| 1. |
- Feng, Chungang, et al.
(author)
-
A cis-Regulatory Mutation of PDSS2 Causes Silky-Feather in Chickens
- 2014
-
In: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 10:8, s. e1004576-
-
Journal article (peer-reviewed)abstract
- Silky-feather has been selected and fixed in some breeds due to its unique appearance. This phenotype is caused by a single recessive gene (hookless, h). Here we map the silky-feather locus to chromosome 3 by linkage analysis and subsequently fine-map it to an 18.9 kb interval using the identical by descent (IBD) method. Further analysis reveals that a C to G transversion located upstream of the prenyl (decaprenyl) diphosphate synthase, subunit 2 (PDSS2) gene is causing silky-feather. All silky-feather birds are homozygous for the G allele. The silky-feather mutation significantly decreases the expression of PDSS2 during feather development in vivo. Consistent with the regulatory effect, the C to G transversion is shown to remarkably reduce PDSS2 promoter activity in vitro. We report a new example of feather structure variation associated with a spontaneous mutation and provide new insight into the PDSS2 function.
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| 2. |
- Weinstein, John N., et al.
(author)
-
The cancer genome atlas pan-cancer analysis project
- 2013
-
In: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 45:10, s. 1113-1120
-
Research review (peer-reviewed)abstract
- The Cancer Genome Atlas (TCGA) Research Network has profiled and analyzed large numbers of human tumors to discover molecular aberrations at the DNA, RNA, protein and epigenetic levels. The resulting rich data provide a major opportunity to develop an integrated picture of commonalities, differences and emergent themes across tumor lineages. The Pan-Cancer initiative compares the first 12 tumor types profiled by TCGA. Analysis of the molecular aberrations and their functional roles across tumor types will teach us how to extend therapies effective in one cancer type to others with a similar genomic profile. © 2013 Nature America, Inc. All rights reserved.
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| 3. |
- Li, Fei, et al.
(author)
-
A quantum search based signal detection for MIMO-OFDM systems
- 2011
-
In: 18th International Conference on Telecommunications, ICT 2011. - : IEEE. - 9781457700248 - 9781457700255 ; , s. 276-281
-
Conference paper (peer-reviewed)abstract
- Multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) is considered as candidates for future broadband wireless services. In this paper a novel signal detection scheme based on Grover's quantum search algorithm is proposed for MIMO-OFDM systems. Grover's quantum search algorithm is based on the concept and principles of quantum computing, such as quantum bit, quantum register and quantum parallelism. An analysis is given to the theoretical basis of Grover's algorithm and the performance of Grover's algorithm is evaluated. A novel signal detector based on Grover's algorithm (GD) for MIMO-OFDM system is proposed. The simulation results show that the proposed detector has more powerful properties in bit error rate than MMSE detector and VBLAST-MMSE detector. The performance of the proposed GD detector is close to optimal when the failure probability is 0.001. When the failure probability is 0.00001, the performance of GD detector declines. In this case, our proposed improved Grover's algorithm based detector is still close to the optimal ML detector. The complexity of GD and IGD is O(√N). It's much better than classical ML detector which complexity is O(N).
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| 4. |
- Li, Fei, et al.
(author)
-
Highly efficient oxidation of water by a molecular catalyst immobilized on carbon nanotubes
- 2011
-
In: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 50:51, s. 12276-12279
-
Journal article (peer-reviewed)abstract
- A successful team: A molecular device based on multiwalled carbon nanotubes functionalized by a mononuclear ruthenium catalyst has been shown to split water electrochemically (see picture; ITO=indium tin oxide). The readily prepared electrode showed excellent electrocatalytic activity for the oxidation of water, a high current density, and a low overpotential, and constitutes one step forward in the design of artificial photosynthetic systems.
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| 5. |
- Jiang, Yi, et al.
(author)
-
Promoting the Activity of Catalysts for the Oxidation of Water with Bridged Dinuclear Ruthenium Complexes
- 2013
-
In: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 52:12, s. 3398-3401
-
Journal article (peer-reviewed)abstract
- Solar fuels: Dinuclear ruthenium catalysts prepared from two covalently bridged monomeric catalytic units show outstanding activities towards the oxidation of water with high turnover numbers up to 43 000 and turnover frequencies up to 40 s-1 (see picture). Direct comparison of the performance parameters indicates that the dimers are significantly more active as catalysts than the monomers.
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| 6. |
- Li, Fei, et al.
(author)
-
A novel neural network optimized by quantum genetic algorithm for signal detection in MIMO-OFDM systems
- 2011
-
In: Computational Intelligence in Control and Automation (CICA). - : IEEE. - 9781424499038 - 9781424499021 ; , s. 170-177
-
Conference paper (peer-reviewed)abstract
- Neural networks can easily fall into a local extremum and have slow convergence rate. Quantum Genetic Algorithm (QGA) has features of small population size and fast convergence. Based on the investigation of QGA, we propose a novel neural network model, Radial Basis Function (RBF) networks optimized by Quantum Genetic Algorithm (QGA-RBF model). Then we investigate the performance of the proposed QGA-RBF on solving MIMO-OFDM signal detection problem. A novel signal detector based on QGA-RBF for MIMO-OFDM system is also proposed. The simulation results show that the proposed detector has more powerful properties in bit error rate than QGA based detector, RBF based detector and MMSE algorithm based detector, namely a 4-6 dB gain in performance can be achieved. The performance of the proposed detector is closer to optimal, compared with the other detectors.
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| 7. |
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| 8. |
- Li, Fei, et al.
(author)
-
Cognitive radio spectrum sharing using improved Quantum Genetic Algorithm
- 2011
-
In: 2011 International Conference on Wireless Communications and Signal Processing, WCSP 2011. - : IEEE. - 9781457710100 - 9781457710094
-
Conference paper (peer-reviewed)abstract
- A key challenge in cognitive radios (CR) network is how to adaptively and efficiently allocate transmission powers and spectrum among CR users according to the surrounding environment. In this paper, we propose a novel spectrum sharing based on our improved Quantum Genetic Algorithm (QGA) in a non-cooperative game for CR network. We improved the original QGA by quantum crossover operator, in order to overcome the shortcoming of the original QGA easily falling into a local extremum when used to optimize the continuous functions with many extrema. We used our improved QGA as a competitive strategy and conducted several simulations in two-user system and multi-user system. From simulation results, it is evident that the proposed improved QGA based spectrum sharing scheme has better convergence rate and higher sum capacity than GA based scheme even in multi-user CR system, namely up to 2bit/s/Hz increase in capacity. The simulation results also show that the population size of QGA affect sum capacity of cognitive radio system. The results demonstrated the effectiveness and the applicability of QGA in spectrum sharing in multi-user cognitive radio system.
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| 9. |
- Li, Fei, et al.
(author)
-
Improved quantum genetic algorithm for competitive spectrum sharing in cognitive radios
- 2012
-
In: 2011 International Conference in Electrics, Communication and Automatic Control Proceedings. - New York, NY : Springer. - 9781441988485 - 9781441988492 ; , s. 1203-1209
-
Conference paper (peer-reviewed)abstract
- This chapter investigates a kind of whole new approach to spectrum sharing in cognitive radio (CR) system, quantum-inspired approach. First, we improved Quantum Genetic Algorithm (QGA) by adding quantum crossover operator to overcome the shortcomings of the original QGA, easily falling into a local extremum when used to optimize the continuous functions with many extrema. We then propose a novel spectrum sharing scheme in noncooperative game for CR system based on our improved QGA. We use QGA as competitive strategies and provide simulation results that confirm the proposed schemes have better convergence rate and higher sum capacity than genetic algorithm (GA)-based scheme, namely at most 1 bit/s/Hz increase in capacity. The results demonstrate the effectiveness and the applicability of QGA in spectrum sharing in CR system.
