Widely Tunable Distributed Bragg Reflectors Integrated into Nanowire Waveguides

Periodic structures with dimensions on the order of the wavelength of light can tailor and improve the performance of optical components, and they can enable the creation of devices with new functionalities. For example, distributed Bragg reflectors (DBRs), which are created by periodic modulations in a structure’s dielectric medium, are essential in dielectric mirrors, vertical cavity surface emitting lasers, fiber Bragg gratings, and single-frequency laser diodes. This work introduces nanoscale DBRs integrated directly into gallium nitride (GaN) nanowire waveguides. Photonic band gaps that are tunable across the visible spectrum are demonstrated by precisely controlling the grating’s parameters. Numerical simulations indicate that in-wire DBRs have significantly larger reflection coefficients in comparison with the nanowire’s end facet. By comparing the measured spectra with the simulated spectra, the index of refraction of the GaN nanowire waveguides was extracted to facilitate the design of photonic coupling structures that are sensitive to phase-matching conditions. This work indicates the potential to design nanowire-based devices with improved performance for optical resonators and optical routing

Complex Formation Between Lysozyme and Stabilized Micelles with a Mixed Poly(ethylene oxide)/Poly(acrylic acid) Shell

The electrostatic complexation between lysozyme and stabilized polymeric micelles (SPMs) with a poly­(acrylic acid) (PAA) or a mixed poly­(ethylene oxide)/poly­(acrylic acid) (PEO/PAA) shell (SPMs with a mixed shell, SPMMS) and a temperature-responsive poly­(propylene oxide) (PPO) core was investigated by means of dynamic, static, and electrophoretic light scattering. The SPMs and different types of SPMMS used resulted from the self-assembly of PAA–PPO–PAA triblock copolymer chains, or PAA–PPO–PAA and PEO–PPO–PEO triblock copolymer chain mixtures (with varying chain lengths and molar ratios) in aqueous solutions at pH 10 and the subsequent cross-linking of their PPO cores via loading and photo-cross-linking of pentaerythritol tetraacrylate (PETA). The solution behavior, structure and properties of the formed complexes at pH 7 and 0.01 M ionic strength, were studied as a function of the protein concentration in the solution (the concentration of the stabilized micelles was kept constant) or equivalently the ratio of the two components. The complexation process and properties of the complexes proved to be dependent on the protein concentration, while of particular interest was the effect of the structure of the shell of the SPMs on the stability/solubility of the complexes. Finally, the fluorescence and mid infrared spectroscopic investigation of the structure of the complexed protein showed that, although a small stretching of the protein molecules occurred in some cases, no protein denaturation takes place upon complexation

Trojan family genes in avian and non-avian species.

<p>Gene names combine the respective homologue: Mystran (MYS), Trojan (TRO), Thracian (THR), Protein phosphatase (PP) or Transmembrane protein (TP) and the species abbreviation. Avian species: <i>A</i>. <i>platyrhynchos</i> (ANAPL), <i>C</i>. <i>brachyrhynchos</i> (CORBR), <i>C</i>. <i>canorus</i> (CUCCA), <i>F</i>. <i>peregrinus</i> (FALPE), <i>F</i>. <i>albicollis</i> (FICAL), <i>G</i>. <i>fortis</i> (GEOFO), <i>M</i>. <i>gallopavo</i> (MELGA), <i>M</i>. <i>undulatus</i> (MELUN), <i>O</i>. <i>hoazin</i> (OPPHO), <i>T</i>. <i>guttata</i> (TAEGU); Non-avian species: <i>A</i>. <i>carolinensis</i> (ANOCA), <i>C</i>. <i>mydas</i> (CHEMY), <i>C</i>. <i>picta</i> (CHRPI), <i>L</i>. <i>chalumnae</i> (LATCH). An arrow indicates a gene found on more than one scaffold and the direction the scaffolds were combined.</p><p>Trojan family genes in avian and non-avian species.</p

The Trojan family in chicken.

