| 1. |
- Gårdebjer, Sofie, 1985, et al.
(författare)
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The impact of interfaces in laminated packaging on transport of carboxylic acids
- 2016
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 0376-7388 .- 1873-3123. ; 518, s. 305-312
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Tidskriftsartikel (refereegranskat)abstract
- The permeability of oleic and acetic acid through low density polyethylene (LDPE) and ethylene acrylic acid (EAA) have been measured using diffusion cells. In addition, the permeability through combinations of LDPE and EAA in the form of laminates with different numbers of layers has been determined. Oleic acid shows an almost 30 times higher permeability compared to acetic acid, which was partly explained by the adsorption of oleic acid to the film surface during the permeability experiment. In addition, the permeability is lower for both oleic and acetic acid in the laminates compared to the pure films. The decreased permeability can be explained by the presence of crystalline domains close to the interface. This is supported by SAXS data which suggests an ordering of polymer chains in the EAA film close to the interface. In summary, the results show that it is possible to create barrier materials with decreased permeability, which is interesting for example in the packaging industry.
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| 2. |
- Andersson, Peter, 1981-, et al.
(författare)
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Coincidence spectroscopy for increased sensitivity in radionuclide monitoring
- 2022
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The majority of the energy in a nuclear explosion is released in the immediate blast and the initial radiation accounts. The remaining fraction is released through radioactive decay of the explosion's fission products and neutron activation products over a longer time span. This allows for the detection of a nuclear explosion by detecting the presence of residual decay. Radionuclide monitoring stations for detection of radioactive emissions to the atmosphere is thereby an important tool in the verification of compliance with nuclear disarmament treaties. In particular, the globally spanning radionuclide station network of the International Monitoring System (IMS) has been implemented for verification of the Comprehensive Nuclear-Test-Ban Treaty.High Purity Germanium (HPGe) detectors are workhorses in radionuclide monitoring. The detection of characteristic gamma rays can be used to disclose the presence of signature nuclides produced innuclear weapon tests. A particular development that has potential to improve the sensitivity of radionuclide monitoring is the coincidence technique where decaying nuclides that emit several coincident gamma rays can be detected at much smaller activity concentrations than with conventional gamma spectroscopy.In this project, dedicated gamma-gamma coincidence detectors are being developed, utilizing electronically segmented HPGe detectors. These detectors are expected to be highly sensitive to low-activity samples of nuclides that present coincident emissions of gamma rays. In this paper we present the concept, define performance parameters, and explore the performance of such detectors to a subset of radionuclides of particular CTBT relevance. In addition, we discuss the path forward in developing a next generation gamma-gamma coincidence spectroscopy system of segmented HPGe.
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| 3. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
-
Charged microcapsules for controlled release of hydrophobic actives. Part III: The effect of polyelectrolyte brush- and multilayers on sustained release
- 2013
-
Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 15:17, s. 6153-6165
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Tidskriftsartikel (refereegranskat)abstract
- Poly(methyl methacrylate) microspheres have been prepared by the internal phase separation method using either of the three conventional dispersants poly(vinyl alcohol) (PVA), poly(methacrylic acid) (PMAA), or the amphiphilic block copolymer poly(methyl methacrylate)-block-poly(sodium methacrylate). The block copolymer based microsphere, which has a polyelectrolyte brush on the surface, was surface modified with up to two poly(diallyldimethylammonium chloride)-poly(sodium methacrylate) bilayers. The microspheres were loaded with the hydrophobic dye 2-(4-(2-chloro-4-nitrophenylazo)-N-ethylphenylamino)ethanol (Disperse Red 13) and its release from aqueous dispersions of microspheres with the different surface compositions was measured by spectrophotometry. The burst fraction, burst rate and the diffusion constant were determined from a model combining burst and diffusive release. Out of the three dispersants, the block copolymer gave the slowest release of the dye, with respect to both burst release and diffusive release. A very pronounced further reduction of the diffusion constant was obtained by applying polyelectrolyte multilayers on top of the microspheres. However, the diffusion constant was very weakly dependent on further polyelectrolyte adsorption and one polyelectrolyte bilayer appeared to suffice.
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| 4. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
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Directed self-assembly of silica nanoparticles in ionic liquid-spun cellulose fibers
- 2019
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 553, s. 167-176
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Tidskriftsartikel (refereegranskat)abstract
- The application range of man-made cellulosic fibers is limited by the absence of cost- and manufacturing-efficient strategies for anisotropic hierarchical functionalization. Overcoming these bottlenecks is therefore pivotal in the pursuit of a future bio-based economy. Here, we demonstrate that colloidal silica nanoparticles (NPs), which are cheap, biocompatible and easy to chemically modify, enable the control of the cross-sectional morphology and surface topography of ionic liquid-spun cellulose fibers. These properties are tailored by the silica NPs’ surface chemistry and their entry point during the wet-spinning process (dope solution DSiO2 or coagulation bath CSiO2). For CSiO2-modified fibers, the coagulation mitigator dimethylsulphoxide allows for controlling the surface topography and the amalgamation of the silica NPs into the fiber matrix. For dope-modified fibers, we hypothesize that cellulose chains act as seeds for directed silica NP self-assembly. This results for DSiO2 in discrete micron-sized rods, homogeneously distributed throughout the fiber and for glycidoxy-surface modified DSiO2@GLYEO in nano-sized surface aggregates and a cross-sectional core-shell fiber morphology. Furthermore, the dope-modified fibers display outstanding strength and toughness, which are both characteristic features of biological biocomposites.
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| 5. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
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Encapsulation of actives for sustained release
- 2013
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 15:41, s. 17727-17741
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Forskningsöversikt (refereegranskat)abstract
- Encapsulation of actives in miniature reservoirs, called microcapsules, is used for protection and in particular controlled release of the active. Regarding controlled release applications, the most common function of the microcapsule is to sustain or extend the release of the active. A number of encapsulation methodologies are available including; internal phase separation, interfacial polymerization, formation of multiple emulsions, Layer-by-Layer adsorption of polyelectrolytes and soft templating techniques, all of which are reviewed in this Perspective. The choice of method depends on the nature of the active (hydrophilic/hydrophobic, size, physical state) and on the intended release rate and release profile. Ways to manipulate the release of the active by tailoring the physicochemical properties of the microcapsule are reviewed. Moreover, appropriate diffusion models are introduced to describe the release profile from a variety of microcapsule morphologies, including Fickian diffusion models and Brownian motion, and the meaning and the misuse of the term ``zero-order release'' are briefly discussed.
