bluuebunny/crossref_metadata_2025 huggingface dataset:
Fine-grained optimization method for crystal structure prediction
Authors: Terayama Kei , Yamashita Tomoki , Oguchi Tamio , Tsuda Koji
Published: July 2018

Crystal structure prediction based on first-principles calculations is often achieved by applying relaxation to randomly generated initial structures. Relaxing a structure requires multiple optimization steps. It is time consuming to fully relax all the initial structures, but it is difficult to figure out which initial structure leads to the optimal solution in advance. In this paper, we propose a optimization method for crystal structure prediction, called Look Ahead based on Quadratic Approximation, that optimally assigns optimization steps to each candidate structure. It allows us to identify the most stable structure with a minimum number of total local optimization steps. Our simulations using known systems Si, NaCl, Y2Co17, Al2O3, and GaAs showed that the computational cost can be reduced significantly compared to random search. This method can be applied for controlling all kinds of local optimizations based on first-principles calculations to obtain best results under restricted computational resources.
Rapid Screening of Ellagitannins in Natural Sources via Targeted Reporter Ion Triggered Tandem Mass Spectrometry
Authors: Bowers Jeremiah J. , Gunawardena Harsha P. , Cornu Anaëlle , Narvekar Ashwini S. , Richieu Antoine , Deffieux Denis , Quideau Stéphane , Tharayil Nishanth
Published: July 2018

Complex biomolecules present in their natural sources have been difficult to analyze using traditional analytical approaches. Ultrahigh-performance liquid chromatography (UHPLC-MS/MS) methods have the potential to enhance the discovery of a less well characterized and challenging class of biomolecules in plants, the ellagitannins. We present an approach that allows for the screening of ellagitannins by employing higher energy collision dissociation (HCD) to generate reporter ions for classification and collision-induced dissociation (CID) to generate unique fragmentation spectra for isomeric variants of previously unreported species. Ellagitannin anions efficiently form three characteristic reporter ions after HCD fragmentation that allows for the classification of unknown precursors that we call targeted reporter ion triggering (TRT). We demonstrate how a tandem HCD-CID experiment might be used to screen natural sources using UHPLC-MS/MS by application of 22 method conditions from which an optimized data-dependent acquisition (DDA) emerged. The method was verified not to yield false-positive results in complex plant matrices. We were able to identify 154 non-isomeric ellagitannins from strawberry leaves, which is 17 times higher than previously reported in the same matrix. The systematic inclusion of CID spectra for isomers of each species classified as an ellagitannin has never been possible before the development of this approach.
Bioelectric-calcineurin signaling module regulates allometric growth and size of the zebrafish fin
Authors: Daane Jacob M. , Lanni Jennifer , Rothenberg Ina , Seebohm Guiscard , Higdon Charles W. , Johnson Stephen L. , Harris Matthew P.
Published: July 2018

The establishment of relative size of organs and structures is paramount for attaining final form and function of an organism. Importantly, variation in the proportions of structures frequently underlies adaptive change in morphology in evolution and maybe a common mechanism underlying selection. However, the mechanism by which growth is integrated within tissues during development to achieve proper proportionality is poorly understood. We have shown that signaling by potassium channels mediates coordinated size regulation in zebrafish fins. Recently, calcineurin inhibitors were shown to elicit changes in zebrafish fin allometry as well. Here, we identify the potassium channelkcnk5bas a key player in integrating calcineurin’s growth effects, in part through regulation of the cytoplasmic C-terminus of the channel. We propose that the interaction between Kcnk5b and calcineurin acts as a signaling node to regulate allometric growth. Importantly, we find that this regulation is epistatic to inherent mechanisms instructing overall size as inhibition of calcineurin is able to bypass genetic instruction of size as seen insofand wild-type fins, however, it is not sufficient to re-specify positional memory of size of the fin. These findings integrate classic signaling mediators such as calcineurin with ion channel function in the regulation of size and proportion during growth.
Benzo(a)pyrene in Cigarette Smoke Enhances HIV-1 Replication through NF-κB Activation via CYP-Mediated Oxidative Stress Pathway
Authors: Ranjit Sabina , Sinha Namita , Kodidela Sunitha , Kumar Santosh
Published: July 2018

Smoking aggravates HIV-1 pathogenesis and leads to decreased responses to antiretroviral therapy. In this study, we aim to find a molecular mechanism that would explain smoking-induced HIV-1 replication. Benzo(a)pyrene (BaP), a major carcinogen in cigarette, requires metabolic activation through cytochrome P450s (CYPs) to exert its toxic effects. We hypothesized that CYP-mediated BaP metabolism generates reactive oxygen species (ROS), and the resultant oxidative stress aggravates HIV-1 replication. As expected, we observed ~3 to 4-fold increase in HIV-1 replication in U1 cells and human primary macrophages after chronic BaP exposure. We also observed ~30-fold increase in the expression of CYP1A1 at mRNA level, ~2.5-fold increase in its enzymatic activity as well as elevated ROS and cytotoxicity in U1 cells. The knock-down of the CYP1A1 gene using siRNA and treatment with selective CYP inhibitors and antioxidants significantly reduced HIV-1 replication. Further, we observed a nuclear translocation of NF-κB subunits (p50 and p65) after chronic BaP exposure, which was reduced by treatment with siRNA and antioxidants/CYP inhibitors. Suppression of NF-κB pathway using specific NF-κB inhibitors also significantly reduced HIV-1 replication. Altogether, our results suggest that BaP enhances HIV-1 replication in macrophages by a CYP-mediated oxidative stress pathway followed by the NF-κB pathway.
Interaction of LEF1 with TAZ is necessary for the osteoblastogenic activity of Wnt3a
Authors: Kida Jumpei , Hata Kenji , Nakamura Eriko , Yagi Hiroko , Takahata Yoshifumi , Murakami Tomohiko , Maeda Yoshinobu , Nishimura Riko
Published: July 2018

