Effects of refining on the fibre structure of kraft pulps as revealed by FE-SEM and TEM: Influence of alkaline degradation

Holzforschung ◽  
2004 ◽  
Vol 58 (3) ◽  
pp. 226-232 ◽  
Author(s):  
U. Molin ◽  
G. Daniel
Keyword(s):  
Electron Microscopy ◽  
Intrinsic Viscosity ◽  
Fibre Length ◽  
Fibre Surface ◽  
Alkali Concentration ◽  
Kraft Pulps ◽  
Transmission Electron ◽  
Pulp Fibres ◽  
Pfi Refining ◽  
S2 Layer

Abstract The aim of the study was to evaluate the effect of refining on the ultrastructure of spruce pulp fibres. Pulps with different molar masses of cellulose (estimated as intrinsic viscosity) were studied after PFI-refining. The molar masses of the polymers were decreased by increases in alkali concentration during pulping. Fibre surface structures were examined using Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) was used to observe changes in the internal structure of the fibres. Pulps with lower (125 and 329 ml g−1) intrinsic viscosity showed more damaged during refining than pulps with higher (620 and 1120 ml g−1) intrinsic viscosity. Observations showed pulps with lower intrinsic viscosity to have large decreases in fibre length after refining. Fibres with low intrinsic viscosity (i.e., 125 ml g−1) had less primary wall and S1 layer remaining and the external fibrillation and damage of the S2 layer had increased. The S2 wall of fibres with high intrinsic viscosity showed characteristic delamination. Similar delamination was not visible for fibres with low intrinsic viscosity.

Sonochemical Fabrication and Characterization of Ceria (CeO2) Nanowires

2006 ◽  
Vol 6 (1) ◽  
pp. 157-161 ◽  
Author(s):  
Hong-Liang Chen ◽  
Hai-Yang Zhu ◽  
Hui Wang ◽  
Lin Dong ◽  
Jun-Jie Zhu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Microstructural Analysis ◽  
Specific Effect ◽  
Ambient Air ◽  
Growth Direction ◽  
Alkali Concentration ◽  
Sonochemical Method ◽  
Visible Absorption ◽  
Transmission Electron

Ceria (CeO2) nanowires have been successfully synthesized by a sonochemical method in ambient air and alkali aqueous solution from CeO2 nanoparticles without using any templates. The results showed that both alkali concentration and ultrasonic irradiation played critical roles in the formation of the nanowires. The crystalline structure and dimensions of the nanowires were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). The UV-visible absorption spectrum result showed that the products had conspicuous shape-specific effect. Microstructural analysis in HRTEM revealed that the preferential growth direction of CeO2 nanowires was [110]. Moreover, the catalytic activity of Au/CeO2 using CeO2 nanowires as support for CO conversion was higher than that obtained using bulk CeO2 as support.

Ultrastructural Localisation of Glucomannan in Kraft Pulp Fibres

Holzforschung ◽  
2003 ◽  
Vol 57 (1) ◽  
pp. 62-68 ◽  
Author(s):  
I. Duchesne ◽  
K. Takabe ◽  
G. Daniel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Kraft Pulp ◽  
Immunogold Labelling ◽  
Cellulose Microfibrils ◽  
Hemicellulose Content ◽  
Transmission Electron ◽  
Hemicellulose Removal ◽  
Pulp Fibres ◽  
Fibril Aggregates

Summary The localisation of glucomannan on the surface of Norway spruce kraft pulp fibres with varying glucomannan (GM) contents (10.3 and 3.8%) was studied using immunogold labelling, rapid freeze deep etching (RFDE) followed by metal replication and transmission electron microscopy (TEM). The ultrastructure of P, S1 and S2 of pulp fibres with low hemicellulose content tended to be more compact than that of pulp fibres with high hemicellulose content, suggesting aggregation of cellulose microfibrils upon hemicellulose removal. The degree of immunogold labelling visualised as globular structures was similar for the two pulps, despite the large difference in total glucomannan content. Thus, no correlation between the bulk and surface contents of glucomannan was found. The globular structures were heterogeneously located along the cellulose macrofibrils (fibril aggregates) and their frequency varied greatly within and between TEM micrographs.