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| 6. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
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Quantitative Grafting for Structure-Function Establishment: Thermoresponsive Poly(alkylene oxide) Graft Copolymers Based on Hyaluronic Acid and Carboxymethylcellulose
- 2019
-
Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 20:3, s. 1271-1280
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 American Chemical Society. A series of thermoresponsive graft copolymers, gelling at physiological conditions in aqueous solution and cell growth media, have been synthesized using quantitative coupling between a small set of amino-functionalized poly(alkylene oxide) copolymers (PAO) and the carboxylate of the biologically important polysaccharides (PSa) carboxymethylcellulose and the less reactive hyaluronate. Quantitative grafting enables the establishment of structure-function relationship which is imperative for controlling the properties of in situ gelling hydrogels. The EDC/NHS-mediated reaction was monitored using SEC-MALLS, which revealed that all PAOs were grafted onto the PSa backbone. Aqueous solutions of the graft copolymers were Newtonian fluids at room temperatures and formed reversible physical gels at elevated temperatures which were noncytotoxic toward chondrocytes. The established structure-function relationship was most clearly demonstrated by inspecting the thermogelling strength and the onset of thermogelling in a phase diagram. The onset of the thermogelling function could be controlled by the global PAO concentration, independent of graft ratio.
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| 7. |
- Al-Dury, S., et al.
(författare)
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Catch-up antibody responses and hybrid immunity in mRNA vaccinated patients at risk of severe COVID-19
- 2023
-
Ingår i: Infectious Diseases. - 2374-4235. ; 55:10, s. 744-750
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundThe immunogenicity of repeated vaccination and hybrid immunity in vulnerable patients remains unclear.MethodsWe studied the impact of iterative Covid-19 mRNA vaccination and hybrid immunity on antibody levels in immunosuppressed subjects. Patients with liver cirrhosis (n = 38), survivors of allogeneic haematopoietic stem cell transplantation (allo-HSCT) (n = 36) and patients with autoimmune liver disease (n = 14) along with healthy controls (n = 20) were monitored for SARS-CoV-2-S1 IgG after their 1st-3rd vaccine doses, 31 of whom became infected with the Omicron variant after the 2nd dose. Ten uninfected allo-HSCT recipients received an additional 4th vaccine dose.ResultsUnexpectedly, immunosuppressed patients achieved antibody levels in parity with controls after the 3rd vaccine dose. In all study cohorts, hybrid immunity (effect of vaccination and natural infection) resulted in approximately 10-fold higher antibody levels than vaccine-induced immunity alone.ConclusionsThree doses of the Covid-19 mRNA vaccine entailed high antibody concentrations even in immunocompromised individuals, and hybrid-immunity resulted further augmented levels than vaccination alone.
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| 8. |
- Andersson, Markus, 1981, et al.
(författare)
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Coordination of Imidazoles by Cu(II) and Zn(II) as Studied by NMR Relaxometry, EPR, far-FTIR Vibrational Spectroscopy and Ab Initio Calculations: Effect of Methyl Substitution
- 2010
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 114:50, s. 13146-13153
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Tidskriftsartikel (refereegranskat)abstract
- Synthetic imidazole ligands are typically substituted at the N-1 ((1)-Im) position while natural imidazole ligands are substituted at the C-4 ((4)-Im) position. To outline the difference in coordination properties, the methyl-substituted imidazoles Me(4)-Im and Me(1)-Im were complexed with CuCl2 and ZnCl2 and investigated by NMR relaxometry, electron paramagnetic resonance, far-Fourier transform IR vibrational spectroscopy, and ab initio calculations. Me(4)-Im, Me(1)-Im, and Im in excess form the usual tetragonal D-4h [CuL4X2] complexes with CuCl2 whereas the methylated imidazoles form pseudotetrahedral C-2v, complexes instead of the usual octahedral O-h [ZnIm(6)](2+) complex. All imidazoles display a high degree of covalence in the M-L sigma- and pi-bonds and the pi-interaction strength affects the relative energies of complexation. Opportunities to tailor complexes by the chemical properties of the substituents are envisaged due to the role of the inductive and hyperconjugative effects, rather than position.
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| 9. |
- Andersson, Markus, 1981
(författare)
-
Imidazole containing polymers complexed with Cu2+ and Zn2
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An enormous problem for the shipping industry is fouling of marine organisms such as algae andbarnacles on the boat hull. The negative consequences for the society are both economical as well asenvironmental. To prevent fouling in general, biocides are typically incorporated directly into the paint.Premature leakage of the biocides is a drawback which reduces the lifetime of the coating and pollutes thesurrounding ecosystems.Microencapsulation is an efficient way of encapsulating active substances for controlling the release andthereby prolonging the antifouling properties of the coating. The rate of release into the marineenvironment is partly governed by the degree of swelling of the shell of the microcapsule. The swelling ofthe microcapsule shell, and hence the release of biocide, may be modified by utilizing imidazolecoordination chemistry towards metal ions in the shell material.The aim of this thesis has been to characterize such coordinating polymer complexes and evaluate theirmaterial properties, solubility characteristics and coordination chemistry as well as synthesising newmaterials. Furthermore it is of interest to outline the coordination properties of imidazole as a function ofsubstitution position since synthetic and natural imidazole ligands in polymers are typically substituted atposition 1 or 4.The coordinating polymer material was studied using DSC, mid-FTIR and far-FTIR vibrationalspectroscopy as well as simple ocular investigation. The coordination chemistry of the coordinatingpolymer material and related coordination compounds were evaluated by far-FTIR and EPR.The reaction between the polymer and the metal ions Cu2+ and Zn2+ cross-links the system and increasesthe glass transition temperature, Tg. Furthermore, the strong coordinate bond between imidazole and themetal ions in the cross-links renders the complex insoluble in conventional solvents, and only stronglycoordinating solvents are able to solubilise the complex. The geometry of the Cu2+ complexes is squareplanar with up to four imidazole ligands and the physical properties of corresponding the Zn2+ complexesindicate a higher coordination number. The metal ions are exclusively coordinated by the imidazole ligandin the polymer. Concerning the effect of ring substitution on the coordination chemistry of imidazole, theresults indicate that the inductive effect of the group attached has a much larger effect than the position ofthe group.ivDue to the significant strength of the coordinate bond, coordination of imidazole by Cu2+ or Zn2+ is anefficient way of almost irreversibly incorporating salts into a hydrophobic polymer material. Polymerscoordinated by metal ions provide the resulting coordinating polymer complex with new materialproperties. The specific aim of this doctoral project is to use these polymer materials to modify the shellof the microcapsule in order to control the rate of release. Due the strongly hygroscopic nature of salts,the tendency for the shell material to swell by water should be significantly enhanced. The contact with seawater will accordingly act as a trigger for release.
