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| 2. |
- Balakshin, Mikhail, et al.
(författare)
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Spruce milled wood lignin : Linear, branched or cross-linked?
- 2020
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Ingår i: Green Chemistry. - : Royal Society of Chemistry. - 1463-9262 .- 1463-9270. ; 22:13, s. 3985-4001
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Tidskriftsartikel (refereegranskat)abstract
- The subject of lignin structure, critical for fundamental and practical reasons, is addressed in this study that includes a review of the methods applied to elucidate macromolecular branching. The recently available approaches for determination of the absolute molecular mass of spruce milled wood lignin (MWL) along with the quantification of terminal groups clearly indicate that MWL is significantly branched and cross-linked (with ∼36% lignin units partaking in these linkages). Results from independent methods imply that about half of the branching and crosslinking linkages involve aromatic rings, predominantly 5-5′ etherified units; meanwhile, a significant number of linkages are located in the side chains. Quantitative 13C NMR analyses suggest that the branches involve different aliphatic ether (alkyl-O-alkyl) types at the α- and γ-positions of the side chain, with intact β-O-4 linkages. While the exact structures of these moieties require further investigation, our results point to the fact that conventional lignification theory disagrees with the presence of such key moieties in softwood MWL and the observed high degree of branching/crosslinking. Potential reasons for the noted discrepancies are discussed.
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| 3. |
- Balakshin, Mikhail Yu, et al.
(författare)
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New Opportunities in the Valorization of Technical Lignins.
- 2021
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 14:4, s. 1016-1036
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Tidskriftsartikel (refereegranskat)abstract
- Sugar-based biorefineries have faced significant economic challenges. Biorefinery lignins are often classified as low-value products (fuel or low-cost chemical feedstock) mainly due to low lignin purities in the crude material. However, recent research has shown that biorefinery lignins have a great chance of being successfully used as high-value products, which in turn should result in an economy renaissance of the whole biorefinery idea. This critical review summarizes recent developments from our groups, along with the state-of-the-art in the valorization of technical lignins, with the focus on biorefinery lignins. A beneficial synergistic effect of lignin and cellulose mixtures used in different applications (wood adhesives, carbon fiber and nanofibers, thermoplastics) has been demonstrated. This phenomenon causes crude biorefinery lignins, which contain a significant amount of residual crystalline cellulose, to perform superior to high-purity lignins in certain applications. Where previously specific applications required high-purity and/or functionalized lignins with narrow molecular weight distributions, simple green processes for upgrading crude biorefinery lignin are suggested here as an alternative. These approaches can be easily combined with lignin micro-/nanoparticles (LMNP) production. The processes should also be cost-efficient compared to traditional lignin modifications. Biorefinery processes allow much greater flexibility in optimizing the lignin characteristics desirable for specific applications than traditional pulping processes. Such lignin engineering, at the same time, requires an efficient strategy capable of handling large datasets to find correlations between process variables, lignin structures and properties and finally their performance in different applications.
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| 4. |
- Koso, Tetyana, et al.
(författare)
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2D Assignment and quantitative analysis of cellulose and oxidized celluloses using solution-state NMR spectroscopy
- 2020
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 27:14, s. 7929-7953
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Tidskriftsartikel (refereegranskat)abstract
- The limited access to fast and facile general analytical methods for cellulosic and/or biocomposite materials currently stands as one of the main barriers for the progress of these disciplines. To that end, a diverse set of narrow analytical techniques are typically employed that often are time-consuming, costly, and/or not necessarily available on a daily basis for practitioners. Herein, we rigorously demonstrate a general quantitative NMR spectroscopic method for structural determination of crystalline cellulose samples. Our method relies on the use of a readily accessible ionic liquid electrolyte, tetrabutylphosphonium acetate ([P-4444][OAc]):DMSO-d(6), for the direct dissolution of biopolymeric samples. We utilize a series of model compounds and apply now classical (nitroxyl-radical and periodate) oxidation reactions to cellulose samples, to allow for accurate resonance assignment, using 2D NMR. Quantitative heteronuclear single quantum correlation (HSQC) was applied in the analysis of key samples to assess its applicability as a high-resolution technique for following cellulose surface modification. Quantitation using HSQC was possible, but only after applying T(2)correction to integral values. The comprehensive signal assignment of the diverse set of cellulosic species in this study constitutes a blueprint for the direct quantitative structural elucidation of crystalline lignocellulosic, in general, readily available solution-state NMR spectroscopy. [GRAPHICS] .
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| 5. |
- Liu, Jun, et al.
(författare)
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Potentially Immunogenic Contaminants in Wood-Based and Bacterial Nanocellulose : Assessment of Endotoxin and (1,3)-β-d-Glucan Levels
- 2018
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 19:1, s. 150-157
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge gaps in the biosafety data of the nanocellulose (NC) for biomedical use through various routes of administration call for closer look at health and exposure evaluation. This work evaluated the potentially immunogenic contaminants levels, for example, endotoxin and (1,3)-β-d-glucan, in four representative NCs, that is, wood-based NCs and bacterial cellulose (BC). The hot-water extracts were analyzed with ELISA assays, HPSEC-MALLS, GC, and NMR analysis. Varying levels of endotoxin and (1,3)-β-d-glucan contaminats were found in these widely used NCs. Although the β-(1,3)-d-glucan was not detected from the NMR spectra due to the small extract samples amount (2–7 mg), the anomerics and highly diastereotopic 6-CH2 signals may suggest the presence of β-(1,4)-linkages with β-(1,6) branching in the polysaccharides of NCs’ hot-water extracts, which were otherwise not detectable in the enzymatic assay. In all, the article highlights the importance of monitoring various water-soluble potentially immunogenic contaminants in NC for biomedical use.
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| 7. |
- Rice, Thomas, et al.
(författare)
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Revisiting out-of-pocket requirements : Trends in spending, financial access barriers, and policy in ten high-income countries
- 2018
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Ingår i: BMC Health Services Research. - : Springer Science and Business Media LLC. - 1472-6963. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Countries rely on out-of-pocket (OOP) spending to different degrees and employ varying techniques. The article examines trends in OOP spending in ten high-income countries since 2000, and analyzes their relationship to self-assessed barriers to accessing health care services. The countries are Australia, Canada, France, Germany, the Netherlands, New Zealand, Norway, Sweden, Switzerland, the United Kingdom, and the United States. Methods: Data from three sources are employed: OECD statistics, the Commonwealth Fund survey of individuals in each of ten countries, and country-specific documents on health care policies. Based on trends in OOP spending, we divide the ten countries into three groups and analyze both trends and access barriers accordingly. As part of this effort, we propose a conceptual model for understanding the key components of OOP spending. Results: There is a great deal of variation in aggregate OOP spending per capita spending but there has been convergence over time, with the lowest-spending countries continuing to show growth and the highest spending countries showing stability. Both the level of aggregate OOP spending and changes in spending affect perceived access barriers, although there is not a perfect correspondence between the two. Conclusions: There is a need for better understanding the root causes of OOP spending. This will require data collection that is broken down into OOP resulting from cost sharing and OOP resulting from direct payments (due to underinsurance and lacking benefits). Moreover, data should be disaggregated by consumer groups (e.g. income-level or health status). Only then can we better link the data to specific policies and suggest effective solutions to policy makers.
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