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| 6. |
- Björklund, RB, et al.
(author)
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Partial Reduction of a Vanadia/Silica-Titania Catalyst with NH3 + NO at 473 K Studied by Electrical Conductance and ESR Measurements
- 1992
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In: Journal of Physical Chemistry. - : American Chemical Society (ACS). - 0022-3654 .- 1541-5740. ; 96:26, s. 10953-10959
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Journal article (peer-reviewed)abstract
- Partial reduction of vanadia supported on silica-titania by NH3 + NO has been studied by electrical conductance and ESR measurements. The relationship between electrical conductance and degree of reduction was determined by oxidative and reductive titrations of V(IV) and V(V) species leached from catalyst samples which had been reduced to different levels. In situ monitoring of the steady-state V(IV) ion concentration by electrical conductance during reduction with NH3 + NO in the concentration range 0-600 ppm for each reactant in a 2 vol % O2/Ar carrier gas was performed. In a large excess of NH3, the V(IV) ion concentration increased sharply with even small additions of NO. In a large excess of NO, the NH3 + NO mixture exhibited first an oxidizing character, and the V(IV) ion concentration increased when P(NH3) > 1/6P(NO). The reaction order with respect to the NO concentration, determined from both the NO conversion and the initial rate of catalyst reduction in excess NH3, was found to be less than unity. Determination of the stoichiometry of the reaction with respect to O2 indicated that the gas-phase O2 concentration required to balance the reducing character of NH3 + NO mixtures on the surface was significantly higher than predicted by the balanced equation describing the reaction. ESR measurements on the catalyst detected V(IV) ions as vanadyl groups having two different coordination spheres. Reduction of the catalyst with NH3 + NO caused an increase in the V(IV) signal and a decrease of the hyperfine structure.
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| 8. |
- Jonsdottir, Ingibjörg H, 1966, et al.
(author)
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Somatic nerve stimulation and cholera-induced net fluid secretion in the small intestine of the rat: evidence for an opioid effect.
- 1999
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In: Journal of the autonomic nervous system. - 0165-1838. ; 78:1, s. 18-23
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Journal article (peer-reviewed)abstract
- The effects of somatic nerve stimulation on cholera toxin induced secretion was investigated in vivo in anaesthetised rats. Small intestinal secretion was induced with cholera toxin and measured by a gravimetric technique. Afferent stimulation (pulse frequency within train; 100 Hz; train duration: 50 ms; train frequency: 3 Hz) of the sciatic nerve over 30 min significantly reduced the net fluid secretion both during (P < 0.05) and after cessation of the stimulation (P < 0.01). The greatest effect was obtained immediately after the termination of the nerve stimulation when the secretion was reversed to net fluid absorption. The opioid receptor antagonist naloxone (10 mg kg(-1) i.v.) administrated during the stimulation, significantly inhibited the antisecretory effect seen after the stimulation, thus no significant difference was seen between the control period and the periods after cessation of the stimulation. The opioid receptor antagonist naloxone methiodide (10 mg kg(-1) i.v.), which does not cross the blood-brain barrier, partly inhibited the antisecretory effects but not with the same magnitude as naloxone, thus the net fluid secretion was still significantly inhibited after the stimulation (P < 0.05). We conclude that afferent stimulation of the sciatic nerve strongly inhibits the cholera toxin induced secretion in the small intestine. This inhibition involves primarily a central opioid mechanism and to a lesser extent peripheral opioid mechanism.
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| 9. |
- Landtblom, Anne-Marie, 1953-, et al.
(author)
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Hypointensity in T2-weighted images of the basal ganglia in solvent-exposed patients with multiple sclerosis : Clinical, MRI and CSF characteristics
- 2003
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In: Neurological Sciences. - : Springer Science and Business Media LLC. - 1590-1874 .- 1590-3478. ; 24:1
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Journal article (peer-reviewed)abstract
- Several studies have indicated an association between MS and organic solvent exposure. Our objective was to analyse differences regarding cerebrospinal fluid (CSF) properties, magnetic resonance imaging (MRI) features and cerebral metabolites, measured by proton spectroscopy (1H-MRS), in 20 patients with spontaneous multiple sclerosis (MS) and in 20 patients with MS after solvent exposure, 15 healthy subjects served as controls. CSF examinations were retrospectively reviewed from the medical files. There were no significant differences in the CSF regarding pleocytosis, spinal-serum albumin ratio or mean extended IgG index. However, T2-weighted images of the solvent-exposed MS patients showed more hypointense areas in the basal ganglia. Hypointensity on T2-weighted images of the basal ganglia in the solvent-exposed MS patients may correspond to neurodegeneration and could be an early event in MS.
