| 1. |
- Alipour, Nazanin, et al.
(författare)
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Qualitative characterization of nanoclay particle emissions from PP nanocomposites after thermal degradation
- 2015
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Ingår i: 20th International Conference on Composite Materials, ICCM 2015. - : International Committee on Composite Materials.
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Konferensbidrag (refereegranskat)abstract
- The use of nanomaterials in polymeric materials is a rapidly expanding field, and the polymer nanocomposites are being introduced into various markets. But there is still little known about the fate of nanocomposites and nanoparticles during service life and end-of-life of the materials. To avoid possible environmental, health and safety problems, simulating different scenarios for nanoparticles release from the polymer matrix plays a key role in commercialization of these advanced materials. The polymer/nanoclay nanocomposites show superior material properties in comparison with the pure polymers, such as improved mechanical properties, heat resistance, flame retardancy and decreased gas permeability. Polypropylene (PP) nanocomposites have attracted a considerable interest due to the material's low cost, low density and extensive production volumes. In this study, in order to obtain reliable results regarding the release of nanoclays from PP nanocomposites, homogenous composite with predetermined content of nanoclay was produced and characterized to obtain information regarding content, dispersion and size of the nanoclays in the matrix. The PP nanocomposite was degraded under controlled conditions and the surface morphology as well as oxidation of the material was characterized with scanning electron microscopy (SEM) and infrared spectroscopy during degradation. A prototype environmental chamber was designed in order to collect nano-sized particles in a controlled manner and subsequent characterization of the released or formed particles was performed with transmission electron microscopy (TEM) and the exposed nanocomposite was analysed with thermogravimetric analysis (TGA).
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| 2. |
- Alipour, Nazanin, et al.
(författare)
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Release of micro- and nanoparticles from a polypropylene/clay nanocomposite, a methodology for controlled degradation and evaluation
- 2021
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Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 319
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Tidskriftsartikel (refereegranskat)abstract
- A methodology was developed for qualitative assessment and characterisation of particle losses from nanocomposites during service life. The methodology can be generalised to other systems where the material fragments during ageing and can be extended to quantitative analysis. A chamber was constructed for ageing of selected materials, which enabled effective collection and subsequent analysis of released particles. A combination of scanning and transmission electron microscopy and energy dispersive X-ray spectroscopy was found to be suitable for characterising particles in terms of size, shape and content. The methodology was tested on a common nanoclay composite with polypropylene as the matrix. There was no need for physical/mechanical wear to generate particles, slow flow of air and elevated temperature led to cracking and fragmentation of the material, and subsequent release of nanocomposite particles containing embedded or protruding clay. The release of pure clay particles and polypropylene particles was also detected. Using the methodology, it was observed that even in ‘mild’ degradation conditions (pure thermo-oxidation with no wear), fillers and nanocomposite particles can be released to the environment, which is an environmental and health concern. © 2021 The Authors
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| 3. |
- Apel, Christina, et al.
(författare)
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Safe-and-sustainable-by-design: State of the art approaches and lessons learned from value chain perspectives
- 2024
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Ingår i: Current Opinion in Green and Sustainable Chemistry. - Stockholm : IVL Svenska Miljöinstitutet. - 2452-2236. ; 45, s. 100876-100876
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Tidskriftsartikel (refereegranskat)abstract
- Safe-and-sustainable-by-design (SSbD) is central in the European Chemicals Strategy for Sustainability, yet a common understanding of what SSbD is in concept and in practice isstill needed. A comparison of current SSbD descriptions and approaches was made and lessons learned were derived from value chain discussions (packaging, textile, construction,automotive, energy materials, electronics, and fragrances value chains) to help provide input on how to implement SSbD in practice.Five important building blocks were identified:design, data, risk and sustainability governance, competencies, and social and corporate strategic needs. Other lessons learned include the identification of the biggest safety andsustainability challenges in a lifecycle-thinking approach towards the development of purpose-driven innovations, and connecting trans-disciplinary experts to the innovation process, already from the early phases. A clear understanding of what SSbD is and how to implement the SSbD framework is needed with clear procedures and incentives to support the industrial sector, especially SMEs.
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| 4. |
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| 5. |
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| 6. |
- Atari Jabarzadeh, Sevil, et al.
(författare)
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Image Analysis Determination of the Influence of Surface Structure of Silicone Rubbers on Biofouling
- 2015
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Ingår i: International Journal of Polymer Science. - : Hindawi Limited. - 1687-9422 .- 1687-9430.
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on how the texture of the silicone rubber material affects the distribution of microbial growth on the surface of materials used for high voltage insulation. The analysis of surface wetting properties showed that the textured surfaces provide higher receding contact angles and therefore lower contact angle hysteresis. The textured surfaces decrease the risk for dry band formation and thus preserve the electrical properties of the material due to a more homogeneous distribution of water on the surface, which, however, promotes the formation of more extensive biofilms. The samples were inoculated with fungal suspension and incubated in a microenvironment chamber simulating authentic conditions in the field. The extent and distribution of microbial growth on the textured and plane surface samples representing the different parts of the insulator housing that is shank and shed were determined by visual inspection and image analysis methods. The results showed that the microbial growth was evenly distributed on the surface of the textured samples but restricted to limited areas on the plane samples. More intensive microbial growth was determined on the textured samples representing sheds. It would therefore be preferable to use the textured surface silicone rubber for the shank of the insulator.
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| 7. |
- Atari Jabarzadeh, Sevil, et al.
(författare)
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Use of essential oils for the prevention of biofilm formation on silicone rubber high voltage insulators
- 2015
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Ingår i: Polymers from Renewable Resources. - : Rapra Technology Ltd.. - 2041-2479 .- 2045-1377. ; 6:4, s. 119-136
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Tidskriftsartikel (refereegranskat)abstract
- The prevention of biofilm formation on high voltage insulators is important to avoid changes in the surface properties of the material and the subsequent failure of the application. Antimicrobial silicone rubber samples were prepared by the addition of thymol and eugenol to Sylgard 184 to determine the possibility of using natural antimicrobial agents present in essential oils in materials used for high voltage insulators. The antimicrobial effects of thymol and eugenol were studied for different fungal strains and for green algae identified in the biofilms formed on insulators in Tanzania, Sri Lanka and Sweden. It was successfully demonstrated that samples containing high amount of eugenol and different concentrations of thymol could inhibit the fungal growth of strains from Sri Lanka and Tanzania and the growth of green algae. The growth of strains from Sweden was also suppressed. The addition of eugenol to the material resulted in a noncrosslinked system and therefore, the antimicrobial effect of the additive in the material could not be assessed. The addition of thymol did not significantly influence the thermal and mechanical properties of Sylgard184. Although thermal analysis revealed that a large amount of the antimicrobial agent was lost during sample preparation, the materials were effective against microbial growth, even at low thymol concentrations.
