bluuebunny/crossref_metadata_2025 huggingface dataset:
A theoretical investigation on the atmospheric degradation of the radical: reactions with NO, NO2, and NO3
Authors: Feng Bo , Sun Cuihong , Zhao Weiwei , Zhang Shaowen
Published: May 2020

The mechanisms of with NO, NO2, and NO3 were studied to reveal the atmospheric fate of , comprehensively.
Hit-to-lead optimization of novel benzimidazole phenylacetamides as broad spectrum trypanosomacides
Authors: McNamara Nicole , Rahmani Raphael , Sykes Melissa L. , Avery Vicky M. , Baell Jonathan
Published: May 2020

A series of benzimidazole phenylacetamides were developed from a phenotypic hit as novel trypanosomacides for Chagas disease and human African trypanosomiasis.
Improved electrochemical properties and kinetics of an LiMn2O4-based cathode co-modifiedviaCu doping with truncated octahedron morphology
Authors: Wang Shimin , Liu Honglei , Xiang Mingwu , Guo Junming , Bai Wei , Bai Hongli , Liu Xiaofang , Su Changwei
Published: May 2020

Spinel LiMn2O4has been widely investigated as a cathode material for lithium-ion batteries, but it suffers from a limited cycle life due to the dissolution of Mn and structural distortion.
Fabrication and evaluation of bioinspired pDA@TiO2-based ibuprofen-imprinted nanocomposite membranes for highly selective adsorption and separation applications
Authors: Yan Ming , Wu Yilin
Published: May 2020

Highly selective and constitutionally stable TiO2/pDA-based nanocomposite-imprinted membranes for selective separation of ibuprofen molecules.
A fluorescent sensor based on oyster mushroom-carbon dots for sensing nitroarenes in aqueous solutions
Authors: Zulfajri Muhammad , Rasool Akhtar , Huang Genin Gary
Published: May 2020

The synthesis of OM-CDs and their sensing application for NAs.
A carbon-based memristor design for associative learning activities and neuromorphic computing
Authors: Pei Yifei , Zhou Zhenyu , Chen Andy Paul , Chen Jingsheng , Yan Xiaobing
Published: May 2020

A model based on carbon conductive filaments (CFs) for a memristor based on carbon quantum dots (QDs) is proposed for the first time.
Coordination tailoring of water-labile 3D MOFs to fabricate ultrathin 2D MOF nanosheets
Authors: Wen Yuehong , Liu Qiang , Su Shaodong , Yang Yuying , Li Xiaofang , Zhu Qi-Long , Wu Xintao
Published: May 2020

A coordination tailoring top-down delamination strategy involving the controllable partial disassembly of a water-labile 3D MOF has been explored to fabricate ultrathin 2D MOF nanosheets.
Correction: Development of polycationic micelles as an efficient delivery system of antibiotics for overcoming the biological barriers to reverse multidrug resistance in Escherichia coli
Authors: Guo Rong , Li Keke , Qin Jing , Niu Shengli , Hong Wei
Published: May 2020

Correction for ‘Development of polycationic micelles as an efficient delivery system of antibiotics for overcoming the biological barriers to reverse multidrug resistance in Escherichia coli’ by Rong Guo et al., Nanoscale, 2020, DOI: 10.1039/d0nr01366h.
Divergent synthesis of oxindole derivatives via controllable reactions of isatin-derived para-quinone methides with sulfur ylides
Authors: You Yong , Quan Bao-Xue , Wang Zhen-Hua , Zhao Jian-Qiang , Yuan Wei-Cheng
Published: May 2020

A catalyst-free and controllable reaction of isatin-derived para-quinone methides with sulfur ylides was developed, and it enables the divergent synthesis of two valuable oxindoles.
Light interactions with supracrystals either deposited on a substrate or dispersed in water
Authors: Pileni Marie Paule
Published: May 2020

Nanocrystals with low size distribution are able to self-assemble into a 3D crystalline structure called colloidal crystals or super/supracrystals.
Promising performance of chemically exfoliated Zr-doped MoS2 nanosheets for catalytic and antibacterial applications
Authors: Ikram M. , Tabassum R. , Qumar U. , Ali S. , Ul-Hamid A. , Haider A. , Raza A. , Imran M. , Ali S.
Published: May 2020

Nanostructured materials incorporated with biological reducing agents have shown significant potential for use in bactericidal applications.
Switchable adhesion of soft composites induced by a magnetic field
Authors: Testa Paolo , Chappuis Benoît , Kistler Sabrina , Style Robert W. , Heyderman Laura J. , Dufresne Eric R.
Published: May 2020

Magnetically-switchable adhesion of a two-phase composite to non-magnetic objects is achieved by magnetically addressing the material dissipative properties.
Carbon black-supported FM–N–C (FM = Fe, Co, and Ni) single-atom catalysts synthesized by the self-catalysis of oxygen-coordinated ferrous metal atoms
Authors: Wang Lina , Zhang Junwei , Zheng Lirong , Yang Jiarui , Li Yongcheng , Wan Xin , Liu Xiaofang , Zhang Xixiang , Yu Ronghai , Shui Jianglan
Published: May 2020

Carbon nanomaterials have abundant sources but are difficult to use directly as a support for single atom catalysts (SACs) due to the lack of strong anchoring forces to restrict the aggregation of metal atoms during the high-temperature treatment.
Efficient hydroxylation of benzene to phenol by H2O2 using Ni-doped CuWO4 on carbon nitride as a catalyst under solar irradiation and its structure–activity correlation
Authors: Basyach Purashri , Guha Ankur Kanti , Borthakur Sukanya , Kalita Lisamoni , Chetia Pubali , Sonowal Karanika , Saikia Lakshi
Published: May 2020

