bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrostatic pressure effect on metallic glasses: A theoretical prediction
Authors: Zhou Zhukun , Wang Hao , Li Mo
Published: October 2019

Metallic glasses are topologically disordered down to the atomic scales. As a result, during mechanical deformation there are random atomic displacements which necessarily lead to the volume change. Although volume dilatation has been observed, its contribution to the mechanical deformation and the pressure sensitivity in the yielding and fracture strengths remains controversial; since volume is the thermodynamic conjugate variable to the hydrostatic pressure, the volume change must be accompanied by certain degrees of pressure sensitivity. However, among the available measurements, a negligible effect of pressure on the yielding and fracture strengths is reported. Here, we try to understand this exceptional case. By using a finite deformation theory, we analyze the pressure effect on metallic glasses simultaneously subject to a pure shear and an applied hydrostatic pressure. We show that the shear deformation does couple to pressure, which is manifested through a strong dependence of the shear strength on pressure. We argue that the tendency of the deformation localization and the omnipresent sample imperfections may be responsible for the discrepancy between the available experimental results and our theoretical predictions.
Mercury-indium-sulfide nanocrystals: A new member of the family of ternary in based chalcogenides
Authors: Stroyuk Oleksandr , Raevskaya Alexandra , Spranger Felix , Selyshchev Oleksandr , Dzhagan Volodymyr , Solonenko Dmytro , Gaponik Nikolai , Zahn Dietrich R. T. , Eychmüller Alexander
Published: October 2019

A general synthesis approach of aqueous glutathione-capped ternary Ag–In–S, Cu–In–S, and Hg–In–S nanocrystals (NCs) is introduced, allowing the NC composition to be varied in a broad range. Ternary Hg–In–S (HIS) NCs are reported for the first time and found to have the same tetragonal chalcopyrite motif as Cu–In–S and Ag–In–S NCs, corroborated by phonon spectra, while X-ray photoelectron spectroscopic data indicate mercury to be present as Hg+ in the Hg–In–S NCs. Colloidal HIS and Hg–In–S/ZnS NCs showed little or no variations of the spectral width of the photoluminescence band upon NC size selection, temperature variation in a broad range of 10–350 K, deposition of a ZnS shell, or postsynthesis annealing. All these observations are similar to those reported earlier for Ag–In–S and Ag–In–S/ZnS NCs and allowed us to assume a general photoluminescence mechanism for all three ternary compounds, based on the model of radiative self-trapped exciton recombination.
Observation and theoretical analysis of near-infrared luminescence from CVD grown lanthanide Er doped monolayer MoS2 triangles
Authors: Lyu Yongxin , Wu Zehan , Io Weng Fu , Hao Jianhua
Published: October 2019

The near-infrared (NIR) emission of Er3+ ions has been extensively studied owing to their significance in optical communication applications. However, studies concerning the incorporation of lanthanide ions into the two-dimensional (2D) matrix are still in the early stages. In this work, we developed an ingenious two-step vapor-phase-transfer method to synthesize Er3+ doped MoS2 single-crystalline monolayers. The NIR emission at 1530 nm was observed from the doped MoS2 nanosheets under 980 nm diode laser excitation, corresponding to the energy transition from 4I13/2 to 4I11/2 of the Er3+ dopant. The concentration quenching effect was demonstrated with an optimal Er content of around 4 mol. %. To further understand the effect of lanthanide doping on the 2D MoS2 host matrix in terms of the growth mechanism and electronic structures, theoretical analysis was performed on Er-doped monolayer MoS2 using the density functional theory calculation. The computed band structure with the superimposed Dieke diagram was in good accordance with our experimental results. Our work offers the possibility to develop doping strategies in the 2D limit and provides an in-depth understanding of the lanthanide doping in atomically thin materials.
Ultrafast acoustic phonon scattering in CH3NH3PbI3 revealed by femtosecond four-wave mixing
Authors: March Samuel A. , Riley Drew B. , Clegg Charlotte , Webber Daniel , Hill Ian G. , Yu Zhi-Gang , Hall Kimberley C.
Published: October 2019

Carrier scattering processes are studied in CH3NH3PbI3 using temperature-dependent four-wave mixing experiments. Our results indicate that scattering by ionized impurities limits the interband dephasing time (T2) below 30 K, with strong electron-phonon scattering dominating at higher temperatures (with a time scale of 125 fs at 100 K). Our theoretical simulations provide quantitative agreement with the measured carrier scattering rate and show that the rate of acoustic phonon scattering is enhanced by strong spin-orbit coupling, which modifies the band-edge density of states. The Rashba coefficient extracted from fitting the experimental results (γc = 2 eV Å) is in agreement with calculations of the surface Rashba effect and recent experiments using the photogalvanic effect on thin films.
Model reconstruction from temporal data for coupled oscillator networks
Authors: Panaggio Mark J. , Ciocanel Maria-Veronica , Lazarus Lauren , Topaz Chad M. , Xu Bin
Published: October 2019

