AJ, DUNSTAN DJ, HALL N (1989) THE PRESSURE-DEPENDENCE OF METHYL TUNNELLING IN MDBP FROM FIELD-CYCLING NMR-SPECTROSCOPY, JOURNAL OF PHYSICS-CONDENSED MATTER 1 (13) pp. 2441-2444 IOP PUBLISHING LTD
Glover PM, McDonald PJ, Newling B (1997) Stray-field imaging of planar films using a novel surface coil, JOURNAL OF MAGNETIC RESONANCE 126 (2) pp. 207-212 ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS
MCDONALD PJ, TOKARCZUK PF (1989) AN NMR MULTIPLE PULSE SEQUENCE FOR THE IMAGING OF SOLIDS USING SINUSOIDALLY DRIVEN MAGNETIC-FIELD GRADIENTS, JOURNAL OF PHYSICS E-SCIENTIFIC INSTRUMENTS 22 (11) pp. 948-951 IOP PUBLISHING LTD
McDonald PJ (1997) Stray field magnetic resonance imaging, PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 30 pp. 69-99 PERGAMON-ELSEVIER SCIENCE LTD
HORSEWILL AJ, MCDONALD PJ, VIJAYARAGHAVAN D (1994) HYDROGEN-BOND DYNAMICS IN BENZOIC-ACID DIMERS AS A FUNCTION OF HYDROSTATIC-PRESSURE MEASURED BY NUCLEAR-MAGNETIC-RESONANCE, JOURNAL OF CHEMICAL PHYSICS 100 (3) pp. 1889-1894 AMER INST PHYSICS
HEIDEMANN A, CLOUGH S, MCDONALD PJ, HORSEWILL AJ, NEUMAIER K (1985) TUNNELING MOTIONS OF METHYL-GROUPS IN MANGANESE ACETATE TETRAHYDRATE, ZEITSCHRIFT FUR PHYSIK B-CONDENSED MATTER 58 (2) pp. 141-148 SPRINGER
Ibberson RM, McDonald PJ, PinterKrainer M (1997) The crystal structure determination of dimethylsulphide by high-resolution neutron powder diffraction, JOURNAL OF MOLECULAR STRUCTURE 415 (3) pp. 259-266 ELSEVIER SCIENCE BV
McDonald PJ, Korb JP, Mitchell J, Monteilhet L (2005) Surface relaxation and chemical exchange in hydrating cement pastes: a two-dimensional NMR relaxation study., Phys Rev E Stat Nonlin Soft Matter Phys 72 (1 Pt 1)
We report the first nuclear magnetic resonance (NMR) two-dimensional correlation T(1) - T(2) and T(2) - T(2) measurements of hydrating cement pastes. A small but distinct cross peak in the two-dimensional relaxation spectrum provides the first direct evidence of chemical exchange of water between gel and capillary pores occurring over the first 14 days of hydration. A correlation of features along the line T(1) = 4T(2) provides strong supportive evidence for the surface diffusion model of (1)H nuclear spin relaxation in cements and for a multimodal discrete pore size distribution. Differences in detail of the results are reported for white cement paste and white cement paste with added silica fume. Both the method and the theory presented can be applied more widely to other high surface area materials with other reactive surface areas.
Hart TD, Chamberlain AHL, Lynch JM, Newling B, McDonald PJ (1999) A stray field magnetic resonance study of water diffusion in bacterial exopolysaccharides, ENZYME AND MICROBIAL TECHNOLOGY 24 (5-6) pp. 339-347 ELSEVIER SCIENCE INC
Rodriguez R, Alarcon CDLH, Ekanayake P, McDonald PJ, Keddie JL, Barandiaran MJ, Asua JM (2008) Correlation of Silicone Incorporation into Hybrid Acrylic Coatings with the Resulting Hydrophobic and Thermal Properties, MACROMOLECULES 41 (22) pp. 8537-8546 AMER CHEMICAL SOC
Fischer N, Haerdtl R, McDonald PJ (2015) Is colour change a good measure of a water penetration front?, MAGAZINE OF CONCRETE RESEARCH 67 (19) pp. 1048-1053 ICE PUBLISHING
Gajewicz AM, Gartner E, Kang K, McDonald RI, Yerrnakou V (2016) A H-1 NMR relaxometry investigation of gel-pore drying shrinkage in cement pastes, CEMENT AND CONCRETE RESEARCH 86 pp. 12-19 PERGAMON-ELSEVIER SCIENCE LTD
Rodin VV, McDonald PJ, Zamani Z (2013) A nuclear magnetic resonance pulsed field gradient study of self-diffusion of water in hydrated cement pastes, Diffusion Fundamentals 18 (3) pp. 1-7 Diffusion-Fundamentals
The results of one- and two-dimensional 1H nuclear magnetic resonance (NMR) pulsed
field gradient (PFG) diffusometry studies of water in white cement paste with a water-to-cement ratio 0.4 and aged from 1 day to 1 year are reported. The study shows that the NMR PFG method is primarily sensitive to the capillary porosity. Data is fit on the basis of a lognormal pore size distribution with pore size dependent relaxation times. The volume mean capillary pore size is 4.2 ¼m in mature paste, similar to 1 week suggesting that hydrates and gel porosity do not form in the capillary porosity once the latter has been substantially created. No evidence is found of capillary pore anisotropy in cement paste.
Keddie JL, Gorce JP, Mallegol J, Wallin M, Barry AM, Ciampi E, Motiejauskaite A, Glover PM, McDonald PJ, Weissenborn PK (2001) MR profiling of film formation and crosslinking in waterborne alkyd emulsions and emulsion paints., ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 222 pp. U378-U378 AMER CHEMICAL SOC
Attard JJ, McDonald PJ, Roberts SP, Taylor T (1994) Solid state NMR imaging of irreducible water in reservoir cores for spatially resolved pore surface relaxation estimation, Magnetic Resonance Imaging 12 (2) pp. 355-359
The use of solid state NMR imaging in reservoir core applications has long been proposed. This paper describes the use of a simple, robust technique in the first such application. One- and two-dimensional images of the irreducible brine in a sandstone and carbonate reservoir core are demonstrated. The applicability of solid state NMR imaging to pore surface relaxation estimation is discussed. © 1994.
Sackin R, Ciampi E, Godward J, Keddie JL, McDonald PJ (2001) Fickian ingress of binary solvent mixtures into glassy polymer, MACROMOLECULES 34 (4) pp. 890-895 AMER CHEMICAL SOC
Mitchell J, Bluemler P, McDonald PJ (2006) Spatially resolved nuclear magnetic resonance studies of planar samples, PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 48 (4) pp. 161-181 PERGAMON-ELSEVIER SCIENCE LTD
McDonald PJ, Stapf S, Fantazzini P, Bortolotti V, Mitchell J (2013) Proceedings of the 11th International Bologna Conference on Magnetic Resonance in Porous Media (MRPM11), Microporous and Mesoporous Materials
Goerke U, Chamberlain AH, Crilly EA, McDonald PJ (2000) Model for water transport into powdered xanthan combining gel swelling and vapor diffusion., Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 62 (4 Pt B) pp. 5353-5359
Water ingress into xanthan powder compressed to various packing densities has been studied using nuclear magnetic resonance stray field imaging (STRAFI). A foot is observed ahead of the main water ingress front which is attributed to vapor transport around the particles. The main development of the reported work is an analytical model which describes the coupling of vapor transport through the pore space and liquid transport through the progressively swelling gel which gradually occludes the vapor path. Good agreement between theory and experiment is found over a wide range of packing densities with the model requiring only one adjustable parameter, the water diffusivity in the gel measured in a constant polymer mass reference frame. It is suggested that the results are of considerable relevance to situations where the polymer is produced at low concentration by bacteria such as in the rhizosphere and aerial bio films.
