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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. |
- Gao, Bin, et al.
(författare)
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Studies of bromine modified single-walled carbon nanotubes using photoelectron spectroscopy and density-functional theory
- 2006
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Ingår i: Radiation Physics and Chemistry. - : Elsevier BV. - 0969-806X .- 1879-0895. ; 75:11, s. 1939-1942
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Tidskriftsartikel (refereegranskat)abstract
- Many applications based on single-walled carbon nanotubes (SWNTs) require chemical modification of carbon nanotube to optimize the functionalities of the device. In this contribution we discuss the properties of SWNTs immersed in a hydrobromic acid (HBr) solution. Changes of atomic and electronic structures of bromine modified SWNTs were investigated using photoelectron spectroscopy (PES). Spectra of SWNTs before and after immersion in the HBr solution exhibit different features. To understand the mechanism of interaction between SWNTs and bromine, we performed density-functional theory calculations to reveal the structural changes, adsorption energy and chemical bonding information of SWNTs interacting with bromine. In addition, based on the Gelius model, from the molecular orbitals (MOs), we calculated ultraviolet photoelectron spectra (UPS) of SWNTs with and without functionalizing and compared them with the experiment. The present study is a first step in the understanding of the functionalization mechanism of carbon nanotubes.
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| 4. |
- WANG, Hai-feng, et al.
(författare)
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Study on Oasis Distribution Patterns in Dry In-land River Basins
- 2005
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Ingår i: Journal of Hydraulic Engineering. - 1943-7900. ; 36:12, s. 1457-1463
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Tidskriftsartikel (refereegranskat)abstract
- Based on a comparative analysis approach of oasis distributed in arid area of Northwest China, this paper brings up and describes two kinds of oasis distribution pattern: mid-lower reach pattern and middle reach pattern. It is found that the water availability per capita of mid-lower reach pattern is higher than that of middle reach pattern, while the water resources exploitation percentage of mid-lower reach pattern is lower than that of middle reach pattern. The GDP per capita and the urbanization percentage of middle lower reach pattern is lower than those of middle reach pattern in general. The general output per unit water resources of mid-lower reach pattern is lower than that of middle reach pattern as a whole. Through comparing and studying the characteristics of the representative distribution pattern, it is pointed out that the key factor that leads to different oasis pattern is the differences of water resources and social economy development. Under the circumstance of population fast growing, water availability per capita will decrease accordingly. To maintain the oasis stability in line with economic development, improved production efficiency of water resources and balanced social-economic pattern are strongly required.
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| 5. |
- Yu, Ling-Zhu, et al.
(författare)
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MEK1/2 regulates microtubule organization, spindle pole tethering and asymmetric division during mouse oocyte meiotic maturation.
- 2007
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Ingår i: Cell cycle (Georgetown, Tex.). - 1551-4005. ; 6:3, s. 330-8
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that MAPK plays pivotal roles in oocyte maturation, but the function of MEK (MAPK kinase) remains unknown. We have studied the expression, subcellular localization and functional roles of MEK during meiotic maturation of mouse oocytes. Firstly, we found that MEK1/2 phoshorylation (p-MEK1/2, indicative of MEK activation) was low in GV (germinal vesicle) stage, increased 2h after GVBD (germinal vesicle breakdown), and reached the maximum at metaphase II. Secondly, we found that P-MEK1/2 was restricted in the GV prior to GVBD. In prometaphase I and metaphase I, P-MEK1/2 was mainly associated with the spindle, especially with the spindle poles. At anaphase I and telophase I, p-MEK1/2 became diffusely distributed in the region between the separating chromosomes, and then became associated with the midbody. The association of p-MEK1/2 with spindle poles was further confirmed by its colocalization with the centrosomal proteins, gamma-tubulin and NuMA. Thirdly, we have investigated the possible functional role of MEK1/2 activation by intravenous administration and intrabursal injection of a specific MEK inhibitor, U0126, and by microinjection of MEK siRNA into oocytes. All these manipulations cause disorganized spindle poles and spindle structure, misaligned chromosomes and larger than normal polar bodies. Our results suggest that MEK1/2 may function as a centrosomal protein and may have roles in microtubule organization, spindle pole tethering and asymmetric division during mouse oocyte maturation.
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| 6. |
- Yuesheng, Ning, et al.
(författare)
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Single molecule's conductance depending on its orientation
- 2009
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 113:1, s. 26-30
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Tidskriftsartikel (refereegranskat)abstract
- Single molecules of 1,1,2,3,4,5-hexaphenylsilole adsorbed on Cu(111) have been investigated using low-temperature scanning tunneling microscopy, scanning tunneling spectroscopy, and quantum chemistry calculations. Two adsorption states have been identified, showing distinctive tunneling conductance. The molecules can switch their states under tip influence. Theoretical calculations indicate that the two states are associated with molecules adsorbed at two 90°-rotated orientations, and the tunneling conductance is attributed to molecular orbitals that spatially bridge tip-to-substrate gap. Our findings demonstrate a decisive dependence of single-molecule conductance on the molecular orientation with respect to electrodes.
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| 7. |
- Zhong, H. M., et al.
(författare)
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A first principles study on optical transparency mechanism in Dy doped alpha-SiAlON ceramics
- 2009
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 106:9
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Tidskriftsartikel (refereegranskat)abstract
- Dy doped alpha-SiAlON ceramics prepared by the hot-pressing method show a high optical transmittance value, >70%, in the infrared region of 1.5-4.5 mu m. First principles calculations have been carried out to reveal the underlying transparency mechanism. It is found that the valence shell of doped Dy atoms interacts strongly with the doping states of alpha-SiAlON, resulting in the increase in the optical gap from 0.4 to 1.1 eV, which suppresses the photoabsorption in the wavelength region longer than 1.0 mu m and leads to the good transparency property. The calculated optical transmission spectra are in good agreement with the corresponding experiments.
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| 8. |
- Zhong, Jun, et al.
(författare)
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Bio-nano interaction of proteins adsorbed on single-walled carbon nanotubes
- 2009
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 47:4, s. 967-973
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Tidskriftsartikel (refereegranskat)abstract
- We applied X-ray absorption near edge structure (XANES) spectroscopy to investigate the adsorption of proteins onto single-walled carbon nanotubes (SWCNTs). Specific XANES spectral features such as peptide C=O bonds in proteins were recognized and found to be affected by the corresponding aromatic structure of SWCNTs. Experimental data combined with first-principle calculation of the investigated nano-complex allow the understanding of adsorption mechanism and reveal that an interface interaction occurs leading to precise structural distortions of proteins. The study also demonstrates that XANES is a powerful tool to characterize structural details of proteins at the interface of complex systems.
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