A series of environmentally benign and highly efficient Z-scheme Ni-doped CuWO4 nanoparticles on graphitic carbon nitride (g-C3N4) were synthesized.
The thick waxy coat of mycobacteria, a protective layer against antibiotics and the host's immune system
Authors: Batt Sarah M. , Minnikin David E. , Besra Gurdyal S.
Published: May 2020

Tuberculosis, caused by the pathogenic bacterium Mycobacterium tuberculosis (Mtb), is the leading cause of death from an infectious disease, with a mortality rate of over a million people per year. This pathogen's remarkable resilience and infectivity is largely due to its unique waxy cell envelope, 40% of which comprises complex lipids. Therefore, an understanding of the structure and function of the cell wall lipids is of huge indirect clinical significance. This review provides a synopsis of the cell envelope and the major lipids contained within, including structure, biosynthesis and roles in pathogenesis.
Potential antiviral agents of Rosmarinus officinalis extract against herpes viruses 1 and 2
Authors: AL-Megrin Wafa A. , AlSadhan Norah A. , Metwally Dina M. , Al-Talhi Razan A. , El-Khadragy Manal F. , Abdel-Hafez Lina J. M.
Published: May 2020

Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) belong to the herpesviridae family and cause neurological disorders by infecting the nervous system. The present study aimed to investigate the effects of Rosmarinus officinalis L. (rosemary) extract against HSV-1 and HSV-2 in vitro. The antioxidant activity of this extract was investigated by superoxide anion and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical assays. Rosemary extract was evaluated by an HSV-1 antiviral assay, in which viral replication in Vero cells was determined and quantified using a cytopathic effect assay. The present study showed that rosemary extract at 30 µg/ml caused 55% inhibition of HSV-1 plaques, whereas 40 µg/ml rosemary extract caused 65% inhibition of HSV-2 plaques. The extracts completely inhibited HSV-1 and HSV-2 plaque formation at 50 µg/ml. Scavenging activity of the superoxide anion radical was observed at 65.74 mg/ml, whereas 50% scavenging activity of the DPPH radical was observed at 67.34 mg/ml. These data suggest that rosemary extract may be suitable as a topical prophylactic or therapeutic agent for herpes viral infections. However, further research is required to elucidate the plant’s active constituents, which may be useful in drug development.
Mutations in genes encoding regulators of mRNA decapping and translation initiation: links to intellectual disability
Authors: Weil Dominique , Piton Amélie , Lessel Davor , Standart Nancy
Published: May 2020

Intellectual disability (ID) affects at least 1% of the population, and typically presents in the first few years of life. ID is characterized by impairments in cognition and adaptive behavior and is often accompanied by further delays in language and motor skills, as seen in many neurodevelopmental disorders (NDD). Recent widespread high-throughput approaches that utilize whole-exome sequencing or whole-genome sequencing have allowed for a considerable increase in the identification of these pathogenic variants in monogenic forms of ID. Notwithstanding this progress, the molecular and cellular consequences of the identified mutations remain mostly unknown. This is particularly important as the associated protein dysfunctions are the prerequisite to the identification of targets for novel drugs of these rare disorders. Recent Next-Generation sequencing-based studies have further established that mutations in genes encoding proteins involved in RNA metabolism are a major cause of NDD. Here, we review recent studies linking germline mutations in genes encoding factors mediating mRNA decay and regulators of translation, namely DCPS, EDC3, DDX6 helicase and ID. These RNA-binding proteins have well-established roles in mRNA decapping and/or translational repression, and the mutations abrogate their ability to remove 5′ caps from mRNA, diminish their interactions with cofactors and stabilize sub-sets of transcripts. Additional genes encoding RNA helicases with roles in translation including DDX3X and DHX30 have also been linked to NDD. Given the speed in the acquisition, analysis and sharing of sequencing data, and the importance of post-transcriptional regulation for brain development, we anticipate mutations in more such factors being identified and functionally characterized.
Electroabsorption‐modulated laser as optical transmitter and receiver: status and opportunities
Authors: Schrenk Bernhard
Published: May 2020

The rapid growth of digital services has led to a widespread deployment of opto‐electronics that furnish the Internet as an efficient communication backbone. The electroabsorption‐modulated laser (EML) is a representative example of a monolithic integrated electro‐optic converter that has early become a commodity: it has been widely adopted in telecommunication networks in virtue of its cost‐ and energy‐efficient light generation and modulation. This study reviews the state‐of‐the‐art of EML applications. Despite its simplicity, the EML addresses numerous use cases that require either the transmission or the reception of optical signals, such as equaliser‐free high‐bandwidth intensity modulation/direct‐detection links at low signal drive, analogue signal transmission with high signal integrity, spectral sculpting for dispersion‐tolerant transmission and vector modulation. Full‐duplex transceiver functionality in lieu of a pair of dedicated half‐duplex sub‐systems is eventually attained by combining transmission and reception. This strategy of significantly reducing the cost for a bidirectional communication engine will be discussed for coherent digital data and analogue radio‐over‐fibre transmission and optical ranging. The maturity of EMLs as coherent transceivers will be evidenced by a small penalty for realising full‐duplex transmission and the accomplishment of homodyne detection, which obviates digital signal processing for the purpose of signal recovery.
Constraining the abundance of dark matter in the central region of the galaxy cluster MACS J1206.2−0847 with a free-form strong lensing analysis
Authors: Manjón-García Alberto , Diego Jose M. , Herranz Diego , Lam Daniel
Published: May 2020

