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  • 1
    Electronic Resource
    Electronic Resource
    An NMR pulsed field gradient study of the electrical and conventional heating of carrot (1995)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of food science & technology 30 (1995), S. 0 
    Details
    ISSN: 1365-2621
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experiments have been carried out using pulsed field gradient NMR to characterize the self-diffusion of water within samples of carrot, both uncooked and cooked by either volumetric electrical or conventional heating. The method detected the presence of structure within uncooked carrot, and the disappearance of the structure on cooking. The NMR data were fitted to two models: (i) an analytical solution for diffusion between impermeable barriers and (ii) a numerical solution to the more physically realistic situation of diffusion between permeable barriers. The barrier spacings obtained with raw carrot data using both methods (i) and (ii) were consistent with cell sizes found in carrots. The effect of cooking on the model fit was either an increase in barrier spacing (method i), or an increase in barrier permeability (method ii). There was a statistically significant difference between samples cooked electrically and conventionally, but this was much less than the difference between cooked and uncooked material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1995.tb01411.x
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  • 2
    Electronic Resource
    Electronic Resource
    NMR imaging of the wheat grain cooking process (1997)
    Oxford, UK : Blackwell Science Ltd
    International journal of food science & technology 32 (1997), S. 0 
    Details
    ISSN: 1365-2621
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: NMR imaging has been used to study the boiling and steaming of intact wheat grains by mapping the distribution of water on the central cross section of grains after various cooking times. The results show different distributions of water occurring with boiling and steaming. Boiled grains showed a front of moisture which gradually moved towards the centre of the grain, although some water was able to diffuse ahead of the front. Steamed grains showed no such front, but showed a homogeneous distribution of water which gradually increases with cooking time. The different results for boiling and steaming imply that different mechanisms control the influx of water in each case, and provide important data for modelling these processes. It is postulated that absorption of water during steaming is slowed by the grain temperature rising above that of the steam temperature as a result of the latent heat associated with the condensation of steam being taken up by the grain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2621.1997.00122.x
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  • 3
    Electronic Resource
    Electronic Resource
    A differential scanning calorimetry study of wheat grain cooking (1997)
    Oxford, UK : Blackwell Publishing Ltd
    International journal of food science & technology 32 (1997), S. 0 
    Details
    ISSN: 1365-2621
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary  A number of commercial processes involve whole grain cooking. In this study, differential scanning calorimetry (DSC) scans were taken of whole wheat grains that had been boiled or steamed for various times at either 100 d̀C or 120 d̀C. Scans were also taken of raw grains that had been soaked and equilibrated to different moisture contents. Raw grains showed peak temperatures to be dependent on moisture content, in close agreement with literature data for wheat starch/water mixtures. The two cooking methods showed different behaviour, which can be explained with reference to magnetic resonance imaging (MRI) (Stapley et al., 1997). For steamed grains with high moisture contents at longer cooking times, part of the DSC endotherm was below the cooking temperature, and conversion occurred in the cooker. DSC endotherms of steamed grains showed a clearly denned onset temperature, c. 6d̀C above the steam temperature, due to the release of latent heat. MRI shows partially boiled grains to have a high moisture content in the outer regions and an inner core of lower moisture content. The peak temperatures observed by DSC were similar to those expected of soaked grains with the same moisture contents as that of the core. It is postulated that the inner core contains unconverted starch, and that conversion has been achieved in the outer regions. The specific heat capacity for each grain was also measured, and correlated well with moisture content, but was not strongly influenced by the grain treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1997.tb02121.x
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  • 4
    Electronic Resource
    Electronic Resource
    Applications of in situ magnetic resonance techniques in chemical reaction engineering (1999)
    Springer
    Topics in catalysis 8 (1999), S. 87-95 
    Details
    ISSN: 1572-9028
    Keywords: nuclear magnetic resonance (NMR) ; pulsed gradient spin echo (PGSE) ; magnetic resonance imaging (MRI) ; catalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract NMR spectroscopy is now a well‐established technique for the in situ study of surface chemistry and the chemical processes occurring during catalytic reactions. Developments in probe design are making the sample environments ever closer to the operating conditions of the catalyst in industrial use. In parallel with these advances there is an increasing interest in the application of field gradient magnetic resonance techniques, namely pulsed gradient spin echo (PGSE) NMR and magnetic resonance imaging (MRI), to in situ studies of mass transport processes in catalysts and reactors. An overview of the recent developments in in situ NMR spectroscopy, PGSE NMR and MRI studies in application to catalysis and reaction engineering is presented and the potential of these techniques in the numerical modelling of catalytic processes and reactor design is highlighted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019180220757
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  • 5
    Electronic Resource
    Electronic Resource
    Quantitative nuclear magnetic resonance imaging of liquids in swelling polymers (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1795-1806 
    Details
    ISSN: 0887-624X
