| 1. |
- Damberg, Mattias, et al.
(författare)
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Investigation of transcription factor AP-2 beta genotype in women with premenstrual dysphoric disorder.
- 2005
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Ingår i: Neuroscience letters. - : Elsevier BV. - 0304-3940. ; 377:1, s. 49-52
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Tidskriftsartikel (refereegranskat)abstract
- It has repeatedly been shown that the serotonergic system is involved in the symptomatology of premenstrual dysphoric disorder (PMDD). Women with PMDD are reported to differ from symptom-free controls with regard to serotonin-related biological markers. Evidence from family and twin studies suggests a genetic contribution to the aetiology of PMDD. The expression of human transcription factor AP-2beta in neural crest cell lineages and neuroectodermal cells suggests that this protein may be of importance for functional characteristics of neurons by regulating the expression of target genes. Within the monoaminergic systems, several genes have binding sites for AP-2beta in regulatory regions, suggesting an involvement of AP-2beta in these systems. The gene encoding AP-2beta is located on chromosome 6p12-p21.1 and includes a polymorphic region consisting of a variable number of [CAAA] repeats located in the second intron. We have earlier shown that AP-2beta genotype is associated with serotonergic phenotypes and that brainstem levels of AP-2beta correlate positively to serotonin metabolism in rat frontal cortex. The aim of this study was to investigate the relationship between PMDD and transcription factor AP-2beta genotype. The participants included 176 women with PMDD and 91 healthy controls. Genotyping was performed by polymerase chain reactions. We did not observe any differences in AP-2beta genotype frequencies between PMDD subjects and controls. Our results suggest that AP-2beta genotype is not a risk factor for PMDD. To our knowledge, this is the first study investigating transcription factor AP-2beta genotype in women with PMDD. Hence, these results should be considered preliminary until replicated.
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| 2. |
- Eriksson, Olle, 1954-, et al.
(författare)
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Ovarian morphology in premenstrual dysphoria
- 2012
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Ingår i: Psychoneuroendocrinology. - : Elsevier BV. - 0306-4530 .- 1873-3360. ; 37:6, s. 742-751
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Tidskriftsartikel (refereegranskat)abstract
- Ovarian cyclicity is a prerequisite for premenstrual dysphoria (PMD), as illustrated by the fact that this condition is effectively eliminated by ovariectomy or by treatment with a GnRH agonist. Despite the possibility of differences in ovarian function between women with and without PMD, no study comparing ovarian morphology in these two groups has ever been published. Fifty-two women were recruited for this study; 26 had premenstrual dysphoria, fulfilling criteria slightly modified from those of the premenstrual dysphoric disorder, and 26 were asymptomatic age-matched controls. Ovarian morphology was assessed using transvaginal 7MHz ultrasonography on day 5 after the start of menses, and venous blood was sampled for hormone analysis on days 3 and 8, the expected day of ovulation, and day -4 of the menstrual cycle. There were no significant differences between the groups with respect to the prevalence of polycystic ovaries (PCO), the total number of follicles, the total ovarian volume or serum levels of androgen hormones. In addition, serum free testosterone levels in late premenstrual phase showed an inverse association to premenstrual symptoms of irritability and a similar inverse association trend to symptoms of depressed mood. Unexpectedly, the prevalence of ovaries with fewer than five antral or growing follicles was significantly higher in women with PMD than in controls (p=0.016). While the results do not support a role for PCO or androgen hormones in eliciting late luteal phase irritability, the possible relationship between oligofollicular ovaries and PMD deserves further study.
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| 3. |
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| 4. |
- Bijelovic, Stojanka, et al.
(författare)
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Wear-resistant magnetic thin film material based on a Ti1−xFexC1−y nanocomposite alloy
- 2010
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Ingår i: Physical Review B Condensed Matter. - : The American Physical Society. - 0163-1829 .- 1095-3795. ; 81:1, s. 014405-
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Tidskriftsartikel (refereegranskat)abstract
- In this study we report on the film growth and characterization of thin films deposited on amorphous quartz. The experimental studies have been complemented by first-principles density-functional theory metastable Ti-Fe-C film changes. With increasing annealing time, there is a depletion of iron close to the surface of the film, while regions enriched in iron are simultaneously formed deeper into the film. Both the magnetic ordering temperature and the saturation magnetization changes significantly upon annealing. The DFT calculations show that the critical temperature and the magnetic moment both increase with increasing Fe and C-vacancy concentration. The formation of the metastable iron-rich Ti-Fe-C compound is reflected in the strong increase in the magnetic ordering temperature. Eventually, after enough annealing time nanocrystalline -Fe starts to precipitate, the amount and size of which can be controlled by the annealing procedure; after 20 min of annealing, the experimental results indicate a nanocrystalline iron-film embedded in a wear-resistant TiC compound. This conclusion is further supported by transmission electron microscopy studies on epitaxial Ti-Fe-C films deposited on single-crystalline MgO substrates where, upon annealing, an iron film embedded in TiC is formed. Our results suggest that annealing of metastable Ti-Fe-C films can be used as an efficient way of creating a wear-resistant magnetic thin film material. approximately 50-nm-thick Ti-Fe-CDFT calculations. Upon annealing of as-prepared films, the composition of the10 min, nanocrystalline -Fe starts to precipitate, the amount and size of which can be controlled by the annealing procedure; after 20 min of annealing, the experimental results indicate a nanocrystalline iron-film embedded in a wear-resistant TiC compound. This conclusion is further supported by transmission electron microscopy studies on epitaxial Ti-Fe-C films deposited on single-crystalline MgO substrates where, upon annealing, an iron film embedded in TiC is formed. Our results suggest that annealing of metastable Ti-Fe-C films can be used as an efficient way of creating a wear-resistant magnetic thin film material.
