Diffraction small-angle X-ray

Cationic quaternary ammonium compounds such as distearyldimethylammonium-chloride (DSDMAC) used as a softener and as an antistatic, form hydrated particles in a dispersed phase having a similar structure to that of the multilayered liposomes or vesicles of phospholipids 77,79). This liposome-like structure could be made visible by electron microscopy using the freeze-fracture replica technique as shown by Okumura et al. 79). The concentric circles observed should be bimolecular lamellar layers with the sandwiched parts being the entrapped water. In addition, the longest spacings of the small angle X-ray diffraction pattern can be attributed to the inter-lamellar distances. These liposome structures are formed by the hydrated detergent not only in the gel state but also at relatively low concentrations. 

Figure 8.8 Space-filling model based on small-angle X-ray diffraction measures, showing how two hemidiscotic molecules of 8 can give rise to a disk-like shape. (Adapted from Ref [11].)...

T.J. Wess, M. Drakopoulos, A. Snigirev, J. Wounters, O. Paris, P. Fratzl, M. Collins, J. Hiller, K. Nielsen, The Use of Small Angle X Ray Diffraction Studies for the Analysis of Structural Features in Archaeological Samples, Archaeometry, 43, 117 129 (2001). 

Wess, T. J., Drakopoulos, M., Snigirev, A., et al. (2001). The use of small-angle X-ray diffraction studies for the analysis of structural features in archaeological samples. Archaeometry 43 117-129. 

Figure 4.1-6 Small-angle X-ray diffraction data from [cetyltrimethylammonium]2[ZnCl4] at (a) room temperature (solid), (b) 90 °C (Sc phase) and (c) 200 °C (S/ phase). Reproduced from reference 25 with permission.

Figure 4.1-7 Small-angle X-ray diffraction data from [C,6MIM][OTf] at (a) 50 °C,...

Small-angle X-ray diffraction was performed on three selected fractions (Mw = 13000 45800 91500) within concentrations of 0.5 and 4%. Rigid rodlike geometry of the molecules is indicated in the angular dependence of the scattering intensities. 

Over the last years the utilisation of supramolecular arrays of surfactant molecules as structure-directing templates [1] has been applied to the synthesis of numerous mesostructured aluminophosphates [2-11]. In most cases the preparations were carried out in aqueous systems under hydrothermal conditions, but tetraethylene glycol and/or unbranched primary alcohols were also used [2,4]. Several discussions have been made on the reaction mechanisms that are involved in the syntheses of mesostructured materials [1,12-15] and recently a number of in-situ investigations on the formation processes of mesostructured silica phases in aqueous media have been reported these studies employed small angle X-ray diffraction [16-19] as well as 2H, 13C, 29Si, and 8lBr NMR spectroscopy and polarised light optical microscopy [17]. 

A specific feature of all polymeric smectics, independently of the mesophase type, is that the regions of LC ordering are limited, while low-molecular liquid crystals display macroscopic ordering. This follows from the analysis of absolute intensities of small angle X-ray diffraction performed recently108-l09) (see polymers C. 1.1-C. 1.5 Table 4). 

Fig. 21 Small-angle X-ray diffraction pattern of an aligned sample of 134b at 110 °C. Reproduced by permission of The Royal Society of Chemistry from [127]...

Cornwell, P.A., et al. 1996. Modes of action of terpene penetration enhancers in human skin differential scanning calorimetry, small-angle x-ray diffraction and enhancer uptake studies. Int J Pharm 127 9. 

Fig. 4 Elongation of the R3 phosphate ester chain of the cationic PC results in nonlamellar phase formation. Small-angle X-ray diffraction patterns recorded at 20° C show (a) lamellar La (b) cubic Pn3m (c) inverted hexagonal Hn phases formed by dioleoyl cationic PCs with ethyl, hexyl and octadecyl R3 chains, respectively, diCl8 1 -EPC [19], diC18 l-C6PC [20] and diC18 l-C18PC [21]...

Fig. 23 (a) Small-angle X-ray diffraction profile of EDOPC lipoplexes at 4 1 lipid/DNA weight ratio (arrow points to the peak originating from DNA-DNA in-plane correlation) inset, thin-section electron microscopy image of EDOPC lipoplexes (reproduced with permission from [81] copyright (2007) Elsevier), (b) Electron density profiles of the lipid bilayer in presence and in absence of DNA [16] (copyright (2000) Biophysical Society)... 

J. A. Bouwstra, G. S. Gooris, M. A. Salomons-de Vries, and W. Bras, The influence of N-alkyl-azones on the ordering of the lamellae in human stratum comeum, as determined by small angle x-ray diffraction, Int. J. Pharm. 79 141-148 (1992). 

Figure 16.1 (a) Transmission electron micrograph and (b) small angle X-ray diffraction pattern of a... 

Small-angle X-ray diffraction was used to identify the time-averaged location of amiodarone in a synthetic lipid bilayer. The drug was located about 6 A from the center of the lipid bilayer (Figure 4.13) [125, 126]. A dielectric constant of k = 2, which is similar to that of the bilayer hydrocarbon region, was used to calculate the minimum energy conformation of amiodarone bound to the membrane. The studies were performed below the thermal phase transition and at relatively low hydration of lipid. The calculated conformation differed from that of the crystal structure of amiodarone. Even though the specific steric effects of the lipid acyl chains on the confor-... 

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