Quantifying Localized Macromolecular Dynamics within Hydrated Cellulose Fibril Aggregates

2019 ◽  
Vol 52 (19) ◽  
pp. 7278-7288 ◽  
Author(s):  
Pan Chen ◽  
Camilla Terenzi ◽  
István Furó ◽  
Lars A. Berglund ◽  
Jakob Wohlert
Keyword(s):  
Cellulose Fibril ◽  
Hydrated Cellulose ◽  
Macromolecular Dynamics ◽  
Fibril Aggregates

Ultrastructural changes in a holocellulose pulp revealed by enzymes, thermoporosimetry and atomic force microscopy

Holzforschung ◽  
2005 ◽  
Vol 59 (6) ◽  
pp. 589-597 ◽  
Author(s):  
Jesper Fahlén ◽  
Lennart Salmén
Keyword(s):  
Atomic Force Microscopy ◽  
Kraft Pulp ◽  
Enzymatic Treatment ◽  
Ultrastructural Changes ◽  
Cellulose Fibril ◽  
Force Microscopy ◽  
Fibre Wall ◽  
Atomic Force ◽  
Pulp Fibres ◽  
Fibril Aggregates

Abstract To increase our knowledge of the ultrastructure within softwood fibres, enzymatic treatment, thermoporosimetry, light microscopy, and atomic force microscopy with image analysis were used to investigate the structure of holocellulose softwood pulp fibres. The size of the average cellulose fibril aggregates and the width of pore and matrix lamellae were found to be uniform across the secondary cell-wall layer in the transverse direction of the wood fibre wall. In holocellulose, these dimensions were very similar to those in the native wood, whereas in kraft pulp the cellulose fibril aggregates were larger and the pore and matrix lamellae broader. These differences between holocellulose and kraft pulp fibres suggest that a high temperature is needed for cellulose fibril aggregation to occur. Neither refining nor drying of the holocellulose pulp changed the cellulose fibril aggregate size. Upon drying and enzymatic treatment, a small decrease in the pore and matrix lamella width was evident throughout the fibre wall. This indicated not only uniform distribution of pores throughout the fibre wall, but also enzymatic accessibility to the entire fibre wall. The holocellulose pulp had a somewhat larger pore volume than the kraft pulp. Refining of the holocellulose pulp led to pore closure, probably due to increased mobility of the fibre wall. The enzymatic treatment revealed that during hydrolysis of one hemicellulose, part of the other was also dissolved, indicating that the two hemicelluloses are to some extent linked to each other in the structure.

Cross polarisation/magic angle spinning 13C-NMR spectroscopic studies of cellulose structural changes in hardwood dissolving pulp process

Holzforschung ◽  
2007 ◽  
Vol 61 (6) ◽  
pp. 675-679 ◽  
Author(s):  
Xolani Nocanda ◽  
Per Tomas Larsson ◽  
Andrew Spark ◽  
Tamara Bush ◽  
Ann Olsson ◽  
...  
Keyword(s):  
Surface Area ◽  
Structural Changes ◽  
Magic Angle Spinning ◽  
Dissolving Pulp ◽  
Magic Angle ◽  
Cellulose Fibril ◽  
Dissolving Pulps ◽  
Angle Spinning ◽  
Fibril Aggregates ◽  
Pulp Process

Abstract Cross polarisation/magic angle spinning 13C NMR spectroscopy has been used to study structural changes in cellulose induced by the dissolving pulp process. The cellulose structure in several dissolving pulps was investigated for commercial and laboratory cooked Eucalyptus 92α and 96α. The average lateral dimension, or average thickness, of the cellulose fibril aggregates is related to the amount of surface area exposed and could be one controlling factor for the chemical reactivity of commercial dissolving pulps during modification reactions. The thickness of the cellulose fibril aggregates governs the amount of surface area present in the fibre wall, and cellulose surface material constitutes the part of the cellulose that is directly accessible to reagents. In all sample series investigated, the raw pulp was found to be less aggregated than the corresponding bleached final pulp. Furthermore, an irreversible increase in fibril aggregate width was observed on free drying for both laboratory cooked and commercial pulps. Upon rewetting with water, the freely dried 96α pulp was found to be more aggregated than the freely dried 92α pulp, although sugar analysis showed very similar carbohydrate compositions. As indicated by the molecular mass distribution, the commercial 92α pulp contained larger amounts of degraded cellulose; this may be a plausible explanation for the different behaviour of the 92α and 96α pulps during free drying.