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| 10. |
- Lok, Veeleah, et al.
(author)
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Changes in anxiety and depression during the COVID-19 pandemic in the European population : A meta-analysis of changes and associations with restriction policies
- 2023
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In: European psychiatry. - 0924-9338 .- 1778-3585. ; 66:1
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Research review (peer-reviewed)abstract
- Background. Early studies of common mental disorders (CMDs) during the COVID-19 pandemic mainly report increases; however, more recent findings have been mixed. Also, studies assessing the effects of restriction measures on CMDs show varied results. The aim of this meta-analysis was to assess changes in levels of CMDs from pre-/early to during the pandemic and the effects of restriction policies in the European population.Methods. We searched for studies assessing both pre-pandemic and peri-pandemic self-reported emotional distress and symptoms of depression or anxiety among nationally/regionally representative samples in Europe and collected microdata from those studies. Estimates of corona containment index were related to changes in CMDs using random-effects meta-regression.Results. Our search strategy resulted in findings from 15 datasets drawn from 8 European countries being included in the meta-analysis. There was no evidence of change in the prevalence of emotional distress, anxiety, or depression from before to during the pandemic; but from early pandemic periods to later periods, there were significant decreases in emotional distress and anxiety. Increased school restrictions and social distancing were associated with small increases in self-reported emotional distress.Conclusions. Despite initial concerns of increased emotional distress and mental illness due to the COVID-19 pandemic, the results from this meta-analysis indicate that there was a decrease in emotional distress and no change in anxiety or depression in the general population in Europe. Overall, our findings support the importance of strong governance when implementing periodic and robust restriction measures to combat the spread of COVID-19.
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- Sjöqvist, Axel S.L. 1990, et al.
(author)
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Geochronology of the Norra Kärr alkaline complex, southern Sweden
- 2014
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In: 31st Nordic Geological Winter Meeting.
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Conference paper (other academic/artistic)abstract
- The Norra Kärr alkaline complex is a small intrusion of agpaitic nepheline syenite, located approximately 10 km north of Grän- na, southern Sweden, that is being explored for REE and Zr. Agpaitic nepheline syenites per definition do not contain simple Zr minerals like zircon and baddeleyite, despite generally high Zr contents (up to 1–2 wt.% ZrO2). Instead, Zr is mainly hosted in rock-forming complex Na-Ca-Zr silicate minerals such as members of the catapleiite, eudialyte, rosenbuschite, and wöhlerite groups. U-Pb zircon geochronology is thus highly impeded by the agpaitic nature. We established a new, reliable igneous age for the Norra Kärr alkaline complex at 1489±8 Ma (MSWD = 0.95) by dating zircons (U-Pb) in the country rocks that were affected by the magmatism-related alkaline alteration (fenitisation) by LA-MC-ICP-MS. Zircons from a satellite body of non-agpaitic syenite gave intercept ages within error of the age of fenitisation. This is an improvement upon an imprecise whole-rock Rb-Sr age of 1545±61 Ma (Blaxland 1977; Welin 1980). The non-fenitised country granite itself is dated at 1781±8 Ma (MSWD = 0.59), and thus belongs to the TIB1 (1.81–1.76 Ga) episode of the Transscandinavian Igneous Belt (TIB). Rare zircon xenocrysts extracted from the nepheline syenite show ages corresponding to 1.5 Ga lower crustal intrusives (rapakivi?), TIB, Svecofennian, and one Archaean zircon, which suggests the possibility for a remnant of Archaean basement below the TIB. There has historically been a vivid discussion about wheth- er or not Norra Kärr has been deformed and metamorphosed. New Ar-Ar step heating ages on sodic amphibole from Norra Kärr and muscovite and biotite from the country rocks give plateau ages at 1.1 Ga and 0.94 Ga, which correspond to ages derived for Sveconorwegian shear zones in the area. Together with textural and crystal chemical evidence, these ages make a compelling argument for some form of Sveconorwegian overprint of the Norra Kärr alkaline complex.
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| 13. |
- Sjöqvist, Axel S.L. 1990, et al.
