| 1. |
- Birney, Ewan, et al.
(författare)
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Identification and analysis of functional elements in 1% of the human genome by the ENCODE pilot project
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 447:7146, s. 799-816
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Tidskriftsartikel (refereegranskat)abstract
- We report the generation and analysis of functional data from multiple, diverse experiments performed on a targeted 1% of the human genome as part of the pilot phase of the ENCODE Project. These data have been further integrated and augmented by a number of evolutionary and computational analyses. Together, our results advance the collective knowledge about human genome function in several major areas. First, our studies provide convincing evidence that the genome is pervasively transcribed, such that the majority of its bases can be found in primary transcripts, including non-protein-coding transcripts, and those that extensively overlap one another. Second, systematic examination of transcriptional regulation has yielded new understanding about transcription start sites, including their relationship to specific regulatory sequences and features of chromatin accessibility and histone modification. Third, a more sophisticated view of chromatin structure has emerged, including its inter-relationship with DNA replication and transcriptional regulation. Finally, integration of these new sources of information, in particular with respect to mammalian evolution based on inter- and intra-species sequence comparisons, has yielded new mechanistic and evolutionary insights concerning the functional landscape of the human genome. Together, these studies are defining a path for pursuit of a more comprehensive characterization of human genome function.
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| 2. |
- Cao, Hui, et al.
(författare)
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Identification of switching mechanism in molecular junctions by inelastic electron tunneling spectroscopy
- 2008
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:29, s. 11018-11022
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Tidskriftsartikel (refereegranskat)abstract
- We present first-principles studies on electron transport properties of Pd-dithiolated oligoaniline-Pd molecular junctions. It is to demonstrate the possibility of using inelastic electron tunneling spectroscopy (IETS) to identify the switching mechanism in the molecular junction. Calculations have successfully reproduced the experimentally observed conductance switching behavior and the corresponding inelastic electron tunneling spectra. It is shown that the conductance switching is induced by conformation changes of the intercalated dithiolated oligoaniline in the junctions rather than oxidation/reduction as proposed earlier. Among three possible isomers, the low and high conductance states are related to two symmetrical structures. The possible involvement of asymmetric structure is discussed. It is revealed that chemical bonds between the terminal S atom and Pd electrodes are quite weak with relatively long bond distances.
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| 3. |
- Cao, Hui, et al.
(författare)
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Temperature-dependent statistical behavior of single molecular conductance in aqueous solution
- 2008
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 130:21, s. 6674-
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Tidskriftsartikel (refereegranskat)abstract
- We have combined molecular dynamics simulations with first principles calculations to study electron 4 transport in a single molecule of perylene tetracarboxylic diimide (PTCDI) sandwiched between two gold electrodes with an aqueous electrolyte. This combination has for the first time allowed one to reveal statistical behavior of molecular conductance in solution at different temperatures and to produce conductance histograms that can be directly compared with experiments. Our calculations show that experimentally observed temperature-dependent conductance ran be attributed to the thermal effect on the hydrogen bonding network around the molecule and can be described by the radial distribution of water molecules surrounding the oxygen atom in the PTCDI molecule.
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| 4. |
- Gao, Bin, et al.
(författare)
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An efficient first-principle approach for electronic structures calculations of nanomaterials
- 2008
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Ingår i: Journal of Computational Chemistry. - : Wiley. - 0192-8651 .- 1096-987X. ; 29:3, s. 434-444
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Tidskriftsartikel (refereegranskat)abstract
- An efficient parallel implementation has been realized for a recently proposed central insertion scheme (Jiang, Liu, Lu, Luo. J Chem Phys 2006,124,214711; J Chem Phys 2006,125, 149902) that allows to calculate electronic structures of nanomaterials at various density functional theory levels. It has adopted the sparse-matrix format for Fock/Kohn-Sham and overlap matrices, as well as a combination of implicitly restarted Arnoldi methods (IRAM) and spectral transformation for computing selected eigenvalues/eigenvectors. A systematic error analysis and control for the proposed method has been provided based on a strict mathematical basis. The efficiency and applicability of the new implementation have been demonstrated by calculations of electronic structures of two different nanomaterials consisting of one hundred thousand electrons.
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| 5. |
- Gao, Bin, et al.
