Highly Stable Luminous "snakes" from CsPbX3 Perovskite Nanocrystals Anchored on Amine-Coated Silica Nanowires

CsPbX3 (X = Cl, Br, and I) perovskite nanocrystals (NCs) are known for their exceptional optoelectronic properties, yet the material's instability toward polar solvents, heat, or UV irradiation greatly limits its further applications. Herein, an efficient in situ growing strategy has been developed to give highly stable perovskite NC composites (abbreviated CsPbX3@CA-SiO2) by anchoring CsPbX3 NCs onto silica nanowires (NWs), which effectively depresses the optical degradation of their photoluminescence (PL) and enhances stability. The preparation of surface-functionalized serpentine silica NWs is realized by a sol-gel process involving hydrolysis of a mixture of tetraethyl orthosilicate (TEOS), 3-aminopropyltriethoxysilane (APTES), and trimethoxy(octadecyl)silane (TMODS) in a water/oil emulsion. The serpentine NWs are formed via an anisotropic growth with lengths up to 8 μm. The free amino groups are employed as surface ligands for growing perovskite NCs, yielding distributed monodisperse NCs (∼8 nm) around the NW matrix. The emission wavelength is tunable by simple variation of the halide compositions (CsPbX3, X = Cl, Br, or I), and the composites demonstrate a high photoluminescence quantum yield (PLQY 32-69%). Additionally, we have demonstrated the composites CsPbX3@CA-SiO2 can be self-woven to form a porous 3D hierarchical NWs membrane, giving rise to a superhydrophobic surface with hierarchical micro/nano structural features. The resulting composites exhibit high stability toward water, heat, and UV irradiation. This work elucidates an effective strategy to incorporate perovskite nanocrystals onto functional matrices as multifunctional stable light sources

Orthonectids Are Highly Degenerate Annelid Worms

The animal groups of Orthonectida and Dicyemida are tiny, extremely simple, vermiform endoparasites of various marine animals and have been linked in the Mesozoa (Figure 1). The Orthonectida (Figures 1A and 1B) have a few hundred cells, including a nervous system of just ten cells, and the Dicyemida (Figure 1C) are even simpler, with ∼40 cells. They are classic “Problematica”—the name Mesozoa suggests an evolutionary position intermediate between Protozoa and Metazoa (animals) and implies that their simplicity is a primitive state, but molecular data have shown they are members of Lophotrochozoa within Bilateria, which means that they derive from a more complex ancestor. Their precise affinities remain uncertain, however, and it is disputed whether they even constitute a clade. Ascertaining their affinities is complicated by the very fast evolution observed in their genes, potentially leading to the common systematic error of long-branch attraction (LBA). Here, we use mitochondrial and nuclear gene sequence data and show that both dicyemids and orthonectids are members of the Lophotrochozoa. Carefully addressing the effects of unequal rates of evolution, we show that the Mesozoa is polyphyletic. While the precise position of dicyemids remains unresolved within Lophotrochozoa, we identify orthonectids as members of the phylum Annelida. This result reveals one of the most extreme cases of body-plan simplification in the animal kingdom; our finding makes sense of an annelid-like cuticle in orthonectids and suggests that the circular muscle cells repeated along their body may be segmental in origin

The electronic structure of Be and BeO: Benchmark EMS measurements and LCAO calculations

The electronic band structures of Be and BeO have been measured by transmission electron momentum spectroscopy (EMS). The low atomic number of beryllium and the use of ultrathin solid films in these experiments reduce the probability of electron multiple scattering within the sample, resulting in very clean 'benchmark' measurements for the EMS technique. Experimental data are compared to tight-binding (LCAO) electronic structure calculations using Hartree-Fock, and local density (LDA-VWN), gradient corrected (PBE) and hybrid (PBE0) density functional theory. Overall, DFT calculations reproduce the EMS data for metallic Be reasonably well. PBE predictions for the valence bandwidth of Be are in excellent agreement with EMS data, provided the calculations employ a large basis set augmented with diffuse functions. For BeO, PBE calculations using a moderately sized basis set are in reasonable agreement with experiment, slightly underestimating the valence bandgap and overestimating the O(2s) and O(2p) bandwidths. The calculations also underestimate the EMS intensity of the O(2p) band around the Γ-point. Simulation of the effects of multiple scattering in the calculated oxide bandstructures do not explain these systematic differences. Crown Copyright © 2002 Published by Elsevier Science Ltd. All rights reserved

Nitrogen supplements effect on amylase production by Aspergillus niger using cassava whey medium

The production of amylase by Aspergillus niger on three cassava whey media in liquid shake culture was compared. The supplemented cassava whey (SCW) medium exhibited gave amylase activity of 495 U/ml. Biomass cropped was 1.63 g/l in the SCW medium. Yeast extract employed as a nitrogensupplement increased biomass yield of A. niger to 2.75 g/l with maximum amylase activity of 643 U/ml. Sodium nitrate (NaNO3) as nitrogen supplement had the lowest biomass yield of 0.77 g/l and amylase activity of 206 U/ml. Thus yeast extract as nitrogen supplement of cassava whey medium supported maximum production of amylase and biomass of A. niger

The mitochondrial genomes of the acoelomorph worms Paratomella rubra, Isodiametra pulchra and Archaphanostoma ylvae

