scholarly journals The derivation of the cellulose microfibril angle by small-angle X-ray scattering from structurally characterized softwood cell-wall populations

2005 ◽  
Vol 38 (3) ◽  
pp. 505-511 ◽  
Author(s):  
Kenneth M. Entwistle ◽  
Stephen J. Eichhorn ◽  
Namasivayam Navaranjan
Keyword(s):  
Cell Wall ◽  
Standard Deviation ◽  
Intensity Distribution ◽  
Cell Walls ◽  
Radial Direction ◽  
Microfibril Angle ◽  
Scattered Intensity ◽  
X Ray ◽  
The Real ◽  
X Ray Scattering

A method is presented for the measurement, using small-angle X-ray scattering (SAXS), of the microfibril angle and the associated standard deviation for the cellulose microfibrils in the S2 layer of the cell walls of softwood specimens. The length and orientation of over 1000 cell walls in the irradiated volume of the specimen are measured using quantitative image analysis. From these data are calculated the azimuthal variation of the scattered intensity. The calculated values are compared with the measured values. The undetermined parameters in the analysis are the microfibril angle (M) and the standard deviation (σΦ) of the intensity distribution arising from the wandering of the fibril orientation about the mean value. The two parameters are varied to give the best fit between the calculated and the measured values. Six separate pairs of values are determined for six different values of the angle of incidence of the X-ray beam relative to the normal to the radial direction in the specimen. The results show good agreement. The azimuthal distribution of scattered intensity for the real cell-wall structure is compared with that calculated for an assembly of rectangular cells with the same ratio of transverse to radial cell-wall lengths. Despite the existence of marked differences in the intensity distributions around the zero azimuth angle, the position of the extreme flanks of the distribution is very close for the real and the rectangular cells. This means that useful values of the microfibril angle can be obtained from the curve for the real cells using the Meylan parameter T derived by drawing tangents to the flanks of the intensity distribution and using M = kT. The value of k is M/(M + 2σΦ). Since both of these parameters are determined in the work now described, k is also determined. It is also demonstrated that for β = 45° (where β is the angle between the plane face of the wood specimens and the radial direction) the peaks in the azimuthal intensity distribution for the real and the rectangular cells coincide. If this peak position is Φ45, then the microfibril angle can be determined from the relation M = tan−1(tanΦ45/cos45°), which is precise for rectangular cells.

Application of Small-Angle X-Ray Scattering to Predict Microfibril Angle in Acacia mangium Wood

2010 ◽  
Vol 173 ◽  
pp. 72-77
Author(s):  
Tabet A. Tamer ◽  
Aziz Abdul Haji Fauziah ◽  
Radiman Shahidan
Keyword(s):  
Cell Wall ◽  
Standard Deviation ◽  
Intensity Distribution ◽  
Small Angle ◽  
Cell Walls ◽  
Microfibril Angle ◽  
Acacia Mangium ◽  
Cellulose Microfibrils ◽  
X Ray ◽  
X Ray Scattering

Partially crystalline cellulose microfibrils are wound helically around the longitudinal axis of the wood cell. A method is presented for the measurement, using small-angle X-ray scattering (SAXS), of the microfibril angle, (MFA) and the associated standard deviation for the cellulose microfibrils in the S2 layer of the cell walls of Acacia mangium wood. The length and orientation of the microfibrils of the cell walls in the irradiated volume of the thin samples are measured using SAXS and scanning electron microscope, (SEM). The undetermined parameters in the analysis are the MFA, (M) and the standard deviation (σФ) of the intensity distribution arising from the wandering of the fibril orientation about the mean value. Nine separate pairs of values are determined for nine different values of the angle of the incidence of the X-ray beam relative to the normal to the radial direction in the sample. The results show good agreement. The curve distribution of scattered intensity for the real cell wall structure is compared with that calculated with that assembly of rectangular cells with the same ratio of transverse to radial cell wall length. It is demonstrated that for β = 45°, the peaks in the curve intensity distribution for the real and the rectangular cells coincide. If this peak position is Ф45, Then the MFA can be determined from the relation M = tan-1 (tan Ф45 / cos 45°), which is precise for rectangular cells.

scholarly journals Even Visually Intact Cell Walls in Waterlogged Archaeological Wood Are Chemically Deteriorated and Mechanically Fragile: A Case of a 170 Year-Old Shipwreck

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1113 ◽  
Author(s):  
Liuyang Han ◽  
Xingling Tian ◽  
Tobias Keplinger ◽  
Haibin Zhou ◽  
Ren Li ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Intact Cell ◽  
Nitrogen Adsorption ◽  
Wet Chemistry ◽  
Archaeological Wood ◽  
Waterlogged Archaeological Wood ◽  
X Ray Scattering ◽  
Crystallite Structure ◽  
Cell Wall Mechanics