(författare)
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Energy gaps, electronic structures, and x-ray spectroscopies of finite semiconductor single-walled carbon nanotubes
- 2008
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 128:8, s. 084707-1-084707-8
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Tidskriftsartikel (refereegranskat)abstract
- We report hybrid density functional theory calculations for electronic structures of hydrogen-terminated finite single-walled carbon nanotubes (6,5) and (8,3) up to 100 nm in length. Gap states that are mainly arisen from the hydrogen-terminated edges have been found in (8,3) tubes, but their contributions to the density of states become invisible when the tube is longer than 10 nm. The electronic structures of (6,5) and (8,3) tubes are found to be converged around 20 nm. The calculated band-gap energies of 100 nm long nanotubes are in good agreement with experimental results. The valence band structures of (6,5), (8,3), as well as (5,5) tubes are also investigated by means of ultraviolet photoelectron spectra (UPS), x-ray emission spectroscopy (XES), and the resonant inelastic x-ray scattering (RIXS) spectra theoretically. The UPS, XES and RIXS spectra become converged already at 10 nm. The length-dependent oscillation behavior is found in the RIXS spectra of (5,5) tubes, indicating that the RIXS spectra may be used to determine the size and length of metallic nanotubes. Furthermore, the chiral dependence observed in the simulated RIXS spectra suggests that RIXS spectra could be a useful technique for the determination of chirality of carbon nanotubes.
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| 6. |
- Gao, Bin, et al.
(författare)
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Simulation of electronic structure of nanomaterials by central insertion scheme
- 2009
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Ingår i: FRONTIERS OF PHYSICS IN CHINA. - : Springer Science and Business Media LLC. - 1673-3487 .- 1673-3606. ; 4:3, s. 307-314
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Tidskriftsartikel (refereegranskat)abstract
- An effective central insertion scheme (CIS) that allows to study the electronic structure of nanomaterials at the first principles level is introduced. Taking advantage of advanced numerical methods, such as the implicitly restarted Arnoldi method (IRAM) and spectral transformation, together with efficient parallelization technique, this scheme can provide accurate electronic structures and properties of one-, two-, and three-dimensional nanomaterials with only a fraction of computational time required for conventional quantum chemical calculations. Electronic structures of several nanostructures, such as single-walled carbon nanotubes of sub-100 nm in length, silicon nanoclusters of sub-6.5 nm in diameter and metal doped silicon clusters, calculated at hybrid density functional level are presented.
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| 7. |
- He, Lu-Jun, et al.
(författare)
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Genetic polymorphisms of N-acetyltransferase 2 and colorectal cancer risk.
- 2005
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Ingår i: World Journal of Gastroenterology. - 1007-9327 .- 2219-2840. ; 11:27, s. 4268-4271
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To identify the distribution of N-acetyltrasferase 2(NAT2) polymorphism in Hebei Han Chinese and the effects of the polymorphism on the development of colorectal cancer. METHODS: We performed a hospital-based case-control study of 237 healthy individuals and 83 colorectal cancer patients of Hebei Han Chinese. DNA was extracted from peripheral blood and cancer tissues. The genotypes of the polymorphisms were assessed by PCR-restriction fragment length polymorphism (RFLP). RESULTS: There were four NAT2 alleles of WT, M1, M2, and M3 both in the healthy subjects and in the patients, and 10 genotypes of WT/WT, WT/M1, WT/M2, WT/M3, M1/M1, M1/M2, M1/M3, M2/M2, M2/M3, M3/M3. M2 allele was present in 15.61% of healthy subjects and 29.52% of patients (chi(2) = 15.31, P<0.0001), and M3 allele was present in 30.59% of healthy subjects and 16.87% of patients (chi(2) = 25.33, P<0.0001). There were more WT/M2 (chi(2) = 34.42, P<0.0001, odd ratio = 4.99, 95%CI = 2.27-9.38) and less WT/M3 (chi(2) = 3.80, P = 0.03) in the patients than in the healthy subjects. In 70.3% of the patients, there was a difference in NAT2 genotype between their tumors and blood cells. Patients had more WT/M2 (chi(2) = 5.11, P = 0.02) and less M2/M3 (chi(2) = 4.27, P = 0.039) in their blood cells than in the tumors. Furthermore, 53.8% (7/13) of M2/M3 in tumors were from WT/M2 of blood cells. CONCLUSION: There is a possible relationship between the NAT2 polymorphisms and colorectal cancer in Hebei Han Chinese. The genotype WT/M2 may be a risk factor for colorectal cancer.
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| 8. |
- Hu, W., et al.
