| 1. |
|
|
| 2. |
- Joseph, P., et al.
(författare)
-
Morphology of lignin structures on fiber surfaces after organosolv pretreatment
- 2022
-
Ingår i: Biopolymers. - : John Wiley and Sons Inc. - 0006-3525 .- 1097-0282. ; 113:9
-
Tidskriftsartikel (refereegranskat)abstract
- The redeposition of lignin to the fiber surface after organosolv pretreatment was studied using two different reactor types. Results from the conventional autoclave reactor suggest that redeposition occurs during the cooling down stage. Redeposited particles appeared to be spherical in shape. The size and population density of the particles depends on the concentration of organosolv lignin in the cooking liquor, which is consistent with the hypothesis that reprecipitation of lignin occurs when the system is cooled down. The use of a displacement reactor showed that displacing the spent cooking liquor with fresh cooking liquor helps in reducing the redeposition and the inclusion of a washing stage with fresh cooking liquor reduced the reprecipitation of lignin, particularly on the outer fiber surfaces. Redeposition of lignin was still observed on regions that were less accessible to washing liquid, such as fiber lumens, suggesting that complete prevention of redeposition was not achieved. © 2022 The Authors.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Ottesen, V, et al.
(författare)
-
Nanocellulose in Paper and Packaging
- 2014
-
Konferensbidrag (refereegranskat)abstract
- One possible way to improve competitiveness of paper materials is through utilization of nanocellulose to achieve new properties or to reduce production cost. Several studies have shown that nanofibrillar cellulose (NFC) can act as strength enhancing additive in paper or for paper surface improvements. NFC has the potential to bind large amounts of inorganic fillers in the paper sheet, and by this reduce energy consumption during paper production considerably. However, there are challenges that need to be addressed before the novel concepts can be realized, e.g. impaired drainage and drying of paper resulting from addition of NFC. This may be solved by obtaining the right balance between NFC quality, chemicals and additives. Promising results in this respect have been obtained but this is still in an early stage. Fiber-based packaging materials represent a “green” alternative to petroleum based packaging solutions. Depending on the packaging category, different properties are important. For the segment liquid packaging board, barrier against oxygen is important. Currently, this is obtained by using aluminum, or the petroleum-based polymer EVOH in combination with a water barrier. Replacing these materials with “green” alternatives would represent a large environmental achievement. While superior oxygen barrier properties has been demonstrated for NFC, good barrier against water and oxygen requires the combination of nanofibrils with complementary materials. Adequate combinations with other materials and feasible application techniques are still challenges that need to be solved. Other packaging segments require other properties, e.g. high stiffness or fracture toughness. By development of appropriate nanocellulose qualities, such properties can be improved. By preparing fibrils with small diameter, translucent films can be prepared. This is an interesting property for food packaging, where transparency may be a desired trait.
|
|
| 7. |
- Ottesen, V, et al.
(författare)
-
Nanocellulose Properties of Interest for Paper and Packaging
- 2014
-
Konferensbidrag (refereegranskat)abstract
- Cellulose Nano-Fibrils (CNF) is a biocompatible nano-material with appealing mechanical and optical properties. The high specific surface area (SSA) of nanofibrils ensure that a large fraction of the polymer chains in each fibril are surface fibrils, meaning numerous surface hydroxyl groups will be available to form bonds between components in the paper, ensuring high density and strength. CNF may be added to conventional paper as a strengthening agent. CNF films may be used as a barrier coating, or CNF sheets may be used in a number of products due to their potential transparency, strength and barrier properties. As a paper additive, CNF as a nanomaterial acts as a material that increases density and form bonds between fibers in the paper, providing an increased strength and stiffness whereas dusting and permeability is reduced. For papers where strength is chiefly limited by inter-fiber bonding strength, increases in excess of 100 % may be achieved by addition of small amounts of CNF. Less, but still significant contributions can be seen for papers whose strength is less dependent on inter-fiber bonding strength. Due to the pore-blocking properties of CNF coupled with Cellulose’s hydrophilic properties, dewatering on the paper machine is a challenge when CNF is used in this fashion. The high density, viz. the low porosity and small pore size (~0.47 nm), of CNF films provide a significant reduction in mass-transport. Applying such a film to a less efficient barrier material, or producing a pure CNF film presents oxygen transfer rates comparable with the best synthetic polymer films produced for this purpose. Sheets of pure CNF or a CNF composite may transmit 90 % of incident light with a wavelength of 600 nm. This transparency is due to the high density and small fibril size in sheets of pure CNF or a CNF-based composite, which results in a lower scattering coefficient compared to corresponding conventional fiber based sheets. Transparent sheets such as these may be of interest in packaging applications where the packaged goods, such as foodstuffs or luxury articles, is desired displayed to the end customer. The properties of CNF, whether as a film, a paper additive or a major paper or composite component may be of significant industrial interest due to the unique properties of the material.
|
|
| 8. |
|
|
| 9. |
- Villa, Luisa L., et al.
(författare)
-
Quadrivalent vaccine against human papillomavirus to prevent high-grade cervical lesions
- 2007
-
Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 356:19, s. 1915-1927
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Human papillomavirus types 16 (HPV-16) and 18 (HPV-18) cause approximately 70% of cervical cancers worldwide. A phase 3 trial was conducted to evaluate a quadrivalent vaccine against HPV types 6, 11, 16, and 18 (HPV-6/11/16/18) for the prevention of high-grade cervical lesions associated with HPV-16 and HPV-18. METHODS: In this randomized, double-blind trial, we assigned 12,167 women between the ages of 15 and 26 years to receive three doses of either HPV-6/11/16/18 vaccine or placebo, administered at day 1, month 2, and month 6. The primary analysis was performed for a per-protocol susceptible population that included 5305 women in the vaccine group and 5260 in the placebo group who had no virologic evidence of infection with HPV-16 or HPV-18 through 1 month after the third dose (month 7). The primary composite end point was cervical intraepithelial neoplasia grade 2 or 3, adenocarcinoma in situ, or cervical cancer related to HPV-16 or HPV-18. RESULTS: Subjects were followed for an average of 3 years after receiving the first dose of vaccine or placebo. Vaccine efficacy for the prevention of the primary composite end point was 98% (95.89% confidence interval [CI], 86 to 100) in the per-protocol susceptible population and 44% (95% CI, 26 to 58) in an intention-to-treat population of all women who had undergone randomization (those with or without previous infection). The estimated vaccine efficacy against all high-grade cervical lesions, regardless of causal HPV type, in this intention-to-treat population was 17% (95% CI, 1 to 31). CONCLUSIONS: In young women who had not been previously infected with HPV-16 or HPV-18, those in the vaccine group had a significantly lower occurrence of high-grade cervical intraepithelial neoplasia related to HPV-16 or HPV-18 than did those in the placebo group.
|
|
