14 results on '"Sommertune, J"'
Search Results
2. Carbon Fibers from Lignin-Cellulose Precursors : Effect of Carbonization Conditions
- Author
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Bengtsson, Andreas, Hecht, P., Sommertune, J., Ek, Monica, Sedin, M., Sjöholm, E., Bengtsson, Andreas, Hecht, P., Sommertune, J., Ek, Monica, Sedin, M., and Sjöholm, E.
- Abstract
Carbon fibers (CFs) are gaining increasing importance in lightweight composites, but their high price and reliance on fossil-based raw materials stress the need for renewable and cost-efficient alternatives. Kraft lignin and cellulose are renewable macromolecules available in high quantities, making them interesting candidates for CF production. Dry-jet wet spun precursor fibers (PFs) from a 70/30 w/w blend of softwood kraft lignin (SKL) and fully bleached softwood kraft pulp (KP) were converted into CFs under fixation. The focus was to investigate the effect of carbonization temperature and time on the CF structure and properties. Reducing the carbonization time from 708 to 24 min had no significant impact on the tensile properties. Increasing the carbonization temperature from 600 to 800 °C resulted in a large increase in the carbon content and tensile properties, suggesting that this is a critical region during carbonization of SKL:KP PFs. The highest Young's modulus (77 GPa) was obtained after carbonization at 1600 °C, explained by the gradual transition from amorphous to nanocrystalline graphite observed by Raman spectroscopy. On the other hand, the highest tensile strength (1050 MPa) was achieved at 1000 °C, a decrease being observed thereafter, which may be explained by an increase in radial heterogeneity., QC 20200611 more...
- Published
- 2020
- Full Text
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Catalog
3. The impact of N,N-dimethyldodecylamine N-oxide (DDAO) concentration on the crystallisation of sodium dodecyl sulfate (SDS) systems and the resulting changes to viscosity, crystal structure, shape and the kinetics of crystal growth
- Author
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Summerton, E, Hollamby, M, Zimbitas, G, Snow, T, Smith, A, Sommertune, J, Bettiol, J, Jones, C, Britton, M, and Bakalis, S
- Subjects
QD ,TP155 - Abstract
Hypothesis\ud At low temperatures stability issues arise in commercial detergent products when surfactant crystallisation occurs, a process which is not currently well-understood. An understanding of the phase transition can be obtained using a simple binary SDS (sodium dodecyl sulfate) + DDAO (N,N-dimethyldodecylamine N-oxide) aqueous system. It expected that the crystallisation temperature of an SDS system can be lowered with addition of DDAO, thus providing a route to improve detergent stability.\ud \ud Experiments\ud Detergent systems are typically comprised of anionic surfactants, non-ionic surfactants and water. This study explores the crystallisation of a three component system consisting of sodium dodecyl sulfate (SDS), N,N–dimethyldodecylamine N-oxide (DDAO), and water using wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC) and confocal Raman microscopy.\ud \ud Findings\ud The presence of DDAO lowered the crystallisation temperature of a 20 wt% SDS system. For all aqueous mixtures of SDS + DDAO at low temperatures, SDS hydrated crystals, SDS.1/2H2O or SDS·H2O, formed. SDS hydrates comprising of layers of SDS separated by water layers. DDAO tended to reside in the vicinity of these SDS crystals. In the absence of DDAO an additional intermediary hydrate structure, SDS.1/8H2O, formed whereas for mixed SDS + DDAO systems no such structure was detected during crystallisation. more...
- Published
- 2018
4. Standardization methods for the synthesis of single-core and multi-core magnetic nanoparticles for medical applications
- Author
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Gavilán, Helena, Costo, Rocío, Heinke, D., Sugunan, A., Sommertune, J., Fornara, A., Gehrke, N., Grüttner, C., Westphal, F., Veintemillas-Verdaguer, S., Johansson, and Morales, M. P.