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| 10. |
- Andersson, Markus, 1981, et al.
(författare)
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Vinylimidazole copolymers: coordination chemistry, solubility, and cross-linking as function of Cu2+ and Zn2+ complexation
- 2011
-
Ingår i: Colloid and Polymer Science. - : Springer Science and Business Media LLC. - 0303-402X .- 1435-1536. ; 289:12, s. 1361-1372
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Tidskriftsartikel (refereegranskat)abstract
- P(1-VIm-co-MMA) copolymers with 4 or 44 wt.% 1-VIm (abbreviated PVM-4 and PVM-44) where polymerized from 1-VIm (1-vinylimidazole) and methylmethacrylate with azobisisobutyronitrile as initiator and reacted with either Cu(2+) or Zn(2+). The resulting coordinated polymer complexes were studied using ICP-AES, CP/MAS (13)C NMR, conductivity measurements, vibrational spectroscopy (mid-FTIR and far-FTIR), DSC, and EPR. It was established by ICP-AES, CP/MAS (13)C NMR, conductivity, mid-FTIR and EPR measurements that the transition metal ions in the complexes were exclusively coordinated by the imidazole ligand. The coordination geometry is square planar with regard to Cu(II) complexes. The strong interaction between the polymeric imidazole ligand and the transition metal ion cross-links the system, resulting in augmentation of T (g) (the glass transition temperature), especially for copolymers with high relative amount of 1-VIm. The effect of changing metal ion is more complicated and depends on both the strength of the coordinate interaction as well as the coordination number. The solubility of the coordinate polymer complex in conventional solvents is low due to the coordinate cross-links. However, the coordinate polymer complexes are soluble in strongly coordinating solvents such as acetonitrile and dimethylsulfoxide.
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| 11. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
-
A highly hydrophobic anionic surfactant at oil-water, water-polymer and oil-polymer interfaces: Implications for spreading coefficients, polymer interactions and microencapsulation via internal phase separation
- 2013
-
Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects. - : Elsevier BV. - 1873-4359 .- 0927-7757. ; 436, s. 1048-1059
-
Tidskriftsartikel (refereegranskat)abstract
- Multicore-shell particles consisting of a poly(methyl methacrylate) shell and multiple dodecane cores have been prepared via the internal phase separation method using the oil-soluble anionic surfactant sodium 1,5-dioxo-1,5-bis(3,5,5-trimethylhexylocy)-3-((3,5,5 trimethylhexyloxy)carbonyl)pentane-2-sulfonate (TC4) and the water-soluble polycation poly(diallyldimethylammonium chloride) (PDADMAC) in combination as a dispersant pair. The multicore-shell particles have been investigated using SEM, light microscopy and microelectrophoresis. The detailed influence of TC4 on the oil-water, water-polymer and oil-polymer interfaces and its interaction with PDADMAC have been investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D) and different optical tensiometry methods. TC4 stabilizes in particular the polymer-water interface in the presence of PDADMAC instead of the oil-water interface in contrast to water-soluble surfactants. In addition, the oil-polymer interface is stabilized by TC4 which prevents coalescence of the oil droplets and leads to multicore-shell morphology rather than single core-shell.
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| 12. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
-
Charged microcapsules for controlled release of hydrophobic actives. Part 1: encapsulation methodology and interfacial properties
- 2013
-
Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 9:5, s. 1468-1477
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Tidskriftsartikel (refereegranskat)abstract
- Highly charged microcapsules have been prepared using the internal phase separation technique. The charges are introduced by using ionic dispersants, which have been characterized with respect to surface activity with a quartz crystal microbalance with dissipation monitoring and with optical tensiometry. The long-term stability of the microcapsule suspension without excess dispersant, as well as the stability at high ionic strength, have been investigated. Three types of ionic dispersants have been evaluated: a weak polyacid (poly(methacrylic acid)), a small set of ionic amphiphilic block copolymers of poly(methyl methacrylate)-block-poly(sodium (meth) acrylate) type and an oil-soluble anionic surfactant, sodium 1,5-dioxo-1,5-bis(3,5,5-trimethylhexyloxy)-3-((3,5,5-trimethylhexyloxy)carbonyl)pentane-2-sulfonate, in combination with a water-soluble polycation, poly(diallyldimethylammonium chloride). The block copolymer based microcapsule suspension is characterized by a long-term stability, even at high ionic strength, provided by electrostatic and steric stabilization. The weak polyacid based microcapsule suspension is stable for a few weeks, after which aggregation starts due to desorption of the dispersant. The surfactant-polycation based microcapsules appear to have a multicore morphology in contrast to the weak polyacid or block copolymer based microcapsules, which are core-shell particles.
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| 13. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
-
Charged microcapsules for controlled release of hydrophobic actives Part II: Surface modification by LbL adsorption and lipid bilayer formation on properly anchored dispersant layers
- 2013
-
Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 409, s. 8-17
-
Tidskriftsartikel (refereegranskat)abstract
- Charge microcapsules with a dodecane core and a poly(methyl methacrylate) (PMMA) shell have been prepared via the internal phase separation method using ionic dispersants. The microcapsules have subsequently been surface modified with polyelectrolyte multilayers and lipid bilayers. Two types of ionic dispersant systems have been investigated: a small set of ionic amphiphilic block copolymers of poly(methyl methacrylate)-block-poly(sodium (meth)acrylate) type and an oil-soluble anionic surfactant, sodium 1,5-dioxo-1,5-bis(3,5,5-trimethylhexyloxy)-3((3,5,5trimethylhexyloxy)car bonyl)pentane-2-sulfonate, in combination with a water-soluble polycation, poly(diallyldimethylammonium chloride). The Layer-by-Layer adsorption of the polyelectrolyte pair poly(diallydimethylammonium chloride) (350,000 g/mol) and poly(sodium methacrylate) (15,000 g/mol) was successfully made on both microcapsule systems with the formation of very thin multilayers as indicated with quartz crystal microbalance with dissipation monitoring (QCM-D) measurements on model surfaces. Formation of a lipid bilayer on the surface of the microcapsules from liposomes with a charge opposite that of the capsule surface was also proven to be successful as indicated by the C-potential of the microcapsules, the characteristic frequency shift as measured with QCM-D and fluorescence recovery after photobleaching (FRAP) on model systems. However, the proper anchorage of the dispersants in the underlying PMMA surface was key for the successful surface modification.