(författare)
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Electron transport in self-assembled polymer molecular junctions
- 2006
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 96:2, s. 027801-
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Tidskriftsartikel (refereegranskat)abstract
- A molecular junction of a poly(p-phenyleneethynylene)s derivative with thioacetate end groups (TA-PPE) was fabricated by self-assembling. Nanogap electrodes made by electroplating technique was used to couple thiol end groups of TA-PPE molecules. Room temperature current-voltage characteristics of the molecular junction exhibited highly periodic, repeatable, and identical stepwise features. First-principles calculations suggest that one possibility for the equidistant step is due to the opening of different conducting channels that corresponds to the unoccupied molecular orbitals of the polymer in the junction. It is interesting to see that an 18 nm long polymer is of quantized electronic structures and behaves like a quantum transport device.
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| 9. |
- Jiang, Jun, et al.
(författare)
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A generalized quantum chemical approach for elastic and inelastic electron transports in molecular electronics devices
- 2006
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 124:3, s. 034708-1-034708-10
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Tidskriftsartikel (refereegranskat)abstract
- A generalized quantum chemical approach for electron transport in molecular devices is developed. It allows one to treat devices where the metal electrodes and the molecule are either chemically or physically bonded on equal footing. An extension to include the vibration motions of the molecule has also been implemented which has produced the inelastic electron-tunneling spectroscopy of molecular electronics devices with unprecedented accuracy. Important information about the structure of the molecule and of metal-molecule contacts that are not accessible in the experiment are revealed. The calculated current-voltage (I-V) characteristics of different molecular devices, including benzene-1,4-dithiolate, octanemonothiolate [H(CH2)(8)S], and octanedithiolate [S(CH2)(8)S] bonded to gold electrodes, are in very good agreement with experimental measurements.
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| 10. |
- Jiang, Jun
(författare)
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A generalized quantum chemical approach for nano- and bio-electronics
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A generalized quantum chemical approach for electron transport in molecular devices is developed. It allows to treat the devices where the metal electrodes and the molecule are either chemically or physically bonded on equal footing. Effects of molecular length and hydrogen bonding on the current-voltage (I-V) characteristics of molecular devices are discussed. An extension to include the vibration motions of the molecule has been derived and implemented. It provides the inelastic electron tunneling spectroscopy (IETS) of molecular devices with unprecedented accuracy, and reveals important information about the molecular structures that are not accessible in the experiment. The IETS is shown to be a powerful characterization tool for molecular devices. An effective elongation method has been developed to study the electron transport in nanoand bio-electronic devices at hybrid density functional theory level. It enables to study electronic structures and transportation properties of a 40 nm long self-assembled conjugated polymer junction, a 21 nm long single-walled carbon nanotubes (SWCNT), and a 60 basepairs DNA molecule. It is the first time that systems consisting of more than 10,000 electrons have been described at such a sophisticated level. The calculations have shown that the electron transport in sub-22 nm long SWCNT and short DNA molecules is dominated by the coherent scattering through the delocalized unoccupied states. The derived length dependence of coherent electron transport in these nanostructured systems will be useful for the future experiments. Moreover, some unexpected behaviors of these devices have been discovered.
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| 11. |
- Jiang, Jun, 1978-
(författare)
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A Quantum Chemical View of Molecular and Nano-Electronics
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation presents a generalized quantum chemical approach for electron transport in molecular electronic devices based on Green's function scattering theory. It allows to describe both elastic and inelastic electron transport processes at first principles levels of theory, and to treat devices with metal electrodes either chemically or physically bonded to the molecules on equal footing. Special attention has been paid to understand the molecular length dependence of current-voltage characteristics of molecular junctions. Effects of external electric fields have been taken into account non-perturbatively, allowing to treat electrochemical gate-controlled single molecular field effect transistors for the first time. Inelastic electron tunneling spectroscopy of molecular junctions has been simulated by including electron-vibration couplings. The calculated spectra are often in excellent agreement with experiment, revealing detailed structure information about the molecule and the bonding between molecule and metal electrodes that are not accessible in the experiment. An effective central insertion scheme (CIS) has been introduced to study electronic structures of nanomaterials at first principles levels. It takes advantage of the partial periodicity of a system and uses the fact that long range interaction in a big system dies out quickly. CIS method can save significant computational time without loss of accuracy and has been successfully applied to calculate electronic structures of one- , two- , and three-dimensional nanomaterials, such as sub-116 nm long conjugated polymers, sub-200nm long single-walled carbon nanotubes, sub-60 base pairs DNA segments, nanodiamondoids of sub-7.3nm in diameter and Si-nanoparticles of sub-6.5nm in diameter at the hybrid density functional theory level. The largest system under investigation consists of 100,000 electrons. The formation of energy bands and quantum confinement effects in these nanostructures have been revealed. Electron transport properties of polymers, SWCNTs and DNA have also been calculated.
