bluuebunny/crossref_metadata_2025 huggingface dataset:
Large structural heterogeneity in submicrometer BaTiO3 revealed via Eu+3 photoluminescence study
Authors: De Arnab , Ranjan Rajeev
Published: September 2020

Apart from being a model ferroelectric, BaTiO3 and its derivatives are materials of considerable technological importance in the capacitor industry and as a potential Pb-free piezoelectric. Here, we have examined BaTiO3 for its propensity to stabilize local low symmetry distortions and induce structural heterogeneity for two different situations, namely, (1) by introducing inhomogeneous lattice strain and (2) by restricting the average grain size to the submicrometer regime. We have introduced Eu+3 ions in BaTiO3 in a very dilute concentration to act as local probes. Our strategy relies on exploiting the great sensitivity of the 5D0 → 7F2 transition of Eu+3 with regard to the variation in the asymmetric distribution of the ligand field around itself to probe the structural heterogeneity developed in BaTiO3. The Eu+3 photoluminescence signal revealed a remarkable increase in the local structural heterogeneity in submicrometer (∼0.4 μm) sized BaTiO3. This manifests as an ∼170% increase in the intensity of the 7F2 band with respect to the structure insensitive 7F1 band. Although to a lesser extent, a similar scenario was observed when the large grain BaTiO3 develops residual strain. The structural insights presented here can be helpful in explaining the properties of BaTiO3-based multilayered ceramics wherein the two conditions of submicrometer size and residual strain is a common occurrence.
Diffusion in bulk metallic glasses
Authors: Syutkin V. M. , Grebenkin S.
Published: September 2020

Due to the simple structure, bulk metallic glasses are very convenient model systems for studying the mechanism of atom diffusion in disordered media. In this paper, we analyze literature data on diffusion for a set of atoms in the metallic alloy Zr46.75Ti8.25Cu7.5Ni10Be27.5 (Vitreloy 4) above and below the glass transition temperature. We show that the activation energy of diffusion, E, is controlled by the high-frequency shear modulus, G∞, and can be presented in the form E=const×G∞ in the whole temperature range studied. We conclude that the displacements of a group of atoms in metallic alloys occur during the elastic shear deformation of their surroundings. The diffusion mechanism is the same both in the glassy state and in the supercooled melt.
Feedthrough parasitic nonlinear resonance in micromechanical oscillators
Authors: Chen Dongyang , Zhang Hemin , Sun Jiangkun , Pandit Milind , Sobreviela Guillermo , Wang Yong , Seshia Ashwin , Xie Jin
Published: September 2020

Mechanical oscillators incorporating miniaturized structures to transduce mesoscopic motion as readable electrical signals are often limited by the feedthrough effect (FE) because oscillation features are corrupted. The knowledge of FE parasitic resonance hitherto is only demonstrated in the linear regime. Herein, we reveal the nature of phenomenological FE parasitic nonlinear resonance. An inverse distortion in the spectra resulting from the superposition of Duffing nonlinearity and the FE is observed and modeled with physical insight into the governing parameters. We find that the manipulation of electromechanical coupling of the oscillator can fully de-embed the FE, while the device oscillates at the nonlinear bifurcation point under phase control. The generic nature of our model indicates that similar dynamic behaviors will occur for the nonlinear resonant systems containing the FE, regardless of transducing techniques. The strategy of on-chip FE control in our capacitive platform is scalable and can be suitably transformed for application in oscillators employing alternative transducers.
High frequency lithium niobate film-thickness-mode optomechanical resonator
Authors: Shen Mohan , Xie Jiacheng , Zou Chang-Ling , Xu Yuntao , Fu Wei , Tang Hong X.
Published: September 2020

High-frequency optomechanical resonators are in demand as transduction devices to bridge microwave and optical fields. Thin-film lithium niobate is a promising platform for implementing high-frequency optomechanics for its low optical loss and strong piezoelectric coefficients. However, its strong piezoelectricity is also known to introduce excess phonon loss. Here, we present lithium niobate optomechanical resonators with film-thickness-mode mechanical resonances up to 5.2 GHz, reaching the operating frequency regime of superconducting qubits. By engineering the mechanical anchor to minimize the phonon loss, we achieve a high quality factor up to 12 500 at cryogenic temperatures and, hence, a frequency-quality factor product of 6.6 × 1013. Our system also features interference between piezo-optomechanical and electro-optic modulation. A theoretical model is derived to analyze these two effects and their interference.
A half-metallic ferrimagnet of CeCu3Cr4O12 with 4f itinerant electron
Authors: Li Hongping , Ge Zhizhong , Sun An , Zhu Zhipeng , Tian Yi , Song Weiyu
Published: September 2020