McDonald PJ, Gajewicz AM, Morrell R (2016) The characterisation of cement based materials using T2 1H nuclear magnetic resonance relaxation analysis, pp. 1-165 NPL Management Ltd
This Guide is an introduction to the basic concepts of using 1H nuclear magnetic resonance (NMR) relaxometry to determine the state of water in cement, and hence the degree of cure of the cement and the cement microstructure, in particular the porosity. The Guide provides information on calibrating the equipment, the NMR responses that can typically be found from cement and on how to quantify the information obtained. Recommendations are made for the specification of suitable equipment, the set-up procedures required, and the experiments to be performed. Detailed results of an international round robin are included to demonstrate the usability, repeatability and accuracy of the method. The preparation of suitable non-cementitious reference materials is discussed.
Hughes PDM, McDonald PJ, Smith EG (1996) Long-range water transport and self-diffusion in zeolite 4A powder beds, JOURNAL OF MAGNETIC RESONANCE SERIES A 121 (2) pp. 147-153 ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS
Bennett G, Gorce JP, Keddie JL, McDonald PJ, Berglind H (2003) Magnetic resonance profiling studies of the drying of film-forming aqueous dispersions and glue layers., Magn Reson Imaging 21 (3-4) pp. 235-241
We report magnetic resonance profiling experiments to monitor (i) the drying of alkyd emulsion layers, (ii) the cure of wood glue layers and (iii) water transport through glue lines. The alkyd drying is a two stage process. We report new results which support previous evidence that the alkyd drops do not coalesce until the water fraction is below circa 0.02. The profiles recorded from glue layers suggest that MR is a sensitive probe of the curing process and barrier properties of the glue. The measurements were made using GARField (stray field, STRAFI like) magnetic resonance profiling and an improved GARField magnet design characterized by two values of the gradient-to-field strength ratio at two locations offering the same field strength is also reported.
Chowdhury A, Gillies A, McDonald PJ, Mulheron M (2001) Vapour phase application of hydrophobic coatings to cement-based materials, MAGAZINE OF CONCRETE RESEARCH 53 (5) pp. 347-352 THOMAS TELFORD SERVICES LTD
Bohris AJ, Newling B, McDonald PJ, Raoof A, Tran NL (1998) A broad-line nuclear magnetic resonance study of water absorption and transport in fibrous cement roofing tiles, JOURNAL OF MATERIALS SCIENCE 33 (4) pp. 859-867 KLUWER ACADEMIC PUBL
Mallegol J, Barry AM, Ciampi E, Glover PM, McDonald PJ, Keddie JL, Wallin M, Motiejauskaite A, Weissenborn PK (2002) Influence of drier combination on through-drying in waterborne alkyd emulsion coatings observed with magnetic resonance profiling, JOURNAL OF COATINGS TECHNOLOGY 74 (933) pp. 113-124 FEDERATION SOC COATING TECH
Rodin V, Valori A, McDonald PJ (2011) A 1H double-quantum-filtered NMR study of water in
cement pastes,
New Journal of Physics 13 035017 pp. 1-13 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft
The results of a 1H double-quantum-filtered (DQF) nuclear magnetic
resonance (NMR) study of water in cement pastes are reported. It is shown
that the DQF signal increases with curing time and in sympathy with the loss
of mobile single-quantum signal, suggesting strongly that a signal from 1H
in chemically combined and strongly confined water is selectively observed.
The DQF signal in white cement comprises at least two components: the first
is assigned to portlandite (Ca(OH)2); the second is assigned to water in the
planar, nanometre-wide, calcium?silicate?hydrate (C?S?H) gel pores. The pore
water signal is significantly broader than that expected for bound water. The
width is interpreted in terms of the water undergoing a two-dimensional walk
in the vicinity of Fe3+ impurities. A simple model is presented and found to be
consistent with experiment and the known Fe3+ concentration. In grey cements,
a third component is identified and associated with Fe-rich phases. The analysis
places a lower bound on the lateral extent of planar C?S?H pores. The change
in DQF signal components upon drying a sample mirrors the loss of the singlequantum
components observed in a parallel study.
Bohris AJ, Goerke U, McDonald PJ, Mulheron M, Newling B, Le Page B (1998) A broad line NMR and MRI study of water and water transport in Portland cement pastes., Magn Reson Imaging 16 (5-6) pp. 455-461
The results of a magnetic resonance spin-spin relaxation analysis and broad-line magnetic resonance imaging (MRI) (gradient-echo and stray-field imaging) study of water and water transport in Portland cement pastes are presented. The effect of varying the cure conditions and the water to cement (w/c) ratio of the sample of mix are discussed. The water sorptivity and the concentration dependence of the hydraulic diffusion coefficient are calculated for samples prepared with a 0.5 w/c ratio and, therefore, an open pore structure. In the case of 0.3 w/c ratio samples, little water transport is observed, and a closed pore structure is inferred.
Gorce JP, Bovey D, McDonald PJ, Palasz P, Taylor D, Keddie JL (2002) Vertical water distribution during the drying of polymer films cast from aqueous emulsions., Eur Phys J E Soft Matter 8 (4) pp. 421-429
We present a systematic study of the vertical uniformity of water distribution during the drying of waterborne colloidal films, testing the predictions of a Peclet number Pe defined for this system. Pe indicates the relative contributions of water evaporation and Brownian diffusion in determining the concentration profile in the vertical direction ( i.e. normal to the substrate). When Pe 1, a gradient in the water concentration develops, with less water near the interface with air. The water profiles reveal that the alkyd particles do not coalesce immediately upon contact in close-packing. At later times, a concentrated surface layer develops, but particles are not coalesced in this layer to form a continuous "skin", but rather the structure is likely to be that of a biliquid foam.
