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- Gu, Y. W., et al.
(författare)
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Solid state synthesis of nanocrystalline and/or amorphous 50Ni-50Ti alloy
- 2005
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936. ; 392:1-2, s. 222-228
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Tidskriftsartikel (refereegranskat)abstract
- A nanocrystalline/amorphous 50Ni-50Ti alloy was produced by solid state synthesis via mechanical alloying from elemental Ti and Ni powders. Using X-ray diffraction analysis and transmission electron microscopy techniques, a mechanically induced solid state reaction of 50Ni-50Ti was investigated. Results showed that nanocrystalline and amorphous Ni-Ti phases were obtained after mechanical alloying. The mechanical alloying of 50Ni-50Ti for 270 ks led to the formation of f.c.c. Ni(Ti) solid solution, characterized by a lattice parameter of 0.3558 nm, crystallite size of 14 nm and lattice strain of 0.98%. The particle size decreased with increasing milling time. The crystallite size of mechanically alloyed 50Ni-50Ti powders was substantially refined as the milling proceeded and the lattice strain increased with the milling time. The steady-state crystallite size was approximately 10-15 nm. The internal lattice strain in Ni-Ti alloy led to the disordering and the subsequent formation of amorphous alloy during mechanical alloying. After heat treatment at 1100 °C, the as-milled powders transformed into B2-NiTi phase and a small amount of Ti2Ni phase. © 2004 Elsevier B.V. All rights reserved.
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- Bergroth, T., et al.
(författare)
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Selection of drug-resistant HIV-1 during the early phase of viral decay is uncommon in treatment-naive patients initiated on a three- or four-drug antiretroviral regimen including lamivudine
- 2009
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Ingår i: Journal of medical virology. - : Wiley. - 1096-9071 .- 0146-6615. ; 81:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Therapy failure due to drug resistance development is a common phenomenon in HIV-infected patients. However, when the drug pressure leads to the earliest selection of drug-resistant HIV-1 populations is still unclear. In this study, the extent to which selection of the HIV-1 reverse transcriptase M184I/V mutations occur during the initial phase of viral decay in treatment-naive HIV-1 infected patients receiving antiretroviral therapy (ART) was examined. Plasma virus from three cohorts of treatment-naive patients initiating quadruple (n = 43), triple (n = 14) or dual (n = 15) lamivudine-containing ART were analyzed for M184I/V during the first 6 months of therapy using direct sequencing and a sensitive selective real-time PCR method. Among quadruple ART patients, who all were treated at primary HIV-1 infection, only one patient developed M184V after 6 weeks of therapy, having had wild-type virus at baseline. No mutations were found in chronically infected patients on triple ART. In patients on dual therapy, M184I/V mutants were found frequently. Selection of M184I/V mutants was found to be rare during the initial phase of viral decay after initiation of ART in adherent patients given a three or four-drug combination, in contrast to those receiving a less potent regimen. The results suggest that triple and quadruple lamivudine + PI or PI/r containing ART given to treatment-naive adherent patients is potent enough to prevent development of resistance during the first months of therapy.
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