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| 8. |
- Atarijabarzadeh, Sevil, et al.
(författare)
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Biofilm formation on silicone materials containing various antimicrobial agents
- 2010
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Konferensbidrag (refereegranskat)abstract
- The colonisation of microorganisms and subsequent biofilm formation on the surface of polymeric high voltage insulators affect the surface properties and can lead to failure of the insulators. In this study, silicone materials were prepared with different antimicrobial agents. The materials were analysed for the changes in the physical, chemical, surface and mechanical properties before and after biological growth test. Microorganisms used for the biological tests were fungi defined in the international standard test ISO 846 for electrical applications (Aspergillus niger van Tieghem, Penicillium funiculosum Thom, Paecilomyces variotii Bainier, Chaetomium globosum Kunze: Fries, Aspergillus terreus Thom, Aureobasidium pullulans (de Bary) Arnaud & Penicillium ochrochloron Biourge) and algae isolated from insulators in Sri Lanka and Tanzania (Chlorella vulgaris var. Autotrophica + various bacterial strains). Fungi growth test was performed by inoculation of the fungi on the surface of the materials and incubation in an oven at 28°C and 98% humidity for a specific period. Algae growth test was performed by inoculation on the material surface and subsequent incubation in room temperature under a constant fluorescent lamps for a specific period. The results indicated that some of the samples could prevent the biofilm formation on the surface of the materials while the microbial growth was unaffected on the pure silicone rubber.
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| 9. |
- Atarijabarzadeh, Sevil, et al.
(författare)
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Biofilm formation on silicone nanocomposites containing different antimicrobial agents
- 2010
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Konferensbidrag (refereegranskat)abstract
- In this study three types of clay/silicon nanocomposites were prepared. Clay was modified with two different antimicrobial agents (p-aminobenzoic acid and partially aminated poly(vinylbenzyl chloride) and used for preparation of the nanocomposites, which aimed to show antimicrobial properties and also easy dispersion of the clay into the polymeric matrix. Reference nanocomposites were made through the modification of the clay with a siloxane surfactant to make an easy dispersion of the clay into the silicone rubber. Nanocomposites were studied for resistancy against biological attack according to the international standard tests. Growth test results indicated that some of the nanocomposites can inhibit biological growth more than pristine nanocomposites. Modified clay was studied with x-ray diffraction technique. Materials were also studied with scanning electron microscopy before and after biological growth to analyse the biofilm formation on the surface.
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| 10. |
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| 11. |
- Atarijabarzadeh, Sevil, et al.
(författare)
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Inhibition of biofilm formation on silicone rubber samples using various antimicrobial agents
- 2011
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier BV. - 0964-8305 .- 1879-0208. ; 65:8, s. 1111-1118
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature-cured silicone rubber samples (silicone rubber (SIR) based on polydimethylsiloxane (PDMS)) and SIR samples containing three different antimicrobial agents, sodium benzoate (NaB), DCOIT (4,5 Dichloro-2-octyl-2H-isothiazolone-one) and p-aminobenzoic acid (PABA) were inoculated with fungal spore suspensions and incubated for 28 days at 29 +/- 1 degrees C and >= 90% humidity, according to the ISO 846:1997(E) protocol. Prior to the biodegradation test, a powder test was conducted to study the efficacy of the chosen antimicrobial compounds and to determine the correct concentration of the compounds for sample preparation. The extent of the microbial growth was studied visually and by Scanning Electron Microscopy (SEM). Changes in surface hydrophobicity and surface chemical composition were studied by contact angle measurements and Fourier Transform Infrared (FTIR) spectroscopy, respectively. Microbial growth and biofilm formation were observed on the surface of reference samples. DCOIT was the most effective antimicrobial agent, as demonstrated by the lack of microbial growth and unaltered surface hydrophobicity. On the surface of samples containing NaB, an initiation of microbial growth and therefore a slight change in surface hydrophobicity was observed. PABA did not inhibit the fungal growth.
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| 12. |
- Badia, J. D., et al.
(författare)
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A statistical design of experiments for optimizing the MALDI-TOF-MS sample preparation of polymers. An application in the assessment of the thermo-mechanical degradation mechanisms of poly (ethylene terephthalate)
- 2011
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 692:1-2, s. 85-95
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Tidskriftsartikel (refereegranskat)abstract
- The sample preparation procedure for MALDI-TOF MS of polymers is addressed in this study by the application of a statistical Design of Experiments (DoE). Industrial poly (ethylene terephthalate) (PET) was chosen as model polymer. Different experimental settings (levels) for matrixes, analyte/matrix proportions and concentrations of cationization agent were considered. The quality parameters used for the analysis were signal-to-noise ratio and resolution. A closer inspection of the statistical results provided the study not only with the best combination of factors for the MALDI sample preparation, but also with a better understanding of the influence of the different factors, individually or in combination, to the signal. The application of DoE for the improvement of the MALDI measure of PET stated that the best combination of factors and levels was the following: matrix (dithranol), proportion analyte/matrix/cationization agent (1/15/1, V/V/V), and concentration of cationization agent (2 g L-1). In a second part, multiple processing by means of successive injection cycles was used to simulate the thermo-mechanical degradation effects on the oligomeric distribution of PET under mechanical recycling. The application of MALDI-TOF-MS showed that thermo-mechanical degradation primarily affected initially predominant cyclic species. Several degradation mechanisms were proposed, remarking intramolecular transesterification and hydrolysis. The ether links of the glycol unit in PET were shown to act as potential reaction sites, driving the main reactions of degradation.
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| 13. |
- Badia, J. D., et al.
(författare)
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Assessing the MALDI-TOF MS sample preparation procedure to analyze the influence of thermo-oxidative ageing and thermo-mechanical degradation on poly (Lactide)
- 2011
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Ingår i: European Polymer Journal. - : Elsevier BV. - 0014-3057 .- 1873-1945. ; 47:7, s. 1416-1428
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Tidskriftsartikel (refereegranskat)abstract
- Multiple processing by means of successive injection cycles was used to simulate the thermo-mechanical degradation effects on the oligomeric distribution of PLA under mechanical recycling. Likewise, an accelerated thermal ageing over PLA glass transition was performed in order to simulate its service life. MALDI-TOF MS was used for the analysis and the sample preparation procedure was assessed by means of a statistical Design of Experiments (DoE). The quality effects in use for the analysis were signal-to-noise ratio and Resolution. Different matrixes, analyte/matrix proportions and the use of NaTFA as cationization agent were considered. A deep inspection of the statistical results provided a better understanding of the influence of the different factors, individually or in combination, to the signal. The application of DoE for the improvement of the MALDI measurement of PLA stated that the best combination of factors (levels) was the following: matrix (s-DHB), proportion analyte/matrix (1/5 V/V), and no use of cationization agent. Degradation primarily affected the initially predominant cyclic [LA(C)](n) and linear H-[LA(L)](n)-OH species, where LA stands for a PLA repeating unit. Intramolecular and intermolecular transesterifications as well as hydrolytic and homolytic reactions took place during the formation and disappearance of oligomeric species. In both degradation mechanisms induced by thermal ageing and thermo-mechanical degradation, the formation of H-[LA(L)](n)-O-CH(3) by intermolecular transesterifications was highlighted.