- Abstract
Oral presentation given at the International Magnetics Conference (INTERMAG Europe 2017), held in Dublin (Ireland) on April 24-28th, 2017., The number of biomedical applications using colloidal magnetic iron oxide nanoparticles has been increasing exponentially over the past few years [1]. Several approaches exist to obtain single-core and multi-core particles but the production of particles with good control of the number of magnetic cores per particle, and the degree of polydispersity of both, particle and core sizes is still a difficult task [2-5]. In addition, the magnetic properties of the nanoparticles may change significantly depending on their aggregation degree (and further agglomeration), which depends to a large extent on the synthesis method [6]. The complexity of the problem of understanding the different magnetic properties of single-core and multi-core nanoparticles underlies the importance of reliable synthesis methods able to reproduce nanoparticle size, shape and structural homogeneity. Here, we present different synthesis strategies in organic, polyol and aqueous media for colloidal single-core and multi-core iron oxide nanoparticles for biomedical applications (Fig. 1). We explore the factors determining the monodispersity in terms of size and shape and the core assembly, and discuss their implication on the resulting structural, colloidal and magnetic properties. We will show that reliable and reproducible analysis methods are also needed to characterize the different magnetic particle systems [7]. For example, in order to compare size parameters precisely determined from different methods and models, it is crucial to establish standardized analysis methods and models to extract reliable parameters from the data, which are necessary both for defining magnetic nanoparticle systems and for quality control during the synthesis of magnetic nanoparticles. Many parameters of the synthesis procedure may have a strong effect on the particles obtained, including temperature, reaction time, reagent concentrations, and stirring conditions. This is one of the reasons why scaling-up of some of these synthesis routes is extremely complicated. Indeed, one of the difficulties that particle synthesis faces is batch-to batch reproducibility. Other important difficulty is the fundamental and pressing need to develop more sustainable protocols, using less toxic reagents in a more efficacious manner. more...
- Published
- 2017
5. Structural and magnetic properties of multi-core nanoparticles analysed using a generalised numerical inversion method
- Author
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Bender, P., primary, Bogart, L. K., additional, Posth, O., additional, Szczerba, W., additional, Rogers, S. E., additional, Castro, A., additional, Nilsson, L., additional, Zeng, L. J., additional, Sugunan, A., additional, Sommertune, J., additional, Fornara, A., additional, González-Alonso, D., additional, Barquín, L. Fernández, additional, and Johansson, C., additional more...
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- 2017
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6. Utilization of bis-MPA Dendrimers for the Calibration of Ion Mobility Collision Cross Section Calculations.
- Author
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Sekera ER, Somogyi Á, Takáts Z, Stappert F, Thom C, Schmitz OJ, Moeckel C, Paizs B, and Sommertune J
- Abstract
Ion mobility-mass spectrometry (IM-MS) has become increasingly popular with the rapid expansion of available techniques and instrumentation. To enable accuracy, standardization, and repeatability of IM-MS measurements, the community requires reliable and well-defined reference materials for calibration and tuning of the equipment. To address this need, synthetic dendrimers of high chemical and structural purity were tested on three ion mobility platforms as potential calibrants. First, synthesized dendrimers were characterized by drift tube ion mobility (DTIMS), using an Agilent 6560 IM-qTOF-MS to assess their drift tube collision cross section (
DT CCS) values. Then, assessment of obtained CCS values on trapped ion mobility (TIMS) and traveling wave ion mobility (TWIMS) ion mobility platforms were compared to those found by DTIMS. Across all three systems, dendrimers were found to have high potential for m / z and ion mobility calibration in the CCS range of 160-1700 Å2 . To further validate their use as calibrants, drift tube calculated CCS values for dendrimers were utilized to calibrate calculations of CCS for known standards including Agilent Tuning mix, the CCS Major mix from Waters, and SPLASH LIPIDOMIX. Additionally, structures of sodiated dendrimers were computated along with theoretical CCS values which showed good agreement with the experimental CCS values. On the basis of the results presented, we recommend the use of dendrimers as alternatives and/or complementary compounds to commonly used calibrants for ion mobility platforms. more...- Published
- 2024
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7. SERS Hotspot Engineering by Aerosol Self-Assembly of Plasmonic Ag Nanoaggregates with Tunable Interparticle Distance.