In a complex system, the interactions between individual agents often lead to emergent collective behavior such as spontaneous synchronization, swarming, and pattern formation. Beyond the intrinsic properties of the agents, the topology of the network of interactions can have a dramatic influence over the dynamics. In many studies, researchers start with a specific model for both the intrinsic dynamics of each agent and the interaction network and attempt to learn about the dynamics of the model. Here, we consider the inverse problem: given data from a system, can one learn about the model and the underlying network? We investigate arbitrary networks of coupled phase oscillators that can exhibit both synchronous and asynchronous dynamics. We demonstrate that, given sufficient observational data on the transient evolution of each oscillator, machine learning can reconstruct the interaction network and identify the intrinsic dynamics.
Triplet vs πσ* state mediated N–H dissociation of aniline
Authors: Jhang Wan Ru , Lai Hsin Ying , Lin Yen-Cheng , Lee Chin , Lee Shih-Huang , Lee Yin-Yu , Ni Chi-Kung , Tseng Chien-Ming
Published: October 2019

UV-excited aromatic molecules with N–H/O–H moieties often possess an important nonradiative relaxation pathway, from an optically bright ππ* state to a dark dissociative πσ* state. We apply a new time-selected photofragment translational spectroscopy method to disclose a previously unknown triplet-mediated N–H dissociation of aniline prevented by the multiphoton dissociative ionization in conventional methods. We further determined the branching fractions of aniline dissociated in the πσ*, triplet, and ground states at 248 nm. Additionally, we selectively captured the population changes in the singlet and triplet states with ionization from different laser wavelengths, 355 or 266 nm, in time-resolved photoion yields. The combination of experimental data enables us to uniquely determine the relative ionization cross sections of the singlet and triplet states at an ionization laser wavelength of 266 nm and allows us to extensively measure the rate constants of intersystem crossing and the branching fractions at various excitation wavelengths.
Metalorganic-aerosol-deposited Au nanoparticles for the characterization of ultrathin films by surface-enhanced Raman spectroscopy
Authors: Merten S. , Roddatis V. , Moshnyaga V.
Published: October 2019

An alternative approach for ultrathin film characterization by means of Surface-Enhanced Raman Spectroscopy was realized and applied to the characterization of nanocrystalline TiO2 films. The vacuum-free metalorganic aerosol deposition (MAD) technique was used to grow gold nanoparticles onto the surface of thin TiO2 films. An averaged enhancement factor of 107, as well as the characterization of a 3 nm thin film, was accomplished. Since the thin film acts as a substrate itself, this technique can be used for the characterization of a variety of solid thin film materials. Furthermore, MAD-based nanoparticle growth can be of special interest for oxide films due to the high oxygen partial pressure and the constant oxygen flow during the deposition.
An efficient spectral method for numerical time-dependent perturbation theory
Authors: Lavigne Cyrille , Brumer Paul
Published: October 2019

We develop the Fourier-Laplace Inversion of the Perturbation Theory (FLIPT), a novel numerically exact “black box” method to compute perturbative expansions of the density matrix with rigorous convergence conditions. Specifically, the FLIPT method is extremely well-suited to simulate multiphoton pulsed laser experiments with complex pulse shapes. The n-dimensional frequency integrals of the nth order perturbative expansion are evaluated numerically using tensor products. The N-point discretized integrals are computed in O(N2) operations, a significant improvement over the O(Nn) scaling of standard quadrature methods.
Advances in simulations of moving striations in DC discharges of noble gases
Authors: Arslanbekov Robert R. , Kolobov Vladimir I.
Published: October 2019

We describe the results of two-dimensional self-consistent simulations of moving striations in DC discharges of noble gases for both diffuse and constricted plasma regimes. We use a fluid plasma model capturing key physics and change only one control parameter (volume recombination rate) to describe both the diffuse and constricted plasma. The newly developed implicit coupled plasma solver with an adaptive Cartesian mesh enables us to obtain for the first time the two-dimensional structure of the entire cathode-to-anode discharge and self-excited nonlinear ionization waves in the constricted plasmas. The results are in agreement with the previously developed linear theory of striations in constricted discharges.
Study of nonlinear optical properties of TiO2 – polystyrene nanocomposite films
Authors: Zeinali M. , Jaleh B. , Rashidian Vaziri M.R. , Omidvar A.
Published: October 2019

