scholarly journals THE ROLE OF WATER IN THE STRUCTURE OF PERIPHERAL NERVE MYELIN

1957 ◽  
Vol 3 (1) ◽  
pp. 95-102 ◽  
Author(s):  
J. B. Finean
Keyword(s):  
Water Distribution ◽  
Water Evaporation ◽  
X Ray Diffraction ◽  
Nerve Fibres ◽  
Diffraction Patterns ◽  
Protein Components ◽  
Five Phases ◽  
Kinetics Of ◽  
Frog Sciatic Nerve

In the study of the drying kinetics of nerve fibres, at least five "phases" of water evaporation can be distinguished. A consideration of the accompanying changes in low-angle x-ray diffraction patterns permits a tentative identification of the "phases" and a quantitative interpretation of the data in terms of the water distribution in nerve fibres. These results suggest that the myelin sheath of frog sciatic nerve contains 40 to 50 per cent water, and it is suggested further that the greater part of this water is "organised" in relation to the hydrophilic groups of the lipide and protein components.

scholarly journals The role of REE3+ in the crystallization of lanthanites

2014 ◽  
Vol 78 (6) ◽  
pp. 1373-1380 ◽  
Author(s):  
Juan Diego Rodriguez-Blanco ◽  
Beatriz Vallina ◽  
Jesus A. Blanco ◽  
Liane G. Benning
Keyword(s):  
Structural Characteristics ◽  
X Ray Diffraction ◽  
Ionic Potential ◽  
Cell Dimensions ◽  
Ion Size ◽  
Unit Cell Dimensions ◽  
Kinetics Of ◽  
Carbonate Precursor ◽  
High Resolution Microscopy

The formation of crystalline rare earth element (REE) (e.g. La, Ce, Pr, Nd) carbonates from aqueous solutions was examined at ambient temperature using UV-Vis spectrophotometry, combined with X-ray diffraction, high-resolution microscopy and infrared spectroscopy. In all experiments REE-lanthanites (REE2(CO3)3·8H2O) formed via a highly hydrated, nanoparticulate and poorlyordered REE-carbonate precursor. The lifetime of this precursor as well as the kinetics of crystallization of the various REE-lanthanites were dependent on the specific REE3+ ion involved in the reaction. The induction time and the time needed to fully form the crystalline REE-lanthanite end products increase linearly with the ionic potential. The authors show here that the differences in ion size and ionic potential as well as differences in dehydration energy of the REE3+ ions control the lifetime of the poorly ordered precursor and thus also the crystallization kinetics of the REE-lanthanites; furthermore, they also affect the structural characteristics (e.g. unit-cell dimensions and idiomorphism) of the final crystalline lanthanites.

THE ROLE OF LIPOIDS IN THE X-RAY DIFFRACTION PATTERNS OF NERVE

Science ◽  
1935 ◽  
Vol 82 (2115) ◽  
pp. 44-45 ◽  
Author(s):  
F. O. Schmitt ◽  
R. S. Bear ◽  
G. L. Clark
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

Study on the Effects of Type I Collagen Combined with Noncollagenous Proteins on Hydroxyapatite Formation in vitro using SPM and GIXD

2009 ◽  
Vol 1238 ◽  
Author(s):  
Xiaolan Ba ◽  
Elaine DiMasi ◽  
Miriam H Rafailovich
Keyword(s):  
Type I Collagen ◽  
Early Stage ◽  
Cooperative Interaction ◽  
Type I ◽  
X Ray Diffraction ◽  
Noncollagenous Proteins ◽  
Force Microscopy ◽  
Kinetics Of

AbstractThe effects of the components of extracellular matrix on the bone formation and the kinetics of crystal growth of calcium phosphate have remained unknown. In this paper, we reported a method to investigate the role of Type I collagen and the interactions with other ECM proteins such as fibronectin and elastin during biomimic mineralization process in vitro. The early stage of mineralization was characterized by scanning probe microscopy (SPM) and shear modulation force microscopy (SMFM). The late stage of mineralization was investigated by synchrotron grazing incident x-ray diffraction (GIXD). The results demonstrate the cooperative interaction between type I collagen and noncollagenous proteins such as fibronectin or elastin could be essential for the biomineralization.

scholarly journals Phase Identification by Rotation Electron Diffraction from Multiphasic Samples