- Author
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Li H, Merkl P, Sommertune J, Thersleff T, and Sotiriou GA
- Subjects
- Aerosols, Reproducibility of Results, Silver chemistry, Spectrum Analysis, Raman methods, Metal Nanoparticles chemistry
- Abstract
Surface-enhanced Raman scattering (SERS) is a powerful sensing technique. However, the employment of SERS sensors in practical applications is hindered by high fabrication costs from processes with limited scalability, poor batch-to-batch reproducibility, substrate stability, and uniformity. Here, highly scalable and reproducible flame aerosol technology is employed to rapidly self-assemble uniform SERS sensing films. Plasmonic Ag nanoparticles are deposited on substrates as nanoaggregates with fine control of their interparticle distance. The interparticle distance is tuned by adding a dielectric spacer during nanoparticle synthesis that separates the individual Ag nanoparticles within each nanoaggregate. The dielectric spacer thickness dictates the plasmonic coupling extinction of the deposited nanoaggregates and finely tunes the Raman hotspots. By systematically studying the optical and morphological properties of the developed SERS surfaces, structure-performance relationships are established and the optimal hot-spots occur for interparticle distance of 1 to 1.5 nm among the individual Ag nanoparticles, as also validated by computational modeling, are identified for the highest signal enhancement of a molecular Raman reporter. Finally, the superior stability and batch-to-batch reproducibility of the developed SERS sensors are demonstrated and their potential with a proof-of-concept practical application in food-safety diagnostics for pesticide detection on fruit surfaces is explored., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.) more...
- Published
- 2022
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8. The role of water in the reversibility of thermal denaturation of lysozyme in solid and liquid states.
- Author
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Phan-Xuan T, Bogdanova E, Sommertune J, Fureby AM, Fransson J, Terry AE, and Kocherbitov V
- Abstract
Although unfolding of protein in the liquid state is relatively well studied, its mechanisms in the solid state, are much less understood. We evaluated the reversibility of thermal unfolding of lysozyme with respect to the water content using a combination of thermodynamic and structural techniques such as differential scanning calorimetry, synchrotron small and wide-angle X-ray scattering (SWAXS) and Raman spectroscopy. Analysis of the endothermic thermal transition obtained by DSC scans showed three distinct unfolding behaviors at different water contents. Using SWAXS and Raman spectroscopy, we investigated reversibility of the unfolding for each hydration regime for various structural levels including overall molecular shape, secondary structure, hydrophobic and hydrogen bonding interactions. In the substantially dehydrated state below 37 wt% of water the unfolding is an irreversible process and can be described by a kinetic approach; above 60 wt% the process is reversible, and the thermodynamic equilibrium approach is applied. In the intermediate range of water contents between 37 wt% and 60 wt%, the system is phase separated and the thermal denaturation involves two processes: melting of protein crystals and unfolding of protein molecules. A phase diagram of thermal unfolding/denaturation in lysozyme - water system was constructed based on the experimental data., Competing Interests: We declare no conflict of interest., (© 2021 The Authors.) more...
- Published
- 2021
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9. Release of carbon nanotubes during combustion of polymer nanocomposites in a pilot-scale facility for waste incineration.
- Author
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Janhäll S, Petersson M, Davidsson K, Öman T, Sommertune J, Kåredal M, Messing ME, and Rissler J
- Subjects
- Carbonates, Coal Ash analysis, Incineration, Polyethylene analysis, Polymers, Nanocomposites, Nanotubes, Carbon
- Abstract
Nanocomposites, formed by incorporating nanoparticles into a matrix of standard materials, are increasing on the market. Little focus has been directed towards safe disposal and recycling of these new materials even though the disposal has been identified as a phase of the products' life cycle with a high risk of uncontrolled emissions of nanomaterials. In this study, we investigate if the carbon nanotubes (CNTs), when used as a filler in two types of polymers, are fully destructed in a pilot-scale combustion unit designed to mimic the combustion under waste incineration. The two polymer nanocomposites studied, polycarbonate (PC) with CNT and high-density polyethylene (HDPE) with CNT, were incinerated at two temperatures where the lower temperature just about fulfilled the European waste incineration directive while the upper was chosen to be on the safe side of fulfilling the directive. Particles in the flue gas were sampled and analysed with online and offline instrumentation along with samples of the bottom ash. CNTs could be identified in the flue gas in all experiments, although present to a greater extent when the CNTs were introduced in PC as compared to in HDPE. In the case of using PC as polymer matrix, CNTs were identified in 3-10% of the analysed SEM images while for HDPE in only ~0.5% of the images. In the case of PC, the presence of CNTs decreased with increasing bed temperature (from 10% to 3% of the images). The CNTs identified were always in bundles, often coated with remnants of the polymer, forming particles of ~1-4 μm in diameter. No CNTs were identified in the bottom ash, likely explained by the difference in time when the bottom ash and fly ash are exposed to high temperatures (~hours compared to seconds) in the pilot facility. The results suggest that the residence time of the fly ash in the combustion zone is not long enough to allow full oxidation of the CNTs. Thus, the current regulation on waste incineration (requiring a residence time of the flue gas >850 °C during at least 2 s) may not be enough to obtain complete destruction of CNTs in polymer composites. Since several types of CNTs are known to be toxic, we stress the need for further investigation of the fate and toxicity of CNTs in waste treatment processes., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.) more...