Canonical Wnt signalling plays an important role in osteoblast differentiation and bone formation. However, the molecular mechanisms by which canonical Wnt signalling exerts its osteoblastogenic effect remain elusive. Here, we investigated the relationship between lymphoid enhancer-binding factor 1 (LEF1) and transcriptional co-activator with PDZ-binding motif (TAZ), both of which are transcriptional regulators that mediate canonical Wnt signalling during osteoblast differentiation. Reporter assay and co-immunoprecipitation experiments revealed functional and physical interaction between LEF1 and TAZ. Overexpression of dominant-negative forms of either LEF1 or TAZ markedly inhibited Wnt3a-dependent osteoblast differentiation. Moreover, we found that LEF1 and TAZ formed a transcriptional complex with runt-related transcription factor 2 (Runx2) and that inhibition of LEF1 or TAZ by their dominant-negative forms dramatically suppressed the osteoblastogenic activity of Ruxn2. Additionally, Wnt3a enhanced osteoblast differentiation induced by bone morphogenetic protein 2 (BMP2), which stimulates osteoblast differentiation by regulating Runx2. Collectively, these findings suggest that interaction between LEF1 and TAZ is crucial for the osteoblastogenic activity of Wnt3a and that LEF1 and TAZ contribute to the cooperative effect of Wnt3a and BMP2 on osteoblast differentiation through association with Runx2.
Central insulin action induces activation of paraventricular oxytocin neurons to release oxytocin into circulation
Authors: Zhang Boyang , Nakata Masanori , Nakae Jun , Ogawa Wataru , Yada Toshihiko
Published: July 2018

Oxytocin neurons in the paraventricular nucleus (PVN) of hypothalamus regulate energy metabolism and reproduction. Plasma oxytocin concentration is reduced in obese subjects with insulin resistance. These findings prompted us to hypothesize that insulin serves to promote oxytocin release. This study examined whether insulin activates oxytocin neurons in the PVN, and explored the underlying signaling. We generated the mice deficient of 3-phosphoinositide-dependent protein kinase-1 (PDK1), a major signaling molecule particularly for insulin, specifically in oxytocin neurons (Oxy Pdk1 KO). Insulin increased cytosolic calcium concentration ([Ca2+]i) in oxytocin neurons with larger (≧25 μm) and smaller (<25 μm) diameters isolated from PVN in C57BL/6 mice. In PDK1 Oxy Pdk1 KO mice, in contrast, this effect of insulin to increase [Ca2+]i was markedly diminished in the larger-sized oxytocin neurons, while it was intact in the smaller-sized oxytocin neurons. Furthermore, intracerebroventricular insulin administration induced oxytocin release into plasma in Oxy Cre but not Oxy Pdk1 KO mice. These results demonstrate that insulin PDK1-dependently preferentially activates PVN magnocellular oxytocin neurons to release oxytocin into circulation, possibly serving as a mechanism for the interaction between metabolism and perinatal functions.
Spontaneous light-mediated magnetism in cold atoms
Authors: Krešić I. , Labeyrie G. , Robb G. R. M. , Oppo G.-L. , Gomes P. M. , Griffin P. , Kaiser R. , Ackemann T.
Published: July 2018

Cold atom setups are now commonly employed in simulations of condensed matter phenomena. We present an approach to induce strong magnetic interactions between atoms on a self-organized lattice using diffraction of light. Diffractive propagation of structured light fields leads to an exchange between phase and amplitude modulated planes which can be used to couple atomic degrees of freedom via optical pumping nonlinearities. In the experiment a cold cloud of Rb atoms placed near a retro-reflecting mirror is driven by a detuned pump laser. We demonstrate spontaneous magnetic ordering in the Zeeman sublevels of the atomic ground state: anti-ferromagnetic structures on a square lattice and ferrimagnetic structures on a hexagonal lattice in zero and a weak longitudinal magnetic field, respectively. The ordered state is destroyed by a transverse magnetic field via coherent dynamics. A connection to the transverse (quantum) Ising model is drawn.
Correction: Corrigendum: The neuroprotective action of dexmedetomidine on apoptosis, calcium entry and oxidative stress in cerebral ischemia-induced rats: Contribution of TRPM2 and TRPV1 channels
Authors: Akpınar Hatice , Nazıroğlu Mustafa , Övey Ishak Suat , Çiğ Bilal , Akpınar Orhan
Published: July 2018

Scientific Reports 6; Article number: 37196; published online: 22 November 2016; updated: 04 July 2018 In this Article, the legend of Figure 2 contains errors. The two instances of ‘TRPM2’ should read ‘TRPV1’. Figure 3 contains errors. Figure 3c was inadvertently duplicated from Figure 4c. Figure 3eis incorrect.
Catalysts for Co-processing Biomass in Oil Refining Industry
Authors: Sousa-Aguiar Eduardo Falabella , Ximenes Vitor Loureiro , Araujo Ribeiro de Almeida João Monnerat , Romano Pedro Nothaft , Carvalho Yuri
Published: July 2018

The great advantage of co-processing renewable feedstock is the reduction of the environmental footprint of refineries without major investments in new infrastructure and equipment. Nevertheless, the insertion of this feedstock is not trivial and new catalytic systems must be developed. This chapter will give to the reader a comprehensive view of the technological advances of bio-oils and vegetable oils co-processing in refineries.
Catalytic Processes and Catalyst Development in Biorefining
Authors: Taran Oxana P. , Gromov Nikolay V. , Parmon Valentin N.
Published: July 2018

