| 1. |
- Eichhorn, S. J., et al.
(författare)
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Current international research into cellulose as a functional nanomaterial for advanced applications
- 2022
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Ingår i: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 57:10, s. 5697-5767
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Tidskriftsartikel (refereegranskat)abstract
- This review paper provides a recent overview of current international research that is being conducted into the functional properties of cellulose as a nanomaterial. A particular emphasis is placed on fundamental and applied research that is being undertaken to generate applications, which are now becoming a real prospect given the developments in the field over the last 20 years. A short introduction covers the context of the work, and definitions of the different forms of cellulose nanomaterials (CNMs) that are most widely studied. We also address the terminology used for CNMs, suggesting a standard way to classify these materials. The reviews are separated out into theme areas, namely healthcare, water purification, biocomposites, and energy. Each section contains a short review of the field within the theme and summarizes recent work being undertaken by the groups represented. Topics that are covered include cellulose nanocrystals for directed growth of tissues, bacterial cellulose in healthcare, nanocellulose for drug delivery, nanocellulose for water purification, nanocellulose for thermoplastic composites, nanocellulose for structurally colored materials, transparent wood biocomposites, supercapacitors and batteries.
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| 2. |
- Lingois, P., et al.
(författare)
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Chemically induced residual stresses in dental composites
- 2003
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Ingår i: Journal of Materials Science. - 0022-2461 .- 1573-4803. ; 38:6, s. 1321-1331
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Tidskriftsartikel (refereegranskat)abstract
- In several European countries, dental composites are replacing mercury-containing amalgams as the most common restorative materials. One problem with dental composites is residual stresses which may lead to poor performance of the restoration. In the present study, a combined modeling and materials characterization approach is presented and predictions compare well with experimental data on residual stresses. The model takes stress relaxation into account through the complete relaxation time spectrum of the resin. The approach allows for detailed parametric studies where resin and composite composition as well as cure conditions may be tailored with respect to residual stress generation.
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| 3. |
- Varna, Janis, et al.
(författare)
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Crack opening geometry in cracked composite laminates
- 1997
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Ingår i: International journal of damage mechanics. - : SAGE Publications. - 1056-7895 .- 1530-7921. ; 6:1, s. 96-118
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Tidskriftsartikel (refereegranskat)abstract
- Talreja and coworkers have reported brittle and tough polymer matrix composites to show different cross-ply laminate stiffness reductions due to transverse cracks, despite very similar elastic properties. Studies of crack opening displacement (COD) in [0,,,90,] laminates may help in solution of this problem. Approximate analytical models based on the variational approach pioneered by Hashin were therefore applied in addition to FEM-calculations. Approximate models were concluded not to be reliable for future analyses of this problem. Experimental COD for brittle GF/EP laminates at low crack densities was fairly well predicted by FEM-calculations. None of the models were able to predict experimental data at high crack densities. Residual plastic strains are suggested as an explanation and may also be responsible for reported matrix-related differences in stiffness reduction.
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| 4. |
- Andersson, B., et al.
(författare)
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Micro- and meso-level residual stresses in glass-fiber/vinyl-ester composites
- 2000
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Ingår i: Composites Science And Technology. - : Elsevier Science Ltd, Exeter, United Kingdom. - 0266-3538 .- 1879-1050. ; 60:10, s. 2011-2028
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Tidskriftsartikel (refereegranskat)abstract
- Residual stresses in glass-fiber composites were studied on the micro and meso scales by computational and experimental methods. Transmitted polarized light images of thin sections were compared with 3D finite-element solutions of a sample containing 1410 fibers. Calculated point-wise stresses were derived from a linear thermoelastic model with negligibly small numerical errors. Regions with calculated maximum compressive stresses showed good agreement with experimentally observed optical bands. A material with poor interfacial adhesion showed weaker optical effects indicating fiber/matrix debonding. On the basis of these results it stems likely that irreversible matrix deformation and debonding can take place in the curing phase.
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| 5. |
- Asp, Leif, et al.
(författare)
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Prediction of failure initiation in polypropylene with glass beads
- 1997
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Ingår i: Polymer Composites. - : Wiley. - 0272-8397 .- 1548-0569. ; 18:1, s. 9-15
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Tidskriftsartikel (refereegranskat)abstract
- The effect of glass bead content and residual stresses on failure initiation in isotactic polypropylene composites has been investigated by finite element analysis for the cases of interfacial debonding, plastic yielding, and cavitation. Residual thermal stresses are demonstrated to have a large effect on global failure initiation stress. Yielding and cavitation occur at higher global stresses than debonding. Modeling results, as well as previous experimental data, support debonding as the initial failure mechanism
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| 6. |
- Ecke, Frauke, et al.