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| 10. |
- Li, Fei, et al.
(author)
-
Innovation pedagogy and improving quality in higher education in web-based environments
- 2011
-
In: 2011 IEEE 3rd International Conference on Communication Software and Networks. - : IEEE. - 9781612844855 - 9781612844862 ; , s. 215-218
-
Conference paper (peer-reviewed)abstract
- Innovation is one of the main objectives for the higher education to meet the global challenges and to deliver the high levels of sustainable, knowledge-based growth. It is crucial to promote innovative pedagogy and improve quality. Based on the study of teaching programmes, pedagogies, web-based course management system and quality assurance system in engineering education at Umeå University, an innovative technology, Outcome-Based Approach, used in teaching at Umeå University is presented in this paper. The pedagogical experimentation taken by faculty teaching signal and system is described. Where the approach is successful is highlighted. The process of periodic review and revision of curricula is illustrated. The systematic quality work at Umeå University is described. Finally, some inspirations are drawn.
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| 11. |
- Li, Fei, et al.
(author)
-
Quantum Bacterial Foraging Optimization Algorithm
- 2014
-
In: 2014 IEEE CONGRESS ON EVOLUTIONARY COMPUTATION (CEC). - : IEEE Press. - 9781479914883 ; , s. 1265-1272
-
Conference paper (peer-reviewed)abstract
- This paper proposes a novel swarm intelligence optimization method which integrates bacterial foraging optimization (BFO) with quantum computing, called quantum bacterial foraging optimization (QBFO) algorithm. In QBFO, a multi-qubit which can represent a linear superposition of states in search space probabilistically is used to represent a bacterium, so that the quantum bacteria representation has a better characteristic of population diversity. A quantum rotation gate is designed to simulate the chemotactic step to drive the bacteria toward better solutions. Several tests are conducted based on benchmark functions including multi-peak function to evaluate optimization performance of the proposed algorithm. The numeric results show that the proposed QBFO has more powerful properties in convergence rate, stability and the ability of searching for the global optimal solution than the original BFO and quantum genetic algorithm. In addition, we applied our proposed QBFO to solve the traveling salesman problem, which is a well-known NP-hard problem in combinatorial optimization. The results indicate that the proposed QBFO shows better convergence behavior without premature convergence, and has more powerful properties in convergence rate, stability and the ability of searching for the global optimal solution, as compared to ant colony optimization algorithm and quantum genetic algorithm.
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| 12. |
- Li, Jian, et al.
(author)
-
Array Comparative Genomic Hybridization of Keratoacanthomas and Squamous Cell Carcinomas: Different Patterns of Genetic Aberrations Suggest Two Distinct Entities
- 2012
-
In: Journal of Investigative Dermatology. - : Elsevier BV. - 1523-1747 .- 0022-202X. ; 132:8, s. 2060-2066
-
Journal article (peer-reviewed)abstract
- Keratoacanthoma (KA) is a benign keratinocytic neoplasm that spontaneously regresses after 3-6 months and shares features with squamous cell carcinomas (SCCs). Furthermore, there are reports of KAs that have metastasized, invoking the question of whether KA is a variant of SCC (Hodak et al., 1993). To date, no reported criteria are sensitive enough to discriminate reliably between KA and SCC, and consequently there is a clinical need for discriminating markers. Our previous study analyzed 132 KAs and 29 SCCs and revealed significantly different regions of genomic aberrations using chromosomal comparative genomic hybridization (CGH). In the present study, we applied array CGH to investigate 98 KAs and 22 SCCs from the above samples. The result shows that all KAs and SCCs have some degree of genetic aberrations. The distribution of numbers of aberrant clones per sample differed significantly between KAs and SCCs (P<0.02), which also demonstrated recurrent aberrations that differed significantly (P<0.001), as illustrated by unsupervised cluster analysis. Classifiers for clinicopathological parameters of KAs were established based on t-test statistics and permutation tests. Tumor size, fibrosis, and inflammation, which are related to the developmental stages of KAs, showed significant (t-test, permutation test) associations with aberrations of selected genomic regions. This suggests chromosomal instability during the whole life cycle of KAs.
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| 13. |
- Lian, Ke-Yan, et al.
(author)
-
Big Bandgap in Highly Reduced Graphene Oxides
- 2013
-
In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 117:12, s. 6049-6054
-
Journal article (peer-reviewed)abstract
- It is generally believed that the bandgap of the graphene oxide is proportional to the concentration of the oxygen atoms and a highly reduced graphene oxide (rGO) without vacancy defects should be gapless. We show here from first principles calculations that the bandgap can be effectively opened even in low oxidation level with the absorption of oxygen atoms either symmetrically or asymmetrically. The properly arranged absorption can induce a bandgap up to 1.19 eV for a C/O ratio of 16/1 in a symmetric system and a bandgap up to 1.58 eV for a C/O ratio of 32/3 in an asymmetric system, at generalized gradient approximation (GGA) level. The hybridization between the in-plane p(xy) orbitals of oxygen atoms and the out-of-plane p(z) frontier orbital of graphene is responsible for the opening of the bandgap. This finding sheds new light on the bandgap engineering of graphene.
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| 14. |
- Zhang, Biaobiao, et al.
(author)
-
Electrochemical and Photoelectrochemical Water Oxidation by Supported Cobalt-Oxo Cubanes
- 2014
-
In: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 4:3, s. 804-809
-
Journal article (peer-reviewed)abstract
- Cobalt-oxo cubane clusters were immobilized on a Nafion film-coated fluorine-doped tin oxide (FTO) electrode and an alpha-Fe2O3 photoanode as surface catalysts for water oxidation. The performance of electrochemical water splitting indicated that these earth-abundant metal complexes retain their homogeneous reactivity on the electrode. Furthermore, efficient visible light-driven water oxidation was realized by coupling a molecular electrocatalyst with an inorganic semiconductor as a noble metal-free photoanode, showing a stability significantly improved with respect to that of the homogeneous system.
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| 15. |
- Zhang, Biaobiao, et al.
(author)
-
Homogeneous Oxidation of Water by Iron Complexes with Macrocyclic Ligands
- 2014
-
In: Chemistry - An Asian Journal. - : Wiley. - 1861-4728 .- 1861-471X. ; 9:6, s. 1515-1518
-
Journal article (peer-reviewed)abstract
- The activity of eleven separated iron complexes and nine in situ-generated iron complexes towards catalytic water oxidation have been examined in aqueous solutions with Ce(NH4)(2)(NO3)(6) as the oxidant. Two iron complexes bearing tridentate and tetradentate macrocyclic ligands were found to be novel water oxidation catalysts. The one with tetradentate ligand exhibited a promising activity with a turnover number of 65 for oxygen evolution.
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| 16. |
- Zhou, Xu, et al.
(author)
-
Photocatalytic Water Oxidation by Molecular Assemblies Based on Cobalt Catalysts
- 2014
-
In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 7:9, s. 2453-2456
-
Journal article (peer-reviewed)abstract
- Chromophore-catalyst molecular assemblies towards visible light-driven water oxidation were synthesized by covalent integration of a light-harvesting complex [Ru(bpy)(3)](2+) (bpy= 2,2'-bipyridine) and a Co4O4 cubane water oxidation catalyst. The two components were assembled either in linear or macrocyclic configurations. In the presence of the sacrificial reagent, the Ru-Co metallocycle exhibits remarkable photocatalytic activity for oxygen evolution, which is one order of magnitude higher than that of a multicomponent system and exceeds that of a linear assembly by a factor of five, offering access to highly active photocatalyst through molecular design.
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| 17. |
- Abel, Martin, et al.
