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- Wagner-Drouet, E, et al.
(författare)
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Standardized monitoring of cytomegalovirus-specific immunity can improve risk stratification of recurrent cytomegalovirus reactivation after hematopoietic stem cell transplantation
- 2021
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 1592-8721 .- 0390-6078. ; 106:2, s. 363-374
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Tidskriftsartikel (refereegranskat)abstract
- Recurrence of cytomegalovirus reactivation remains a major cause of morbidity and mortality following allogeneic hematopoietic stem cell transplantation. Monitoring cytomegalovirus-specific cellular immunity using a standardized assay might improve the risk stratification of patients. A prospective multicenter study was conducted in 175 intermediate- and high-risk allogeneic hematopoietic stem cell transplant recipients under preemptive antiviral therapy. Cytomegalovirus-specific cellular immunity was measured using a standardized IFN-γ ELISpot assay (T-Track® CMV). Primary aim was to evaluate the suitability of measuring cytomegalovirus-specific immunity after end of treatment for a first cytomegalovirus reactivation to predict recurrent reactivation. 40/101 (39.6%) patients with a first cytomegalovirus reactivation experienced recurrent reactivations, mainly in the high-risk group (cytomegalovirus-seronegative donor/cytomegalovirus-seropositive recipient). The positive predictive value of T-Track® CMV (patients with a negative test after the first reactivation experienced at least one recurrent reactivation) was 84.2% in high-risk patients. Kaplan-Meier analysis revealed a higher probability of recurrent cytomegalovirus reactivation in high-risk patients with a negative test after the first reactivation (hazard ratio 2.73; p=0.007). Interestingly, a post-hoc analysis considering T-Track® CMV measurements at day 100 post-transplantation, a time point highly relevant for outpatient care, showed a positive predictive value of 90.0% in high-risk patients. Our results indicate that standardized cytomegalovirus-specific cellular immunity monitoring may allow improved risk stratification and management of recurrent cytomegalovirus reactivation after hematopoietic stem cell transplantation. This study was registered at www.clinicaltrials.gov as #NCT02156479.
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- Pingen, Katrin, et al.
(författare)
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High growth rate magnetron sputter epitaxy of GaN using a solid Ga target
- 2024
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Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 220
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Tidskriftsartikel (refereegranskat)abstract
- Magnetron sputter epitaxy (MSE) is a promising processing route for group-III nitride semiconductors, with the potential to enable high-quality and low cost GaN growth for widespread use. However, fundamental techno-logical hurdles must be overcome to enable the adoption of MSE in industrial production. Here, we present a new UHV-compatible magnetron design with high-performance cooling, enabling high GaN growth rates at high growth temperatures using a solid Ga target. The magnetron is tested with a wide range of process parameters and a stable process is feasible while maintaining the solid state of the Ga target. High GaN growth rates of up to 5 mu m/h are achieved at room temperature and a growth rate of 4 mu m/h at high temperature, which is one order of magnitude higher compared to MSE with a liquid target. We grow GaN on c-plane sapphire substrates and show the impact of partial pressure ratio and target-to-substrate distance (TSD) on growth rate, film morphology and crystal quality of GaN films with scanning electron microscopy and X-ray diffraction. While the growth rate and film morphology are strongly impacted by the process parameter variation, the crystal quality is further impacted by the overall film thickness. For a 2 mu m thick GaN film a full width at half maximum of X-ray rocking curve (omega-FWHM) of GaN 10 1 1 reflection of 0.32 degrees is achieved. We demonstrate a process window for growth of dense and smooth GaN films with high crystal quality using low N2 flow rates and high TSD. By introducing a 20 nm AlN nucleation layer prior to the growth of 390 nm GaN, the omega-FWHM of GaN 0002 reflection of 0.19 degrees is achieved. The epitaxially grown crystalline structure is precisely examined by transmission electron microscopy.
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