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| 14. |
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| 15. |
- Badia, J. D., et al.
(författare)
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Effect of sisal and hydrothermal ageing on the dielectric behaviour of polylactide/sisal biocomposites
- 2017
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Ingår i: Composites Science And Technology. - : Elsevier. - 0266-3538 .- 1879-1050. ; 149, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- The dielectric properties of virgin polylactide (PLA) and its reinforced composites with different weight amounts of sisal fibres were assessed at broad temperature (from −130 °C to 130 °C) and frequency ranges (from 10−2–107 Hz), before and after being subjected to accelerated hydrothermal ageing. The synergetic effects of both the loading of sisal and hydrothermal ageing were analysed by means of dielectric relaxation spectra. The relaxation time functions were evaluated by the Havriliak-Negami model, substracting the ohmic contribution of conductivity. The intramolecular and intermolecular relaxations were respectively analysed by means of Arrhenius and Vogel-Fulcher-Tammann-Hesse thermal activation models. The addition of fibre increased the number of hydrogen bonds, which incremented the dielectric permittivity and mainly hindered the non-cooperative relaxations of the biocomposites by increasing the activation energy. Hydrothermal ageing enhanced the formation of the crystalline phase at the so-called transcrystalline region along sisal. This fact hindered the movement of the amorphous PLA fraction, and consequently decreased the dielectric permittivity and increased the dynamic fragility.
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| 16. |
- Badia, J.D., et al.
(författare)
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Material valorisation of amorphous polylactide. Influence of thermo-mechanical degradation on the morphology, segmental dynamics, thermal and mechanical performance
- 2012
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Ingår i: Polymer degradation and stability. - : Elsevier BV. - 0141-3910 .- 1873-2321. ; 97:4, s. 670-678
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the effects of multiple mechanical recycling on the structure and properties of amorphous polylactide (PIA). The influence of the thermo-mechanical degradation induced by means of five successive injection cycles was initially addressed in terms of macroscopic mechanical properties and surface modification. A deeper inspection on the structure and morphology of PLA was associated to the thermal properties and viscoelastic behaviour. Although FT-IR analysis did not show significant changes in functional groups, a remarkable reduction in molar mass was found by viscometry. PIA remained amorphous throughout the reprocessing cycles, but the occurrence of a cold-crystallization during DSC and DMTA measurements, which enthalpy increased with each reprocessing step, suggested chain scission due to thermo-mechanical degradation. The effect of chain shortening on the glass-rubber relaxation studied by DMTA showed an increase in free volume affecting the segmental dynamics of PLA, particularly after the application of the second reprocessing step, in connection to the overall loss of performance showed by the remaining properties.
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| 17. |
- Badia, J. D., et al.
(författare)
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Relevant factors for the eco-design of polylactide/sisal biocomposites to control biodegradation in soil in an end-of-life scenario
- 2017
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Ingår i: Polymer degradation and stability. - : Elsevier. - 0141-3910 .- 1873-2321. ; 143, s. 9-19
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Tidskriftsartikel (refereegranskat)abstract
- The eco-design considers the factors to prepare biocomposites under an end-of-life scenario. PLA/sisal biocomposites were obtained from amorphous polylactide and sisal loadings of 10, 20 and 30 wt% with and without coupling agent, and subjected to biodegradation in soil according to standard ISO846. Mass-loss, differential scanning calorimetry and size-exclusion chromatography were used for monitoring biodegradation. A statistical factorial analysis based on the molar mass Mn and crystallinity degree XC pointed out the relevance and interaction of amount of fibre and use of coupling agent with the time of burial in soil. During the preparation of biocomposites, chain scission provoked a similar reduction of Mn for coupled and non-coupled biocomposites. The amount of fibre was relevant for the increase of XC due to the increase of nucleation sites. The coupling agent accelerated the evolution of both factors: reduction of Mn and the consequent increase of XC, mainly during biodegradation in soil. Both factors should be balanced to facilitate microbial assimilation of polymer segments, since bacterial digestion is enhanced by chain scission but blocked by the promotion of crystalline fractions.
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| 18. |
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| 19. |
- Badia, J.D., et al.
(författare)
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The role of crystalline, mobile amorphous and rigid amorphous fractions on the performance of recycled poly (ethylene terephthalate) (PET)
- 2012
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Ingår i: Polymer degradation and stability. - : Elsevier BV. - 0141-3910 .- 1873-2321. ; 97:1, s. 98-107
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Tidskriftsartikel (refereegranskat)abstract
- The action of thermo-mechanical degradation induced by mechanical recycling of poly(ethylene terephthalate) was simulated by successive injection moulding cycles. Degradation reactions provoked chain scissions and a reduction in molar mass mainly driven by the reduction of diethyleneglycol to ethylene glycol units in the flexible domain of the PET backbone, and the formation ofeOH terminated species with shorter chain length. The consequent microstructural changes were quantified taking into account a three-fraction model involving crystalline, mobile amorphous (MAF) and rigid amorphous fractions (RAF). A remarkable increase of RAF, to a detriment of MAF was observed, while the percentage of crystalline fraction remained nearly constant. A deeper analysis of the melting behaviour, the segmental dynamics around the glass-rubber relaxation, and the macroscopic mechanical performance, showed the role of each fraction leading to a loss of thermal, viscoelastic and mechanical features, particularly remarkable after the first processing cycle.
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| 20. |
- Badia, J. D., et al.
(författare)
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Water absorption and hydrothermal performance of PHBV/sisal biocomposites
- 2014
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Ingår i: Polymer degradation and stability. - : Elsevier BV. - 0141-3910 .- 1873-2321. ; 108, s. 166-174
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Tidskriftsartikel (refereegranskat)abstract
- The performance of biocomposites of poly(hydroxybutyrate-co-valerate) (PHBV) and sisal fibre subjected to hydrothermal tests at different temperatures above the glass transition of PHBV (T-H = 26, 36 and 46 degrees C) was evaluated in this study. The influences of both the fibre content and presence of coupling agent were focused. The water absorption capability and water diffusion rate were considered for a statistical factorial analysis. Afterwards, the physico-chemical properties of water-saturated biocomposites were assessed by Fourier-Transform Infrared Analysis, Size Exclusion Chromatography, Differential Scanning Calorimetry and Scanning Electron Microscopy. It was found that the water diffusion rate increased with both temperature and percentage of fibre, whereas the amount of absorbed water was only influenced by fibre content. The use of coupling agent was only relevant at the initial stages of the hydrothermal test, giving an increase in the diffusion rate. Although the chemical structure and thermal properties of water-saturated biocomposites remained practically intact, the physical performance was considerably affected, due to the swelling of fibres, which internally blew-up the PHBV matrix, provoking cracks and fibre detachment.
