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- Gao, Aiping, et al.
(författare)
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Asymmetric oxidation of sulfides catalyzed by chiral (salen)Mn(III) complexes with a pyrrolidine backbone
- 2006
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Ingår i: Applied organometallic chemistry. - : Wiley. - 0268-2605 .- 1099-0739. ; 20:12, s. 830-834
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Tidskriftsartikel (refereegranskat)abstract
- Catalytic properties of a series of chiral (pyrrolidine salen)Mn(III) complexes for asymmetric oxidation of aryl methyl sulfides were evaluated. Moderate activity, good chemical selectivity and low enantioselectivity were attained with iodosylbenzene as a terminal oxidant. Enantioselectivity of sulfide oxidation was affected slightly by polar solvent and the sulfoxidation carried out in THF for thioanisole and in CH3CO2Et for electron-deficient sulfides gave better enatioselctivities. The addition of the donor ligand PPNO (4-phenylpyridine N-oxide) or MNO (trimethylamine N-oxide) only has a minor positive effect on the enantioselectivity. Also explored was the steric effect of the N-aza-substituent in the backbone of (pyrrolidine salen)Mn(III) complexes on the enantioselectivity of sulfide oxidation. The sulfides' access pathway is discussed based on the catalytic results.
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- Graslund, S, et al.
(författare)
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Protein production and purification
- 2008
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Ingår i: Nature methods. - : Springer Science and Business Media LLC. - 1548-7105 .- 1548-7091. ; 5:2, s. 135-146
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Jiang, Shi, et al.
(författare)
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Fe-S complexes containing five-membered heterocycles : novel models for the active site of hydrogenases with unusual low reduction potential
- 2007
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; :8, s. 896-902
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Tidskriftsartikel (refereegranskat)abstract
- Three biomimetic 2Fe2S complexes [{(mu-SCH2)(2)NCH2(2-C4H3O)}](Fe-2(CO)(6)) (6a), [{(mu-SCH2)(2) NCH2(2-C4H3S)}](Fe-2(CO)(6)) (6b) and [{(mu-SCH2)(2)NCH2(5-Br-2-C4H2S)}Fe-2(CO)(6)] (6c) were prepared as models for the active site of Fe-only hydrogenase by the convergent process from [(mu-S-2)Fe-2(CO)(6)] and N,N-bis(hydromethyl)-2-furan and thiophene. The structures of these complexes were identified spectroscopically and crystallographically. The electrochemical behavior of the complexes 6a and 6c was unique as they showed catalytic proton reduction with a low reduction potential at -1.13 and -1.09 V vs Fc/Fc(+), respectively, in the presence of HClO4.
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- Jiang, Shi, et al.
(författare)
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Preparation, characteristics and crystal structures of novel N-heterocyclic carbene substituted furan- and pyridine-containing azadithiolate Fe-S complexes
- 2007
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Ingår i: Polyhedron. - : Elsevier BV. - 0277-5387 .- 1873-3719. ; 26:7, s. 1499-1504
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Tidskriftsartikel (refereegranskat)abstract
- Two novel N-heterocyclic carbene disubstituted furan- and pyridine-containing azadithiolate Fe-only hydrogenase models (2 and 4) have been synthesized, and characterized by IR and H-1 NMR spectra and X-ray single crystal diffraction. Cyclic voltammetry (CV) experiments indicate that they show more negative reductive potentials at -2.53 V and -2.49 V, respectively versus the ferrocene/ferrocenium couple (Fc/Fc(+)) and are easier to capture proton attributing to the strong electron-donating ligand NHC. After the protonation under F3CCO2H the reductive potentials of 2 and 4 have 1.02 V and 0.77 V shifts, indicating the formation of Fe-H-Fe bond. The results also are confirmed by the data changes in IR spectra and the negative H signals are detected by 1H NMR spectra at -27 ppm and -55 ppm.
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- Liu, Bingbing, et al.
(författare)
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Effects of silver films with different nano-particle sizes on SERS of single-walled carbon nanotubes
- 2005
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Ingår i: Chemical Journal of the Chinese Universities. - 0251-0790. ; 26:10, s. 1930-1933
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Tidskriftsartikel (refereegranskat)abstract
- Surface-enhanced Raman scattering (SERS) spectra of single-walled carbon nanotubes (SWCNTs) on silver films with different nano-particle sizes from 20 to 100 nm deposited on quartz and glass substrates were studied systematically. The characteristic Raman spectral features of SWCNT G-band and D-band were analyzed. The two bands show a similar tendency with the change of nano-particle size of silver on quartz and glass substrates. The position and the intensity of the G-band are less sensitive to the films' silver particle sizes in the studied range, indicating that hexagonal carbon rings are stable and have a weak interaction with silver films. The shape of the D-band depends on the silver size. The smaller the silver particle size, the more the contribution of high frequency vibrations to the D-band, indicating that disorder carbon has a strong interaction with the active silver films.
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- Aucott, Rebecca, et al.
(författare)
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HP1-beta is required for development of the cerebral neocortex and neuromuscular junctions
- 2008
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Ingår i: Journal of Cell Biology. - : Rockefeller University Press. - 0021-9525 .- 1540-8140. ; 183:4, s. 597-606
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Tidskriftsartikel (refereegranskat)abstract
- HP1 proteins are thought to be modulators of chromatin organization in all mammals, yet their exact physiological function remains unknown. In a first attempt to elucidate the function of these proteins in vivo, we disrupted the murine Cbx1 gene, which encodes the HP1-beta isotype, and show that the Cbx1(-/-) null mutation leads to perinatal lethality. The newborn mice succumbed to acute respiratory failure, whose likely cause is the defective development of neuromuscular junctions within the endplate of the diaphragm. We also observe aberrant cerebral cortex development in Cbx1(-/-) mutant brains, which have reduced proliferation of neuronal precursors, widespread cell death, and edema. In vitro cultures of neurospheres from Cbx1(-/-) mutant brains reveal a dramatic genomic instability. Our results demonstrate that HP1 proteins are not functionally redundant and that they are likely to regulate lineage-specific changes in heterochromatin organization.
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- Clark, Andrew G., et al.
(författare)
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Evolution of genes and genomes on the Drosophila phylogeny
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 450:7167, s. 203-218
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Tidskriftsartikel (refereegranskat)abstract
- Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.
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