We consider an ex-situ prepared TiO2 − polystyrene (TiO2 − PS) nanocomposite, with different concentration of TiO2 nanoparticles (NPs), deposited by the spin-coating method on quartz substrates. Nonlinear optical properties of the TiO2 − PS nanocomposite films are studied using the Z-scan technique. Structural properties of the films are investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements. The optical band gap energy of the TiO2 − PS films are determined from the optical absorption spectra. The relation between the optical nonlinearities and the bandgap energy, as a microscopic electronic property of the semiconductor nanocomposite, is established. It is shown that an increase in the content of TiO2 NPs in the nanocomposite films results in bandgap narrowing and concomitant enhancement of optical nonlinearities. It is proposed that bandgap narrowing and enhancement of optical nonlinearities can be ascribed to the introduction of mid-gap states as a result of the formation of surface defects in TiO2 NPs. The results of this work indicate that incorporation of TiO2 NPs in the PS polymeric matrix can be a new way for bandgap narrowing of TiO2 NPs toward the visible light region, which is of great interest for their application in this part of the spectrum. Furthermore, enhancement of the optical nonlinearities of the spin-coated TiO2 − PS films by increasing the TiO2 NP content can open up new avenues for their use as nonlinear optical films in photonics applications.
Asymptotic theory of ponderomotive dynamics of an electron in the field of a focused relativistically intense electromagnetic envelope
Authors: Shiryaev O.B.
Published: October 2019

Based on a formal asymptotic solution of Maxwell’s equations for a field propagating in a vacuum and of the relativistic Newton equation for an electron driven by the corresponding Lorentz force, we construct a description of the relativistic ponderomotive dynamics of an electron in the field of an intense focused electromagnetic envelope. A small parameter for the asymptotic expansion is proportional to the ratio of the radiation wavelength to the focal spot radius. Using the obtained averaged model of ponderomotive dynamics, electron beam scattering patterns are plotted with regard to an angle relative to the electromagnetic field propagation axis for laser pulses with a Gaussian transverse intensity distribution, as well as the energy spectra of scattered electrons corresponding to individual ranges of this angle. Scattered particles are absent in some ranges of the polar angle.
Population gratings produced in a quantum system by a pair of sub-cycle pulses
Authors: Arkhipov R.M. , Arkhipov M.V. , Pakhomov A.V. , Rosanov N.N.
Published: October 2019

Possible generation of light-induced harmonic population gratings in a quantum system by two half-cycle pulses is studied using the approximate solution of the Schrödinger equation. The case is considered where the duration of pulses is shorter than the resonance transition periods in the system and the pulses do not overlap in the medium. The grating modulation depth is determined by the pulse electric area.
Attainment of a 40 TW peak output power with a visible-range hybrid femtosecond laser system
Authors: Alekseev S.V. , Ivanov N.G. , Losev V.F. , Mesyats G.A. , Mikheev L.D. , Ratakhin N.A. , Panchenko Yu.N.
Published: October 2019

We report the results of investigations aimed at raising the peak output power of a THL-100 visible-range hybrid femtosecond laser system based on a XeF(C − A) photodissociation amplifier. The increase in power was achieved due to the shortening of the pulse duration at the system output by broadening the spectral profile of the second harmonic from 5.3 to 8 nm, which takes place in the transformation of a negatively chirped pulse of the fundamental frequency radiation in a nonlinear KDP crystal. After the KDP the radiation pulse was stretched to 1.8 ps in a prism stretcher and amplified in the XeF(C − A) amplifier. The energy obtained at the amplifier output was 1.2 J. After compression of the amplified output pulse, its duration was equal to 29.4 fs, which means that a peak output power of 40 TW was reached at the output of the laser system.
All-fibre single-mode small-signal amplifier operating near 0.976 μm
Authors: Aleshkina S.S. , Lipatov D.S. , Kochergina T.A. , Velmiskin V.V. , Temyanko V.L. , Kotov L.V. , Bardina T.L. , Bubnov M.M. , Guryanov A.N. , Likhachev M.E.
Published: October 2019