- Published
- 2021
- Full Text
- View/download PDF
10. Surfactant-Free Stabilization of Aqueous Graphene Dispersions Using Starch as a Dispersing Agent.
- Author
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Zhao W, Sugunan A, Gillgren T, Larsson JA, Zhang ZB, Zhang SL, Nordgren N, Sommertune J, and Ahniyaz A
- Abstract
Attention to graphene dispersions in water with the aid of natural polymers is increasing with improved awareness of sustainability. However, the function of biopolymers that can act as dispersing agents in graphene dispersions is not well understood. In particular, the use of starch to disperse pristine graphene materials deserves further investigation. Here, we report the processing conditions of aqueous graphene dispersions using unmodified starch. We have found that the graphene content of the starch-graphene dispersion is dependent on the starch fraction. The starch-graphene sheets are few-layer graphene with a lateral size of 3.2 μm. Furthermore, topographical images of these starch-graphene sheets confirm the adsorption of starch nanoparticles with a height around 5 nm on the graphene surface. The adsorbed starch nanoparticles are ascribed to extend the storage time of the starch-graphene dispersion up to 1 month compared to spontaneous aggregation in a nonstabilized graphene dispersion without starch. Moreover, the ability to retain water by starch is reduced in the presence of graphene, likely due to environmental changes in the hydroxyl groups responsible for starch-water interactions. These findings demonstrate that starch can disperse graphene with a low oxygen content in water. The aqueous starch-graphene dispersion provides tremendous opportunities for environmental-friendly packaging applications., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.) more...
- Published
- 2021
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11. Functionalized magnetic particles for water treatment.
- Author
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Baresel C, Schaller V, Jonasson C, Johansson C, Bordes R, Chauhan V, Sugunan A, Sommertune J, and Welling S
- Abstract
In this study, we have taken the concept of water treatment by functionalized magnetic particles one step forward by integrating the technology into a complete proof of concept, which included the preparation of surface modified beads, their use as highly selective absorbents for heavy metals ions (Zinc, Nickel), and their performance in terms of magnetic separation. The separation characteristics were studied both through experiments and by simulations. The data gathered from these experimental works enabled the elaboration of various scenarios for Life Cycle Analysis (LCA). The LCA showed that the environmental impact of the system is highly dependent on the recovery rate of the magnetic particles. The absolute impact on climate change varied significantly among the scenarios studied and the recovery rates. The results support the hypothesis that chelation specificity, magnetic separation and bead recovery should be optimized to specific targets and applications. more...
- Published
- 2019
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12. The impact of N,N-dimethyldodecylamine N-oxide (DDAO) concentration on the crystallisation of sodium dodecyl sulfate (SDS) systems and the resulting changes to crystal structure, shape and the kinetics of crystal growth.