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| 21. |
- Beheshti, Reza, 1981-
(författare)
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Sustainable Aluminum and Iron Production
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aluminium recycling requires 95% less energy than primary production with no loss of quality. The Black Dross (BD) produced during secondary aluminium production contains high amounts of water-soluble compounds, therefore it is considered as a toxic waste. In the present work, salt removal from BD by thermal treatment has been investigated in laboratory scale. The optimum conditions for treatment were established, i.e., temperature, gas flow rate, holding time, rotation rate, and sample size. The overall degree of chloride removal was established to increase as a function of time and temperature. Even Pretreated Black Dross (PBD) was evaluated as a possible raw material for the production of a calcium aluminate-based ladle-fluxing agent to be used in the steel industry. The effects of different process parameters on the properties of the produced flux were experimentally investigated, i.e. CaO/Al2O3 ratio, temperature, holding time, and cooling media. The utilization of PBD as the alumina source during the production of a calcium aluminate fluxing agent shows promising results. The iron/steel industry is responsible for 9% of anthropogenic energy and process CO2 emissions. It is believed that the only way to a long-term reduction of the CO2 emissions from the iron/steel industry is commercialization of alternative processes such as Direct Reduction (DR) of iron oxide. Detailed knowledge of the kinetics of the reduction reactions is, however, a prerequisite for the design and optimization of the DR process. To obtain a better understanding of the reduction kinetics, a model was developed step-by-step, from a single pellet to a fixed bed with many pellets. The equations were solved using the commercial software COMSOL Multiphysics®. The final model considers the reaction rate and mass transfer inside the pellet, as well as the mass transfers and heat transfer in the fixed bed. All the models were verified against experimental results, and where found to describe the results in a satisfying way.
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| 22. |
- Brännström, Sara, et al.
(författare)
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Bioråvara till plast : nuläge och trender
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I denna rapport presenteras möjliga bioråvaror som kan användas för att producera biobaserad plast och potentiella plastalternativ som är under utveckling eller redan finns tillgängliga på marknaden. Kartläggningen har utgjorts av litteraturgranskning samt intervjuer med olika aktörer inom området.Kartläggningen av bioråvarupotentialen hade fokus på råvara från skog, jordbruk, hav samt från biologiskt avfall. Generellt framgår att potentialen är störst för skogsbaserad råvara, följt av jordbruksbaserad råvara och biologiskt avfall, medan potentialen för havsbaserad råvara är minst. Projektet har kartlagt vilken produktionskapacitet som finns tillgänglig för biobaserad plast, främst avseende drop-in-plaster, som är direkt utbytbara med etablerade plaster, men även ersättningsplaster. Globalt är idag endast cirka en procent av plastproduktionen biobaserad. En övervägande del av dagens petrokemibaserade plaster produceras helt eller delvis via krackning av nafta och av det följer att om man kan konvertera biomassa in i det flödet får man in biobaserad råvara i alla dessa plaster, således för polyeten (PE), liksom för polypropen (PP) och polyetentereftalat (PET), som är de tre mängdmässigt största plastsorterna. Biobaserade plaster med annan molekylstruktur än dagens högvolymplaster, här kallat ersättningsplaster, är ännu ganska sparsamt förekommande på marknaden. Det är främst polymjölksyra (PLA) som används, och produktionskapaciteten ökar globalt. En slutsats som dras i studien är att det pågår lovande utveckling och en långsam men stadig ökning av biobaserad plast, men att det är först runt 2030, och därefter, som bioråvara till plast, och plast från bioråvara, kommer att vara tillgänglig i större mängder.
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| 23. |
- Christiansson, Lisa, et al.
(författare)
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Increased Level of Myeloid-Derived Suppressor Cells, Programmed Death Receptor Ligand 1/Programmed Death Receptor 1, and Soluble CD25 in Sokal High Risk Chronic Myeloid Leukemia
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:1, s. e55818-
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Tidskriftsartikel (refereegranskat)abstract
- Immunotherapy (eg interferon α) in combination with tyrosine kinase inhibitors is currently in clinical trials for treatment of chronic myeloid leukemia (CML). Cancer patients commonly have problems with so called immune escape mechanisms that may hamper immunotherapy. Hence, to study the function of the immune system in CML is of interest. In the present paper we have identified immune escape mechanisms in CML with focus on those that directly hamper T cells since these cells are important to control tumor progression. CML patient samples were investigated for the presence of myeloid-derived suppressor cells (MDSCs), expression of programmed death receptor ligand 1/programmed death receptor 1 (PD-L1/PD-1), arginase 1 and soluble CD25. MDSC levels were increased in samples from Sokal high risk patients (p<0,05) and the cells were present on both CD34 negative and CD34 positive cell populations. Furthermore, expression of the MDSC-associated molecule arginase 1, known to inhibit T cells, was increased in the patients (p = 0,0079). Myeloid cells upregulated PD-L1 (p<0,05) and the receptor PD-1 was present on T cells. However, PD-L1 blockade did not increase T cell proliferation but upregulated IL-2 secretion. Finally, soluble CD25 was increased in high risk patients (p<0,0001). In conclusion T cells in CML patients may be under the control of different immune escape mechanisms that could hamper the use of immunotherapy in these patients. These escape mechanisms should be monitored in trials to understand their importance and how to overcome the immune suppression.
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| 24. |
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| 25. |
- Edvardsson Björnberg, Karin, et al.
(författare)
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Integrating social sustainability in engineering education at the KTH Royal Institute of Technology
- 2015
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Ingår i: International Journal of Sustainability in Higher Education. - 1467-6370 .- 1758-6739. ; 16:5, s. 639-649
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - The purpose of this paper is to investigate what are perceived to be the main challenges associated with the integration of social sustainability into engineering education at the KTH Royal Institute of Technology, Stockholm. Design/methodology/approach - Semi-structured interviews were conducted with programme leaders and teachers from four engineering programmes. The paper focuses on how the concept of social sustainability is defined and operationalised in the selected engineering programmes, how social sustainability is integrated and taught, and what resources are required to support teachers and programme leaders as social sustainability educators. Findings - The findings show that programme leaders and teachers at KTH struggle to understand the concept of social sustainability. The vague and value-laden nature of the concept is considered a challenge when operationalising educational policy goals on social sustainability into effective learning outcomes and activities. A consequence is that the responsibility for lesson content ultimately falls on the individual teacher. Study visits and role-play are seen as the most effective tools when integrating social sustainability into the engineering curriculum. Allocation of specific resources including supplementary sustainability training for teachers and economic incentives are considered crucial to successful integration of social sustainability. The findings indicate that social sustainability education needs to be built on a theoretical foundation. It is therefore suggested that a literature canon be established that clarifies the contours of social sustainability. Practical implications - The findings of the paper can be used as a basis for discussion regarding measures for improving social sustainability training in engineering education, a subject which has attracted relatively little attention, to date. Originality/value - There is a noticeable lack of empirical research on how technical universities integrate social sustainability into engineering education. The paper provides an account of how actors directly involved in this work - programme leaders and teachers - define and operationalise the social dimension of sustainable development in their engineering curricula, the pedagogical tools they consider effective when teaching social sustainability issues to engineering students, and the resources they believe are needed to strengthen those efforts.