The great potential of the catalytic biorefinery makes it practical for the substitution of renewable plant biomass for fossil feedstocks in new and traditional technologies. The scientific and commercial interest in the biorefinery concept has grown rapidly in the XXI century. The present Chapter is an overview of prospective catalysts and catalytic processes for valorization of plant biomass. There are three parts in the Chapter. Part 1 is a brief description of the composition and properties of the three most important components of plant biomass (cellulose, hemicelluloses and lignin). Part 2 gives insights into thermochemical and liquid-phase (more details are given in Chapter 3) processes for lignocellulose decomposition to produce bio-products (biochar, bio-oil and biogas) and platform molecules that are capable of replacing fossil raw materials (coal, oil and natural gas). Special emphasis is placed on pyrolysis, liquefaction and gasification, which transform lignocellulose into bio-oil and synthesis gas, as the methods for thermochemical depolymerization. Liquid-phase depolymerization of polysaccharides combined with dehydration, reduction, hydrogenolysis and oxidation in one-pot processes, as well as aqueous-phase reforming and biomass delignification, are discussed. Part 3 describes transformations of the main biomass-derived semi-products (syngas, bio-oil, sugars, furfurals and levulinic acid) to fuels or chemicals. Ready-to-use and promising methods for catalytic and biotechnological upgrading of bio-products to fuels and chemicals are considered.
Biohydrogen and Biomethane Production
Authors: Homs Narcis , Montané Daniel , Ramírez de la Piscina Pilar
Published: July 2018

The term biorefinery refers to any industrial installation where biomass is converted into marketable energy products, so-called biofuels, and chemical intermediates or other materials of interest to industry. Due to the diverse and heterogeneous nature of biomass, a wide array of technologies is used for its transformation into specific final products. Gaseous biofuels are one category of biorefinery products. They include methane, ideally pure enough to substitute natural gas; hydrogen; and hythane fuel: hydrogen-enriched methane with less than 10% v/v hydrogen. The different technologies used to produce gaseous biofuels depend chiefly on the type of biomass to be refined and especially its water content. This chapter reviews recent advances in the catalytic processing of biomass fractions to produce gaseous biofuels. Specifically, catalytic aqueous-phase reforming (APR), catalytic supercritical water gasification (SCWG), and the production of biosynthetic natural gas (Bio-SNG) by catalytic hydrogenation of carbon oxides (CO/CO2) from biomass streams.
Characterization of low adsorption filter membranes for electrophoresis and electrokinetic sample manipulations in microfluidic paper-based analytical devices
Authors: Casto Laura D. , Schuster Jennifer A. , Neice Claire D. , Baker Christopher A.
Published: July 2018

Low adsorption filter membrane materials facilitate effective zonal electrophoresis and electrokinetic gating in microfluidic paper-based analytical devices (μPADs).
Access to 1H-indazoles, 1H-benzoindazoles and 1H-azaindazoles from (het)aryl azides: a one-pot Staudinger-aza-Wittig reaction leading to N–N bond formation?
Authors: Alaime T. , Daniel M. , Hiebel M.-A. , Pasquinet E. , Suzenet F. , Guillaumet G.
Published: July 2018

One-pot synthesis of 1H-indazole derivatives through a proposed Staudinger-aza-Wittig tandem mechanism
Reactive two-component monolayers template bottom-up assembly of nanoparticle arrays on HOPG
Authors: Fang Chen , Zhu Hua , Chen Ou , Zimmt Matthew B.
Published: July 2018

Two triphenyleneethynylene derivatives, 1OH and 2, self-assemble a patterned monolayer (ML) at the solution–graphite (HOPG) interface. The monolayer is used to template bottom-up self-assembly of a 5 nm/19 nm double pitch pattern of gold nanoparticles on HOPG.
Recovery of xenon from air over ZIF-8 membranes
Authors: Wu Ting , Lucero Jolie , Sinnwell Michael A. , Thallapally Praveen K. , Carreon Moises A.
Published: July 2018

ZIF-8 membranes effectively separated air/Xe gas mixturesviamolecular sieving, preferential adsorption, and diffusivity differences.
Insights into the role of nanoalloy surface compositions toward catalytic acetone hydrogenation
Authors: Yang Zhao , Zhu Huaze , Zhu Huijuan , Wang Yanbing , Che Liming , Yang Zhiqing , Fang Jun , Wu Qi-Hui , Chen Bing Hui
Published: July 2018

Ultra-efficient and green catalysis for acetone hydrogenation: boosting the catalytic performance by adjusting the nanoalloy surface composition.
A new strategy for hydrophobic drug delivery using a hydrophilic polymer equipped with stacking units
Authors: Cui Peng-Fei , Zhuang Wan-Ru , Hu Xi , Xing Lei , Yu Ru-Yi , Qiao Jian-Bin , He Yu-Jing , Li Fangyuan , Ling Daishun , Jiang Hu-Lin
Published: July 2018

A highly hydrophilic polymer was used to deliver aromatic ring-containing hydrophobic agent doxorubicin (DOX)viaπ–π interaction.
Phase and morphology transformation from assembled hexagonal HTiOF3 prisms to {001} faceted TiO2 nanosheets
Authors: Zheng Yan , Hu Xun , Yang Ping
Published: July 2018

A three-stage synthesis method was developed for the preparation of TiO2 nanosheets with exposed {001} facets by a solvothermal process.
Efficient and controllable photoluminescence in novel solid solution Ca1−xSrxHf4(PO4)6:Eu2+ phosphors with high thermal stability for white light emitting diodes
Authors: Xin Shuangyu , Gao Miao , Wang Chuang , Wang Xuejiao , Zhu Ge , Zhou Faguang , Li Zhuowei , Wang Yuhua
Published: July 2018

