Bettina Pfleiderer

Bio: Bettina Pfleiderer is an academic researcher from University of Tübingen. The author has contributed to research in topics: Silica gel & Magic angle spinning. The author has an hindex of 9, co-authored 10 publications receiving 306 citations.

A new approach to the silica gel surface : characterization of different surface regions by 29Si magic angle spinning NMR relaxation parameters and consequences for quantification of silica gels by NMR: characterization of different surface regions by silicon-29 magic angle spinning NMR relaxation parameters and consequences for quantification of silica gels by NMR

Abstract: Native and some monofunctionally derivatized silica gels have been investigated by 29Si CP MAS NMR spectroscopy with pulse and with cross-polarization (CP) excitation. Contact time variation experiments for some native materials yield results for the siloxane (Q4)g roups which cannot be described with a single set of THsi and TlpHv alues. Quantitative analyses of such silicas with CP excitation require CP curves as standards. For these samples Tlsi values measured with pulse excitation differ from those obtained by CP excitation. TlpHv alues depend on the contact time, selected for the experiment. Moreover, multiexponential Tlsi analyses for Q3 and Q4 reveal that the longitudinal relaxation process of native silica gels generally can be separated into at least three different processes, each with its characteristic average value for Tlsi. Explanations for CP behavior and Tlsi inhomogeneities are offered in terms of different forms of coexistence in silica gels of relatively mobile amorphous regions. Implications of these results for quantification of surface groups of silicas with cross-polarization MAS NMR are discussed.

Investigation of the diffusion process in cross-linked polystyrenes by means of NMR imaging and solid-state NMR spectroscopy

Abstract: The diffusion process of dioxane in cross-linked polystyrenes can be monitored by combined NMR imaging and solid-state NMR techniques. NMR imaging data reveal a strong dependence of the diffusion behavior upon the cross-link density: in the case of lowest cross-linking (1%), a case II diffusion process takes place, whereas in the case of highest cross-linking (5%), Fickian diffusion occurs. The 2.5% cross-linked polystyrene shows intermediate behavior. Solid-state NMR relaxation parameters indicate great differences between the unswollen and the swollen state

NMR imaging of materials

Abstract: NMR imaging methods are provided for determining the spatial petrophysical properties of materials. These methods employ the generation of separate Mo, T1 and T2 images from which various petrophysical characteristics may be obtained, such as free fluid index, porosity, pore sizes and distributions, capillary pressure, permeability, formation factor and clay content.

Matrices with memories and uses thereof

Abstract: Combinations, called matrices with memories, of matrix materials that are encoded with an optically readable code are provided. The matrix materials are those that are used in as supports in solid phase chemical and biochemical syntheses, immunoassays and hybridization reactions. The matrix materials may additionally include fluophors or other luminescent moieties to produce luminescing matrices with memories. The memories include electronic and optical storage media and also include optical memories, such as bar codes and other machine-readable codes. By virtue of this combination, molecules and biological particles, such as phage and viral particles and cells, that are in proximity or in physical contact with the matrix combination can be labeled by programming the memory with identifying information and can be identified by retrieving the stored information. Combinations of matrix materials, memories, and linked molecules and biological materials are also provided. The combinations have a multiplicity of applications, including combinatorial chemistry, isolation and purification of target macromolecules, capture and detection of macromolecules for analytical purposes, selective removal of contaminants, enzymatic catalysis, cell sorting, drug delivery, chemical modification and other uses. Methods for tagging molecules, biological particles and matrix support materials, immunoassays, receptor binding assays, scintillation proximity assays, non-radioactive proximity assays, and other methods are also provided.