Structural and chemical deterioration and its impact on cell wall mechanics were investigated for visually intact cell walls (VICWs) in waterlogged archaeological wood (WAW). Cell wall mechanical properties were examined by nanoindentation without prior embedding. WAW showed more than 25% decrease of both hardness and elastic modulus. Changes of cell wall composition, cellulose crystallite structure and porosity were investigated by ATR-FTIR imaging, Raman imaging, wet chemistry, 13C-solid state NMR, pyrolysis-GC/MS, wide angle X-ray scattering, and N2 nitrogen adsorption. VICWs in WAW possessed a cleavage of carboxyl in side chains of xylan, a serious loss of polysaccharides, and a partial breakage of β-O-4 interlinks in lignin. This was accompanied by a higher amount of mesopores in cell walls. Even VICWs in WAW were severely deteriorated at the nanoscale with impact on mechanics, which has strong implications for the conservation of archaeological shipwrecks.

The effects of thermal treatment on the nanomechanical behavior of bamboo (Phyllostachys pubescens Mazel ex H. de Lehaie) cell walls observed by nanoindentation, XRD, and wet chemistry

Holzforschung ◽  
2017 ◽  
Vol 71 (2) ◽  
pp. 129-135 ◽  
Author(s):  
Yanjun Li ◽  
Chengjian Huang ◽  
Li Wang ◽  
Siqun Wang ◽  
Xinzhou Wang
Keyword(s):  
Cell Wall ◽  
Thermal Treatment ◽  
Cell Walls ◽  
Treatment Time ◽  
Lignin Content ◽  
Phyllostachys Pubescens ◽  
X Ray Diffraction ◽  
Wet Chemistry ◽  
X Ray ◽  
Wet Chemical

Abstract The effects of thermal treatment of bamboo at 130, 150, 170, and 190°C for 2, 4, and 6 h were investigated in terms of changes in chemical composition, cellulose crystallinity, and mechanical behavior of the cell-wall level by means of wet chemical analysis, X-ray diffraction (XRD), and nanoindentation (NI). Particularly, the reduced elastic modulus (Er), hardness (H), and creep behavior were in focus. Both the temperature and treatment time showed significant effects. Expectedly, the hemicelluloses were degraded and the relative lignin content was elevated, while the crystallinity of the cellulose moiety was increased upon thermal treatment. The Er and H data of the cell wall were increased after 6 h treatment at 190°C, from 18.4 to 22.0 GPa and from 0.45 to 0.65 GPa, respectively. The thermal treatment led to a decrease of the creep ratio (CIT) under the same conditions by ca. 28%. The indentation strain state (εi) also decreased significantly after thermal treatment during the load-holding stage.

Interpretation of small-angle x-ray scattering intensity distribution from fluctuating lamellae in a ternary system: sodium octyl sulfate-water-decanol

Langmuir ◽  
1991 ◽  
Vol 7 (9) ◽  
pp. 1895-1899
Author(s):  
Eric Y. Sheu ◽  
Sow Hsin. Chen ◽  
Bruce L. Carvalho ◽  
J. S. Lin ◽  
Malcolm. Capel
Keyword(s):  
Ternary System ◽  
Intensity Distribution ◽  
Small Angle ◽  
Scattering Intensity ◽  
X Ray ◽  
X Ray Scattering ◽  
System Sodium ◽  
Ray Scattering

Microfibril Angle: Measurement, Variation and Relationships – A Review

IAWA Journal ◽  
2008 ◽  
Vol 29 (4) ◽  
pp. 345-386 ◽  
Author(s):  
Lloyd Donaldson
Keyword(s):  
Cell Wall ◽  
Large Scale ◽  
Juvenile Wood ◽  
Microfibril Angle ◽  
Basic Density ◽  
Angle Measurement ◽  
Axial Stiffness ◽  
Timber Species ◽  
Increment Core ◽  
X Ray

Microfibril angle (MFA) is perhaps the easiest ultrastructural variable to measure for wood cell walls, and certainly the only such variable that has been measured on a large scale. Because cellulose is crystalline, the MFA of the S2 layer can be measured by X-ray diffraction. Automated X-ray scanning devices such as SilviScan have produced large datasets for a range of timber species using increment core samples. In conifers, microfibril angles are large in the juvenile wood and small in the mature wood. MFA is larger at the base of the tree for a given ring number from the pith, and decreases with height, increasing slightly at the top tree. In hardwoods, similar patterns occur, but with much less variation and much smaller microfibril angles in juvenile wood. MFA has significant heritability, but is also influenced by environmental factors as shown by its increased values in compression wood, decreased values in tension wood and, often, increased values following nutrient or water supplementation. Adjacent individual tracheids can show moderate differences in MFA that may be related to tracheid length, but not to lumen diameter or cell wall thickness. While there has been strong interest in the MFA of the S2 layer, which dominates the axial stiffness properties of tracheids and fibres, there has been little attention given to the microfibril angles of S1 and S3 layers, which may influence collapse resistance and other lateral properties. Such investigations have been limited by the much greater difficulty of measuring angles for these wall layers. MFA, in combination with basic density, shows a strong relationship to longitudinal modulus of elasticity, and to longitudinal shrinkage, which are the main reasons for interest in this cell wall property in conifers. In hardwoods, MFA is of more interest in relation to growth stress and shrinkage behaviour.