We have developed and demonstrated a polarisation-maintaining single-mode ytterbium-doped fibre for light amplification at a wavelength near 0.976 μm in an all-fibre configuration. A distinctive feature of the proposed fibre design is low losses due to fusion splices with standard single-mode fibre having a core diameter of 10 μm, which has made it possible to produce an all-fibre small-signal amplifier with a gain threshold near 3 W and a differential pump-to-signal conversion efficiency of 9.8 % in the saturation regime. The proposed amplifier has been shown to be well-suited for small-signal amplification. In particular, at an input signal power near 1 mW and a gain of 20 dB, the ratio of the amplified signal to the integrated luminescence intensity near 0.976 μm exceeds 20 dB. A 40-dB gain has been demonstrated for an ultrasmall signal of ∼10-μW power.
Phase locking of a diode bar using a phase diffraction mirror
Authors: Derzhavin S.I. , Lyndin N.M. , Timoshkin V.N.
Published: October 2019

A method for synchronising the emission of a laser diode bar using a phase diffraction mirror is proposed. It is confirmed experimentally that this method makes it possible to phase the bar emission, but its selective properties are insufficient to ensure stable single-mode lasing.
Dynamics of living cells in a cytomorphological state space
Authors: Chang Amy Y. , Marshall Wallace F.
Published: October 2019

Significance

The cell is where life emerges from nonliving matter. How can we understand the behavior of a complicated, far-from-equilibrium system such as a living cell? By defining a state space for cells and analyzing state transitions, we find that cell behavior can be successfully predicted by an effective potential function, which suggests that although cells are complex nonequilibrium systems, this complexity can be reduced to a simple equilibrium function for predicting cell behavior.
The capping enzyme facilitates promoter escape and assembly of a follow-on preinitiation complex for reinitiation
Authors: Fujiwara Rina , Damodaren Nivedita , Wilusz Jeremy E. , Murakami Kenji
Published: October 2019

Significance

After RNA synthesis is initiated by RNA polymerase II (pol II) and general transcription factors (GTFs), pol II dissociates from GTFs and promoter DNA and undergoes the transition to productive elongation. This transition is generally referred to as promoter escape and is a major rate-limiting step at many mRNA genes, but key details have remained unclear. We have developed an in vitro reconstituted transcription system that has high initiation efficiency, which allowed us to dissect the timing of this transition. We found that the formation of the initially transcribing complex, containing pol II, general transcription factors, and a nascent transcript, is long persisting and that 2 elongation factors conserved across eukaryotes have robust and positive biochemical activities on this transition.
Expanding the stoichiometric window for metal cross-linked gel assembly using competition
Authors: Cazzell Seth Allen , Holten-Andersen Niels
Published: October 2019

Polymer networks with dynamic cross-links have generated widespread interest as tunable and responsive viscoelastic materials. However, narrow stoichiometric limits in cross-link compositions are typically imposed in the assembly of these materials to prevent excess free cross-linker from dissolving the resulting polymer networks. Here we demonstrate how the presence of molecular competition allows for vast expansion of the previously limited range of cross-linker concentrations that result in robust network assembly. Specifically, we use metal-coordinate cross-linked gels to verify that stoichiometric excessive metal ion cross-linker concentrations can still result in robust gelation when in the presence of free ion competing ligands, and we offer a theoretical framework to describe the coupled dynamic equilibria that result in this effect. We believe the insights presented here can be generally applied to advance engineering of the broadening class of polymer materials with dynamic cross-links.
Sublethal antibiotics collapse gut bacterial populations by enhancing aggregation and expulsion
Authors: Schlomann Brandon H. , Wiles Travis J. , Wall Elena S. , Guillemin Karen , Parthasarathy Raghuveer
Published: October 2019

Antibiotics induce large and highly variable changes in the intestinal microbiome even at sublethal concentrations, through mechanisms that remain elusive. Using gnotobiotic zebrafish, which allow high-resolution examination of microbial dynamics, we found that sublethal doses of the common antibiotic ciprofloxacin cause severe drops in bacterial abundance. Contrary to conventional views of antimicrobial tolerance, disruption was more pronounced for slow-growing, aggregated bacteria than for fast-growing, planktonic species. Live imaging revealed that antibiotic treatment promoted bacterial aggregation and increased susceptibility to intestinal expulsion. Intestinal mechanics therefore amplify the effects of antibiotics on resident bacteria. Microbial dynamics are captured by a biophysical model that connects antibiotic-induced collapses to gelation phase transitions in soft materials, providing a framework for predicting the impact of antibiotics on the intestinal microbiome.
Cryptic diversity of a widespread global pathogen reveals expanded threats to amphibian conservation
Authors: Byrne Allison Q. , Vredenburg Vance T. , Martel An , Pasmans Frank , Bell Rayna C. , Blackburn David C. , Bletz Molly C. , Bosch Jaime , Briggs Cheryl J. , Brown Rafe M. , Catenazzi Alessandro , Familiar López Mariel , Figueroa-Valenzuela Raul , Ghose Sonia L. , Jaeger Jef R. , Jani Andrea J. , Jirku Miloslav , Knapp Roland A. , Muñoz Antonio , Portik Daniel M. , Richards-Zawacki Corinne L. , Rockney Heidi , Rovito Sean M. , Stark Tariq , Sulaeman Hasan , Tao Nguyen Thien , Voyles Jamie , Waddle Anthony W. , Yuan Zhiyong , Rosenblum Erica Bree
Published: October 2019