McDonald PJ, Gajewicz AM, Morrell R (2016) 1H NMR characterisation of pore water in cement materials, Proceedings of the 36th Cement and Concrete Science Conference
This paper presents summary results of a Round Robin Trial to examine the reproducibility and robustness of
1H NMR relaxation analysis of water in cements. The results have elsewhere been used to evidence a good
practice guide for the characterization of cement using 1H NMR relaxation analysis. A summary of the good
practice is presented
Cox J, McDonald PJ, Gardiner BA (2010) A study of water exchange in wood by means of 2D NMR relaxation correlation and exchange, HOLZFORSCHUNG 64 (2) pp. 259-266 WALTER DE GRUYTER & CO
Gorce JP, Milestone NB, McDonald PJ (2006) Probing the water phases and microstructure in a model cement blend matrix used for the encapsulation of intermediate level nuclear wastes, Materials Research Society Symposium Proceedings 932 pp. 767-774
The changes in microstructure and content of water phases during hydration of a 3:1 BFS:OPC blend are investigated by Mercury Intrusion Porosimetry (MIP), freeze-drying, Thermal Gravimetric Analysis (TGA) and 1H Nuclear Magnetic Resonance (NMR) relaxometry. MIP indicates that during the blend hydration, a reduction in the population of capillary pores (larger than about 100 nm) occurs while the population of gel pores (smaller than few tens of nanometres) increases. Between 3 and 90 days, the porosity estimated by MIP decreases from about 36% down to 18% while the median pore size decreases from about 140 nm down to 6 nm. 1HNMR relaxometry shows that after 1 day of hydration, nearly 70% of the evaporable water is held in capillary pores while about 30% is present in gel pores. After two weeks, most of the evaporable water (90%) is found in pores smaller than few tens of nanometres. : The amount of evaporable water detected by freeze drying decreases from less than 20 wt.% after one week of hydration down to about 16.3 wt.% after 90 days while the amount of chemical ly bound water related to the degree of advancement of the cement hydration and detected by TGA increases from 8 wt.% to 10.3 wt.%. During hydration the BFS:OPC blend matrix evolves from an open microporous network to one of a poorly connected network of water rich nanopores with increasing amounts of chemically bound water. © 2006 Materials Research Society.
Benson TB, McDonald PJ (1995) The application of spin echoes to stray-field imaging, JOURNAL OF MAGNETIC RESONANCE SERIES B 109 (3) pp. 314-317 ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS
Godward J, Ciampi E, Cifelli M, McDonald PJ (2002) Multidimensional imaging using combined stray field and pulsed gradients., J Magn Reson 155 (1) pp. 92-99
The paper describes an advance in stray field imaging (STRAFI) whereby images of planar samples can be obtained in the stray field of a superconducting magnet without the need for sample rotation. This is achieved by using the static stray magnetic field gradient in combination with pulsed orthogonal gradients. Results of both two- and three-dimensional implementations of the experiment are presented and discussed. An extension to diffusion-weighted imaging is introduced. The technique is expected to prove particularly useful in experiments where high resolution is required in only one direction while lower resolution is acceptable in the orthogonal directions, such as in studies of the drying and curing of paints and varnishes. Arising from the work, a new method for accurately calibrating the radiofrequency pulse width in stray field is found.
Cifelli M, McDonald PJ, Veracini CA (2004) Translational self diffusion in 4-n-octyloxy-4 '-cyanobiphenyl (8OCB) exploited with a static field gradient H-1 NMR diffusometry approach, PHYSICAL CHEMISTRY CHEMICAL PHYSICS 6 (19) pp. 4701-4706 ROYAL SOC CHEMISTRY
Korb J-P, McDonald PJ, Monteilhet L, Kalinichev AG, Kirkpatrick RJ (2007) Comparison of proton field-cycling relaxometry and molecular dynamics simulations for proton-water surface dynamics in cement-based materials, CEMENT AND CONCRETE RESEARCH 37 (3) pp. 348-350 PERGAMON-ELSEVIER SCIENCE LTD
McDonald PJ, Ciampi E, Keddie JL, Heidenreich M, Kimmich R (1999) Magnetic-resonance determination of the spatial dependence of the droplet size distribution in the cream layer of oil-in-water emulsions: Evidence for the effects of depletion flocculation, Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics 59 (1) pp. 874-884
It is shown that a combination of pulsed-field-gradient spin-echo (PGSE) nuclear-magnetic-resonance (NMR) restricted diffusion analysis and NMR imaging may be used to measure the spatial dependence of the droplet size distribution in the cream layer of turbid oil-in-water emulsions. 1H-13C cyclic J cross-polarization PGSE is introduced as a technique for this purpose in cases where selective observation of the oil component (or other carbohydrate constituent) is required. With this method, 13C nuclei are chemical shift selectively excited by cross-polarization from coupled 1H partners. An optimum detection sensitivity is ensured by transferring the polarization back to the coupled protons with which the combined imaging and diffusion experiment is then carried out. The spatial dependence of the oil droplet size distribution was measured for a series of emulsions containing various fractions of gum xanthan thickener dissolved in the water. The experimental results are compared with a recent model of the creaming process due to Pinfield, Dickinson, and Povey [J. Colloid Interface Sci. 166, 363 (1994)]. When no gum xanthan is present, the experimental results are in good agreement with the model. However, the model fails to describe the droplet distribution for emulsions with a gum xanthan concentration of the order of 0.1 wt%. The discrepancy is discussed in terms of depletion flocculation and depletion stabilization. ©1999 The American Physical Society.
MCDONALD PJ, TORR BP (1986) IMPROVEMENT OF SIGNAL TO NOISE IN AUTOMATED NUCLEAR-MAGNETIC-RESONANCE EXPERIMENTS, JOURNAL OF PHYSICS E-SCIENTIFIC INSTRUMENTS 19 (7) pp. 563-563 IOP PUBLISHING LTD
Zalzale M, Ramaioli M, Scrivener KL, McDonald PJ (2016) Gray free-energy multiphase lattice Boltzmann model with effective transport and wetting properties, Physical Review E: Statistical, Nonlinear, and Soft Matter Physics 94 (5)
The paper shows that it is possible to combine the free energy lattice Boltzmann approach to multi-phase modelling of fluids involving both liquid and vapour with the partial bounce back lattice
Boltzmann approach to modelling effective media. Effective media models are designed to mimic
the properties of porous materials with porosity much finer than the scale of the simulation lattice.
In the partial bounce back approach, an effective media parameter or bounce back fraction controls fluid transport. In the combined model, a wetting potential is additionally introduced that controls the wetting properties of the fluid with respect to interfaces between free space (white nodes), effective media (grey nodes) and solids (black nodes). The use of the wetting potential combined with the bounce back parameter gives the model the ability to simulate transport and sorption of
a wide range of fluid / material systems. Results for phase separation, permeability, contact angle
and wicking in grey media are shown. Sorption is explored in small sections of model multi-scale
porous systems to demonstrate two-step desorption, sorption hysteresis and the ink-bottle effect.
Dias M, Hadgraft J, Glover PM, McDonald PJ (2003) Stray field magnetic resonance imaging: a preliminary study of skin hydration, JOURNAL OF PHYSICS D-APPLIED PHYSICS 36 (4) PII S0022-3727(03)37441-8 pp. 364-368 IOP PUBLISHING LTD
Smith EG, Rockliffe JW, McDonald PJ, Lonergan A, Halse MR, Leone B, Strange JH (1994) NMR studies of molecular mobility and diffusion in porous systems, Magnetic Resonance Imaging 12 (2) pp. 231-234
The uptake, partitioning, and release of ingredients such as water, oil, surfactant, and ions are important factors to understand and control in the design and manufacture of detergent and personal products. Although conventional pulse NMR (PNMR) spectroscopy continues to be used to analyse bulk molecular mobility and phase composition, more recently MR imaging techniques have created unique opportunities for gaining spatial information about these processes in ways that are noninvasive and potentially quantitative. This paper describes the evaluation of MRI and associated PNMR techniques to study transport in three relevant cases: ion diffusion (e.g., fluoride) in concentrated dispersions, oil transport through powders, and water ingress into porous powders (zeolite). Results are presented to illustrate the potential of multiple pulse and gradient echo MRI methods for dealing with the short T2 scenarios that represent a common problem in quantitative imaging of water in solid-containing composites involving, for instance, zeolite, or silica. Pore-size characterisation results are also presented. © 1994.