Half-metals have drawn extensive interest due to their unique electronic structure and wide application in spintronics. We report an A-site-ordered quadruple perovskite CeCu3Cr4O12 with half-metallic behaviors using first-principles calculations. Our calculations demonstrate that CeCu3Cr4O12 is a ferrimagnet with a saturated magnetic moment of 7.00 μB f.u.–1. Effective ferrimagnetic interactions are generated from the antiparallel spin arrangement between the A′-site Cu and B-site Cr. The electronic structure analyses reveal that CeCu3Cr4O12 exhibits half-metal performance, which can be attributed to the mixed-valence of B-site Cr. More importantly, a small amount of 4f itinerant electrons are located on the A-site Ce, i.e., both itinerant electron magnetism and localized magnetic moments are observed in the theoretical calculations. The charge distribution in this system is confirmed to be Ce(4−δ)+Cu2+3Cr(3.5+δ)+4O2−12. The physical properties of the AA′3B4O12-type perovskite CeCu3Cr4O12 revealed in this study show that this class of materials shows promise in applications of half-metals.
Mean-field kinetic theory approach to Langmuir evaporation of polyatomic liquids
Authors: Busuioc Sergiu , Gibelli Livio
Published: September 2020

The evaporation of polyatomic liquids into near-vacuum conditions is investigated by using the Enskog–Vlasov model. Molecules are approximated as classical rigid rotators, and the collisional energy exchanges between the translational and rotational degrees of freedom are dealt with by the Borgnakke–Larsen method. The distribution function of evaporated molecules and the evaporation coefficient are evaluated in a wide range of liquid bulk temperatures and inelastic collision fractions. It is found that the translational velocity distribution function is well approximated by a drifted bi-Maxwellian, while the rotational energy follows the Boltzmann distribution at a temperature that varies between the separation and the parallel temperatures as the inelastic collision fraction increases. The evaporation coefficient based on the separation temperature turns out to be independent of the inelastic collision fraction and only mildly dependent on the liquid bulk temperature.
Tracking ferroelectric domain formation during epitaxial growth of PbTiO3 films
Authors: Sarott Martin F. , Fiebig Manfred , Trassin Morgan
Published: September 2020

The arrangement of domains and domain walls is a crucial factor in determining the functional properties of ferroelectric materials. Here, we track the ferroelectric domain formation mechanism in ultrathin PbTiO3 films in real time during epitaxial growth using in situ optical second harmonic generation. In combination with complementary ex situ piezoresponse force microscopy and second harmonic generation imaging, we unambiguously identify the tensile-epitaxial-strain-induced partial conversion of out-of-plane-polarized c-domains into in-plane-polarized a-domains. We further show that, in the strongly compressive epitaxial regime, the c-to-a conversion can be shifted to the early stage of the growth to favor a remarkable randomization in the distribution of a- and c-domains. This unprecedented access to the domain-formation dynamics constitutes an important step toward deterministic domain architectures in technologically relevant ultrathin ferroelectrics which, in turn, is valuable for the development of functional ferroelectric and piezoelectric structures.
The effect of inner-sphere reorganization on charge separated state lifetimes at sensitized TiO2 interfaces
Authors: Kessinger M. C. , Brillhart C. , Vaissier Welborn V. , Morris A. J.
Published: September 2020

Improving the efficiency of photo-electrocatalytic cells depends on controlling the rates of interfacial electron transfer to promote the formation of long-lived charge separated states. Ultimately, for efficient catalytic assemblies to see widespread implementation, repeated electron transfer in the absence of charge recombination needs to be realized. In this study, a series of manganese-based transition metal complexes known to undergo charge transfer-induced spin crossover are employed to study how significant increases in inner-sphere reorganization energy affect the rates of interfacial electron transfer. Each complex is characterized by transient spectroscopic and electrochemical methods to calculate the rate of electron transfer to a model chromophore anchored to the surface of a TiO2 film. Likewise, open-circuit voltage decay measurements were used to determine the voltage-dependent lifetime of injected electrons in TiO2 in the presence of each complex. To further characterize the rates of electronic recombination, density functional theory was used to calculate the inner-sphere and outer-sphere reorganization energy for each complex. These calculations were then combined with classical Marcus theory to determine the theoretical rate of back-electron transfer from the TiO2 conduction band. These results show that, in model complexes, a significant reduction in the recombination rate constant is achieved for complexes possessing a significant inner-sphere reorganization energy.
Effects of forced frequency oscillations and unsteady wakes on the separation-induced transition in pressure gradient dominated flows
Authors: Sengupta Aditi , Tucker Paul
Published: September 2020

The individual and cumulative effects of forced frequency oscillations and unsteady wakes, on the separation-induced transition caused by an adverse pressure gradient on a flat plate geometry, are investigated. The flat plate is subjected to a streamwise pressure gradient via an inviscid contour wall, which is representative of the pressure gradient on the suction surface of a low pressure turbine. Periodic Gaussian wakes are imposed at the inflow to mimic the effect of upstream stator wakes. The transitional and turbulent regimes of the flow are investigated using instantaneous and time-averaged flow fields, turbulent kinetic energy (TKE) budgets and a disturbance enstrophy-based nonlinear receptivity analysis based on direct numerical simulations. The impression of the wake in the boundary layer convects 50%–70% slower than the wake. The case with oscillations and wakes is most effective in triggering early transition and reducing the region of separation, specifically the secondary separation bubble is completely suppressed. Enhanced near-wall mixing is observed with a shift in the inflection point of the velocity profile toward the wall. The budget of the TKE shows the dominance of the production term for all cases considered. The disturbance enstrophy transport equation shows the role of the vortex stretching, enstrophy diffusion and dissipation for flows with wakes. Finally, a linear spatio-temporal receptivity analysis is performed for velocity profiles in the attached and separated boundary layer. This provides a description of the effects of pressure gradient and unsteady wakes in the transition to turbulence.
Silver gull harassment of humpback whales in Exmouth Gulf, Western Australia
Authors: Harkness Philippa , Sprogis Kate R.
Published: September 2020

