Effect of Added Salts or Polyols on the Cloud Point and the Liquid-Crystalline Structures of Polyoxyethylene-Modified Silicone
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Cloud point
Small-angle X-ray scattering
Small-angle X-ray scattering
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Summary Introduction It has been proposed that exogenous pulmonary surfactant can be used as a drug delivery system for immunosuppressive agents to the alveolar compartment of the lung while reducing the risk of systemic toxicity. Before using this combination, however, alterations in activity of both substances should be examined. Therefore, this study investigated whether the activity of a natural derived surfactant preparation is changed after it is mixed with cyclosporine A (CsA) or rapamycin (RPM). Methods A surfactant suspension was mixed with CsA or RPM and minimal surface tension of these mixtures was measured in vitro . Surfactant activity was evaluated in vivo by its capacity to restore gas exchange in an established model of surfactant deficiency in rats. CsA–surfactant, RPM–surfactant or surfactant alone was instilled intratracheally and blood gases were measured under standardized ventilatory conditions. Results Minimal surface tension of surfactant–CsA was comparable with that of surfactant alone, whereas minimal surface tension of the surfactant–RPM mixture was increased. In vivo partial arterial oxygen pressure levels increased immediately to prelavage values after instillation of CsA–surfactant, RPM–surfactant and surfactant only and were comparable during the entire study period. Conclusion The activity of a naturally derived surfactant was affected when mixed with RPM but not when mixed with CsA at the used concentrations.
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Abstract Small angle X‐ray scattering (SAXS) is a powerful method for investigating macromolecular structure in solution. SAXS data provide information about the size and shape of a molecule with a resolution of ∼2 to 3 nm. SAXS is particularly useful for the investigation of nucleic acids, which scatter X‐rays strongly due to the electron‐rich phosphate backbone. Therefore, SAXS has become an increasingly popular method for modeling nucleic acid structures, an endeavor made tractable by the highly regular helical nature of nucleic acid secondary structures. Recently, SAXS was used in combination with NMR to filter and refine all‐atom models of a U2/U6 small nuclear RNA complex. In this unit, general protocols for sample preparation, data acquisition, and data analysis and processing are given. Additionally, examples of correctly and incorrectly processed SAXS data and expected results are przovided. Curr. Protoc. Nucleic Acid Chem . 51:7.18.1‐7.18.18. © 2012 by John Wiley & Sons, Inc.
Small-angle X-ray scattering
Nucleic acid structure
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Abstract Amphiphilic star‐shaped oligo(ethylene glycol)s with a hydrophobic bile acid core and varying number of hydrophilic arms have been made. Their thermal behavior in aqueous solutions depends on the number rather than the length of the arms. The two‐armed lithocholate derivative showed the strongest tendency for association and exhibited the lowest cloud point (79 °C) of the oligomers made, as well as another phase separation at a lower temperature (31 °C). The “double thermosensitivity” arising both from the salt‐dependent LCST of the oligo(ethylene glycol) segments and the temperature‐responsive self‐assembly of amphiphilic bile acid derivative provides an interesting path in the design of bile acid‐based smart materials. magnified image
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Acrylic acid
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Small-angle X-ray scattering
Divinylbenzene
Morphology
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Close spacing bio-surfactant tertiary composite flooding pilot test indicated, compared to tertiary composite surfactant system without adding bio-surfactant, usage of sulphonate surfactant and cost of injected chemical decreased respectively by 1/2 and 30% for bio-surfactant tertiary composite system, which is formed by rhamnoilpid bio-surfactant and sulphonate surfactant. The ultra-low interface tension value between flooding system and crude oil reached 10-3mN/m, and recovery factor for central well site and that for overall area increased by 23. 24% and 16. 34% , respectively.
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This chapter focuses on methodological developments aiming to interpret small-angle X-ray scattering (SAXS) data for topological structure characterization of large biomolecular assemblies. It also focuses on developments on modeling large protein complexes that can adopt a single conformation or exist in a mixture of multiple conformations. In particular, conformation generation from large-scale computations provides a solid theoretical foundation for SAXS data interpretation. In the midst of broadened SAXS applications, the emerging potential of a SAXS analysis for visualizing the protein topology of biomolecular complexes is apparent, especially when already known structures of individual components are productively used in theoretical and computational studies designed for SAXS data analysis. In fact, it is counter-intuitive that the sample preparation needed for a SAXS measurement could be more stringent when compared to crystallographic requirements given that crystallization itself is a highly efficient purification process.
Small-angle X-ray scattering
Characterization
Small-Angle Scattering
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Small-angle X-ray scattering
Nanoporous
Small-Angle Scattering
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