Study of Pumpkin Drying Through Magnetic Resonance Imaging

Appropriate drilling fluid additives which can build effective filter cakes are key components to minimize formation damage. Today there exists no effective and quantitative technique which can assess the formation damage minimization potential of any novel drilling fluid. This study provides the methodology for such a technique, by integrating HP/HT fluid loss data, derived from standard API HP/HT filter press, with filter cake quality and filtrate penetration depth, derived by Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) techniques. Novel nano-based drilling fluidwas made of de-ionized water, 7 wt% commercial Na-bentonite, and addition of custom made iron oxide (CM Fe3O4) nanoparticles (NP) at 0.5 wt%. Its excellent filtration characteristics were determined at elevated pressures and temperatures using a HP/HT filter press (500 psi/350°F) with ceramic discs, mimicking the formation, as filter media of k=775 mD. NMR T2 relaxation time measurements provided the pore size distribution of the ceramic discs, and a newly developed MRI technique by our team allowed direct visualization on the core-ceramic disc of the produced filter cake and filtrate penetration depth, providing insights on filtration characteristics. Addition of 0.5 wt% Fe3O4 NP resulted in a decrease of fluid loss by 47% compared to that obtained from the base fluid (BF) without the nanoparticles. The excellent filtration characteristics were attributed to the synergistic interaction of NP with bentonite platelets producing a strong microstructure network leading to rigid and very low permeability filter cakes. Spin-spin relaxation time (T2) NMR measurements revealed different pore size distribution of the nano-enhanced drilling fluid showing its tendency to occupy the smallest pores of the filter medium (ceramic disc). MRI T2 measurements revealed the saturation profiles of the drilling fluids inside the ceramic discs, in 3-D space. This allowed the visual representation of the penetration depth of the filtrate produced in the ceramic discs of the different tested drilling fluids. Our integrated characterization approach, gives us tools to analyze inter-particle interactions in the filter cakes at HP/HT conditions in order to explain the significant improvement in fluid loss performance of novel drilling fluids. The information gained in this study is considered to be extremely significant for deriving an effective methodology for assessing formation damage potential of any newly developed drilling fluid which can lead to more efficient and cost-effective drilling activities.

A nuclear magnetic resonance advance. Imaging fluorinated anesthetics in the brain.

Nuclear magnetic resonance (NMR) and nuclear magnetic resonance imaging (MRI) techniques are described in relation to applications on intact plants. These techniques are non-destructive and non-invasive and can be used to study the dynamics of plant water relations and water transport, e.g., as a function of environmental (stress) conditions. Non-spatially resolved NMR as well as two-dimensional or even three-dimensional imaging strategies can be applied. The relevant NMR parameters that can be used to discriminate between water in sub-cellular compartments are the relaxation times T 1 and T 2, and (restricted) diffusion. The information within MRI images can be manipulated in such a way that in addition to anatomical information physico-chemical information like cell compartment size, water membrane permeability, water diffusion and flow, information on chemical composition (water, oils, sugars and other metabolites) are obtained. This information is also available in non-spatially resolved NMR with a much higher signal-to-noise ratio, but the interpretation of such non-spatially resolved measurements can be hampered by heterogeneity of the plant tissue (sub-cellular compartments, tissue heterogeneity and different types of tissue). Here we present a number of 1H NMR and MRI techniques that can be used to study plant performance in relation to its photosynthetic activity. In addition, dedicated hardware for intact plant studies is discussed.

In the last few years there has been rapid progress in the application of nuclear magnetic resonance clinical imaging as a diagnostic aid (Partain et al, 1983; Steiner, 1983; Worthington, 1983). Records kept by the operators of NMR imaging equipment indicate that about 1800 individuals have now been examined without incident within the United Kingdom. In view of this progress, an advisory group (Appendix) appointed by the National Radiological Protection Board recommends some modifications to the original advice given in 1981 (NRPB, 1981). The principal modifications are that: (1) It is no longer considered necessary to exclude volunteers with a history of epilepsy or cardiac disease. (2) It is not obligatory that a registered medical practitioner trained in resuscitation techniques be present during an exposure. (3) Higher limits are recommended for rates of change of magnetic flux density when the period of change is less than 10 ms. (4) The radiofrequency limit of 15 MHz has been removed. Theoretical considerations indicate that the interaction of an applied magnetic field with the intrinsic magnetic moments of protons and electrons within a molecule could alter its rate of chemical reaction (McLauchlan, 1981). Chemical reactions involving radical pair intermediates are expected to be sensitive to magnetic fields for this reason and a number of enzyme reactions that might be expected to be affected have been identified (A. Cass, personal communication). However, there is no experimental confirmation of these theoretical possibilities at present.