Muller ACA, Mitchell J, McDonald PJ (2016) Proton nuclear magnetic resonance relaxometry, 7 pp. 287-349 CRC Press
McDonald PJ, Lonergan AR (1992) Two-dimensional fourier transform NMR imaging of solids using multiple pulse line narrowing, Physica B: Physics of Condensed Matter 176 (3) pp. 173-179
A method of two-dimensional Fourier transform magnetic resonance imaging using a multiple pulse line narrowing sequence combined with amplitude modulated magnetic field gradients is described. The new method is compared experimentally with other techniques of this kind. © 1992.
Hopkinson I, Jones RAL, McDonald PJ, Newling B, Lecat A, Livings S (2001) Water ingress into starch and sucrose : starch systems, POLYMER 42 (11) pp. 4947-4956 ELSEVIER SCI LTD
CLOUGH S, MCDONALD PJ (1983) THE NUMBER OF SPIN SYMMETRY SPECIES OF TUNNELLING MOLECULAR GROUPS, JOURNAL OF PHYSICS C-SOLID STATE PHYSICS 16 (30) pp. 5753-5764 IOP PUBLISHING LTD
Valori A, Rodin V, McDonald PJ (2010) On the interpretation of H-1 2-dimensional NMR relaxation exchange spectra in cements: Is there exchange between pores with two characteristic sizes or Fe3+ concentrations?, CEMENT AND CONCRETE RESEARCH 40 (9) pp. 1375-1377 PERGAMON-ELSEVIER SCIENCE LTD
Hunter G, Lane DM, Scrimgeour SN, McDonald PJ, Lloyd CH (2003) Measurement of the diffusion of liquids into dental restorative resins by stray-field nuclear magnetic resonance imaging (STRAFI), DENTAL MATERIALS 19 (7) pp. 632-638 ELSEVIER SCI LTD
MCDONALD PJ (1988) A NUCLEAR MAGNETIC-RESONANCE FIELD CYCLING INVESTIGATION OF CHROMIUM AND SILICON DOPED GALLIUM-ARSENIDE, SOLID STATE COMMUNICATIONS 68 (1) pp. 163-166 PERGAMON-ELSEVIER SCIENCE LTD
Mallegol J, Gorce JP, Dupont O, Jeynes C, McDonald PJ, Keddie JL (2002) Origins and effects of a surfactant excess near the surface of waterborne acrylic pressure-sensitive adhesives, LANGMUIR 18 (11) pp. 4478-4487 AMER CHEMICAL SOC
Boguszynska J, Brown MCA, McDonald PJ, Mitchell J, Mulheron M, Tritt-Goc J, Verganelakis DA (2005) Magnetic resonance studies of cement based materials in inhomogeneous magnetic fields, CEMENT AND CONCRETE RESEARCH 35 (10) pp. 2033-2040 PERGAMON-ELSEVIER SCIENCE LTD
HUGHES PDM, MCDONALD PJ, HALSE MR, LEONE B, SMITH EG (1995) WATER DIFFUSION IN ZEOLITE-4-A BEDS MEASURED BY BROAD-LINE MAGNETIC-RESONANCE-IMAGING, PHYSICAL REVIEW B 51 (17) pp. 11332-11338 AMERICAN PHYSICAL SOC
McDonald PJ (1996) The application of broad line MRI to the study of porous media., Magn Reson Imaging 14 (7-8) pp. 807-810
Faux DA, Cachia SH, McDonald PJ, Bhatt JS, Howlett NC, Churakov SV (2015) Model for the interpretation of nuclear magnetic resonance relaxometry of hydrated porous silicate materials., Phys Rev E Stat Nonlin Soft Matter Phys 91 (3)
Nuclear magnetic resonance (NMR) relaxation experimentation is an effective technique for probing the dynamics of proton spins in porous media, but interpretation requires the application of appropriate spin-diffusion models. Molecular dynamics (MD) simulations of porous silicate-based systems containing a quasi-two-dimensional water-filled pore are presented. The MD simulations suggest that the residency time of the water on the pore surface is in the range 0.03-12 ns, typically 2-5 orders of magnitude less than values determined from fits to experimental NMR measurements using the established surface-layer (SL) diffusion models of Korb and co-workers [Phys. Rev. E 56, 1934 (1997)]. Instead, MD identifies four distinct water layers in a tobermorite-based pore containing surface Ca2+ ions. Three highly structured water layers exist within 1 nm of the surface and the central region of the pore contains a homogeneous region of bulklike water. These regions are referred to as layer 1 and 2 (L1, L2), transition layer (TL), and bulk (B), respectively. Guided by the MD simulations, a two-layer (2L) spin-diffusion NMR relaxation model is proposed comprising two two-dimensional layers of slow- and fast-moving water associated with L2 and layers TL+B, respectively. The 2L model provides an improved fit to NMR relaxation times obtained from cementitious material compared to the SL model, yields diffusion correlation times in the range 18-75 ns and 28-40 ps in good agreement with MD, and resolves the surface residency time discrepancy. The 2L model, coupled with NMR relaxation experimentation, provides a simple yet powerful method of characterizing the dynamical properties of proton-bearing porous silicate-based systems such as porous glasses, cementitious materials, and oil-bearing rocks.
MCDONALD PJ, PERRY KL, ROBERTS SP (1993) A REPETITIVE PULSE VARIANT OF BROADLINE GRADIENT-ECHO MAGNETIC-RESONANCE-IMAGING, MEASUREMENT SCIENCE AND TECHNOLOGY 4 (8) pp. 896-898 IOP PUBLISHING LTD
Bohris AJ, McDonald PJ, Mulheron M (1996) The visualization of water transport through hydrophobic polymer coatings applied to building sandstones by broad line magnetic resonance imaging, JOURNAL OF MATERIALS SCIENCE 31 (22) pp. 5859-5864 CHAPMAN HALL LTD
Etzold MA, McDonald PJ, Routh AF (2014) Growth of sheets in 3D confinements - A model for the C-S-H meso structure, Cement and Concrete Research 63 pp. 137-142
A numerical model for the growth of amorphous quasi-two-dimensional structures in three-dimensional confinements is presented. Application of this model to the formation of calcium-silicate-hydrates by reaction of anhydrous cement and water, within the interstitial pore space of cement grains, leads to structures with growth and morphological properties consistent with a range of experimental data. © 2014 Elsevier Ltd.