Acoels are small, ubiquitous - but understudied - marine worms with a very simple body plan. Their internal phylogeny is still not fully resolved, and the position of their proposed phylum Xenacoelomorpha remains debated. Here we describe mitochondrial genome sequences from the acoels Paratomella rubra and Isodiametra pulchra, and the complete mitochondrial genome of the acoel Archaphanostoma ylvae. The P. rubra and A. ylvae sequences are typical for metazoans in size and gene content. The larger I. pulchra  mitochondrial genome contains both ribosomal genes, 21 tRNAs, but only 11 protein-coding genes. We find evidence suggesting a duplicated sequence in the I. pulchra mitochondrial genome. The P. rubra, I. pulchra and A. ylvae mitochondria have a unique genome organisation in comparison to other metazoan mitochondrial genomes. We found a large degree of protein-coding gene and tRNA overlap with little non-coding sequence in the compact P. rubra genome. Conversely, the A. ylvae and I. pulchra genomes have many long non-coding sequences between genes, likely driving genome size expansion in the latter. Phylogenetic trees inferred from mitochondrial genes retrieve Xenacoelomorpha as an early branching taxon in the deuterostomes. Sequence divergence analysis between P. rubra sampled in England and Spain indicates cryptic diversity

Accumulation-mode aerosol number concentrations in the Arctic during the ARCTAS aircraft campaign: Long-range transport of polluted and clean air from the Asian continent

We evaluate the impact of transport from midlatitudes on aerosol number concentrations in the accumulation mode (light-scattering particles (LSP) with diameters >180 nm) in the Arctic during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. We focus on transport from the Asian continent. We find marked contrasts in the number concentration (NLSP), transport efficiency (TE N-LSP, the fraction transported from sources to the Arctic), size distribution, and the chemical composition of aerosols between air parcels from anthropogenic sources in East Asia (Asian AN) and biomass burning sources in Russia and Kazakhstan (Russian BB). Asian AN air had lower NLSP and TEN-LSP (25 cm-3 and 18% in spring and 6.2 cm-3 and 3.0% in summer) than Russian BB air (280 cm-3 and 97% in spring and 36 cm-3 and 7.6% in summer) due to more efficient wet scavenging during transport from East Asia. Russian BB in this spring is the most important source of accumulation-mode aerosols over the Arctic, and BB emissions are found to be the primary source of aerosols within all the data in spring during ARCTAS. On the other hand, the contribution of Asian AN transport had a negligible effect on the accumulation-mode aerosol number concentration in the Arctic during ARCTAS. Compared with background air, NLSP was 2.3-4.7 times greater for Russian BB air but 2.4-2.6 times less for Asian AN air in both spring and summer. This result shows that the transport of Asian AN air decreases aerosol number concentrations in the Arctic, despite the large emissions of aerosols in East Asia. The very low aerosol number concentrations in Asian AN air were caused by wet removal during vertical transport in association with warm conveyor belts (WCBs). Therefore, this cleansing effect will be prominent for air transported via WCBs from other midlatitude regions and seasons. The inflow of clean midlatitude air can potentially have an important impact on accumulation-mode aerosol number concentrations in the Arctic. Copyright 2011 by the American Geophysical Union

Atomic and Molecular Interstellar Absorption Lines toward the High Galactic Latitude Stars HD 141569 and HD 157841 at Ultra-High Resolution

We present ultra-high-resolution (0.32 km s-1) spectra obtained with the 3.9 m Anglo-Australian Telescope (AAT) and Ultra-High-Resolution Facility (UHRF) of interstellar Na I D1, Na I D2, Ca II K, K I, and CH absorption toward two high Galactic latitude stars HD 141569 and HD 157841. We have compared our data with 21 cm observations obtained from the Leiden/Dwingeloo H I survey. We derive the velocity structure and column densities of the clouds represented by the various components and identify the clouds with ISM structures seen in the region at other wavelengths. We further derive abundances, linear depletions, and H2 fractional abundances for these clouds wherever possible. Both stars are located in regions of IRAS 100 μm emission associated with high Galactic latitude molecular clouds (HLCs): HD 141569 lies, in projection, close to MBM 37 and the Lynds dark cloud L134N, whereas HD 157841 is in the vicinity of the MBM 151. Toward HD 141569 we detect two components in our UHRF spectra: a weak, broad b = 4.5 km s-1 component at -15 km s-1, seen only in Ca II K absorption, and another component at 0 km s-1, seen in Na I D1, Na I D2, Ca II K, K I, and CH absorption. The cloud represented by the -15 km s-1 component is warm and may be located in a region close to the star. The cloud represented by the 0 km s-1 component has a Ca linear depletion δ(Ca) = 1.4 × 10-4 and shows evidence for the presence of dust, consistent with strong 100 μm emission seen in this region. The H2 fractional abundance f(H2) derived for this cloud is 0.4, which is typically what is observed toward HLCs. We conclude that this 0 km s-1 cloud is associated with MBM 37 and L134N based on the presence of dust and molecular gas (CH) and good velocity agreement with CO emission from these two clouds. This places HD 141569 beyond MBM 37 and L134N, which are estimated to be at ≈ 110 pc. In the case of the HD 157841 sight line, a total of six components are seen on our UHRF spectra in Na I D1, Na I D2, Ca II K, K I, and CH absorption. Two of these six components are seen only in a single species. The cloud represented by the components at 1.85 km s-1 has a Ca linear depletion δ(Ca) = 2.8 × 10-4, indicating the presence of dust. The f(H2) derived for this cloud is 0.45, and there is good velocity agreement with CO emission from MBM 151. To the best of our knowledge, this 1.85 km s-1 component toward HD 157841 is the first one found to have relative line widths that are consistent with pure thermal broadening only. We associate the 1.85 km s-1 cloud seen in our UHRF spectra with MBM 151 and conclude that HD 157841 must lie beyond ~200 pc, the estimated distance to MBM 151