We share observations of silver gulls (Chroicocephalus novaehollandiae) harassing humpback whales (Megaptera novaeangliae) in Exmouth Gulf, Western Australia, between August and October in 2018 and 2019. Sixteen events were recorded of gulls pecking at the skin of 16 mothers and 2 calves resting on the surface. Data were collected opportunistically from a research vessel covering 5474.2km (565h). Events were documented through photographs and unmanned aerial vehicle video recordings and persisted for an average minimum time of 20.73min (range 2.50–46.85min). At least one event of a gull consistently gouging in a pre-existing lesion was recorded on a mother. Changes in behavioural activity from the whales, which varied from slipping under the surface to travelling and performing instantaneous behavioural events, were observed in 94% (15/16) of events. These are the first known records of birds attacking humpback whales. The results are comparable to early events of kelp gull (Larus dominicanus) harassment of southern right whales (Eubalaena australis) off Península Valdés, Argentina, where events have escalated over the past 50 years to consistent attacks on the whales’ skin and blubber. Future research is required to monitor the trajectory of these interactions to inform management.
National Cervical Screening Program renewal in Australia: survey of clinician views and attitudes
Authors: Sweeney Sally , Cheng Yan , Botfield Jessica R. , Bateson Deborah
Published: September 2020

From 1 December 2017, the National Cervical Screening Program was renewed in Australia, with updated national cervical screening guidelines released. This study was performed to determine clinicians’ familiarity with the updated guidelines and explore their views and attitudes towards the renewed program. Clinicians providing cervical screening in New South Wales, Australia, were invited to complete an online survey in 2018. Of the 241 clinicians who responded, 91.5% supported the change to 5-yearly human papillomavirus screening from the age of 25 years. However, nearly 13% indicated they did not know where to access the renewed guidelines and 37% had never or rarely accessed them. Open-ended responses highlighted clinicians’ concerns about missed cancers and missed opportunities for health checks. Those raising these concerns accessed the guidelines less frequently. The findings highlight important areas for additional education and support for clinicians in translating guidelines into practice to ensure successful delivery of the renewed program.
Placing language in an integrated understanding system: Next steps toward human-level performance in neural language models
Authors: McClelland James L. , Hill Felix , Rudolph Maja , Baldridge Jason , Schütze Hinrich
Published: September 2020

Language is crucial for human intelligence, but what exactly is its role? We take language to be a part of a system for understanding and communicating about situations. In humans, these abilities emerge gradually from experience and depend on domain-general principles of biological neural networks: connection-based learning, distributed representation, and context-sensitive, mutual constraint satisfaction-based processing. Current artificial language processing systems rely on the same domain general principles, embodied in artificial neural networks. Indeed, recent progress in this field depends on query-based attention, which extends the ability of these systems to exploit context and has contributed to remarkable breakthroughs. Nevertheless, most current models focus exclusively on language-internal tasks, limiting their ability to perform tasks that depend on understanding situations. These systems also lack memory for the contents of prior situations outside of a fixed contextual span. We describe the organization of the brain’s distributed understanding system, which includes a fast learning system that addresses the memory problem. We sketch a framework for future models of understanding drawing equally on cognitive neuroscience and artificial intelligence and exploiting query-based attention. We highlight relevant current directions and consider further developments needed to fully capture human-level language understanding in a computational system.
Characterization of alkylguaiacol-degrading cytochromes P450 for the biocatalytic valorization of lignin
Authors: Fetherolf Morgan M. , Levy-Booth David J. , Navas Laura E. , Liu Jie , Grigg Jason C. , Wilson Andrew , Katahira Rui , Beckham Gregg T. , Mohn William W. , Eltis Lindsay D.
Published: September 2020

Significance

Upgrading lignin, an underutilized component of biomass, is essential for the sustainability of biorefineries. Biocatalysis has considerable potential for upgrading lignin, but our lack of knowledge of relevant enzymes and pathways has limited its application. Herein, we describe a microbial pathway responsible for catabolizing alkylguaiacols, a major component of several industrial lignin streams. Catabolism is initiated by a cytochrome P450, with related P450s catalyzing the
O
-demethylation of different lignin-derived guaiacols and subsequent catabolism depending on the substitution pattern of the guaiacol. Importantly, the alkylguaiacol catabolic pathway enables bacterial growth on corn stover lignin produced by reductive catalytic fractionation. Overall, these insights greatly facilitate the engineering of P450s and bacteria to biocatalytically upgrade lignin.
Different mechanisms underlie implicit visual statistical learning in honey bees and humans
Authors: Avarguès-Weber Aurore , Finke Valerie , Nagy Márton , Szabó Tūnde , d’Amaro Daniele , Dyer Adrian G. , Fiser József
Published: September 2020