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| 26. |
- Edvardsson Björnberg, Karin, et al.
(författare)
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Integrating social sustainability into the engineering curriculum at the Royal Institute of Technology (KTH) : A pilot study
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, significant efforts have been made at the Royal Institute of Technology (KTH) in Stockholm to integrate sustainable development in the university’s Bachelor and Master education. However, a self-evaluation study carried out in 2012 showed that many programme coordinators and teachers at KTH still struggle with how to integrate social sustainability in their programmes. Based on interviews with programme coordinators at four engineering programmes at KTH we analyse what are perceived to be the main challenges associated with integration of social sustainability in the university’s engineering education. The paper reports on data acquired through the interviews, focusing on three questions: (1) How is the concept of social sustainability defined and operationalized in the selected engineering programmes? (2) How is social sustainability taught in the selected engineering programmes (learning objectives, teaching methods, pedagogical strategies/tools)? (3) What resources (training efforts, material/tools, etc.) are (according to the informants) required in order to support teachers and programming coordinators in their professional roles as (social) sustainability educators?
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| 27. |
- Engdahl, Johan, 1968, et al.
(författare)
-
Geographic and socio-demographic differences in uptake of population-based screening for atrial fibrillation: The STROKESTOP I study
- 2016
-
Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 222, s. 430-435
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The rationale behind screening for atrial fibrillation (AF) is to prevent ischemic stroke. Socio-demographic differences are expected to affect screening uptake. Geographic differences may provide further insights leading to targeted interventions for improved uptake. The objective of this study was to evaluate geographic and socio-demographic differences in uptake of AF screening in the population-based study STROKESTOP I. METHODS: STROKESTOP was carried out in two Swedish counties with a total population of 2.3 million inhabitants. Half of the residents aged 75-76years were randomized to the screening arm: invitation to clinical examination followed by ambulant ECG recording. Information on each invited person's residential parish (n=157) was used. On parish-level, aggregated data for the participants and non-participants, respectively, were obtained with respect to socioeconomic variables: educational level, disposable income, immigrant and marital status. Geo-maps displaying participation ratios were estimated by hierarchical Bayes methods. RESULTS: The overall participation rate was similar in men and women but lower in Stockholm, 47.6% (5665/11,903) than in Halland, 61.2% (1495/2443). Participation was clearly associated with the socioeconomic variables. Participation not taking into account socioeconomy varied more markedly across the parishes in the Stockholm county (range: 0.65-1.26) than in the Halland county (0.94-1.27). After adjustment for socioeconomic variables, a geographic variation remained in Stockholm, but not in Halland. CONCLUSION: Participation in AF screening varied according to socioeconomic conditions. Geographic variation in participation was marked in the Stockholm county, with only one screening clinic. Geo-mapping of participation yielded useful information needed to intervene for improved screening uptake.
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| 28. |
- Finnveden, Göran, 1961-, et al.
(författare)
-
A Holistic Approach for Integration of Sustainable Development in Education, Research, Collaboration and Operations
- 2017
-
Ingår i: Handbook of Theory and Practice of Sustainable Development in Higher Education. - Cham : Springer. - 9783319478883 ; , s. 287-303
-
Bokkapitel (refereegranskat)abstract
- In 2011 KTH Royal Institute of Technology started several new sustainable development initiatives. This paper will report on the journey. An Environmental Management System for the entire university has been established and KTH became ISO 14001 certified during 2015. The system includes operations but also education, research and collaboration. In this way we ensure that sustainability goals are integrated in the management system and that improvements are required continuously. For education an aim is that all educational programs should be able to report how they have integrated sustainability. The activities are focused on two complementary approaches: evaluation of the program’s work and providing tools and support for teaching staff and program directors. Preliminary results from the on-going evaluation indicate that progress has been made in several programs, but there is still room for improvements. For research, several bibliometric and external funding indicators show progress. During the winter of 2015 an evaluation was conducted and based on this it was decided that the activities should continue. A new policy for sustainable development as well as new sustainable development goals were decided during 2015.
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| 29. |
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| 30. |
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| 31. |
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| 32. |
- Frostell, Claes, et al.
(författare)
-
Tracheal implants revisited
- 2017
-
Ingår i: The Lancet. - : ELSEVIER SCIENCE INC. - 0140-6736 .- 1474-547X. ; 389:10075, s. 1191-1191
-
Tidskriftsartikel (refereegranskat)
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| 33. |
- Fråne, Anna, et al.
