| 1. |
- Zhang, Shuangshuang, et al.
(författare)
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Narrow-gap, semiconducting, superhard amorphous carbon with high toughness, derived from C60 fullerene
- 2021
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Ingår i: Cell Reports Physical Science. - : Elsevier. - 2666-3864. ; 2:9
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Tidskriftsartikel (refereegranskat)abstract
- New carbon forms that exhibit extraordinary physicochemical properties can be generated from nanostructured precursors under extreme pressure. Nevertheless, synthesis of such fascinating materials is often not well understood. That is the case of the C60 precursor, with irreproducible results that impede further progress in the materials design. Here, the semiconducting amorphous carbon, having band gaps of 0.1–0.3 eV and the advantages of isotropic superhardness and superior toughness over single-crystal diamond and inorganic glasses, is produced from fullerene at high pressure and moderate temperatures. A systematic investigation of the structure and bonding evolution is carried out with complementary characterization methods, which helps to build a model of the transformation that can be used in further high-pressure/high-temperature (high p,T) synthesis of novel nano-carbon systems for advanced applications. The amorphous carbon materials produced have the potential of accomplishing the demanding optoelectronic applications that diamond and graphene cannot achieve.
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| 2. |
- Abdelaziz, Omar Y., et al.
(författare)
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Recent strides toward transforming lignin into plastics and aqueous electrolytes for flow batteries
- 2024
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Ingår i: iScience. - : Elsevier Inc.. - 2589-0042. ; 27:4
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Forskningsöversikt (refereegranskat)abstract
- Lignin is an abundant polyaromatic polymer with a wide range of potential future uses. However, the conversion of lignin into valuable products comes at a cost, and medium- to high-value applications are thus appropriate. Two examples of these are polymers (e.g., as fibers, plasticizers, or additives) and flow batteries (e.g., as redox species). Both of these areas would benefit from lignin-derived molecules with potentially low molecular weight and high (electro)chemical functionality. A promising route to obtain these molecules is oxidative lignin depolymerization, as it enables the formation of targeted compounds with multiple functionalities. An application with high potential in the production of plastics is the synthesis of new sustainable polymers. Employing organic molecules, such as quinones and heterocycles, would constitute an important step toward the sustainability of aqueous flow batteries, and lignin and its derivatives are emerging as redox species, mainly due to their low cost and renewability.
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| 3. |
- Antfolk, Christian, et al.
(författare)
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Exploring the conditions for PhD-students to develop abilities to independently formulate research questions
- 2015
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Rapport (populärvet., debatt m.m.)abstract
- Developing an ability to independently formulate research questions is an important goal in doctoral education. During a seminar in the “Docent course”, accredited by Genombrottet at Lund University, the authors behind this paper ended up in a discussion on the actual conditions for developing such ability. During the discussions, the authors, based on their own experiences, identified several conditions that could hamper the PhD-students’ abilities to develop the skills required to independently formulate research questions. Examples of such conditions were: involvement in projects where objectives and deliverables already were stated by a funder, a lack of discussions with supervisors early in the PhD-process, and/or a lack of proper training. The authors also discussed if working with a compilation thesis automatically lead to contrived overall research questions, which resulted primarily as an afterthought at a very late stage in the process.
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| 4. |
- Aristizábal-Lanza, Lucía, et al.
(författare)
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Comparison of the enzymatic depolymerization of polyethylene terephthalate and AkestraTM using Humicola insolens cutinase
- 2022
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Ingår i: Frontiers in Chemical Engineering. - : Frontiers Media SA. - 2673-2718. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- The enzymatic depolymerization of synthetic polyesters has become of great interest in recycling plastics. Most of the research in this area focuses on the depolymerization of polyethylene terephthalate (PET) due to its widespread use in various applications. However, the enzymatic activity on other commercial polyesters is less frequently investigated. Therefore, AkestraTM attracted our attention, which is a copolymer derived from PET with a partially biobased spirocyclic acetal structure. In this study, the activity of Humicola insolens cutinase (HiCut) on PET and AkestraTM films and powder was investigated. HiCut showed higher depolymerization activity on amorphous PET films than on Akestra™ films. However, an outstanding performance was achieved on AkestraTM powder, reaching 38% depolymerization in 235h, while only 12% for PET powder. These results are consistent with the dependence of the enzymes on the crystallinity of the polymer since Akestra™ is amorphous while the PET powder has 14% crystallinity. On the other hand, HiCut docking studies and molecular dynamic simulations (MD) suggested that the PET-derived mono (hydroxyethyl)terephthalate dimer (MHET)2 is a hydrolyzable ligand, producing terephthalic acid (TPA), while the Akestra™-derived TPA-spiroglycol ester is not, which is consistent with the depolymerization products determined experimentally. MD studies also suggest ligand-induced local conformational changes in the active site.