Significance

Do animals encode statistical information about visual patterns the same way as humans do? If so, humans’ superior visual cognitive skills must depend on some other factors; if not, the nature of the differences can provide hints about what makes human learning so versatile. We provide a systematic comparison of automatic visual learning in humans and honey bees, showing that while bees do extract statistical information about co-occurrence contingencies of visual scenes, in contrast to humans, they do not automatically encode conditional information. Thus, acquiring implicit knowledge about the statistical properties of the visual environment may be a general mechanism in animals, but the richer representation developed automatically by humans might require specific probabilistic computational faculties.
A connectivity portfolio effect stabilizes marine reserve performance
Authors: Harrison Hugo B. , Bode Michael , Williamson David H. , Berumen Michael L. , Jones Geoffrey P.
Published: September 2020

Significance

Networks of no-take marine reserves support local fisheries by ensuring a consistent supply of juvenile fish. We measured larval dispersal patterns for a highly exploited coral grouper and quantified temporal fluctuations in the recruitment contribution from a network of no-take marine reserves on the Great Barrier Reef. Although recruitment contributions from individual reserves are extremely variable, the reserve network generates a connectivity portfolio effect that successfully dampens the volatility of larval supply to nearby coral reefs. Our findings demonstrate that effective reserve networks can yield previously unrecognized stabilizing benefits that ensure a consistent replenishment of exploited fish stocks.
Particle motion on burned and vegetated hillslopes
Authors: Roth Danica L. , Doane Tyler H. , Roering Joshua J. , Furbish David J. , Zettler-Mann Aaron
Published: September 2020

Significance

Commonly used sediment transport models are fundamentally unable to account for long-distance particle motions characteristic of steep regions. This type of transport is a primary cause of elevated erosion rates after wildfire and may even contribute to postfire debris flows in some areas. Here we show that the incineration of vegetation causes measurable changes in surface roughness that drastically increase particle travel distances. Our data demonstrate that long-distance particle motion falls into three distinct regimes along a continuum that can be systematically represented by a simple model that scales with surface slope, roughness, and particle size. These results represent a key first-order step toward accounting for the effects of surface roughness on long-distance transport when predicting postfire and steepland erosion.
EPSIN1 and MTV1 define functionally overlapping but molecularly distinct
trans
-Golgi network subdomains in
Arabidopsis
Authors: Heinze Laura , Freimuth Nina , Rößling Ann-Kathrin , Hahnke Reni , Riebschläger Sarah , Fröhlich Anja , Sampathkumar Arun , McFarlane Heather E. , Sauer Michael
Published: September 2020

Significance

This is a comprehensive study of Epsin-like accessory proteins in
Arabidopsis
, for which so far only limited data are available. We identify two members as major accessory proteins at the TGN, controlling vacuolar and a subset of secretory transport. By interaction studies with AP complexes, genetic interactions, and enhanced-resolution microscopy, our work reveals the existence of two independent, parallel transport pathways, which originate from spatially separate regions at the TGN. Our study thus provides strong molecular, cellular, and genetic evidence for spatially, functionally, and molecularly separate subdomains of the plant TGN.
Matched-filter coding of sky polarization results in an internal sun compass in the brain of the desert locust
Authors: Zittrell Frederick , Pfeiffer Keram , Homberg Uwe
Published: September 2020

Significance

Many animals rely on the sun as a reference during spatial orientation. Insects can also use the pattern of polarization of the sky, generated by scattering of sunlight, as a guiding cue. We show here that certain neurons in the protocerebral bridge of the brain of the desert locust encode particular sun positions by responding best to a pattern of polarization generated by those sun positions. Across the protocerebral bridge, these neurons are arranged in a topographic, 360° compass with respect to angular orientation to the sun. This polarization-based compass is in line with a previously reported compass based on direct sunlight. Therefore, direct sunlight and whole-sky polarization complement each other in head direction coding in the locust.
Coronavirus hemagglutinin-esterase and spike proteins coevolve for functional balance and optimal virion avidity
Authors: Lang Yifei , Li Wentao , Li Zeshi , Koerhuis Danielle , van den Burg Arthur C. S. , Rozemuller Erik , Bosch Berend-Jan , van Kuppeveld Frank J. M. , Boons Geert-Jan , Huizinga Eric G. , van der Schaar Hilde M. , de Groot Raoul J.
Published: September 2020

Significance

Human coronavirus OC43 arose relatively recently, presumably from a bovine coronavirus spillover. Both viruses use 9-
O
-acetylated sialoglycans as receptors to which they attach via spike protein S. Another envelope protein, hemagglutinin-esterase (HE), serves as a receptor-destroying enzyme. We demonstrate that HE and S are functionally intertwined and that receptor destruction and receptor binding need to be carefully balanced for efficient (pre)attachment. During early emergence of OC43 this balance was reset, presumably as an adaptation to the human host. Such a two-protein mechanism for dynamic virion attachment is unique among coronaviruses, but reminiscent of that of influenza A viruses. Apparently, general principles fundamental to virion–sialoglycan interactions prompted convergent evolution of two zoonotically-relevant groups of pathogens.
Characterization and engineering of a two-enzyme system for plastics depolymerization
Authors: Knott Brandon C. , Erickson Erika , Allen Mark D. , Gado Japheth E. , Graham Rosie , Kearns Fiona L. , Pardo Isabel , Topuzlu Ece , Anderson Jared J. , Austin Harry P. , Dominick Graham , Johnson Christopher W. , Rorrer Nicholas A. , Szostkiewicz Caralyn J. , Copié Valérie , Payne Christina M. , Woodcock H. Lee , Donohoe Bryon S. , Beckham Gregg T. , McGeehan John E.
Published: September 2020