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| 14. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
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Imidazole and Triazole Coordination Chemistry for Antifouling Coatings
- 2013
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Ingår i: Journal of Chemistry. - : Hindawi Limited. - 2090-9063 .- 2090-9071. ; 2013
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Tidskriftsartikel (refereegranskat)abstract
- Fouling of marine organisms on the hulls of ships is a severe problem for the shipping industry. Many antifouling agents are based on five-membered nitrogen heterocyclic compounds, in particular imidazoles and triazoles. Moreover, imidazole and triazoles are strong ligands for Cu2+ and Cu+, which are both potent antifouling agents. In this review, we summarize a decade of work within our groups concerning imidazole and triazole coordination chemistry for antifouling applications with a particular focus on the very potent antifouling agent medetomidine. The entry starts by providing a detailed theoretical description of the azole-metal coordination chemistry. Some attention will be given to ways to functionalize polymers with azole ligands. Then, the effect of metal coordination in azole-containing polymers with respect to material properties will be discussed. Our work concerning the controlled release of antifouling agents, in particular medetomidine, using azole coordination chemistry will be reviewed. Finally, an outlook will be given describing the potential for tailoring the azole ligand chemistry in polymers with respect to Cu2+ adsorption and Cu2+ Cu+ reduction for antifouling coatings without added biocides.
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| 15. |
- Andersson Trojer, Markus, 1981
(författare)
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Modification of microcapsules for controlled release
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fouling of marine organisms such as algae and barnacles on the boat hull is an enormous problem for the shipping industry. The negative consequences for the society are both economical and environmental. To prevent fouling in general, biocides are typically incorporated directly into the paint. Premature leakage of the biocides is a drawback which reduces the lifetime of the coating and pollutes the surrounding ecosystems. Microencapsulation is an efficient way of encapsulating active substances for controlling the release and thereby prolonging the antifouling properties of the coating. The microcapsules used in this work consist of an oil core and a hydrophobic polymer shell. The rate of release into the marine environment may be further tailored by modifying the microcapsules. Triggered release is achieved by rendering the microcapsule shell water sensitive. This may be accomplished by incorporating salt into the shell using imidazole coordination chemistry. On the other hand, extended release is achieved by improving the barrier properties of the microcapsule. This may be realized by providing the microcapsule with an additional shell, such as a highly charged polyelectrolyte multilayer or a lipid bilayer. The objective of this thesis is subsequently twofold: 1) To synthesize and characterize imidazole containing shell materials with a view to obtain triggered release. 2) To surface modify microcapsules with polyelectrolyte multilayers and lipid bilayers toward extended release.Imidazole containing polymers were synthesized using vinyl and maleimide radical polymerization, as well as grafting techniques comprising maleimide bond formation and epoxide ring opening. The imidazole-containing polymeric materials, with and without the salts CuCl2 or ZnCl2, were characterized using differential scanning calorimetry, electron paramagnetic resonance (EPR) and vibrational spectroscopy. The coordination chemistry of the imidazole-metal ion complex was investigated using vibrational spectroscopy, EPR and ab initio calculations.The imidazole coordination to the transition metal ions Cu2+ and Zn2+ in polymeric materials generates cross-links. The interaction between the imidazole moiety and the transition metal ions is very strong and specific. As a consequence, the coordinating polymer is rendered insoluble in conventional solvents, excluding only strongly coordinating solvents.The specificity and strength of the imidazole-transition metal ion interaction may be used for a variety of applications. However, with respect to the microencapsulation route used in this project, the limited solubility of the coordinating polymer material is unfortunate. The use of strongly coordinating solvents during the microencapsulation results in aggregation and phase separation instead of microcapsule formation.Routes for synthesising highly charged microcapsules for further surface modification were investigated using three types of ionic dispersants; a weak polyacid, a small set of amphiphilic block copolymers and a hydrophobic anionic surfactant in combination with a polycation. The charged microcapsules were subsequently modified with polyelectrolyte multilayers using the Layer-by-Layer technique and with lipid bilayers using lipid vesicle spreading. The microcapsules and model systems thereof were characterized mainly using micro-electrophoresis, light microscopy, optical tensiometry and quartz crystal microbalance with dissipation (QCM-D). The release behaviour in aqueous suspension of a hydrophobic model compound was investigated using UV-Vis spectroscopy.The use of the ionic dispersants facilitated the formation of highly charged microcapsules and the subsequent polyelectrolyte multilayer assembly and lipid bilayer formation were also successful. In particular, the block copolymer based microcapsules displayed excellent properties with respect to high and stable surface charge, as well as long term colloidal stability through electrostatic and steric stabilization. The release of the hydrophobic model compound was considerably reduced after modification with polyelectrolyte multilayers. In addition, the type of dispersant had a significant impact on the release. The block copolymer based microcapsules with a higher charge density had a much lower release compared to the weak polyelectrolyte based microcapsules.The polyelectrolyte multilayer is an efficient barrier against hydrophobic molecules and the low permeability is clearly a result of the high charge density. As of yet, the effect of the lipid bilayers on the release has not been investigated but has a large potential since the permeability may be altered by the lipid composition. A microcapsule consisting of an oil core, a hydrophobic polymer shell, a polyelectrolyte multilayer and a lipid bilayer is a complex release system with large degrees of freedom for tailoring the release behaviour.
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| 16. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
-
Polymer Core-Polymer Shell Particle Formation Enabled by Ultralow Interfacial Tension Via Internal Phase Separation: Morphology Prediction Using the Van Oss Formalism
- 2018
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Ingår i: Colloid and Interface Science Communications. - : Elsevier BV. - 2215-0382. ; 25, s. 36-40
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Tidskriftsartikel (refereegranskat)abstract
- The internal phase separation technique is a versatile method for liquid core-polymer shell formation, yet limited to very hydrophobic core materials and actives. The use of polymeric cores instead circumvents this restriction due to the absent mixing entropy for binary polymer mixtures which allows the polymeric core (and the active) to approach the polarity of the shell. Polystyrene core-shell and janus particles were formulated using polymethylmethacrylate, poly(lactic acid), poly(lactic acid-co-glycolic acid), poly(epsilon-caprolactone) or cellulose triacetate as shell-forming polymers. The morphology and the partitioning was experimentally determined by selectively staining the core and the shell with beta-carotene and methylene blue respectively. In addition, the van Oss formalism was introduced to theoretically predict the thermodynamic equilibrium morphology. As elucidated using the theoretical predictions as well as experimental optical tensiometry, it was found that the driving force for core-shell morphology is, in contrast to liquid core-polymer shell particles, a low core-shell interfacial tension.
