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| 2. |
- Barkarmo, Sargon, et al.
(författare)
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Nano-hydroxyapatite-coated PEEK implants : a pilot study in rabbit bone
- 2013
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Ingår i: Journal of Biomedical Materials Research. Part A. - : John Wiley & Sons. - 1549-3296 .- 1552-4965. ; 101A:2, s. 465-471
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Tidskriftsartikel (refereegranskat)abstract
- Osseointegration of surface-modified polyetheretherketone (PEEK) implants was studied in vivo. A total of 18 cylinder-shaped PEEK implants were inserted in the femurs of nine New Zealand rabbits; half were coated with nanocrystalline hydroxyapatite (nanoHA) and half were uncoated controls. Healing time was 6 weeks. Samples were retrieved with the implant and surrounding tissue, processed to cut and ground sections, and analyzed histomorphometrically. The implant surfaces were analyzed with optical interferometry, scanning electron microscopy (SEM), atomic force microscopy, and X-ray photoelectron spectroscopy (XPS). NanoHA-coated PEEK surfaces had lower height deviation (Sa) than controls [mean ± SD: 0.41 μm (± 0.14) vs. 0.96 μm (± 0.28)]. SEM images showed the nanoHA crystals as a thin layer on the polymer surface. XPS analysis of the coated implants showed a Ca/P ratio of 1.67. Histomorphometry indicated that the nanoHA-coated implants had more bone-to-implant contact [16% (± 4.7) vs. 13% (± 9.3)] and more bone area [52% (± 9.5) vs. 45% (± 11.9)]. We found no difference between smooth nanoHA-coated cylinder-shaped PEEK implants and uncoated controls. However, higher mean bone-to-implant contact indicated better osseointegration in the coated implants than in the uncoated controls. The large number of lost implants was interpreted as a lack of primary stability due to implant design.
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| 3. |
- Borel, Cédric, 1979, et al.
(författare)
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Family of Isoreticular Chiral Metal-Organic Frameworks Based on Coordination and Hydrogen Bonds in [M[Co(ethylenediamine)(oxalato)2]2]
- 2010
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 10:4, s. 1971-1978
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Tidskriftsartikel (refereegranskat)abstract
- From the parent compound [Ca[Co(ethylenediamine)(oxalato)2]2]n . 4H2O, 1, a series of framework compounds was prepared via the soluble sodium salt and crystal growth with the divalent metal ions Cd2+, Mn2+, and Sr2+, (2-4). These compounds have the same general formula [M[Co(ethylenediamine)(oxalato)2]2]n . xH2O, and they all form the same four- and eight-connected 3D net having scu topology (and are thus isoreticular) with water filled channels of variable size running in one direction of the crystals. However, they crystallize in two different space groups, the chiral P21) (3, 4, and the low temperature form of 1) and the noncentrosymmetric P-4 (1 and 2). The potential voids upon water removal are 18-20% of the unit cell. Preliminary gas sorption measurements at 298 K and 8 bar show substantial CO2 and N2O uptake (12-14% and 15-16% by mass, respectively), while the H2 uptake was 0.18%, a relatively high value considering the low pressure and high temperature.
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| 4. |
- Fant, Camilla, 1974, et al.
(författare)
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Complexation Chemistry for Tuning Release from Polymer Coatings
- 2006
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 110:43, s. 21808-21815
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Tidskriftsartikel (refereegranskat)abstract
- The strategy of metal ion complexation is employed to design a delivery system for an antifouling agent (AFA) in marine paints. A poly(1-vinylimidazole- co-methyl methacrylate) copolymer (PVM), together with Cu 2+ or Zn 2+ formed a PVM-M 2+ complex. The AFA, Medetomidine, was then coordinated into the complex. The coordination strength was investigated in solution by 1 H NMR and on solid surfaces by using the Quartz Crystal Microbalance with Dissipation monitoring technique (QCM-D) and Surface Plasmon Resonance (SPR). From the 1 H NMR experiments strong interactions were observed between Cu 2+ and the PVM-polymer and between Medetomidine and the PYM-Cu 2+ complex. From the QCM-D and SPR measurements it was shown that Cu 2+ , compared to Zn 2+ , exhibited a larger affinity for the PVM-copolymer surface that resulted in higher degree of swelling of the polymer film. Large amounts of Medetomidine were adsorbed to the PVM-Cu 2+ complex resulting in low desorption rates. However, the adsorbed amount of Medetomidine was lowerto the Zn 2+ doped polymer and a higher desorption rate was observed. These results indicate the possibility of tuning the release of Medetomidine by altering the coordinating metal ion, which may prove to be favorable in a paint formulation. © 2006 American Chemical Society.