(author)
-
Collision-induced absorption by supermolecular complexes from a new potential energy and induced dipole surface, suited for calculations up to thousands of kelvin
- 2010
-
In: 20th International Conference on Spectral Line Shapes. - Melville, NY : American Institute of Physics (AIP). - 9780735408456 ; , s. 251-257
-
Conference paper (peer-reviewed)abstract
- Absorption by pairs of H2 molecules is an important opacity source in the atmospheres of the outer planets, and thus of special astronomical interest. The emission spectra of cool white dwarf stars differ significantly from the expected blackbody spectra, amongst other reasons due to absorption by H2-H2, H2-He, and H2-H collisional complexes in the stellar atmospheres. To model the radiative processes in these atmospheres, which have temperatures of several thousand kelvin, one needs accurate knowledge of the induced dipole (ID) and potential energy surfaces (PES) of such collisional complexes. These come from quantum-chemical calculations with the H2 bonds stretched or compressed far from equilibrium. Laboratory measurements of collision-induced (CI) absorption exist only at much lower temperature. For H2 pairs at room temperature, the calculated spectra of the rototranslational band, the fundamental band, and the first overtone match the experimental data very well. In addition, with the newly obtained IDS it became possible to reproduce the measurements in the far blue wing of the rototranslational spectrum of H2 at 77.5 K, as well as at 300 K. Similarly good agreement between theory and measurement is seen in the fundamental band of molecular deuterium at room temperature. Furthermore, we also show the calculated absorption spectra of H2-He at 600 K and of H2-H2 at 2,000 K, for which there are no experimental data for comparison
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| 18. |
- Asayama, Kei, et al.
(author)
-
Setting Thresholds to Varying Blood Pressure Monitoring Intervals Differentially Affects Risk Estimates Associated With White-Coat and Masked Hypertension in the Population
- 2014
-
In: Hypertension. - 0194-911X .- 1524-4563. ; 64:5, s. 935-942
-
Journal article (peer-reviewed)abstract
- Outcome-driven recommendations about time intervals during which ambulatory blood pressure should be measured to diagnose white-coat or masked hypertension are lacking. We cross-classified 8237 untreated participants (mean age, 50.7 years; 48.4% women) enrolled in 12 population studies, using >= 140/>= 90, >= 130/>= 80, >= 135/>= 85, and >= 120/>= 70 mm Hg as hypertension thresholds for conventional, 24-hour, daytime, and nighttime blood pressure. White-coat hypertension was hypertension on conventional measurement with ambulatory normotension, the opposite condition being masked hypertension. Intervals used for classification of participants were daytime, nighttime, and 24 hours, first considered separately, and next combined as 24 hours plus daytime or plus nighttime, or plus both. Depending on time intervals chosen, white-coat and masked hypertension frequencies ranged from 6.3% to 12.5% and from 9.7% to 19.6%, respectively. During 91 046 person-years, 729 participants experienced a cardiovascular event. In multivariable analyses with normotension during all intervals of the day as reference, hazard ratios associated with white-coat hypertension progressively weakened considering daytime only (1.38; P=0.033), nighttime only (1.43; P=0.0074), 24 hours only (1.21; P=0.20), 24 hours plus daytime (1.24; P=0.18), 24 hours plus nighttime (1.15; P=0.39), and 24 hours plus daytime and nighttime (1.16; P=0.41). The hazard ratios comparing masked hypertension with normotension were all significant (P<0.0001), ranging from 1.76 to 2.03. In conclusion, identification of truly low-risk white-coat hypertension requires setting thresholds simultaneously to 24 hours, daytime, and nighttime blood pressure. Although any time interval suffices to diagnose masked hypertension, as proposed in current guidelines, full 24-hour recordings remain standard in clinical practice.
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| 19. |
- Bianchi, Marco, et al.
(author)
-
Robust Surface Doping of Bi2Se3 by Rubidium Intercalation
- 2012
-
In: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 6:8, s. 7009-7015
-
Journal article (peer-reviewed)abstract
- Rubidium adsorption on the surface of the topological insulator Bi2Se3 is found to induce a strong downward band bending, leading to the appearance of a quantum-confined two-dimensional electron gas state (2DEG) in the conduction band. The 2DEG shows a strong Rashba-type spin orbit splitting, and it has previously been pointed out that this has relevance to nanoscale spintronics devices. The adsorption of Rb atoms, on the other hand, renders the surface very reactive, and exposure to oxygen leads to a rapid degrading of the 2DEG. We show that intercalating the Rb atoms, presumably into the van der Waals gaps in the quintuple layer structure of Bi2Se3, drastically reduces the surface reactivity while not affecting the promising electronic structure. The intercalation process is observed above room temperature and accelerated with increasing initial Rb coverage, an effect that is ascribed to the Coulomb interaction between the charged Rb ions. Coulomb repulsion is also thought to be responsible for a uniform distribution of Rb on the surface.
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| 20. |
- Boonyavong, Narumon, et al.
(author)
-
Synthesis, electrochemistry and photo-induced electron transfer of unsymmetrical dinuclear ruthenium osmium 2,2 '-bipyridine complexes
- 2014
-
In: Journal of Photochemistry and Photobiology A. - : Elsevier BV. - 1010-6030 .- 1873-2666. ; 287, s. 40-48
-
Journal article (peer-reviewed)abstract
- Four unsymmetric dinuclear ruthenium and osmium complexes, Os(bpy)(3)-viologen-Ru(bpy)(3) (1; bpy= 2,2'-bipyridyl), Ru(bpy)(3)-viologen-Ru(bpy)(dcbpy)(2) (2; dcbpy= 4,4'-dicarboxy1-2,2-bipyridyl), Os(bpy)(3)-viologen-Ru(bpy)(dcbpy)(2) (3) and rotaxane 1 subset of CB[7] (CB[7] = cucurbit[7]uril), were successfully synthesized. The NMR, electrochemistry and photochemistry studies of these complexes were performed in non-aqueous solutions. The results show that the CB[7] host mainly locates at the butyl linker part of the osmium side in an acetonitrile solution. This binding lowers the oxidation potential of osmium whereas the oxidation potential of ruthenium does not change. The oxidation potential of ruthenium in complexes 2 and 3 is higher due to the electron withdrawing property of carboxylic anchor groups. Analysis with UV-vis spectra shows the viologen radical formation and reversed process of these complexes in non-aqueous solutions.
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| 21. |
- Brguljan-Hitij, Jana, et al.
(author)
-
Risk Stratification by Ambulatory Blood Pressure Monitoring Across JNC Classes of Conventional Blood Pressure
- 2014
-
In: American Journal of Hypertension. - : Oxford University Press (OUP). - 0895-7061 .- 1941-7225. ; 27:7, s. 956-965
-
Journal article (peer-reviewed)abstract
- BACKGROUND Guidelines propose classification of conventional blood pressure (CBP) into normotension (<120/<80 mm Hg), prehypertension (120-139/80-89 mm Hg), and hypertension (>140/>90 mm Hg). METHODS To assess the potential differential contribution of ambulatory blood pressure (ABP) in predicting risk across CBP strata, we analyzed outcomes in 7,826 untreated people recruited from 11 populations. RESULTS During an 11.3-year period, 809 participants died (276 cardiovascular deaths) and 639, 383, and 225 experienced a cardiovascular, cardiac, or cerebrovascular event. Compared with normotension (n = 2,639), prehypertension (n = 3,076) carried higher risk (P <= 0.015) of cardiovascular (+ 41%) and cerebrovascular (+ 92%) endpoints; compared with hypertension (n = 2,111) prehypertension entailed lower risk (P <= 0.005) of total mortality (-14%) and cardiovascular mortality (-29%) and of cardiovascular (-34%), cardiac (-33%), or cerebrovascular (-47%) events. Multivariable-adjusted hazard ratios (HRs) for stroke associated with 24-hour and daytime diastolic ABP (+ 5 mm Hg) were higher (P <= 0.045) in normotension than in prehypertension and hypertension (1.98 vs. 1.19 vs. 1.28 and 1.73 vs. 1.09 vs. 1.24, respectively) with similar trends (0.03 <= P <= 0.11) for systolic ABP (+10 mm Hg). However, HRs for fatal endpoints and cardiac events associated with ABP did not differ significantly (P >= 0.13) across CBP categories. Of normotensive and prehypertensive participants, 7.5% and 29.3% had masked hypertension (daytime ABP >= 135/>= 85 mm Hg). Compared with true normotension (P <= 0.01), HRs for stroke were 3.02 in normotension and 2.97 in prehypertension associated with masked hypertension with no difference between the latter two conditions (P = 0.93). CONCLUSION ABP refines risk stratification in normotension and prehypertension mainly by enabling the diagnosis of masked hypertension.