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| 17. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
-
Replacement of H-bonded bridged water by transition metal ions in poly(1-vinylimidazole-co-methylmethacrylate) copolymers: A vibrational spectroscopy study using mid-FTIR, far-FTIR and ab initio calculations
- 2012
-
Ingår i: Vibrational Spectroscopy. - : Elsevier BV. - 0924-2031. ; 61, s. 38-42
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Tidskriftsartikel (refereegranskat)abstract
- A detailed structural analysis of the vibrational spectra of hydrophobic PVM (poly(1-vinylimidazole-co-methylmethacrylate)) copolymers PVM-4 (4 wt% 1-VIm) and PVM-44 (44 wt% 1-VIm) is provided with respect to bridging water and subsequent replacement by bridging transition metal ions. PVM-44 (44 wt% 1-VIm) with a high fraction of 1-VIm forms water bridges as evident by the water bending vibration, which is shifted up to 1665 cm(-1). This band vanishes as transition metal ions are introduced and a new band at 952 cm(-1) appears which is ascribed as a delta(ring) band involving the entire [M(Im)(n)](2+) unit. This fact is affirmed using ab initio calculations. The transition metal ions coordinate exclusively the imidazole groups. Although the imidazole associated water is replaced by transition metal ions, the amount of sorbed water for the very hydrophobic PVM-4 is increased as indicated by the nu(OH) region.
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| 18. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
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Self-assembly of lipid domains in the extracellular leaflet of the plasma membrane and models thereof
- 2016
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Ingår i: Current Opinion in Colloid and Interface Science. - : Elsevier BV. - 1359-0294 .- 1879-0399. ; 22, s. 65-72
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Forskningsöversikt (refereegranskat)abstract
- Lipid domain formation and phase coexistence in biological membranes is a subject which has received considerable attention during the last two decades, especially the topic concerning so-called lipid rafts, a theory which has become as popular to confirm as to disproof. Regardless of the existence or precise composition and function of the classical rafts, the occurrence of lateral lipid segregation in biological membranes is indisputable. This review starts by focusing on state of the art findings concerning lipid domains and lateral heterogeneity in a biological context. Then, the physicochemical properties of lipid mixtures, phase properties and domain dynamics are considered. Canonical lipid models of the exofacial leaflet of the plasma membrane are treated in detail and the proper choices of model lipids are discussed. A special attention is given to polar lateral interactions (including carbohydrate-carbohydrate head group interactions), whose importance for spatial segregation and crystallization is commencing to be appreciated by the scientific community.
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| 19. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
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Synthesis and polymerisation of maleolyl-L-histidine monomers and addition of histidine to an ethylene-alt-maleic co-polymer
- 2012
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Ingår i: Journal of Polymer Research. - : Springer Science and Business Media LLC. - 1572-8935 .- 1022-9760. ; 19:2, s. 9821-9829
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Tidskriftsartikel (refereegranskat)abstract
- This work has investigated two routes of synthesising polymers containing L-histidine using maleimide chemistry; grafting of histidine onto an ethylene-alt-maleic anhydride copolymer and AIBN (azobisisobutyronitrile) initiated radical polymerisation of the monomer maleoyl-L-histidine. The grafting technique and monomer synthesis are utilising the maleimide formation between the primary amine of histidine and maleic anhydride. The reactions are conveniently carried out in one step with good yields. The copolymers containing L-histidine were prepared by reacting L-histidine or L-histidine methyl ester with poly(ethylene-alt maleic anhydride) in DMSO at 50 °C for 8–16 h with 80% yields independent of the degree of substitution. The monomer maleoyl-L-histidine was synthesised by reacting histidine and maleic anhydride in acetic acid and the monomer was subsequently polymerised by AIBN radical initiation in DMSO at 80 °C for 48 h to yield poly(N-histidyl maleimide). The resulting polymer had a different optical rotation ([α]D20 = −11) than the monomer ([α]D20 = +25), which is ascribed to the threo-diisotactic and/or threo-disyndiotactic stereoregularity of the polymer.
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| 20. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
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The effect of pH on charge, swelling and desorption of the dispersant poly(methacrylic acid) from poly(methyl methacrylate) microcapsules
- 2012
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 375:1, s. 213-215
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Tidskriftsartikel (refereegranskat)abstract
- Poly(methyl methacrylate) microcapsules have been prepared using the solvent evaporation technique with poly(methacrylic acid) (PMAA) as dispersant. The charge, swelling and desorption of PMAA from the microcapsules after treating the suspension with base have been followed using microelectrophoresis, X-ray photoelectron spectroscopy and quartz crystal microbalance with dissipation monitoring on model PMMA surfaces. Basic treatment of the microcapsule suspension leads to temporary colloidal stability through the introduction of charges on the PMAA chain. However, the increase in charge causes a continuous desorption of PMAA from the microcapsule surface, eventually leading to aggregation. If instead poly(diallyldimethylammonium chloride) is added to the base treated microcapsule suspension, good colloidal stability is obtained.
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| 21. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
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The Importance of Proper Anchoring of an Amphiphilic Dispersant for Colloidal Stability
- 2012
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 28:19, s. 4047-4050
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Tidskriftsartikel (refereegranskat)abstract
- Highly stable poly(methyl methacrylate) (PMMA) based microcapsule suspensions without excess dispersant are obtained via the solvent evaporation route using poly(methyl methacrylate)-block-poly(sodium methacrylate) or poly(methyl methacrylate)-block-poly(sodium acrylate) diblock copolymers as dispersant. The stable suspension is characterized by a high ζ-potential that does not change with time or after washing steps. It is indirectly proven on model PMMA surfaces using quartz crystal microbalance with dissipation monitoring that the PMMA block of the copolymer is embedded in the underlying PMMA microcapsule. Such anchoring of the dispersant is key for the good colloidal stability.
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| 22. |
- Andersson Trojer, Markus, 1981, et al.