(author)
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Magmatic age of rare-earth element and zirconium mineralisation at the Norra Kärr alkaline complex, southern Sweden, determined by U–Pb and Lu–Hf isotope analyses of metasomatic zircon and eudialyte.
- 2017
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In: Lithos. - : Elsevier BV. - 0024-4937. ; 294–295, s. 73-86
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Journal article (peer-reviewed)abstract
- The agpaitic Norra Kärr alkaline complex in southern Sweden is rich in heavy rare-earth elements and zirconium. Despite generally hosting high concentrations of Zr, agpaitic rocks sensu stricto are devoid of igneous zircon. During the late stages of magmatic intrusion, metasomatic Na- and F-rich fluids transporting Zr complexes caused fenitisation (syn-magmatic alkali metasomatism) of the granitic wall rocks, which formed new metasomatic zircon. Fenite zircon was dated by LA-MC-ICP-MS with the U–Pb method at 1.49 ± 0.01 Ga. The unaltered country rock granite was dated at 1.79 ± 0.01 Ga. Zircon in the fenites exhibits εHf +6.58 ± 0.36 at 1.49 Ga; significantly above the expected value for Svecofennian crust at that time (ca. –5 ± 2), but identical, within error, of that measured in eudialyte from Norra Kärr. This suggests a common source of Hf for fenite zircon and eudialyte from Norra Kärr, which isotopically strengthens the link between fenite and nepheline syenite. The 1.49 Ga age dates not only the fenitisation, but also the agpaitic intrusion, which caused the fenitisation, and with it the origin of the rare-earth element and Zr ore within the agpaites, which probably formed from an evolved magma derived from the mantle. A few zircon xenocrysts, which survived in the agpaitic magma, may indicate the presence of an Archaean component in the basement.
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| 15. |
- Sjöqvist, Axel S.L. 1990, et al.
(author)
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Three Compositional Varieties of Rare-Earth Element Ore: Eudialyte-Group Minerals from the Norra Kärr Alkaline Complex, Southern Sweden
- 2013
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In: Minerals. - : MDPI AG. - 2075-163X. ; 3:1, s. 94-120
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Journal article (peer-reviewed)abstract
- Agpaitic nepheline syenites at the Norra Kärr Alkaline Complex, southern Sweden, are rich in zirconium and rare-earth elements (REE), which are mainly accommodated in eudialyte-group minerals (EGM). Norra Kärr hosts three compositionally distinct groups of EGM, which are complex zirconosilicates. Analyses of EGM by electron beam energy-dispersive (SEM-EDS) and wavelength-dispersive (WDS-EMP) X-ray microanalysis are presented and compared, complemented by whole-rock analyses. The SEM-EDS and WDS-EMP methods produce comparable results for most elements. Considering that most SEM instruments have a user-friendly EDS system, it is a useful tool for reconnaissance work in research and especially in exploration-related studies. The EGM evolved markedly from an initial Fe-rich and REE-poor, but HREE-dominated variety, to an intermediate Fe-Mn and HREE-rich one, and to a final Mn- and LREE-rich variety, which occur in rocks classified as lakarpite and grennaite. Based on the Mn/(Fe+Mn) ratios of the EGM, this trend is interpreted as a result of magmatic evolution. The threefold diversity of EGM presented in this work is much broader than has previously been documented.
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| 16. |
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| 17. |
- Tong, D.M., et al.
(author)
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Kinematic approach to mixed state geometric phase in nonunitary evolution
- 2004
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 93:8, s. 080405-
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Journal article (peer-reviewed)abstract
- A kinematic approach to the geometric phase for mixed quantal states in nonunitary evolution is proposed. This phase is manifestly gauge invariant and can be experimentally tested in interferometry. It leads to well-known results when the evolution is unitary.
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| 18. |
- Tong, D.M., et al.
(author)
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Kinematic approach to off-diagonal geometric phases of nondegenerate and degenerate mixed states
- 2005
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In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 71:3, s. 032106-
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Journal article (peer-reviewed)abstract
- Off-diagonal geometric phases have been developed in order to provide information of the geometry of paths that connect noninterfering quantal states. We propose a kinematic approach to off-diagonal geometric phases for pure and mixed states. We further extend the mixed state concept proposed in [Phys. Rev. Lett. 90, 050403 (2003)] to degenerate density operators. The first and second order off-diagonal geometric phases are analyzed for unitarily evolving pairs of pseudopure states.