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| 22. |
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| 23. |
- ChengWen, Xing, et al.
(author)
-
Statistically robust resource allocation for distributed multi-carrier cooperative networks
- 2013
-
In: Science China Information Sciences. - : Springer. - 1674-733X .- 1869-1919. ; 56:2, s. 109-121
-
Journal article (peer-reviewed)abstract
- In this paper, we investigate joint subcarrier and power allocation scheme for distributed multi-carrier cooperative networks with imperfect channel state information. Using practical channel estimation algorithms, the statistic model of the channel estimation error is first derived. Then based on the channel error model, the resource allocation scheme aims at maximizing the sum rate of the overall network. Specifically, both subcarrier allocation and power allocation are taken into account. In the subcarrier allocation, a realistic problem of the power leakage between neighboring subcarriers is also addressed. Furthermore, based on Lagrange dual-decomposition algorithm, a practical power allocation algorithm is proposed. Finally, the simulation results demonstrate the performance advantages of the proposed robust design.
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| 24. |
- Deng, Min, et al.
(author)
-
Genome-wide association analyses in Han Chinese identify two new susceptibility loci for amyotrophic lateral sclerosis
- 2013
-
In: Nature Genetics. - : Nature Publishing Group. - 1061-4036 .- 1546-1718. ; 45:6, s. 697-
-
Journal article (peer-reviewed)abstract
- To identify susceptibility genes for amyotrophic lateral sclerosis (ALS), we conducted a genome-wide association study (GWAS) in 506 individuals with sporadic ALS and 1,859 controls of Han Chinese ancestry. Ninety top SNPs suggested by the current GWAS and 6 SNPs identified by previous GWAS were analyzed in an independent cohort of 706 individuals with ALS and 1,777 controls of Han Chinese ancestry. We discovered two new susceptibility loci for ALS at 1q32 (CAMK1G, rs6703183, P-combined = 2.92 x 10(-8), odds ratio (OR) = 1.31) and 22p11 (CABIN1 and SUSD2, rs8141797, P-combined = 2.35 x 10(-9), OR = 1.52). These two loci explain 12.48% of the overall variance in disease risk in the Han Chinese population. We found no association evidence for the previously reported loci in the Han Chinese population, suggesting genetic heterogeneity of disease susceptibility for ALS between ancestry groups. Our study identifies two new susceptibility loci and suggests new pathogenic mechanisms of ALS.
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| 25. |
- Ding, Fei, et al.
(author)
-
Ultrabroadband strong light absorption based on thin multilayered metamaterials
- 2014
-
In: Laser & Photonics reviews. - : Wiley. - 1863-8880 .- 1863-8899. ; 8:6, s. 946-953
-
Journal article (peer-reviewed)abstract
- Light absorbers have drawn intensive attention as crucial components for solar-energy harvesting, thermal emission tailoring, modulators, etc. However, achievement of light absorbers with wide bandwidth remains a challenge thus far. Here, a thin, unprecedentedly ultrabroadband strong light absorber is proposed and experimentally demonstrated, which consists of periodic taper arrays constructed by an alumina-chrome multilayered metamaterial (MM) on a gold substrate. This MM can change from a hyperbolic material to an anisotropic dielectric material at different frequency ranges and the special material features are the fundamental origins of the ultrabroadband absorption. The absorber is quite insensitive to the incident angle, and can be insensitive to the polarization. One two-dimensional periodic array of 400-nm height MM tapers is fabricated. The measured absorption is over 90% over almost the entire solar spectrum, reaching an average level of 96%, and remains high (above 85%) even in the longer-wavelength range till 4 m. The proposed absorbers open up a new avenue to realize broadband thin light-harvesting structures.
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| 26. |
- Fei, Xiaowen, et al.
(author)
-
A novel negative Fe-deficiency-responsive element and a TGGCA-type-like FeRE control the expression of FTR1 in Chlamydomonas reinhardtii.
- 2010
-
In: Journal of Biomedicine and Biotechnology. - : Hindawi Limited. - 1110-7243 .- 1110-7251. ; 2010, s. 790247-
-
Journal article (peer-reviewed)abstract
- We have reported three Fe-deficiency-responsive elements (FEREs), FOX1, ATX1, and FEA1, all of which are positive regulatory elements in response to iron deficiency in Chlamydomonas reinhardtii. Here we describe FTR1, another iron regulated gene and mutational analysis of its promoter. Our results reveal that the FeREs of FTR1 distinguish itself from other iron response elements by containing both negative and positive regulatory regions. In FTR1, the -291/-236 region from the transcriptional start site is necessary and sufficient for Fe-deficiency-inducible expression. This region contains two positive FeREs with a TGGCA-like core sequence: the FtrFeRE1 (ATGCAGGCT) at -287/-279 and the FtrFeRE2 (AAGCGATTGCCAGAGCGC) at -253/-236. Furthermore, we identified a novel FERE, FtrFeRE3 (AGTAACTGTTAAGCC) localized at -319/-292, which negatively influences the expression of FTR1.
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| 27. |
- Fei, Z., et al.
(author)
-
Forbidden-line spectroscopy of the ground-state configuration of Cd-like W
- 2014
-
In: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 90:5
-
Journal article (peer-reviewed)abstract
- only using electric-dipole forbidden emission lines, in what we label forbidden-line spectroscopy, we identified several energy levels in cadmium-like tungsten, W26+. The spectrum was recorded at the Shanghai permanentmagnet electron beam ion trap in the visible region. The identifications were supported by large-scale multiconfiguration Dirac-Hartree-Fock calculations which involved careful investigations of core-valence and core-core correlation effects, and by relativistic many-body perturbation theory calculations. With this novel method we identified in all seven lines and measured their wavelengths. From this we can determine the relative position of seven energy levels. Due to the close degeneracy of two levels, we give alternative energies for three of the levels.
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| 28. |
- Frommhold, Lothar, et al.