2014 ◽  
Vol 70 (a1) ◽  
pp. C1080-C1080
Author(s):  
Yifeng Yun ◽  
Wei Wan ◽  
Faiz Rabbani ◽  
Jie Su ◽  
Sven Hovmöller ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Three Dimensional ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Groups ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Five Phases ◽  
Oxide Sample

Electron Crystallography is an important technique for studying micro- and nano-sized crystals[1]. Crystals considered as powder by X-ray diffraction behave as single crystals by electron diffraction. Recently we developed a new method, Rotation Electron Diffraction (RED) for three-dimensional diffraction data collection by combining electron beam tilt with goniometer tilt on a transmission electron microscope (TEM)[2]. Here we apply the RED method on an unknown oxide sample in a Ni-Se-Cl-O system, which may show special physical properties, for example magnetic properties. The crystals in the sample were less than a few micrometers in sizes. Powder X-ray diffraction patterns of the sample could not be indexed by existing known phases. The sample was thus studied by TEM. Five 3D RED datasets were collected from five crystals with different morphologies using the software package RED. The data processing was also performed using the software RED-processing. The unit cell and space groups of all the five phases were obtained using RED and the structures of four of five phases were solved. Nearly all peaks in the powder X-ray diffraction pattern could be indexed using these five phases. To conclude, five phases from a powder sample have been identified using RED. RED is a powerful method for phase identification of multiphasic samples with nano-sized crystals.

A kinetic study of the phase transformations in Al2O3 and Na2O · 6Al2O3 by a combined use of 27Al MAS NMR spectroscopy and x-ray diffraction: Importance of nucleation

1991 ◽  
Vol 6 (12) ◽  
pp. 2701-2705 ◽  
Author(s):  
S. Prabakar ◽  
K.J. Rao ◽  
C.N.R. Rao
Keyword(s):  
Nmr Spectroscopy ◽  
Phase Transformations ◽  
Mas Nmr ◽  
X Ray Diffraction ◽  
X Ray ◽  
Combined Use ◽  
27Al Mas Nmr ◽  
First Time ◽  
Kinetics Of

Phase transformations of Al2O3 and Na2O · 6Al2O3 prepared by the gel route have been investigated for the first time by 27Al MAS NMR spectroscopy in combination with x-ray diffraction. Of particular interest in the study is the kinetics of the γ → α and γ → β transformations, respectively, in these two systems. Analysis of the kinetic data shows the important role of nucleation in both these transformations.

Franconite, NaNb2O5(OH)·3H2O: structure determination and the role of H bonding, with comments on the crystal chemistry of franconite-related minerals

2014 ◽  
Vol 78 (3) ◽  
pp. 591-607 ◽  
Author(s):  
M. M. M. Haring ◽  
A. M. McDonald
Keyword(s):  
Crystal Structure ◽  
Ion Exchange ◽  
Molecular Sieves ◽  
Chemical Analyses ◽  
X Ray Diffraction ◽  
Synthetic Compounds ◽  
X Ray ◽  
Distorted Octahedral ◽  
Diffraction Patterns

AbstractThe crystal structure of franconite, NaNb2O5(OH)·3H2O, has been characterized by single-crystal X-ray diffraction using material from Mont Saint-Hilaire, Québec, Canada. Results givea= 10.119(2),b= 6.436(1),c= 12.682(2) Å and β = 99.91(3)° and confirm the correct space group asP21/c. The crystal structure, refined toR= 4.63% andwR2=11.95%, contains oneNasite, two distorted octahedralNbsites and nineOsites. It consists of clusters of four edge-sharing Nb(O,OH)6octahedra, linked through shared corners to adjacent clusters, forming layers of Nb(O,OH)6octahedra. These alternate along [100] with layers composed of NaO(H2O)4polyhedra, the two being linked together by well defined H bonding. The predominance of H bonding, essential to the mineral, results in a perfect {100} cleavage. Chemical analyses (n= 7) of four crystals give the empirical formula (Na0.73Ca0.13☐0.14)∑=1.00(Nb1.96Ti0.02Si0.02Al0.01)∑=2.01O5(OH)·3H2O (based on nine oxygens) or ideally NaNb2O5(OH)·3H2O. Franconite is crystallo-chemically related to SOMS [Sandia Octahedral Molecular Sieves; Na2Nb2−xMxO6−x(OH)x·H2O with M = Ti, Zr, Hf], a group of synthetic compounds with strong ion-exchange capabilities. Both hochelagaite (CaNb4O11·nH2O) and ternovite (MgNb4O11·nH2O) have X-ray powder diffraction patterns and cation ratios similar to those of franconite indicating that these minerals probably have similar structures.

