| 1. |
- Wang, Lin, et al.
(författare)
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Synthesis and high pressure induced amorphization of C60 nanosheets
- 2007
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 91:10, s. 103112-
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Tidskriftsartikel (refereegranskat)abstract
- C-60 nanosheets with thicknesses in the nanometer range were synthesized by a simple method. Compared to bulk C-60, the lattice of the nanosheets is expanded by about 0.4%. In situ Raman spectroscopy and energy-dispersive x-ray diffraction under high pressures have been employed to study the structure of the nanosheets. The studies indicate that the bulk modulus of the C-60 nanosheets is significantly larger than that of bulk C-60. The C-60 cages in nanosheets can persist at pressures over 30 GPa, 3 GPa higher than for bulk C-60. These results suggest that C-60 crystals in even small size will be a potential candidate of superhard materials.
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| 2. |
- 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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| 3. |
- Aspholm, Marina, et al.
(författare)
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SabA is the H. pylori hemagglutinin and is polymorphic in binding to sialylated glycans.
- 2006
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Ingår i: PLoS pathogens. - : Public Library of Science (PLoS). - 1553-7374 .- 1553-7366. ; 2:10
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Tidskriftsartikel (refereegranskat)abstract
- Adherence of Helicobacter pylori to inflamed gastric mucosa is dependent on the sialic acid-binding adhesin (SabA) and cognate sialylated/fucosylated glycans on the host cell surface. By in situ hybridization, H. pylori bacteria were observed in close association with erythrocytes in capillaries and post-capillary venules of the lamina propria of gastric mucosa in both infected humans and Rhesus monkeys. In vivo adherence of H. pylori to erythrocytes may require molecular mechanisms similar to the sialic acid-dependent in vitro agglutination of erythrocytes (i.e., sialic acid-dependent hemagglutination). In this context, the SabA adhesin was identified as the sialic acid-dependent hemagglutinin based on sialidase-sensitive hemagglutination, binding assays with sialylated glycoconjugates, and analysis of a series of isogenic sabA deletion mutants. The topographic presentation of binding sites for SabA on the erythrocyte membrane was mapped to gangliosides with extended core chains. However, receptor mapping revealed that the NeuAcalpha2-3Gal-disaccharide constitutes the minimal sialylated binding epitope required for SabA binding. Furthermore, clinical isolates demonstrated polymorphism in sialyl binding and complementation analysis of sabA mutants demonstrated that polymorphism in sialyl binding is an inherent property of the SabA protein itself. Gastric inflammation is associated with periodic changes in the composition of mucosal sialylation patterns. We suggest that dynamic adaptation in sialyl-binding properties during persistent infection specializes H. pylori both for individual variation in mucosal glycosylation and tropism for local areas of inflamed and/or dysplastic tissue.
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| 4. |
- Haas, Brian J., et al.
(författare)
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Genome sequence and analysis of the Irish potato famine pathogen Phytophthora infestans
- 2009
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 461:7262, s. 393-398
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Tidskriftsartikel (refereegranskat)abstract
- Phytophthora infestans is the most destructive pathogen of potato and a model organism for the oomycetes, a distinct lineage of fungus-like eukaryotes that are related to organisms such as brown algae and diatoms. As the agent of the Irish potato famine in the mid-nineteenth century, P. infestans has had a tremendous effect on human history, resulting in famine and population displacement(1). To this day, it affects world agriculture by causing the most destructive disease of potato, the fourth largest food crop and a critical alternative to the major cereal crops for feeding the world's population(1). Current annual worldwide potato crop losses due to late blight are conservatively estimated at $6.7 billion(2). Management of this devastating pathogen is challenged by its remarkable speed of adaptation to control strategies such as genetically resistant cultivars(3,4). Here we report the sequence of the P. infestans genome, which at similar to 240 megabases (Mb) is by far the largest and most complex genome sequenced so far in the chromalveolates. Its expansion results from a proliferation of repetitive DNA accounting for similar to 74% of the genome. Comparison with two other Phytophthora genomes showed rapid turnover and extensive expansion of specific families of secreted disease effector proteins, including many genes that are induced during infection or are predicted to have activities that alter host physiology. These fast-evolving effector genes are localized to highly dynamic and expanded regions of the P. infestans genome. This probably plays a crucial part in the rapid adaptability of the pathogen to host plants and underpins its evolutionary potential.