(author)
-
Infrared atmospheric emission and absorption by simple molecular complexes, from first principles
- 2010
-
In: Molecular Physics. - : Informa UK Limited. - 0026-8976 .- 1362-3028. ; 108:17, s. 2265-2272
-
Journal article (peer-reviewed)abstract
- Quantum chemical methods are used to obtain the interaction-induced dipole surfaces (IDS) of complexes of two interacting (i.e. colliding) molecules, for example H2–H2, H2–He, etc., collisional complexes, along with their potential energy surfaces (PES). Eight H2 bond distances, from 0.942 to 2.801 bohr, are chosen for each H2 molecule to account for rotovibrational excitations. Rotovibrational matrix elements of these ID and PE surfaces are computed as necessary for the study of supermolecular (‘collision-induced’) absorption spectra of dense hydrogen gas, and of gaseous mixtures of hydrogen and helium, at temperatures up to several thousand kelvin and for frequencies from 0 to those of several H2 overtone bands. Rotovibrational state to state scattering calculations couple the collisional complex perturbatively to single photons. The absorption process causes rotovibrational transitions in one molecule, or simultaneous transitions in both molecules (when H2–H2 collisional complexes are considered). The spectral profiles of tens of thousands of such transitions are computed from first principles. Individual ‘lines’ are very broad so that they overlap substantially, forming a supermolecular quasi-continuum. The comparison of the computed collision-induced absorption (CIA) spectra with existing laboratory measurements at low temperatures (≤ 300 K) shows close agreement so that our results for higher temperatures, where laboratory experiments do not exist, may be used with confidence. Similar calculations of CIA spectra at high temperatures and frequencies are underway for other collisional systems (e.g. H2–H) of interest in astrophysical applications (e.g. ‘cool’ stellar atmospheres). Collision-induced Raman spectra (CIRS) have been similarly obtained; computed Raman spectra also compare favourably with existing laboratory measurements.
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| 29. |
- Hansen, Malte, et al.
(author)
-
Photocatalytic water oxidation at soft interfaces
- 2014
-
In: CHEM SCI. - : Royal Society of Chemistry (RSC). - 2041-6520 .- 2041-6539. ; 5:7, s. 2683-2687
-
Journal article (peer-reviewed)abstract
- Molecular water oxidation catalysts have been, for the first time, co-embedded with a photosensitizer into phospholipid membranes. The functionalized small unilamellar vesicles produce molecular oxygen by photocatalysis when irradiated with visible light in aqueous buffer. The two dimensional assembly of the catalysts at the lipid-water interface mimics photoactive membranes in biology and allows photocatalytic water oxidation at very low catalyst concentrations of 500 nM, which cannot be reached in homogeneous systems. Highest TONs are obtained below the membrane's main transition temperature indicating that phase separation, clustering and a limited dynamic enhance the photocatalytic activity of the assembly. The concept of membrane co- embedding can be applied to various combinations, ratios and concentrations of photosensitizers and water oxidizing catalysts, providing a new approach for artificial photosynthesis.
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| 30. |
- Jiang, Yi, et al.
(author)
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Chemical and photocatalytic water oxidation by mononuclear Ru catalysts
- 2013
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In: Cuihuà xuébào. - 0253-9837 .- 1872-2067. ; 34:8, s. 1489-1495
-
Journal article (peer-reviewed)abstract
- Four mononuclear Ru complexes with different substituents on the para position of the pyridine ligand of Ru(bda)(pic)(2) (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; pic = picoline) were synthesized and characterized by H-1 nuclear magnetic resonance or X-ray crystallography. The electrochemical properties of this series of compounds in acidic and neutral conditions were studied by cyclic voltammetry. Their catalytic activity towards water oxidation was investigated using a chemical oxidant ([Ce(NH4)(2)(NO3)(6)] (Ce-IV) in acidic solution, or driven by visible light in a three-component system containing a photosensitizer ([Ru(bpy)(3)](2+)) and an electron acceptor (S2O82-). For the chemical water oxidation, complex 1 was found to be the most effective, exhibiting a turnover number (TON) of up to 4000. The pyridine substituent at the 4-position in 1 may be protonated giving an intensive electron-withdrawing effect. Complex 2 bears the most electron-withdrawing trifluoromethyl group under neutral conditions and showed the highest photocatalytic activity with a TON of 270 over 2 h. It was concluded that the more electron-withdrawing substituents led to higher activity towards oxygen evolution for this type of Ru catalysts in the oxidation of water.
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| 31. |
- Li, Fei, et al.
(author)
-
Proactive Service Discovery in Pervasive Environments
- 2010
-
In: Proceedings of the 7th ACM International Conference on Pervasive Services (ICPS). ; , s. 126-133
-
Conference paper (peer-reviewed)abstract
- Pervasive environments are characterized by rich and dy-namic context, where users need to be continuously informed about services relevant to their current context. Implicit discovery requests, triggered by changes of user context, avail-able services, or user preferences are prevalent in such environments.This paper proposes a proactive service discovery approach for pervasive environments to address these implicit requests. Services and user preferences are described by a formal context model, which effectively captures the dynamics of context and the relationship between services and users. Based on the model, we propose a proactive discovery algorithm to continuously present the most relevant services to the user in response to changes of context, services or user preferences. Numeric coding methods are applied in different phases of the algorithm to improve its performance. A proactive service discovery system is proposed and the context model is grounded in a smart home environment. Experimental results show that our approach can efficiently provide the user with up-to-date information about useful services.
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| 32. |
- Li, Fei, et al.
(author)
-
Towards A Solar Fuel Device : Light-Driven Water Oxidation Catalyzed by a Supramolecular Assembly
- 2012
-
In: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 51:10, s. 2417-2420
-
Journal article (peer-reviewed)abstract
- Time to split: Supramolecular assemblies containing both photosensitizers and a ruthenium water-oxidation catalyst were prepared and characterized. The pictured assembly exhibits, for the first time, enhanced visible-light-driven water oxidation activity.
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| 33. |
- Li, Jiantong, et al.
(author)
-
A simple route towards high-concentration surfactant-free graphene dispersions
- 2012
-
In: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 50:8, s. 3113-3116
-
Journal article (peer-reviewed)abstract
- A simple solvent exchange method is introduced to prepare high-concentration and surfactant-free graphene liquid dispersion. Natural graphite flakes are first exfoliated into graphene in dimethylformamide (DMF). DMF is then exchanged by terpineol through distillation, relying on their large difference in boiling points. Graphene can then be concentrated thanks to the volume difference between DMF and terpineol. The concentrated graphene dispersions are used to fabricate transparent conductive thin films, which possess comparable properties to those prepared by more complex methods.
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| 34. |
- Li, Jiantong, et al.
(author)
-
Efficient inkjet printing of graphene
- 2013
-
In: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 25:29, s. 3985-3992
-
Journal article (peer-reviewed)abstract
- An efficient and mature inkjet printing technology is introduced for mass production of coffee-ring-free patterns of high-quality graphene at high resolution (unmarked scale bars are 100 μm). Typically, several passes of printing and a simple baking allow fabricating a variety of good-performance electronic devices, including transparent conductors, embedded resistors, thin film transistors, and micro-supercapacitors.
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| 35. |
- Li, Xiaoping, et al.