(författare)
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Use of microcapsules as controlled release devices for coatings
- 2015
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Ingår i: Advances in Colloid and Interface Science. - : Elsevier BV. - 0001-8686. ; 222, s. 18-43
-
Tidskriftsartikel (refereegranskat)abstract
- Biofouling of surfaces is a considerable problem in many industrial sectors and for the public community in general. The problem is usually approached by the use of functional coatings and most of such antifouling coatings rely on the effect of biocides. However, a substantial drawback is the poor control over the release of the biocide as well as its degradation in the paint. Encapsulation of the biocides in microcapsules is a promising approach that may overcome some of the problems associated with the more traditional ways of incorporating the antifouling agent into the formulation. In this review, we summarize more than a decade of microcapsule research from our lab as well as from other groups working on this topic. Focus will be on two coacervation-based encapsulation techniques; the internal phase separation method and the double emulsion method, which together enable the encapsulation of a broad spectrum of biocides with different physicochemical properties. The release of the biocide from core-shell particles and from encapsulated biocides in coatings is treated in detail. The release behaviour is interpreted in terms of the physicochemical properties of the core-shell particle and the coating matrix. In addition, special attention is given to the experimental release methodology and the implementation of proper diffusion models to describe the release. At the end of the review examples of antifouling properties of some coatings against common biofoulers are presented.
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| 23. |
- Bergek, Jonatan, 1984, et al.
(författare)
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Controlled release of a microencapsulated arduous semi-hydrophobic active from coatings: Superhydrophilic polyelectrolyte shells as globally rate-determining barriers
- 2016
-
Ingår i: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 225, s. 31-39
-
Tidskriftsartikel (refereegranskat)abstract
- Polymethylmethacrylate-based microcapsules containing the antimicrobial agent 2-n-octyl-4-isothiazolin-3-one (OIT) decorated by an anchored polyelectrolyte brush consisting of an amphiphilic diblock copolymer of polymethylmethacrylate-block-poly(sodium methacrylate) type have been formulated via a coacervation technique. The polyelectrolyte brush surface provided the microcapsule with a high and stable surface charge density. This enabled further surface modification of the colloidal particle with a thin and dense polyelectrolyte multilayer using the layer-by-layer technique. The addition of the highly charged and hydrophilic polyelectrolyte multilayer assembled on the microcapsule surface resulted in a considerable decrease of the release rate of the encapsulated OIT in aqueous suspension, corresponding to a 40 times reduction of the effective OIT diffusion coefficient in the polymethylmethacrylate matrix. Moreover, the release of encapsulated or freely dispersed OIT from coatings as a function of the matrix density was evaluated and analyzed within the framework of applied diffusion models. Encapsulation of OIT in polyelectrolyte multilayer composite microcapsules was found to significantly prolong the release and render the release rate more or less independent of the matrix density. In addition, the long-term antimicrobial properties of the coatings were evaluated in terms of their susceptibility for biofouling using the fungus and common biofouler Aspergillus niger as model organism. The results clearly demonstrated that the use of encapsulated OIT gave a significantly prolonged surface protection and allowed for the determination of the critical surface flux. The polyelectrolyte multilayer has therefore been recognized as the rate-determining barrier for OIT. The matrix density has a minor influence on the release rate of encapsulated OIT from these microcapsules and this concept may very well be expanded to cover a broad range of hydrophobic and semi-hydrophobic biocides.
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| 24. |
- Bergek, Jonatan, 1984, et al.
(författare)
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Controlled release of microencapsulated 2-n-octyl-4-isothiazolin-3-one from coatings: Effect of microscopic and macroscopic pores
- 2014
-
Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects. - : Elsevier BV. - 1873-4359 .- 0927-7757. ; 458:1, s. 155-167
-
Tidskriftsartikel (refereegranskat)abstract
- To keep a painted facade protected from mold and algae, anti-growth agents are mixed in the coating. These biocides are small molecules with a high diffusivity inside the soft polymeric coating matrix resulting in a premature loss of protection. A promising improvement can be achieved by encapsulation of the biocide in micro-sized containers and thereby reducing the release rate from the coating. In this study, the biocide 2-n-octyl-4-isothiazolin-3-one (OIT) has been encapsulated by various formulation routes and the release has been studied with regard to different conditions. It was found that an exceptionally low interfacial tension between OIT and water practically prevents any formulation of core-shell particles. However, polymeric monoliths of OIT and poly(methyl methacrylate) could be formulated by the internal phase separation method. OIT release studies from these microspheres revealed formulation-dependent microscopic porosity where the chosen evaporation path of volatile solvent significantly alters the diffusion coefficient of the biocide in the microsphere. Dense microstructure with low diffusivity was given when the poly(methyl methacrylate) was provided time or heat for complete polymer relaxation. The microscopic porosity was evaluated within a framework of applied diffusion models to the experimental data. In an applied perspective, microspheres could offer a value for sustained release of OIT from coatings. In this work, we found a considerable decrease in release rate from dry-film coatings with encapsulated OIT compared to freely dispersed OIT. In addition, macroscopic porosity in the coating, i.e. the porosity in the binder material, was proven to be crucial for the diffusivity. It was shown that macroscopic porosity heavily depends on the drying time of the coating where longer drying times of several weeks gave a substantial decrease in macroscopic porosity and release rate of OIT.
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| 25. |
- Borg, Markus, et al.
(författare)
-
Illuminating a Blind Spot in Digitalization - Software Development in Sweden's Private and Public Sector
- 2020
-
Ingår i: Proceedings - 2020 IEEE/ACM 42nd International Conference on Software Engineering Workshops, ICSEW 2020. - New York, NY, USA : Association for Computing Machinery, Inc. - 9781450379632 ; , s. 299-302
-
Konferensbidrag (refereegranskat)abstract
- As Netscape co-founder Marc Andreessen famously remarked in 2011, software is eating the world - becoming a pervasive invisible critical infrastructure. Data on the distribution of software use and development in society is scarce, but we compile results from two novel surveys to provide a fuller picture of the role software plays in the public and private sectors in Sweden, respectively. Three out of ten Swedish firms, across industry sectors, develop software in-house. The corresponding figure for Sweden's government agencies is four out of ten, i.e., the public sector should not be underestimated. The digitalization of society will continue, thus the demand for software developers will further increase. Many private firms report that the limited supply of software developers in Sweden is directly affecting their expansion plans. Based on our findings, we outline directions that need additional research to allow evidence-informed policy-making. We argue that such work should ideally be conducted by academic researchers and national statistics agencies in collaboration. © 2020 ACM.
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| 26. |
- Eriksson, Viktor, 1995, et al.