We performed a free-form strong lensing analysis of the galaxy cluster MACS J1206.2−0847 in order to estimate and constrain its inner dark matter distribution. The free-form method estimates the cluster total mass distribution without using any prior information about the underlying mass. We used 97 multiple lensed images belonging to 27 background sources and derived several models, which are consistent with the data. Among these models, we focus on those that better reproduce the radial images that are closest to the centre of the cluster. These radial images are the best probes of the dark matter distribution in the central region and constrain the mass distribution down to distances ∼7 kpc from the centre. We find that the morphology of the innermost radial arcs is due to the elongated morphology of the dark matter halo. We estimate the stellar mass contribution of the brightest cluster galaxy and subtracted it from the total mass in order to quantify the amount of dark matter in the central region. We fitted the derived dark matter density profile with a gNFW, which is characterised byrs= 167 kpc,ρs= 6.7 × 106 M⊙kpc−3, andγgNFW= 0.70. These results are consistent with a dynamically relaxed cluster. This inner slope is smaller than the cannonicalγ = 1 predicted by standard CDM models. This slope does not favour self-interacting models for which a shallower slope would be expected.
Average motion of emerging solar active region polarities
Authors: Schunker H. , Baumgartner C. , Birch A. C. , Cameron R. H. , Braun D. C. , Gizon L.
Published: May 2020

Context.The tilt of solar active regions described by Joy’s law is essential for converting a toroidal field to a poloidal field in Babcock-Leighton dynamo models. In thin flux tube models the Coriolis force causes what we observe as Joy’s law, acting on east-west flows as they rise towards the surface.

Aims.Our goal is to measure the evolution of the average tilt angle of hundreds of active regions as they emerge, so that we can constrain the origins of Joy’s law.

Methods.We measured the tilt angle of the primary bipoles in 153 emerging active regions (EARs) in the Solar Dynamics Observatory Helioseismic Emerging Active Region survey. We used line-of-sight magnetic field measurements averaged over 6 h to define the polarities and measure the tilt angle up to four days after emergence.

Results.We find that at the time of emergence the polarities are on average aligned east-west, and that neither the separation nor the tilt depends on latitude. We do find, however, that EARs at higher latitudes have a faster north-south separation speed than those closer to the equator at the emergence time. After emergence, the tilt angle increases and Joy’s law is evident about two days later. The scatter in the tilt angle is independent of flux until about one day after emergence, when we find that higher-flux regions have a smaller scatter in tilt angle than lower-flux regions.

Conclusions.Our finding that active regions emerge with an east-west alignment is consistent with earlier observations, but is still surprising since thin flux tube models predict that tilt angles of rising flux tubes are generated below the surface. Previously reported tilt angle relaxation of deeply anchored flux tubes can be largely explained by the change in east-west separation. We conclude that Joy’s law is caused by an inherent north-south separation speed present when the flux first reaches the surface, and that the scatter in the tilt angle is consistent with buffeting of the polarities by supergranulation.
Distinguishing between flaring and nonflaring active regions
Authors: Hazra Soumitra , Sardar Gopal , Chowdhury Partha
Published: May 2020

Context.Large-scale solar eruptions significantly affect space weather and damage space-based human infrastructures. It is necessary to predict large-scale solar eruptions; it will enable us to protect the vulnerable infrastructures of our modern society.

Aims.We investigate the difference between flaring and nonflaring active regions. We also investigate whether it is possible to forecast a solar flare.

Methods.We used photospheric vector magnetogram data from the Solar Dynamic Observatory’s Helioseismic Magnetic Imager to study the time evolution of photospheric magnetic parameters on the solar surface. We built a database of flaring and nonflaring active regions observed on the solar surface from 2010 to 2017. We trained a machine-learning algorithm with the time evolution of these active region parameters. Finally, we estimated the performance obtained from the machine-learning algorithm.

Results.The strength of some magnetic parameters such as the total unsigned magnetic flux, the total unsigned magnetic helicity, the total unsigned vertical current, and the total photospheric magnetic energy density in flaring active regions are much higher than those of the non-flaring regions. These magnetic parameters in a flaring active region evolve fast and are complex. We are able to obtain a good forecasting capability with a relatively high value of true skill statistic. We also find that time evolution of the total unsigned magnetic helicity and the total unsigned magnetic flux provides a very high ability of distinguishing flaring and nonflaring active regions.