(författare)
-
Potential för ökad återanvändning och materialåtervinning för transportförpackningar i plast från verksamheter
- 2022
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Transportförpackningar av plast används inom ett flertal branscher i samhället där de tillför en nödvändig lösning för skydd och effektivare transport av varor och komponenter. Det finns dock utmaningar med den stora mängden plast som används idag. Den största volymen framställs från fossila råvaror som till stor del hamnar i förbränningsprocesser, vilket resulterar i fossila växthusgasutsläpp. Plastflöden behöver i större utsträckning ingå i cirkulära system, där insamling, materialåtervinning och återanvändning av plastprodukter måste öka. Förpackningar är den största produktgruppen för plastanvändning och är därmed en viktig grupp för ökad återanvändning och materialåtervinning. Denna rapport fokuserar på möjligheter för ökad cirkuläritet för transportförpackningar av plast. Syftet har varit att samla in information från olika branscher för ökad kunskap om plastflöden inom transportförpackningar och undersöka potentialen för ökad återanvändning och materialåtervinning av dessa.Undersökningen genomfördes genom en omfattande litteraturstudie och dialog med olika aktörer inom sju branscher via individuella intervjuer, referensgruppmöten och en workshop. De identifierade utmaningarna och den potential för ökad återanvändning och materialåtervinning som kom fram under intervjuerna och vid workshopen analyserades för respektive bransch med hjälp av kvalitativ bedömning och olika hinder (generella och branschspecifika) identifierades. Därefter togs ett antal åtgärdsförslag och fyra målbilder fram för att nå målet med ökad återanvändning och materialåtervinning av transportförpackningar av plast. Målbilderna innehåller både styrmedelsförslag och systemlösningar samt kategoriserades utefter (i) hinder som adresseras, (ii) incitament och (iii) vision för år 2025.Det är svårt att få en uppfattning om plastflödena eftersom det inte finns statistik över hur stora mängder transportförpackningar av plast som tillverkas eller används i Sverige varje år. Producenter är skyldiga att rapportera hur stor mängd plastförpackningar de totalt sätter på marknaden varav hur stor mängd som utgörs av konsumentförpackningar. Av den officiella förpackningsstatistiken går det därför att särskilja konsumentförpackningar från den totala mängden, men hur stor mängd som utgörs av just transportförpackningar av plast finns det ingen statistik över. Bland aktörerna själva saknas också kunskap om hur mycket plast som de använt sig av, materialval, hur leverantörer kan påverkas och vilka lösningar som andra använder sig av. För att åtgärda detta är det viktigt med informationshöjande insatser. En arbetsgrupp inom den nationella plastsamordningen kan samla aktörer längs med transportförpackningars värdekedja för att öka förståelsen över branscher och därmed öka materialåtervinningen och återanvändningen.Efter användningen kan transportförpackningarna sorteras ut till materialåtervinning (egen fraktion eller tillsammans med annat plastavfall), hamna i avfallsfraktioner som går till energiutvinning eller återanvändas inom cirkulära system. Genom intervjuer har det framkommit att det förekommer brister i hur transportförpackningar av plast eftersorteras, där det inom vissa branscher går till den brännbara fraktionen mer ofta på grund av platsbrist eller att det inte anses lönsamt. Kostnaderna för insamling och behandling av förpackningsavfall täcks i regel av förpackningsavgifter som ingår i priset av en förpackad vara och förpackningsavgifternas storlek skiljer sig. Systemet för verksamhetsförpackningar är inte lika utvecklat som för konsumentförpackningar och det finns idag ingen differentiering av avgifter för verksamhetsförpackningar.Utökade krav på insamling, eftersortering, och återanvändbarhet för att därmed kunna nå ökad materialåtervinningsgrad ökar incitamenten för att lösa exempelvis platsbristen. Kraven kan dessutom innebära att kunskapsgraden och statistiken förbättras eftersom aktörerna blir mer medvetna om transportförpackningars hantering samtidigt som ökade plastflöden kan säkerställa ökad kvalitet på återvunnen råvara och att transportförpackningarna designas för att kunna återanvändas. Vad undersökningen slutligen landar i är det faktum att transportförpackningar av plast behöver utbyggd infrastruktur, med teknik för plaståtervinning och gemensamma branschöverskridande system för återanvändning, för att kunna säkerställa cirkuläritet och därmed nå målen om ökad materialåtervinning och ökad återanvändning.
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| 34. |
- García-García, Daniel, et al.
(författare)
-
Reinforcing capability of cellulose nanocrystals obtained from pine cones in a biodegradable poly(3-hydroxybutyrate)/poly(ε-caprolactone) (PHB/PCL) thermoplastic blend
- 2018
-
Ingår i: European Polymer Journal. - : Elsevier. - 0014-3057 .- 1873-1945. ; 104, s. 10-18
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, different loads (3, 5 and 7 wt%) of pine cone cellulose nanocrystals (CNCs) were added to films ofpoly(3-hydroxybutyrate)/poly(ε-caprolactone) (PHB/PCL) blends with a composition of 75 wt% PHB and 25 wt% PCL (PHB75/PCL25). The films were obtained after solvent casting followed by melt compounding in anextruder and finally subjected to a thermocompression process. The influence of different CNCs loadings on themechanical, thermal, optical, wettability and disintegration in controlled compost properties of the PHB75/PCL25blend was discussed. Field emission scanning electron microscopy (FESEM) revealed the best dispersion of CNCson the polymeric matrix was at a load of 3 wt%. Over this loading, CNCs aggregates were formed enhancing thefilms fragilization due to stress concentration phenomena. However, the addition of CNCs improved the opticalproperties of the PHB75/PCL25films by increasing their transparency and accelerated the film disintegration incontrolled soil conditions. In general, the blend with 3 wt% CNCs offers the best balanced properties in terms ofmechanical, thermal, optical and wettability
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| 35. |
- Gil-Castell, O., et al.
(författare)
-
Effect of the dissolution time into an acid hydrolytic solvent to taylor electrospun nanofibrous polycaprolactone scaffolds
- 2017
-
Ingår i: European Polymer Journal. - : Elsevier. - 0014-3057 .- 1873-1945. ; 87, s. 174-187
-
Tidskriftsartikel (refereegranskat)abstract
- The hydrolysis of the polycaprolactone (PCL) as a function of the dissolution time in a formic/acetic acid mixture was considered as a method for tailoring the morphology of nanofibrous PCL scaffolds. Hence, the aim of this research was to establish a correlation between the dissolution time of the polymer in the acid solvent with the physico-chemical properties of the electrospun nanofibrous scaffolds and their further service life behaviour. The physico-chemical properties of the scaffolds were assessed in terms of fibre morphology, molar mass and thermal behaviour. A reduction of the molar mass and the lamellar thickness as well as an increase of the crystallinity degree were observed as a function of dissolution time. Bead-free fibres were found after 24 and 48 h of dissolution time, with similar diameter distributions. The decrease of the fibre diameter distributions along with the apparition of beads was especially significant for scaffolds prepared after 72 h and 120 h of dissolution time in the acid mixture. The service life of the obtained devices was evaluated by means of in vitro validation under abiotic physiological conditions. All the scaffolds maintained the nanofibrous structure after 100 days of immersion in water and PBS. The molar mass was barely affected and the crystallinity degree and the lamellar thickness increased along immersion, preventing scaffolds from degradation. Scaffolds prepared after 24 h and 48 h kept their fibre diameters, whereas those prepared after 72 h and 120 h showed a significant reduction. This PCL tailoring procedure to obtain scaffolds that maintain the nanoscaled structure after such long in vitro evaluation will bring new opportunities in the design of long-term biomedical patches.
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| 36. |
- Gil-Castell, O., et al.
(författare)
-
Hydrothermal ageing of polylactide/sisal biocomposites. Studies of water absorption behaviour and Physico-Chemical performance
- 2014
-
Ingår i: Polymer degradation and stability. - : Elsevier BV. - 0141-3910 .- 1873-2321. ; 108, s. 212-222
-
Tidskriftsartikel (refereegranskat)abstract
- An accelerated hydrothermal degrading test was designed in order to analyse the synergic effect of water and temperature on PLA/sisal biocomposites with and without coupling agent. As well, the physicochemical properties of biocomposites were monitored along the hydrothermal test by means of Scanning Electron Microscopy, Size Exclusion Chromatography and Differential Scanning Calorimetry. The addition of fibre induced higher water absorption capability and promoted physical degradation, as observed in the surface topography. During the processing of biocomposites and throughout the hydrothermal ageing, a reduction of molecular weight due to chain scission was found. As a consequence, a faster formation of crystalline domains in the PIA matrix occurred the higher the amount of fibre was, which acted as a nucleating agent. Higher crystallinity was considered as a barrier against the advance of penetrant and a reduction in the diffusion coefficient was shown. The addition of coupling agent presented a different influence depending on the composition, showing an inflection point around 20% of sisal fibre.
