Theoretical backgrounds of nonlinear THz spectroscopy of semiconductor superlattices

We consider terahertz absorption and gain in a single miniband of semiconductor superlattice subject to a bichromatic electric field in the most general case of commensurate frequencies of the probe and pump fields. Using an exact solution of Boltzmann transport equation, we show that in the small-signal limit the formulas for absorption always contain two distinct terms related to the parametric and incoherent interactions of miniband electrons with the alternating pump field. It provides a theoretical background for a control of THz gain without switching to the negative differential conductivity state. For pedagogical reasons we present derivations of formulas in detail.Comment: 14 page

Sol-Gel Synthesis, X-Ray Diffraction Studies and Electric Conductivity of Sodium Europium Silicate

Sodium europium silicate, NaEu9(SiO4)6O2, with apatite structure has been obtained and studied using X-ray diffraction and SEM. It has been shown that sodium sublimation does not take place upon synthesis by the sol-gel method. Rietveld refinement has revealed that sodium atoms are ordered and occupy the 4f position. O(4) atoms not related to silicate ions are placed at the centers of Eu(2) triangles. DC and AC electric conductivity and activation energy have been determined for the compound studied

Sol-Gel Synthesis, X-Ray Diffraction Studies and Electric Conductivity of Sodium Europium Silicate

Sodium europium silicate, NaEu9(SiO4)6O2, with apatite structure has been obtained and studied using X-ray diffraction and SEM. It has been shown that sodium sublimation does not take place upon synthesis by the sol-gel method. Rietveld refinement has revealed that sodium atoms are ordered and occupy the 4f position. O(4) atoms not related to silicate ions are placed at the centers of Eu(2) triangles. DC and AC electric conductivity and activation energy have been determined for the compound studied

Chiral light in twisted Fabry-P\'erot cavities

Fundamental studies of the interaction of chiral light with chiral matter are important for the development of techniques that allow handedness-selective optical detection of chiral organic molecules. One approach to achieve this goal is the creation of a Fabry-P\'erot cavity that supports eigenmodes with a desired electromagnetic handedness, which interacts differently with left and right molecular enantiomers. In this paper, we theoretically study chiral Fabry-P\'erot cavities with mirrors comprising one-dimensional photonic crystal slabs made of van der Waals As$_2$S$_3$, a material with one of the highest known in-plane anisotropy. By utilizing the anisotropy degree of freedom provided by As$_2$S$_3$, we design Fabry-P\'erot cavities with constitutional and configurational geometrical chiralities. We demonstrate that in cavities with constitutional chirality, electromagnetic modes of left or right handedness exist due to the chirality of both mirrors, often referred to as handedness preserving mirrors in the literature. At the same time, cavities with configurational chirality support modes of both handednesses due to chiral morphology of the entire structure, set by the twist angle between the optical axes of the upper and lower non-chiral anisotropic mirrors. The developed chiral Fabry-P\'erot cavities can be tuned to the technologically available distance between the mirrors by properly twisting them, making such systems a prospective platform for the coupling of chiral light with chiral matter.Comment: 33 pages, 9 figure

Synthesis, Crystal Structure Refinement, and Electrical Conductivity of Pb(8−x)Na2Smx(VO4)6O(x/2)

Solid solutions of Pb(8−x)Na2Smx(VO4)6O(x/2) were studied using X-ray diffraction analysis including Rietveld refinement and scanning electron microscopy and by measuring their electrical conductivity. Crystal structure of the solid solutions was refined and the solubility region 0 ≤ x ≤ 0.2 was determined for samarium substitution for lead under the scheme 2Pb2+ + ◻ → 2Sm3+ + O2-. The influence of degree of substitution on the electrical conductivity of solid solutions was established

Sol-Gel Synthesis, X-Ray Diffraction Studies, and Electric Conductivity of Sodium Europium Silicate

Sodium europium silicate, NaEu9(SiO4)6O2, with apatite structure has been obtained and studied using X-ray diffraction and SEM. It has been shown that sodium sublimation does not take place upon synthesis by the sol-gel method. Rietveld refinement has revealed that sodium atoms are ordered and occupy the 4f position. O(4) atoms not related to silicate ions are placed at the centers of Eu(2) triangles. DC and AC electric conductivity and activation energy have been determined for the compound studied

The 203 kbp Mitochondrial Genome of the Phytopathogenic Fungus <i>Sclerotinia borealis</i> Reveals Multiple Invasions of Introns and Genomic Duplications

<div><p>Here we report the complete sequence of the mitochondrial (mt) genome of the necrotrophic phytopathogenic fungus <i>Sclerotinia borealis</i>, a member of the order <i>Helotiales</i> of Ascomycetes. The 203,051 bp long mtDNA of <i>S. borealis</i> represents one of the largest sequenced fungal mt genomes. The large size is mostly determined by the presence of mobile genetic elements, which include 61 introns. Introns contain a total of 125,394 bp, are scattered throughout the genome, and are found in 12 protein-coding genes and in the ribosomal RNA genes. Most introns contain complete or truncated ORFs that are related to homing endonucleases of the LAGLIDADG and GIY-YIG families. Integrations of mobile elements are also evidenced by the presence of two regions similar to fragments of inverton-like plasmids. Although duplications of some short genome regions, resulting in the appearance of truncated extra copies of genes, did occur, we found no evidences of extensive accumulation of repeat sequences accounting for mitochondrial genome size expansion in some other fungi. Comparisons of mtDNA of <i>S. borealis</i> with other members of the order <i>Helotiales</i> reveal considerable gene order conservation and a dynamic pattern of intron acquisition and loss during evolution. Our data are consistent with the hypothesis that horizontal DNA transfer has played a significant role in the evolution and size expansion of the <i>S. borealis</i> mt genome.</p></div

Genes encoding 14 typical mitochondrial proteins and the ribosomal RNA subunits in <i>S. borealis</i> mitochondrial genome.

<p>Genes encoding 14 typical mitochondrial proteins and the ribosomal RNA subunits in <i>S. borealis</i> mitochondrial genome.</p

The phylogenetic tree was calculated from the multiple sequence alignment of concatenated mtDNA-encoded proteins of 51 fungal species.

<p>A dataset of 14 proteins was used, and topology was inferred using Bayesian method. Numbers above the nodes indicate bootstrap support values. The tree is drawn to scale, with branch lengths measured by the number of substitutions per site. Species analysed are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107536#pone.0107536.s005" target="_blank">Table S3</a>; only the <i>Ascomycota</i> branch of the whole tree is shown.</p

Structure of the <i>S. borealis cox1</i> gene introns 1 (A) and 8 (B).

<p>Introns are represented by black horizontal bars; the sizes are drawn to scale. Red arrows show HEG-like ORFs. Green and blue rectangles show, respectively, catalytic GIY-YIG_bI1_like (cd10445) and LAGLIDADG_1 (pfam00961) domains. Nucleotide sequence similarity is indicated by grey areas between introns. Sbor – <i>S. borealis</i>, Bfuc – <i>B. fuckeliana</i>, Pmal – <i>P. malacea</i>, Pans – <i>P. anserina</i>.</p