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| 12. |
- Jiang, Jun, et al.
(författare)
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Ab initio study of energy band structures of GaAs nanoclusters
- 2009
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 94:9
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Tidskriftsartikel (refereegranskat)abstract
- Electronic states and optical transitions of hydrogen terminated GaAs nanoclusters up to 16.9 nm in diameter were studied using a large-scale quantum chemistry approach called central insertion scheme by which the quantum confinement effect is shown to quantitatively agree with experimental results. The ab initio study further reveals that the effective mass of the conduction-band electron (valence-band hole) in the GaAs nanocluster is larger (smaller) than the bulk material value.
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| 13. |
- Jiang, Jun, et al.
(författare)
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An elongation method for first principle simulations of electronic structures and electron transport properties of finite nanostructures
- 2006
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 124:21, s. 214711-
-
Tidskriftsartikel (refereegranskat)abstract
- An effective elongation method has been developed to study electronic structures and electron transport properties of nanoelectronic and bioelectronic devices at a hybrid density functional theory level. It enables to treat finite nanostructures consisting of as many as 28 000 electrons and has been successfully applied to sub-120-nm-long conjugated polymers, sub-60-nm-long single-walled carbon nanotubes, and 30 base-pair DNA molecules. The calculated current-voltage characteristics of different systems are found to be in good agreement with the experiments. Some unexpected behaviors of these nanosized devices have been discovered.
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| 14. |
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| 15. |
- Jiang, Jingting, et al.
(författare)
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Clinical Evaluation of Serum Alpha-Fetoprotein-IgM Immune Complexes on the Diagnosis of Primary Hepatocellular Carcinoma
- 2009
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Ingår i: Journal of Clinical Laboratory Analysis. - : Wiley. - 1098-2825 .- 0887-8013. ; 23:4, s. 213-218
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated clinical significance of serum alpha-fetoprotein (AFP)-IgM immune complexes, in comparison with free AFP, on the diagnosis of primary hepatocellular carcinoma (HCC). Serum levels of AFP-IgM immune complexes and free AFP were determined by the ELISA method and electrochemiluminescence, respectively, in 103 healthy controls, 74 patients suffering from primary HCC, 27 patients suffering from liver cirrhosis, and 63 patients suffering from chronic hepatitis. The best cut-off value of AFP-IgM and free AFP for diagnosis of primary HCC were 300 AU/mL and 10 mu g/L respectively, according to the area under the curve (AUC) in this study. The sensitivity of AFP-IgM and free AFP were 64.9 and 79.7%, and the specificity were 75.6 and 80.3%, respectively, when all cases of primary HCC were analyzed, and the AUC of free AFP was larger than that of AFP-IgM (0.85 vs. 0.72, Z = 3.21). However, in case of primary HCC at early stages (stages I and II) were analyzed, the AUC of AFP-IgM was larger than that of free AFP (0.91 vs. 0.82, Z = 1.73), which demonstrated that the sensitivity of AFP-IgM and free AFP were 94.4 and 72.2%, and the specificity were 81.9 and 79.9%, respectively. When both AFP-IgM and free AFP were positive, the specificity of diagnosis of primary HCC was 89.1%, and the efficacy was 79.0%. It is concluded that either sensitivity or specificity of serum level of AFP-IgM immune complexes was higher than that of free AFP in the diagnosis of primary HCC at early stages. As there was false positive AFP-IgM existed in the patients suffering from cirrhosis and chronic hepatitis, the combination of free AFP and AFP-IgM could significantly increase specificity and decrease false negative and/or false positive in the primary HCC at early stages. J. Clin. Lab. Anal. 23:213-218, 2009. (C) 2009 Wiley-Liss, Inc.
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| 16. |
- Jiang, Jun, et al.