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| 5. |
- Arza, Carlos R., et al.
(författare)
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Biocompatible non-leachable antimicrobial polymers with a nonionic hyperbranched backbone and phenolic terminal units
- 2022
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Ingår i: Journal of Materials Chemistry B. - : Royal Society of Chemistry (RSC). - 2050-750X .- 2050-7518. ; 10:39, s. 8064-8074
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Tidskriftsartikel (refereegranskat)abstract
- This work aimed to develop biocompatible non-leachable antimicrobial polymers without ionic structures. A series of nonionic hyperbranched polymers (HBPs) with an isatin-based backbone and phenolic terminal units were synthesized and characterized. The molecular structures and thermal properties of the obtained HBPs were characterized by SEC, NMR, FTIR, TGA and DSC analyses. Disk diffusion assay revealed significant antibacterial activity of the obtained phenolic HBPs against nine different pathogenic bacteria. The presence of a methoxy or long alkyl group close to the phenolic unit enhanced the antibacterial effect against certain Gram positive and negative bacteria. The obtained nonionic HBPs were blended in polyester poly(hexamethylene terephthalate) films, which showed no noticeable leakage after being immersed in water for 5 days. Finally, these HBPs showed no cytotoxicity effect to MG-63 osteoblast-like human cells according to MTT analysis, and negligible hemolytic effect.
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| 6. |
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| 7. |
- Arza, Carlos R., et al.
(författare)
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Synthesis, Thermal Properties, and Rheological Characteristics of Indole-Based Aromatic Polyesters
- 2019
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:12, s. 15012-15021
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Tidskriftsartikel (refereegranskat)abstract
- Currently, there is an intensive development of bio-based aromatic building blocks to replace fossil-based terephthalates used for poly(ethylene terephthalate) production. Indole is a ubiquitous aromatic unit in nature, which has great potential as a bio-based feedstock for polymers or plastics. In this study, we describe the synthesis and characterization of new indole-based dicarboxylate monomers with only aromatic ester bonds, which can improve the thermal stability and glass-transition temperature (Tg) of the resulting polyesters. The new dicarboxylate monomers were polymerized with five aliphatic diols to yield 10 new polyesters with tunable chemical structures and physical properties. Particularly, the Tg values of the obtained polyesters can be as high as 113 °C, as indicated by differential scanning calorimetry and dynamic mechanical analysis. The polyesters showed decent thermal stability and distinct flow transitions as revealed by thermogravimetric analysis and rheology measurements.
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| 8. |
- Bertran, Oscar, et al.
(författare)
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Modeling Nanosized Single Molecule Objects: Dendronized Polymers Adsorbed onto Mica
- 2015
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 119:7, s. 3746-3753
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Tidskriftsartikel (refereegranskat)abstract
- We attempt to provide direct evidence for the suggested behavior of dendronized polymers as molecular objects (i.e., single shape persistent macromolecules). For this purpose, the microscopic structure of dendronized polymers adsorbed onto mica has been investigated using atomistic molecular dynamics simulations. We find that the shape of the second to fourth generation dendronized polymers is basically kept upon adsorption due to substantial backfolding within their interior. The fluctuation strength of the polymer backbones, which is seen to decrease with increasing generation, also indicates that these individual macromolecules exhibit molecular object behavior in the nanosize range.
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| 9. |
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| 10. |
- Demircan, Deniz, et al.
(författare)
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Facile synthesis of novel soluble cellulose-grafted hyperbranched polymers as potential natural antimicrobial materials
- 2017
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 157, s. 1913-1921
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Tidskriftsartikel (refereegranskat)abstract
- A new class of soluble cellulose-grafted hyperbranched polymers has been synthesized by a facile “hypergrafting” reaction using bis(2-chloroethyl)amine and soluble cellulose tosylates. The molecular structures of the obtained new materials were characterized by 13C NMR, FTIR spectroscopy, and elemental analysis. The degree of substitution of the hyperbranched cellulose derivatives ranges between 0.13–0.53. The new cellulose-based materials were soluble in various polar aprotic organic solvents. The thermal properties of the new cellulose materials were investigated by thermal gravimetric analysis. Antibacterial activity of the new cellulose derivatives was evaluated by diffusion disk tests against various gram negative and positive bacteria. Our results suggested that the obtained natural cellulosic materials can act as effective polymeric biocides, and may have great potential in various antimicrobial materials applications.
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