Significance

Deconstruction of recalcitrant polymers, such as cellulose or chitin, is accomplished in nature by synergistic enzyme cocktails that evolved over millions of years. In these systems, soluble dimeric or oligomeric intermediates are typically released via interfacial biocatalysis, and additional enzymes often process the soluble intermediates into monomers for microbial uptake. The recent discovery of a two-enzyme system for polyethylene terephthalate (PET) deconstruction, which employs one enzyme to convert the polymer into soluble intermediates and another enzyme to produce the constituent PET monomers (MHETase), suggests that nature may be evolving similar deconstruction strategies for synthetic plastics. This study on the characterization of the MHETase enzyme and synergy of the two-enzyme PET depolymerization system may inform enzyme cocktail-based strategies for plastics upcycling.
Distinct RNA
N-
demethylation pathways catalyzed by nonheme iron ALKBH5 and FTO enzymes enable regulation of formaldehyde release rates
Authors: Toh Joel D. W. , Crossley Steven W. M. , Bruemmer Kevin J. , Ge Eva J. , He Dan , Iovan Diana A. , Chang Christopher J.
Published: September 2020

Significance

Nonheme iron enzymes FTO and ALKBH5 play central roles in epigenetic RNA regulation by catalyzing the oxidation of
N
6-methyladenosine (m6A) to produce
N
6-hydroxymethyladenosine (hm6A) and adenosine (A), respectively. Here, we provide a mechanistic rationale for these distinct biochemical outcomes by identifying that ALKBH5 performs m6A demethylation via an unprecedented covalent-based mechanism with concomitant and rapid release of A and formaldehyde (FA), whereas FTO liberates hm6A to release A and FA over longer timescales. This work reveals foundational biochemical differences between these closely related but nonredundant epigenetic enzymes and identifies ALKBH5 as an endogenous source of rapid formaldehyde generation in cells.
Single-nucleus transcriptome analysis reveals dysregulation of angiogenic endothelial cells and neuroprotective glia in Alzheimer’s disease
Authors: Lau Shun-Fat , Cao Han , Fu Amy K. Y. , Ip Nancy Y.
Published: September 2020

Significance

Alzheimer’s disease (AD) has complex pathological mechanisms. Our limited understanding of the molecular and cellular changes in AD hindered the identification of therapeutic targets. In this study, we profiled 169,496 nuclei from the prefrontal cortical samples of AD patients and healthy controls by single-nucleus RNA sequencing. The results indicated that there is a loss of neuroprotective glial cells in AD, which may contribute to impaired neurotransmitter recycling in astrocytes, demyelination in oligodendrocytes, and perturbed synaptic pruning in microglia. Moreover, the analysis revealed a role of antigen presentation by angiogenic endothelial cells in AD. Together, our findings offer important insights into the therapeutic potential of targeting glial- and endothelial-specific pathways to restore brain homeostasis in AD.
Nonlinear Cauchy problem and identification in contact mechanics: a solving method based on Bregman-gap
Authors: Andrieux S , Baranger T N
Published: September 2020

This paper proposes a solution method for identification problems in the context of contact mechanics when overabundant data are available on a part Γ
m
of the domain boundary while data are missing from another part of this boundary. The first step is then to find a solution to a Cauchy problem. The method used by the authors for solving Cauchy problems consists of expanding the displacement field known on Γ
m
toward the inside of the solid via the minimization of a function that measures the gap between solutions of two well-posed problems, each one exploiting only one of the superabundant data. The key question is then to build an appropriate gap functional in strongly nonlinear contexts. The proposed approach exploits a generalization of the Bregman divergence, using the thermodynamic potentials as generating functions within the framework of generalized standard materials (GSMs), but also implicit GSMs in order to address Coulomb friction. The robustness and efficiency of the proposed method are demonstrated by a numerical bi-dimensional application dealing with a cracked elastic solid with unilateral contact and friction effects on the crack’s lips.
High-speed spatial encoding of modulated pump–probe signals with slow area detectors
Authors: Schick Daniel , Steinbach Felix , Noll Tino , Strüber Christian , Engel Dieter , von Korff Schmising Clemens , Pfau Bastian , Eisebitt Stefan
Published: September 2020

