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| 2. |
- Behravan, G., et al.
(författare)
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THE INTERACTION OF ELLIPTICINE DERIVATIVES WITH NUCLEIC-ACIDS STUDIED BY OPTICAL AND H-1-NMR SPECTROSCOPY - EFFECT OF SIZE OF THE HETEROCYCLIC RING
- 1994
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Ingår i: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 34:5, s. 599-609
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Tidskriftsartikel (refereegranskat)abstract
- The DNA interaction of derivatives of ellipticine with heterocyclic ring systems with three, four, or five rings and a dimethylaminoethyl side chain was studied. Optical spectroscopy of drug complexes with calf thymus DNA, poly [(dA-dT).(dA-dT)], or poly [(dG-dC).(dG-dC)] showed a 10 nm bathochromic shift of the light absorption bands of the pentacyclic and tetracyclic compounds upon binding to the nucleic acids, which indicates binding by intercalation. For the tricyclic compound a smaller shift of 1-3 nm was observed upon binding to the nucleic acids. Flow linear dichroism studies show that the geometry of all complexes is consistent with intercalation of the ring system, except for the DNA and poly [(dG-dC).(dG-dC)] complexes of the tricyclic compound, where the average angle between the drug molecular plane and the DNA helix axis was found to be 65 degrees. One-dimensional H-1-nmr spectroscopy was used to study complexes between d(CGCGATCGCG)(2) and the tricyclic and pentacyclic compounds. The results on the pentacyclic compound show nonselective broadening due to intermediate chemical exchange of most oligonucleotide resonances upon drug binding. The imino proton resonances are in slow chemical exchange, and new resonances with upheld shifts approaching 1 ppm appear upon drug binding, which supports intercalative binding of the pentacyclic compound. The results on the tricyclic compound show more rapid binding kinetics and very selective broadening of resonances. The data suggest that the tricyclic compound is in an equilibrium between intercalation and minor groove binding, with a preference to bind close to the AT base pairs with the side chain residing in the minor groove. (C) 1994 John Wiley and Sons, Inc.
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| 4. |
- Doe, T.W., et al.
(författare)
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Determination of the state of stress at the Stripa Mine, Sweden
- 1982
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Ingår i: Workshop on Hydraulic Fracturing Stress Measurements. - Menlo Park, Calif.
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Konferensbidrag (refereegranskat)abstract
- The state of stress at the Stripa Mine has been measured both in a 381-m-deep hole drilled from the surface and in holes drilled from the drifts underground. Hydraulic fracturing and several overcoring methods have been used (Lulea triaxial gauge, CSIRO gauge, USBM gauge, Swedish State Power Board deep-hole Leeman triaxial gauge). Propagation of the hydraulic fractures underground was monitored acoustically in an attempt to determine the location and orientation of the fractures. The results of overcoring and hydraulic fracturing agree well, particularly for the magnitude and orientation of the greatest stress. The hydraulic-fracturing data were interpreted using first-breakdown pressures and tensile-strength values determined using statistical fracture mechanics. Shut-in pressure values were obtained from semi-logarithmic plots of the post-breakdown pressure decay and from reopening the fractures at low pumping rates.
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| 5. |
- Doe, T.W., et al.
(författare)
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Results and conclusions of stress measurements at Stripa
- 1983
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Konferensbidrag (refereegranskat)abstract
- This paper describes the results of stress measurements at Stripa, compares the results obtained by different techniques, and recommends a stress measurement program for a hard rock repository site. The state of stress at the Stripa Mine has been measured both in a 381-m-deep hole drilled from the surface and in holes drilled from the drifts underground. Hydraulic fracturing and several overcoring methods have been used (Lulea triaxial gauge, CSIRO gauge, USBM gauge, Swedish State Power Board deep-hole Leeman triaxial gauge). The results of overcoring and hydraulic fracturing agree well, particularly for the magnitude and orientation of the greatest stress. A recommended program for stress measurement at a repository site would include hydraulic fracturing and deep-hole overcoring in a deep hole drilled from surface, and overcoring (Lulea gauge and USBM gauge) and hydraulic fracturing from holes drilled from underground openings when access is available. Propagation of the hydraulic fractures should be monitored acoustically to determine their location and orientation.
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| 6. |
- Eriksson, M., et al.