(författare)
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First-principles simulations of inelastic electron tunneling spectroscopy of molecular electronic devices
- 2005
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 5:8, s. 1551-1555
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Tidskriftsartikel (refereegranskat)abstract
- Inelastic electron tunneling spectroscopy (IETS) is a powerful experimental tool for studying the molecular and metal contact geometries in molecular electronic devices. A first-principles computational method based on the hybrid density functional theory is developed to simulate the IETS of realistic molecular electronic devices. The calculated spectra of a real device with an octanedithiolate embedded between two gold contacts are in excellent agreement with recent experimental results. Strong temperature dependence of the experimental IETS spectra is also reproduced. It is shown that the IETS is extremely sensitive to the intramolecular conformation and the molecule-metal contact geometry changes. With the help of theoretical calculations, it has finally become possible to fully understand and assign the complicated experimental IETS and, more importantly, provide the structural information of the molecular electronic devices.
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| 17. |
- Jiang, Jun, et al.
(författare)
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Molecular modeling of inelastic electron transport in molecular junctions
- 2008
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 20:37
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Tidskriftsartikel (refereegranskat)abstract
- A quantum chemical approach for the modeling of inelastic electron tunneling spectroscopy of molecular junctions based on scattering theory is presented. Within a harmonic approximation, the proposed method allows us to calculate the electron-vibration coupling strength analytically, which makes it applicable to many different systems. The calculated inelastic electron transport spectra are often in very good agreement with their experimental counterparts, allowing the revelation of detailed information about molecular conformations inside the junction, molecule-metal contact structures, and intermolecular interaction that is largely inaccessible experimentally.
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| 18. |
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| 19. |
- Kula, Mathias, et al.
(författare)
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A molecular view on electron transport in molecular electronic devices
- 2008
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Ingår i: Journal of Computational and Theoretical Nanoscience. - : American Scientific Publishers. - 1546-1955 .- 1546-1963. ; 5:4, s. 401-421
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Forskningsöversikt (refereegranskat)abstract
- A review of a typical Green's function based scattering theory model for molecular electronics is presented. It focuses on the description of central part of the molecular devices, namely the molecule-metal junction. It allows to combine with various advanced density functional theory approaches to model elastic and inelastic electron transport properties of a variety of single molecular devices. It can treat the molecular junctions with either chemically or physically bonded molecular interfaces on equal footing and is fairly insensitive to the choice of functionals and basis sets. The method can capture the fundamental physics behind the electron transport properties and largely reproduce many experimental results for nonlinear current-voltage characteristics, inelastic electron tunneling spectroscopy, and single molecule field-effect transistors.
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| 20. |
- Kula, Mathias, et al.
(författare)
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Effects of Hydrogen Bonding on Current−Voltage Characteristics of Molecular Junctions
- 2006
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 125:19, s. 194703-1-194703-7
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Tidskriftsartikel (refereegranskat)abstract
- We present a first-principles study of hydrogen bonding effect on current-voltage characteristics of molecular junctions. Three model charge-transfer molecules, 2'-amino-4,4'-di(ethynylphenyl)-1-benzenethiolate (DEPBT-D), 4,4'-di(ethynylphenyl)-2'-nitro-1-benzenethiolate (DEPBT-A), and 2'-amino-4,4'-di(ethynylphenyl)-5'-nitro-1-benzenethiolate (DEPBT-DA), have been examined and compared with the corresponding hydrogen bonded complexes formed with different water molecules. Large differences in current-voltage characteristics are observed for DEPBT-D and DEPBT-A molecules with or without hydrogen bonded waters, while relatively small differences are found for DEPBT-DA. It is predicted that the presence of water clusters can drastically reduce the conductivities of the charge-transfer molecules. The underlying microscopic mechanism has been discussed.
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| 21. |
- Kula, Mathias, et al.
(författare)
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Probing molecule-metal bonding in molecular junctions by inelastic electron tunneling spectroscopy
- 2006
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 6:8, s. 1693-1698
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Tidskriftsartikel (refereegranskat)abstract
- We present first-principles calculations for the inelastic electron tunneling spectra ( IETS) of three molecules, 1-undecane thiol (C11), alpha, omega-bis(thioacetyl)oligophenylenethynylene (OPE), and alpha,omega-bis(thioacetyl) oligophenylenevinylene (OPV), sandwiched between two gold electrodes. We have demonstrated that IETS is very sensitive to the bonding between the molecule and electrodes. In comparison with experiment of Kushmerick et al. (Nano Lett. 2004, 4, 639), it has been concluded that the C11 forms a strong chemical bond, while the bonding of the OPE and OPV systems are slightly weaker. All experimental spectral features have been correctly assigned.
