| 1. |
- Barea-Sepulveda, Marta, et al.
(author)
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Total Ion Chromatogram and Total Ion Mass Spectrum as Alternative Tools for Detection and Discrimination (A Review)
- 2022
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In: CHEMOSENSORS. - : MDPI AG. - 2227-9040. ; 10:11
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Research review (peer-reviewed)abstract
- Gas chromatography (GC) and mass spectrometry (MS) are widely used techniques in the analysis of complex mixtures due to their various advantages, such as high selectivity, reproducibility, precision, and sensitivity. However, the data processing is often complex and time-consuming and requires a great deal of experience, which might be a serious drawback in certain areas, such as quality control, or regarding research in the field of medicine or forensic sciences, where time plays a crucial role. For these reasons, some authors have proposed the use of alternative data processing approaches, such as the total ion chromatogram or total mass spectrum, allowing these techniques to be treated as sensors where each retention time or ratio m/z acts as a sensor collecting total intensities. In this way, the main advantages associated with both techniques are maintained, but the outcomes from the analysis can be reached in a faster, simpler, and an almost automated way. In this review, the main features of the GC- and MS-based analysis methodologies and the ways in which to apply them are highlighted. Moreover, their implementation in different fields, such as agri-food, forensics, environmental sciences, or medicine is discussed, highlighting important advantages as well as limitations.
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| 2. |
- Gubitosi, Marta, et al.
(author)
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On cellulose dissolution and aggregation in aqueous tetrabutylammonium hydroxide
- 2016
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In: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 17:9, s. 2873-2881
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Journal article (peer-reviewed)abstract
- Aqueous tetrabutylammonium hydroxide, TBAH(aq), has been found to dissolve cellulose and to be a potential solvent for chemical processing or fiber spinning. In this paper, we have investigated the dissolution state of cellulose in 40 wt % TBAH(aq) solvent, and present an extensive study of rheology, combined with static light and small-angle X-ray scattering, to correlate cellulose aggregation with changes in the rheological parameters. Two cellulose molecular weights are compared. Microcrystalline cellulose (MCC), with a degree of polymerization of ca. 260, and a dissolving pulp with an approximately ten times higher molecular weight. Scattering data demonstrate that cellulose is molecularly dissolved at lower cellulose concentrations, while aggregates are present when the concentration exceeds a certain value. The onset of the aggregate formation is marked by a pronounced increase in the scattering intensity at low q, shear thinning behavior and violation of the empirical Cox-Merz rule. Additionally, the SAXS data suggest the presence of a solvation shell enriched in TBA+ ions, compared to the bulk solvent. The results are consistent with the recent suggestion that while native cellulose I may still dissolve, solutions are, above a particular concentration, becoming supersaturated with respect to the more stable crystal form cellulose II.
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| 3. |
- Kattge, Jens, et al.
(author)
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TRY plant trait database - enhanced coverage and open access
- 2020
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In: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Journal article (peer-reviewed)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 4. |
- Medronho, Bruno, et al.
(author)
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Probing cellulose amphiphilicity
- 2015
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In: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 30:1, s. 58-66
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Journal article (peer-reviewed)abstract
- Cellulose dissolution and regeneration is an increasingly active research field due to the direct relevance for numerous production processes and applications. The problem is not trivial since cellulose solvents are of remarkably different nature and thus the understanding of the subtle balance between the different interactions involved becomes difficult but crucial. There is a current discussion in literature on the balance between hydrogen bonding and hydrophobic interactions in controlling the solution behavior of cellulose. This treatise attempts to review recent work highlighting the marked amphiphilic characteristics of cellulose and role of hydrophobic interactions in dissolution and regeneration. Additionally, a few examples of our own research are discussed focusing on the role of different additives in cellulose solubility. The data does support the amphiphilic behavior of cellulose, which clearly should not be neglected when developing new solvents and strategies for cellulose dissolution and regeneration.
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| 5. |
- Pereira, Ana, et al.
(author)
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Cellulose gelation in NaOH solutions is due to cellulose crystallization
- 2018
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In: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 25:6, s. 3205-3210
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Journal article (peer-reviewed)abstract
- Abstract: Cellulose gelation in 2 M NaOH aqueous solution was followed by time resolved turbidity and rheology measurements. The kinetics of gelation is observed to change from several hours down to few seconds when the temperature is increased from 25 to 30 °C. The increase of turbidity upon gelation demonstrates the formation of larger cellulose aggregates, while wide angle X-ray scattering data confirms the gradual formation of crystalline domains. This suggests that the gelation can be understood as cellulose precipitation/crystallization where an effectively cross linked network and gelation results from that cellulose chains may participate in more than one crystallite. Graphical Abstract: The gelation of cellulose solutions is due to crystallization and precipitation of cellulose.[Figure not available: see fulltext.]
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