Structural analysis of cell membrane complex of a hair fibre by micro-beam X-ray diffraction

2005 ◽  
Vol 38 (2) ◽  
pp. 274-279 ◽  
Author(s):  
Noboru Ohta ◽  
Toshihiko Oka ◽  
Katsuaki Inoue ◽  
Naoto Yagi ◽  
Satoru Kato ◽  
...  

The cell membrane complex in the cuticle of a human hair fibre or a rat whisker is composed of three layers, that is, β, δ and β layers. The X-ray diffraction technique is a powerful tool to investigate the pathway of aqueous molecules and ions across the cuticle. Small-angle scattering experiments using a micro X-ray beam, which can be applied to a cuticle of 5 µm thickness, provide the structural information on the cell membrane complex without interference from other structures. Taking into account the variation of thickness in the δ and β layers, the overall features of the diffraction profile in a small-angle region can be explained satisfactorily. The method makes it possible to analyse the structure of β, δ and β layers without assuming an ambiguous background in the diffraction profile, and was used for the analysis of a human hair fibre and a rat whisker. In a rat whisker, the X-ray diffraction was stronger and the variation in the layer thickness smaller than in a human hair fibre. This may be due to the fact that the rat whisker had not been washed with soap or cosmetically treated, whereas the variation may depend on the lipids or the proteins that each species naturally has. It is proposed that the method represents convenient tool for quantitative analysis to estimate the thickness of δ and β layers in the cell membrane complex.

2005 ◽  
Vol 38 (5) ◽  
pp. 757-759 ◽  
Author(s):  
Guangrong Ning ◽  
Roberta L. Flemming

The Rietveld method of crystal structure refinement was an important breakthrough, allowing crystal structural information to be obtained from powder diffraction data. One remaining challenge is to collect Rietveld-quality data for polycrystalline mineralsin situ, using laboratory-based micro X-ray diffraction (µXRD) techniques. Here a new data collection method is presented, called `multiframes', which produces high-quality data, suitable for Rietveld refinement, using the Bruker D8 DISCOVER micro X-ray diffractometer. 91 frames of two-dimensional X-ray diffraction data were collected for powdered NIST SRM 660 LaB6standard material, using a general area-detector diffraction system (GADDS), at intervals of 0.8° 2θ. For each frame, only the central 1° 2θ was integrated and merged to produce a diffraction profile from 17 to 90° 2θ. Rietveld refinement of this data usingTOPAS2gave a unit-cell parameter (ao) and atomic position of boron (x) for LaB6of 4.1549 (1) Å and 0.1991 (9), respectively (Rwp= 4.26,RBragg= 3.21). The corresponding La—B bond length was calculated to be 3.0522 Å. These parameters are in good agreement with the literature values for LaB6. These encouraging results suggest that Rietveld-quality micro X-ray diffraction data can be collected from the Bruker D8 DISCOVER diffractometer, provided that the GADDS detector is stepped in small increments, for each frame only the central 1° 2θ is integrated at constant arc length, and counting time is sufficient to yield adequate intensity (∼10 000 counts).


Author(s):  
L. Rudy ◽  
R. Sneath ◽  
M. Song

The basic morphology of the non-keratinous regions of human hair fibers was studied using both conventional and high voltage electron microscopy. The non-keratinous regions of hair include the endocuticle, the cell membrane complex, and the nuclear remnants of the cortex. By characterizing these regions more clearly, the mechanisms by which external influences affect the hair can be understood. The nuclear remnants are surrounded by a cell membrane complex. Since thin sectioning often causes artifacts in these fragile structures, a three-dimensional reconstruction using serial, semi-thick sections was completed to reveal their morphological nature.Human hair fibers collected from a female subject, had not been treated with any chemically active processes. One centimeter samples were collected near the scalp region of the back of the head. The fibers were embedded in Epon-812. Serial, semi-thick sections, 0.25u thick, were sectioned and collected on copper slot, formvar-coated grids. Post-staining was completed with uranyl acetate and lead citrate. Sections were examined in an AEl EM7 Mk 1.2MV HVEM at an accelerating voltage of 1.0 MV.


2003 ◽  
Vol 43 (supplement) ◽  
pp. S171
Author(s):  
N. Ohta ◽  
T. Oka ◽  
K. Inoue ◽  
N. Yagi ◽  
S. Kato ◽  
...  

2004 ◽  
Vol 44 (supplement) ◽  
pp. S79
Author(s):  
N. Ohta ◽  
T. Oka ◽  
K. Inoue ◽  
N. Yagi ◽  
S. Kato ◽  
...  

Author(s):  
S. W. Hui ◽  
T. P. Stewart

Direct electron microscopic study of biological molecules has been hampered by such factors as radiation damage, lack of contrast and vacuum drying. In certain cases, however, the difficulties may be overcome by using redundent structural information from repeating units and by various specimen preservation methods. With bilayers of phospholipids in which both the solid and fluid phases co-exist, the ordering of the hydrocarbon chains may be utilized to form diffraction contrast images. Domains of different molecular packings may be recgnizable by placing properly chosen filters in the diffraction plane. These domains would correspond to those observed by freeze fracture, if certain distinctive undulating patterns are associated with certain molecular packing, as suggested by X-ray diffraction studies. By using an environmental stage, we were able to directly observe these domains in bilayers of mixed phospholipids at various temperatures at which their phases change from misible to inmissible states.


2020 ◽  
Vol 38 (4A) ◽  
pp. 491-500
Author(s):  
Abeer F. Al-Attar ◽  
Saad B. H. Farid ◽  
Fadhil A. Hashim

In this work, Yttria (Y2O3) was successfully doped into tetragonal 3mol% yttria stabilized Zirconia (3YSZ) by high energy-mechanical milling to synthesize 8mol% yttria stabilized Zirconia (8YSZ) used as an electrolyte for high temperature solid oxide fuel cells (HT-SOFC). This work aims to evaluate the densification and ionic conductivity of the sintered electrolytes at 1650°C. The bulk density was measured according to ASTM C373-17. The powder morphology and the microstructure of the sintered electrolytes were analyzed via Field Emission Scanning Electron Microscopy (FESEM). The chemical analysis was obtained with Energy-dispersive X-ray spectroscopy (EDS). Also, X-ray diffraction (XRD) was used to obtain structural information of the starting materials and the sintered electrolytes. The ionic conductivity was obtained through electrochemical impedance spectroscopy (EIS) in the air as a function of temperatures at a frequency range of 100(mHz)-100(kHz). It is found that the 3YSZ has a higher density than the 8YSZ. The impedance analysis showed that the ionic conductivity of the prepared 8YSZ at 800°C is0.906 (S.cm) and it was 0.214(S.cm) of the 3YSZ. Besides, 8YSZ has a lower activation energy 0.774(eV) than that of the 3YSZ 0.901(eV). Thus, the prepared 8YSZ can be nominated as an electrolyte for the HT-SOFC.


2012 ◽  
Vol 54 (10) ◽  
pp. 2073-2082 ◽  
Author(s):  
A. K. Samusev ◽  
I. S. Sinev ◽  
K. B. Samusev ◽  
M. V. Rybin ◽  
A. A. Mistonov ◽  
...  
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