Most of today’s pump–probe experiments, which rely on two-dimensional detectors, suffer from low read-out rates that prevent the implementation of fast lock-in techniques to increase the signal-to-noise ratio. The first cameras running at true kHz-frame rates are available at large-scale facilities, but require sophisticated data management strategies. Here we present a scheme for high-speed spatial encoding of modulated pump–probe signals using slow area detectors at full repetition rate of a laser system without an increase in data rate or change of the sample environment. Towards that end we block the probe light in front of the detector alternatingly with two inverted masks at the same frequency as the signal is modulated, e.g. the chopping frequency of the pump light. Modulation frequencies up to 500 Hz are demonstrated using a commercial mechanical chopper and have been applied to a time-resolved Faraday microscopy experiment probing all-optical magnetic switching of a GdFe-alloy with femtosecond temporal resolution. We believe that our concept bridges the gap between today’s slow area detectors and the upcoming generation of true kHz-frame-rate cameras.
In-situ electrical conductance measurement of suspended ultra-narrow graphene nanoribbons observed via transmission electron microscopy
Authors: Liu Chunmeng , Zhang Jiaqi , Zhang Xiaobin , Muruganathan Manoharan , Mizuta Hiroshi , Oshima Yoshifumi
Published: September 2020

Graphene nanoribbon is an attractive material for nano-electronic devices, as their electrical transport performance can be controlled by their edge structures. However, in most cases, the electrical transport has been investigated only for graphene nanoribbons fabricated on a substrate, which hinders the appearance of intrinsic electrical transport due to screening effects. In this study, we developed special devices based on silicon chips for transmission electron microscopy to observe a monolayer graphene nanoribbon suspended between two gold electrodes. Moreover, with the development of an in-situ transmission electron microscopy holder, the current–voltage characteristics were achieved simultaneously with observing and modifying the structure. We found that the current–voltage characteristics differed between 1.5 nm-wide graphene nanoribbons with armchair and zigzag edge structures. The energy gap of the zigzag edge was more than two-fold larger than that of the armchair edge and exhibited an abrupt jump above a critical bias voltage in the differential conductance curve. Thus, our in-situ transmission electron microscopy method is promising for elucidating the structural dependence of electrical conduction in two-dimensional materials.
Fast and efficient nanoparticle trapping using plasmonic connected nanoring apertures
Authors: Bouloumis Theodoros D , Kotsifaki Domna G , Han Xue , Chormaic Síle Nic , Truong Viet Giang
Published: September 2020

The manipulation of microparticles using optical forces has led to many applications in the life and physical sciences. To extend optical trapping towards the nano-regime, in this work we demonstrate trapping of single nanoparticles in arrays of plasmonic coaxial nano-apertures with various inner disk sizes and theoretically estimate the associated forces. A high normalized experimental trap stiffness of 3.50 fN nm−1 mW−1
μm−2 for 20 nm polystyrene particles is observed for an optimum design of 149 nm for the nanodisk diameter at a trapping wavelength of 980 nm. Theoretical simulations are used to interpret the enhancement of the observed trap stiffness. A quick particle trapping time of less than 8  s is obtained at a concentration of 14 × 1011 particles ml−1 with low incident laser intensity of 0.59 mW μm−2. This good trapping performance with fast delivery of nanoparticles to multiple trapping sites emerges from a combination of the enhanced electromagnetic near-field and spatial temperature increase. This work has applications in nanoparticle delivery and trapping with high accuracy, and bridges the gap between optical manipulation and nanofluidics.
Synthesis and antimicrobial properties of CaCO3-nAg and nAg-CaCO3 nanocomposites
Authors: Długosz Olga , Lis Kinga , Banach Marcin
Published: September 2020

The nanocomposites of nAg-CaCO3 and CaCO3-nAg with different mass content of silver nanoparticles were obtained in a two-stage continuous microwave process. The nanocomposites were characterized by XRD, TEM, UV–vis, and FTIR spectroscopy. The effects of microwave radiation, silver nanoparticles content in the composite and the molar ratio of tannic acid to silver on the size of salt crystallites were studied. The effectiveness of combining silver nanoparticles with CaCO3 was confirmed to exceed 99%. Depending on the input parameters applied, the size of salt crystals in nAg/CaCO3 nanocomposites ranged from 25 to 45 nm, while the size of salt crystals in CaCO3/nAg nanocomposites ranged from 26 to 41 nm. In addition, some of the compositions were tested for their antimicrobial activity on selected yeast and bacterial microorganisms. The prepared materials present a biocidal effect, which makes them suitable for use in antimicrobial preparations.
Nanocluster glass-formation: a potential energy landscape perspective
Authors: Sun D Y , Gong X G
Published: September 2020

The intrinsic nature of glass states or glass transitions has been a mystery for a long time. Recent studies have suggested that glass-formation versus crystallization occurs for potential energy landscapes (PEL) having a specific structure and the present work is an elaboration of this perspective. To explore how the flatness of the PEL related to glass transition, we develop a method to adjust the PEL in a controllable manner. We demonstrate that a relatively flat PEL is not only necessary but also sufficient for the formation of a nanoscale glass. We show that: (1) as long as a nanocluster is located in a region of PEL with local minimum deep enough, it can undergo an abrupt thermodynamic transition reminiscent of the first order transition of bulk materials; and (2) if a nanocluster is located in a relatively flat PEL, it can undergo a very broad transition in their dynamics and thermodynamics that resembles glass-formation in bulk materials in many ways. All these transitions are independent of its structure symmetry, order or disorder. Our simulations also uncover the direct transition from one potential energy minimum to another below the glass transition temperature, which is the consequence of flat PELs.
Effect of surface modification and H2 reduction of WO3 nanoparticles in Methylene Blue photodegradation
Authors: Siddique Fizza , Gonzalez-Cortes Sergio , Xiao Tiancun , Rafiq M A , Edwards Peter P
Published: September 2020