Many aspects of the use of high-resolution nuclear magnetic resonance (NMR) imaging in the examination of brain edema have not been fully explored. These include the quantitation of edema fluid, the ability to distinguish between various types of edema, and the extent to which tissue changes other than a change in water content can affect NMR relaxation times. The authors have compared NMR relaxation times obtained by both in vivo magnetic resonance imaging (MRI) and in vitro NMR spectroscopy of brain-tissue samples from young adult rats with cold lesions, fluid-percussion injury, hypoxic-ischemic injury, bacterial cerebritis, and cerebral tumor. Changes in relaxation times were compared with changes in brain water content, cerebral blood volume, and the results of histological examination. In general, both in vivo and in vitro longitudinal relaxation times (T1) and transverse relaxation times (T2) were prolonged in the injured hemispheres of all experimental groups. Water content of tissue from the injured hemispheres was increased in all groups. A linear correlation between T2 (but not T1) and water content was found. Changes in the values of T1 and T2 could be used to distinguish tumor from cold-injured tissue. Cerebral blood volume was reduced in the injured hemispheres and correlated inversely with prolongation of T1 and T2. The results of this study suggest that, in a clinical setting, prolongation of T2 is a better indicator of increased water content than prolongation of T1, yet quantitation of cerebral edema based solely upon prolongation of in vivo or in vitro T1 and T2 should be undertaken with caution.

During the past decade, the application of nuclear magnetic resonance (NMR) imaging techniques to problems of relevance to the process industries has been identified. The particular strengths of NMR techniques are their ability to distinguish between different chemical species and to yield information simultaneously on the structure, concentration distribution and flow processes occurring within a given process unit. In this paper, examples of specific applications in the areas of materials and food processing, transport in reactors and two-phase flow are discussed. One specific study, that of the internal structure of a packed column, is considered in detail. This example is reported to illustrate the extent of new, quantitative information of generic importance to many processing operations that can be obtained using NMR imaging in combination with image analysis.

Water status and distribution in shiitake mushroom and the effects of drying temperature on water migration were investigated by low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) technique. Three water components assigned to bound, immobilized water and free water were observed in fresh shiitake mushroom by LF-NMR, and higher moisture content was found in the lamella and outer layer of stalk by MRI. During drying, the transverse relaxation time and peak area of immobilized and free water in pileus significantly decreased. Higher drying temperature could promote the changes in water mobility and population. MRI results revealed the water evaporated from external surface of shiitake mushroom, then the water in inner region migrated to the surface during the drying. The drying properties, color and shrinkage of shiitake mushroom were also measured. The strong correlation between moisture content and total peak area of water with a coefficient of 0.9792 revealed the potential of LF-NMR as a rapid and nondestructive method to monitor drying degree of shiitake mushroom.

Application of nuclear magnetic resonance (NMR) imaging, with analysis of grey levels in the images, provides a semi-quantitative non-destructive estimation of the extent of whisker distribution in the green state composites. Regions with large physical flaws caused by hard particles or open pores may be identified. Examination of the composite after sintering, by scanning electron microscopy (SEM) and energy dispersive analysis of X-rays, confirmed that the areas of high grey levels in the NMR images were mainly caused by whisker bundles. However, individual flaws smaller than the detection limit (100 μm) of the NMR imaging technique were also observed during the SEM analysis of the sintered sample.

With the recent development of nuclear magnetic resonance (NMR) imaging it is important to characterise and understand the NMR response of tissues. There are several reasons why such characterisation of tissues using NMR parameters would be useful. It may provide a helpful diagnostic guide and could lead to a deeper understanding of the underlying processes responsible for many pathological and physiological states of tissues. For several years, hydrogen density, spin-lattice relaxation and spin-spin relaxation maps of objects have been obtained using the NMR imaging technique. The authors have developed a method for the spatial mapping of an additional NMR parameter, the molecular translational diffusion coefficient D. In addition the technique will permit the measurement of perfusion and blood flow rates.

