| 1. |
- Dunham, I, et al.
(author)
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The DNA sequence of human chromosome 22
- 1999
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 402:6761, s. 489-495
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Journal article (peer-reviewed)
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| 2. |
- Nguyen, Son Tien, 1953-, et al.
(author)
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Electron-paramagnetic-resonance studies of defects in electron-irradiated p-type 4H and 6H SiC
- 1999
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In: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 273-274, s. 655-658
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Journal article (peer-reviewed)abstract
- Defects in p-type 4H and 6H SiC irradiated by 2.5 MeV electrons were studied by electron paramagnetic resonance (EPR). Two anisotropic EPR spectra, labeled I and II, were observed in both 4H and 6H SiC. These spectra demonstrating triclinic symmetry of the center can be described by an effective electron spin S=1/2. The angle α between the direction of the principal gz of the g-tensors and the c-axis is determined as 63° and 50° for spectra I and II, respectively. In the 6H polytype, a third also similar EPR spectrum was detected. Based on their similarity in the electronic structure (electron spin, symmetry, g values), annealing behavior and temperature dependence, these spectra are suggested to be related to the same defect occupying different inequivalent lattice sites in 4H and 6H SiC. A pair between a silicon vacancy and an interstitial is a possible model for the defect.
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| 3. |
- Hemmingsson, Carl, 1964-, et al.
(author)
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Deep-Level Defects in Electron-irradiated 4H SiC Epitaxial Layers
- 1997
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 81:9, s. 6155-6159
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Journal article (peer-reviewed)abstract
- Deep level defects in electron-irradiated 4H SiC epitaxial layers grown by chemical vapor deposition were studied using deep level transient spectroscopy. The measurements performed on electron-irradiated p+n junctions in the temperature range 100–750 K revealed several electron traps and one hole trap with thermal ionization energies ranging from 0.35 to 1.65 eV. Most of these defects were already observed at a dose of irradiation as low as ≈5×1013 cm-2. Dose dependence and annealing behavior of the defects were investigated. For two of these electron traps, the electron capture cross section was measured. From the temperature dependence studies, the capture cross section of these two defects are shown to be temperature independent. © 1997 American Institute of Physics.
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| 4. |
- Kim, S.K., et al.
(author)
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Binding Geometries of Triple Helix Selective Benzopyrido [4,3-b]indole Ligands Complexed with Double- and Triple-Helical Polynucleotides
- 1997
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In: Biopolymers. - 0006-3525 .- 1097-0282. ; 42:1, s. 101-111
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Journal article (peer-reviewed)abstract
- The binding modes of three benzopyrido[4,3-b]indole derivatives (and one benzo[f]pyrido[4-3b]quinoxaline derivative) with respect to double helical poly(dA) . poly(dT) and poly[d(A-T)](2) and triple-helical poly(dA) . 2poly(dT) have been investigated using linear dichroism (LD) and CD: (I) 3-methoxy-11-amino-BePI where BePI = {7H-8-methyl-benzo[e]pyrido[4,3-b]indole}, (II) 3-methoxy-11-[(3'-amino)propylamino]-BePI, (III) 3-methoxy-7-[(3'diethylamino)propylamino]BgPI where BgPI = {benzo[g]pyrido[4,3-b]indole}, and (IV) 3-methoxy-11-[(3'amino)propylamino]BfPQ where BfPQ = {benzo[f]pyrido[4-3b]quinoxaline}. The magnitudes of the reduced LD of the electronic transitions of the polynucleotide bases and of the bound ligands are generally very similar, suggesting an orientation of the plane of the ligands' fused-ring systems preferentially perpendicular to the helix axis. The LD results suggest that all of the ligands are intercalated for all three polynucleotides. The induced CD spectrum of the BePI chromophore in the (II-BePI)-poly[d(A-T)](2) complex is almost a mirror image of that for the (I-BePI)-poly(dA) . poly(dT) and (I-BePI)-poly(dA) . 2poly(dT) complexes, suggesting an antisymmetric orientation of the BePI moiety upon intercalation in poly[d(A-T)]2 compared to the other polynucleotides. The induced CD of I-BePI bound to poly(dA) . 2poly(dT) suggests a geometry that is intermediate between that of its other two complexes. The concluded intercalative binding as well as the conformational variations between the different BePI complexes are of interest in relation to the fact that BePI derivatives are triplex stabilizers.
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| 5. |
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| 6. |
- Nguyen, HN, et al.