- Author
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Summerton E, Hollamby MJ, Zimbitas G, Snow T, Smith AJ, Sommertune J, Bettiol J, Jones C, Britton MM, and Bakalis S
- Abstract
Hypothesis: At low temperatures stability issues arise in commercial detergent products when surfactant crystallisation occurs, a process which is not currently well-understood. An understanding of the phase transition can be obtained using a simple binary SDS (sodium dodecyl sulfate) + DDAO (N,N-dimethyldodecylamine N-oxide) aqueous system. It expected that the crystallisation temperature of an SDS system can be lowered with addition of DDAO, thus providing a route to improve detergent stability., Experiments: Detergent systems are typically comprised of anionic surfactants, non-ionic surfactants and water. This study explores the crystallisation of a three component system consisting of sodium dodecyl sulfate (SDS), N,N-dimethyldodecylamine N-oxide (DDAO), and water using wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC) and confocal Raman microscopy., Findings: The presence of DDAO lowered the crystallisation temperature of a 20 wt% SDS system. For all aqueous mixtures of SDS + DDAO at low temperatures, SDS hydrated crystals, SDS.1/2H
2 O or SDS·H2 O, formed. SDS hydrates comprising of layers of SDS separated by water layers. DDAO tended to reside in the vicinity of these SDS crystals. In the absence of DDAO an additional intermediary hydrate structure, SDS.1/8H2 O, formed whereas for mixed SDS + DDAO systems no such structure was detected during crystallisation., (Copyright © 2018. Published by Elsevier Inc.) more...- Published
- 2018
- Full Text
- View/download PDF
13. Nitric Oxide Dependent Degradation of Polyethylene Glycol-Modified Single-Walled Carbon Nanotubes: Implications for Intra-Articular Delivery.
- Author
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Bhattacharya K, Sacchetti C, Costa PM, Sommertune J, Brandner BD, Magrini A, Rosato N, Bottini N, Bottini M, and Fadeel B
- Subjects
- Animals, Chondrocytes pathology, Female, Injections, Intra-Articular, Knee Joint pathology, Mice, RAW 264.7 Cells, Chondrocytes metabolism, Knee Joint metabolism, Nanotubes, Carbon chemistry, Nitric Oxide metabolism, Polyethylene Glycols chemistry
- Abstract
Polyethylene glycol (PEG)-modified carbon nanotubes have been successfully employed for intra-articular delivery in mice without systemic or local toxicity. However, the fate of the delivery system itself remains to be understood. In this study 2 kDa PEG-modified single-walled carbon nanotubes (PNTs) are synthesized, and trafficking and degradation following intra-articular injection into the knee-joint of healthy mice are studied. Using confocal Raman microspectroscopy, PNTs can be imaged in the knee-joint and are found to either egress from the synovial cavity or undergo biodegradation over a period of 3 weeks. Raman analysis discloses that PNTs are oxidatively degraded mainly in the chondrocyte-rich cartilage and meniscus regions while PNTs can also be detected in the synovial membrane regions, where macrophages can be found. Furthermore, using murine chondrocyte (ATDC-5) and macrophage (RAW264.7) cell lines, biodegradation of PNTs in activated, nitric oxide (NO)-producing chondrocytes, which is blocked upon pharmacological inhibition of inducible nitric oxide synthase (iNOS), can be shown. Biodegradation of PNTs in macrophages is also noted, but after a longer period of incubation. Finally, cell-free degradation of PNTs upon incubation with the peroxynitrite-generating compound, SIN-1 is demonstrated. The present study paves the way for the use of PNTs as delivery systems in the treatment of diseases of the joint., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.) more...
- Published
- 2018
- Full Text
- View/download PDF
14. Polymer/Iron Oxide Nanoparticle Composites--A Straight Forward and Scalable Synthesis Approach.
- Author
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Sommertune J, Sugunan A, Ahniyaz A, Bejhed RS, Sarwe A, Johansson C, Balceris C, Ludwig F, Posth O, and Fornara A
- Subjects
- Magnetic Resonance Imaging methods, Particle Size, Ferric Compounds chemistry, Magnetite Nanoparticles chemistry, Polymers chemistry
- Abstract
Magnetic nanoparticle systems can be divided into single-core nanoparticles (with only one magnetic core per particle) and magnetic multi-core nanoparticles (with several magnetic cores per particle). Here, we report multi-core nanoparticle synthesis based on a controlled precipitation process within a well-defined oil in water emulsion to trap the superparamagnetic iron oxide nanoparticles (SPION) in a range of polymer matrices of choice, such as poly(styrene), poly(lactid acid), poly(methyl methacrylate), and poly(caprolactone). Multi-core particles were obtained within the Z-average size range of 130 to 340 nm. With the aim to combine the fast room temperature magnetic relaxation of small individual cores with high magnetization of the ensemble of SPIONs, we used small (<10 nm) core nanoparticles. The performed synthesis is highly flexible with respect to the choice of polymer and SPION loading and gives rise to multi-core particles with interesting magnetic properties and magnetic resonance imaging (MRI) contrast efficacy. more...
- Published
- 2015
- Full Text
- View/download PDF
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