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| 5. |
- Li, Jing-Jing, et al.
(författare)
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Immobilized Triton X-100-assisted refolding of Green Fluorescent Protein-Tobacco Etch Virus protease fusion protein using β-cyclodextrin as the eluent
- 2009
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Ingår i: Process Biochemistry. - : Elsevier BV. - 1359-5113 .- 1873-3298. ; 44:3, s. 277-282
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Tidskriftsartikel (refereegranskat)abstract
- A new protein refolding technique based on the use of the non-charged detergent Triton X-100 immobilized to the cross-linked agarose gel Sepharose High Performance has been developed. The new solid phase was used in combination with soluble β-cyclodextrin (β-CD) to refold recombinant Green Fluorescent Protein fused to Tobacco Etch Virus protease (GFPTEVP) expressed as inclusion bodies in E. coli. Previous attempts to refold recombinant GFPTEVP by dilution had failed. In the new procedure a column packed with Triton X-100-coupled Sepharose High Performance was used to capture unfolded GFPTEVP followed by elution using an increasing β-CD concentration gradient. The yield of properly refolded GFPTEVP was 46% at a protein concentration of 380 μg/ml. In contrast, dilution refolding of GFPTEVP at 200 μg/ml refolding buffer resulted in only 4.7% of native protein.
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| 6. |
- Liu, Haibin, et al.
(författare)
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Asymmetric oxidation of sulfides with hydrogen peroxide catalyzed by a vanadium complex of a new chiral NOO-ligand
- 2009
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Ingår i: Catalysis communications. - : Elsevier BV. - 1566-7367 .- 1873-3905. ; 11:4, s. 294-297
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Tidskriftsartikel (refereegranskat)abstract
- A new chiral NOO-tridentate ligand (8R)-2-(2-hydroxyphenyl)-4-methyl-5,6,7.8-tetrahydro-quinolin-8-ol (1) bearing a rigid tetrahydroquinoline framework was prepared and applied in the vanadium-catalyzed asymmetric oxidation of aryl methyl sulfides with H2O2 as oxidant. Less toxic acetone was found to be the proper solvent for the enantioselective oxidation of sulfides. Under the optimal condition, the asymmetric oxidation of aryl methyl sulfides in acetone catalyzed by VO(acac)(2)/1 at 0 degrees C gives good to high yields (80-95%) of sulfoxides with enantioselectivity up to 77% ee.
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| 7. |
- Liu, Hui, et al.
(författare)
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Confinement effect on scattering states in a thin lead film: Field-induced resonance states in the high-bias regime of scanning tunneling microscopy
- 2007
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Ingår i: Physical Review B. ; 76:11
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Tidskriftsartikel (refereegranskat)abstract
- Field-induced resonance states in the high-bias regime of scanning tunneling microscopy are used to couple and probe the scattering states above the vacuum level in a thin lead film. The resonance energies show a bilayer oscillation as a function of film thickness. Theoretical modeling unveils that the oscillation results from the confinement of the highly excited scattering states by the quantum well, yielding a bilayer phase modulation at the boundaries where they are coherently coupled to the external states.
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| 8. |
- Liu, KRY, et al.
(författare)
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Activities of daily living performance in dementia
- 2007
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Ingår i: Acta Neurologica Scandinavica. - Oxford : Blackwell Publishing. - 0001-6314 .- 1600-0404. ; 116:2, s. 91-95
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To explore the activities of daily living ADL performance profile of community-living people with dementia and to investigate its relationship with dementia severity.Materials & Methods: ADL performance of 86 subjects were evaluated using Barthel Index (BI), Lawton and Brody's Instrumental Activities Daily Living (IADL) and Assessment of Motor and Process Skills (AMPS). Dementia severity was measured by Clinical Dementia Rating (CDR).Results: Subjects were able to perform most basic ADL (BI mean = 16.4) and some IADL (Lawton and Brody's IADL mean = 4.3). The AMPS process ability measure and the Lawton and Brody's IADL were significantly correlated with CDR (P < 0.01).Conclusions: Subjects with mild dementia were able to perform mostly all basic ADL and some IADL. The AMPS process ability measure and the Lawton and Brody's IADL could provide useful information on their ability to live independently in the community.