    Keywords: NMR imaging ; NMR relaxation ; ultra-high molecular weight polyethylene ; Fickian diffusion ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The variation of nuclear magnetic resonance (NMR) relaxation parameters (T1, T2) within a polymer during swelling, limits the absolute accuracy with which liquid concentration profiles can be obtained using NMR imaging. In this article a study of the diffusion of decalin into ultra-high molecular weight polyethylene (UHMWPE) is reported. The study illustrates the use of a method of analysis whereby quantitative solvent profiles can be obtained from data influenced by both T1 and T2 contrast effects. A T1 and T2 map are obtained at a point in the uptake of liquid where the greatest range in liquid concentration is obtained at a point in the uptake of liquid where the greatest range in liquid concentration is observed. The intensity of signal corresponding to liquid in the polymer is compared to that of pure liquid in a reference sample, and correlations for T1 and T2 values versus signal intensity are used to deconvolve relaxation contrast, to yield the true liquid concentration. The technique was used to study the effect of degree of crosslinking of UHMWPE on the swelling kinetics and decalin transport within the polymer. A spin-echo imaging technique was used with a recycle delay approximately equal to the average spin-lattice relaxation time of the liquid, and an echo time approximately half the average spin-spin relaxation time. Under these conditions the relaxation contrast was significant, yet the mass uptake data derived from the concentration profiles obtained, using the method of analysis described, agreed well with gravimetric data. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331106
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  • 6
    Electronic Resource
    Electronic Resource
    Applications of Nuclear Magnetic Resonance Imaging in Particle Technology (1995)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 12 (1995), S. 59-67 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During the past decade, the application of Nuclear Magnetic Resonance (NMR) imaging techniques to problems of relevance to the process industries has been identified. In the context of particle technology, NMR imaging, in addition to the more routinely used techniques of Pulsed Gradient Spin Echo (PGSE) NMR and NMR spectroscopy, offer new methods of characterising pore structure, adsorption and diffusion processes within particles and packed beds of particles, as well as enabling time-resolved in-situ study of processes such as twophase flow, aggregation, polymerisation, crystallisation and phase separation phenomena. This paper reviews recent work in these areas, and also highlights the new insights NMR imaging can give us regarding the characterisation of porous materials, and the influence of the structure of the pore space on the transport processes occuring within a given porous solid.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19950120203
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  • 7
    Electronic Resource
    Electronic Resource
    Characterization of structural inhomogeneities in porous media (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 894-906 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recent studies have demonstrated that spatial heterogeneities in voidage and pore size, over lengthscales of 0.1-1 mm, significantly affect the transport of liquids within a given porous medium. Nuclear magnetic resonance imaging is used to probe the structure of porous catalyst support pellets, and four image analysis techniques characterize the degree and nature of heterogeneities observed in the spin-lattice relaxation-time images of six pellets taken from the same batch. Power-spectrum, cluster-size, and percolation analysis reveal significant differences in spatial correlations and topological characteristics of the six images. The fractal dimension of all the images, however, is the same suggesting that this quantity characterizes the intrinsic heterogeneities associated with the particular batch of porous pellets studied in this work. The results suggest that structural models of such pellets should account for these macroscopic variations in pellet structure, as characterized here.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410416
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  • 8
    Electronic Resource
    Electronic Resource
    NMR Imaging of nonaqueous-phase liquid dissolution in a porous medium (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1341-1349 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is demonstrated how NMR imaging can be used noninvasively to quantify the volume of nonaqueous phase liquid (NAPL) present in an otherwise water-saturated porous medium. Data were recorded during the operation of a pump and treat (PT) remediation scheme on a bed of water-saturated sand contained within a vertical column. The model contaminant used was n-hexanol, and three different aqueous flow rates were employed. These data were then critically compared with the predictions of three models currently used to describe the dissolution of NAPL during a PT scheme: the linear mass-transfer model, the pore-diffusion model, and the shrinking-core model. The pore-diffusion model gave best agreement with the experimental data. However, none of the models predicted the observed dependence of mass transfer on Darcy velocity.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420514
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  • 9
    Electronic Resource
    Electronic Resource
    Eine FT-Raman-Untersuchung der Templat-Gerüst-Wechselwirkungen in Molekularsieben auf AIPO4-BasisWir danken der Firma BNFL für die Bereitstellung des Raman-Spektrometers. (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 109 (1997), S. 919-921 
    Details
    ISSN: 0044-8249
    Keywords: Aluminiumphosphat ; Molekularsiebe ; Raman-Spektroskopie ; Templatsynthesen ; Wirt-Gast-Chemie ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19971090830
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  • 10
    Electronic Resource
    Electronic Resource
    An FT-Raman Study of the Template -Framework Interaction in AlPO4-Based Molecular Sieves (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 36 (1997), S. 876-878 
    Details
    ISSN: 0570-0833
    Keywords: aluminum phosphate ; host-guest chemistry ; molecular sieves ; Raman spectroscopy ; template synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.199708761
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