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Träfflista för sökning "WFRF:(Hansson Göran) ;lar1:(liu)"

Sökning: WFRF:(Hansson Göran) > Linköpings universitet

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1.
  • Engström, Gunnar, et al. (författare)
  • The Swedish CArdioPulmonary BioImage Study : objectives and design
  • 2015
  • Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 278:6, s. 645-659
  • Tidskriftsartikel (refereegranskat)abstract
    • Cardiopulmonary diseases are major causes of death worldwide, but currently recommended strategies for diagnosis and prevention may be outdated because of recent changes in risk factor patterns. The Swedish CArdioPulmonarybioImage Study (SCAPIS) combines the use of new imaging technologies, advances in large-scale 'omics' and epidemiological analyses to extensively characterize a Swedish cohort of 30 000 men and women aged between 50 and 64 years. The information obtained will be used to improve risk prediction of cardiopulmonary diseases and optimize the ability to study disease mechanisms. A comprehensive pilot study in 1111 individuals, which was completed in 2012, demonstrated the feasibility and financial and ethical consequences of SCAPIS. Recruitment to the national, multicentre study has recently started.
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2.
  • Gullestad, Lars, et al. (författare)
  • Long-term outcomes of thoracic transplant recipients following conversion to everolimus with reduced calcineurin inhibitor in a multicenter, open-label, randomized trial
  • 2016
  • Ingår i: Transplant International. - : Wiley-Blackwell Publishing Inc.. - 0934-0874 .- 1432-2277. ; 29:7, s. 819-829
  • Tidskriftsartikel (refereegranskat)abstract
    • The NOCTET study randomized 282 patients ≥1 year after heart or lung transplantation to continue conventional calcineurin inhibitor (CNI) therapy or to start everolimus with reduced-exposure CNI. Last follow-up, at ≥5 years postrandomization (mean: 5.6 years) was attended by 72/140 everolimus patients (51.4%) and 91/142 controls (64.1%). Mean measured GFR remained stable in the everolimus group from randomization (51.3 ml/min) to last visit (51.4 ml/min) but decreased in controls (from 50.5 ml/min to 45.3 ml/min) and was significantly higher with everolimus at last follow-up (P = 0.004). The least squares mean (SE) change from randomization was -1.5 (1.7)ml/min with everolimus versus -7.2 (1.7)ml/min for controls (difference: 5.7 [95% CI 1.7; 9.6]ml/min; P = 0.006). The difference was accounted for by heart transplant patients (difference: 6.9 [95% 2.3; 11.5]ml/min; P = 0.004). Lung transplant patients showed no between-group difference at last follow-up. Rates of rejection, death, and major cardiac events were similar between groups, as was graft function. Pneumonia was more frequent with everolimus (18.3% vs. 6.4%). In conclusion, introducing everolimus in maintenance heart transplant patients, with reduced CNI, achieves a significant improvement in renal function which is maintained for at least 5 years, but an early renal benefit in lung transplant patients was lost. Long-term immunosuppressive efficacy was maintained.
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3.
