Nonuniformity in Lattice Contraction of Bismuth Nanoclusters Heated Near Its Melting Point

The structural properties of bismuth nanoclusters were investigated with transmission high-energy electron diffraction from room temperature up to 525 ± 6 K. The Bi nanoclusters were fabricated by thermal evaporation at room temperature on transmission electron microscope grids coated with an ultrathin carbon film, followed by thermal and femtosecond laser annealing. The annealed sample had an average cluster size of ∼14 nm along the minor axis and ∼16 nm along the major axis. The Debye temperature of the annealed nanoclusters was found to be 53 ± 6 K along the [012] direction and 86 ± 9 K along the [110] direction. At T = 464 ± 6 K, the diffraction intensity started to deviate from Debye-Waller behavior due to increased lattice anharmonicity. The onset of the melting of the Bi nanoclusters was T ∼ 500 ± 6 K, as measured by the reduction of the nanocluster size through the formation of a liquid shell detected by the width of the diffraction rings. The thermal expansion coefficient of the Bi (012) and (110) planes is positive up to ∼ 499 11 K. However, the expansion coefficient of the Bi (012) planes showed a transition from a positive to a negative value that occurs over the temperature range Tc ∼ 499 ± 11 K to 511 ± 8 K. For the Bi (110) planes, the thermal expansion coefficient is positive up to their melting point, which is 525 ± 6 K. © 2011 American Institute of Physics. [doi:10.1063/1.3565028

Matroidal and Lattices Structures of Rough Sets and Some of Their Topological Characterizations

Matroids, rough set theory and lattices are efficient tools of knowledge discovery. Lattices and matroids are studied on preapproximations spaces. Li et al. proved that a lattice is Boolean if it is clopen set lattice for matroids. In our study, a lattice is Boolean if it is closed for matroids. Moreover, a topological lattice is discussed using its matroidal structure. Atoms in a complete atomic Boolean lattice are completely determined through its topological structure. Finally, a necessary and sufficient condition for a predefinable set is proved in preapproximation spaces. The value k for a predefinable set in lattice of matroidal closed sets is determined

Matroidal and Lattices Structures of Rough Sets and Some of Their Topological Characterizations

Matroids, rough set theory and lattices are efficient tools of knowledge discovery. Lattices and matroids are studied on preapproximations spaces. Li et al. proved that a lattice is Boolean if it is clopen set lattice for matroids. In our study, a lattice is Boolean if it is closed for matroids. Moreover, a topological lattice is discussed using its matroidal structure. Atoms in a complete atomic Boolean lattice are completely determined through its topological structure. Finally, a necessary and sufficient condition for a predefinable set is proved in preapproximation spaces. The value k for a predefinable set in lattice of matroidal closed sets is determined

Coherent Phonons in Bismuth Film Observed by Ultrafast Electron Diffraction

The generation of coherent phonons in polycrystalline bismuth film excited with femtosecond laser pulse is observed by ultrafast time-resolved electron diffraction. The dynamics of the diffracted intensities from the (110), (202), and (024) lattice planes show pronounced oscillations at 130-150 GHz. The origin of these coherent acoustic phonons is discussed in view of optical phonon decay into two acoustic phonons. Different drop times in the intensity of the diffraction orders are observed and interpreted as anisotropy in the energy transfer rate of coherent optical phonons

Potential Damages, Seasonal Abundance and Distribution of Empoasca Terminalis Distant (Homoptera: Cicadellidae) on Soybean in South Sulawesi

Plant damages caused by leafhopper, Empoasca terminalis Distant (Homoptera: Cicadellidae) on soybean were first encountered in 2007 in Makassar, South Sulawesi. The insect has been constantly associated with soybean crops in the province ever since. The purposes of the present study were to (i) evaluate potential yield loss attributable to the leafhopper in an experimental set up, (ii) seasonal abundance of E. terminalis, and (iii) distribution of E. terminalis in all major soybean-producing areas in the province. Potential yield loss due to the leafhopper was assessed in a field experiment using two large plots. One of the plots was kept leafhopper-free by weekly insecticide sprays; and the other plot was left unsprayed to allow leafhopper infestation to occur. Adult abundance was weekly monitored using a sweep net throughout the season. Nymph abundance was determined by direct count on the plant leaves. Leafhopper distribution was assessed through surveys conducted in all major soybean-producing areas in South Sulawesi, from 2009–2013. The results of the study showed that E. terminalis caused an average yield loss of 26% on susceptible crops without insecticide use. First leafhopper infestation in all planting seasons occurred two weeks after the plant emergence. Rainfall negatively correlated with the leafhopper abundance. The leafhopper existed in all major soybean production areas in the province. Therefore, our results confirmed the status of E. terminalis as an important soybean pest in the region. In addition, crops planted early in the dry season could escape from heavy leafhopper infestation