Biodiversity loss is one major outcome of human-mediated ecosystem disturbance. One way that humans have triggered wildlife declines is by transporting disease-causing agents to remote areas of the world. Amphibians have been hit particularly hard by disease due in part to a globally distributed pathogenic chytrid fungus (
Batrachochytrium dendrobatidis
[
Bd
]). Prior research has revealed important insights into the biology and distribution of
Bd
; however, there are still many outstanding questions in this system. Although we know that there are multiple divergent lineages of
Bd
that differ in pathogenicity, we know little about how these lineages are distributed around the world and where lineages may be coming into contact. Here, we implement a custom genotyping method for a global set of
Bd
samples. This method is optimized to amplify and sequence degraded DNA from noninvasive skin swab samples. We describe a divergent lineage of
Bd
, which we call
Bd
ASIA3, that appears to be widespread in Southeast Asia. This lineage co-occurs with the global panzootic lineage (
Bd
GPL) in multiple localities. Additionally, we shed light on the global distribution of
Bd
GPL and highlight the expanded range of another lineage,
Bd
CAPE. Finally, we argue that more monitoring needs to take place where
Bd
lineages are coming into contact and where we know little about
Bd
lineage diversity. Monitoring need not use expensive or difficult field techniques but can use archived swab samples to further explore the history—and predict the future impacts—of this devastating pathogen.
Metasurface-generated complex 3-dimensional optical fields for interference lithography
Authors: Kamali Seyedeh Mahsa , Arbabi Ehsan , Kwon Hyounghan , Faraon Andrei
Published: October 2019

Significance

Fast submicrometer-scale 3D printing techniques are of interest for various applications ranging from photonics and electronics to tissue engineering. Interference lithography is a versatile 3D printing method with the ability to generate complicated nanoscale structures. Its application, however, has been hindered by either the complicated setups in multibeam lithography that cause sensitivity and impede scalability or the limited level of control over the fabricated structure achievable with mask-assisted processes. Here, we show that metasurface masks can generate complex volumetric intensity distributions with submicrometer scales for fast and scalable 3D printing. These results push the limits of optical devices in controlling the light intensity distribution and significantly increase the realm of possibilities for 3D printing.
L-type voltage-gated Ca2+channel CaV1.2 regulates chondrogenesis during limb development
Authors: Atsuta Yuji , Tomizawa Reiko R. , Levin Michael , Tabin Clifford J.
Published: October 2019

All cells, including nonexcitable cells, maintain a discrete transmembrane potential (Vmem), and have the capacity to modulateVmemand respond to their own and neighbors’ changes inVmem. Spatiotemporal variations have been described in developing embryonic tissues and in some cases have been implicated in influencing developmental processes. Yet, how such changes inVmemare converted into intracellular inputs that in turn regulate developmental gene expression and coordinate patterned tissue formation, has remained elusive. Here we document that theVmemof limb mesenchyme switches from a hyperpolarized to depolarized state during early chondrocyte differentiation. This change inVmemincreases intracellular Ca2+signaling through Ca2+influx, via CaV1.2, 1 of L-type voltage-gated Ca2+channels (VGCCs). We find that CaV1.2 activity is essential for chondrogenesis in the developing limbs. Pharmacological inhibition by an L-type VGCC specific blocker, or limb-specific deletion of CaV1.2, down-regulates expression of genes essential for chondrocyte differentiation, includingSox9,Col2a1, andAgc1, and thus disturbs proper cartilage formation. The Ca2+-dependent transcription factor NFATc1, which is a known major transducer of intracellular Ca2+signaling, partly rescues Sox9 expression. These data reveal instructive roles of CaV1.2 in limb development, and more generally expand our understanding of how modulation of membrane potential is used as a mechanism of developmental regulation.
Fitness effects but no temperature-mediated balancing selection at the polymorphic
Adh
gene of
Drosophila melanogaster
Authors: Siddiq Mohammad A. , Thornton Joseph W.
Published: October 2019