(author)
-
Collision-induced dipoles and polarizabilities of pairs of hydrogen molecules : Ab initio calculations and results from spherical tensor analysis
- 2012
-
In: International Conference of Computational Methods in Sciences and Engineering 2009. - Melville, NY : American Institute of Physics (AIP). - 9780735411227 ; , s. 100-135
-
Conference paper (peer-reviewed)abstract
- New ab initio results are reported for the interaction-induced changes in the dipole moments and polarizabilities of pairs of hydrogen molecules, computed using finite-field coupled-cluster methods in MOLPRO 2000 and GAMESS, with an aug-cc-pV5Z (spdf) basis set. Earlier work by X. Li, C. Ahuja, J. F. Harrison, and K. L. C. Hunt, J. Chem. Phys. 126, 214302 (2007), on collision-induced polarizabilities Δα has been extended with 170 additional geometrical configurations of the H2 pairs. In calculations of Δα, we have used a "random field" technique, with up to 120 different field strengths, having components that range from 0.001 to 0.01 a.u. Numerical tests show that the pair dipoles Δμ can be obtained accurately from calculations limited to 6 values of the field in each direction, so this approach has been used to compute Δμ by X. Li, K. L. C. Hunt, F. Wang, M. Abel, and L. Frommhold, Int. J. Spectroscopy 2010, 371201 (2010). We have evaluated the collision-induced dipoles of H2 pairs for 28 combinations of bond lengths (ranging from 0.942 a.u. to 2.801 a.u.), 7 intermolecular separations R, and 17 different relative orientations. In our work on Δα, the bond lengths are fixed at 1.449 a.u. Our results agree well with the previous ab initio work of W. Meyer, A. Borysow, and L. Frommhold, Phys. Rev. A 40, 6931 (1989), and of Y. Fu, C. G. Zheng and A. Borysow, J. Quant. Spectroscopy and Rad. Transfer, 67, 303 (2000)-where those data exist-for Δμ of H2 pairs. For Δα, our results agree well with the CCSD(T) results obtained by G. Maroulis, J. Phys. Chem. A 104, 4772 (2000) for two pair orientations and fixed R. The pair polarizability anisotropies also agree well with the small-basis self-consistent field results of D. G. Bounds, Mol. Phys. 38, 2099 (1979), although the trace of the polarizability differs by factors of 2 or more from Bounds' results. We have determined the expansion coefficients for Δμ and Δα, expressed as series in the spherical harmonics of the orientation angles of the intermolecular vector and of unit vectors along the molecular axes. The leading coefficients converge at long range to the predictions from perturbation theory, derived by J. E. Bohr and K. L. C. Hunt, J. Chem. Phys. 87, 3821 (1987); T. Bancewicz, W. G.az, and S. Kielich, Chem. Phys. 128, 321 (1988); and X. Li and K. L. C. Hunt, J. Chem. Phys. 100, 7875 (1994); ibid, 9276 (1994). Based on our results for Δμ, we find excellent agreement for the binary rototranslational absorption spectrum of H2 at 297.5 K as calculated by X. Li, K. L. C. Hunt, F. Wang, M. Abel, and L. Frommhold, Int. J. Spectroscopy 2010, 371201 (2010) and as determined experimentally by G. Bachet, E. R. Cohen, P. Dore, and G. Birnbaum, Can. J. Phys. 61, 591 (1983), out to ∼1500 cm-1. We have also calculated the vibrational spectra out to 20,000 cm-1, at T = 600 K, 1000 K, and 2000 K, for which there are no experimental data. We are currently working to extend the temperature range in the calculations to 7000 K, for application in modeling the spectra of cool white dwarf stars. We have used the results for Δα to calculate collision-induced rototranslational Raman spectra for H2 pairs [M. Gustafsson, L. Frommhold, X. Li, and K. L. C. Hunt, J. Chem. Phys. 130, 164314 (2009)]. Experimental results for the Raman spectra have been reported by U. Bafile, M. Zoppi, F. Barocchi, M. S. Brown, and L. Frommhold, Phys. Rev. A 40, 1654 (1989); U. Bafile, L. Ulivi, M. Zoppi, F. Barocchi, M. Moraldi, and A. Borysow, Phys. Rev. A 42, 6916 (1990); and M. S. Brown, S.-K. Wang, and L. Frommhold, Phys. Rev. A 40, 2276 (1989). Agreement between our calculations and experiment is good for both the polarized and depolarized spectra, with the remaining discrepancies probably attributable to the difference between the static (calculated) and frequency-dependent (experimental) values of Δα.
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| 36. |
- Li, Xiao-Fei, et al.
(author)
-
Conductivity of carbon-based molecular junctions from ab-initio methods
- 2014
-
In: Frontiers of Physics. - : Springer Science and Business Media LLC. - 2095-0462 .- 2095-0470. ; 9:6, s. 748-759
-
Research review (peer-reviewed)abstract
- Carbon nanomaterials (CNMs) are prompting candidates for next generational electronics. In this review we provide a mini overview of recent results on the conductivity of carbon-based molecular junctions obtained from ab-initio methods. CNMs used as nanoelectrodes and molecular materials in molecular junctions are discussed. The functionalities that include the nanomechanically controlled molecular conductance switches, negative differential resistance devices, and electronic rectifiers realized by using CNMs have been demonstrated.
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| 37. |
- Li, Xiao-Fei, et al.
(author)
-
Design of Graphene-Nanoribbon Heterojunctions from First Principles
- 2011
-
In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:25, s. 12616-12624
-
Journal article (peer-reviewed)abstract
- Graphene nanoribbons with armchair and zigzag edges are known to have very different electronic structure and properties. We show here that the fusion of an armchair and a zigzag graphene-nanoribbon (aGNR vertical bar zGNR) can form heterojunctions with remarkable electron transport properties. First-principles calculations reveal that the heterojunction can be either metallic or semiconducting depending on the width of the nanoribbon. A well-defined oscillation of the zero-bias conductance as a function of the ribbon width is observed, which is originated from the resonance and nonresonance of frontier orbitals between aGNR and zGNR We find that the current/voltage characteristics of the aGNR vertical bar zGNR heterojunction possess pronounced rectification effect, and a high rectification ratio can be achieved by tuning the width of the zGNR to minimize the backward current. The unique properties of the proposed heterojunction could be very useful for manufacturing graphene-based electronic devices.
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| 38. |
- Li, Xiao-Fei, et al.
(author)
-
Effects of Interface Roughness on Electronic Transport Properties of Nanotube-Molecule-Nanotube Junctions
- 2010
-
In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:28, s. 12335-12340
-
Journal article (peer-reviewed)abstract
- We investigate electronic transport properties of molecular junctions constructed by a single conjugated molecule attached in the gap of two broken metallic single walled carbon nanotubes (CNTs). With the help of molecular dynamic simulations (MD), we have provided a realistic description for mechanical stretching processes of different carbon nanotubes and contact structures between the broken CNTs and the conjugated molecule in different junctions. Statistical analysis shows that the molecule generally prefers to be titled inside the junctions with polygonal contact, in particular the apex at the broken ends of tubes. Nonequilibrium Green's function (NEGF) calculations reveal that such realistic CNTs-molecular junctions have very different electron transport properties from junctions with ideal SWCNTs as electrodes. The statistically and energetically favorable CNTs-molecular junctions of different chiralities are found to be always metallic, but their absolute conductance is sensitive to the chirality of the tube. It is suggested that with armchair CNTs as electrodes, a better conductivity can be obtained. The calculated current-voltage characteristics of junctions with realistic contact geometries are in good agreement with experiments.
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| 39. |
- LI, Xiao-Fei, 1973-
(author)
-
Electron and Spin Transport in Graphene-Based Nanodevices
- 2013
-
Doctoral thesis (other academic/artistic)abstract
- This thesis is devoted to the multi-scale modeling of electron and spin transport in graphene-based nanodevices. Several devices with fascinating structures and attractive properties have been designed by means of state-of-the-art computational methods, which include ab-initio molecular dynamics (MD) simulations for the geometry, density functional theory (DFT) for the electronic structure, and non-equilibrium Green’s functions (NEGF) for carriers transport properties.Poly-crystalline graphenes offer ample opportunities to make devices with desirable properties. We have systematically studied a type of poly-crystalline graphene constructed by zigzag and armchair graphene nanoribbons (ZGNR and AGNR). It is found that the choice of the supercells in modeling with periodic boundary conditions (PBC) has strong implications on the electronic and magnetic properties of such hybrid systems. A model with minimal lattice mismatch is obtained, which could be regarded as the most appropriate model for hybrid GNRs. With this model, it is revealed that the hybrid GNR is of ferromagnetism with a high Curie temperature. We have then designed armchair/zigzag graphene nanoribbon heterojunctions (AGNR|ZGNR) with a well-defined conductance oscillation and rectification behavior. It is shown that the resonance or nonresonance of the frontier orbitals between AGNR and ZGNR is the source of the oscillation and the asymmetric structure is the root of the rectification. A high rectification ratio can be achieved by tuning the width of ZGNR to enhance the asymmetric character of transmission function and to minimize the backward current.The electron transport properties of graphene can be modified by hydrogenation strips (HSs) formed from the absorbed hydrogen atoms. We have designed a new graphene nanoribbon that has zigzag-edged HSs placed at its middle region. It is found that the HS can electrically separate the GNR into sub-GNRs and each HS introduces two spin-polarized conducting edge-like states around the Fermi level. This leads to a significant enhancement of the conductance and the spinpolarization. We have also found that by introducing embedding a short sp3-edged section into the sp2-edged ZGNRs or a short sp2-edged section into the sp3-edged ZGNRs, the orbital symmetry mismatch between these two sections can induce the opening of the conductance energy gap in ZGNRs over a wide energy region. This simple strategy explains many unexplained experimental results and offers a simple strategy to design GNRs with a proper energy gap.We have also carefully examined the spin-polarization of chiral GNRs with reconstructed (2,1)-edges. It is found that the unsaturated (2,1)-edged chiral GNRs can possess strong current polarizations (nearly 100%) and a striking negative differential resistance (NDR) behavior.
