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- Brinck, Tore, et al.
(author)
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Segmental analysis of molecular surface electrostatic potentials : application to enzyme inhibition
- 2003
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In: Journal of Molecular Modeling. - : Springer Science and Business Media LLC. - 1610-2940 .- 0948-5023. ; 9:2, s. 77-83
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Journal article (peer-reviewed)abstract
- We have recently shown that the anti-HIV activities of reverse transcriptase inhibitors can be related quantitatively to properties of the electrostatic potentials on their molecular surfaces. We now introduce the technique of using only segments of the drug molecules in developing such expressions. If an improved correlation is obtained for a given family of compounds, it would suggest that the segment being used plays a key role in the interaction. We demonstrate the procedure for three groups of drugs, two acting on reverse transcriptase and one on HIV protease. Segmental analysis is found to be definitely beneficial in one case, less markedly so in another, and to have a negative effect in the third. The last result indicates that major portions of the molecular surfaces are involved in the interactions and that the entire molecules need to be considered, in contrast to the first two examples, in which certain segments appear to be of primary importance. This initial exploratory study shows that segmental analysis can provide insight into the nature of the process being investigated, as well as possibly enhancing the predictive capability.
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| 5. |
- Jin, P., et al.
(author)
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Computational prediction of relative group polarizabilities
- 2003
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In: International Journal of Quantum Chemistry. - : Wiley. - 0020-7608 .- 1097-461X. ; 95:05-apr, s. 632-637
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Journal article (peer-reviewed)abstract
- Earlier work has shown that molecular polarizabilities correlate well with the quantity V/(I) over bar (S,ave), where V is the volume of the molecule and (I) over bar (S,ave) is the average value of the local ionization energy on its surface. We now extend this to group polarizabilities; we computed V/(I) over bar (S,ave) for four common chemical groups (NO2, CH3, NH2, and OH) in a variety of molecules. The transferabilities of (I) over bar (S,ave), V, and V/(I) over bar (S,ave) are examined, as well as the correlation between V/(I) over bar (S,ave) and literature polarizabilities of CH3, NH2, and OH. This permits the value for NO2 to be predicted (alpha = 2.77 Angstrom(3)). The dependence of (I) over bar (S,ave), and therefore V/(I) over bar (S,ave), upon the remainder of the molecule is discussed.
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| 7. |
- Jin, YP, et al.
(author)
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Predicting multiple sclerosis at optic neuritis onset
- 2003
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In: Multiple sclerosis (Houndmills, Basingstoke, England). - : SAGE Publications. - 1352-4585 .- 1477-0970. ; 9:2, s. 135-141
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Journal article (peer-reviewed)abstract
- Using multivariate analyses, individual risk of clinically definite multiple sclerosis (C DMS) after monosymptomatic optic neuritis (MO N) was quantified in a prospective study with clinical MO N onset during 1990 -95 in Stockholm, Sweden. During a mean follow-up time of 3.8 years, the presence of MS-like brain magnetic resonance imaging (MRI) lesions and oligoclonal immunoglobulin (Ig) G bands in cerebrospinal fluid (CSF) were strong prognostic markers of C DMS, with relative hazard ratios of 4.68 {95% confidence interval (CI) 2.21 -9.91} and 5.39 (95% C I 1.56 -18.61), respectively. Age and season of clinical onset were also significant predictors, with relative hazard ratios of 1.76 (95% C I 1.02 -3.04) and 2.21 (95% C I 1.13 -3.98), respectively. Based on the above two strong predicto rs, individual probability of C DMS development after MO N was calculated in a three-quarter sample drawn from a cohort, with completion of follow-up at three years. The highest probability, 0.66 (95% C I 0.48 -0.80), was obtained for individuals presenting with three or more brain MRI lesions and oligoclonal bands in the C SF, and the lowest, 0.09 (95% C I 0.02 -0.32), for those not presenting with these traits. Medium values, 0.29 (95% C I 0.13 -0.53) and 0.32 (95% C I 0.07 -0.73), were obtained for individuals discordant for the presence of brain MRI lesions and oligoclonal bands in the C SF. These predictions were validated in an external one-quarter sample.
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| 8. |
- Lerma, F., et al.
(author)
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Superdeformed bands in Sr80-83, Y82-84, Zr-83,Zr-84 : Transition quadrupole moments, moments of inertia, and configuration assignments
- 2003
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 67:4, s. 044310-
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Journal article (peer-reviewed)abstract
- Multiple superdeformed bands in the nuclei Sr80-83, Y82-84, and Zr-83,Zr-84 have been studied in a backed-target experiment, using the Gammasphere and the Microball 4pi detector arrays. For 15 bands in these nuclei, average transition quadrupole moments have been measured with high accuracy, using the Doppler-shift attenuation method. Among these are the newly observed superdeformed bands in Y-83,Y-84, which are isospectral with the bands in Sr-82,Sr-83. These isospectral bands have nearly identical transition quadrupole moments. Two of the bands in Sr-81 interact and cross transitions between them are observed. The present measurements place stringent conditions on configuration assignments for the bands obtained from two types of mean-field calculations, leading to a consistent understanding of the mass similar to80 superdeformed bands. The assignments for different bands arise from one or more nucleons occupying the N-0=5h(11/2) intruder orbital.
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| 10. |
- Wang, M., et al.
(author)
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Ethylene oligomerization by salen-type zirconium complexes to low-carbon linear alpha-oletins
- 2003
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In: Journal of Catalysis. - 0021-9517 .- 1090-2694. ; 220:2, s. 392-398
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Journal article (peer-reviewed)abstract
- A series of zirconium salen-type complexes were prepared by using ZrCl4 and sodium salts of the tetradentate Schiff base ligands. In combination with Et2AlCl, they displayed moderate to high catalytic activities in ethylene oligomerization under a pressure of 1.0-1.8 MPa at 150 degreesC in toluene. The main products are C-4-C-10 olefins with good selectivity to linear alpha-olefins. The turnover frequency (TOF) of catalyst system Zr(salen)Cl-2 (.) THF/Et2AlCl, under a pressure of 1.8 MPa and in an Al/Zr molar ratio of 300, was 4.93 x 10(4) h(-1) with a satisfactory selectivity to C-4-C-10 olefins (89%), and linear alpha-olefins accounted for 95%. The steric and conjugate effects of the ligands on ethylene oligomerization, as well as the effects of cocatalysts, the Al/Zr molar ratios, the reaction temperature, the ethylene pressure, and the lifetime of the catalysts were studied.
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