Role of Cement Type on Carbonation Attack

2002 ◽  
Vol 17 (7) ◽  
pp. 1834-1842 ◽  
Author(s):  
S. Goñi ◽  
M. T. Gaztañaga ◽  
A. Guerrero
Keyword(s):  
Calcium Aluminate ◽  
Calcium Aluminate Cement ◽  
Alkali Content ◽  
X Ray Diffraction ◽  
Before And After ◽  
Natural Carbonation ◽  
Kinetics Of ◽  
Aluminate Cement ◽  
Hydrated Calcium

The carbonation of two hydrated ordinary portland cements of alkali content 1.03% or 0.43% Na2O equivalent and hydrated calcium aluminate cement (0.1% Na2O equivalent) was studied in a semi-dynamic atmosphere of 100% CO2, and 65% relative humidity at 20 ± 1 °C, for a period of 100 days. The changes of the microstructure before and during the carbonation were characterized by x-ray diffraction, mercury intrusion porosimetry, and scanning electron microscopy. The kinetics of the process was evaluated from the total CaCO3 content by means of thermogravimetric analysis. The changes of the mechanical flexural strength were also studied. The pore solution was collected and analyzed before and after different periods of time. The results were compared with those obtained under natural carbonation conditions. The results showed that the alkali content of cement does not influence the kinetics of the process when the carbonation is accelerated. In the case of natural carbonation, an induction period is produced in the ordinary portland cement of low alkali content and calcium aluminate cement. The carbonation rate of calcium aluminate cement is the slowest for accelerated and natural carbonation.

SYNTHESIS FOR NANOFLOWER AND ROD OF ZnO BY A SURFACTANT FREE AND LOW TEMPERATURE METHOD

2010 ◽  
Vol 17 (02) ◽  
pp. 173-176 ◽  
Author(s):  
BYUNG SUN HAN ◽  
YOUNG RANG UHM ◽  
CHANG KYU RHEE
Keyword(s):  
Acetic Acid ◽  
Morphological Changes ◽  
Distilled Water ◽  
X Ray Diffraction ◽  
Temperature Method ◽  
Diffraction Patterns ◽  
Rapid Hydrolysis ◽  
Zno Powder ◽  
Hydrolysis Of

ZnO with 2D flower-like and 1D rod shape were obtained from simple and rapid hydrolysis of Zn nanopowder. The Zn nanopowders were incorporated into distilled water with acetic acid and then the solution was stirred at 60°C for 8 h. The nanoflower-like and rod shape were formed without any surfactant. It seems that the acetic acid played a role of controlling PH and etching the oxide layer on the surface of metal nanopowders to enhance rapid reaction with distilled water. X-ray diffraction patterns for all samples exhibited that the resultant precipitates were completely transformed to ZnO powder. It is clearly observed that the morphological changes of ZnO with reaction time in aqueous solution follows chestnut bur → flower → tetrahedron → rod sequences during the hydrolysis reaction.

Synthesis and Characterization of Gadolinia-Doped Ceria with Manganese Addition

2012 ◽  
Vol 727-728 ◽  
pp. 1296-1301
Author(s):  
J.D. Yang ◽  
R.A. Rocha ◽  
R. Muccillo ◽  
E.N.S. Muccillo
Keyword(s):  
Single Phase ◽  
Powder Materials ◽  
Doped Ceria ◽  
X Ray Diffraction ◽  
Cation Complexation ◽  
Wide Range ◽  
Diffraction Patterns ◽  
Etched Surface

Ceria-based materials have been extensively studied due to their wide range of technological application. In this work, nanostructured powders of 20 mol% gadolinia-doped ceria pure and containing 1 mol% manganese were synthesized by the cation complexation technique. Powder materials were calcined at 600°C, uniaxially pressed and sintered in the 1200-1500°C range for soaking times of 1, 2 and 4 h. X-ray diffraction patterns evidenced a single-phase fluorite-like structure in all studied specimens. The evolution of grain sizes was evaluated by scanning electron microscopy on polished and thermally etched surface of sintered pellets. The relative density decreases for soaking times above 1300°C (with Mn) and 1400°C (without Mn). The grain size increases with manganese addition. The role of the additive on the electrical conductivity of gadolinia-doped ceria was evaluated by impedance spectroscopy measurements.

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