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| 22. |
- Li, Xin, et al.
(författare)
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Study on enhancement of fluorescence with gold nanorods
- 2008
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Ingår i: Asia Optical Fiber Communication and Optoelectronic Exposition and Conference 2008. - : Optical Society of America. - 9781557528636
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Konferensbidrag (refereegranskat)abstract
- Enhancement of fluorescence of streptavidin conjugated with gold nanorods (GNRs) was observed. The impact of GNRs with different surface plasmon resonance bands and different concentrations to the efficiency of the fluorescence enhancement was studied.
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| 23. |
- Richards, Stephen, et al.
(författare)
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The genome of the model beetle and pest Tribolium castaneum.
- 2008
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Ingår i: Nature. - 1476-4687. ; 452:7190, s. 949-55
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Tidskriftsartikel (refereegranskat)abstract
- Tribolium castaneum is a representative of earth’s most numerous eukaryotic order, a powerful model organism for the study of generalized insect development, and also an important pest of stored agricultural products. We describe its genome sequence here. This omnivorous beetle has evolved an ability to interact with a diverse chemical environment as evidenced by large expansions in odorant and gustatory receptors, as well as p450 and other detoxification enzymes. Developmental patterns in Tribolium are more representative of other arthropods than those found in Drosophila, a fact represented in gene content and function. For one, Tribolium has retained more ancestral genes involved in cell-cell communication than Drosophila, and some are expressed in the growth zone crucial for axial elongation in short germ development. Systemic RNAi in T. castaneum appears to use mechanisms distinct from those found in C. elegans, but nevertheless offers similar power for the elucidation of gene function and identification of targets for selective insect control.
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| 24. |
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| 25. |
- Su, Wenyong, et al.
(författare)
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First-principles study of electrochemical gate-controlled conductance in molecular junctions
- 2006
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 6:9, s. 2091-2094
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Tidskriftsartikel (refereegranskat)abstract
- A first-principles computational method is developed to study the electrochemical gate-controlled conductance in molecular junctions. It has been applied to a single molecular field-effect transistor made by a perylene tetracaboxylic diimide molecule connected to gold electrodes and has successfully reproduced the experimentally observed huge gate voltage effect on the current. It is found that such a significant gain is a result of the large polarization of the molecule induced by the huge local electrical field generated by the electrochemical gate. The resonant electron tunneling through unoccupied molecular orbitals is shown to be the dominant transport process.
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| 26. |
- Su, Wenyong, et al.
(författare)
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Quantum chemical study of coherent electron transport in oligophenylene molecular junctions of different lengths
- 2005
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 412:4-6, s. 406-410
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Tidskriftsartikel (refereegranskat)abstract
- The coherent electron transportation properties of the gold-oligophenylene-gold junctions of different lengths have been studied by means of a generalized quantum chemical approach. The experimentally measured length dependence of current flow in the junctions has been well reproduced by the hybrid density functional theory calculations. It is found that the current-voltage characteristics of the junctions depend strongly on the metal-molecule bonding distances. With the help of the calculations, the possible gold-molecule bonding distances in the experimental devices are identified.
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| 27. |
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| 28. |
- Tian, Yu-peng, et al.
(författare)
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Synthesis, crystal structure and NLO properties of a novel ruthenium(II) complex with unusual coordination mode
- 2005
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Ingår i: Transition metal chemistry (Weinheim). - : Kluwer Academic Publishers. - 0340-4285 .- 1572-901X. ; 30:7, s. 778-785
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Tidskriftsartikel (refereegranskat)abstract
- A new Schiff base 4-[N-hydroxyethyl-N-(methyl)amino]benzaldehyde S-methyl dithiocarbazate (HL, where H is a dissociable proton) and the ruthenium complex [Ru(bpy)2L]PF6 (bpy = 2,2′-bipyridine) have been synthesized. The structural determinations of the ligand and its ruthenium complex, by X-ray crystallography, show that the ligand is coordinated as a monoanionic bidentate N, S-donor, forming a four-member chelate ring with a bite angle of 65.91°. The complex shows intense MLCT transitions in the visible region. Fluorescent and electrochemical properties have been also studied. The complex in DMF solution exhibited a strong two-photon absorption (t.p.a.) at 532 nm nanosecond laser pulses. The t.p.a. coefficient β, t.p.a. cross-section σ and the third-order optical nonlinearity χ(3) of the complex and the ligand have been determined by the Z-scan technique.