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| 40. |
- Li, Xiao-Fei, et al.
(author)
-
Electronic transport through zigzag/armchair graphene nanoribbon heterojunctions
- 2012
-
In: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 24:9, s. 095801-
-
Journal article (peer-reviewed)abstract
- The electronic transport properties of a graphene nanoribbon (GNR) are known to be sensitive to its width, edges and defects. We investigate the electronic transport properties of a graphene nanoribbon heterojunction constructed by fusing a zigzag and an armchair graphene nanoribbon (zGNR/aGNR) side by side. First principles results reveal that the heterojunction can be either metallic or semiconducting, depending on the width of the nanoribbons. Intrinsic rectification behaviors have been observed, which are largely sensitive to the connection length between the zGNR and aGNR. The microscopic origins of the rectification behavior have been revealed. We find that the carrier type can alter from electrons to holes with the bias voltage changing from negative to positive; the asymmetrical transmission spectra of electrons and holes induced by the interface defects directly results in the rectification behavior. The results suggest that any methods which can enhance the asymmetry of the transmission spectra between holes and electrons could be used to improve the rectification behavior in the zGNR/aGNR heterojunction. Our findings could be useful for designing graphene based electronic devices.
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| 41. |
- Li, Xiao-Fei, et al.
(author)
-
Strong current polarization and negative differential resistance in chiral graphene nanoribbons with reconstructed (2,1)-edges
- 2012
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:7, s. 073101-
-
Journal article (peer-reviewed)abstract
- We investigate electronic structures and transport properties of chiral-graphene-nanoribbons (CGNRs) with reconstructed (2,1)-edges. First principles results reveal that the (2,1)-CGNRs can be either spin non-polarized or polarized, depending on whether the edges are H-saturated or unsaturated. H-saturated systems are semiconductors with width-dependent transmission gap, while unsaturated systems are metallic at non-polarized state or at antiferromagnetic state and they are semiconductors at ferromagnetic state. Moreover, unsaturated systems possess strong current polarizations (nearly 100%) and a striking negative differential resistance behavior (with a peak-to-valley ratio about 105). These remarkable properties suggest the potential application of (2,1)-CGNRs in molectronics and spintronics.
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| 42. |
- Li, Xiao-Fei, et al.
(author)
-
Tuning electron transport through a single molecular junction by bridge modification
- 2014
-
In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 116:1, s. 013701-
-
Journal article (peer-reviewed)abstract
- The possibility of controlling electron transport in a single molecular junction represents the ultimate goal of molecular electronics. Here, we report that the modification of bridging group makes it possible to improve the performance and obtain new functions in a single cross-conjugated molecular junction, designed from a recently synthesized bipolar molecule bithiophene naphthalene diimide. Our first principles results show that the bipolar characteristic remains after the molecule was modified and sandwiched between two metal electrodes. Rectifying is the intrinsic characteristic of the molecular junction and its performance can be enhanced by replacing the saturated bridging group with an unsaturated group. A further improvement of the rectifying and a robust negative differential resistance (NDR) behavior can be achieved by the modification of unsaturated bridge. It is revealed that the modification can induce a deviation angle about 4 degrees between the donor and the acceptor pi-conjugations, making it possible to enhance the communication between the two pi systems. Meanwhile, the low energy frontier orbitals of the junction can move close to the Fermi level and encounter in energy at certain biases, thus a transport channel with a considerable transmission can be formed near the Fermi level only at a narrow bias regime, resulting in the improvement of rectifying and the robust NDR behavior. This finding could be useful for the design of single molecular devices.
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| 43. |
- Li, Xiao-Fei, et al.
(author)
-
Tuning the Electronic Transport Properties of Zigzag Graphene Nanoribbons via Hydrogenation Separators
- 2011
-
In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:49, s. 24366-24372
-
Journal article (peer-reviewed)abstract
- Hydrogenation technique is known to be useful for opening up the band gap and controlling the electronic properties of the graphene. We have demonstrated with first principles calculations that the hydrogenation can be used to make separators to electrically separate zigzag graphene nanoribbons (zGNR) and tune their transport properties. First principles calculations reveal that each hydrogenation separator can introduce two conducting edge-like states into the subbands around the Fermi level, which can greatly enhance the conductance of the system. We find that the zGNRs with hydrogenation separators are still spin polarized; the distributions of spin densities are mainly located along the two edges of the pristine nanoribbon and the borders of the separators. The current polarization shows a nice oscillation behavior as a function of the position of the separator, which originates from the symmetry dependent transport character of the zGNRs. Moreover, we find that the hydrogenation separators can screen the impact of rough edges, which makes rough-edge zGNRs behave like smooth-edge zGNRs. Our findings could be very useful for designing electronic devices based on the hydrogenation of graphene nanoribbons.
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| 44. |
- Li, Yan, et al.
(author)
-
Ambulatory Hypertension Subtypes and 24-Hour Systolic and Diastolic Blood Pressure as Distinct Outcome Predictors in 8341 Untreated People Recruited From 12 Populations
- 2014
-
In: Circulation. - 0009-7322 .- 1524-4539. ; 130:6, s. 466-474
-
Journal article (peer-reviewed)abstract
- Background-Data on risk associated with 24-hour ambulatory diastolic (DBP24) versus systolic (SBP24) blood pressure are scarce. Methods and Results-We recorded 24-hour blood pressure and health outcomes in 8341 untreated people (mean age, 50.8 years; 46.6% women) randomly recruited from 12 populations. We computed hazard ratios (HRs) using multivariable-adjusted Cox regression. Over 11.2 years (median), 927 (11.1%) participants died, 356 (4.3%) from cardiovascular causes, and 744 (8.9%) experienced a fatal or nonfatal cardiovascular event. Isolated diastolic hypertension (DBP24 >= 80 mm Hg) did not increase the risk of total mortality, cardiovascular mortality, or stroke (HRs <= 1.54; P >= 0.18), but was associated with a higher risk of fatal combined with nonfatal cardiovascular, cardiac, or coronary events (HRs >= 1.75; P <= 0.0054). Isolated systolic hypertension (SBP24 >= 130 mm Hg) and mixed diastolic plus systolic hypertension were associated with increased risks of all aforementioned end points (P <= 0.0012). Below age 50, DBP24 was the main driver of risk, reaching significance for total (HR for 1-SD increase, 2.05; P=0.0039) and cardiovascular mortality (HR, 4.07; P=0.0032) and for all cardiovascular end points combined (HR, 1.74; P=0.039) with a nonsignificant contribution of SBP24 (HR <= 0.92; P >= 0.068); above age 50, SBP24 predicted all end points (HR >= 1.19; P <= 0.0002) with a nonsignificant contribution of DBP24 (0.96 <= HR <= 1.14; P >= 0.10). The interactions of age with SBP24 and DBP24 were significant for all cardiovascular and coronary events (P <= 0.043). Conclusions-The risks conferred by DBP24 and SBP24 are age dependent. DBP24 and isolated diastolic hypertension drive coronary complications below age 50, whereas above age 50 SBP24 and isolated systolic and mixed hypertension are the predominant risk factors.