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| 37. |
- Gil-Castell, O., et al.
(författare)
-
Impact of hydrothermal ageing on the thermal stability, morphology and viscoelastic performance of PLA/sisal biocomposites
- 2016
-
Ingår i: Polymer degradation and stability. - : Elsevier. - 0141-3910 .- 1873-2321.
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of the combined exposure to water and temperature on the behaviour of polylactide/sisal biocomposites coupled with maleic acid anhydride was assessed through accelerated hydrothermal ageing. The biocomposites were immersed in water at temperatures from 65 to 85 °C, between the glass transition and cold crystallisation of the PLA matrix. The results showed that the most influent factor for water absorption was the percentage of fibres, followed by the presence of coupling agent, whereas the effect of the temperature was not significant. Deep assessment was devoted to biocomposites subjected to hydrothermal ageing at 85 °C, since it represents the extreme degrading condition. The morphology and crystallinity of the biocomposites were evaluated by means of X-Ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The viscoelastic and thermal performance were assessed by means of dynamic mechanic thermal analysis (DMTA) and thermogravimetry (TGA). The presence of sisal generally diminished the thermal stability of the biocomposites, which was mitigated by the addition of the coupling agent. After composite preparation, the effectiveness of the sisal fibre was improved by the crystallisation of PLA around sisal, which increased the storage modulus and reduced the dampening factor. The presence of the coupling agent strengthened this effect. After hydrothermal ageing, crystallisation was promoted in all biocomposites therefore showing more fragile behaviour evidencing pores and cracks. However, the addition of coupling agent in the formulation of biocomposites contributed in all cases to minimise the effects of hydrothermal ageing.
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| 38. |
- Hallberg, Elisabet, et al.
(författare)
-
Miljöbedömning av matavfallsemballage - Livscykelanalys av olika påsalternativ
- 2018
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Matavfall används ofta i Sverige för att producera biogödsel och biogas. Olika typer av matavfallsemballage (matavfallspåsar) kan användas för insamling av matavfall, t ex: plastpåsar av polyeten (fossil- eller bio-baserade), påsar från material baserade på majs- eller potatisstärkelse, papperspåsar. Alternativen har olika egenskaper och olika fördelar och nackdelar. Många kommuner i Sverige ställer krav på en specifik typ av emballage som ska användas. Idag finns det inga speciella krav för matavfallsemballage för insamling av matavfall i Uppsala kommun och hushållen väljer själva vilken typ av påse som används. Uppsala Vatten vill undersöka om det ur hållbarhetssynpunkt finns skäl att göra förändringar av dagens insamlingssystem. I den här studien gjordes en miljöutvärdering av olika typer av matavfallsemballage för insamling från hushåll. Projektets syfte var att adressera frågeställningen hur matavfallsemballage av olika material påverkar klimatprestandan för insamling och rötning av matavfall. Studien har, genom livscykelanalys (LCA), utforskat, utvärderat och dokumenterat klimatpåverkan från olika matavfallsemballage längs hela värdekedjan. Olika fördelar och nackdelar av materialval samt distribution av matavfallspåsar har också identifierats med hjälp av intervjuer med olika kommuner och företag i Sverige. De olika typerna av påsar för matavfallsemballage som har analyserats i den här studien är: fossil polyeten (PE), (bärkasse och avfallspåse på rulle); återvunnen PE (bärkasse och avfallspåse på rulle), bio-baserad PE (bärkasse och avfallspåse på rulle) samt kompostpåse (papper). En viktig del av en LCA-beräkning är att sätta systemgränser för vilka delar av livscykeln som beräkningen ska täcka in. Detta beror i sin tur på hur produkten används. I denna studie har t. ex. inte tillverkningen av råvara och påse tagits med i beräkningen för plastbärkassar p.g.a. att de främst är tillverkade för att användas till ett annat ändamål. För avfallspåse på rulle och kompostpåse av papper inkluderas däremot denna tillverkning eftersom dessa påsar enbart är avsedda att användas som matavfallsemballage. Resultaten visar att bärkassen av bio-baserad PE faller bäst ut ur klimatsynpunkt eftersom utsläppet av koldioxid (CO2) vid förbränning av bio-baserad PE är biogent och därmed enligt praxis inte räknas som ett bidrag till antropogen klimatpåverkan och dessutom exkluderas tillverkningen av råvara och påse. Det bör dock påpekas att valet av en bio-baserad PE bärkasse sällan är ett val man som konsument själv kan styra över eftersom tillgången regleras av butikernas val av material i påsar. Om man enbart jämför påsar som produceras för ändamålet att samla in matavfall (där ”uppströms produktion” inkluderas) är papperspåse (kompostpåse) bästa alternativet, och avfallspåse på rulle av fossil PE faller ut sämst ur klimatsynpunkt. Att kompostpåse av papper är det mest gynnsamma alternativet, beror främst på att utsläppet av koldioxid (CO2) vid förbränning av papper är biogent (analogt med fallet för bio-baserad PE). Påverkan från tillverkningen av råvaran (papper) samt påstillverkningen är också lägre för papperspåsen. Under studien observerades dock att resultaten är mycket känsliga för vissa osäkra parametrar, t ex: antagande om volym av matavfall per påse, mängder av producerad biogödsel och biogas samt biogödselkvalitet. Känslighetsanalyser visade att dessa parametrar kan påverka jämförelsen mellan påsarna och behöver därmed studeras mer för att säkerställa pålitliga resultat.
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| 39. |
- Högfeldt, Anna-Karin, et al.
(författare)
-
Leading the teacher team - balancing between formal and informal power in program leadership
- 2018
-
Ingår i: Tertiary Education and Management. - : Springer Nature. - 1358-3883 .- 1573-1936. ; 24:1, s. 49-65
-
Tidskriftsartikel (refereegranskat)abstract
- This continuous research within Nordic engineering institutions targets the contexts and possibilities for leadership among engineering education program directors. The IFP-model, developed based on analysis of interviews with program leaders in these institutions, visualizes the program director's informal and formal power. The model is presented as a tool for starting a shared discussion on the complexities of the leadership of engineering program development. The authors liken program development to hunting in teams. Each individual expert in the program is needed, and all experts will need to work and collaborate for the same target. This calls for strategic and long-term thinking of engineering education development. Institutions should support the development of both formal structures as well as informal leadership skills among their program directors, but never fall for the temptation to see the program director as the only actor on the stage.
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| 40. |
- Högfeldt, Anna-Karin, et al.
(författare)
-
Program leadership from a nordic perspective : Program leaders' power to influence their program
- 2013
-
Ingår i: Proceedings of the 9th International CDIO Conference.
