| 1. |
- Dou, S.X., et al.
(författare)
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Microstructure and flux pinning in superconducting Bi-Pb-Sr-Ca-Cu-O wires
- 1990
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Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 172:1-2, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- The critical current density (Jc) of Ag-clad Bi-Pb-Sr-Ca-Cu-O wire has been measured to be 1.2×104 A/cm2 at 77 K in zero field. The high Jc is attributed to a combination of elimination of the poisoning effect of Ag on superconductivity, grain alignment, and enhancement of flux pinning. Jc-H dependence was significantly improved in the Ag-clad tape, which has a Jc of 1.0×103 A /cm2 at 77 K and 4000 Oe, while the Jc of the sintered pellet drops two orders of magnitude at only 100 Oe. A pronounced anisotropy in Jc under high magnetic field is attributed to the grain alignment. Planar defects, such as heavy stacking faults parallel to the a-b plane in the rolled tape, are considered to be effective pinning centres.
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| 2. |
- Imreh, S, et al.
(författare)
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Hypersomy of chromosome 15 with retrovirally rearranged c-myc, loss of germline c-myc and IgK/c-myc juxtaposition in a macrophage-monocytic tumour line
- 1994
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Ingår i: European Journal of Cancer. - 0959-8049. ; 30A:7, s. 994-1002
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Tidskriftsartikel (refereegranskat)abstract
- From a lymphoid tumour induced by 7,12-dimethylbenz-[a]-anthracene (DMBA) + methyl-N-nitrose-N-urea (MNU) in an [AKR Rb(6.15) x CBAT6T6]F1 mouse, a macrophage- monocyte line (KT-10) was isolated. Following ethyl methanesulfonate (EMS) treatment, a bromodeoxyuridine (BUdR) resistant subline was selected. Serial propagation of this line in vitro in the presence of BUdR (28 months) with periodic cytogenetic and molecular examinations, has led to the definition of four successive stages. During stage I, the cells were trisomic for chromosome 15. They contained Rb(6.15) and Rb(del6.15) of AKR and T(14;15) of CBA origin. Southern blotting showed the presence of both germline (G) and rearranged (R) c-myc. At stage II, Rb(del6.15) has duplicated. Both Rb(6.15) and T(14;15) persisted together with G-myc and R-myc. In stage III, the CBA-derived T(14;15) was lost, in parallel with G-myc. At this stage, a Dic.In(6.15) was detected. One of its arms was cytogenetically identical with the long arm of In(6.15) in the variant IgK/myc translocations. This chromosome carried R-myc and IgK in juxtaposition, as indicated by comigration on pulsed field electrophoresis (PFGE). At stage IV, the R-myc carrying AKR-derived chromosome 15s were present in six copies. Possible relationships between the increasing R/G myc ratio and changed growth characteristics in vivo and in vitro are discussed.
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| 3. |
- Axelson, H, et al.
(författare)
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Juxtaposition of N-myc and Ig kappa through a reciprocal t(6;12) translocation in a mouse plasmacytoma
- 1994
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Ingår i: Genes, Chromosomes and Cancer. - 1045-2257. ; 11:2, s. 85-90
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Tidskriftsartikel (refereegranskat)abstract
- Nearly all mouse plasmacytomas (MPCs) carry an Ig/myc translocation. Any one of the three Ig loci may participate, while the myc contribution has been limited to c-myc, excluding other members of the myc gene family. The same is true for the other two known Ig/myc translocation-carrying tumors, Burkitt's lymphoma and rat immunocytoma. It is believed that the Ig/myc juxtaposition plays a decisive, rate limiting role in the genesis of the three tumors, acting through the constitutive activation of myc that makes it refractory to normal regulation. Here we describe the molecular analysis of a unique t(6;12)(CI;B) translocation that we previously identified in an exceptional MPC that expressed N-myc but not c-myc. We now show that the translocation led to the juxtaposition of N-myc and Ig kappa. This is the first case of an Ig/myc-carrying tumor that involves N-myc rather than c-myc. These findings suggest that the translocation may already have occurred at the pro- or pre-B cell stage at which N-myc is open for transcription. According to this interpretation, constitutive activation of N-myc would suppress the expression of c-myc, but would not interfere with the differentiation of the pro-B cell into a fully mature plasma cell. Its tumorigenic influence would become manifest only at the time when the cell would normally be programmed to leave the cycling compartment, in connection with its terminal differentiation.
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| 4. |
- Hsu, D. S., et al.
(författare)
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FLOW LINEAR DICHROISM AND ELECTRON-MICROSCOPIC ANALYSIS OF PROTEIN-DNA COMPLEXES OF A MUTANT UVRB PROTEIN THAT BINDS TO BUT CANNOT KINK DNA
- 1994
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 241:5, s. 645-650
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Tidskriftsartikel (refereegranskat)abstract
- (A)BC excinuclease of Escherichia coli is the enzymatic activity resulting from sequential and partially overlapping actions of UvrA, UvrB, and UvrC protein. UvrA is a molecular matchmaker which promotes the formation of a stable UvrB-damaged DNA complex in which the DNA is kinked by about 130 degrees. The UvrB-DNA complex is then recognized by UvrC) and two incisions are made in the DNA by the joint actions of UvrC and UvrB. A mutant of UvrB (D478A) can be loaded onto the DNA but it does not interact with UvrC to cause a nick 3' to the lesion. Based on the lack of a DNase-I-hypersensitive site in the footprint of the mutant, it was proposed that the lack of incision was due to the inability of the mutant UvrB to kink the DNA. In the current study we have investigated the interaction of the mutant UvrB with DNA using two biophysical methods, flow linear dichroism and electron microscopy. Both methods reveal that the mutant UvrB is unable to bend DNA.
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| 5. |
- Linnarsson, Margareta K., et al.
(författare)
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Sputter profiling of AlGaAs/GaAs superlattice structures using oxygen and argon ions
- 1993
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 70-71:1, s. 40-43
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Tidskriftsartikel (refereegranskat)abstract
- Broadening of Al sputter profiles in AlxGa1-xAs/GaAs structures has been investigated using secondary ion mass spectrometry. The depth profiling was carried out with 32O+2 ions and 40Ar+ ions using net primary energies of 1.8, 2.2, 3.2 and 5.7 keV. The decay lengths of the Al profiles show a pronounced increase with increasing sputtering ion energy caused by ballistic mixing. Moreover, in the O+2 case the λ-values degrade with eroded depth, indicating that beam-induced surface roughening takes place during profiling and in particular, this holds for high x-values. The results are discussed in terms of a semi-empirical model for ion-beam-induced broadening developed by Zalm and Vriezema.
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| 6. |
- Ye, F.M., et al.
(författare)
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Turbine governing and surge-tank stability
- 1992
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Ingår i: Journal of Hydraulic Research. - 0022-1686 .- 1814-2079. ; 30:1
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Tidskriftsartikel (refereegranskat)abstract
- The stability of water-surface oscillations is investigated for the case of a tailrace surge chamber shared by two or more generating units in a hydroelectric power plant. Two kinds of turbine governing are applied for the condition of small-amplitude surge perturbations. Critical stability conditions for the surge chamber are derived by linearizing the ordinary differential equations describing the lumped system. As compared with the result achieved by previous researchers, the common surge chamber requires smaller horizontal crosssection for surge stability. A combination of the proposed manners of governing can be utilized in certain power plants in order to achieve an economical design of the surge chambers.
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