The tunable photoluminescence properties of (Ca,Sr)Hf4(PO4)6:Eu2+ solid solution phosphors with high thermal stability and quantum efficiency were investigated.
Mixed annihilation electrogenerated chemiluminescence of iridium(iii) complexes
Authors: Soulsby Lachlan C. , Hayne David J. , Doeven Egan H. , Wilson David J. D. , Agugiaro Johnny , Connell Timothy U. , Chen Lifen , Hogan Conor F. , Kerr Emily , Adcock Jacqui L. , Donnelly Paul S. , White Jonathan M. , Francis Paul S.
Published: July 2018

The annihilation electrogenerated chemiluminescence of mixtures of Ir(iii) complexes is eliminated by manipulating reduction potentials through subtle changes in ligand structure.
Potential dependent changes in the structural and dynamical properties of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide on graphite electrodes revealed by molecular dynamics simulations
Authors: Miyamoto Hiroo , Yokota Yasuyuki , Imanishi Akihito , Inagaki Kouji , Morikawa Yoshitada , Fukui Ken-ichi
Published: July 2018

Surface distributions and the dynamic properties of an ionic liquid on charged graphite electrodes.
Chirality transfer from organic ligands to silver nanostructures via chiral polarisation of the electric field
Authors: Jakob Matthias , von Weber Alexander , Kartouzian Aras , Heiz Ulrich
Published: July 2018

Polarisation of the electric field and a chiral adsorption pattern can induce chirality into silver NPs very efficiently.
Optical properties of bimetallic compositional heterodimers
Authors: Mokkath Junais Habeeb
Published: July 2018

Many important applications of nanometer-sized metal objects arise from the light-induced interactions between their component structures.
Dynamics of N2 sticking on W(100): the decisive role of van der Waals interactions
Authors: Peña-Torres Alejandro , Busnengo H. Fabio , Juaristi J. Iñaki , Larregaray Pascal , Crespos Cédric
Published: July 2018

The reactive dynamics of N2 on W(100) has been investigated by means of quasi-classical trajectory calculations using an interpolated six-dimensional potential energy surface (PES) based on density functional theory energies obtained employing the vdW-DF2 functional.
Infrared photodissociation spectroscopy of cold cationic trimethylamine complexes
Authors: Lei Xin , Kong Xiangtao , Zhao Zhi , Zhang Bingbing , Dai Dongxu , Yang Xueming , Jiang Ling
Published: July 2018

Infrared spectroscopic studies reveal the general trends in the stepwise growth motif of trimethylamine (TMA)n+ complexes.
Defining the conditional basis of silicon phthalocyanine near-IR ligand exchange
Authors: Anderson Erin D. , Sova Stacey , Ivanic Joseph , Kelly Lisa , Schnermann Martin J.
Published: July 2018

The near-IR light induced ligand exchange of silicon phthalocyanines involves a critical radical anion intermediate and is dependent on hypoxia and a reductant.
Tetraarylpyrrolo[3,2-b]pyrroles as versatile and responsive fluorescent linkers in metal–organic frameworks
Authors: Hawes Chris S. , Ó Máille Gearóid M. , Byrne Kevin , Schmitt Wolfgang , Gunnlaugsson Thorfinnur
Published: July 2018

Pyrrolo[3,2-b]pyrrole fluorophores are incorporated into metal–organic framework linkers, giving three-dimensional materials with responsive photoluminescence behaviour.
Changing environments and biomolecule coronas: consequences and challenges for the design of environmentally acceptable engineered nanoparticles
Authors: Markiewicz Marta , Kumirska Jolanta , Lynch Iseult , Matzke Marianne , Köser Jan , Bemowsky Steve , Docter Dominic , Stauber Roland , Westmeier Dana , Stolte Stefan
Published: July 2018

Components of natural waters (salts, NOM) mitigate negative impacts of nanomaterialsviasurface passivation and stabilisation against dissolution.
Putative metal binding site in the transmembrane domain of the manganese transporter SLC30A10 is different from that of related zinc transporters
Authors: Zogzas Charles E. , Mukhopadhyay Somshuvra
Published: July 2018

Mechanism by which the cation diffusion facilitator SLC30A10 transports manganese is fundamentally different from that of previously-studied proteins in this superfamily.
NHC Hg(ii) and Pd(ii) complexes based on 1,8-dihydroxy-9,10-anthraquinone: synthesis, structure and catalysis
Authors: Zhao Zhi-Xiang , Hu Ze-Liang , Yu Shao-Cong , Liu Qing-Xiang
Published: July 2018

NHC Ag(i) and Hg(ii) complexes were prepared and characterized, and the catalytic activities of the NHC Pd(ii) complex in the Suzuki–Miyaura reaction were investigated.
Experimental and computational investigations of the photosensitive Schottky barrier diode property of an azobenzene based small organic molecule
Authors: Banerjee Saikat , Dey Arka , Ghorai Pravat , Brandão Paula , Ortega-Castro Joaquín , Frontera Antonio , Ray Partha Pratim , Saha Amrita
Published: July 2018

An azobenzene based small organic molecule has been designed to study photosensitive Schottky barrier diode property.
An effective EMI shielding material based on poly(trimethylene terephthalate) blend nanocomposites with multiwalled carbon nanotubes
Authors: A. R Ajitha , Arif P Mohammed , M. K Aswathi , Mathew Lovely P. , V. G Geethamma , Kalarikkal Nandakumar , Thomas Sabu , Volova Tatiana
Published: July 2018

The effects of blend ratio and MWCNT loading on the morphology, electrical properties and electromagnetic shielding performance of poly(trimethylene terephthalate) (PTT)/polypropylene (PP) blend nanocomposites were studied.
Engineering two-dimensional gold nanostructures using graphene oxide nanosheets as a template
Authors: Marangoni Valeria S. , Germano Lucas D. , Silva Cecilia C. C. , de Souza Eunézio A. , Maroneze Camila M.
Published: July 2018