Conclusions.We can distinguish a flaring active region from a nonflaring region with good accuracy. We confirm that there is no single common parameter that can distinguish all flaring active regions from the nonflaring regions. However, the time evolution of the top two magnetic parameters, the total unsigned magnetic flux and the total unsigned magnetic helicity, have a very high distinguishing capability.
Following the TraCS of exoplanets with Pan-Planets: Wendelstein-1b and Wendelstein-2b
Authors: Obermeier C. , Steuer J. , Kellermann H. , Saglia R. P. , Henning Th. , Riffeser A. , Hopp U. , Stefansson G. , Cañas C. , Ninan J. , Mahadevan S. , Isaacson H. , Howard A. W. , Livingston J. , Koppenhoefer J. , Bender R.
Published: May 2020

Hot Jupiters seem to get rarer with decreasing stellar mass. The goal of the Pan-Planets transit survey was the detection of such planets and a statistical characterization of their frequency. Here, we announce the discovery and validation of two planets found in that survey, Wendelstein-1b and Wendelstein-2b, which are two short-period hot Jupiters that orbit late K host stars. We validated them both by the traditional method of radial velocity measurements with the HIgh Resolution Echelle Spectrometer and the Habitable-zone Planet Finder instruments and then by their Transit Color Signature (TraCS). We observed the targets in the wavelength range of 4000−24 000 Å and performed a simultaneous multiband transit fit and additionally determined their thermal emission via secondary eclipse observations. Wendelstein-1b is a hot Jupiter with a radius of 1.0314−0.0061+0.0061 RJ and mass of 0.592−0.129+0.0165 MJ, orbiting a K7V dwarf star at a period of 2.66 d, and has an estimated surface temperature of about 1727−90+78 K. Wendelstein-2b is a hot Jupiter with a radius of 1.1592−0.0210+0.0204 RJ and a mass of 0.731−0.311+0.0541 MJ, orbiting a K6V dwarf star at a period of 1.75 d, and has an estimated surface temperature of about 1852−140+120 K. With this, we demonstrate that multiband photometry is an effective way of validating transiting exoplanets, in particular for fainter targets since radial velocity follow-up becomes more and more costly for those targets.
Circumnuclear regions of different BPT types in star-forming MaNGA galaxies: AGN detectability
Authors: Pilyugin L. S. , Grebel E. K. , Zinchenko I. A. , Lara-López M. A. , Nefedyev Y. A. , Shulga V. M.
Published: May 2020

We consider the circumnuclear regions of star-forming MaNGA galaxies. The spaxels spectra are classified as active-galactic-nucleus-like (AGN-like), H II-region-like (or SF-like), and intermediate (INT) spectra according to their positions on the Baldwin-Phillips-Terlevich (BPT) diagram. There are the following four configurations of the radiation distributions in the circumnuclear regions in (massive) galaxies: (1) AGN+INT, the innermost region of the AGN-like radiation is surrounded by a ring of radiation of the intermediate type; (2) INT, the central area of radiation of the intermediate type; (3) SF+INT, the inner region of the H II-region-like radiation is surrounded by a ring of radiation of the intermediate type; and (4) SF, the central area of the H II-region-like radiation only. The low ionization nuclear emission line regions (LINERs) of configurations 1 and 2 are examined. The spaxel spectra of the LINERs form a sequences on the BPT diagram, that is, they lie along the known AGN-SF mixing line trajectories. The diagnostic line ratios of the spaxels spectra change smoothly with radius, from AGN-like (or INT) line ratios at the galactic center to H II-region-like at larger galactocentric distances. This is in agreement with the paradigm that the LINERs are excited by AGN activity. We found that the AGN and INT radiation in the circumnuclear region is accompanied by an enhanced gas velocity dispersionσgas. The radius of the area of the AGN and INT radiation is similar to the radius of the area with enhancedσgas, and the centralσgas, ccorrelates with the luminosity of the AGN+INT area. We assume that the gas velocity dispersion can serve as an indicator of the AGN activity. An appreciable enhancement ofσgas, cwas also measured in the SF-type centers of massive galaxies. The values ofσgas, cfor the SF-type centers partly overlap with those of the AGN-type centers. This suggests that the manifestation of the circumnuclear region as AGN or as SF on the BPT diagram depends not only on the value ofσgas, c(the level of the AGN activity) but it is also governed by an additional parameter(s). We find that there is a demarcation line between the positions of the AGN-type and SF-type objects on the central gas velocity dispersion – central Hαsurface brightness diagram, in the sense that an object with a given value ofσgas, cis an AGN-type only if the central Hαsurface brightness is lower than some value.
Understanding Saturn’s interior from theCassiniGrand Finale gravity measurements
Authors: Ni Dongdong
Published: May 2020

Context.Measurements of Saturn’s gravity field byCassiniGrand Finale have been acquired with high precision. It has been demonstrated that the even gravitational harmonicsJ6–J10have larger absolute values than the predictions by typical rigid-body interior models. A four-layer structure model, proposed to interpret Juno’s gravity measurements for Jupiter, has been applied to Saturn, but great attention was paid to the depth of zonal flows in order to interpret the large absolute values ofJ6–J10.

Aims.We aim to understand the internal structure and interior composition of Saturn with a similar model for Jupiter. The additional uncertainties in Saturn’s structure and composition are investigated in detail, such as rotation periods, atmospheric helium mass fractions, and flow-induced gravity corrections. Also, we investigate the effect of equations of state for hydrogen and helium on the predictions of the core mass and heavy element abundance.

Methods.In the four-layer structure model, we adjusted the heavy element abundances in the outer two envelopes and the mass of the compact core in order to reproduce Saturn’s equatorial radius as well as theCassiniGrand Finale gravity measurements corrected by the flow-induced gravity signals. Different four-layer interior models are specified in terms of the rotation period, the atmospheric helium mass fraction, and the flow-induced gravity corrections. Two different ab initio equations of state for hydrogen and helium were used in interior structure calculations. Optimized calculations were then performed to explore Saturn’s internal structure and composition.