-
Konferensbidrag (refereegranskat)abstract
- In this paper a continuation research at five technical universities in Nordic countries (N5T network) in 2012 is presented, wheretheaim was to find out how the program leadersconceived their function, role and mandate, and the work situations between the universitieswere compared. The previous research demonstrated that programleadershave quite different positions, strategies and methods when it comes to monitoring and developing their programs.In this paper, a deeper investigationis carried out ofthe (im-) possibilitiesto make realinfluence on the study courses that constitutesthe respective Engineering study programs. Eightprogram leaders from thefiveN5Tuniversities have been interviewed, and theanalysis of these studies, has culminatedina model for the analysis of program leadership for Engineering educationdevelopment.
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| 41. |
- Högfeldt, Anna-Karin, et al.
(författare)
-
Program leadership from a Nordic perspective - Program leaders' power to influence their program
- 2013
-
Ingår i: Proceedings of the 9th International CDIO Conference, Cambridge, USA.
-
Konferensbidrag (refereegranskat)abstract
- In this paper a continuation research at five technical universities in Nordic countries (N5T network) in 2012 is presented, where the aim was to find out how the program leaders conceived their function, role and mandate, and the work situations between the universities were compared. The previous research demonstrated that program leaders have quite different positions, strategies and methods when it comes to monitoring and developing their programs. In this paper, a deeper investigation is carried out of the (im-) possibilities to make real influence on the study courses that constitutes the respective Engineering study programs. Eight program leaders from the five N5T universities have been interviewed, and the analysis of these studies, has culminated in a model for the analysis of program leadership for Engineering education development.
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| 42. |
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| 43. |
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| 44. |
- Kaali, Peter, et al.
(författare)
-
Antimicrobial properties of Ag+ loaded zeolite polyester polyurethane and silicone rubber and long-term properties after exposure to in-vitro ageing
- 2010
-
Ingår i: Polymer degradation and stability. - : Elsevier BV. - 0141-3910 .- 1873-2321. ; 95:9, s. 1456-1465
-
Tidskriftsartikel (refereegranskat)abstract
- In biomedical applications, tubes (e.g. catheters etc.) are commonly produced from polyurethane (PU) and silicone rubber which are known to be biocompatible materials. Several studies have shown that tubes, which are connected to the body (invasive) (especially urinary, tracheotomy and central venous catheters) are associated with infections. The present study reports the development of a new method aiming at obtaining antibacterial properties for PU and silicone rubber by mixing respective material with a natural antibacterial agent (Ag+ loaded zeolite) in different weight fractions. The influence of the zeolite content on the antimicrobial properties were analysed by exposure to bacteria (ISO 22196) and mixtures of fungi (ISO 846). The materials were also subject to artificial body fluids (Artificial Lysosomal Fluid (ALF) and Gamble's solution) for periods up to three months and the subsequent changes in the chemical properties after in-vitro exposure were determined by Matrix Assisted Laser Deposition/Ionization Time Of Flight Mass Spectrometry (MALDI-TOF MS) and Attenuated Total Reflection Fourier Transform Infra Red spectroscopy (ATR-FTIR). It was established that the antimicrobial effect of the materials increased with the increase of the zeolite content. The wettability of the materials was found to decrease significantly during the in-vitro exposure, but this could not be correlated to the zeolite content. In the PU samples, the formation of free carbonyl and -OH groups was observed, which corresponds to oxidative degradation. In case of the silicone rubber the ratio of cyclic PDMS to linear PDMS (H, CH3 and dimethyl terminated) decreased, which indicates a change in the concentration of the compounds. The formation and increase of the O-H bond during the exposure was also confirmed by the infrared spectra of the material which corresponds to hydrolysis of the silicone rubber.
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| 45. |
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| 46. |
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| 47. |
- Kaali, Peter, et al.
(författare)
-
The influence of Ag(+), Zn(2+) and Cu(2+) exchanged zeolite on antimicrobial and long term in vitro stability of medical grade polyether polyurethane
- 2011
-
Ingår i: Express Polymer Letters. - : Department of Polymer Engineering, Scientific Society of Mechanical Engineering. - 1788-618X. ; 5:12, s. 1028-1040
-
Tidskriftsartikel (refereegranskat)abstract
- This study aims to investigate the limitations and applicability of different ion exchanged zeolites as antimicrobial additive in thermoplastic polyether type polyurethanes. These composites were designed to improve the health quality of hospitalized patients by expressing both biocompatibility and relevant antimicrobial activity. The zeolites were exchanged with silver, copper and zinc ions and single, binary and ternary ion-exchanged zeolite-polyurethane composites were prepared. The antimicrobial activity and the resistance of the composites against the human environment play vital role in the applicability of the materials as a medical device therefore these properties were investigated. The antimicrobial test were performed on Methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Candida tropicalis. The tests showed that the efficiency of the silver ions is superior to the other single ionic systems. Besides, the binary and ternary ion-exchanged samples had similar antimicrobial efficiency regardless the type of the ions in the zeolite. The biocompatibility tests were carried out in-vitro in artificial body fluids for a period of 12 weeks. As a result of the in-vitro test, degradation of the composites were observed and the structural changes of the materials were detected and described by Scanning Electron Microscopy, Contact Angle measurements and Attenuated Total Reflection Fourier Transform Infrared Spectroscopy.
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| 48. |
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| 49. |
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| 50. |
- Karlsson, Hannah, et al.
(författare)
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Evaluation of Intracellular Signaling Downstream Chimeric Antigen Receptors
- 2015
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:12
-
Tidskriftsartikel (refereegranskat)abstract
- CD19-targeting CAR T cells have shown potency in clinical trials targeting B cell leukemia. Although mainly second generation (2G) CARs carrying CD28 or 4-1BB have been investigated in patients, preclinical studies suggest that third generation (3G) CARs with both CD28 and 4-1BB have enhanced capacity. However, little is known about the intracellular signaling pathways downstream of CARs. In the present work, we have analyzed the signaling capacity post antigen stimulation in both 2G and 3G CARs. 3G CAR T cells expanded better than 2G CAR T cells upon repeated stimulation with IL-2 and autologous B cells. An antigen-driven accumulation of CAR+ cells was evident post antigen stimulation. The cytotoxicity of both 2G and 3G CAR T cells was maintained by repeated stimulation. The phosphorylation status of intracellular signaling proteins post antigen stimulation showed that 3G CAR T cells had a higher activation status than 2G. Several proteins involved in signaling downstream the TCR were activated, as were proteins involved in the cell cycle, cell adhesion and exocytosis. In conclusion, 3G CAR T cells had a higher degree of intracellular signaling activity than 2G CARs which may explain the increased proliferative capacity seen in 3G CAR T cells. The study also indicates that there may be other signaling pathways to consider when designing or evaluating new generations of CARs.
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