Controlled growth of 2D gold nanostructures with tunable optical properties on the surface of graphene oxide by a surfactant-free method.
Exploiting poly(α-hydroxy acids) for the acid-mediated release of doxorubicin and reversible inside–out nanoparticle self-assembly
Authors: Khuphe Mthulisi , Ingram Nicola , Thornton Paul D.
Published: July 2018

Amphiphilic poly(hydroxyl acid) block copolymers are ideal candidates for the pH-responsive drug delivery via polymer degradation or polymer self-assembly/polymer disassembly.
Pushing the cycling stability limit of hierarchical metal oxide core/shell nanoarrays pseudocapacitor electrodes by nanoscale interface optimization
Authors: Chen Yi Min , Yu Bao Zhi , Miao Yu Qing , Gao Fei , Jing Guang Yin , Fan Hai Ming
Published: July 2018

An efficient and general strategy was developed to greatly improve the cycling stability of hierarchical oxide core/shell nanoarrays.
Strategies for the synthesis of spiropiperidines – a review of the last 10 years
Authors: Griggs Samuel D. , Tape Daniel T. , Clarke Paul A.
Published: July 2018

In this review we highlight various methods from recent literature for the synthesis of 2-, 3- and 4-spiropiperidines.
Dimethyl carbonate as a non-innocent benign solvent for the multistep continuous flow synthesis of amino alcohols
Authors: Porcar Raul , Lozano Pedro , Burguete Maria Isabel , Garcia-Verdugo Eduardo , Luis Santiago V.
Published: July 2018

An efficient methodology for the production and resolution of amino alcohols with a low environmental impact has been developed.
Automated crystal characterization with a fast neighborhood graph analysis method
Authors: Reinhart Wesley F. , Panagiotopoulos Athanassios Z.
Published: July 2018

We present a significantly improved, very fast implementation of the Neighborhood Graph Analysis technique for template-free characterization of crystal structures [W. F. Reinhart et al., Soft Matter, 2017, 13, 4733].
Insights into the passivation effect of atomic layer deposited hafnium oxide for efficiency and stability enhancement in organic solar cells
Authors: Polydorou Ermioni , Botzakaki Martha , Drivas Charalampos , Seintis Kostas , Sakellis Ilias , Soultati Anastasia , Kaltzoglou Andreas , Speliotis Thanassis , Fakis Mihalis , Palilis Leonidas C. , Kennou Stella , Fakharuddin Azhar , Schmidt-Mende Lukas , Davazoglou Dimitris , Falaras Polycarpos , Argitis Panagiotis , Krontiras Christoforos A. , Georga Stavroula N. , Vasilopoulou Maria
Published: July 2018

Atomic layer deposition of HfO2 significantly increases the efficiency and prolongs the lifetime of organic solar cells.
Temporal evolution of arch filaments as seen in He I 10 830 Å
Authors: González Manrique S. J. , Kuckein C. , Collados M. , Denker C. , Solanki S. K. , Gömöry P. , Verma M. , Balthasar H. , Lagg A. , Diercke A.
Published: July 2018

Aims. We study the evolution of an arch filament system (AFS) and of its individual arch filaments to learn about the processes occurring in them.

Methods. We observed the AFS at the GREGOR solar telescope on Tenerife at high cadence with the very fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS) in the He I 10 830 Å spectral range. The He I triplet profiles were fitted with analytic functions to infer line-of-sight (LOS) velocities to follow plasma motions within the AFS.

Results. We tracked the temporal evolution of an individual arch filament over its entire lifetime, as seen in the He I 10 830 Å triplet. The arch filament expanded in height and extended in length from 13″ to 21″. The lifetime of this arch filament is about 30 min. About 11 min after the arch filament is seen in He I, the loop top starts to rise with an average Doppler velocity of 6 km s−1. Only two minutes later, plasma drains down with supersonic velocities towards the footpoints reaching a peak velocity of up to 40 km s−1 in the chromosphere. The temporal evolution of He I 10 830 Å profiles near the leading pore showed almost ubiquitous dual red components of the He I triplet, indicating strong downflows, along with material nearly at rest within the same resolution element during the whole observing time.

Conclusions. We followed the arch filament as it carried plasma during its rise from the photosphere to the corona. The material then drained toward the photosphere, reaching supersonic velocities, along the legs of the arch filament. Our observational results support theoretical AFS models and aids in improving future models.
Upper atmospheres of terrestrial planets: Carbon dioxide cooling and the Earth’s thermospheric evolution
Authors: Johnstone C. P. , Güdel M. , Lammer H. , Kislyakova K. G.
Published: July 2018

Context.The thermal and chemical structures of the upper atmospheres of planets crucially influence losses to space and must be understood to constrain the effects of losses on atmospheric evolution.

Aims.We develop a 1D first-principles hydrodynamic atmosphere model that calculates atmospheric thermal and chemical structures for arbitrary planetary parameters, chemical compositions, and stellar inputs. We apply the model to study the reaction of the Earth’s upper atmosphere to large changes in the CO2abundance and to changes in the input solar XUV field due to the Sun’s activity evolution from 3 Gyr in the past to 2.5 Gyr in the future.

Methods.For the thermal atmosphere structure, we considered heating from the absorption of stellar X-ray, UV, and IR radiation, heating from exothermic chemical reactions, electron heating from collisions with non-thermal photoelectrons, Joule heating, cooling from IR emission by several species, thermal conduction, and energy exchanges between the neutral, ion, and electron gases. For the chemical structure, we considered ~500 chemical reactions, including 56 photoreactions, eddy and molecular diffusion, and advection. In addition, we calculated the atmospheric structure by solving the hydrodynamic equations. To solve the equations in our model, we developed the Kompot code and have provided detailed descriptions of the numerical methods used in the appendices.