MCDONALD PJ, BARKER GJ, CLOUGH S, GREEN RM, HORSEWILL AJ (1986) AN NMR INVESTIGATION OF TUNNELING SIDE-BAND IN DIMETHYL SULFIDE, 2-PENTANONE, 2-HEXANONE AND 2-HEPTANONE USING DOUBLE SIDE-BAND IRRADIATION, MOLECULAR PHYSICS 57 (5) pp. 901-908 TAYLOR & FRANCIS LTD
Karakosta E, Jenneson PM, Sear RP, McDonald PJ (2006) Observations of coarsening of air voids in a polymer-highly-soluble crystalline matrix during dissolution., Phys Rev E Stat Nonlin Soft Matter Phys 74 (1 Pt 1)
A combination of magnetic resonance imaging and x-ray microcomputed tomography has been used to visualize the development of the internal micro-structure within compressed tablets made from a combination of insoluble particles (Eudragit, a polymer) and soluble particles (diltiazem hydrochloride, a drug), during dissolution in water. Air voids in the tablet are seen to coarsen. The size distribution of the air voids is well fitted by a log-normal distribution with a mean size that grows linearly with time. There is evidence for both diffusion of voids and sudden collapse of individual voids, presumably as they coalesce. The behavior of the voids is studied and compared with models of coarsening; the implications for tablet dissolution are considered.
PERRY KL, MCDONALD PJ, RANDALL EW, ZICK K (1994) STRAY FIELD MAGNETIC-RESONANCE-IMAGING OF THE DIFFUSION OF ACETONE INTO POLY(VINYL CHLORIDE), POLYMER 35 (13) pp. 2744-2748 ELSEVIER SCI LTD
Ekanayake P, McDonald PJ, Keddie JL (2009) An experimental test of the scaling prediction for the spatial distribution of water during the drying of colloidal films, EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS 166 pp. 21-27 EDP SCIENCES S A
Keddie JL, Gorce JP, Mallégol J, McDonald PJ (2004) Understanding water-borne coatings: New techniques to answer old questions, Surface Coatings International Part A: Coatings Journal 87 (2) pp. 70-73
Salamanca JM, Ciampi E, Faux DA, Glover PM, McDonald PJ, Routh AF, Peters ACIA, Satguru R, Keddie JL (2001) Lateral drying in thick films of waterborne colloidal particles, LANGMUIR 17 (11) pp. 3202-3207 AMER CHEMICAL SOC
CLOUGH S, HORSEWILL AJ, MCDONALD PJ (1984) METHYL TUNNELLING SPECTROSCOPY AND LEVEL-CROSSING PHENOMENA IN SOLID ACETONE, JOURNAL OF PHYSICS C-SOLID STATE PHYSICS 17 (6) pp. 1115-1125 IOP PUBLISHING LTD
Lloyd CH, Scrimgeour SN, Hunter G, Chudek JA, Lane DM, Mcdonald PJ (1999) Solid state spatially resolved H-1 and F-19 nuclear magnetic resonance spectroscopy of dental materials by stray-field imaging, JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE 10 (6) pp. 369-373 KLUWER ACADEMIC PUBL
BLACK S, LANE DM, MCDONALD PJ, HANNANT DJ, MULHERON M, HUNTER G, JONES MR (1995) THE VISUALIZATION OF THE INGRESS OF POLYMER TREATMENT COATINGS INTO POROUS BUILDING-MATERIALS BY STRAY-FIELD MAGNETIC-RESONANCE-IMAGING, JOURNAL OF MATERIALS SCIENCE LETTERS 14 (17) pp. 1175-1177 CHAPMAN HALL LTD
Keddie JL, Ekanayake P, Koenig AM, Weerakkody TG, Barber N, Johannsmann D, Sear RP, McDonald PJ (2007) Influence of the colloidal stability of latex particles on their distribution in drying films, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 234 AMER CHEMICAL SOC
Ciampi E, van Ginkel M, McDonald PJ, Pitts S, Bonnist EY, Singleton S, Williamson AM (2011) Dynamic in vivo mapping of model moisturiser ingress into human skin by GARfield MRI., NMR Biomed 24 (2) pp. 135-144
We describe the development of in vivo one-dimensional MRI (profiling) using a GARField (Gradient At Right angles to Field) magnet for the characterisation of side-of-hand human skin. For the first time and in vivo, we report measurements of the NMR longitudinal and transverse relaxation parameters and self-diffusivity of the upper layers of human skin with a nominal spatial resolution better than 10 µm. The results are correlated with in vivo confocal Raman spectroscopy measurements of water concentration and natural moisturiser factors, and discussed in terms of known skin biology and microstructure of the stratum corneum and viable epidermis. The application of model moisturiser solutions to the skin is followed and their dynamics of ingress are characterised using the MRI methodology developed. Selected hydrophilic and lipophilic formulations are studied. The results are corroborated by standard in vivo measurements of transepidermal water loss and hydration status. A further insight into moisturisation mechanisms is gained. The effect of two different penetration enhancers on a commonly used skin care oil is also discussed, and different timescales of oil penetration into the skin are reported depending on the type of enhancer.
Etzold MA, McDonald PJ, Faux DA, Routh AF (2015) Filling of three-dimensional space by two-dimensional sheet growth, PHYSICAL REVIEW E 92 (4) ARTN 042106 AMER PHYSICAL SOC
BOOTH S, CLOUGH S, MCDONALD PJ (1984) NMR DOUBLE SIDEBAND SATURATION SPECTROSCOPY, JOURNAL OF PHYSICS C-SOLID STATE PHYSICS 17 (14) pp. L379-L381 IOP PUBLISHING LTD
Lane DM, McDonald PJ (1997) The visualization of spatial gradients in polymer and solvent dynamics for mixed solvents ingressing poly(methyl methacrylate) using stray field magnetic resonance imaging, POLYMER 38 (10) pp. 2329-2335 ELSEVIER SCI LTD
Jones M, Aptaker PS, Cox J, Gardiner BA, McDonald PJ (2012) A transportable magnetic resonance imaging system for in situ measurements of living trees: The Tree Hugger., J Magn Reson 218 pp. 133-140
This paper presents the design of the 'Tree Hugger', an open access, transportable, 1.1MHz (1)H nuclear magnetic resonance imaging system for the in situ analysis of living trees in the forest. A unique construction employing NdFeB blocks embedded in a reinforced carbon fibre frame is used to achieve access up to 210mm and to allow the magnet to be transported. The magnet weighs 55kg. The feasibility of imaging living trees in situ using the 'Tree Hugger' is demonstrated. Correlations are drawn between NMR/MRI measurements and other indicators such as relative humidity, soil moisture and net solar radiation.
McDonald PJ, Mitchell J, Mulheron M, Monteilhet L, Korb JP (2007) Two-dimensional correlation relaxation studies of cement pastes., Magn Reson Imaging 25 (4) pp. 470-473
Two-dimensional nuclear magnetic resonance relaxation correlation studies of cement pastes have been performed on a unilateral magnet, the Surface GARField. Through these measurements, the hydration process can be observed by monitoring the evolution of porosity. Characteristic relaxation time distributions have been observed in different cement pastes: fresh white cement, prehydrated white cement and ordinary Portland cement. The observed T(1)/T(2) ratio in these cements has been shown to agree with expectations based on high field values.