Results.It is found that the absolute values ofJ6–J10tend to increase with increasing deep rotation rate and depend on the equations of state adopted in interior calculations. Saturn’s deep rotation rate and atmospheric helium mass fraction are important to determine the distribution of helium and heavy elements in the outer envelopes. We also show that the core mass and heavy element abundance in Saturn are dependent upon the deep rotation rate, the atmospheric helium mass fraction, the flow-induced gravity corrections, and the equations of state for hydrogen and helium.
Relationship between air traffic demand, safety and complexity in high density airspace in Europe
Authors: Pejovic Tamara , Natjasov Fedja , Crnogorac Dusan
Published: May 2020

Air traffic performance of the European air traffic system depends not only on traffic demand but also on airspace structure and its traffic distribution. These structural (airspace structure) and flow characteristics (factors such as traffic volume, climbing/descending traffic, mix of aircraft type, military area activity) influence airspace complexity, which can affect controller workload and influence the probability of safety occurrence. In other words, all these dynamic and static complexity components can potentially have an impact upon the safety of the air traffic management (ATM) system. Having in mind fluctuation in traffic on daily, seasonal or annual level in certain airspace, a few questions arise: How changes in traffic demand influence complexity and conflict risk? Is there any correlation between traffic demand, conflict risk and complexity? Are there any differences between seasons? For that purpose, an investigation is performed on FAB Europe Central (FABEC) airspace, based on two weeks of operated traffic during the summer and winter of 2017. Air traffic complexity is estimated using the EUROCONTROL complexity metrics, while conflict risk is assessed using the conflict risk assessment simulation tool. Results show that certain positive relationship exists between traffic demand, conflict risk and complexity.
Composite risk index: the new Safety Performance Indicator of risk exposure
Authors: Pejovic Tamara
Published: May 2020

Conceptually, all safety programmes desire accurate safety risk quantification in order to provide a meaningful expression of risk. As there are typically, multiple safety risks associated with a system or event, the quantification of total safety risk is a major challenge. One possible way to define and accept the total safety risk of any system is using the concept of a composite risk estimate. This paper represents development of the new safety performance indicator and overall methodology that could be used to measure the performance of European ATM systems as a whole and its individual entities. It describes the computation of the Composite Risk Index (CRI), logic behind it, its use (on the example EUROCONTROL Member States) and limitations and areas of potential improvement. CRI represents a cumulative risk value calculated aggregating all reported, assessed and severity classified key safety-related incidents to form an index. This measure of risk exposure is based on probability and severity that considers the human perception of equivalent risk. Overall idea behind CRI is that the performance of safety system can be analysed within three important broad categories: the quality of reporting system with reporting entity, measured risks within the system, and human perception of risk.
Das Druckschmerz-Manual
Authors: Corts Magga
Published: May 2020

Druckschmerzen können sowohl durch mechanischen Druck ausgelöst werden als auch von innen durch überschwelliges Gewebe entstehen, welches benachbartes Gewebe komprimiert. Je nach Pathologie lassen sich verschiedene Bereiche des Körpers manuell auf Druckdolenzen, also mechanisch ausgelöste Druckschmerzen, hin untersuchen. Druckschmerzen sind als Hinweiszeichen zu verstehen; entsprechende Verdachtsdiagnosen müssen mit weiteren diagnostischen Mitteln gesichert werden.
Willkommener Eindringling
Authors: Kuhn Alexandra
Published: May 2020

Das Indische Springkraut (Impatiens glandulifera) ist eine vor allem in der Bachblütentherapie, nordindischen Volksheilkunde und Kulinarik verwendete Pflanze.
Catalytic pyrolysis of biodiesel surrogate over HZSM-5 zeolite catalyst
Authors: Qian Si-yu , Feng Bei-bei , Zhai Yi-tong , Zhao Wei , Wang Lei , Ao Cheng-cheng , Liu Yi , Liu Jing , Zhang Li-dong
Published: May 2020

To obtain insight into the catalytic reaction mechanism of biodiesels over ZSM-5 zeolites, the pyrolysis and catalytic pyrolysis of methyl butanoate, a biodiesel surrogate, with H-type ZSM-5 (HZSM-5) were performed in a flow re-actor under atmospheric pressure. The pyrolysis products were identified and quantified using gas chromatography-mass spectrometry (GC-MS). Kinetic modelling and experimental results revealed that H-atom abstraction in the gas phase was the primary pathway for methyl butanoate decomposition during pyrolysis, but dissociating to ketene and methanol over HZSM-5 was the primary pathway for methyl butanoate consumption during catalytic pyrolysis. The initial decomposition temperature of methyl butanoate was reduced by approximately 300 K over HZSM-5 compared to that for the uncatalyzed reaction. In addition, the apparent activation energies of methyl butanoate under catalytic pyrolysis and homogeneous pyrolysis conditions were obtained using the Arrhenius equation. The significantly reduced apparent activation energy confirmed the catalytic performance of HZSM-5 for methyl butanoate pyrolysis. The activation temperature may also affect some catalytic properties of HZSM-5. Overall, this study can be used to guide subsequent catalytic combustion for practical biodiesel fuels.
Charge-state independent anomalous transport for a wide range of different impurity species observed at Wendelstein 7-X
Authors: Langenberg A. , Wegner Th. , Pablant N. A. , Marchuk O. , Geiger B. , Tamura N. , Bussiahn R. , Kubkowska M. , Mollén A. , Traverso P. , Smith H. M. , Fuchert G. , Bozhenkov S. , Damm H. , Pasch E. , Brunner K.-J. , Knauer J. , Beurskens M. , Burhenn R. , Wolf R. C. ,   W7-X Team
Published: May 2020

