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Sökning: WFRF:(Klason T)

  • Resultat 1-10 av 28
  • [1]23Nästa
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  • Berglin, Cecilia Engmér, et al. (författare)
  • Magnetic Resonance Imaging of the Middle and Inner Ear After Intratympanic Injection of a Gadolinium-Containing Gel
  • 2014
  • Ingår i: Otology and Neurotology. - 1531-7129 .- 1537-4505. ; 35:3, s. 526-532
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE:To investigate the distribution and elimination of a gadolinium containing high viscosity formulation of sodium hyaluronan (HYA gel) after injection to the middle ear.MATERIALS AND METHODS:The T1 contrast agent gadolinium-diethylenetriamine pentaacetic acid-bis methylamine (Gd-DTPA-BMA) was added to HYA gel and delivered to the middle ear of 13 albino guinea pigs by 3 different ways of injection. Magnetic resonance imaging was performed with a 4.7 T MRI system using a T1-weighted 3-dimentional rapid acquisition with relaxation enhancement sequence.RESULTS:An injection technique where the Gd-DTPA-BMA-containing HYA gel was delivered to the middle ear through a percutaneous injection through the auditory bulla after a small incision had been made in the tympanic membrane gave the best filling of the middle ear, covering the cochlea and the region of the round window niche for 24 hours in a majority of the ears studied. Ears injected without an incision in the tympanic membrane showed an immediate uptake of Gd-DTPA-BMA in the inner ear as a sign of rupture of the round window membrane.CONCLUSION:A percutaneous injection of a HYA gel into the tympanic bulla is distributed in a predictable way and gives a good filling of the middle ear cavity. The HYA gel remains in close vicinity to the RWM for more than 24 hours. Injection should be performed after an incision of the tympanic membrane has been made to prevent rupture of the round window membrane.
  • Børseth, T. Moe, et al. (författare)
  • Identification of oxygen and zinc vacancy optical signals in ZnO
  • 2006
  • Ingår i: Appl. Phys. Lett.. - 0003-6951 .- 1077-3118. ; 89
  • Tidskriftsartikel (refereegranskat)abstract
    • Photoluminescence spectroscopy has been used to study single crystalline ZnO samples systematically annealed in inert, Zn-rich and O-rich atmospheres. A striking correlation is observed between the choice of annealing ambient and the position of the deep band emission (DBE) often detected in ZnO. In particular, annealing in O2 results in a DBE at 2.35±0.05 eV, whereas annealing in the presence of metallic Zn results in DBE at 2.53±0.05 eV. The authors attribute the former band to zinc vacancy (VZn) related defects and the latter to oxygen vacancy (VO) related defects. Additional confirmation for the VO and VZn peak identification comes from the observation that the effect is reversible when O- and Zn-rich annealing conditions are switched. After annealing in the presence of ZnO powder, there is no indication for the VZn- or VO-related bands, but the authors observe a low intensity yellow luminescence band peaking at 2.17 eV, probably related to Li, a common impurity in hydrothermally grown ZnO.
  • Kim, D. K., et al. (författare)
  • Characterization and MRI study of surfactant-coated superparamagnetic nanoparticles administered into the rat brain
  • 2001
  • Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 225:02-jan, s. 256-261
  • Tidskriftsartikel (refereegranskat)abstract
    • A pre-clinical study has been carried out for the utilization of magnetite (Fe-3 O-4) nanoparticles as a diagnostic tracer for MRI. Surfactant-coated Fe3O4 nanoparticles have been synthesized by a chemical coprecipitation method with a narrow particle size of around 6 nm. Preliminary experiments demonstrated the feasibility of using superparamagnetic Fe-3 O-4 nanoparticles as contrast agents in MR imaging.
  • Counter, S Allen, et al. (författare)
  • MRI evidence of endolymphatic impermeability to the gadolinium molecule in the in vivo mouse inner ear at 9.4 tesla
  • 2013
  • Ingår i: The Open Neuroimaging Journal. - 1874-4400 .- 1874-4400. ; 7, s. 27-31
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE:Previous in vivo experimental magnetic resonance imaging (MRI) investigations of the mammalian inner ear at 4.7 Tesla have indicated that intravenously injected gadolinium (Gd) penetrates the perilymphatic labyrinth, but not the endolymphatic membranous labyrinth. In the present study, high field MRI at 9.4T was used to visualize the in vivo mouse vestibulo-cochlea system, and to determine whether the endolymphatic system is permeable to a Gd complex.METHODS:A 9.4 T Varian magnet equipped with a 12 cm inner diameter gradient system with maximum gradient strength of 600 mT/m, a millipede coil (Varian design) and a Gd contrast agent were used for image acquisition in the normal C57 BL-6 mouse.RESULTS:High-resolution 2D and 3D images of the mouse cochlea were acquired within 80 minutes following intravenous injection of Gd. Gd initially permeated the perilymphatic scala tympani and scala vestibuli, and permitted visualization of both cochlear turns from base to apex. The superior, inferior and lateral semicircular canals were subsequently visualized in 3 planes. The membranous endolymphatic labyrinth was impermeable to intravenously injected Gd, and thus showed no apparent uptake of Gd at 9.4T.CONCLUSION:The 9.4T field strength MRI permitted acquisition of high resolution images of anatomical and physiological features of the normal, wild type mouse perilymphatic inner ear in vivo, and provided further evidence that the endolymphatic system is impermeable to intravenously injected Gd.
