Small angle diffraction studies

Bouwstra, J.A., et al. 1994. The lipid and protein structure of mouse stratum corneum A wide and small angle diffraction study. Biochim Biophys Acta 1212 183. 

Bouwstra, J. A., Gooris, G. S., Van der Spek, J. A., Lavrijsen, S. and Bras, W. (1994). The lipid and protein stmcture of mouse stratum comeum A wide- and small-angle diffraction study. Biochim. Biophys. Acta /2/2 183. 

Much of the matter dealing with the small-angle X-ray diffraction was accomplished in collaboration with Dr. O. E. A. Bolduan and Mrs. Mildred Marks Siegel, with biological and chemical cooperation from Drs. C. H. Blake and T. P. Salo, respectively. Dr. E. Faur -Fremiet of Paris contributed the shark elastoidin and skate ovokeratin samples, concerning which the results of small-angle diffraction study appear here for the first time. 

These solution studies should not be confused with the small angle diffraction studies of orientated multilayer specimens such as the myeUn sheaths of nerves, the outer segments of retinal rods, layered purple membranes from Halobacterium halobium and those that are made artificially by flattening vesicles by centrifugation or by drying. Here a different methodology based on diffraction is employed, which is discussed elsewhere [256-258]. 

Holland, H.E., et al. 1995. Interactions between liposomes and human stratum corneum in vitro Freeze fracture electron microscopical visualization and small angle diffraction scattering studies. Br J Dermatol 132 853. 

The Biology Department beam line includes a station for protein crystallography (with Supper oscillation camera and FAST TV diffractometer) and a station for small angle diffraction (with a three-circle goniostat and MWPC electronic area detector). The latter station may be available for optimised anomalous dispersion crystallographic studies. The optical design for each consists of a bent pre-mirror, double crystal monochromator and bent post-mirror the mirrors have rhodium coatings (Wise and Schoenborn 1982). 

Small-angle diffraction disclosed a faint collagen-type diffraction in beef ligament (18), such as would result from a small amount of collagen impurity included with the elastin. Elastin has also been studied elec-... 

X-Ray diffraction or electron optical evidence of the changes in shape of individual fibrils caused by swelling is meager, but Nutting and Borasky (164) reported that aczd-swollen fibrils become thickened and exhibit axial periods shortened to 540 A. Small-angle diffraction, on the other hand, shows in neutral aqueous environments (Section IV, 3) an increase of fibrillar period from 640 to about 670 A., though the effects of salt solutions have not been studied. 

So far in our consideration of small-angle diffraction behaviour we have not considered the effective of diffuse interfacial layers. Porod showed that the tail i.e. the asymptotic behaviour at high angles) of a scattering curve for an ideal two-phase system with sharp boundaries between the phases should have an intensity proportional to s " for a system studied with point collimation and proportional to s when studied with infinite slit collimation. 

Powder diffraction studies with neutrons are perfonned both at nuclear reactors and at spallation sources. In both cases a cylindrical sample is observed by multiple detectors or, in some cases, by a curved, position-sensitive detector. In a powder diffractometer at a reactor, collimators and detectors at many different 20 angles are scaimed over small angular ranges to fill in the pattern. At a spallation source, pulses of neutrons of different wavelengdis strike the sample at different times and detectors at different angles see the entire powder pattern, also at different times. These slightly displaced patterns are then time focused , either by electronic hardware or by software in the subsequent data analysis. 

Section 2 of this chapter describes the characterization of carbonaceous materials by powder X-ray diffraction, small-angle-X-ray scattering (SAXS), measurements of surface area, and by the carbon-hydrogen-nitrogen (CHN) test, a chemical analysis of composition. In this section, we also describe the electrochemical methods used to study carbonaceous materials. 

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). 

There are many ways to characterize the structure and properties of carbonaceous materials. Among these methods, powder X-ray diffraction, small angle X-ray scattering, the BET surface area measurement, and the CHN test are most useful and are described briefly here. To study lithium insertion in carbonaceous materials, the electrochemical lithium/carbon coin cell is the most convenient test vehicle. 

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