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| 5. |
- Jansson, Ulf, et al.
(författare)
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Design of carbide-based nanocomposite thin films by selective alloying
- 2011
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 206:4, s. 583-590
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Tidskriftsartikel (refereegranskat)abstract
- This paper reviews a series of studies on alloying of sputtered TiC coatings with weak carbide-forming metals, Me, such as Al, Fe, Ni, Pt and Cu. Metastable solid solutions with Me on the Ti sites are easily obtained by magnetron sputtering at low temperatures (< 300 °C). First principles density functional theory (DFT) calculations of such carbides show that a driving force exists to remove carbon from the structure as an alternative and kinetically more favourable route compared to Me precipitation. This leads to a situation where additional control of the phase composition is given by annealing: both direct influence during film growth, as well as through subsequent annealing. Thus, alloying of the nanocomposite with weak carbide-forming metals can be used to tune many mechanical, electric and magnetic properties of a carbide-based nanocomposite film.
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| 6. |
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| 7. |
- Lewin, Erik, et al.
(författare)
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Design of the Lattice Parameter of Embedded Nanoparticles
- 2010
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 496:1-3, s. 95-99
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Tidskriftsartikel (refereegranskat)abstract
- It is found that the bonding of nanoparticles in nancomposites can be influenced by interactions with a surrounding matrix phase. A model involving charge transfer between phases is presented, and supported by DFT-simulations. The model explains observations in nanocomposite nc-TiCx/a-C of additional interface states and lattice expansion of TiCx. It is suggested that this approach can be extended to other types of nanocomposites, and that it opens for new possibilities in materials design.
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| 8. |
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| 9. |
- Råsander, Mikael, 1979-
(författare)
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A Theoretical Perspective on the Chemical Bonding and Structure of Transition Metal Carbides and Multilayers
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present thesis deals with a theoretical description of issues regarding chemical bonding, structure and stability of transition metal carbides and multilayered structures. First principles density functional theory has been used extensively to investigate the properties of alloyed solutions of transition metal carbides. Joint theoretical and experimental investigations have shown that there is a driving force for carbon to be released from these ternary carbide systems as a response to the alloying. This release of carbon was shown to yield favorable lubricating properties in the case of alloyed solutions of Ti-Al-C, that were not present in the case of pure TiC, a property that can be used to design new materials that combine high hardness with favorable tribological properties. From calculations of the activation energy of C diffusion in the vicinity of substitutional transition metal impurities (M) in TiC, it is found that the mobility of C atoms is increased due to the presence of the impurities. The lowering of the activation energy barriers suggests that the mobility of C in alloyed solutions of Ti-M-C is increased and will be more pronounced at lower temperature than for C diffusion in TiC. The magnetic properties of alloyed solutions of Ti-Fe-C has been investigated using both theory and experiment. Theoretical calculations reveal that the magnetic moment and the critical temperature increase when increasing the Fe content as well as when lowering the C content in the system. Furthermore, the magnetic exchange parameters between Fe atoms were found to clearly reflect changes in the chemical bonding when varying the C content. Experimentally the magnetic properties were found to be rather substantial. Furthermore, the magnetic properties changes upon annealing due to the formation of Fe-rich and Fe-poor regions in the system. After long enough annealing times precipitates of α-Fe are formed which is consistent with theoretical predictions. The interaction between TiC(111) surfaces and C in the form of graphite has also been investigated. For these systems it was found that graphite was rather strongly bonded to the carbide surface and that the atomic as well as electronic structure at the interface depend on the termination of the carbide surface. This research was motivated by the recent interest in graphene, but also to investigate how carbide grains interacts with C when dispersed in a carbon matrix. A model for the calculation of structural parameters in multilayer structures has been presented and evaluated. The model is based on classical elasticity theory and uses the elastic constants of the materials constituting the multilayer as the only input.
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| 10. |
- Råsander, Mikael, et al.
(författare)
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Carbon Release by Selective Alloying of Transition Metal Carbides
- 2011
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 23:35, s. 355401-
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Tidskriftsartikel (refereegranskat)abstract
- We have performed first principles density functional theory calculations on TiC alloyed on the Ti sublattice with 3d transition metals ranging from Sc to Zn. The theory is accompanied by experimental investigations, both as regards materials synthesis as well as characterization. Our results show that by dissolving a metal with a weak ability to form carbides, the stability of the alloy is lowered and a driving force for the release of carbon from the carbide is created. During thin film growth of a metal carbide this effect will favour the formation of a nanocomposite with carbide grains in a carbon matrix. The choice of alloying element as well as its concentration will affect the relative amount of carbon in the carbide and in the carbon matrix. This can be used to design the structures of nanocomposites and their physical and chemical properties. One example of applications is as low-friction coatings. Of the materials studied, we suggest the late 3d transition metals as the most promising elements for this phenomenon, at least when alloying with TiC.
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