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Östermalm, Sweden

Zhu C.,Lulea University of Technology | Dobryden I.,Lulea University of Technology | Ryden J.,Lulea University of Technology | Oberg S.,Lulea University of Technology | And 3 more authors.
Langmuir | Year: 2015

The aim of this study was to develop a fundamental understanding of the adsorption behavior of metal ions on cellulose surfaces using experimental techniques supported by computational modeling, taking Ag(I) as an example. Force interactions among three types of cellulose microspheres (native cellulose and its derivatives with sulfate and phosphate groups) and the silica surface in AgNO3 solution were studied with atomic force microscopy (AFM) using the colloidal probe technique. The adhesion force between phosphate cellulose microspheres (PCM) and the silica surface in the aqueous AgNO3 medium increased significantly with increasing pH while the adhesion force slightly decreased for sulfate cellulose microspheres (SCM), and no clear adhesion force was observed for native cellulose microspheres (CM). The stronger adhesion enhancement for the PCM system is mainly attributed to the electrostatic attraction between Ag(I) and the negative silica surface. The observed force trends were in good agreement with the measured zeta potentials. The scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) analyses confirmed the presence of silver on the surface of cellulose microspheres after adsorption. This study showed that PCM with a high content of phosphate groups exhibited a larger amount of adsorbed Ag(I) than CM and SCM and possible clustering of Ag(I) to nanoparticles. The presence of the phosphate group and a wavenumber shift of the P-OH vibration caused by the adsorption of silver ions on the phosphate groups were further confirmed with computational studies using density functional theory (DFT), which gives support to the above findings regarding the adsorption and clustering of Ag(I) on the cellulose surface decorated with phosphate groups as well as IR spectra. © 2015 American Chemical Society. Source

Dabrowska-Kloda K.,County Hospital of Varmland | Kloda T.,Stockholm UniversityStockholm | Boudiaf S.,County Hospital of Varmland | Jakobsson G.,Sahlgren University Hospital | Stenevi U.,Sahlgren University Hospital
Journal of Cataract and Refractive Surgery | Year: 2015

Purpose To identify risk factors for late in-the-bag intraocular lens (IOL) dislocation and estimate the incidence of this condition over a 21-year period. Setting Department of Ophthalmology, County Hospital of Värmland, Karlstad, Sweden. Design Retrospective cohort study and nested case-control study. Methods The medical records of eyes operated on for late in-the-bag IOL dislocation between 1992 and 2012 were reviewed. The annual incidence and cumulative risk were calculated. Results Of 140 eyes whose records were reviewed, 123 qualified for comparison (24 variables) with an equal number in a control group. The annual incidence varied between 0.00% and 0.08%. An increasing trend was found (P <.001). The cumulative risk 5, 10, 15, and 20 years after cataract extraction was 0.09%, 0.55%, 1.00%, and 1.00%, respectively, and was significantly higher (P < .001) in eyes that had cataract surgery between 2002 and 2012 than in those operated on between 1992 and 2001 (0.89% versus 0.39% at 10 years postoperatively) (P <.001). Calendar time (date) of dislocation was positively correlated with the duration of preceding pseudophakia (P = .005). Phacoemulsification time was longer in eyes with dislocation than in control eyes (P <.001). Other identified risk factors were pseudoexfoliation, zonular dehiscence, pseudophacodonesis, and increased axial length. Conclusions The increasing number of late in-the-bag IOL dislocations cannot be explained by the growing pseudophakic population only. The increase in the incidence was due primarily to the longer duration of pseudophakia in the population and to a greater dislocation risk with recent cataract surgery. The increase in life expectancy played a minor role. Long phacoemulsification time was a risk factor for dislocation. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned. © 2015 ASCRS and ESCRS. Source

Eklund L.,Stockholm UniversityStockholm
Computers in Human Behavior | Year: 2015

Studies of virtual worlds are often based on the dichotomous 'real world'/'virtual world', yet research has indicated that this division is far from unproblematic. The aim of this study is to examine empirically the link between online/offline using the example of social online gaming. The data consist of individual and group interviews with 33 adult gamers. The results explore three themes - sociability and design; group membership; norms and rules - and show how on-and offline are inexorably linked through the social organizational demands of Internet gaming. Individuals ground online group membership in offline relations and shared characteristics, aiming to maximize game-play gains and support sociability. Gaming with 'people like us' facilitates creation of norms and expectations, which aids in producing stable social groups. Thus the boundary between online and offline becomes contingent on links between people. The study shows how important offline connections are for online interaction. © 2015 Elsevier Ltd. Source

Brandt E.G.,Stockholm UniversityStockholm | Lyubartsev A.P.,Stockholm UniversityStockholm
Journal of Physical Chemistry C | Year: 2015

Atomistic force field parameters were developed for the TiO2-water interface by systematic optimization with respect to experimentally determined crystal structures (lattice parameters) and surface thermodynamics (water adsorption enthalpy). Optimized force field parameters were determined for the two cases where TiO2 was modeled with or without covalent bonding. The nonbonded TiO2 model can be used to simulate different TiO2 phases, while the bonded TiO2 model is particularly useful for simulations of nanosized TiO2 and biomatter, including protein-surface and nanoparticle-biomembrane simulations. The procedure is easily generalized to parametrize interactions between other inorganic surfaces and biomolecules. © 2015 American Chemical Society. Source

Heydari H.,Stockholm UniversityStockholm | Andersson O.,Stockholm UniversityStockholm
Physica Scripta | Year: 2015

Geometrical structures of quantum mechanics provide us with new insightful results about the nature of quantum theory. In this work we consider mixed quantum states represented by finite rank density operators. We review our geometrical framework that provide the space of density operators with Riemannian and symplectic structures, and we derive a geometric uncertainty relation for observables acting on mixed quantum states. We also give an example that visualizes the geometric uncertainty relation for spin-1/2 particles. © 2015 The Royal Swedish Academy of Sciences. Source

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