  • Adnane, Bouchaib (författare)
  • Optical characterization of Silicon-based self-assembled nanostructures
  • 2010
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This PhD thesis summarizes the work carried on the optical characterizations of some Si-based self-assembled nanostructures, particularly SiGe/Si quantum dots (QDs) and nanocrystalline (nc)-Si embedded in mesoporous silica (MS) using photoconductivity (PC), photoluminescence (PL), and photoluminescence excitation (PLE) measurements. The spectroscopic studies of SiGe/Si QDs grown on Si by molecular beam epitaxy revealed for the first time well-resolved PLE resonances. When correlated with numerical analysis, these resonances were directly related to the co-existence of spatially direct (inside the SiGe dot) and indirect (across the Si/Ge interface) recombination processes involving different dot populations selected by the monitored detection energy for PLE acquisition. The characteristics of these two transitions were further studied in detail by PLE (in some case implemented together with selective PL) on various samples, which contained either only one Ge dot layer or multiple Gedot/Si stacks, grown at substrate temperatures ranging from 430 to 580 °C; especially the temperature- and excitation power-dependence of the excitation properties. The results illustrated that the electronic structure of SiGe dots are influenced by size, Ge composition, as well as strain connected, and sometimes a mixed effect. Another attempt of the project was the fabrication of lateral transport mid-infrared photodetectors based on multiple Ge-dot/Si stacked structures. A broadband photoresponsivity of the processed multi-finger detectors was estimated to be about 90 mA/W over 3-15 μm range at 20 K, and the peaked photoresponse was measured at ~10 μm. The origin of the measured photocurrent, as elucidated by photoluminescence and photoluminescence excitation spectroscopies, was related to intersubband absorption of normal incidence infrared radiation corresponding to energies between the ground states of the heavy hole and the light hole in the valence band of the SiGe/Si QDs, and subsequent charge transfer to the Ge 2D wetting layer acting as a conduction channel. The absence of photocurrent in the energy range expected for a transition from the ground state to the first excited state of the heavy hole indicated that the holes in the SiGe dots behave essentially as 2D in character rather than a truly 3D confinement, where the transitions between heavy holes states are not allowed for TE polarized radiation (normal incidence). Finally, Si(or Ge) nanocrystals embedded in mesoporous silica samples prepared by spincoating and atomic layer chemical vapor deposition were optically investigated by means of PL with various excitation powers, together with several attempts using different post rapid thermal annealing processes. The shape and energy position of the PL spectra of the nc-Si embedded in MS samples and a reference MS template without nc incorporation were rather similar, but the luminescence was much more intense for those embedded with nanocrystals. This implies that the emission mechanism for MS samples with or without nc-Si could be the same, i.e., the light emission was governed by the surface properties of silica. The semiconductor nanocrystals played a role by sensitizing the luminescence emission through generating more photo-excited carriers. These carriers were then trapped in the defect state e.g. the interfacial oxygen defect sites and subsequently recombine to increase the PL intensity.
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4.
  • Adnane, Bouchaib, et al. (författare)
  • Origin of photoresponse at 8-14 μm in stacks of self-assembled SiGe/Si quantum dots
  • 2009
  • Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X.
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • A normal incidence photodetector operating at 8-14 μm is demonstrated using p-type δ-doped SiGe dot multilayer structures grown by molecular beam epitaxy on Si(001) substrates. Based on the experimental results of photoluminescence and photoluminescence excitation spectroscopies together with numerical analysis, the origin of the measured photocurrent was attributed to intersubband optical transitions between the heavy hole and light hole states of the valence band of the self-assembled SiGe dots and subsequent lateral transport of photo-excited carriers in the conduction channels formed by Ge wetting layers.
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5.
  • Adnane, Bouchaib, et al. (författare)
  • Photoluminescence excitation spectroscopy of self-assembled SiGe/Si quantum dots
  • 2009
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Photoluminescence excitation (PLE) experiments are reported for various self-assembled SiGe/Si dot samples grown on Si(001) by molecular beam epitaxy at substrate temperatures ranging from 430 to 580 C. Two excitation peaks were observed, and the characteristics of the involved optical transitions were studied in detail by PLE (in one case implemented together with selective photoluminescence, SPL) on different samples containing either only one SiGe dot layer or multiple SiGe-dot/Si stacks. The temperature- and power-dependence of the excitation properties together with the results of six-band k.p calculations support the assignment of the observed PLE peaks to spatially direct and indirect transitions collected from two different SiGe dot populations.
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6.
