| 1. |
- Ahlberg, E., et al.
(författare)
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The surface oxidation of pyrite in alkaline solution
- 1990
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Ingår i: Journal of Applied Electrochemistry. - 0021-891X .- 1572-8838. ; 20:6, s. 1033-1039
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Tidskriftsartikel (refereegranskat)abstract
- The collector-less flotation of pyrite has been studied by conventional techniques and is correlated to the electrochemical behaviour of pyrite in alkaline solution (1m NaClO4, pH 11). It was concluded that the initial oxidation of pyrite produces a hydrophobic sulphur rich surface together with hydrophilic iron hydroxide species. Also upon grinding, the surface is covered by hydrophilic species and therefore no significant flotation was obtained in the absence of a collector. However, collectorless flotation was readily obtained in an iron complexing solution like EDTA. This indicates that the remaining sulphur-rich layer is responsible for the floatability of pyrite under these conditions.
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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- Shahnavaz, Houshang, et al.
(författare)
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A usability evaluation of text and speech redundant help messages on a reader interface
- 1993
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Ingår i: Human-computer interaction. - Amsterdam : Elsevier. - 044489540X ; , s. 724-729
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study is to investigate whether text and speech redundant help messages are more usable than non-redundant messages on a reader interface. This paper looks at the principles underlying multi-media. The hypothesis is that if a speech and text redundant message is presented on a reader interface, then the users should have less difficulties or errors and shorter performance time in such tasks, by using such a (redundant) interface than using the text interface or speech interface. Four evaluation tools, i.e., observations, subjective ratings, interviews, and objective performance measures, were used to evaluate the effects of the messages. Twenty subjects (9 males and 11 females) from the general public participated in the study. The results partly support our hypothesis by showing that the redundant interface is the easiest and quickest among the three in terms of learning and using. Appropriate use of text and speech redundant help messages does contribute to the usability of the reader interface for the tested condition. However, the adverse effects of the speech, e.g., repeat messages are annoying, must be dealt with care.
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| 6. |
- Wang, L P, et al.
(författare)
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Auditory function after spinal anesthesia
- 1993
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Ingår i: Regional Anesthesia. - 0146-521X. ; 18:3, s. 5-162
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To determine the effect of spinal anesthesia using 26-gauge needles on hearing.METHODS: Eighteen male patients undergoing transurethral resection of the prostate (TURP) or other transurethral procedures under spinal or epidural anesthesia were studied prospectively to reveal possible auditory side effects of dural puncture or absorption of irrigation fluid to the blood stream. Measurement of auditory function by pure tone, Bekesy and speech audiometry, and measurement of serum concentrations of sodium, potassium, urea, and glucose were performed preoperatively and postoperatively. Clinical examination of cranial nerve functions was performed postoperatively.RESULTS: No mean change in hearing ability was seen in any group. One patient had severe, transient, low-frequency hearing loss with simultaneous severe postdural puncture headache. A statistically significant postoperative fall in serum osmolarity was noted in the epidural TURP group.CONCLUSION: Transient, severe hearing loss may still occur after spinal anesthesia using a 26-gauge needle. Minor hearing loss does not seem to be a problem with this needle size.
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| 7. |
- Wang, Y, et al.
(författare)
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Functional homology between N-myc and c-myc in murine plasmacytomagenesis : plasmacytoma development in N-myc transgenic mice
- 1992
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Ingår i: Oncogene. - 0950-9232. ; 7:6, s. 7-1241
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Tidskriftsartikel (refereegranskat)abstract
- Mouse plasmacytomas induced by pristane oil alone, or in combination with Abelson murine leukemia virus (A-MuLV), regularly carry one of three alternative chromosomal translocations that juxtapose c-myc to immunoglobulin heavy- or light-chain loci. E mu-c-myc transgenic mice develop translocation-free plasmacytomas after induction by pristane oil and/or A-MuLV [Sugiyama, H., Silva, S., Wang, Y., Weber, G., Babonits, M., Rosen, A., Wiener, F. & Klein, G. (1990). Int. J. Cancer, 46, 845-852]. In order to test whether another member of the myc family, N-myc, could play a similar role as c-myc, we treated E mu-N-myc transgenic mice with pristane and helper-free A-MuLV. Of 20 mice that received a single pristane injection followed by A-MuLV, 17 developed plasmacytomas with a mean latency period of 54 +/- 20 days. In a corresponding group that only received a single pristane injection, five out of six transgenic mice developed plasmacytomas with a mean latency period of 142 +/- 32 days. However, after three monthly injections of pristane, all 15 transgenic mice developed plasmacytomas with a mean latency period of 128 +/- 20 days. All plasmacytomas expressed the N-myc transgene, while none of them expressed either c-myc or endogenous N-myc. None of the tumors carried the usual plasmacytoma-associated translocations.
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| 8. |
- Wang, Y, et al.
(författare)
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Reconstitution of wild-type p53 expression triggers apoptosis in a p53-negative v-myc retrovirus-induced T-cell lymphoma line
- 1993
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Ingår i: Cell Growth & Differentiation. - 1044-9523. ; 4:6, s. 73-467
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Tidskriftsartikel (refereegranskat)abstract
- Inactivation or mutation of the p53 tumor suppressor gene has been observed in a wide variety of human and murine tumors. We have found that a v-myc retrovirus (J3)-induced T-cell lymphoma line (J3D) has lost one of its p53 alleles, whereas the other has become inactivated due to the insertion of a Moloney murine leukemia provirus in intron 4 with an opposite transcriptional orientation. No p53 protein could be detected by immunoprecipitation with monoclonal anti-p53 antibodies. We have transfected this line with the temperature-sensitive murine Val135 construct that is expressed as mutant p53 at 37 degrees C and largely wild-type p53 at 32 degrees C. There was no difference in the number of viable cells among the p53 transfectants, the parental cells, and neomycin vector-transfected control cells at 37 degrees C. Following a temperature shift to 32 degrees C, the p53 transfectants rapidly lost viability, and 95-100% of the cells were dead by 3 days, whereas the control cells remained unaffected. Examination of DNA isolated from p53-transfected cells grown at 32 degrees C revealed nucleosomal fragmentation, indicating cell death by apoptosis. It is suggested that apoptosis is triggered by contradictory signaling. Constitutively expressed v-myc can stimulate cell proliferation, whereas expression of wild-type p53 in cells that have lost endogenous p53 expression in the course of their neoplastic development may suppress growth.
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