Quantitative assessment of xylan distribution across the secondary cell wall layers of Eucalyptus dissolving pulp fibres

Holzforschung ◽  
2017 ◽  
Vol 72 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Prabashni Lekha ◽  
Tamara Bush ◽  
Norman Pammenter ◽  
Bruce Sitholè ◽  
Patricia Berjak
Keyword(s):  
Cell Wall ◽  
Secondary Cell Wall ◽  
Dissolving Pulp ◽  
Carbohydrate Binding ◽  
Transmission Electron ◽  
Wide Range ◽  
Pulp Fibres ◽  
S2 Layer ◽  
Selection Of ◽  
Specific Labelling

AbstractA quantitative method has been developed for assessment of the distribution of xylan across the secondary cell wall layers ofEucalyptusdissolving pulp fibres by means of a carbohydrate binding module (CBM),CtCBM6, in combination with transmission electron microscopy (TEM). To ensure reproducibility and to minimise non-specific labelling, various parameters were optimised, namely the size of the gold colloid marker,CtCBM6 concentration, and the selection of buffer solutions. The method was replicated on processedEucalyptusfibres containing different xylan contents. Reproducible xylan counts and distributions across the secondary cell wall layers were obtained for unbleached and bleachedEucalyptusfibres. The xylan distribution pattern across the cell wall layers S1, S2 and S3 was similar, but the S1 and S3 layers contained after bleaching more xylan than the S2 layer. The technique has a wide range of applications in basic wood research as well as in the analysis of technological processes.

The S2 Layer in the Tracheid Walls of Picea abies Wood: Inhomogeneity in Lignin Distribution and Cell Wall Microstructure

Holzforschung ◽  
2001 ◽  
Vol 55 (4) ◽  
pp. 373-378 ◽  
Author(s):  
Adya P. Singh ◽  
Geoffrey Daniel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Picea Abies ◽  
Lignin Distribution ◽  
Transmission Electron ◽  
S2 Layer ◽  
Tangential Directions ◽  
Electron Lucent

Summary Transmission electron microscopy (TEM) of the walls of Picea abies axial tracheids showed the distribution of lignin in the S2 layer to be inhomogenous. At relatively low magnifications, some parts of the outer and inner S2 layer appeared more electron dense than the mid region in the tracheids which were in contact with or in proximity to a ray. At similar magnifications, the presence of radial and tangential features was observed in the S2 layer of the tracheids which were in contact with or close to rays as well as in those which occurred elsewhere. Higher magnification views showed the S2 layer to be differentiated into electron lucent and dense regions in both radial and tangential directions. A comparison of the counts made of lignin particles in these regions suggested that the differentiation of the S2 wall into lucent and dense regions resulted from inhomogenous distribution of lignin observable at a nano level.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

Ultrastructural Analysis of the Salivary Glands of Gromphadorhina Portentosa (Schaum)

1977 ◽  
Vol 35 ◽  
pp. 638-639
Author(s):  
P.J. Dailey
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Salivary Glands ◽  
Secretory Vesicles ◽  
The Past ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Gromphadorhina Portentosa ◽  
Scanning Electron ◽  
Topographical Relief

The structure of insect salivary glands has been extensively investigated during the past decade; however, none have attempted scanning electron microscopy (SEM) in ultrastructural examinations of these secretory organs. This study correlates fine structure by means of SEM cryofractography with that of thin-sectioned epoxy embedded material observed by means of transmission electron microscopy (TEM).Salivary glands of Gromphadorhina portentosa were excised and immediately submerged in cold (4°C) paraformaldehyde-glutaraldehyde fixative1 for 2 hr, washed and post-fixed in 1 per cent 0s04 in phosphosphate buffer (4°C for 2 hr). After ethanolic dehydration half of the samples were embedded in Epon 812 for TEM and half cryofractured and subsequently critical point dried for SEM. Dried specimens were mounted on aluminum stubs and coated with approximately 150 Å of gold in a cold sputtering apparatus.Figure 1 shows a cryofractured plane through a salivary acinus revealing topographical relief of secretory vesicles.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

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