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- Henriksson, Gunnar, 1965-, et al.
(author)
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Monocomponent endoglucanases : an excellent tool in wood chemistry and pulp processing
- 2005
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In: 13th ISWFPC (International Symposium on Wood, Fibre and Pulping Chemistry), Auckland, New Zealand, 16-19 May 2005: Proceedings. ; , s. 503-508
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Conference paper (peer-reviewed)abstract
- Highly pure cellulases of endoglucanase type produced by genetically modified fungi are commercially available. They are useful tools both for analytical wood chemistry and potentially also as industrial chemicals for novel processes for the pulp and paper industry. Here the functionality of cellulases and some application of endoglucanases are reviewed. The mechanisms behind the effects of the enzyme are discussed.
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| 2. |
- Henriksson, Marielle, et al.
(author)
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An environmentally friendly method for enzyme-assisted preparation of microfibrillated cellulose (MFC) nanofibers
- 2007
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In: European Polymer Journal. - : Elsevier BV. - 0014-3057 .- 1873-1945. ; 43:8, s. 3434-3441
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Journal article (peer-reviewed)abstract
- Microfibrillated cellulose nanofibers (MFC) provide strong reinforcement in polymer nanocomposites. In the present study, cellulosic wood fiber pulps are treated by endoglucanases or acid hydrolysis in combination with mechanical shearing in order to disintegrate MFC from the wood fiber cell wall. After successful disintegration, the MFC nanofibers were studied by atomic force microscopy (AFM). Enzyme-treatment was found to facilitate disintegration, and the MFC nanofibers produced also showed higher average molar mass and larger aspect ratio than nanofibers resulting from acidic pretreatment.
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| 6. |
- Dvinskikh, Sergey V., et al.
(author)
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A multinuclear magnetic resonance imaging (MRI) study of wood with adsorbed water : Estimating bound water concentration and local wood density
- 2011
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In: Holzforschung. - 0018-3830 .- 1437-434X. ; 65:1, s. 103-107
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Journal article (peer-reviewed)abstract
- The interaction between moisture and the macromolecular wood tissue is of critical importance to wood properties. In this context, magnetic resonance imaging (MRI) is very promising as this method could deliver molecular information on the submillimeter scale (i.e., along concentration gradients) about both free and adsorbed water and the cell wall polymers. In the present study, it is demonstrated for the first time that wood containing adsorbed heavy water ((H2O)-H-2) can be studied by MRI based on separated images due to water (H-2 MRI) and cell wall polymers (H-1 MRI). Data confirm that in specimens equilibrated at controlled humidity there is a direct correlation between bound water content and relative density of the polymers in wood tissue; there is a strong variation across annual rings.
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| 7. |
- Dvinskikh, Sergey V., et al.
(author)
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NMR imaging study and multi-Fickian numerical simulation of moisture transfer in Norway spruce samples
- 2011
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In: Engineering structures. - : Elsevier BV. - 0141-0296 .- 1873-7323. ; 33:11, s. 3079-3086
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Journal article (peer-reviewed)abstract
- Wood has potential as a renewable material for a large variety of applications that often call for improved properties such as dimensional stability, moisture insensitivity, and durability. Moisture migration in wood is a particularly important factor in determining the cost-effective service life of wooden construction. Within the present research, proton NMR imaging was applied for recording the moisture spatial distribution of various samples of Norway Spruce. Moisture distribution along the radial, tangential and longitudinal directions in wood was monitored at different times upon three consecutive changes of relative humidity: (1) from 65% to 94%; (2) from 94% to 33%; (3) from 33% to 65%. Uncoated samples and specimens treated with different types of surface coatings were studied. The experiments were numerically simulated by using the multi-Fickian model. The model describes the moisture transport process in wood which is characterized by three phenomena: (a) bound water diffusion, (b) water vapor diffusion and (c) coupling between the two phases through sorption. The model is implemented into the Abaqus FEM code. The numerical results are found to be in agreement with the experimental data.
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| 8. |
- Fall, Andreas, et al.
(author)
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The effect of ionic strength and pH on the dewatering rate of cellulose nanofibril dispersions
- 2022
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In: Cellulose. - : Springer Science and Business Media B.V.. - 0969-0239 .- 1572-882X. ; 29:14, s. 7649-7662
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Journal article (peer-reviewed)abstract
- Cellulose nanofibrils, CNFs, show great potential in many application areas. One main aspect limiting the industrial use is the slow and energy demanding dewatering of CNF suspensions. Here we investigate the dewatering with a piston press process. Three different CNF grades were dewatered to solid contents between approx. 20 and 30%. The CNF grades varied in charge density (30, 106 and 604 µmol/g) and fibrillation degree. The chemical conditions were varied by changing salt concentration (NaCl) and pH and the dewatering rates were compared before and after these changes. For the original suspensions, a higher charge provides slower dewatering with the substantially slowest dewatering for the highest charged CNFs. However, by changing the conditions it dewatered as fast as the two lower charged CNFs, even though the salt/acid additions also improved the dewatering rate for these two CNFs. Finally, by tuning the conditions, fast dewatering could be obtained with only minor effect on film properties (strength and oxygen barrier) produced from redispersed dispersion. However, dewatering gives some reduction in viscosity of the redispersed dispersions. This may be a disadvantage if the CNF application is as e.g. rheology modifier or emulsion stabilizer. Graphical abstract: [Figure not available: see fulltext.].
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| 9. |
- Heggset, Ellinor B, et al.
(author)
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Cellulose nanofibrils as rheology modifier in mayonnaise – A pilot scale demonstration
- 2020
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In: Food Hydrocolloids. - : Elsevier B.V.. - 0268-005X .- 1873-7137. ; 108
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Journal article (peer-reviewed)abstract
- The applicability of cellulose nanofibrils (CNFs) as viscosifying agent in a starch-reduced low-fat mayonnaise and in an oil-reduced full-fat mayonnaise has been considered. For low-fat mayonnaise a 50 wt% reduction in the ordinary starch content was performed, while for full-fat mayonnaise, the oil content was reduced from 79 to 70 wt%. To study if the stability was affected when CNFs were added, analyses as visual and accelerated stability tests, droplet size measurements and rheology studies, determining the shear viscosity, and the loss and storage moduli, were conducted after 1 day, 1 week and 1 month of storage in room temperature. Even though changes in droplet size distributions and rheological properties indicated some coalescence, the visual stability was not changed after 1 month of storage for any of the samples. The decrease in viscosity and moduli inflicted by reduction of starch or fat, could be regained by the addition of CNFs at 0.75 wt % and 0.42 wt %, respectively. Based on the results in this work, mayonnaise with reduced starch or fat content can be produced when CNFs are used as a viscosifying agent.
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