Significance

What factors maintain genetic variation in natural populations? Opposing selection pressures on protein stability and catalytic activity are thought to maintain variation along thermal gradients in many enzymes. We examined a classic hypothesis of temperature-mediated balancing selection, the alcohol dehydrogenase enzyme of
Drosophila melanogaster
, in which 2 latitudinally distributed variants are thought to be maintained by an activity/stability trade-off. Using in vitro and in vivo assays and population genetic analyses, we found no evidence of the predicted biochemical or fitness trade-offs and no signature of balancing selection. Rather, one variant confers greater activity and survival in the presence of ethanol, irrespective of temperature. Variation in
Adh,
and possibly other enzymes, must therefore be caused by other factors correlated with temperature.
Skeletal MyBP-C isoforms tune the molecular contractility of divergent skeletal muscle systems
Authors: Li Amy , Nelson Shane R. , Rahmanseresht Sheema , Braet Filip , Cornachione Anabelle S. , Previs Samantha Beck , O’Leary Thomas S. , McNamara James W. , Rassier Dilson E. , Sadayappan Sakthivel , Previs Michael J. , Warshaw David M.
Published: October 2019

Significance

Myosin-binding protein C (MyBP-C) is a critical component of the skeletal muscle sarcomere, muscle’s smallest contractile unit. MyBP-C’s importance is evident by genetic mutations leading to human myopathies, such as distal arthrogryposis (i.e., club foot). However, the molecular basis of MyBP-C’s functional impact on skeletal muscle contractility is far from certain. Complicating matters further is the expression of fast- and slow-type MyBP-C isoforms that depend on whether the muscle is fast- or slow-twitch. Using multiscale proteomic, biophysical, and mathematical modeling approaches, we defined the expression, localization, and modulatory capacities of these distinct skeletal MyBP-C isoforms in rat skeletal muscles. Each MyBP-C isoform modulates muscle contractility differentially, providing the capacity to fine-tune a muscle’s mechanical performance as physiological demands arise.
A multifunctional shape-morphing elastomer with liquid metal inclusions
Authors: Ford Michael J. , Ambulo Cedric P. , Kent Teresa A. , Markvicka Eric J. , Pan Chengfeng , Malen Jonathan , Ware Taylor H. , Majidi Carmel
Published: October 2019

Significance

Research in soft robotics and wearable technologies has led to increasing demand for shape-changing materials that can be powered with portable electronics. Liquid crystal elastomers (LCEs) are a promising functional material for these applications but lack the electrical and thermal conductivity required for electrically stimulated shape-memory activation. To address this, LCEs are typically embedded with rigid fillers that enhance conductivity. However, these particles degrade the mechanical properties and shape-morphing capabilities of the LCE matrix. Here, we overcome these limitations with an advanced material architecture in which rigid filler is replaced with deformable liquid metal inclusions. This results in LCE composites that exhibit a combination of high electrical conductivity, high thermal conductivity, and actuation capabilities unlike any other soft composite.
ScreeningLegionellaeffectors for antiviral effects reveals Rab1 GTPase as a proviral factor coopted for tombusvirus replication
Authors: Inaba Jun-ichi , Xu Kai , Kovalev Nikolay , Ramanathan Harish , Roy Craig R. , Lindenbach Brett D. , Nagy Peter D.
Published: October 2019

Significance

Many bacterial pathogens infect eukaryotic cells by injecting bacterial virulence factors or effectors into the cytosol of their hosts. These effector proteins have evolved to manipulate cellular pathways and favor bacterial replication.Legionella pneumophila, the cause of Legionnaires’ disease, synthesizes >300 effector proteins. Here, we screenedLegionellaeffectors to probe tombusvirus (TBSV)–host interactions and identify antiviral factors against TBSV in yeast surrogate host. As proof of concept that bacterial effectors can be used as tools to identify cellular pathways used by viruses, we characterized the antiviral effect of DrrA effector ofLegionella. This led to the discovery that Rab1 small GTPase, the cellular target of DrrA, and COPII vesicles are coopted by TBSV for building the viral replication compartment.
Preoperative metabolic classification of thyroid nodules using mass spectrometry imaging of fine-needle aspiration biopsies
Authors: DeHoog Rachel J. , Zhang Jialing , Alore Elizabeth , Lin John Q. , Yu Wendong , Woody Spencer , Almendariz Christopher , Lin Monica , Engelsman Anton F. , Sidhu Stan B. , Tibshirani Robert , Suliburk James , Eberlin Livia S.
Published: October 2019