(författare)
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BINDING OF DELTA- RU(PHEN)(3) (2+) AND LAMBDA- RU(PHEN)(3) (2+) TO D(CGCGATCGCG) (2) STUDIED BY NMR
- 1994
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 1520-4995 .- 0006-2960. ; 33:17, s. 5031-5040
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Tidskriftsartikel (refereegranskat)abstract
- The interactions of the Delta and Delta enantiomers of the chiral metal complex [Ru(phen)(3)](2+) (phen = 1,10-phenanthroline) with the oligonucleotide duplex [d(CGCGATCGCG)](2) have been studied with NMR and CD spectroscopy. From NOESY data it is shown that the interaction primarily takes place in the minor groove of the oligonucleotide which remains in a B-like conformation. The observed NOEs also provide evidence that the metal complexes preferentially bind to the central AT region. The observed AT specificity is more pronounced with the Delta as compared to the Delta enantiomer, which interacts with a larger part of the oligonucleotide. Furthermore, the NOESY data show that neither of the enantiomers binds by classical intercalation. This is also supported by a comparison study of the analogue [Ru(phen)(2)DPPZ](2+) (DPPZ = dipyrido[ 3,2-a:2',3'-c] phenazine) which intercalates in DNA. The NMR as well as the CD results show that the Delta and Delta enantiomers of [Ru(phen)(3)](2+) bind in different modes to [d(CGCGATCGCG)](2). Comparison of CD spectra of the metal complex in the presence of [d(CGCGATCGCG)](2), poly(dAdT).poly(dAdT), poly(dGdC).poly(dGdC), and calf thymus DNA suggests that these binding modes are independent of DNA sequence. The results are found to be compatible with binding of Delta-[Ru(phen)(3)](2+) by insertion of two phenanthroline ligands into the minor groove, causing minor distortions of the DNA structure, whereas the Delta enantiomer binds in a mode that leaves the DNA structure unaffected.
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| 8. |
- Gregory, E.C., et al.
(författare)
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An assessment of the suitability of five overcoring techniques for stress determination in a jointed basalt
- 1983
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Rapport (refereegranskat)abstract
- deformation gauge, the C.S.I.R.O. hollow inclusion stress cell, the cast epoxy inclusion, the Lulea triaxial strain cell, and the C.S.I.R. doorstopper'' gauge to assess the suitability of each technique for in situ stress determination in a closely jointed basalt. This effort is in support of the Basalt Waste Isolation Project which is studying the feasibility of locating a nuclear waste repository in basalt. Testing at the NSTF provided information for the evaluation of overcoring techniques so that one or more can be selected to obtain in situ stress data at the reference repository horizon. Even though some problems were experienced, the borehole deformation gauge and doorstopper proved the most successful. 30 refs., 53 figs. 16 tabs.
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| 9. |
- Leijon, Bengt A., et al.
(författare)
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A comparative study between two rock stress measurement techniques at Luossavaara Mine
- 1986
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Ingår i: Rock Mechanics and Rock Engineering. - 0723-2632 .- 1434-453X. ; 19:3, s. 143-163
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Tidskriftsartikel (refereegranskat)abstract
- As part of a comprehensive geomechanical pre-investigation scheme, rock stress measurements were conducted at four locations, representing three different rock types, in the Luossavaara Mine, located within the Kiruna iron ore fields in northern Sweden. Two similar triaxial overcoring techniques, the CSIRO Hollow Inclusion Technique and the LUH Triaxial Technique, were used in a parallel fashion in order to obtain redundant results, but also with the intention of comparing the field applicability of the two methods. The results show that the state of stress is characterized by a sub-horizontally directed maximum stress with a magnitude of about 10 MPa. The agreement in terms of stress results between the two methods was generally good. The study demonstrated that the technical differences between the two devices used were of little significance as compared to the observed, often non-ideal mechanical characteristics of the rock. The latter added considerable uncertainty to the data, regardless of the measuring technique used, and it is therefore concluded that the rock quality is a major factor in the application of any overcoring method. Finally, it was shown that the biaxial test method, which is frequently used for the determination of rock properties in connection with stress measurements, is not always relevant for this purpose.
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| 10. |
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| 11. |
- Leijon, M., et al.
(författare)
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STRUCTURAL CHARACTERIZATION OF PNA-DNA DUPLEXES BY NMR - EVIDENCE FOR DNA IN A B-LIKE CONFORMATION
- 1994
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 1520-4995 .- 0006-2960. ; 33:33, s. 9820-9825
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Tidskriftsartikel (refereegranskat)abstract
- The nucleic acid analogues PNA (peptide nucleic acids) hybridize with DNA of complementary sequence. The solution structures of two PNA-DNA duplexes, H-(GCTATGTC)-NH2.d(GACATAGC) and H-(GTAGATCACT)-NH2.d(AGTGATCTAC), have been studied by H-1 NMR. It was found that the PNA-DNA hybrids are base paired by hydrogen bonds, most likely of the Watson-Crick type. From two-dimensional NOESY and COSY results it is concluded that the DNA strand in the PNA-DNA complex adopts a B-like structure with the deoxyribose sugars in the C2'-endo conformation.
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