| 1. |
- Feroci, M., et al.
(författare)
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The large observatory for x-ray timing
- 2014
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 9780819496126
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Konferensbidrag (refereegranskat)abstract
- The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final downselection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supranuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m2 effective area, 2-30 keV, 240 eV spectral resolution, 1° collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g. GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the status of the mission at the end of its Phase A study.
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| 2. |
- Feroci, M., et al.
(författare)
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The Large Observatory for X-ray Timing (LOFT)
- 2012
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Ingår i: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 34:2, s. 415-444
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Tidskriftsartikel (refereegranskat)abstract
- High-time-resolution X-ray observations of compact objects provide direct access to strong-field gravity, to the equation of state of ultradense matter and to black hole masses and spins. A 10 m(2)-class instrument in combination with good spectral resolution is required to exploit the relevant diagnostics and answer two of the fundamental questions of the European Space Agency (ESA) Cosmic Vision Theme "Matter under extreme conditions", namely: does matter orbiting close to the event horizon follow the predictions of general relativity? What is the equation of state of matter in neutron stars? The Large Observatory For X-ray Timing (LOFT), selected by ESA as one of the four Cosmic Vision M3 candidate missions to undergo an assessment phase, will revolutionise the study of collapsed objects in our galaxy and of the brightest supermassive black holes in active galactic nuclei. Thanks to an innovative design and the development of large-area monolithic silicon drift detectors, the Large Area Detector (LAD) on board LOFT will achieve an effective area of similar to 12 m(2) (more than an order of magnitude larger than any spaceborne predecessor) in the 2-30 keV range (up to 50 keV in expanded mode), yet still fits a conventional platform and small/medium-class launcher. With this large area and a spectral resolution of < 260 eV, LOFT will yield unprecedented information on strongly curved spacetimes and matter under extreme conditions of pressure and magnetic field strength.
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| 3. |
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| 4. |
- Altincekic, T. G., et al.
(författare)
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Synthesis and characterization of CuFe2O4 nanorods synthesized by polyol route
- 2010
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 493:1-2, s. 493-498
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Tidskriftsartikel (refereegranskat)abstract
- Uniform, high quality, CuFe2O4 nanorods with high aspect ratios were synthesized by a surfactant-free single step polyol process at 220 degrees C. The structure of the product was characterized by XRD and FT-IR, and the morphology of the product was analyzed by SEM. The results showed that the as-prepared nanorods have a uniform cross-section and with average diameter of similar to 100 nm and aspect ratio in the range of 13-52. X-ray line profile fitting resulted in crystallite size of 15 nm, which reveals the polycrystalline nature of these nanorods. Magnetic characterization of product was performed by EPR and VSM techniques and the results show that the CuFe2O4 nanorods are ferromagnetic. The line width of the resonance lines in FMR is about 1.8 kOe which may originate from different resonance fields of randomly distributed nanocrystals which have different orientation of magnetic easy axes.
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| 5. |
- Cai, Y., et al.
(författare)
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Propagation of laser array beams in a turbulent atmosphere
- 2007
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Ingår i: Applied physics. B, Lasers and optics (Print). - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 88:3, s. 467-475
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Tidskriftsartikel (refereegranskat)abstract
- The propagation of phase-locked and non-phase-locked laser array beams of radial and rectangular symmetries in a turbulent atmosphere are investigated based on the extended Huygens-Fresnel integral. The beamlet used in our paper for constructing the laser array beams is of elliptical Gaussian mode. Analytical formulae for the average irradiance of phase-locked and non-phase-locked radial and rectangular laser array beams are derived through vector integration and tensor operation. The irradiance properties of these laser array beams in a turbulent atmosphere are studied numerically. It is found that both phase-locked and non-phase-locked radial and rectangular laser array beams eventually become circular Gaussian beams in a turbulent atmosphere, which is much different from their propagation properties in free space. The propagation properties are closely related to the parameters of laser array beams and the structure constant of the turbulent atmosphere.
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| 6. |
- Durmus, Z., et al.
(författare)
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The effect of neutralizing agent on the synthesis and characterization of Mn3O4 nanoparticles
- 2010
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Ingår i: Russian Journal of Inorganic Chemistry. - 0036-0236 .- 1531-8613. ; 55:12, s. 1947-1952
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Tidskriftsartikel (refereegranskat)abstract
- We report on the synthesis of Mn3O4 nanoparticles via a two-step hydrothermal route by using Mn(CH3COO)(2) as the only starting material and TMAOH and NaOH as hydrolysing agents. XRD and FT-IR analyses confirmed the composition and structure of Mn3O4. TEM images showed that spheroid Mn3O4 nanostructures obtained by this method have average particle size of 6 and 14 nm for NaOH and TMAOH hydrolyzed samples respectively. Particle size analysis indicated a strong aggregation of nanoparticles and exhibited bi-modal distribution with average size of aggregates as similar to 250 nm and 1.1 mu m for both samples. Zeta potential analysis revealed adsorbed TMAOH species on the surface of Mn3O4 nanoparticles hydrolyzed using TMAOH. ESR analyses resulted in broader lines and smaller g values than bulk Mn3O4 nanoparticles, probably due to the exchange-coupled system with unlike spins such as canted spin at surface of high-surface-disordered nanoparticles.