(författare)
-
A unified thermodynamic and kinetic approach for prediction of microcapsule morphologies
- 2024
-
Ingår i: Journal of Colloid and Interface Science. - 1095-7103 .- 0021-9797. ; 662, s. 572-582
-
Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: Microcapsule formation, following internal phase separation by solvent evaporation, is controlled by two main factors of thermodynamic and kinetic origin. Morphology prediction has previously focused on the final thermodynamical state in terms of spreading conditions, limiting the prediction accuracy. By additionally considering kinetic effects as the emulsion droplet evolves through the two-phase region of its ternary phase diagram during solvent evaporation, this should enhance prediction accuracy and explain a wider range of morphologies. Experiments: Dynamical interfacial tensions, and thereby spreading coefficients, during the formation of poly(methyl methacrylate) and poly(D,L-lactic-co-glycolic acid) microcapsules were measured by first establishing the boundaries and tie-lines of the ternary system in the emulsion droplets. Kinetic effects during the formation were investigated by varying the solvent evaporation rate and hence the time for polymer shell formation equilibration. The theory was validated by comparing predicted morphologies to microscopic snapshots of intermediate and final morphologies. Findings: The proposed theory explained both intermediate acorn and core–shell morphologies, where a late transition from acorn to core–shell produced microcapsules containing highly off-centered cores. By considering the kinetic factors, the formulation could be altered from yielding kinetically frozen acorns to core–shell and from yielding multicore to single core microcapsules.
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| 27. |
- Eriksson, Viktor, 1995, et al.
(författare)
-
Microcapsule functionalization enables rate-determining release from cellulose nonwovens for long-term performance
- 2023
-
Ingår i: Journal of Materials Chemistry B. - : Royal Society of Chemistry (RSC). - 2050-7518 .- 2050-750X. ; 11:12, s. 2693-2699
-
Tidskriftsartikel (refereegranskat)abstract
- Functional textiles is a rapidly growing product segment in which sustained release of actives often plays a key role. Failure to sustain the release results in costs due to premature loss of functionality and resource inefficiency. Conventional application methods such as impregnation lead to an excessive and uncontrolled release, which - for biocidal actives - results in environmental pollution. In this study, microcapsules are presented as a means of extending the release from textile materials. The hydrophobic model substance pyrene is encapsulated in poly(d,l-lactide-co-glycolide) microcapsules which subsequently are loaded into cellulose nonwovens using a solution blowing technique. The release of encapsulated pyrene is compared to that of two conventional functionalization methods: surface and bulk impregnation. The apparent diffusion coefficient is 100 times lower for encapsulated pyrene compared to impregnated pyrene. This clearly demonstrates the rate-limiting barrier properties added by the microcapsules, extending the potential functionality from hours to weeks.
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| 28. |
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| 29. |
- Grape, Sophie, 1982-, et al.
(författare)
-
Non-proliferation and safeguards activities within the Alva Myrdal Centre for nuclear disarmament
- 2022
-
Ingår i: Proceedings of the Symposium on International Safeguards: Reflecting on the Past and Anticipating the Future.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In 2020, the Swedish government announced the intent to start up a national competence centre on nuclear disarmament in Sweden. The goal was to highlight the importance of nuclear disarmament issues, and to promote research, teaching and policy support on topics relevant to nuclear disarmament. During the spring semester 2021, the Alva Myrdal Centre (AMC) on nuclear disarmament was established at Uppsala University. The AMC combines competences from different disciplines such as peace and conflict research, applied nuclear physics, and international law, and organises the work into six different working groups. One of the working groups is focusing on technical aspects, while the remaining five working groups are focusing on policy aspects. The technical working group is led by the Division of Applied Nuclear Physics at Uppsala University, where research on nuclear safeguards has been performed for over 30 years, and where competence in addition exists on a number of applied physics applications ranging from nuclear reactions, nuclear power and detection of radionuclides.
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| 30. |
- Grape, Sophie, 1982-, et al.
(författare)
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State-of-the-Art Report : Prepared by Working Group 4: Technical nuclear non-proliferation and safeguards under the Alva Myrdal Centre for nuclear disarmament
- 2022
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Alva Myrdal Centre for nuclear disarmament (AMC) was established in 2021. AMC consists of six working Groups, and one of them - Working Group 4 - is called Technical nuclear non-proliferation and safeguards. This is the State-of-the-Art Report of that working group. The objective with the report is to provide an overview of the technical fields relevant to the working group and to highlight where research and activities within the working group may contribute to global nuclear disarmament. The report gives a brief explanation of actors in the field, introduces nuclear materials and assay techniques, and then continues to elaborate on challenges and needs associated with nuclear measurements and assessments in the fields of non-proliferation, nuclear safeguards and nuclear disarmament. A section is also devoted to the management of nuclear weapons materials after disarmament. Lastly, the report contains a section on interdisciplinary research and development in nuclear disarmament, and information about technical education and training in the non-proliferation and disarmament field.
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| 31. |
- Gustavsson, Cecilia, Dr, 1973-, et al.
(författare)
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A technical view on Pakistan's nuclear weapons programme
- 2022
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Pakistan performed at least two nuclear weapons tests in 1998 as a direct response to the Indian nuclear tests earlier the same year. With this act, Pakistan became the seventh country to successfully complete a nuclear weapons programme. The Pakistani nuclear weapons arsenal consists of both uranium and plutonium weapons and the country has an extensive nuclear industry with all facilities necessary for enrichment of uranium, production of plutonium and reprocessing of spent reactor fuel.Pakistan acquired a Canadian civil heavy water nuclear reactor in 1971; KANUPP-1. In 1976 however, the cooperation with Canada ended as Canada stopped supplying fuel for the reactor. At this point, Pakistan had acquired know-how and experience to manufacture its own fuel and also started building an independent nuclear industry with several unsafeguarded reactors at the Khushab site. With French assistance, a reprocessing plant was constructed and consequently, Pakistan is today in possession of all components necessary for developing and employing both uranium and plutonium nuclear devices. In this presentation, we will explore technical challenges associated with bringing a country such as Pakistan under the existing or proposed treaty verification following treaties such as the NPT, TPNW and FMCT. Using a simulation framework and estimates based on known physical quantities and derived abilities, we will discuss what conclusions can be drawn with regards to uranium and plutonium stockpiles.
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| 32. |
- Hedin, Jesper, 1980, et al.