We report the chemical synthesis of WO3 nanoparticles, PtOx–WO3 nanoparticles and Pt–WO3 nanoparticles with an average particle size of 20 nm. X-ray diffraction confirmed the formation of crystalline nanoparticles and the transmission electron microscope (TEM) images clearly show the presence of elemental Pt on WO3 nanoparticles (NPs). Moreover, Energy Dispersive x-ray spectroscopy (EDX) and Raman spectroscopy confirm the presence of Pt on the surface of WO3 NPs. The bandgap of WO3, PtOx–WO3 and Pt–WO3 was 2.78 eV, 2.59 eV and 2.28 eV respectively as determined by UV visible (UV–vis) spectroscopy. The H2-Temperature Programme Reduction (TPR) of WO3 and PtOx–WO3 NPs confirms the increase in interaction of H2 with PtOx–WO3 NPs. The photocatalytic performance of WO3 NPs, PtOx–WO3 NPs and Pt–WO3 NPs was investigated for Methylene Blue (MB) degradation. Samples of PtOx–WO3 showed higher photocatalytic rate for MB degradation than WO3 NPs. Importantly, a further increase in MB degradation efficiency was observed using Pt–WO3 NPs photocatalyst. Apparent reaction rate constants ‘kapp’ for MB degradation, calculated from a Langmuir model are 0.003 ± 0.001 min−1, 0.018 ± 0.003 min−1 and 0.040 ± 0.001 min−1 for WO3, PtOx–WO3 and Pt–WO3 NPs photocatalyst respectively. The increase in the degradation performance was attributed to surface defects and surface generation of oxygen vacancies during H2 reduction. The Pt–WO3 NPs exhibited 94.7 ± 0.6% Safranin-O (SO) degradation in 80 min and in this case the

k

a
p
p

0.027 ± 0.001 min−1.
Impact of RBC Transfusion on Peripheral Capillary Oxygen Saturation and Partial Pressure of Arterial Oxygen
Authors: Turgeman Alexa , McRae Hannah L , Cahill Christine , Blumberg Neil , Refaai Majed A
Published: September 2020

Objectives

RBCs are known to undergo deleterious changes during storage, known as storage lesions, which have been shown to result in decreased oxygen-carrying capacity. However, there is inadequate literature describing the effects of stored RBC allogeneic transfusion on oxygen parameters in vivo. The oxygen standard parameters were retrospectively assessed before and after RBC transfusion.

Methods

Patients who received 1 RBC transfusion were assessed for hemoglobin (Hb) levels, peripheral capillary oxygen saturation (Spo2), and partial pressure of arterial oxygen (Pao2) from 12 hours before and 24 hours after transfusion.

Results

In total, 78 patients who were monitored by Spo2 and 28 patients monitored by Pao2 were included in this analysis. Following RBC transfusion, Hb levels increased significantly (P < .001); however, there was a significant decrease in both Spo2 and Pao2 within 24 hours after transfusion (P = .04 and P = .003, respectively), indicating lower tissue oxygenation and lower soluble oxygen level.

Conclusions

This single-center, retrospective study revealed evidence of significantly decreased oxygenation and tissue perfusion after single-unit RBC transfusion, despite corrected Hb levels.
Childhood Exposure to Low to Moderate Doses of Ionizing Radiation and the Risk of Vascular Diseases
Authors: Sadetzki Siegal , Chetrit Angela , Boursi Ben , Luxenburg Osnat , Novikov Ilya , Cohen Arnon
Published: September 2020

In the Tinea Capitis Study (Israel, 1966–2011), we assessed the association between childhood exposure to low to moderate doses of ionizing radiation (IR) to the head and neck and the development of vascular diseases (ischemic heart disease, carotid artery stenosis, and stroke) in adulthood. The study included 17,734 individuals from the Tinea Capitis cohort (7,408 irradiated in childhood and 10,326 nonirradiated), insured by Israel’s largest health provider. Individual dosimetry was estimated based on measurements made on a head phantom and original treatment records. The mean doses were 1.5, 0.09, 0.78, and 0.017 Gy to brain, thyroid, salivary gland, and breast, respectively. Data on vascular diseases was abstracted from computerized medical records. Using Poisson regressions, we examined the association of radiation with morbidity. Any vascular disease was reported for 2,221 individuals. Adjusted for age, sex, socioeconomic status, smoking, hypertension, and diabetes, exposure to IR increased the risk of developing any vascular diseases (relative risk (RR) = 1.19, 95% confidence interval (CI): 1.09, 1.29), stroke (RR = 1.35, 1.20, 1.53), carotid artery stenosis (RR = 1.32, 1.06, 1.64), and ischemic heart disease (RR = 1.12, 1.01, 1.26). The risk of developing vascular diseases was positively associated with dose and inversely associated with age at exposure. In conclusion, the results indicate that early exposure to low to moderate doses of IR increases the risk of cerebro- and cardiovascular impairments.
Environmental complexity during early life shapes average behavior in adulthood
Authors: Xu Wenjiu , Yao Qi , Zhang Wenwen , Zhang Feng , Li Haifeng , Xu Renxin , Li Chunlin , Zhang Baowei
Published: September 2020