Electron refraction at lateral atomic interfaces

We present theoretical simulations of electron refraction at the lateral atomic interface between a “homogeneous” Cu(111) surface and the “nanostructured” one-monolayer (ML) Ag/Cu(111) dislocation lattice. Calculations are performed for electron binding energies barely below the 1 ML Ag/ Cu(111) M-point gap (binding energy EB ¼53 meV, below the Fermi level) and slightly above its C -point energy (EB ¼160 meV), both characterized by isotropic/circular constant energy surfaces. Using plane-wave-expansion and boundary-element methods, we show that electron refraction occurs at the interface, the Snell law is obeyed, and a total internal reflection occurs beyond the critical angle. Additionally, a weak negative refraction is observed for EB ¼53 meV electron energy at beam incidence higher than the critical angle. Such an interesting observation stems from the interface phase-matching and momentum conservation with the umklapp bands at the second Brillouin zone of the dislocation lattice. The present analysis is not restricted to our Cu-Ag/Cu model system but can be readily extended to technologically relevant interfaces with spinpolarized, highly featured, and anisotropic constant energy contours, such as those characteristic for Rashba systems and topological insulators. Published by AIP Publishing.Peer ReviewedPostprint (published version

On Sampling Distribution of Improved Estimators for Coefficients in Seemingly Unrelated Regression SUR Models

The main objective of this study is to estimate the parameters of the SUR models. A new family of biased estimators, called k-class that has the same asymptotic normal distribution as the Aitken generalized least squares (GLS) with the assumption that the covariance matrix is known. The exact bias have been studied and derived

Assessment of anti-cyclic citrullinated peptide in psoriatic arthritis

<p>Abstract</p> <p>Background</p> <p>Anti-cyclic citrullinated peptides (anti-CCP) are highly specific diagnostic and prognostic markers for rheumatoid arthritis (RA). They have been also found in psoriatic arthritis (PsA), with controversies as regards clinical and radiological associations. The current study assessed anti-CCP in PsA and determined its clinical and radiological associations.</p> <p>Methods</p> <p>Four groups contributed to this study. 40 PsA, 40 psoriasis without arthritis, 40 RA and 40 healthy controls. They were tested for anti-CCP. Clinical and radiological data were collected and statistically compared between anti-CCP-positive and -negative PsA patients.</p> <p>Results</p> <p>Seven PsA (17.5%) and 34 RA (85%) were seropositive for anti-CCP. Patients of other groups were anti-CCP-negative. Regarding anti-CCP concentrations, highly significant difference existed between different groups and between anti-CCP-positive and -negative PsA. Significantly higher numbers of involved, swollen and tender joints, deformities and functional impairment of peripheral joints and radiological changes were found in anti-CCP-positive PsA.</p> <p>Conclusion</p> <p>Anti-CCP may be found in PsA and are associated with higher number of involved, swollen and tender joints, with deformities and functional impairment of peripheral joints and with erosive arthritis.</p

Modeling soil cation exchange capacity in multiple countries

Cation exchange capacity (CEC), as an important indicator for soil quality, represents soil's ability to hold positively charged ions. We attempted to predict CEC using different statistical methods including monotone analysis of variance (MONANOVA), artificial neural networks (ANNs), principal components regressions (PCR), and particle swarm optimization (PSO) in order to compare the utility of these approaches and identify the best predictor. We analyzed 170 soil samples from four different nations (USA, Spain, Iran and Iraq) under three land uses (agriculture, pasture, and forest). Seventy percent of the samples (120 samples) were selected as the calibration set and the remaining 50 samples (30%) were used as the prediction set. The results indicated that the MONANOVA (R2 =0.82 and Root Mean Squared Error (RMSE) =6.32) and ANNs (R2 = 0.82 and RMSE =5.53) were the best models to estimate CEC, PSO (R2 =0.80 and RMSE =5.54) and PCR (R2 =0.70 and RMSE =6.48) also worked well and the results were very similar to each other. While the most influential variables for the various countries and land uses were different and CEC was affected by different variables in different situations, clay (positively correlated) and sand (negatively correlated) were the most influential variables for predicting CEC for the entire data set. Although the MANOVA and ANNs provided good predictions of the entire dataset, PSO gives a formula to estimate soil CEC using commonly tested soil properties. Therefore, PSO shows promise as a technique to estimate soil CEC. Establishing effective pedotransfer functions to predict CEC would be productive where there are limitations of time and money, and other commonly analyzed soil properties are available