NMR Investigations of Self-Diffusion and Shear Thinning for Semidilute Polymer Solutions near the Demixing Transition

Manz, B.; Callaghan, P. T.

doi:10.1021/ma961851n

Cited by 19 publications

(24 citation statements)

References 68 publications

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“…For uncorrelated, Brownian motion of many molecules, the amplitude of the echo signal decreases due to molecular self-diffusion. By measuring the NMR signal with increasing gradient strength, flow velocities as well as self-diffusion and dispersion coefficients can be determined (Callaghan, 1991;Callaghan & Xia, 1991;Manz & Callaghan, 1997;Manz et al, 1998Manz et al, , 1999aManz et al, , b, 2003Seymour et al, 1999;Manz, 2004).…”

Section: The Mri Methodsmentioning

confidence: 99%

Advanced imaging techniques for assessment of structure, composition and function in biofilm systems

Neu

Manz

Volke

et al. 2010

FEMS Microbiology Ecology

204

138

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Scientific imaging represents an important and accepted research tool for the analysis and understanding of complex natural systems. Apart from traditional microscopic techniques such as light and electron microscopy, new advanced techniques have been established including laser scanning microscopy (LSM), magnetic resonance imaging (MRI) and scanning transmission X-ray microscopy (STXM). These new techniques allow in situ analysis of the structure, composition, processes and dynamics of microbial communities. The three techniques open up quantitative analytical imaging possibilities that were, until a few years ago, impossible. The microscopic techniques represent powerful tools for examination of mixed environmental microbial communities usually encountered in the form of aggregates and films. As a consequence, LSM, MRI and STXM are being used in order to study complex microbial biofilm systems. This mini review provides a short outline of the more recent applications with the intention to stimulate new research and imaging approaches in microbiology.

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Section: The Mri Methodsmentioning

confidence: 99%

Advanced imaging techniques for assessment of structure, composition and function in biofilm systems

Neu

Manz

Volke

et al. 2010

FEMS Microbiology Ecology

204

138

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“…The phase shift arises from correlated molecular displacements (e.g., flow) over the well-defined interval D. For uncorrelated, Brownian motion the amplitude of the echo signal decreases due to molecular self-diffusion. By measuring the NMR signal with increasing gradient strength g, flow velocities as well as self-diffusion coefficients can be determined (Callaghan, 1991;Callaghan and Xia, 1991;Manz and Callaghan, 1997).…”

Section: Magnetic Resonance Imagingmentioning

confidence: 99%

Measuring local flow velocities and biofilm structure in biofilm systems with Magnetic Resonance Imaging (MRI)

Manz

Volke

Goll

et al. 2003

Biotech & Bioengineering

117

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Abstract:The characterization of substrate transport in the bulk phase and in the biofilm matrix is one of the problems which has to be solved for the verification of biofilm models. Additionally, the surface structure of biofilms has to be described with appropriate parameters. Magnetic resonance imaging (MRI) is one of the promising methods for the investigation of transport phenomena and structure in biofilm systems. The MRI technique allows the noninvasive determination of flow velocities and biofilm structures with a high resolution on the sub-millimeter scale. The presented investigations were carried out for defined heterotrophic biofilms which were cultivated in a tube reactor at a Reynolds number of 2000 and 8000 and a substrate load of 6 and 4 g /m 2 d glucose. Magnetic resonance imaging provides both structure data of the biofilm surface and flow velocities in the bulk phase and at the bulk/biofilm interface. It is shown that the surface roughness of the biofilms can be determined in one experiment for the complete cross section of the test tubes both under flow and stagnant conditions. Furthermore, the local shear stress was calculated from the measured velocity profiles. In the investigated biofilm systems the local shear stress at the biofilm surface was up to 3 times higher compared to the mean wall shear stress calculated on the base of the mean flow velocity.

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“…As demonstrated here, substantial information about the putative role of xylem lipids in withstanding drying and facilitating subsequent rehydration could be obtained by light and electron microscopy and in particular by the numerous complementary variants offered by NMR spectroscopy and imaging (Kuchenbrod et al ., 1995, 1996, 1998; Volke & Pampel, 1995; Bentrup, 1996; Manz & Callaghan, 1997; Manz et al ., 1997, 1999; Meininger et al ., 1997; Volke et al ., 1997; Pampel et al ., 1998; Rokitta et al ., 1999; Seymour et al ., 1999; Wagner et al ., 2000; Wistuba et al ., 2000; Peuke et al ., 2001; Zimmermann et al ., 2001). In contrast to the microscopy techniques, the noninvasive NMR methods allowed measurements on lipid composition, mobility and distribution on the same branch both in the presence and absence of water.…”

Section: Introductionmentioning

confidence: 99%

The impact of lipid distribution, composition and mobility on xylem water refilling of the resurrection plantMyrothamnus flabellifolia

et al. 2003

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Summary• Lipids play a crucial role in the maintenance of the structural and functional integrity of the water-conducting elements and cells of the resurrection plant Myrothamnus flabellifolia during complete dehydration.• Lipid composition, mobility and distribution within the internodal and nodal xylem regions (including short shoots and leaves) were investigated in the presence and absence of water by using various nuclear magnetic resonance (NMR) spectroscopy and imaging techniques differing greatly in the level of spatial resolution and acquisition of lipid parameters.• Significant findings include: a discontinuity in the branch xylem between an inner zone where no water moves and an outer zone where the water moves; the blocking of water movement in the inner zone by lipids that are not dispersed by water, and the facilitation of water advance in the xylem elements and pits of the outer zone by water-dispersed lipids; the relative impermeability of leaf trace xylem to the rehydrating water and, hence, the relative hydraulic isolation of the leaves.• These results elucidated part of the strategy used by the resurrection plant to cope with extreme drought and to minimize transpirational water loss upon hydration.

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NMR Investigations of Self-Diffusion and Shear Thinning for Semidilute Polymer Solutions near the Demixing Transition

Cited by 19 publications

References 68 publications

Advanced imaging techniques for assessment of structure, composition and function in biofilm systems

Advanced imaging techniques for assessment of structure, composition and function in biofilm systems

Measuring local flow velocities and biofilm structure in biofilm systems with Magnetic Resonance Imaging (MRI)

The impact of lipid distribution, composition and mobility on xylem water refilling of the resurrection plantMyrothamnus flabellifolia

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