Results.We verify our model by calculating the structures of the upper atmospheres of the modern Earth and Venus. By varying the CO2abundances at the lower boundary (65 km) of our Earth model, we show that the atmospheric thermal structure is significantly altered. Increasing the CO2abundances leads to massive reduction in thermospheric temperature, contraction of the atmosphere, and reductions in the ion densities indicating that CO2can significantly influence atmospheric erosion. Our models for the evolution of the Earth’s upper atmosphere indicate that the thermospheric structure has not changed significantly in the last 2 Gyr and is unlikely to change signficantly in the next few Gyr. The largest changes that we see take place between 3 and 2 Gyr ago, with even larger changes expected at even earlier times.
Spatially resolved electron density in the narrow line region of z < 0.02 radio AGNs
Authors: Kakkad D. , Groves B. , Dopita M. , Thomas A. D. , Davies R. L. , Mainieri V. , Kharb P. , Scharwächter J. , Hampton E. J. , Ho I-T.
Published: July 2018

Context. Although studying outflows in the host galaxies of active galactic nuclei (AGNs) have moved to the forefront of extragalactic astronomy in recent years, estimating the energy associated with these outflows has been a major challenge. Determining the energy associated with an outflow often involves an assumption of uniform density in the narrow line region (NLR), which spans a wide range in the literature, leading to large systematic uncertainties in energy estimation.

Aims. In this paper we present electron density maps for a sample of outflowing and non-outflowing Seyfert galaxies at z < 0.02 drawn from the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) and try to understand the origin and values of the observed density structures to reduce the systematic uncertainties in outflow energy estimation.

Methods. We use the ratio of the [S II]λ6716,6731 emission lines to derive spatially resolved electron densities (≲50–2000 cm−3). Using optical Integral Field Unit observations from the Wide Field Spectrograph (WiFeS), we are able to measure densities across the central 2–5 kpc of the selected AGN host galaxies. We compare the density maps with the positions of the H II regions derived from the narrow Hα component, ionization maps from [O III] and spatially resolved BPT diagrams to infer the origin of the observed density structures. We also use the electron density maps to construct density profiles as a function of distance from the central AGN.

Results. We find a spatial correlation between the sites of high star formation and high electron density for targets without an active ionized outflow. The non-outflowing targets also show an exponential drop in the electron density as a function of distance from the centre, with a mean exponential index of ∼0.15. The correlation between the star forming sites and electron density ceases for targets with an outflow. The density within the outflowing medium is not uniform and shows both low- and high-density sites, most likely due to the presence of shocks and highly turbulent medium. We compare these results in the context of previous results obtained from fibre and slit spectra.
The AKARI 2.5–5 micron spectra of luminous infrared galaxies in the local Universe
Authors: Inami H. , Armus L. , Matsuhara H. , Charmandaris V. , Díaz-Santos T. , Surace J. , Stierwalt S. , Ohyama Y. , Howell J. , Marshall J. , Evans A. S. , Linden S. T. , Mazzarella J.
Published: July 2018

We present AKARI 2.5–5 μm spectra of 145 local luminous infrared galaxies (LIRG; LIR ≥ 1011 L⊙) in the Great Observatories All-sky LIRG Survey (GOALS). In all of the spectra, we measure the line fluxes and equivalent widths (EQWs) of the polycyclic aromatic hydrocarbon (PAH) at 3.3 μm and the hydrogen recombination line Brα at 4.05 μm, with apertures matched to the slit sizes of the Spitzer low-resolution spectrograph and with an aperture covering ∼95% of the total flux in the AKARI two-dimensional (2D) spectra. The star formation rates (SFRs) derived from the Brα emission measured in the latter aperture agree well with SFRs estimated from LIR, when the dust extinction correction is adopted based on the 9.7 μm silicate absorption feature. Together with the Spitzer Infrared Spectrograph (IRS) 5.2–38 μm spectra, we are able to compare the emission of the PAH features detected at 3.3 μm and 6.2 μm. These are the two most commonly used near/mid-infrared indicators of starburst or active galactic nucleus (AGN) dominated galaxies. We find that the 3.3 μm and 6.2 μm PAH EQWs do not follow a linear correlation and at least a third of the galaxies classified as AGN-dominated sources using the 3.3 μm feature are classified as starbursts based on the 6.2 μm feature. These galaxies have a bluer continuum slope than galaxies that are indicated to be starburst-dominated by both PAH features. The bluer continuum emission suggests that their continuum is dominated by stellar emission rather than hot dust. We also find that the median Spitzer/IRS spectra of these sources are remarkably similar to the pure starburst-dominated sources indicated by high PAH EQWs in both 3.3 μm and 6.2 μm. Based on these results, we propose a revised starburst/AGN diagnostic diagram using 2–5 μm data: the 3.3 μm PAH EQW and the continuum color, Fν(4.3 μm)/Fν(2.8 μm). We use the AKARI and Spitzer spectra to examine the performance of our new starburst/AGN diagnostics and to estimate 3.3 μm PAH fluxes using the James Webb Space Telescope (JWST) photometric bands in the redshift range 0 < z < 5. Of the known PAH features and mid-infrared high ionization emission lines used as starburst/AGN indicators, only the 3.3 μm PAH feature is observable with JWST at z > 3.5, because the rest of the features at longer wavelengths fall outside the JWST wavelength coverage.
Searching for g modes
Authors: Appourchaux T. , Boumier P. , Leibacher J. W. , Corbard T.
Published: July 2018

Context. The recent claims of g-mode detection have restarted the search for these potentially extremely important modes. These claims can be reassessed in view of the different data sets available from the SoHO instruments and ground-based instruments.

Aims. We produce a new calibration of the GOLF data with a more consistent p-mode amplitude and a more consistent time shift correction compared to the time series used in the past.

Methods. The calibration of 22 yr of GOLF data is done with a simpler approach that uses only the predictive radial velocity of the SoHO spacecraft as a reference. Using p modes, we measure and correct the time shift between ground- and space-based instruments and the GOLF instrument.