There are many nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) techniques that employ resistive magnets. Resistive magnets are particularly useful for low‐field (<0.5 T) imaging and for applications involving the cycling of magnetic fields. This article discusses a general technique for the fabrication of resistive magnets that can be used in small animal MR imaging. A detailed discussion is given of the magnet winding technique, the forced‐water cooling system design and construction, and the support structure. Two examples are given of resistive systems built by the authors. © 2006 Wiley Periodicals, Inc. Concepts Magn Reson 29B: 168–175, 2006.

Bertram Schwarzschild described the important contributions made by the 2003 Nobel laureates Paul Lauterbur and Peter Mansfield during the 1970s (Physics Today, December 2003, page 24). They extended magnetic resonance imaging for applications in medicine into two and three dimensions and to faster speeds. Schwarzschild refers to an article by Felix Wehrli (Physics Today, Physics Today 0031-9228 45 6 1992 34 https://doi.org/10.1063/1.881310. June 1992, page 34 ), but Wehrli makes no mention of the earlier use of magnetic field gradients and MRI during the 1950s and 1960s (see Physics Today, January 1993, page 94).Schwarzschild does mention the early use of magnetic field gradients to correlate the nuclear signal (usually proton) with spatial coordinates. He cites work by Erwin Harm and by Edward Purcell and me, 1 1. E. L. Hahn, Phys. Rev. 80, 580 (1950); https://doi.org/10.1103/PhysRev.80.580 H. Y. Carr, E. M. Purcell, Phys Rev. 94, 630 (1954). https://doi.org/10.1103/PhysRev.94.630 but that work is not directly related to internal macroscopic imaging. Hahn used existing gradients to observe diffusion, while Purcell and I intentionally applied additional gradients to study diffusion. For modern internal MRI, another component in addition to the applied gradient is necessary. Unlike for diffusion or flow studies, the object being observed must have spatially inhomogeneous internal structure. To the best of my knowledge, the first time such a field gradient was applied to a nuclear magnetic resonance (NMR) sample having an inhomogeneously distributed internal spin system was during a demonstration I conducted for my PhD thesis. 2 2. H. Y. Carr, “Free Precession Techniques in Nuclear Magnetic Resonance,” PhD thesis, Harvard U., Cambridge, MA (1952); Encyclopedia of Nuclear Magnetic Resonance, vol. 1, Wiley and Sons, Hoboken, NJ (1996), p. 253. My motivation in that demonstration was to help faculty and other graduate students understand the recently discovered and rather complicated NMR fine structure in ethyl alcohol. A special object, built for the demonstration, consisted initially of two and later three small separated groups of protons having numbers of protons in the ratios of 3:2:1. The groups were placed in a straight line parallel to the direction of the magnetic field gradient. Thus that first MRI image or spin map was one-dimensional. Although medical applications for 1D imaging are very few, in physics there are several; the most notable was in the discovery of superfluid helium-3. The 1952 demonstration used the new and faster pulsed NMR technique 3 3. D. D. Stark, W. G. Bradley, Magnetic Resonance Imaging, C. V. Mosby, St. Louis, MO (1988), p. 9. rather than the simpler and slower continuous-wave frequency (or field) sweep technique. 4 4. C. Leon Partain et al. , Nuclear Magnetic Resonance (NMR) Imaging, W. B. Saunders, Philadelphia (1983), chap. 17. The visual observation of the three separated groups of protons provided confidence in the pulsed MRI technique with its spatial image coming from the Fourier transform of the complicated time-dependent free-induction decay. That first MRI demonstration was not reported in the 1954 paper, which concentrated on the basic techniques of the new pulsed NMR used with internally homogeneous samples. Other topics, including gradient echoes, electric shims, and the spinning of the samples to obtain narrower lines for observing very fine structure, were left for later papers.My thesis received significant distribution. In particular, Nuclear Magnetic Resonance Specialties near Pittsburgh, Pennsylvania, where Lauterbur and Raymond Damadian did their initial MRI work, received a copy in 1967. Shortly thereafter, the president of the company requested additional copies for some of the purchasers of the company’s pulsed NMR spectrometers.REFERENCESSection:ChooseTop of pageREFERENCES <<CITING ARTICLES1. E. L. Hahn, Phys. Rev. 80, 580 (1950); https://doi.org/10.1103/PhysRev.80.580 , Google ScholarCrossref, ISI H. Y. Carr, E. M. Purcell, Phys Rev. 94, 630 (1954). https://doi.org/10.1103/PhysRev.94.630 , , Google ScholarCrossref, ISI2. H. Y. Carr, “Free Precession Techniques in Nuclear Magnetic Resonance,” PhD thesis, Harvard U., Cambridge, MA (1952); Google Scholar Encyclopedia of Nuclear Magnetic Resonance, vol. 1, Wiley and Sons, Hoboken, NJ (1996), p. 253. Google Scholar3. D. D. Stark, W. G. Bradley, Magnetic Resonance Imaging, C. V. Mosby, St. Louis, MO (1988), p. 9. Google Scholar4. C. Leon Partain et al. , Nuclear Magnetic Resonance (NMR) Imaging, W. B. Saunders, Philadelphia (1983), chap. 17. Google Scholar© 2004 American Institute of Physics.