In this paper, the plasma volume averaged impurity confinement of selected charge states and impurity species has been characterized for the Stellarator Wendelstein 7-X (W7-X), covering a wide range of atomic charges (Z = 12–44) and atomic masses (M = 28–184). A comparison of the experimental findings to theoretical neoclassical and turbulent transport expectations suggests, aside from/in addition to the neoclassical transport, an additional significant anomalous transport mechanism, which is not inconsistent with the predictions of a turbulence dominated impurity transport and is in agreement with the experimental results from recent transport studies based on the direct measurements of impurity diffusion profiles, performed at W7-X.
First-principles description of intra-chain exciton migration in an oligo(para-phenylene vinylene) chain. I. Generalized Frenkel–Holstein Hamiltonian
Authors: Binder Robert , Bonfanti Matteo , Lauvergnat David , Burghardt Irene
Published: May 2020

A generalized Frenkel–Holstein Hamiltonian is constructed to describe exciton migration in oligo(para-phenylene vinylene) chains, based on excited state electronic structure data for an oligomer comprising 20 monomer units (OPV-20). Time-dependent density functional theory calculations using the ωB97XD hybrid functional are employed in conjunction with a transition density analysis to study the low-lying singlet excitations and demonstrate that these can be characterized to a good approximation as a Frenkel exciton manifold. Based on these findings, we employ the analytic mapping procedure of Binder et al. [J. Chem. Phys. 141, 014101 (2014)] to translate one-dimensional (1D) and two-dimensional (2D) potential energy surface (PES) scans to a fully anharmonic, generalized Frenkel–Holstein (FH) Hamiltonian. A 1D PES scan is carried out for intra-ring quinoid distortion modes, while 2D PES scans are performed for the anharmonically coupled inter-monomer torsional and vinylene bridge bond length alternation modes. The kinetic energy is constructed in curvilinear coordinates by an exact numerical procedure, using the TNUM Fortran code. As a result, a fully molecular-based, generalized FH Hamiltonian is obtained, which is subsequently employed for quantum exciton dynamics simulations, as shown in Paper II [R. Binder and I. Burghardt, J. Chem. Phys. 152, 204120 (2020)].
Shock compression of molybdenum single crystals to 110 GPa: Elastic–plastic deformation and crystal anisotropy
Authors: Oniyama Tomoyuki , Gupta Yogendra M. , Ravichandran Guruswami
Published: May 2020

To investigate the role of crystal anisotropy on the elastic–plastic deformation of BCC single crystals at high shock stresses, molybdenum (Mo) single crystals were shock compressed along the [100], [111], and [110] orientations at elastic impact stresses between 20 and 110 GPa. Laser interferometry was used to measure shock wave velocities and particle velocity histories. Along the [100] and [111] orientations, elastic–plastic waves (two wave structure) were observed up to 110 GPa. Along the [110] orientation, the two wave structure was observed only up to 90 GPa. The measured elastic wave amplitudes were analyzed to determine crystal anisotropy effects, impact stress dependence, and the activated slip systems on the Hugoniot elastic limit. The findings from our work have provided insight into the role of crystal anisotropy on the elastic–plastic deformation under shock compression at high stresses.
Monolayer 2D quantum materials subjected to gamma irradiation in high-vacuum for nuclear and space applications
Authors: Elafandi Salah , Christiansen Robert , Azam Nurul , Cichon Max , Park Minseo , Hamilton Michael C. , Mahjouri-Samani Masoud
Published: May 2020

The stability and reliability of emerging two-dimensional (2D) quantum materials subjected to harsh environments, such as high-energy radiation, are of high importance, particularly in the fields of space, defense, and energy applications. In this work, we explored the effects of gamma radiation on the structural and optical properties of monolayer WSe2 and WS2 crystals. Raman and photoluminescence spectroscopies were employed to study and probe radiation-induced changes to the samples after exposure to intense gamma radiation (from a 60Co source) in a high-vacuum environment (∼1 × 10−6 Torr) and with various exposure times to vary the total accumulated dosage (up to ∼56 Mrad). In general, very small changes in optical or vibrational properties were observed compared to pristine samples, suggesting noteworthy stability even for high dosages of gamma radiation. Moreover, we found that WSe2 monolayer samples exhibited higher tolerance to gamma radiation compared to WS2 samples. These findings highlight the inherent stability of these 2D quantum materials in harsh radioactive environments, which motivates further investigation of their optical, electrical, and structural properties and exploration for use in future space, energy, and defense applications.
Wake topology and dynamics over a slender body at a high incidence and their relation to structural loading
Authors: Yuan Qihang , Yarusevych Serhiy
Published: May 2020

The flow over a slender cylindrical body with a hemisphere end was studied experimentally using a combination of force balance and time-resolved particle image velocity measurements. The investigation was performed at a subcritical Reynolds number (Re = 11 000) over a range of high incidence angles from 30° to 90°. The results show that significant cross-flow loading occurs for a range of incidence angles from 50° to 70°, with maximum mean and fluctuating loads taking place at 60°. Within this range of incidence angles, the loading has a bimodal nature, with intermittent switching between two states associated with the positive and negative cross-flow loading direction. The analysis of simultaneous force and wake measurements reveals that the two loading regimes are produced by two distinct wake topologies defined by strongly asymmetric vortex dynamics near the tip of the model. The results provide insight into salient features of the wake development and vortex dynamics and show that transient changes in the cross-flow force direction progress through a consistent change in the wake structure between two bounding quasi-steady states.
Temperature dependent inverse spin Hall effect in Co/Pt spintronic emitters
Authors: Matthiesen M. , Afanasiev D. , Hortensius J. R. , van Thiel T. C. , Medapalli R. , Fullerton E. E. , Caviglia A. D.
Published: May 2020