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| 19. |
- Tong, D.M., et al.
(author)
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Relation between geometric phases of entangled bi-partitesystems and their subsystems
- 2003
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In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 68, s. 022106-
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Journal article (peer-reviewed)abstract
- This paper focuses on the geometric phase of entangled states of bi-partite systems under bi-local unitary evolution. We investigate the relation between the geometric phase of the system and those of the subsystems. It is shown that (1) the geometric phase of cyclic entangled states with non-degenerate eigenvalues can always be decomposed into a sum of weighted non-modular pure state phases pertaining to the separable components of the Schmidt decomposition, though the same cannot be said in the non-cyclic case, and (2) the geometric phase of the mixed state of one subsystem is generally different from that of the entangled state even by keeping the other subsystem fixed, but the two phases are the same when the evolution operator satisfies conditions where each component in the Schmidt decomposition is parallel transported.
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| 20. |
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| 21. |
- Wampach, L., et al.
(author)
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Birth mode is associated with earliest strain-conferred gut microbiome functions and immunostimulatory potential
- 2018
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In: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 9:1
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Journal article (peer-reviewed)abstract
- The rate of caesarean section delivery (CSD) is increasing worldwide. It remains unclear whether disruption of mother-to-neonate transmission of microbiota through CSD occurs and whether it affects human physiology. Here we perform metagenomic analysis of earliest gut microbial community structures and functions. We identify differences in encoded functions between microbiomes of vaginally delivered (VD) and CSD neonates. Several functional pathways are over-represented in VD neonates, including lipopolysaccharide (LPS) biosynthesis. We link these enriched functions to individual-specific strains, which are transmitted from mothers to neonates in case of VD. The stimulation of primary human immune cells with LPS isolated from early stool samples of VD neonates results in higher levels of tumour necrosis factor (TNF-α) and interleukin 18 (IL-18). Accordingly, the observed levels of TNF-α and IL-18 in neonatal blood plasma are higher after VD. Taken together, our results support that CSD disrupts mother-to-neonate transmission of specific microbial strains, linked functional repertoires and immune-stimulatory potential during a critical window for neonatal immune system priming.
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| 22. |
- Wiren, K, et al.
(author)
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Enhancement of bioavailability by lowering of fat content in topical formulations
- 2009
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In: British Journal of Dermatology. - : Oxford University Press (OUP). - 0007-0963 .- 1365-2133. ; 160:3, s. 552-556
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Journal article (peer-reviewed)abstract
- The cosmetic properties of topical formulations are important parameters for the adherence to treatment, where modern oil-in-water emulsions are considered more acceptable compared with ointments. After application of an emulsion to the skin, the concentration of active ingredients in the formulation residue on the skin will increase, due to evaporation of volatile ingredients. The aim of the present study was to investigate the effect of changes in vehicle fatty content on the skin penetration of two active ingredients: benzyl nicotinate (BN) and betamethasone valerate (BV). Formulations containing 0.5% BN and 0.3% BV in vehicles with different lipid content (10-80%) were applied in a randomized and double-blind manner to the forearm of healthy volunteers. The changes in skin colour (erythema and blanching) were then monitored visually and with a new noninvasive instrument. The BN formulation containing 10% fat induced erythema more rapidly and with higher intensity than the formulations with higher fat content. Increased efficacy was also observed from the low-fat content formulation of BV, which gave more blanching than the formulations with high fat content. The rate of penetration of the active ingredients was inversely related to the lipid content, i.e. simple changes of the cosmetic properties by modifications of the lipid content may affect the efficacy of a formulation.
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| 23. |
- Xu, Guofu, et al.
(author)
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Composite nonadiabatic holonomic quantum computation
- 2017
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In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 95
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Journal article (peer-reviewed)abstract
- Nonadiabatic holonomic quantum computation has a robust feature in suppressing control errors because of its holonomic feature. However, this kind of robust feature is challenged since the usual way of realizing nonadiabatic holonomic gates introduces errors due to systematic errors in the control parameters. To resolve this problem, we here propose a composite scheme to realize nonadiabatic holonomic gates. Our scheme can suppress systematic errors while preserving holonomic robustness. It is particularly useful when the evolution period is shorter than the coherence time. We further show that our composite scheme can be protected by decoherence-free subspaces. In this case, the strengthened robust feature of our composite gates and the coherence stabilization virtue of decoherence-free subspaces are combined.
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| 24. |
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