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| 5. |
- HANDA, PAUL, 1980, et al.
(författare)
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1,4-conjugate addition reaction catalyzed by a homogeneous rhodium catalyst entrapped in hydrophobized ordered mesoporous silica
- 2008
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Ingår i: Microporous and Mesoporous Materials. - : Elsevier BV. - 1387-1811. ; 116:1-3, s. 424-431
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Tidskriftsartikel (refereegranskat)abstract
- A 1,4-conjugate addition reaction between p-carboxyphenylboronic acid and methyl acrylate has been performed using a homogenous rhodium catalyst entrapped in the hydrophobic pores of hydrophobized ordered mesoporous silica. The catalyst-loaded inorganic particles were dispersed in an aqueous solution containing the reactants. The yields obtained were higher than that obtained in the conventional liquid-liquid two-phase system. From the recycling experiments it was demonstrated that with hydrophobized ordered mesoporous silica as support a catalytic activity extending over several consecutive runs compared to the liquid-liquid two-phase system could be obtained. The major advantage with having the catalyst "heterogenized" by entrapment into the siliceous material is the simplicity of the work-up process. The porous particles, containing the catalyst, are simply removed by filtration after completed reaction and the product precipitated from water upon acidification.
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| 6. |
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| 7. |
- HANDA, PAUL, 1980, et al.
(författare)
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Antifouling Agent Release from Marine Coatings - Ion Pair Formation/Dissolution for Controlled Release
- 2006
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Ingår i: Progress in Organic Coatings. - : Elsevier BV. - 0300-9440. ; 57:4, s. 376-382
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Tidskriftsartikel (refereegranskat)abstract
- In marine coatings, the ability to sustain constant release of antifouling agents (AFA(s)) over a long period of time has become increasingly important. One efficient approach to prevent that diffusion depletes the paint film's antifouling activity is to adsorb the AFA strongly to a specie with low translational mobility, such as a high molecular weight polymer. Therefore, the AFA, Medetomidine, was adsorbed onto a sulfonated polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SDPS) generating a Medetomidine-SDPS ion pair in an organic solvent. The interaction was investigated by 1 H NMR in butanol (BuOH-d 10 ) and on solid surfaces by the quartz crystal microbalance with dissipation monitoring technique (QCM-D) in two different solvents, seawater and o-xylene. From the NMR studies in butanol (BuOH-d 10 ), a strong interaction between Medetomidine and SDPS was observed. From the QCM-D measurements, differences in affinity between Medetomidine and the SDPS was observed when changing from seawater to o-xylene. In seawater, the interaction was weak and displayed a large degree of reversibility compared to in o-xylene, where the interaction was strong and almost irreversible. Different swelling behaviour was also observed at the solid surfaces depending on the solvent used with o-xylene exhibiting the largest swelling of the polymer layer. © 2006 Elsevier B.V. All rights reserved.
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| 10. |
- HANDA, PAUL, 1980, et al.
(författare)
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The Sonogashira reaction catalyzed by palladium leached from ordered mesoporous carbon
- 2009
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Ingår i: Microporous and Mesoporous Materials. - 1387-1811. ; 117, s. 126-135
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Tidskriftsartikel (refereegranskat)abstract
- The Sonogashira carbon–carbon coupling reaction between iodobenzene and phenylacetylene was performed using palladium nanoparticles formed directly inside the pores of ordered mesoporous carbon as catalyst. The nanoparticles were generated by two methods, a phase-transfer method and a microemulsion procedure. The coupling reaction was performed using different bases and varying amounts of palladium and the yields and reaction profiles were determined by 1H NMR. Recycling experiments were also performed and the recyclability was found to be very dependent on the choice of base. From the so-called Maitlis’ filtration test it was shown that soluble palladium species were present in solution and these were found to be active in catalyzing the coupling reaction. The degree of leaching depended on the type of base used. The results hint at the Sonogashira reaction being an example of homogeneous rather than heterogeneous catalysis, as has recently been suggested by other authors as well.
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