In bilayers of ferromagnets and heavy metals, which form the so-called spintronic emitters, the phenomena of ultrafast demagnetization and the inverse spin Hall effect (ISHE) conspire to yield remarkably efficient emission of electric pulses in the THz band. Light-induced demagnetization of the ferromagnet launches a pulse of spin current into the heavy metal, wherein it bifurcates into a radiative charge transient due to the ISHE. The influence of temperature on this combined effect should depend on both the magnetic phase diagram and the microscopic origin of spin Hall conductivity, but its exact dependence remains to be clarified. Here, we experimentally study the temperature dependence of an archetypal spintronic emitter, the Co/Pt bilayer, using electro-optic sampling of the emitted THz pulses in the time domain. The emission amplitude is attenuated with decreasing temperature, consistent with an inverse spin Hall effect in platinum of predominantly intrinsic origin.
Manipulation of Gilbert damping in ultrathin half-metallic Co2FeAl1+x by composition-deficiency-compensation
Authors: Gao Qinwu , Lu Xianyang , Chen Zhendong , Sun Yizhe , Zhang Kunpeng , Zhao Yafei , Ning Jiai , Wang Ruifeng , Zhang Junran , Nie Yuefeng , Ruan Xuezhong , Wu Jing , He Liang , Zhang Rong , Liu Bo , Meng Hao , Xu Yongbing
Published: May 2020

Gilbert damping is of crucial importance for spintronic devices due to its practical effect on the response time and energy consumption. Lower damping would enable more energy-efficient excitations and, thus, less current is needed. The Gilbert damping constant of the Co2FeAl film, a half-metal material important for spintronics with its 100% spin polarization at the Fermi level, has shown an abnormal increase at the thin film limit due to the inter-diffusion of Al atoms. Here, we report that the Gilbert damping of ultra-thin Co2FeAl1+x films of nanometer thicknesses can be effectively tuned by delicately controlling the stoichiometric ratio during the growth. Gilbert damping has been found to be the lowest of 0.065 in Co2FeAl1+0.1, which is deduced by ∼50% compared to that in Co2FeAl. We have further found that the damping constant of the ultra-thin Co2FeAl1+0.1 film is restored to the value of 0.062 of the nominal stoichiometric Co2FeAl by compensating the Al composition deficiency, as supported by 10.37% of composition change from scanning transmission electron microscopy with energy-dispersive-spectroscopy. This work offers a unique path to manipulate the Gilbert damping constant in ultra-thin Co2FeAl films by Al concentration control.
Effects of different attractants and human scent on mesocarnivore detection at camera traps
Authors: Heinlein Bracy W. , Urbanek Rachael E. , Olfenbuttel Colleen , Dukes Casey G.
Published: May 2020

Abstract
ContextCamera traps paired with baits and scented lures can be used to monitor mesocarnivore populations, but not all attractants are equally effective. Several studies have investigated the efficacy of different attractants on the success of luring mesocarnivores to camera traps; fewer studies have examined the effect of human scent at camera traps.
AimsWe sought to determine the effects of human scent, four attractants and the interaction between attractants and human scent in luring mesocarnivores to camera traps.
Methods We compared the success of synthetic fermented egg (SFE), fatty acid scent (FAS) tablets, castor oil, and sardines against a control of no attractant in luring mesocarnivores to camera traps. We deployed each attractant and the control with either no regard to masking human scent or attempting to restrict human scent for a total of 10 treatments, and replicated treatments eight to nine times in two different phases. We investigated whether: (1) any attractants increased the probability of capturing a mesocarnivore at a camera trap; (2) not masking human scent affected the probability of capturing a mesocarnivore at a camera trap; and (3) any attractants increased the probability of repeat detections at a given camera trap. We also analysed the behaviour (i.e. speed and distance to attractant) of each mesocarnivore in relation to the attractants.
Key resultsSardines improved capture success compared with the control treatments, whereas SFE, castor oil, and FAS tablets had no effect when all mesocarnivores were included in the analyses. Masking human scent did not affect detection rates in the multispecies analyses. Individually, the detection of some species depended on the interactions between masking (or not masking) human scent and some attractants.
ConclusionsSardines were the most effective as a broad-based attractant for mesocarnivores. Mesocarnivores approached traps baited with sardines at slower rates, which allows for a higher success of capturing an image of the animal.
ImplicationsHuman scent may not need to be masked when deploying camera traps for multispecies mesocarnivore studies, but researchers should be aware that individual species respond differently to attractants and may have higher capture success with species-specific attractants.
Anisotropy links cell shapes to tissue flow during convergent extension
Authors: Wang Xun , Merkel Matthias , Sutter Leo B. , Erdemci-Tandogan Gonca , Manning M. Lisa , Kasza Karen E.
Published: May 2020