  • Adnane, Bouchaib, et al. (författare)
  • Spatially direct and indirect transitions of self-assembled SiGe/Si quantum dots studied by photoluminescence excitation spectroscopy
  • 2010
  • Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 96:18, s. 181107-
  • Tidskriftsartikel (refereegranskat)abstract
    • Well-resolved photoluminescence excitation (PLE) spectra are reported for selfassembled SiGe dots grown on Si(100) by molecular beam epitaxy. The observation of two excitation resonance peaks is attributed to two different excitation/de-excitation routes of interband optical transitions connected to the spatially direct and indirect recombination processes. It is concluded that two dot populations are addressed by each monitored luminescence energy for the PLE acquisition.
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7.
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8.
  • Du, Chun-Xia, et al. (författare)
  • Efficient 1.54 µm light emission from Si/SiGe/Si : Er
  • 2001
  • Ingår i: Materials Science & Engineering. - 0921-5107 .- 1873-4944. ; 81:1-3, s. 105-108
  • Tidskriftsartikel (refereegranskat)abstract
    • Si/SiGe/Si:Er:O-heterojunction bipolar transistor (HBT)-type light emitting devices with Er3+ ions incorporated in the collector region have been fabricated using layered structures prepared by differential molecular beam epitaxy (MBE). Intense light emission at 1.54 µm has been observed at room temperature by hot electron impact excitation at rather low injection current and applied voltage. Separate controls of the injection current and bias voltage make it possible to perform detailed electroluminescence (EL) studies that can not be done with conventional Si:Er light emitting diodes (LEDs). Saturation of the EL intensity occurs at very low current densities indicating a 100-fold increase of the effective excitation cross-section for Si/SiGe/Si:Er:O-HBTs compared with Si:Er-LEDs. © 2001 Elsevier Science B.V.
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9.
  • Du, Chun-Xia, et al. (författare)
  • Electroluminescence studies of Er and SiO co-doped Si layers prepared by molecular beam epitaxy
  • 2000
  • Ingår i: Optical materials (Amsterdam). - 0925-3467 .- 1873-1252. ; 14:3, s. 259-265
  • Tidskriftsartikel (refereegranskat)abstract
    • Er/O co-doped Si light emitting diodes (LEDs) have been fabricated using layer structures prepared by molecular beam epitaxy (MBE). The Er/O doping was realized by sublimation of elemental Er and silicon monoxide simultaneously with Si during MBE growth. Intense Er-related electroluminescence (EL) at 1.54 mu m was observed at room temperature from p(+)-SiGe/i-SiGe-Si/Si:Er/n(+)-Si LEDs by electron impact excitation under reverse bias. It has been found that the EL intensity was increased with increasing growth temperature of the Si:Er/O layer in the range of 430-575 degrees C. The electrical pumping power dependence of EL intensity has been studied. An excitation cross section value of similar to 1 x 10(-16) cm(2) was estimated based on the experimental data and model fitting. The EL decay behavior under various injection and bias conditions has been studied by time-resolved EL measurements. The overall luminescence decay time is found to strongly depend on the injection parameters. Two types of de-excitation mechanisms due to Auger energy transfer to free carriers introduced by either dopant ionization or carrier injection have been discussed. Both Auger processes play an important role in reduction of the EL intensity when there is a high density of carriers with excited Er ions. (C) 2000 Elsevier Science B.V. All rights reserved.
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10.
  • Du, Chun-Xia, et al. (författare)
  • Si/SiGe/Si : Er
  • 2001
  • Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 78:12, s. 1697-1699
  • Tidskriftsartikel (refereegranskat)abstract
    • Si/SiGe/Si:Er:O heterojunction bipolar transistor (HBT) type light-emitting devices with Er3+ ions incorporated in the collector region have been fabricated using a layered structure grown by differential molecular-beam epitaxy. Electroluminescence measurements on processed light-emitting HBTs can be performed in either constant driving current mode or constant applied bias mode, which is an important advantage over conventional Si:Er light-emitting diodes. Intense room-temperature light emission at the Er3+ characteristic wavelength of 1.54 µm has been observed at low driving current density, e.g., 0.1 A cm-2, and low applied bias, e.g., 3 V, across the collector and emitter. © 2001 American Institute of Physics.
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