Wood Petrifaction: and aspect of biomineralogy

1979 ◽  
Vol 27 (4) ◽  
pp. 377 ◽  
Author(s):  
G Scurfield
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
X Ray Diffraction ◽  
Intercellular Substance ◽  
X Ray ◽  
Colloidal Form ◽  
Cell Lumina ◽  
Mineral Deposition ◽  
Wall Components ◽  
Scanning Electron

Light microscopy, scanning electron microscopy, X-ray diffraction and differential thermal analysis have been used to examine the structure and mineralogical make-up of 79 Australian petrified woods. Initiation of petrifaction appears to rely on the provision of a substrate with inherent porosity, with the substrate components chemically rather inert and only slowly degraded at normal temperatures and pressures under conditions probably most often acid and tending to anaerobic, and the pores sufficiently large to allow access of an appropriate mineral in ionic or colloidal form in water. Stages in the process include entry of mineral solution into the wood via splits or checks, cell lumina, and other voids; permeation of cell walls; progressive dissolution of cell wall components beginning largely with lignin and accompanied by a build-up of a mineral framework adequate for maintaining the dimensional stability of the wood; mineral deposition in cell lumina after cell wall replacement as a continuous, intermittent, perhaps separate, but not obligatory event; mineral deposition in voids present or formed by dissolution of intercellular substance as a separate, but not obligatory event; and final lithification involving loss of water and perhaps replacement of one mineral by another.

SWING detection vacuum tunnel

2011 ◽  
Vol 1 (MEDSI-6) ◽  
Author(s):  
D. Dalle ◽  
J. Perez ◽  
O. Lyon ◽  
P. Feret ◽  
C. Menneglier ◽  
...  
Keyword(s):  
Small Angle ◽  
Vacuum Chamber ◽  
Incident Beam ◽  
Angular Range ◽  
Scattered Intensity ◽  
Long Distance ◽  
General Design ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

The SWING beamline is dedicated to the study of the small-angle X-ray scattering. In order to have the possibility to detect scattered intensity very close to the incident beam, it is absolutely necessary to install the detector at a long distance from the sample. In addition, it is easy to change the detector's position to access a wider angular range. A long and large vacuum chamber, the ‘tunnel’, has been designed with specific mechanisms inside to control the detector's position with micrometre resolution. Special attention has been given so as to offer a very useful device to the users. The paper will present the general design of the tunnel equipped with ancillary devices such as very narrow and stiff beam stoppers, diode holders and beam attenuators.

Osmium Staining Fails to Detect Early Cell Wall Damage in Brown Rot Wood Decay

IAWA Journal ◽  
1994 ◽  
Vol 15 (2) ◽  
pp. 133-136
Author(s):  
W. Wayne Wilcox
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Cell Walls ◽  
Osmium Tetroxide ◽  
Wood Decay ◽  
Brown Rot ◽  
X Ray ◽  
Polarised Light ◽  
Early Manifestation ◽  
Scanning Electron

Loss of cell wall birefringence under polarised light in the light microscope is an important diagnostic characteristic for early stages of brown rot wood decay not available with the scanning electron microscope (SEM). Osmium tetroxide staining was explored as a means of visualising this early manifestation of decay in the SEM, but proved unsuccessful as X-ray spectroscopy indicated that osmium was evenly distributed across both distorted and non-distorted cell walls.

The information available from anomalous scattering on fibres at different wavelengths

1987 ◽  
Vol 20 (4) ◽  
pp. 295-299 ◽  
Author(s):  
C. Nave
Keyword(s):  
Absorption Edge ◽  
Heavy Atom ◽  
Imaginary Component ◽  
Anomalous Scattering ◽  
Phase Problem ◽  
Phase Information ◽  
Helical Symmetry ◽  
X Ray ◽  
The Real ◽  
X Ray Scattering

The contribution of a particular atom in a molecule to the total X-ray scattering can be altered by varying the wavelength in the region of the absorption edge of the atom. It is shown that only the changes in the real part of the anomalous scattering of the atom provide significant changes in a pattern from a fibre containing molecules with helical symmetry. Changes due to the imaginary component are small and Friedel differences cannot be observed, owing to the fibre disorder. The information which can be obtained is equivalent to that given by a truly isomorphous heavy-atom derivative. For the general case this is not sufficient to provide unambiguous phase information. If a twofold axis is present at right angles to the fibre axis then the amplitudes are real and the phase problem can, in favourable cases, be solved.

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