Thyroid neoplasia is common and requires appropriate clinical workup with imaging and fine-needle aspiration (FNA) biopsy to evaluate for cancer. Yet, up to 20% of thyroid nodule FNA biopsies will be indeterminate in diagnosis based on cytological evaluation. Genomic approaches to characterize the malignant potential of nodules showed initial promise but have provided only modest improvement in diagnosis. Here, we describe a method using metabolic analysis by desorption electrospray ionization mass spectrometry (DESI-MS) imaging for direct analysis and diagnosis of follicular cell-derived neoplasia tissues and FNA biopsies. DESI-MS was used to analyze 178 tissue samples to determine the molecular signatures of normal, benign follicular adenoma (FTA), and malignant follicular carcinoma (FTC) and papillary carcinoma (PTC) thyroid tissues. Statistical classifiers, including benign thyroid versus PTC and benign thyroid versus FTC, were built and validated with 114,125 mass spectra, with accuracy assessed in correlation with clinical pathology. Clinical FNA smears were prospectively collected and analyzed using DESI-MS imaging, and the performance of the statistical classifiers was tested with 69 prospectively collected clinical FNA smears. High performance was achieved for both models when predicting on the FNA test set, which included 24 nodules with indeterminate preoperative cytology, with accuracies of 93% and 89%. Our results strongly suggest that DESI-MS imaging is a valuable technology for identification of malignant potential of thyroid nodules.
IL-10–producing B cells are enriched in murine pericardial adipose tissues and ameliorate the outcome of acute myocardial infarction
Authors: Wu Lan , Dalal Rajeev , Cao Connie D. , Postoak J. Luke , Yang Guan , Zhang Qinkun , Wang Zhizhang , Lal Hind , Van Kaer Luc
Published: October 2019

Significance

Myocardial infarction (MI) remains a leading cause of mortality and morbidity worldwide. Although it is recognized that a balanced and timely terminated proinflammatory response following acute MI is essential in promoting tissue repair/regeneration, the underlying regulatory mechanisms are poorly defined. In this report, we show that IL-10–producing B cells in mice: 1) Are enriched in pericardial adipose tissues (PATs) and influenced by cytokines preferentially expressed in these tissues; 2) expand in PATs following MI and accumulate in the infarcted heart during the resolution of MI-induced inflammation; and 3) facilitate resolution of inflammation and reduce myocardial injury to preserve cardiac function after MI. These findings identify IL-10–producing B cells, in particular those in PATs, as therapeutic targets for MI.
An ensemble of flexible conformations underlies mechanotransduction by the cadherin–catenin adhesion complex
Authors: Bush Martin , Alhanshali Bashir M. , Qian Shuo , Stanley Christopher B. , Heller William T. , Matsui Tsutomu , Weiss Thomas M. , Nicholl Iain D. , Walz Thomas , Callaway David J. E. , Bu Zimei
Published: October 2019

Significance

Adherens junctions are specialized cell–cell adhesion complexes found in epithelial, endothelial, and neuronal tissues of multicellular organism. The cadherin–catenin complex is the core component of the adherens junction and transmits mechanical stress from cell to cell. This study reveals that the cadherin–catenin complex displays a wide spectrum of flexible structures, which suggests a dynamic mechanism for this complex in mechanotransduction for cell–cell adhesion.
Ultrasensitive, multiplexed chemoproteomic profiling with soluble activity-dependent proximity ligation
Authors: Li Gang , Eckert Mark A. , Chang Jae Won , Montgomery Jeffrey E. , Chryplewicz Agnieszka , Lengyel Ernst , Moellering Raymond E.
Published: October 2019

Significance

We report the development of a chemical proteomic platform, soluble activity-dependent proximity ligation (sADPL), which enables ultrasensitive and multiplexed quantification of endogenous active proteins in complex proteome samples from cells, fluids, and tissues. Single-plexed and multiplexed sADPL can be implemented to “write” and “read” barcoded oligonucleotide amplicons derived from specific active enzymes in extremely low levels of whole proteome. We apply sADPL to quantify in vivo protein–drug interactions from blood samples, as well as perform hundreds to thousands of parallel activity measurements in fresh or flash-frozen patient tumor samples in a matter of hours on a benchtop. Combined, these studies provide compelling proof-of-concept examples for future applications for the molecular analysis of biological and clinical samples.
Complete cleavage of the N≡N triple bond by Ta2N+via degenerate ligand exchange at ambient temperature: A perfect catalytic cycle
Authors: Geng Caiyun , Li Jilai , Weiske Thomas , Schwarz Helmut
Published: October 2019