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| 7. |
- Kaya, Ibrahim, et al.
(författare)
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Brain region-specific amyloid plaque-associated myelin lipid loss, APOE deposition and disruption of the myelin sheath in familial Alzheimer's disease mice
- 2020
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Ingår i: Journal of Neurochemistry. - : Wiley. - 0022-3042 .- 1471-4159. ; 154:1, s. 84-98
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Tidskriftsartikel (refereegranskat)abstract
- There is emerging evidence that amyloid beta (A beta) aggregates forming neuritic plaques lead to impairment of the lipid-rich myelin sheath and glia. In this study, we examined focal myelin lipid alterations and the disruption of the myelin sheath associated with amyloid plaques in a widely used familial Alzheimer's disease (AD) mouse model; 5xFAD. This AD mouse model has A beta(42) peptide-rich plaque deposition in the brain parenchyma. Matrix-assisted laser desorption/ionization imaging mass spectrometry of coronal brain tissue sections revealed focal A beta plaque-associated depletion of multiple myelin-associated lipid species including sulfatides, galactosylceramides, and specific plasmalogen phopshatidylethanolamines in the hippocampus, cortex, and on the edges of corpus callosum. Certain phosphatidylcholines abundant in myelin were also depleted in amyloid plaques on the edges of corpus callosum. Further, lysophosphatidylethanolamines and lysophosphatidylcholines, implicated in neuroinflammation, were found to accumulate in amyloid plaques. Double staining of the consecutive sections with fluoromyelin and amyloid-specific antibody revealed amyloid plaque-associated myelin sheath disruption on the edges of the corpus callosum which is specifically correlated with plaque-associated myelin lipid loss only in this region. Further, apolipoprotein E, which is implicated in depletion of sulfatides in AD brain, is deposited in all the A beta plaques which suggest apolipoprotein E might mediate sulfatide depletion as a consequence of an immune response to A beta deposition. This high-spatial resolution matrix-assisted laser desorption/ionization imaging mass spectrometry study in combination with (immuno) fluorescence staining of 5xFAD mouse brain provides new understanding of morphological, molecular and immune signatures of A beta plaque pathology-associated myelin lipid loss and myelin degeneration in a brain region-specific manner.
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| 8. |
- Ozkaya, T., et al.
(författare)
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A novel synthetic route to Mn3O4 nanoparticles and their magnetic evaluation
- 2008
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 403:19-20, s. 3760-3764
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Tidskriftsartikel (refereegranskat)abstract
- Manganese oxide (Mn3O4) nanoparticles were successfully prepared by a novel oxidation-precipitation method based on oxidation of manganese sulfate to manganese salts and hydrolyzing with NaOH and concentrated NH3. X-ray diffraction (XRD) analysis confirmed the tetragonal haussmanite structure with average crystallite size of similar to 14 and similar to 11 nm: transmission electron microscopy (TEM) analysis showed crystallite size of 14 5 and 12 3 nm for NaOH- and NH3-hydrolyzed samples, respectively. The ferromagnetic transition temperatures are 38 and 40 K for NaOH- and NH3-hydrolyzed samples, respectively. These values are lower than that of bulk Mn3O4. Both samples show superparamagnetic behavior at room temperature, with no apparent saturation magnetization and hysteresis in the region of measured field strength, and they also exhibit relatively large coercivity below the ferromagnetic transition temperature. Below the transition, marked differences are observed in temperature dependence of magnetization, hysteresis loop shape, and type of the samples from the bulk values. The particles are considered as single magnetic domains with random orientations of magnetic moments and thermal fluctuations of anisotropic axes. These results are attributed to the smaller size (increase in surface to volume ratio) of the samples, which cause an increase of effective magnetic surface anisotropy.
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| 9. |
- Ozkaya, T., et al.
(författare)
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Reflux synthesis of Co3O4 nanoparticles and its magnetic characterization
- 2009
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 321:14, s. 2145-2149
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Tidskriftsartikel (refereegranskat)abstract
- Co3O4 nanoparticles have been prepared for the first time via reflux method, as an alternative low-temperature high-yield process, starting from one single precursor. A plausible mechanism is suggested for the synthetic process. XRD, TEM, FTIR and VSM were used for the structural, morphological, spectroscopic, and magnetic characterization of the product respectively. X-ray diffraction line profile fitting showed that average particle size of the sample is 28 nm. Morphology of the synthesized powder was observed to be thin nanosheets with a thickness of 2-3 nm based on SEM and TEM analyses. Magnetic measurements showed a deviation of the Neel temperature from the bulk value which is attributed to the finite size effects. A loop shift with an enhanced coercivity is observed in the field-cooled hysteresis loops. The opening of the hysteresis loop reveals the existence of the spin-glass like surface spins of the Co3O4 nanoparticles.
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| 10. |
- Watts, Anna L., et al.
(författare)
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Dense matter with eXTP
- 2019
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Ingår i: Science China Physics, Mechanics & Astronomy. - : Science Press. - 1674-7348 .- 1869-1927. ; 62:2
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Forskningsöversikt (refereegranskat)abstract
- In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry (eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is expected to be launched in the mid 2020s.
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