scholarly journals The Ultrastructure of Tissue Damage by Amyloid Fibrils

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4611
Author(s):  
Haruki Koike ◽  
Masahisa Katsuno
Keyword(s):  
Tissue Damage ◽  
Amyloid Fibrils ◽  
Amyloid Fibril ◽  
Prion Diseases ◽  
Nerve Biopsy ◽  
Al Amyloidosis ◽  
Amyloid Fibril Formation ◽  
Autopsy Specimens ◽  
Fibril Aggregates ◽  
Interfering Rna

Amyloidosis is a group of diseases that includes Alzheimer’s disease, prion diseases, transthyretin (ATTR) amyloidosis, and immunoglobulin light chain (AL) amyloidosis. The mechanism of organ dysfunction resulting from amyloidosis has been a topic of debate. This review focuses on the ultrastructure of tissue damage resulting from amyloid deposition and therapeutic insights based on the pathophysiology of amyloidosis. Studies of nerve biopsy or cardiac autopsy specimens from patients with ATTR and AL amyloidoses show atrophy of cells near amyloid fibril aggregates. In addition to the stress or toxicity attributable to amyloid fibrils themselves, the toxicity of non-fibrillar states of amyloidogenic proteins, particularly oligomers, may also participate in the mechanisms of tissue damage. The obscuration of the basement and cytoplasmic membranes of cells near amyloid fibrils attributable to an affinity of components constituting these membranes to those of amyloid fibrils may also play an important role in tissue damage. Possible major therapeutic strategies based on pathophysiology of amyloidosis consist of the following: 1) reducing or preventing the production of causative proteins; 2) preventing the causative proteins from participating in the process of amyloid fibril formation; and/or 3) eliminating already-deposited amyloid fibrils. As the development of novel disease-modifying therapies such as short interfering RNA, antisense oligonucleotide, and monoclonal antibodies is remarkable, early diagnosis and appropriate selection of treatment is becoming more and more important for patients with amyloidosis.

scholarly journals 3DEM Loupe: analysis of macromolecular dynamics using structures from electron microscopy

2013 ◽  
Vol 41 (W1) ◽  
pp. W363-W367 ◽  
Author(s):  
R. Nogales-Cadenas ◽  
S. Jonic ◽  
F. Tama ◽  
A. A. Arteni ◽  
D. Tabas-Madrid ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Macromolecular Dynamics

Porosity and opticomechanical properties of hydrated cellulose membranes

1990 ◽  
Vol 26 (1) ◽  
pp. 124-130
Author(s):  
I. V. Grushetskii ◽  
V. M. Parfeev ◽  
N. A. Vengerova ◽  
A. R. Rudman ◽  
V. B. Eremeev
Keyword(s):  
Hydrated Cellulose ◽  
Cellulose Membranes

scholarly journals Changes in the cellulose fiber wall supramolecular structure during the initial stages of chemical treatments of wood evaluated by NMR and X-ray scattering

Cellulose ◽  
2021 ◽  
Vol 28 (7) ◽  
pp. 3951-3965
Author(s):  
Elisabet Brännvall ◽  
P. Tomas Larsson ◽  
Jasna S. Stevanic
Keyword(s):  
Supramolecular Structure ◽  
Aggregate Size ◽  
Cellulose Fiber ◽  
Effect Of Temperature ◽  
Cellulose Fibril ◽  
X Ray ◽  
X Ray Scattering ◽  
Fiber Wall ◽  
The Impact ◽  
Ray Scattering

AbstractThe effect of initial stages of pulping of spruce, resembling prehydrolysis and alkaline cooking was studied using CP/MAS 13C-NMR, X-ray scattering, FSP and carbohydrate composition in order to study the impact of the pre-treatments on the fiber wall nanostructure. Removal of fiber wall components, hemicellulose and lignin, increased the fiber wall porosity and induced cellulose fibril aggregation. The effect of temperature and pH in the treatment on cellulose fibril aggregate size appears to be secondary. It is the removal of hemicellulose that has a profound effect on the supramolecular structure of the cellulose fiber wall. As the amount of hemicellulose dissolved from wood increases, the fibril aggregate size determined by NMR increases as well, ranging from 16 to 28 nm. Specifically, a good correlation between the amount of glucomannan in the fiber wall and the fibril aggregate size is seen. The lower the amount of glucomannan, the larger the aggregate size. Glucomannan thus seems to prevent aggregation as it acts as a very efficient spacer between fibrils. Elemental fibril size determined by NMR, was quite similar for all samples, ranging from 3.6 to 4.1 nm. By combining measurement methods, a more well-resolved picture of the structural changes occurring during was obtained.

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