Liu Y, Gajewicz A, Rodin V, Soer W, Scheerder J, Satgurunathan G, McDonald PJ, Keddie JL (2016) Explanations for Water Whitening in Secondary Dispersion and Emulsion Polymer Films, Journal of Polymer Science, Part B: Polymer Physics 54 (16) pp. 1658-1674 Wiley
The loss of optical transparency when polymer films are immersed in water, which is called ?water whitening,? severely limits their use as clear barrier coatings. It is found that this problem is particularly acute in films deposited from polymers synthesized via emulsion polymerization using surfactants. Water whitening is less severe in secondary dispersion polymers, which are made by dispersing solution polymers in water without the use of surfactants. NMR relaxometry in combination with optical transmission analysis and electron microscopy reveal that some of the water sorbed in emulsion polymer films is contained within nano-sized ?pockets? or bubbles that scatter light. In contrast, the water in secondary dispersion polymer films is mainly confined at particle interfaces, where it scatters light less strongly and its molecular mobility is reduced. The addition of surfactant to a secondary dispersion creates a periodic structure that displays a stop band in the optical transmission. The total amount of sorbed water is not a good indicator of polymers prone to water whitening. Instead, the particular locations of the water within the film must be considered. Both the amount of water and the size of the local water regions (as are probed by NMR relaxometry) are found to determine water whitening.
McDonald PJ, Aptaker PS, Mitchell J, Mulheron M (2007) A unilateral NMR magnet for sub-structure analysis in the built environment: the Surface GARField., J Magn Reson 185 (1) pp. 1-11
A new, portable NMR magnet with a tailored magnetic field profile and a complementary radio frequency sensor have been designed and constructed for the purpose of probing in situ the sub-surface porosity of cement based materials in the built environment. The magnet is a one sided device akin to a large NMR-MOUSE with the additional design specification of planes of constant field strength /B0/ parallel to the surface. There is a strong gradient G in the field strength perpendicular to these planes. As with earlier GARField magnets, the ratio G//:B0/ is a system constant although the method of achieving this condition is substantially different. The new magnet as constructed is able to detect signals 50mm (1H NMR at 3.2 MHz) away from the surface of the magnet and can profile the surface layers of large samples to a depth of 35-40 mm by moving the magnet, and hence the resonant plane of the polarising field, relative to the sample surface. The matching radio frequency excitation/detector coil has been designed to complement the static magnetic field such that the polarising B0 and sensing B1 fields are, in principal, everywhere orthogonal. Preliminary spatially resolved measurements are presented of cement based materials, including two-dimensional T1-T2 relaxation correlation spectra.
Benson TB, McDonald PJ, Mulheron M, Nwaubani SO (1998) The use of magnetic resonance imaging techniques in assessing the uptake of surface treatments and water movement through stone faces, MATERIALS AND STRUCTURES 31 (210) pp. 423-427 R I L E M
Hellgren AC, Wallin M, Weissenborn PK, McDonald PJ, Glover PM, Keddie JL (2001) New techniques for determining the extent of crosslinking in coatings, PROGRESS IN ORGANIC COATINGS 43 (1-3) pp. 85-98 ELSEVIER SCIENCE SA
Kowalczyk RM, Gajewicz AM, Mcdonald PJ (2014) The mechanism of water-isopropanol exchange in cement pastes evidenced by NMR relaxometry, RSC Advances 4 (40) pp. 20709-20715
1H nuclear magnetic resonance (NMR) relaxometry shows that arresting the hydration of cement paste by isopropanol exchange does not involve simple replacement of the pore water with isopropanol. Isopropanol fills capillary voids. It removes and replaces the water in the calcium-silicate- hydrate (C-S-H) interhydrate pores. In the C-S-H gel pores, the isopropanol draws water out, but does not replace it to the same extent. The exchange has only a minor impact on C-S-H interlayer water. The connectivity of the interlayer-gel network and interhydrate pores and capillary voids is evidenced by proton-deuteron chemical exchange in the C-S-H pore structure which is observed experimentally for the first time. Isopropanol also reveals the presence of large capillary voids that are not detected in samples saturated with water. This journal is © the Partner Organisations 2014.
Ciampi E, Goerke U, Keddie JL, McDonald PJ (2000) Lateral transport of water during drying of alkyd emulsions, LANGMUIR 16 (3) pp. 1057-1065 AMER CHEMICAL SOC
Ciampi E, McDonald PJ (2003) Skin formation and water distribution in semicrystalline polymer layers cast from solution: A magnetic resonance imaging study, MACROMOLECULES 36 (22) pp. 8398-8405 AMER CHEMICAL SOC
Muller ACA, Scrivener KL, Gajewicz AM, McDonald PJ (2013) Densification of C-S-H measured by H NMR relaxometry, Journal of Physical Chemistry C 117 (1) pp. 403-412 American Chemical Society
The nanoscale morphology of, and pore water interactions in, calcium silicate hydrate (C-S-H), the active component of cement, remain uncertain. H nuclear magnetic resonance (NMR) can fully characterize the nanoporosity of C-S-H in as-prepared material without the need for damaging sample drying. We use NMR to follow the density of C-S-H in sealed cured pastes as a function of degree of hydration (±) and water to cement ratio. We show clear evidence for C-S-H densification. The C-S-H "solid" density, exclusive of gel pore water, slightly decreases from Á = 2.73 g/cm at ± H 0.4 to 2.65 g/cmat ± H 0.9 due to an increase in the number of layers in the nanocrystalline aggregates. In the same range, the C-S-H "bulk" density, including gel water, increases from around 1.8 to 2.1 g/cm. The increase corresponds to a transition from growth of low-density product containing gel pores to higher density product devoid of gel pores. We update Powers' classical model from 1947. In contrast to the single "hydrate" of Powers, NMR differentiates between C-S-H and calcium hydroxide and separates out the interlayer water within the C-S-H. It shows a clear nonlinearity in the growth of the different fractions with ±. © 2012 American Chemical Society.