(författare)
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Spatio-temporal variation of metals and organic contaminants in bank voles (Myodes glareolus)
- 2020
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 713
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Tidskriftsartikel (refereegranskat)abstract
- Environmental contamination with metals and organic compounds is of increasing concern for ecosystem and human health. Still, our knowledge about spatial distribution, temporal changes and ecotoxicological fate of metals and organic contaminants in wildlife is limited. We studied concentrations of 69 elements and 50 organic compounds in 300 bank voles (Myodes glareolus), Europe's most common mammal, sampled in spring and autumn 2017–2018 in five monitoring areas, representing three biogeographic regions. In addition, we compared measured concentrations with previous results from bank voles sampled within the same areas in 1995–1997 and 2001. In general, our results show regional differences, but no consistent patterns among contaminants and study areas. The exception was for the lowest concentrations of organic contaminants (e.g. perfluorooctane sulfonate, PFOS), which were generally found in the northern Swedish mountain area. Concentrations of metals and organic contaminants in adults varied seasonally with most organic contaminants being higher in spring; likely induced by diet shifts but potentially also related to age differences. In addition, metal concentrations varied between organs (liver vs. kidney), age classes (juveniles vs. adults; generally higher in adults) as well as between males and females. Concentrations of chromium and nickel in kidney and liver in the northernmost mountain area were lower in 2017–2018 than in 1995–1997 and in three of four areas, lead concentrations were lower in 2017–2018 than in 2001. Current metal concentrations (except mercury) are not expected to negatively affect the voles. Concentrations of hexachlorobenzene displayed highest concentrations in 2001 in the mountains, while it was close to detection limit in 2017–2018. Likewise, PFOS concentrations decreased in the mountains and in south-central lowland forests between 2001 and 2017–2018. Our results suggest that season, age class and sex need to be considered when designing and interpreting results from monitoring programs targeting inorganic and organic contaminants in wildlife.
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| 7. |
- Falcon, Javier A., et al.
(författare)
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In situ monitoring of antisolvent addition crystallization with principal components analysis of Raman spectra
- 2004
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 4:3, s. 457-463
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Tidskriftsartikel (refereegranskat)abstract
- Fiber optic Raman spectroscopy was used for in situ monitoring of antisolvent addition crystallization of progesterone. Raman spectral features of the solute and the antisolvent were subjected to principal components analysis (PCA) to attempt to obtain information that is not readily apparent from the raw spectral data. For the system utilized, PCA was able to distinguish spectral features from the solute in solution, the solute crystals, and the antisolvent. Furthermore, PCA was capable of detecting subtle changes in the spectral data (as the addition of antisolvent progressed) that could be used as a warning for the onset of crystallization. The current study demonstrates the advantages that can be gained by combining PCA with Raman spectroscopy for monitoring crystallizations in situ.
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| 8. |
- Glassner, David A., et al.
(författare)
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Purification process for succinic acid produced by fermentation
- 1995
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Ingår i: Applied Biochemistry and Biotechnology. - 0273-2289 .- 1559-0291. ; 51-52:1, s. 73-82
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Tidskriftsartikel (refereegranskat)abstract
- Succinic acid is a versatile four-carbon dicarboxylic acid. It can be used commerically as an intermediate chemical for the manufacture of 1,4-butanediol, maleic anhydride, and many other chemicals. Succinic acid can be produced by the fermentation of carbohydrates. A complete process for the production and purification of succinic acid from carbohydrates has been developed. The process includes fermentation, desalting electrodialysis, water-splitting electrodialysis, and crystallization to produce a pure crystalline succinic acid. This article will present experimental work performed in the development of this process.
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| 9. |
- Holmberg, J.A., et al.
(författare)
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Manufacturing and performance of RTM U-beams
- 1997
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Ingår i: Composites. Part A, Applied science and manufacturing. - 1359-835X .- 1878-5840. ; 28:6, s. 513-521
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Tidskriftsartikel (refereegranskat)abstract
- Geometrical limitations and robustness of resin transfer moulding were investigated for single curved laminates. The design of experiments approach was used to determine how the out of plane tensile strength is affected by variations in performing method, radius, fibre content and vacuum assistance. U-beams with an inner radius of 0.8 mm were manufactured and demonstrated good mechanical performance. The strength of these beams was in fact less sensitive to defects than the strength of beams with a 5 mm radius. Different preforming methods can have a strong influence on beam strength due to effects on the void content in the finished laminates. The particular preforming problems encountered are described and possible solutions are suggested and tested. For example utilisation of vacuum assistance during mould filling reduces void content, which in turn tends to reduce the sensitivity of the beam strength to other defects such as wrinkling.
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| 10. |
- Holmberg, J.A., et al.
(författare)
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Micromechanisms of delamination failure in RTM U-beams
- 1997
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Ingår i: Composites. Part A, Applied science and manufacturing. - 1359-835X .- 1878-5840. ; 28:8, s. 709-717
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Tidskriftsartikel (refereegranskat)abstract
- In a previous study, resin transfer moulded U-beams were subjected to opening tensile loads applied to the flanges. The failure behaviour was sensitive to the void content of the material. In the present study, we use optical microscopy of polished edges to observe mechanisms of failure in-situ as delaminations develop in the beam radius. Descriptions of these failure mechanisms are presented. Voids were found to facilitate the growth phase of the delamination process in the beam radius. The mechanisms described will be used in a forthcoming stress analysis to explain the experimentally observed failure behaviour of beams with different radii and void contents.
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