<p>A) <i>Mystran</i>, <i>Trojan</i> and <i>Thracian</i> on chicken chromosome Z. Genes are represented as hollow boxes showing their direction. Exons are shown as filled fragments within the gene boxes; B) The overall topology organization of the Trojan family proteins. Complement control protein (CCP) domains, fibronectin type III domains (FN3) and protein tyrosine phosphatase domains (PTP) are labeled. Signal peptides (SP), domains, transmembrane regions (TM), N-glycosylation (N-glyc) sites and intrinsically disordered (ID) binding sites are indicated. The Mystran CCP domain is shown in gray scale, as it was predicted slightly below threshold, but had the expected position. C) The cytoplasmic tails of Mystran, Trojan and Thracian are shown in a “snake” amino acids view. Short functional motifs are indicated: MAPK docking motif (DOC_MAPK), Grb association motif (LIG_SH_GRB), 14-3-3 docking motif (LIG_14-3-3), PKA phosphorylation motif (MOD_PKA), ITAM (LIG_TYR_ITAM) and TRAF2 interacting motif (LIG_TRAF2). For Thracian, the positions of cytoplasmic sites identified to be under positive evolutionary selection with probability higher than 90% and 95% (*) are indicated.</p

Expression of chicken Mystran, Trojan and Thracian.

<p>The relative expression levels of <i>Mystran</i>, <i>Trojan</i> and <i>Thracian</i> genes are presented as RNASeq reads from different organs, tissues, or cell types. Data from Ensembl 75.</p

Gene conversion analyzes for the Trojan family in avian species.

<p>The gene converted fragments between sequence pairs (Sequence I and Sequence II) are given with respect to their unaligned offsets and lengths within each sequence. “BC KA P-values”: Bonferroni-corrected KA (BLAST-like P-values). Names combine Mystran (MYS), Trojan (TRO) or Thracian (THR) and the corresponding species abbreviation. Species: <i>A</i>. <i>platyrhynchos</i> (ANAPL), <i>C</i>. <i>brachyrhynchos</i> (CORBR), <i>C</i>. <i>canorus</i> (CUCCA), <i>G</i>. <i>gallus</i> (GALGA), <i>G</i>. <i>fortis</i> (GEOFO), <i>O</i>. <i>hoazin</i> (OPPHO).</p><p>Gene conversion analyzes for the Trojan family in avian species.</p

Positively selected sites in the Trojan gene family.

<p>Amino acids from chicken Mystran, Trojan and Thracian with Bayesian posterior probabilities to belong to site-class under positive selection are listed. Probability: >90%, >95% (*) or >99%(**), as inferred by Bayes-Empirical-Bayes (BEB).</p><p>Positively selected sites in the Trojan gene family.</p

Evolutionary selection of the Trojan family members in chicken.

<p>Amino acid postmean ω values are mapped onto the protein topologies. Non selected sites are shown in blue, selected sites with probability below 90% are shown in light blue and selected sites with probability greater than 90% are shown in orange. Sites with probability greater than 95% and 99% are indicated by one or two red dots, respectively. Domain types and other topology properties are shown in the legend. The Mystran CCP domain is shown in gray scale, as it was predicted slightly below threshold, but had the expected position.</p

Trojan family proteins in other avian and non-avian species.

<p>Domain types, other topology properties and short functional motifs are shown in the legend. Domains presented in gray were predicted below threshold, but had the expected type, position and relative size. A) Avian species. B) Non-avian species.</p

ML tree of the Trojan family members from all species.

<p>Mystrans are shown in blue, Trojans are shown in green and Thracians are shown in red. Major groups of homologues are enclosed within gray boxes. The tree is rooted to <i>L</i>. <i>chalumnae</i> and bootstrap values are indicated at nodes. Gene names combine the respective orthologue: Mystran (MYS), Trojan (TRO), Thracian (THR), Protein phosphatase (PP) or Transmembrane protein (TP) and species abbreviations. Avian species: <i>A</i>. <i>platyrhynchos</i> (ANAPL), <i>C</i>. <i>brachyrhynchos</i> (CORBR), <i>C</i>. <i>canorus</i> (CUCCA), <i>F</i>. <i>peregrinus</i> (FALPE), <i>F</i>. <i>albicollis</i> (FICAL), <i>G</i>. <i>fortis</i> (GEOFO), <i>M</i>. <i>gallopavo</i> (MELGA), <i>M</i>. <i>undulatus</i> (MELUN), <i>O</i>. <i>hoazin</i> (OPPHO), <i>T</i>. <i>guttata</i> (TAEGU); Non-avian species: <i>A</i>. <i>carolinensis</i> (ANOCA), <i>C</i>. <i>mydas</i> (CHEMY), <i>C</i>. <i>picta</i> (CHRPI), <i>L</i>. <i>chalumnae</i> (LATCH).</p