63 research outputs found

    Competitions of magnetism and superconductivity in FeAs-based materials

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    Using the numerical unrestricted Hartree-Fock approach, we study the ground state of a two-orbital model describing newly discovered FeAs-based superconductors. We observe the competition of a (0,π)(0, \pi) mode spin-density wave and the superconductivity as the doping concentration changes. There might be a small region in the electron-doping side where the magnetism and superconductivity coexist. The superconducting pairing is found to be spin singlet, orbital even, and mixed sxy_{xy} + dx2y2_{x^{2}-y^{2}} wave (even parity).Comment: 5 pages, 3 figure

    Mechanistic aspects of photo-induced formation of peroxide ions on the surface of cubic Ln(2)O(3) (Ln = Nd, Sm, Gd) under oxygen

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    National Basic Research Program of China [2010CB732303]; National Natural Science Foundation of China [21173173, 21033006, 20923004]; Program for Changjiang Scholars and Innovative Research Team in University [IRT1036]The photo-induced formation of peroxide ions on the surface of cubic Ln(2)O(3) (Ln = Nd, Sm, Gd) was studied by in situ microprobe Raman spectroscopy using a 325 nm laser as excitation source. It was found that the Raman bands of peroxide ions at 833-843 cm(-1) began to grow at the expense of the Ln(3+)-O-2 bands at 333-359 cm(-1) when the Ln(2)O(3) samples under O-2 were continuously irradiated with a focused 325 nm laser beam at temperatures between 25-150 degrees C. The intensity of the peroxide Raman band was found to increase with increasing O-2 partial pressure, whereas no peroxide band was detected on the Ln(2)O(3) under N-2 as well as on the samples first irradiated with laser under Ar or N-2 followed by exposure to O-2 in the dark. The experiments using O-18 as a tracer further confirmed that the peroxide ions are generated by a photo-induced reaction between O-2 and the lattice oxygen (O2-) species in Ln(2)O(3). Under the excitation of 325 nm UV light, the transformation of O-2 to peroxide ions on the surface of the above lanthanide sesquioxides can even take place at room temperature. Basicity of the lattice oxygen species on Ln(2)O(3) also has an impact on the peroxide formation. Higher temperature or laser irradiation power is required to initiate the reaction between O-2 and O2- species of weaker basicity

    Finishing the euchromatic sequence of the human genome

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    The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

    Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

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    Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

    Optimization of Wireless Sensor Networks Based on Differential Evolution Algorithm

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    To study the optimization problem of wireless sensor network (WSN) based on differential evolution, the single objective differential evolution algorithm is applied and combined with the advantages and disadvantages crossover strategy. Firstly, the path optimization problem in WSN is analyzed, and the optimization model is established. Then, the differential evolution algorithm is used as the search tool to solve the minimum energy consumption in the path optimization model, that is, the optimal path problem. Finally, the comparison experiment is carried out on the classical algorithm genetic algorithm (GA), particle swarm optimization (PSO) and standard differential evolution (DE) algorithm. The results show that the performance of differential evolution algorithm based on crossover strategy is superior to or not worse than that of several contrast algorithms. It can be seen that the differential evolution algorithm based on advantage and disadvantage crossover strategy has good effectiveness

    Optimization of Wireless Sensor Networks Based on Differential Evolution Algorithm

    No full text
    To study the optimization problem of wireless sensor network (WSN) based on differential evolution, the single objective differential evolution algorithm is applied and combined with the advantages and disadvantages crossover strategy. Firstly, the path optimization problem in WSN is analyzed, and the optimization model is established. Then, the differential evolution algorithm is used as the search tool to solve the minimum energy consumption in the path optimization model, that is, the optimal path problem. Finally, the comparison experiment is carried out on the classical algorithm genetic algorithm (GA), particle swarm optimization (PSO) and standard differential evolution (DE) algorithm. The results show that the performance of differential evolution algorithm based on crossover strategy is superior to or not worse than that of several contrast algorithms. It can be seen that the differential evolution algorithm based on advantage and disadvantage crossover strategy has good effectiveness

    Sinter-Resistant Pd/SiO2 Nanocatalyst Prepared by Impregnation Method

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    National Basic Research Program of China [2010CB732303]; National Natural Science Foundation of China [20873111, 20923004, 21033006]; Key Scientific Project of Fujian Province, China [2009HZ0002-1
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