BENSON TB, MCDONALD PJ (1995) PROFILE AMPLITUDE-MODULATION IN STRAY-FIELD MAGNETIC-RESONANCE-IMAGING, JOURNAL OF MAGNETIC RESONANCE SERIES A 112 (1) pp. 17-23 ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS
McDonald PJ, Turner MN (2015) Combining effective media and multi-phase methods of Lattice Boltzmann modelling for the characterisation of liquid-vapour dynamics in multi-length scale heterogeneous structural materials, MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING 24 (1) ARTN 015010 IOP PUBLISHING LTD
Korb J-P, Monteilhet L, McDonald PJ, Mitchell J (2007) Microstructure and texture of hydrated cement-based materials: A proton field cycling relaxometry approach, CEMENT AND CONCRETE RESEARCH 37 (3) pp. 295-302 PERGAMON-ELSEVIER SCIENCE LTD
Newling B, Glover PM, Keddie JL, Lane DM, McDonald PJ (1997) Concentration profiles in creaming oil-in-water emulsion layers determined with stray field magnetic resonance imaging, Langmuir 13 (14) pp. 3621-3626
We report the first use of stray field magnetic resonance imaging in the determination of concentration profiles in layers (with submillimeter thickness) of coarse oil-in-water emulsions that are undergoing creaming. We compare our results for emulsions having various oil contents to the predictions of a numerical model. In emulsions having low oil content (12 and 23 vol %), we find that the model adequately predicts the profile shape and time-dependent change in the lower region of the emulsion. In the cream layer at the top of each of the samples, however, the predictions of the model deviate substantially from the observed profiles. Whereas the model assumes that the concentration of oil in the cream layer is constant as the layer increases in thickness, we observe that there is a concentration gradient in the cream layer and that the concentration of oil in the layer increases with time. In explaining our findings, we consider the effects of polydispersity and the presence of gum xanthan in the continuous phase and also the possibility of gradual compaction of oil droplets in the cream layer (a phenomenon not considered in the model).
McDonald PJ, Newling B (1998) Stray field magnetic resonance imaging, REPORTS ON PROGRESS IN PHYSICS 61 (11) pp. 1441-1493 IOP PUBLISHING LTD
CLOUGH S, HORSEWILL AJ, MCDONALD PJ, ZELAYA FO (1985) MOLECULAR TUNNELING MEASURED BY DIPOLE-DIPOLE - DRIVEN NUCLEAR MAGNETIC-RESONANCE, PHYSICAL REVIEW LETTERS 55 (17) pp. 1794-1796 AMERICAN PHYSICAL SOC
Laity PR, Glover PM, Godward J, McDonald PJ, Hay JN (2000) Structural studies and diffusion measurements of water-swollen cellophane by NMR imaging, CELLULOSE 7 (3) pp. 227-246 KLUWER ACADEMIC PUBL
Hopkinson I, Jones RAL, Black S, Lane DM, McDonald PJ (1997) Fickian and Case II diffusion of water into amylose: a stray field NMR study, CARBOHYDRATE POLYMERS 34 (1-2) pp. 39-47 ELSEVIER SCI LTD
McDonald PJ, Pritchard T, Roberts SP (1996) Diffusion of water at low saturation levels into sandstone rock plugs measured by broad line magnetic resonance profiling, JOURNAL OF COLLOID AND INTERFACE SCIENCE 177 (2) pp. 439-445 ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS
Fischer N, Haerdtl R, McDonald PJ (2015) Observation of the redistribution of nanoscale water filled porosity in cement based materials during wetting, Cement and Concrete Research 68 pp. 148-155
© 2014 Elsevier Ltd.Spatially resolved GARField NMR has been used to follow the ingress of water into previously dried Portland cement concrete and mortar samples. It is shown that the amount of capillary water in the surface layers of different samples after 1 day of capillary absorption exceeds the amount found before drying but that over the subsequent 7 days the amount of capillary water decreases once more, even though the external source of water is maintained. The hydrate gel pore water was additionally tracked in the mortars. It shows complementary behaviour. The data is discussed in terms of C-S-H swelling.
Lloyd CH, Scrimgeour SN, Lane DM, Hunter G, McDonald PJ (2001) The application of magnetic resonance microimaging to the visible light curing of dental resins - 3. Stray-field nuclear magnetic resonance imaging (STRAFI), DENTAL MATERIALS 17 (5) pp. 381-387 ELSEVIER SCI LTD
Faux DA, McDonald PJ, Cachia S-H, Howlett N, Etzold M, Routh A (2015) New nanoscale models for water in cement-based materials,
Valori A, McDonald PJ, Scrivener KL (2013) The morphology of C-S-H: Lessons from H nuclear magnetic resonance relaxometry, Cement and Concrete Research 49 pp. 65-81 Elsevier
H nuclear magnetic resonance has been applied to cement pastes, and in particular calcium silicate hydrate (C-S-H), for the characterisation of porosity and pore water interactions for over three decades. However, there is now renewed interest in the method, given that it has been shown to be non-invasive, non-destructive and fully quantitative. It is possible to make measurements of pore size distribution, specific surface area, C-S-H density and water fraction and water dynamics over 6 orders of magnitude from nano- to milli-seconds. This information comes in easily applied experiments that are increasingly well understood, on widely available equipment. This contribution describes the basic experiments for a cement audience new to the field and reviews three decades of work. It concludes with a summary of the current state of understanding of cement pore morphology from the perspective of H NMR. © 2013 Elsevier Ltd. All rights reserved.
McDonald PJ, Rodin V, Valori A (2010) Characterisation of intra- and inter-C-S-H gel pore water in white cement based on an analysis of NMR signal amplitudes as a function of water content, CEMENT AND CONCRETE RESEARCH 40 (12) pp. 1656-1663 PERGAMON-ELSEVIER SCIENCE LTD
MCDONALD PJ, VIJAYARAGHAVAN D, DEBENHAM PM, HORSEWILL AJ (1993) PRESSURE-DEPENDENCE OF METHYL TUNNELING IN SOLID DIACETYL - AN EXTENSION TO THE METHYL THERMOMETER MODEL, MOLECULAR PHYSICS 78 (1) pp. 219-228 TAYLOR & FRANCIS LTD
Faux DA, McDonald PJ, Howlett N (2017) Nuclear magnetic resonance relaxation due to the translational diffusion of fluid confined to quasi-two-dimensional pores, Physical Review E 95 (3) 033116 American Physical Society
Nuclear magnetic resonance (NMR) relaxation experimentation is an e ective technique for non-destructively probing the dynamics of proton-bearing uids in porous media. The frequencydependent relaxation rate T?1 1 can yield a wealth of information on the uid dynamics within the pore provided data can be t to a suitable spin di usion model. A spin di usion model yields the dipolar correlation function G(t) describing the relative translational motion of pairs of 1H spins which then can be Fourier transformed to yield T?1 1 . G(t) for spins con ned to a quasi-two-dimensional (Q2D) pore of thickness h is determined using theoretical and Monte Carlo techniques. G(t) shows a transition from three- to two-dimensional (2D) motion with the transition time proportional to h2. T?1 1 is found to be independent of frequency over the range 0.01{100 MHz provided h ? 5 nm and increases with decreasing frequency and decreasing h for pores of thickness h
Faux DA, McDonald PJ (2017) Explicit calculation of nuclear magnetic resonance relaxation rates in small pores to elucidate molecular scale fluid dynamics, Physical Review E: Statistical, Nonlinear, and Soft Matter Physics 95 (3) 03117 American Physical Society
Nuclear magnetic resonance (NMR) spin-lattice (T?1 1 ) and spin-spin (T?1 2 ) relaxation rate mea- surements can act as e ective non-destructive probes of the nano-scale dynamics of 1H spins in porous media. In particular, fast- eld-cycling T?1 1 dispersion measurements contain information on the dynamics of di using spins over time scales spanning many orders of magnitude. Previously- published experimental T?1 1 dispersions from a plaster paste, synthetic saponite, mortar and oil- bearing shale are re-analysed using a model and associated theory which describe the relaxation rate contributions due to the interaction between spins ensembles in quasi-two-dimensional (Q2D) pores. Application of the model yields physically-meaningful di usion correlation times for all systems. In particular, the surface di usion correlation time and the surface desorption time take similar values for each system suggesting that surface mobility and desorption are linked processes. The bulk uid di usion correlation time is found to be 2-5 times the value for the pure liquid at room temperature for each system. Re-analysis of the oil-bearing shale yields di usion time constants for both the oil and water constituents. The shale is found to be oil-wetting and the water T?1 1 dispersion is found to be associated with aqueous Mn2+ paramagnetic impurites in the bulk water. These results escalate the NMR T?1 1 dispersion measurement technique as the primary probe of molecular-scale dynamics in porous media yielding di usion parameters and a wealth of information on pore morphology.