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| 9. |
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| 10. |
- Wang, Zhen, et al.
(författare)
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Azadithiolates cofactor of the iron-only hydrogenase and its PR3-monosubstituted derivatives : Synthesis, structure, electrochemistry and protonation
- 2007
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Ingår i: Journal of Organometallic Chemistry. - : Elsevier BV. - 0022-328X .- 1872-8561. ; 692:24, s. 5501-5507
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Tidskriftsartikel (refereegranskat)abstract
- The core structure (mu-SCH2)(2)NH[Fe-2(CO)(6)](5) of Fe-only hydrogenases active site model has been synthesized by the condensation of iron carbonyl sulfides, formaldehyde and silyl protected amine. Its monosubstituted complexes (mu-SCH2)(2)NH[Fe-2(CO)(5)PR3] (R = Ph (6), Me (7)) were accordingly prepared. The coordination configurations of 5 and 6 were characterized by X-ray crystallography. Protonation of complex 7 to form the N-protonated product occurs in an acetonitrile solution upon addition of triflic acid. The redox properties of these model complexes were studied by cyclic voltammetry.
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| 11. |
- Wang, Zhen, et al.
(författare)
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Pentacarbonyl-1 kappa C-2,2 kappa 3C-(diphenyl-phosphine-1kP)(mu-2-propyl-2-aza-propane-1,3-dithiolato-1 kappa S-2,S ' : 2 kappa S-2,S ')diiron(Fe-Fe)
- 2007
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Ingår i: Acta Crystallographica Section E. - : International Union of Crystallography (IUCr). - 1600-5368. ; 63, s. M1959-U1552
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Tidskriftsartikel (refereegranskat)abstract
- The title compound, [Fe-2(C5H11NS2)(C12H11P)(CO)(5)], has been prepared and characterized as a model compound of the iron hydrogenase active site through controlled CO ligand displacement of (mu-SCH2)(2)N(CH2CH2CH3)[Fe-2(CO)(6)] with diphenylphosphine. The central Fe2S2 structure is in a butterfly conformation, and each Fe atom displays pseudo-square-pyramidal geometry. The phosphine group occupies an apical position. The propyl group on the bridging N atom is in an equatorial position and takes a zigzag form. In the crystal packing, adjacent pairs of molecules are associated by S center dot center dot center dot S (3.625 angstrom) intermolecular nonbonded weak interactions.
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| 12. |
- Zhang, Qiang, et al.
(författare)
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Spatial and temporal variability of precipitation maxima during 1960-2005 in the Yangtze River basin and possible association with large-scale circulation
- 2008
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 353:3-4, s. 215-227
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated spatial and temporal patterns of trends of the precipitation maxima (defined as the annual./seasonal. maximum precipitation) in the Yangtze River basin for 1960-2005 using Mann-Kendall trend test, and explored association of changing patterns of the precipitation maxima with large-scale circulation using NCEP/NCAR reanalysis data. The research results indicate changes of precipitation maxima from relative stable patterns to the significant increasing/decreasing trend in the middle 1970s. With respect to annual variability, the rainy days are decreasing and precipitation intensity is increasing, and significant increasing trend of precipitation intensity was detected in the middle and lower Yangtze River basin. Number of rain days with daily precipitation exceeding 95th and 99th percentiles and related precipitation intensities are in increasing tendency in summer. Large-scale atmospheric circulation analysis indicates decreasing strength of East Asian summer monsoon during 1975-2005 as compared to that during 1961-1974 and increasing geopotential height in the north China, South China Sea and west Pacific regions, all of which combine to negatively impact the northward propagation of the vapor flux. This circulation pattern will be beneficial for the longer stay of the Meiyu front in the Yangtze River basin, leading to more precipitation in the middle and lower Yangtze River basin in summer months. The significant increasing summer precipitation intensity and changing frequency in the rain/no-rain days in the middle and lower Yangtze River basin have potential to result in higher occurrence probability of flood and drought hazards in the region.
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