HomeRadiologyVol. 231, No. 3 PreviousNext EditorialsMR Imaging: Its Development and the Recent Nobel PrizeStephen J. RiedererStephen J. RiedererAuthor Affiliations1From the MR Laboratory, Mayo Clinic, 200 First Street SW, Rochester, MN 55905. Received January 19, 2004; accepted January 21. Address correspondence to the author (e-mail: [email protected]).Stephen J. RiedererPublished Online:Jun 1 2004https://doi.org/10.1148/radiol.2313040114MoreSectionsFull textPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In References 1 Lauterbur PC. Image formation by induced local interactions: examples employing nuclear magnetic resonance. Nature 1973; 242:190-191. Crossref, Google Scholar2 USA MRI market Mountain View, Calif: Frost and Sullivan Market Research, 2002. Google Scholar3 Mansfield P, Grannell PK. NMR “diffraction” in solids? J Phys C Solid State Phys 1973; 6:L422. Crossref, Google Scholar4 Mansfield P. 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Computerized fluoroscopy in real time for noninvasive visualization of the cardiovascular system: preliminary studies. Radiology 1979; 130:49-57. Link, Google ScholarArticle HistoryPublished in print: June 2004 FiguresReferencesRelatedDetailsCited ByMedicine, Vol. 93, No. 28Skeletal Radiology, Vol. 40, No. 9Medicine - Programa de Formaci?n M?dica Continuada Acreditado, Vol. 9, No. 92Magnetic Resonance Imaging, Vol. 24, No. 4Applied Magnetic Resonance, Vol. 29, No. 1Pacing and Clinical Electrophysiology, Vol. 28, No. 10Magnetic Resonance Imaging, Vol. 22, No. 10Recommended Articles RSNA Education Exhibits RSNA Case Collection Vol. 231, No. 3 Metrics Altmetric Score PDF download

Paul Christian Lauterbur

The dynamic spiral nuclear magnetic resonance (NMR) imaging technique was used to investigate the water imbibition into cellulose fiber matrices. The advancing water boundary, water concentration distribution, and swelling degree within the fiber matrix samples were monitored as a function of time over the entire absorption process. A combined image that shows the time evolution of the absorbed water concentration distribution within the fiber matrix was synthesized from the dynamically acquired NMR image data set. The NMR imaging data clearly demonstrated that water imbibition into a fiber matrix consists of two different processes: water penetration into capillaries between fibers and water diffusion into the cellulose fibers. The advancing liquid front is primarily determined by the water capillary flow and can be quantitatively described by Washburn equation. The slower water diffusion process in fibers is mainly responsible for the fiber swelling. The time evolution of the absorbed water concentration distribution can be qualitatively interpreted in terms of steady capillary flow and concentration-gradient-driven diffusion into fibers with a constant permeability. The effects of pore morphology, tortuosity, and surface heterogeneity to the water absorption process are also discussed.

Possible optimisation of pastes and the according apparatus in process engineering by MRI flow experiments