Muller A, Scrivener K, Gajewicz A, McDonald PJ (2013) Use of bench-top NMR to measure the density, composition and desorption isotherm of C-S-H in cement paste, Microporous and Mesoporous Materials 178 pp. 99-103
H nuclear magnetic resonance (NMR), supported by a measurement of the degree of hydration using X-ray diffraction, has been used to fully characterise the nano-scale porosity and composition of calcium-silicate-hydrate (C-S-H), the active component of cement. The resultant "solid" density and composition are Á = 2.68 g/cm; (Ca). (Si,Al)O. (HO) for an underwater cured, never-dried cement paste with an initial mix water-to-cement ratio of 0.4 after 28 days of hydration. In addition, the first pore-type resolved desorption isotherm of cement that shows the location of water as a function of relative humidity has been measured. Critical to our results is verification of the assignment of the different NMR spin-spin relaxation time components. These have been corroborated with conventional analyses. The new methodology is key to enabling design of cement pastes with lower environmental impact.
Yermakou V (2017) Study of the transport of water in the nanopores of C?S?H by 1H NMR.,
This thesis describes a series of 1H nuclear magnetic resonance (NMR) experiments to investigate connectivity of the the nanopores of the calcium-silicate-hydrates (C?S?H) in cement based materials. This is achieved by coupling 1H NMR relaxometry in one and two relaxation times dimensions and 1H NMR cryoporometry down to about -80C. In particular the thesis contains the first use in any system of coupled two dimensional relaxometry and low temperature cryoporometry.
The cryoporometry has been validated on model porous silica glass (SiO2) materials with known pore sizes and then applied to C2S and C3S, in cement chemistry notation, otherwise known as alite and belite. The 1H NMR cryoporometry data was used to estimate the pore sizes in C2S. It was found that the T2 relaxation time depends on temperature in C2S and C3S, but not in porous glasses SIO2 and MCM-41. There are two possible explanations. It could be due to the interaction of water with the -OH groups on the pore surface. It is known, that water, or a monolayer of water becomes physisorbed on silanol groups. Silanol groups are present both at the silica glasses surfaces as well at the cement pores surfaces. However, there are no many studies available on the interaction of water-silanol groups and temperature dependency below 0C. The other explanation concerns hydrated calcium ions in cementitious materials not present in silica glasses. However, little is known about C?S?H surfaces.
A two dimensional 1H NMR T2 ? T2 exchange experiment was used to investigate the exchange of water between interlayer spaces, gel pores and capillary pores at temperatures of room temperature, -5C and -30C on cooling and again on warming in C3S. A 3- site exchange numerical model was written to solve the associated coupled differential magnetisation exchange equations. By comparing the model output and experimental data it was shown that water exchanges between interlayer spaces and gel pores and between interlayer spaces and capillary pores. However, there is no exchange from gel pores to capillary pores.
A further set of room temperature experiments were carried out to investigate the change in the pore size distribution of C-S-H in white cement following desorption and resorption of water as a function of drying severity. Rearrangements of the nano porosity were seen dependant on the severity of the drying. There were both reversible and irreversible changes. However, the total pore volume remained constant within m
Faux DA, McDonald PJ (2017) A model for the interpretation of nuclear magnetic
resonance spin-lattice dispersion measurements on
mortar, plaster paste, synthetic clay and oil-bearing
shale,
Microporous and Mesoporous Materials Elsevier
A model linking the molecular-scale dynamics of fluids confined to nano-pores to nuclear magnetic resonance (NMR) relaxation rates is proposed. The model is used to re-analyse fast field-cycling spin-lattice relaxation rate measurements for the separate water and oil dispersions from an oil-bearing shale [Korb et al., J. Phys. Chem. C, 118, 199 (2014)]. The model assumes that pore fluid can be characterized by three time constants: the surface and bulk diffusion correlation times and a surface desorption time constant. Results are shown to yield meaningful and consistent intra-pore dynamical time constants, insight into diffusion mechanisms and pore morphology. The shale is found to be oil-wetting and the water dispersion is found to be due to the interaction of aqueous Mn2+ ions with bulk water spins. Clay, mortar and plaster paste dispersions measurements have also been successfully re-analysed and a summary of the results is presented. The results demonstrate the wide applicability of the model which advances NMR dispersion experimentation as a powerful tool for measuring nano-porous fluid properties.
Wyrzykowski M, McDonald P, Scrivener K, Lura P (2017) Water Redistribution within the Microstructure of Cementitious Materials due to Temperature Changes Studied with 1H NMR, Journal of Physical Chemistry C 121 (50) pp. 27950-27962 American Chemical Society
Changes of water state within the pore structure of cement paste due to temperature changes are followed by means of 1H-proton nuclear magnetic resonance (NMR) relaxation analysis. The study shows that with increasing temperature, the signal due to water contained in the smallest C-S-H interlayer spaces decreases while that from the larger gel pores, and to a lesser extent from the capillary pores, increases. On cooling, the opposite behavior is observed with complete reversibility. The observed changes in water populations appear to be instantaneous compared to the rate of temperature change in the samples. These changes are postulated to be responsible for macroscopically observed changes of relative humidity in pores during heating/cooling and are therefore key in understanding thermal deformations of cement based materials. It is evident that the previous hypothesis of microstructural delayed water transport being responsible for macrostructural delayed thermal deformations can be rejected. Different microstructural mechanisms are discussed that could explain the redistribution in water signals, namely water migration and pore rearrangement mechanisms.
Ibrahim M, Pardi C, Brown T, McDonald P (2018) Active elimination of radio frequency interference for improved signal-to-noise ratio for in-situ NMR experiments in strong magnetic field gradients, Journal of Magnetic Resonance 287 pp. 99-109 Elsevier
Improvement in the signal-to-noise ratio of Nuclear Magnetic Resonance (NMR) systems may be achieved either by increasing the signal amplitude or by decreasing the noise. The noise has multiple origins ? not all of which are strictly ?noise?: incoherent thermal noise originating in the probe and pre-amplifiers, probe ring down or acoustic noise and coherent externally broadcast radio frequency transmissions. The last cannot always be shielded in open access experiments. In this paper, we show that pulsed, low radio-frequency data communications are a significant source of broadcast interference. We explore two signal processing methods of de-noising short