Results. The p-mode velocity calibration is now consistent to within a few percent with other instruments. The remaining time shifts are within ±5 s for 99.8% of the time series.
Size effect in the electronic transport of thin films of Bi2Se3
Authors: Marchenkov V.V. , Chistyakov V.V. , Huang J.C.A. , Perevozchikova Y.A. , Domozhirova A.N. , Eisterer M.
Published: July 2018

Thin films of a topological insulator (TI) Bi2Se3 of various thicknesses from 20 nm to 75 nm were obtained. The resistivity measurements were carried out according to the conventional 4-contact DC technique. This allows to “separate” the bulk and surface conductivities at different temperatures and magnetic fields. It was suggested that similar effects should be observed in other TIs and systems with inhomogeneous distribution of dc-current on sample cross section.
Image reconstruction algorithms for the microwave holographic vision system with reliable gap detection at theoretical limits
Authors: Leshchiner Dmitry , Zvezdin Konstantin , Popkov Anatoly , Chepkov Grigory , Perlo Pietro
Published: July 2018

We present a reliable image reconstruction algorithm suitable for a microwave holographic vision system with several sensors coupled to the spin-diode based microwave detector and a single emission source. An objective is, by reconstructing the spatial microwave scattering density on the scene, to detect the presence and the nature of road obstacles impeding driving in the near vehicle zone. The idea of holographic visualization is to reconstruct the spatial microwave scattering density of an object by detecting an amplitude and phase of a reflected signal by lattice of sensors. We discuss versions of an algorithm, determine and analyse its resolution limits for various distances with different number of sensors for a one-dimensional test problem of detecting two walls (or posts) separated by a gap at a fixed distance. The maximal interval between sensors needed for a reliable reconstruction equals approximately Fresnel zone width. We show that maximal resolution achieved by our algorithm with an appropriate number of sensors was about 40% of Fresnel zone width for wall detection and about 30% of zone width for gap detection.
Inverse spin Hall effect in heterostructures “nanostructured ferromagnet/topological insulator”
Authors: Petrov P.N. , Davydova M.D. , Skirdkov P.N. , Zvezdin K.A. , Lin J.G. , Huang J.C.A.
Published: July 2018

Interaction between magnetization dynamics and spin polarized electronic transport has been studied for ferromagnet nanodisk situated upon a 3D topological insulator (TI) film. Resonant magnetization dynamics leads to generation of spin current, which flows into the topological insulator, where spin to charge conversion occurs. Using micromagnetic simulations for magnetization dynamics we estimate the dc voltage, which is created due to this process in topological insulator. Contribution from different modes, which are characteristic for nanodisks, to the voltage was calculated.
Magnetic interaction at the interface of epitaxial manganite film and (TbCo2/FeCo)n superlattice
Authors: Grishin Alexander S. , Ovsyannikov Gennady A. , Klimov Alexey A. , Demidov Viktor V. , Constantinian Karen Y. , Borisenko Igor V. , Preobrazhensky Vladimir L. , Tiercelin Nicolas , Pernod Phillipe
Published: July 2018

Hybrid magnetic heterostructures made of epitaxial manganite La0.7Sr0.3MnO3 thin film and intermetallic superlattice (TeCo2/FeCo)n were prepared on orthorhombic NdGaO3 substrates and characterized by means of magneto-optical Kerr effect and magnetoresistance. Experimental data show that magnetic interaction between La0.7Sr0.3MnO3 and (TeCo2 /FeCo)n is of the antiferromagnetic type. The features observed in magnetotransport characteristics are caused by the magnetization reversal at the interface between manganite thin film and intermetallic superlattice.
Calculation of CPP-and CIP-magnitoresistance in multilayer magnetic structures
Authors: Romanovskii Dmitry E. , Prudnikov Vladimir V. , Prudnikov Pavel V. , Mamonova Marina V.
Published: July 2018

A Monte Carlo simulation of magnetic properties for structures Fe/Cr/Fe and Co/Cu/Co, constructed from two ferromagnetic films divided by nonmagnetic film are carried out. The calculation of the magnetoresistance is carried out in case of CPP and CIP geometry for different thicknesses of the ferromagnetic films with the use of the anisotropic Heisenberg model for determination of magnetic properties. It was shown, that the obtained temperature dependence for the magnetoresistance agrees very well with experimental results.
Magnetically intercalated multilayer silicene
Authors: Tokmachev Andrey M. , Averyanov Dmitry V. , Karateev Igor A. , Parfenov Oleg E. , Kondratev Oleg A. , Taldenkov Alexander N. , Storchak Vyacheslav G.
Published: July 2018

Silicene, a Si-based analogue of graphene, is predicted to exhibit topological electronic phases with exotic properties capable to revolutionize electronics. In particular, the silicene structure is highly advantageous for spintronics. However, lack of synthetic routes to free-standing and magnetically functionalized silicene compounds prevents experimental corroboration of the predictions. Here we synthesize EuSi2, multilayer silicene intercalated with inherently magnetic Eu atoms, on SrSi2/Si(001) templates. The resulting films are formed by crystallites of two mutually orthogonal orientations. The structure is firmly established with electron diffraction, X-ray diffraction and electron microscopy. The compound EuSi2 exhibits non-trivial magnetic and transport properties. The data are compared with those for EuSi2 films grown on SrSi2/Si(111) templates.
Spin-filter state of Au-Co nanowires
Authors: Smelova Ekaterina , Tsysar Kseniya , Saletsky Alexander
Published: July 2018

