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- Bergstrom, R, et al.
(författare)
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Comparative study of DFT methods applied to small titanium oxygen compounds
- 1996
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Ingår i: INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY. - 0020-7608. ; 59:6, s. 427-443
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The performance of a number of different local and nonlocal density functional theory (DFT) methods has been investigated for some small titanium-oxygen systems. Equilibrium geometries, ionization potentials, dipole moments, atomization energies, and harm
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| 5. |
- Eriksson, LA
(författare)
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Sulfinylimine radical in azido-CDP- and azido-UDP-inhibited ribonucleotide reductase
- 1998
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Ingår i: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY. - 0002-7863. ; 120:32, s. 8051-8054
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The equilibrium geometry and protonation state of a model of the sulfinylimine type radical observed in the reaction between the modified substrate 2'-azido-2'-deoxyribonucleotide-5'-diphosphate and a cysteine radical at the active site of ribonucleotide
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| 14. |
- Fangstrom, T, et al.
(författare)
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Theoretical study of the insertion reactions of aluminum with H2O, NH3, HCl, and Cl-2
- 1998
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY A. - 1089-5639. ; 102:6, s. 1005-1017
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Stationary points on the potential energy surfaces describing the reactions between Al and H2O, NH3, HCl, and Cl-2 respectively, have been optimized at the ab initio MP2 and QCISD levels as well as by density functional theory (DFT) using the B3LYP functi
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| 15. |
- Himo, F, et al.
(författare)
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Conformational analysis of quinone anion radicals in photosystem II and photosynthetic bacteria
- 1999
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY A. - 1089-5639. ; 103:19, s. 3745-3749
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Using density functional theory (DFT) techniques, we have investigated possible conformers of the radical anions of plastoquinone (psQ), ubiquinone (ubQ), and menaquinone (mnQ), which are formed in the reaction centers of photosynthetic bacteria, blue-gre
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| 16. |
- Himo, F, et al.
(författare)
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On the local structure of the glycyl radical in different enzymes
- 1998
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Ingår i: JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2. - 0300-9580. ; :2, s. 305-308
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Full hyperfine coupling tensors are computed for different geometric conformers of the glycyl radical, using gradient corrected Density Functional Theory (DFT) together with large basis sets (IGLO-III). Comparison is made with three enzymes in which the r
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| 17. |
- Himo, F, et al.
(författare)
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Tyrosyl radical in galactose oxidase not strongly perturbed by cysteine cross-link
- 1999
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Ingår i: CHEMICAL PHYSICS LETTERS. - 0009-2614. ; 313:1-2, s. 374-378
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Several density functional methods are applied to calculate the hyperfine coupling constants and spin population distributions of sulfur-substituted and unsubstituted tyrosyl radical. The cysteine-substituted tyrosyl radical is found at the active site of
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| 21. |
- Salhi-Benachenhou, Nessima, et al.
(författare)
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Formation of 2-hexene by cationic dimerization of propene : an ab initio and density functional theory study
- 1997
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Ingår i: Theoretical Chemistry accounts. - : Springer Science and Business Media LLC. - 1432-881X .- 1432-2234. ; 97:1-4, s. 277-282
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Tidskriftsartikel (refereegranskat)abstract
- The formation of a 2-hexene radical cation from a propene radical cation and a neutral propene molecule is investigated by means of ab initio UHF and spin projected MP2 calculations, as well as the SVWN and B3LYP levels of density functional theory. A stable addition complex, with loose CC bonds, is found. To proceed from the addition complex to the product. a locally planar transition state must be passed, with a migrating hydrogen located half-way between the donating and the accepting carbon atoms. At the highest computational levels considered, PMP2/6-31G(d,p)//MP2/3-21G and B3LYP/6-31G(d,p), this transition state lies approximately 11 and 13 kcal/mol, respectively above the addition complex. The high barrier is believed to be one reason why radical cation oligomerization of propene has not been detected experimentally, in contrast to the case of ethene, where the corresponding barrier is only a few kcal/mol.
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| 22. |
- Sundin, Anders, et al.
(författare)
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Whole-body PET with [11C]-5-hydroxytryptophan for localization of neuroendocrine tumors
- 1999
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Ingår i: Clinical Positron Imaging. - 1095-0397 .- 1878-5751. ; 2:6, s. 338-
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: [11C]-5-Hydroxytryptophan (5-HTP) has previously been shown to be an excellent tracer for localization of neuroendocrine tumors, especially hormone-producing midgut carcinoids. To improve the clinical usefulness of 5-HTP PET in a diagnostic setting, we wanted to develop a whole-body scanning approach.Methods: The patients received 200 mg carbidopa orally as premedication to block physiological decarboxylation, thereby improving tumor/background contrast. Two hundred to 800 MBq of 5-HTP was injected in a forearm vein. Ten minutes post-injection emission scanning was performed, covering thorax and abdomen in whole-body mode. In a GE4096 scanner (10 cm FOV), a protocol of up to 6 bed positions with timeframes of 5, 7, 10, 10, 15, and 20 minutes was used. In a Siemens CTI Ecat HR+ scanner (15.5 cm FOV), 4 bed positions with timeframes of 7, 10, 15, and 20 minutes was used. Transmission scans were performed for 2–4 minutes for each bed position and segmented for attenuation correction. Comparison with CT, octreotide scintigraphy, and surgical end points were made.Results: So far 50 patients referred for staging of carcinoid tumors, localization of ectopic ACTH-producing tumors or endocrine pancreatic tumors have been investigated. 5-HTP generally shows more lesions than CT and in some cases more lesions and lesions at an earlier stage than octreotide scintigraphy. Clinical trials have been set up to define the role of 5-HTP whole-body scans in routine clinical use.Conclusions: Whole-body PET with 5-HTP is a promising new approach in diagnostic imaging of neoplasias of neuroendocrine origin, evidently changing treatment planning in selected patient groups. (Clin Pos Imag 1999;2:338) All rights reserved.
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| 23. |
- Werst, DW, et al.
(författare)
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Hydrogen atom addition to hydrocarbon guests in radiolyzed zeolites
- 1999
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY B. - 1089-5647. ; 103:43, s. 9219-9230
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The formation of H adducts during radiolysis of zeolites containing olefinic and aromatic hydrocarbon guests was demonstrated to occur by H atom transfer from the zeolite to the adsorbed molecules. The H adducts and other paramagnetic radiolysis products
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| 27. |
- Wetmore, SD, et al.
(författare)
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Theoretical investigation of adenine radicals generated in irradiated DNA components
- 1998
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY B. - 1089-5647. ; 102:51, s. 10602-10614
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Density functional theory is used to investigate various hydrogenated, dehydrogenated, and hydroxylated radicals formed upon irradiation of adenine. The relative energies, geometries, and hyperfine coupling constants of possible radicals are discussed. Th
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