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| 45. |
- Lian, Ke-Yan, et al.
(author)
-
Tuning electronic and magnetic properties of armchair vertical bar zigzag hybrid graphene nanoribbons by the choice of supercell model of grain boundaries
- 2014
-
In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 115:10, s. 104303-
-
Journal article (peer-reviewed)abstract
- Grain boundaries (GBs) attract much interest for its ability to tune the property of hybrid materials. Theoretically predicting the properties of hybrid graphene with GBs, even a linear GB remains challenging due to its inhomogeneous structure, which makes supercell model tough to choose in theoretic studies. For the first time, the applicability of supercells with different GBs and lattice-mismatches for describing armchair-zigzag hybrid graphene nanoribbons was validated by ab initio molecular dynamic simulations and first principles electronic structure calculations. And to what extent the electronic properties can be tuned by the strain effects resulting from the lattice-mismatch and the GBs distortion in supercells was demonstrated. This work showed that the intrinsic strain in such system plays a decisive role in determining the band structure and spin polarization properties. Hybrid graphene nanoribbon was found to be ferromagnetic in the ground state, especially for the case of using the supercell with nearly-perfect lattice match. Its high Curie temperature suggests the potential applications of this material in spintronics.
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| 46. |
- Liu, Dongbin, et al.
(author)
-
Intraductal papillary mucinous neoplasms of the pancreas: diagnosis and management.
- 2010
-
In: European Journal of Gastroenterology and Hepathology. - 1473-5687. ; 22:9, s. 1029-1038
-
Journal article (peer-reviewed)abstract
- Intraductal papillary mucinous neoplasms (IPMNs), characterized by intraductal papillary growth and thick mucin secretion, have increasingly been recognized. Despite modern preoperative evaluation, major difficulties still remain in distinguishing malignant invasive types from benign IPMNs. Following a PubMed database search, all relevant abstracts and articles on IPMN published in English and Chinese were reviewed. Main-duct and the mixed type IPMNs carry a higher risk of malignancy as compared with branch-duct type IPMNs. Treatment of branch-duct type IPMNs remains controversial. Once operation is indicated, intraoperative frozen section of margins plays an important role in the decision concerning the extent and type of surgery. Pancreatectomy, partly preserving both endocrine and exocrine pancreatic function, is advocated for most patients with IPMN, though total pancreatectomy may be necessary in some. Both for patients subjected to surgery and those only observed, IPMN patients need regular close follow-up to identify recurrence or progressive disease.
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| 47. |
- Niu, Shuli, et al.
(author)
-
Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms.
- 2012
-
In: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 194:3, s. 775-783
-
Journal article (peer-reviewed)abstract
- • It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. • Here, we compiled data from 169 globally distributed sites of eddy covariance and quantified the temperature response functions of net ecosystem exchange (NEE), an ecosystem-level property, to determine whether NEE shows thermal optimality and to explore the underlying mechanisms. • We found that the temperature response of NEE followed a peak curve, with the optimum temperature (corresponding to the maximum magnitude of NEE) being positively correlated with annual mean temperature over years and across sites. Shifts of the optimum temperature of NEE were mostly a result of temperature acclimation of gross primary productivity (upward shift of optimum temperature) rather than changes in the temperature sensitivity of ecosystem respiration. • Ecosystem-level thermal optimality is a newly revealed ecosystem property, presumably reflecting associated evolutionary adaptation of organisms within ecosystems, and has the potential to significantly regulate ecosystem-climate change feedbacks. The thermal optimality of NEE has implications for understanding fundamental properties of ecosystems in changing environments and benchmarking global models.
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| 48. |
- Pang, H., et al.
(author)
-
The role of oxygen in a large area of RF-powered atmospheric pressure dielectric barrier glow discharge plasma in sterilization
- 2011
-
In: IEEE Transactions on Plasma Science. - 0093-3813. ; 39:8, s. 1689-1694
-
Journal article (peer-reviewed)abstract
- A nonequilibrium Ar/O2 plasma at atmospheric pressure was generated between two parallel square electrodes by a 13.56-MHz power supplier. Experimental results demonstrate that the Ar/O2 plasma more effectively kills Staphylococcus aureus and Escherichia coli than the Ar plasma. When the O2 flow rate increases from 0 to 100 sccm step by step, the discharge voltage and the radio-frequency (RF) current always show sinusoidal waveforms, and the discharges maintain the α mode as well. In addition, the sterilization efficiency values of the RF-powered atmospheric pressure Ar/O2 plasma depend on the oxygen fraction in Ar gas. It is found that the sterilization efficiency of the Ar/O2 plasma is highest with 0.5 vol.% oxygen in argon gas, corresponding to the maximum production of O(3P) radicals. It is considered that the O(3P) radicals produced by the Ar/O2 plasma play a significant role in atmospheric plasma sterilization.
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| 49. |
- Rasch, Katharina, 1982-, et al.
(author)
-
Context-driven personalized service discovery in pervasive environments
- 2011
-
In: World wide web (Bussum). - MA, USA : Kluwer Academic Publishers Hingham. - 1386-145X .- 1573-1413. ; 14:4, s. 295-319
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Journal article (peer-reviewed)abstract
- Pervasive environments are characterized by a large number of embedded devices offering their services to the user .Which of the available services are of most interest to the user considerably depends on the user’s current context. User context is often rich and very dynamic; making an explicit, user-driven discovery of services impractical. Users in such environments would instead like to be continuously informed about services relevant to them. Implicit discovery requests triggered by changes in the context are therefore prevalent. This paper proposes a proactiveservice discovery approach for pervasive environments addressing these implicit requests. Services and user preferences are described by a formal context modelcalled Hyperspace Analogue to Context, which effectively captures the dynamics of context and the relationship between services and context. Based on the model, we propose a set of algorithms that can continuously present the most relevant services to the user in response to changes of context, services or user preferences. Numeric coding methods are applied to improve the algorithms’ performance. The algorithms are grounded in a context-driven service discovery system that automatically reacts to changes in the environment. New context sources and services can be dynamically integrated into the system. A client for smart phones continuously informs users about the discovery results. Experiments show, that the system can efficiently provide the user with continuous, up-to-date information about the most useful services in real time.
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- Wang, Guo-dong, et al.
(author)
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The genomics of selection in dogs and the parallel evolution between dogs and humans
- 2013
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In: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 4, s. 1860-
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Journal article (peer-reviewed)abstract
- The genetic bases of demographic changes and artificial selection underlying domestication are of great interest in evolutionary biology. Here we perform whole-genome sequencing of multiple grey wolves, Chinese indigenous dogs and dogs of diverse breeds. Demographic analysis show that the split between wolves and Chinese indigenous dogs occurred 32,000 years ago and that the subsequent bottlenecks were mild. Therefore, dogs may have been under human selection over a much longer time than previously concluded, based on molecular data, perhaps by initially scavenging with humans. Population genetic analysis identifies a list of genes under positive selection during domestication, which overlaps extensively with the corresponding list of positively selected genes in humans. Parallel evolution is most apparent in genes for digestion and metabolism, neurological process and cancer. Our study, for the first time, draws together humans and dogs in their recent genomic evolution.
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