Our theoretical study reveals the dependence of quantum conductance of Au-Co nanowires on their atomic structure. The results show the emergence of spin-filter state in one-dimensional Au-Co bimetallic nanowires. We found the existence of two transmission regime in Au-Co nanowires with low and high conductivity 1G0 and 2G0 for “zig-zag” and linear nanowire correspondingly. The study of transmission spectra of Au-Co nanowires reveals the control capability of spin transport regime by changing of bias voltage between bulk electrodes.
Determination of magnetoelastic oscillations in ferrite plate with different values of anisotropy constant
Authors: Kotov Leonid , Severin Pavel , Vlasov Vladimir , Beznosikov Dmitry
Published: July 2018

The maximum amplitudes of magnetic and elastic oscillations are calculated at various material parameters and parameters of external fields. Normally and tangentially magnetized anisotropic magnetic plates were considered. To obtain the maximum amplitudes with additional constraints, the simulated annealing method was used. The behaviour of the magnetic and elastic components of the oscillations was considered. The changes in the position of the magnetization vector and the equilibrium displacements as a function of the first anisotropy constant were revealed.
Temperature dependence of Gilbert damping in manganite/normal metal heterostructure
Authors: Shcaihulov Timur A. , Demidov Victor V. , Borisenko Igor V. , Ovsyannikov Gennady A.
Published: July 2018

The temperature dependence of the spin-pumping effect on the Gilbert damping in a bilayer based on epitaxial manganite film grown on neodymium galate substrate was investigated by measuring of the linewidth of the ferromagnetic resonance spectrum (FMR). Ferromagnetic resonance in thin ferromagnetic manganite La0.7Sr0.3MnO3 (LSMO) films is used to produce a spin current at the interface between a metallic and a ferromagnetic layer. Pt/LSMO/NGO, Au/LSMO/NGO and LSMO/NGO heterostrucutres were measured. An increase of the linewidth in FMR spectrum at the temperature lower liquid nitrogen temperature (77K) is observed .
Magnetostatic waves in a medium with damping
Authors: Makarov Pavel , Maltceva Lidiya , Kotov Leonid , Shcheglov Vladimir
Published: July 2018

By means of consistent solution of the motion equation for magnetization the consideration of energy dissipation for magnetostatic surface waves propagating on in-plane magnetized ferrite plate is regarded. The complex character of the wave number caused by the dissipation is revealed. In this case the dispersion relations for the real and imaginary parts of the wave number are obtained. It is shown that dispersion curves are limited both by the wave number and frequency, and these restrictions tighten with an increase in the damping parameter. Also, it is predicted that there is a new set of branches of the backward dissipative waves. Both for forward and backward waves there is a critical value of the damping parameter and propagation angle, beyond which it does not exist.
Tamm plasmon-polaritons structures with Bi-substituted garnet layers
Authors: Mikhailova Tatyana , Shaposhnikov Alexander , Prokopov Anatoly , Karavainikov Andrey , Tomilin Sergey , Lyashko Sergey , Berzhansky Vladimir
Published: July 2018

New original Tamm plasmon-polaritons (TPP) structures with Bi-substituted iron garnet and Au plasmonic layers were proposed, synthesized and investigated. The structures with single and double garnet layers were modelled to form a TPP mode at the center of photonic band gab. The top Au layer has the gradient thickness varied in the range from 0 to 65.2 nm. It was found the features of TPP resonances as a function of the thickness of metal coating. The resonances on TPP have the maximum optical quality factor and transmission at the vicinity of Au thickness of 30 nm. These configurations are optimum to form the highest intensity of electric field of light wave in the area of the magnetic layers. It was found the spectral blue and red shifts of TPP mode with increasing of Au thickness. The blue and red shifts can be explained respectively by structural and thickness changes of Au coating. The maximum resonant values of Faraday rotation were –2.1° at 664 nm and –12.3° at 645 nm for structures with single and double garnet layers, respectively, and thickness of Au coating of 65.2 nm.
Electrical properties of ferromagnetic-insulator nanocomposites
Authors: Kalinin Yu.E. , Makagonov V.A. , Sitnikov A.V. , Granovsky A.B.
Published: July 2018

Analysis of experimental studying of electrical properties of ferromagnetic-insulator nanocomposites is presented in the paper.
The origin of fine structure in magnetization curve of αCoV2O6
Authors: Kudasov Yuri , Kozabaranov Roman
Published: July 2018

Multiple field-induced plateaus in αCoV2O6 at low temperatures were revealed earlier by M. Lenertz et al. [J. Phys. Chem. C 115, 17190 (2011)] and carefully investigated recently by M. Nandi and P. Mandal [J. Appl. Phys. 119, 133904 (2016)]. Four equidistant steps were observed in the magnetization curve. We present a model to describe this phenomenon. A magnetic structure of this substance is formed by highly anisotropic triangular lattice of Ising chains running along the b axis. Due to a three-fold degeneracy of three-sublattice magnetic ordering, domain boundaries appear. Their transformation under magnetic field variation leads to two additional steps in the 1/3 magnetization plateau and gives rise to complex magnetic behavior observed experimentally. The domain structure in αCoV2O6 occurs to be strongly anisotropic because a lifetime of the metastable states depends greatly on the configuration orientation. A strong dependence of the magnetization curve on magnetic field sweep time is predicted.
Coexistence of the magnetically ordered and Haldane states in (Y1-xNdx)2BaNiO5
Authors: Popova Elena , Klimin Sergei , Popova Marina , Klingeler RÜdiger , BÜchner Bernd , Vasiliev Alexander
Published: July 2018

The magnetic properties of (Y1-xNdx)2BaNiO5 with x = 0.01, 0.02, 0.03, 0.04, and 0.05 are investigated by means of specific heat, magnetic susceptibility, and spectroscopic measurements. We estimate a magnetic contribution of the neodymium subsystem into the magnetic susceptibility and specific heat using temperature dependencies of the splitting of the ground Kramers doublet of the Nd3+ ion obtained from spectroscopic experiments. We estimate also the contribution caused by nickel chain breaks and by ferrons. Different scenarios of low-temperature magnetic behavior are discussed.