(författare)
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Bi-Layer Formation of Imidazole- Modified Ethyl(HydroxyEthyl)Cellulose at a Hydrophobic Surface as monitored by QCM-D
- 2009
-
Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 336:2, s. 388-392
-
Tidskriftsartikel (refereegranskat)abstract
- The adsorption behaviour of ethyl(hydroxyethyl)cellulose chemically modified with imidazole (Im-EHEC) at hydrophobic surfaces has been studied with QCM-D. The very slow adsorption isotherm was due to a continuous polymer film reconfiguration and exchange of different sized polymers. The thickness of the film was about 30 nm. The polymers adsorbed Cu2+ ions into the film from a CuCl2 solution and a bi-layer was formed when Im-EHEC was added a second time. The second polymer film was only 7 nm thick but highly viscoelastic. After rinsing with water the metal ions was flushed away and the second Im-EHEC layer was released. The imidazole modification of EHEC enables interaction with transition metal ions and opens up for new applications for cellulose based materials.
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| 33. |
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| 34. |
- Ma, Zaifei, et al.
(författare)
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Synthesis and characterization of benzodithiophene-isoindigo polymers for solar cells
- 2012
-
Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 1364-5501 .- 0959-9428. ; 22:5, s. 2306-2314
-
Tidskriftsartikel (refereegranskat)abstract
- Three new alternating polymers with the electron-deficient isoindigo group as the acceptor unit and benzo[1,2-b:4,5-b'] dithiophene (BDT) or BDT flanked by thiophenes (or octylthiophenes) as the donor unit were designed and synthesized. All the polymers have good thermal stability, solubility and broad absorption spectra. Their photophysical, electrochemical and photovoltaic (PV) properties were investigated. To understand their different PV performance in the resulting polymer solar cells (PSCs), the morphology of their blends with fullerene derivatives was investigated by atomic force microscopy, and the molecular geometries as well as the molecular frontier orbitals were simulated by density functional theory calculations (Gaussian 09). The polymer PBDT-TIT, with BDT flanked by thiophenes as the donor unit and isoindigo as the acceptor unit, exhibits quite planar backbones and its blend with fullerene derivatives shows optimal morphology. As a result, the PSCs based on PBDT-TIT with a conventional device configuration of ITO/PEDOT: PSS/PBDT-TIT: PC(61)BM/LiF/Al showed a power conversion efficiency of 4.22%, with a short-circuit current density of 7.87 mA cm(-2), an open-circuit voltage of 0.79 V and a fill factor of 0.68 under the AM 1.5G illumination with an intensity of 100 mW cm(-2) from a solar simulator.
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| 35. |
- Taube, Magdalena, et al.
(författare)
-
Evaluation of reference genes for gene expression studies in human brown adipose tissue.
- 2015
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Ingår i: Adipocyte. - : Informa UK Limited. - 2162-3945 .- 2162-397X. ; 4:4, s. 280-5
-
Tidskriftsartikel (refereegranskat)abstract
- Human brown adipose tissue (BAT) has during the last 5 year been subjected to an increasing research interest, due to its putative function as a target for future obesity treatments. The most commonly used method for molecular studies of human BAT is the quantitative polymerase chain reaction (qPCR). This method requires normalization to a reference gene (genes with uniform expression under different experimental conditions, e.g. similar expression levels between human BAT and WAT), but so far no evaluation of reference genes for human BAT has been performed. Two different microarray datasets with samples containing human BAT were used to search for genes with low variability in expression levels. Seven genes (FAM96B, GNB1, GNB2, HUWE1, PSMB2, RING1 and TPT1) identified by microarray analysis, and 8 commonly used reference genes (18S, B2M, GAPDH, LRP10, PPIA, RPLP0, UBC, and YWHAZ) were selected and further analyzed by quantitative PCR in both BAT containing perirenal adipose tissue and subcutaneous adipose tissue. Results were analyzed using 2 different algorithms (Normfinder and geNorm). Most of the commonly used reference genes displayed acceptably low variability (geNorm M-values <0.5) in the samples analyzed, but the novel reference genes identified by microarray displayed an even lower variability (M-values <0.25). Our data suggests that PSMB2, GNB2 and GNB1 are suitable novel reference genes for qPCR analysis of human BAT and we recommend that they are included in future gene expression studies of human BAT.
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| 36. |
- Yang Nilsson, Ting, et al.
(författare)
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A solution blown superporous nonwoven hydrogel based on hydroxypropyl cellulose
- 2020
-
Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-6848 .- 1744-683X. ; 16:29, s. 6850-6861
-
Tidskriftsartikel (refereegranskat)abstract
- A superporous hydrogel - in which the interconnecting fibres themselves are hydrogels - based on hydroxypropyl cellulose (HPC) has been produced using the nonwoven solution blown technique. The nonwoven fibres were subsequently thermally crosslinked with citric acid as identified by esterbond formation using FT-IR spectroscopy. The gel fraction was approximately 70%. The superporous HPC hydrogel exhibited a very fast water absorption, reaching an equilibrium absorption (80% water content) within 30 seconds. The equilibrium absorption was strongly codependent on both the fibre thickness and the pore size whereas the absorption rate was correlated with the pore size as established using standard linearized regression analysis.
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| 37. |
- Zhuang, Wenliu, 1979, et al.
(författare)
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Influence of Incorporating Different Electron-Rich Thiophene-Based Units on the Photovoltaic Properties of Isoindigo-Based Conjugated Polymers: An Experimental and DFT Study
- 2013
-
Ingår i: Macromolecules. - : American Chemical Society (ACS). - 1520-5835 .- 0024-9297. ; 46:21, s. 8488-8499
-
Tidskriftsartikel (refereegranskat)abstract
- A series of novel donor–acceptor conjugated alternating copolymers based on the isoindigo acceptor moiety have been designed, synthesized, and characterized, in order to explore the potential of isoindigo for efficient donor materials with high photovoltages in solar cells. We have systematically investigated and discussed the effect of combining different electron-rich thiophene-based units on the structural, optical, electronic, and photovoltaic properties of the resulting polymers. Morphological studies and quantum-chemical calculations are carried out to gain insights into the different properties. The power conversion efficiencies (PCEs) of the solar cells based on these polymers are increased step by step by over 3-fold through a rational structural modification. Among them, PBDTA-MIM shows a PCE of 5.4%, which is to our knowledge the best result achieved among isoindigo-based polymers for solar cells combined with PC61BM as the acceptor using the conventional device configuration. Our results further emphasize the use of isoindigo as an effective acceptor unit and highlight the importance of carefully choosing appropriate chemical structure to design efficient donor–acceptor polymers for organic solar cells. In addition, the resulting low optical gaps, the promising PCEs with PC61BM as the acceptor, and the good open-circuit voltages (up to 0.8 V) synergistically demonstrate the potential of this class of polymers as donor materials for bottom subcells in organic tandem solar cells.
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