  • da Silva, A. Ferreira, et al. (författare)
  • Growth, Electrical and Optical Properties of SnO2:F on ZnO, Si and Porous Si Structures
  • 2009
  • Konferensbidrag (refereegranskat)abstract
    • In this work we have analyzed the optical absorption of the ZnO and SnO2:F (FTO) films and applied them in porous silicon light-emitting diodes. The absorption and energy gap were calculated by employing the projector augmented wave method [1] within the local density approximation and with a modeled on-site self-interaction-like correction potential within the LDA+U-S/C [2]. Experiment and theory show a good agreement when the optical absorption and optical energy gap are considered. A layer of FTO is deposited by spray pyrolysis on top of porous Si (PSi) or ZnO/(PSi) in order to make the LEDs. The morphology and roughness of the films are analyzed by Atomic Force Microscopy before and after the FTO deposition. The electrical and optical properties are studied by characteristics curves J x V, and electroluminescence intensity versus bias.
  • Duan, Maoli, et al. (författare)
  • Imaging of the guinea pig cochlea following round window gadolinium application
  • 2004
  • Ingår i: NeuroReport. - : Wolters Kluwer. - 0959-4965 .- 1473-558X. ; 15:12, s. 1927-1930
  • Tidskriftsartikel (refereegranskat)abstract
    • Precise, non-invasive determination of the aetiology and site of pathology of inner ear disorders is difficult. The aim of this study was to describe an alternative method for inner ear visualization, based on local application of the paramagnetic contrast agent gadolinium. Using a 4.7 T MRI scanner, high contrast images of all four cochlear turns were obtained 3.5 h after placing gadolinium on the round window membrane. Gadolinium cleared from the cochlea within 96 h. Auditory brainstem response measurements performed on a separate group of animals showed no significant threshold shifts after the application, indicating that gadolinium is non-toxic to the guinea pig cochlea.
  • Merlone, A., et al. (författare)
  • The MeteoMet project - metrology for meteorology: challenges and results
  • 2015
  • Ingår i: Meteorological Applications. - 1350-4827 .- 1469-8080. ; 22, s. 820-829
  • Tidskriftsartikel (refereegranskat)abstract
    • The study describes significant outcomes of the Metrology for Meteorology' project, MeteoMet, which is an attempt to bridge the meteorological and metrological communities. The concept of traceability, an idea used in both fields but with a subtle difference in meaning, is at the heart of the project. For meteorology, a traceable measurement is the one that can be traced back to a particular instrument, time and location. From a metrological perspective, traceability further implies that the measurement can be traced back to a primary realization of the quantity being measured in terms of the base units of the International System of Units, the SI. These two perspectives reflect long-standing differences in culture and practice and this project - and this study - represents only the first step towards better communication between the two communities. The 3 year MeteoMet project was funded by the European Metrology Research Program (EMRP) and involved 18 European National Metrological Institutes, 3 universities and 35 collaborating stakeholders including national meteorology organizations, research institutes, universities, associations and instrument companies. The project brought a metrological perspective to several long-standing measurement problems in meteorology and climatology, varying from conventional ground-based measurements to those made in the upper atmosphere. It included development and testing of novel instrumentation as well as improved calibration procedures and facilities, instrument intercomparison under realistic conditions and best practice dissemination. Additionally, the validation of historical temperature data series with respect to measurement uncertainties and a methodology for recalculation of the values were included.
  • Oberg, Johanna, et al. (författare)
  • Age related changes in brain metabolites observed by 1H MRS in APP/PS1 mice
  • 2008
  • Ingår i: Neurobiology of Aging. - 0197-4580 .- 1558-1497. ; 29:9, s. 1423-1433
  • Tidskriftsartikel (refereegranskat)abstract
    • Translational biomarkers in Alzheimer's disease based on non-invasive in vivo methods are highly warranted. (1)H magnetic resonance spectroscopy (MRS) is non-invasive and applicable in vivo in both humans and experimental animals. In vivo(1)H MRS and 3D MRI were performed on brains of double transgenic (tg) mice expressing a double mutant human beta-amyloid precursor protein APP(K670N,M671L) and human mutated presenilin gene PS1M146L, and wild-type (wt) littermates at 2.5, 6.5 and 9 months of age using a 9.4T magnet. For quantification, LCModel was used, and the data were analyzed using multivariate data analysis (MVDA). MVDA evidenced a significant separation, which became more pronounced with age, between tg and wt mice at all time points. While myo-inositol and guanidoacetate were important for group separation in young mice, N-acetylaspartate, glutamate and macrolipids were important for separation of aged tg and wt mice. Volume segmentation revealed that brain and hippocampus were readily smaller in tg as compared to wt mice at the age of 2.5 months. Amyloid plaques were seen in 6.5 and 9 months, but not in 2.5 months old animals. In conclusion, differences in brain metabolites could be accurately depicted in tg and wt mice in vivo by combining MRS with MVDA. First differences in metabolite content were readily seen at 2.5 months, when volume defects in tg mice were present, but no amyloid plaques.
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  • Resultat 1-10 av 28
  • [1]23Nästa

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