Within developing embryos, tissues flow and reorganize dramatically on timescales as short as minutes. This includes epithelial tissues, which often narrow and elongate in convergent extension movements due to anisotropies in external forces or in internal cell-generated forces. However, the mechanisms that allow or prevent tissue reorganization, especially in the presence of strongly anisotropic forces, remain unclear. We study this question in the converging and extending
Drosophila
germband epithelium, which displays planar-polarized myosin II and experiences anisotropic forces from neighboring tissues. We show that, in contrast to isotropic tissues, cell shape alone is not sufficient to predict the onset of rapid cell rearrangement. From theoretical considerations and vertex model simulations, we predict that in anisotropic tissues, two experimentally accessible metrics of cell patterns—the cell shape index and a cell alignment index—are required to determine whether an anisotropic tissue is in a solid-like or fluid-like state. We show that changes in cell shape and alignment over time in the
Drosophila
germband predict the onset of rapid cell rearrangement in both wild-type and
snail twist
mutant embryos, where our theoretical prediction is further improved when we also account for cell packing disorder. These findings suggest that convergent extension is associated with a transition to more fluid-like tissue behavior, which may help accommodate tissue-shape changes during rapid developmental events.
Dynamical processes of interstitial diffusion in a two-dimensional colloidal crystal
Authors: Kim Sung-Cheol , Yu Lichao , Pertsinidis Alexandros , Ling Xinsheng Sean
Published: May 2020

Significance

Defects in crystalline materials are of broad and fundamental interest. In condensed-matter physics, defect dynamics contain essential information about the microscopic processes of crystal formation and melting. Two-dimensional melting (2D) is widely accepted to be mediated by the proliferation of edge dislocations. In 2D crystals, vacancies and interstitials are, in fact, bound pairs of edge dislocations and disclinations. They are expected to play critical roles in 2D melting. We demonstrated significant progress in quantifying the dynamical processes of interstitials. We also propose a simple yet powerful method in visualizing the time-averaged configurations of the defects, providing a direct tool to assess whether the detailed balance is obeyed or violated in the fluctuating processes in a lattice.
Inhibitory antibodies identify unique sites of therapeutic vulnerability in rhinovirus and other enteroviruses
Authors: Meng Bing , Lan Keke , Xie Jia , Lerner Richard A. , Wilson Ian A. , Yang Bei
Published: May 2020

The existence of multiple serotypes renders vaccine development challenging for most viruses in the
Enterovirus
genus. An alternative and potentially more viable strategy for control of these viruses is to develop broad-spectrum antivirals by targeting highly conserved proteins that are indispensable for the virus life cycle, such as the 3C protease. Previously, two single-chain antibody fragments, YDF and GGVV, were reported to effectively inhibit human rhinovirus 14 proliferation. Here, we found that both single-chain antibody fragments target sites on the 3C protease that are distinct from its known drug site (peptidase active site) and possess different mechanisms of inhibition. YDF does not block the active site but instead noncompetitively inhibits 3C peptidase activity through an allosteric effect that is rarely seen for antibody protease inhibitors. Meanwhile, GGVV antagonizes the less-explored regulatory function of 3C in genome replication. The interaction between 3C and the viral genome 5′ noncoding region has been reported to be important for enterovirus genome replication. Here, the interface between human rhinovirus 14 3C and its 5′ noncoding region was probed by hydrogen–deuterium exchange coupled mass spectrometry and found to partially overlap with the interface between GGVV and 3C. Consistently, prebinding of GGVV completely abolishes interaction between human rhinovirus 14 3C and its 5′ noncoding region. The epitopes of YDF and GGVV, therefore, represent two additional sites of therapeutic vulnerability in rhinovirus. Importantly, the GGVV epitope appears to be conserved across many enteroviruses, suggesting that it is a promising target for pan-enterovirus inhibitor screening and design.
Metal-induced sensor mobilization turns on affinity to activate regulator for metal detoxification in live bacteria
Authors: Fu Bing , Sengupta Kushal , Genova Lauren A. , Santiago Ace George , Jung Won , Krzemiński Łukasz , Chakraborty Udit Kumar , Zhang Wenyao , Chen Peng
Published: May 2020

Metal detoxification is essential for bacteria’s survival in adverse environments and their pathogenesis in hosts. Understanding the underlying mechanisms is crucial for devising antibacterial treatments. In the Gram-negative bacterium
Escherichia coli
, membrane-bound sensor CusS and its response regulator CusR together regulate the transcription of the
cus
operon that plays important roles in cells’ resistance to copper/silver, and they belong to the two-component systems (TCSs) that are ubiquitous across various organisms and regulate diverse cellular functions. In vitro protein reconstitution and associated biochemical/physical studies have provided significant insights into the functions and mechanisms of CusS–CusR and related TCSs. Such studies are challenging regarding multidomain membrane proteins like CusS and also lack the physiological environment, particularly the native spatial context of proteins inside a cell. Here, we use stroboscopic single-molecule imaging and tracking to probe the dynamic behaviors of both CusS and CusR in live cells, in combination with protein- or residue-specific genetic manipulations. We find that copper stress leads to a cellular protein concentration increase and a concurrent mobilization of CusS out of clustered states in the membrane. We show that the mobilized CusS has significant interactions with CusR for signal transduction and that CusS’s affinity toward CusR switches on upon sensing copper at the interfacial metal-binding sites in CusS’s periplasmic sensor domains, prior to ATP binding and autophosphorylation at CusS’s cytoplasmic kinase domain(s). The observed CusS mobilization upon stimulation and its surprisingly early interaction with CusR likely ensure an efficient signal transduction by providing proper conformation and avoiding futile cross talks.