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| 29. |
- 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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| 30. |
- Zhang, Xiaoying, et al.
(författare)
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IL-6 Regulates MMP-10 Expression via JAK2/STAT3 Signaling Pathway in a Human Lung Adenocarcinoma Cell Line
- 2009
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Ingår i: Anticancer research. - 1791-7530. ; 29:11, s. 4497-4501
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Tidskriftsartikel (refereegranskat)abstract
- We previously reported that matrix metalloproteinase (MMP)-10 mRNA levels were significantly lower in tumor tissues than in adjacent normal tissues in human non-small cell lung cancer (NSCLC), whereas protein levels of MMP-10 were higher in the tumor tissues than the adjacent tissues. The mechanism of this divergence is still unknown. In the present stud), the role of Janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT3) on interleukin (IL)-6 mediated regulation of MMP-10 expression was investigated in a human lung adenocarcinoma cell line (A549 cells) and the molecular regulatory mechanism of MMP-10 expression was explored. A549 cells were stimulated by different concentrations of IL-6 with or without AG490, a specific JAK2 inhibitor. It was demonstrated that IL-6 moderately reduced the MMP-10 mRNA levels, whereas it significantly enhanced the MMP-10 protein mass in the A549 cells. This phenomenon mimicked the divergence of mRNA level and protein mass of MMP-10 in human NSCLC. Moreover, the present study indicated that IL-6 regulation of MMP-10 expression was via the JAK2/STAT3 pathway. STAT3 mRNA levels were significantly increased when the cells were treated with IL-6, whereas when AG490 (50 mu M) was added to the cell cultures, IL-6-induced increase of STAT3 mRNA levels was abolished. Meanwhile, AG490 blocked the IL-6-induced inhibition of MMP-10 mRNA as well as blocking the IL-6-induced increase of MMP-10 protein mass in the A549 cells. Neither IL-6 nor AG490 influenced JAK2 mRNA levels in the A549 cell cultures. It is concluded that the JAK2/STAT3 pathway is involved in the IL-6-mediated regulation of MMP-10, and IL-6 can moderately reduce MMP-10 mRNA levels and strongly increase MMP-10 protein mass in human lung adenocarcinoma A549 cells. Contrasting effects of IL-6 on MMP-10 mRNA level and protein concentration in A549 cells may partially explain the divergence of MMP-10 mRNA level and protein mass in human NSCLC.
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| 32. |
- Zhao, Zeng-Ren, et al.
(författare)
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Particularly interesting new cysteine-histidine rich protein expression in colorectal adenocarcinomas
- 2006
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Ingår i: World Journal of Gastroenterology. - 1007-9327 .- 2219-2840. ; 12:2, s. 298-301
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To study the relationship between particularly interesting new cysteine-histidine rich protein (PINCH) expression and clinicopathological factors in Chinese colorectal cancer patients. Methods: The expression of PINCH was examined by immumohistochemistry in 141 samples of primary colorectal adenocarcinoma and 92 normal samples of colorectal mucosa. Eighty of the cases had both primary tumour and normal mucosa from the same patients. Results: PINCH was expressed in the stroma of normal mucosa and tumours. PINCH expression in tumourassociated stroma was increased compared to normal mucosa in both unmatched cases (n = 141, X2 = 85.79, df = 3, P<0.0001) and matched cases (n = 80, X2 = 45.86, df = 3, P<0.0001). Among 135 tumours with visible invasive margin, 86 (64%) showed stronger PINCH expression at the invasive margin than in the intratumoural stroma. The frequency of PINCH strong expression in mucinous and signet-ring cell carcinomas was higher (52%) compared to non-mucinous carcinomas (29%, X2= 5.13, P= 0.02). We did not find that PINCH expression was related to patient's gender, age, tumour location, tumour size, gross status, histological type, differentiation, invasion depth, lymph node status and Dukes' stage (P>0.05). Conclusion: The expression of PINCH was upregulated in colorectal cancers, and especially at the margin of tumours, and further was related to mucinous and signet-ring cell carcinomas. The results suggest that expression of PINCH may be involved in the tumourigenesis and aggressiveness of colorectal cancers. © 2006 The WJG Press. All rights reserved.
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| 33. |
- 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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