Electron energy-loss spectroscopy and ab initio electronic structure of the LaOFeP superconductor

The electronic band structures of the LaOFeP superconductor have been calculated theoretically by the first principles method and measured experimentally by electron energy loss spectroscopy. The calculations indicate that the Fe atom in LaOFeP crystal shows a weak magnetic moment and does not form a long-range magnetic ordering. Band structure, Fermi surfaces and fluorine-doping effects are also analyzed based on the data of the density functional theory. The fine structures of the EELS data have been carefully examined in both the low loss energy region and the core losses region (O K, Fe L2,3, and La M4,5). A slight bump edge at 44 eV shows notable orientation-dependence: it can be observed in the low loss EELS spectra with q parallel to c, but becomes almost invisible in the q vertical to c spectra. Annealing experiments indicate that low oxygen pressure favors the appearance of superconductivity in LaOFeP, this fact is also confirmed by the changes of Fe L2,3 and O K excitation edges in the experimental EELS data

The intercalation of 1,10-phenanthroline into layered NiPS3 via iron dopant seeding

Using 2% percent of iron dopants as reaction active sites yields a series of single crystals of 1,10-phenanthroline intercalated NiPS3, via solution reaction with aniline chloride, not possible by direct reaction. Experimental magnetic susceptibility measurements demonstrate that 1,10-phenanthroline intercalation suppresses the anti-ferromagnetism ordering at around 150 K in Fe0.02Ni0.98PS3, and gives rise to a ferrimagnetic phase transition at the temperature around 75 K. A intercalation mechanism is proposed for the reaction, and this dopant seeding method provides a new approach for intercalation into layered materials

Whole-genome sequencing of <em>Oryza brachyantha</em> reveals mechanisms underlying <em>Oryza</em> genome evolution

The wild species of the genus Oryza contain a largely untapped reservoir of agronomically important genes for rice improvement. Here we report the 261-Mb de novo assembled genome sequence of Oryza brachyantha. Low activity of long-terminal repeat retrotransposons and massive internal deletions of ancient long-terminal repeat elements lead to the compact genome of Oryza brachyantha. We model 32,038 protein-coding genes in the Oryza brachyantha genome, of which only 70% are located in collinear positions in comparison with the rice genome. Analysing breakpoints of non-collinear genes suggests that double-strand break repair through non-homologous end joining has an important role in gene movement and erosion of collinearity in the Oryza genomes. Transition of euchromatin to heterochromatin in the rice genome is accompanied by segmental and tandem duplications, further expanded by transposable element insertions. The high-quality reference genome sequence of Oryza brachyantha provides an important resource for functional and evolutionary studies in the genus Oryza

CBED Tools for semi-automatic measurement of crystal thicknesses

Convergent-beam electron diffraction (CBED) is one of the most popular techniques to measure crystal thickness. The traditional measurement involves linear fitting of several fringes across the CBED disc, but for a thin crystal with fewer than three fringes the usefulness of this method will be limited. CBED Tools, a free plugin for the DigitalMicrograph software, provides a fast (similar to 12 min) and accurate algorithm to measure the crystal thickness on the basis of the linear fitting method, but it is also capable of determining the crystal thickness when it is very thin and only one fringe or part of the first fringe is recorded. CBED Tools can also be utilized to handle the severely distorted CBED pattern obtained when the zero-order Laue zone Kikuchi lines overlap with the fringes.</p

MICROSCOPY RESEARCH AND TECHNIQUE

 We report a quick and easy method for a random selected area electron diffraction (SAED) pattern without rotating and tilting the specimen to perform phase identification and unit cell determination by combined with the XRD softwares. If your TEM is well aligned and camera length is carefully corrected, two-dimensional (2D)-SAED pattern can be directly transformed to 1D-profile after the center determination of pattern, this profile is then imported to XRD analysis packages. Finally, phase identification and unit cell determination can be performed after peak search or precise peak position determined by profile fitting. Two examples, flaky-like TiO2 nanomaterial and TiO2 nanotubes precipitated by the silver nanoparticles, were tested and verified for the validation of phase identification and unit cell determination using this method; the successful crystallographic analysis of one single gold nanocrystal indicates it is still validate for the nanocrystals with the smaller diffraction volume, but need two or more random tilt SAED patterns. This method could be further used in the quantitative phase analysis, structure determination and Rietveld refinement for the nanomaterials if the reliable integrated intensity can be extracted. Microsc. Res. Tech. 76:641647, 2013. (c) 2013 Wiley Periodicals, Inc.</span

A method for structure analysis of nanomaterials by electron diffraction: Phase identification and unit cell determination

We report a quick and easy method for a random selected area electron diffraction (SAED) pattern without rotating and tilting the specimen to perform phase identification and unit cell determination by combined with the XRD softwares. If your TEM is well aligned and camera length is carefully corrected, two-dimensional (2D)-SAED pattern can be directly transformed to 1D-profile after the center determination of pattern, this profile is then imported to XRD analysis packages. Finally, phase identification and unit cell determination can be performed after peak search or precise peak position determined by profile fitting. Two examples, flaky-like TiO2 nanomaterial and TiO2 nanotubes precipitated by the silver nanoparticles, were tested and verified for the validation of phase identification and unit cell determination using this method; the successful crystallographic analysis of one single gold nanocrystal indicates it is still validate for the nanocrystals with the smaller diffraction volume, but need two or more random tilt SAED patterns. This method could be further used in the quantitative phase analysis, structure determination and Rietveld refinement for the nanomaterials if the reliable integrated intensity can be extracted. Microsc. Res. Tech. 76:641647, 2013. (c) 2013 Wiley Periodicals, Inc

SACT: A New Model of Covert Communication Based on SDN

Anonymous tracking technology of network watermarking is limited by the deployment of tracking devices in traditional network structure, resulting in poor scalability and reusability. Software Defined Network (SDN) boasts more freedom thanks to its separation of the control plane from the data plane. In this paper, a new anonymous communication tracking model SDN-based Anonymous Communication Tracking (SACT) is proposed, which introduces network watermarking into SDN and combines IP time hidden channel and symbol expansion technology. In addition, we introduce a hopping protection mechanism to improve the anti detection ability of the watermark as well. The experimental results show that in a variety of simulated network environments, SACT achieves excellent detection rate and bit error rate, thus it is sufficient to determine the communication relationship between the two parties. Meanwhile, SACT solves the deployment problem of anonymous tracking and improves the availability and scalability of covert communication