Personality has been identified in a range of animal taxa during the last few decades, with important ecological and evolutionary implications. Investigating the effects of environmental factors during early life can provide important insights into the ontogeny of animal personality. We reared newborn mosquitofish, Gambusia affinis, in tanks of different structural complexities, and measured their behavioral traits (i.e., shyness, exploration, and sociability) when they reached sexual maturity. Univariate linear mixed-effects models were fitted to test the effects of environmental complexity and sex on population-average behavior, whereas multivariate models were fitted to quantify behavioral repeatability (i.e., personality) and among-individual correlations (i.e., behavioral syndromes). On average, females were shyer and more social than males, and the fish reared in complex environments were shyer, less explorative, and more social than those reared in open environments. Among-individual differences were consistently large across trials for all behaviors, indicating that personality variation was present in mosquitofish of both sexes reared in different environments. Repeatability did not differ among behaviors, and there were no differences in repeatability in any behavior between sexes or among environments. A negative correlation between shyness and exploration was found in mosquitofish from all treatments at both phenotypic and among-individual levels, with the latter indicating a strong shyness–exploration behavioral syndrome. Our study provides robust evidence that average levels of personality might vary when mosquitofish are raised in different levels of structural complexity during early life.
QAlign: aligning nanopore reads accurately using current-level modeling
Authors: Joshi Dhaivat , Mao Shunfu , Kannan Sreeram , Diggavi Suhas
Published: September 2020

Motivation

Efficient and accurate alignment of DNA/RNA sequence reads to each other or to a reference genome/transcriptome is an important problem in genomic analysis. Nanopore sequencing has emerged as a major sequencing technology and many long-read aligners have been designed for aligning nanopore reads. However, the high error rate makes accurate and efficient alignment difficult. Utilizing the noise and error characteristics inherent in the sequencing process properly can play a vital role in constructing a robust aligner. In this article, we design QAlign, a pre-processor that can be used with any long-read aligner for aligning long reads to a genome/transcriptome or to other long reads. The key idea in QAlign is to convert the nucleotide reads into discretized current levels that capture the error modes of the nanopore sequencer before running it through a sequence aligner.

Results

We show that QAlign is able to improve alignment rates from around 80% up to 90% with nanopore reads when aligning to the genome. We also show that QAlign improves the average overlap quality by 9.2, 2.5 and 10.8% in three real datasets for read-to-read alignment. Read-to-transcriptome alignment rates are improved from 51.6% to 75.4% and 82.6% to 90% in two real datasets.

Availability and implementation

https://github.com/joshidhaivat/QAlign.git.

Supplementary information

Supplementary data are available at Bioinformatics online.
Being Visible in the Policy Process: The Experience of the School of Social Work at Addis Ababa University
Authors: Baynesagn Ashenafi Hagos
Published: September 2020

Social work faculty regularly encourage students to engage in policy practice, often structuring course assignments to allow students to apply their social work knowledge and skills to the policy process. Faculty members, as part of the expectation that they engage in community service, often are themselves involved with community groups, agencies, organisations and government bodies to develop, revise and evaluate policies to promote social and economic justice. Less is known about how social work education programmes, as organisations, work to fulfil the profession’s expectations and mandates regarding promoting more just policies and programmes. Hence, qualitative data were collected from twenty participants, forty-nine documents and more than seventy email conversations to understand the experience of School of Social Work at Addis Ababa University. The School’s experience offers an example of how an educational enterprise using its faculty members can be involved in policy practice. This article identifies various activities in which the School has been involved over the past fifteen years as well as the challenges and benefits of being engaged in these forms of policy practice.
Wound healing center establishment and new technology application in improving the wound healing quality in China
Authors: Fu Xiaobing
Published: September 2020

Wound healing, tissue repair and regenerative medicine are in great demand, and great achievements in these fields have been made. In recent years, many of these successes have benefitted patients, especially in the field of chronic skin wounds. However, perfect tissue repair and regeneration of damaged tissues and organs are still great challenges in the management of trauma and diseases. In this paper, the main achievements in wound healing, tissue repair and regeneration in China are reviewed and the establishment of wound healing centers and new technology application in improving wound healing quality in patients in China is highlighted.
Advancing a Dual-Process Model to Explain Interpersonal Versus Intergroup Communication in Social Media
Authors: Hinck Alexandra S , Carr Caleb T
Published: September 2020

Existing theories within interpersonal (IPC) and intergroup communication (IGC) have not yet explained when online interactions are initially intergroup in nature, interpersonal, or both. We address this undertheorized conundrum—which is particularly challenging as more communication occurs on social media, in which a multitude of goals may converge—by proposing the dual-process model of interpersonal–intergroup communication (IPC–IPG). Focusing on both the situation and a multiple goals perspective, this model can help explain where on the interpersonal–intergroup continuum online interactions fall. The ability to understand and articulate the antecedents and processes that may guide initial interactions can enhance future work by providing a mechanism through which to theorize which set(s) of theory may be most applicable to explain or predict a communicative situation and its outcomes.