(author)
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Abnormal postprandial duodenal chyme transport in patients with long standing insulin dependent diabetes mellitus
- 1997
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In: Gut. - : BMJ. - 0017-5749 .- 1468-3288. ; 41:5, s. 624-631
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Journal article (peer-reviewed)abstract
- AbstractBackground—Patients with long standing diabetes mellitus frequently have upper gut dysmotility. Gastroparesis has been well studied, whereas detailed data on duodenal motor function are limited.Aims—To characterise postprandial duodenal chyme transport in such patients.Methods—Intraluminal multiple impedance measurement, recently introduced as a novel technique for investigation of chyme transport, was used to study postprandial duodenal chyme flow in 10 patients with long standing insulin dependent diabetes mellitus with gastroparesis, and 10 healthy volunteers.Results—Four distinct transport patterns of chyme, termed bolus transport events (BTEs), were found in both groups and could be characterised as: short distance propulsive; simple long distance propulsive; retrograde; and complex long distance propulsive. Diabetic patients had significantly lower numbers of propulsive BTEs (p<0.01), and higher proportions of retrograde BTEs and complex long distance BTEs (p<0.05) than control subjects, whereas the proportion of simple long distance BTEs was significantly lower (p<0.05). The mean propagation velocities of the BTEs were similar in both groups.Conclusion—Abnormal postprandial duodenal chyme transport was found in patients with long standing insulin dependent diabetes mellitus. This is characterised by transport disorganisation and may result in disturbed chyme clearance.
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| 7. |
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| 8. |
- Nguyen, Son Tien, 1953-, et al.
(author)
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A complex defect related to the carbon vacancy in 4H and 6H SiC
- 1999
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In: Physica Scripta. - 0031-8949 .- 1402-4896. ; T79, s. 46-49
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Journal article (peer-reviewed)abstract
- Electron paramagnetic resonance (EPR) was used to study defects in 4H and 6H SiC irradiated with 2.5 MeV electrons at room temperature. When the dose of irradiation reaches ~ 5 × 1017 electrons/cm2, an EPR spectrum appears. In both 4H and 6H SiC, the defect associated with this spectrum has C1h symmetry with an effective electron spin S = 1 and an isotropic g-value of 2.0063 ± 0.0002. The crystal-field parameter was determined as D = 1.65 and D = 1.67 GHz for 4H and 6H SiC, respectively. The principal crystal-field axis lies in the (11bar 20) plane and makes an angle of ~ 46° with the c-axis for both polytypes. A clear hyperfine structure from 29Si due to the interaction with four nearest silicon neighbours was observed, confirming that the defect is related to the carbon vacancy. The similarity in all respects including the annealing behaviour of the spectrum in both polytypes suggests that it belongs to the same defect. Based on the formation and its electronic structure, the defect is suggested to be a complex with one of the components being the carbon vacancy.
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| 9. |
- Nguyen, Son Tien, 1953-, et al.
(author)
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Carbon-vacancy related defects in 4H- and 6H-SiC
- 1999
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In: Materials Science and Engineering B, Vol. 61-62. - : Elsevier. ; , s. 202-
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Conference paper (peer-reviewed)abstract
- Electron paramagnetic resonance (EPR) was used to study intrinsic defects in 4H- and 6H-SiC irradiated with 2.5 MeV electrons with doses ranging from 1×1017 to 2×1018 cm−2. In p-type 4H- and 6H-SiC, the dominant EPR signal, labeled EI1, associates with a defect centre having a low symmetry and an effective electron spin S=1/2. For both polytypes, its g-tensor was determined as gz=2.0015, gx=1.9962 and gy=2.0019, where gz and gx lie in the (11Image 0) plane and the z-axis makes an angle not, vert, similar41 degrees with the c-axis. Hyperfine interaction with a 29Si atom located at two equivalent sites in the nearest neighbour shell was detected, confirming that the defect resides at the carbon site. In heavily irradiated 4H- and 6H-SiC, a new EPR spectrum having an electron spin S=1, labeled EI3, was observed. In both polytypes, the EI3 centre has a low symmetry, an isotropic g-value of 2.0063 and a fine structure parameter |D|not, vert, similar5.5×10−2 cm−1. The observed hyperfine interaction with four 29Si atoms in the nearest neighbour shell confirms the involvement of the carbon vacancy in the defect. The defect is suggested to be a complex centre involving a carbon vacancy.
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