Significance

Catalysts accelerate chemical reactions by opening energetically favorable pathways. Although catalytic processes are ubiquitous, the actual catalytically active species often remain elusive due to their very nature. The interaction between the catalyst and the substrate is usually fast, and the rather short-lived intermediates are difficult to identify. As a catalytically active species, Ta2N+was discovered. This tiny “molecular machine” cleaves the very strong N2triple bond and reassembles it at ambient temperature. As the N2unit, which is liberated during the process, contains the nitrogen atom of Ta2N+, this reaction serves as a rare gas-phase example for the operation of the Mars/van Krevelen mechanism, which itself belongs to the basic concepts of heterogenous catalysis.
Experience-dependent structural plasticity at pre- and postsynaptic sites of layer 2/3 cells in developing visual cortex
Authors: Sun Yujiao Jennifer , Espinosa J. Sebastian , Hoseini Mahmood S. , Stryker Michael P.
Published: October 2019

The developing brain can respond quickly to altered sensory experience by circuit reorganization. During a critical period in early life, neurons in the primary visual cortex rapidly lose responsiveness to an occluded eye and come to respond better to the open eye. While physiological and some of the molecular mechanisms of this process have been characterized, its structural basis, except for the well-known changes in the thalamocortical projection, remains obscure. To elucidate the relationship between synaptic remodeling and functional changes during this experience-dependent process, we used 2-photon microscopy to image synaptic structures of sparsely labeled layer 2/3 neurons in the binocular zone of mouse primary visual cortex. Anatomical changes at presynaptic and postsynaptic sites in mice undergoing monocular visual deprivation (MD) were compared to those in control mice with normal visual experience. We found that postsynaptic spines remodeled quickly in response to MD, with neurons more strongly dominated by the deprived eye losing more spines. These postsynaptic changes parallel changes in visual responses during MD and their recovery after restoration of binocular vision. In control animals with normal visual experience, the formation of presynaptic boutons increased during the critical period and then declined. MD affected bouton formation, but with a delay, blocking it after 3 d. These findings reveal intracortical anatomical changes in cellular layers of the cortex that can account for rapid activity-dependent plasticity.
Verbal working memory as a predictor of explicit and implicit knowledge of English passive voice
Authors: Pawlak Mirosław , Biedroń Adriana
Published: October 2019

While there is copious evidence concerning the effectiveness of different instructional options in teaching
grammar (e.g., Nassaji, 2017; Pawlak, 2017),
less is known about the extent to which the contribution of pedagogical intervention is mediated by individual factors. The same
can be said about the product of instructed but also uninstructed second language acquisition, that is the knowledge of target
language grammar. The paper attempts to shed light on one such variable, that is working memory, which has recently been an object
of intensive empirical inquiry (e.g., Li, 2017; Wen, Biedroń, & Skehan, 2016). It reports the results of a study that investigated the role of verbal working
memory in the development of explicit and implicit knowledge of the English passive voice. Participants were 156 Polish university
students enrolled in a three-year BA program in English. The data on verbal working memory were collected by means of the
Polish Listening Span Test (PLSPAN), developed by Zychowicz, Biedroń and
Pawlak (2017). Explicit knowledge was tapped by means of an untimed grammatically judgment test, which focused on
reception, and a traditional grammar test, which targeted production. Implicit knowledge was tapped through a timed grammaticality
judgment test for reception and a focused communication task (Ellis, 2003) for
production. Correlational analysis demonstrated that verbal working memory was a weak predictor of explicit productive and
receptive knowledge but not implicit knowledge.
Perspective: optically-pumped III–V quantum dot microcavity lasers via CMOS compatible patterned Si (001) substrates
Authors: Wei Wenqi , Feng Qi , Wang Zihao , Wang Ting , Zhang Jianjun
Published: October 2019

Direct epitaxial growth III–V quantum dot (QD) structures on CMOS-compatible silicon substrates is considered as one of the most promising approaches to achieve low-cost and high-yield Si-based lasers for silicon photonic integration. However, epitaxial growth of III–V materials on Si encounters the following three major challenges: high density of threading dislocations, antiphase boundaries and thermal cracks, which significantly degrade the crystal quality and potential device performance. In this review, we will focus on some recent results related to InAs/GaAs quantum dot lasers on Si (001) substrates by III–V/IV hybrid epitaxial growth via (111)-faceted Si hollow structures. Moreover, by using the step-graded epitaxial growth process the emission wavelength of InAs QDs can be extended from O-band to C/L-band. High-performance InAs/GaAs QD micro-disk lasers with sub-milliwatts threshold on Si (001) substrates are fabricated and characterized. The above results pave a promising path towards the on-chip lasers for optical interconnect applications.
Recent advances of heterogeneously integrated III–V laser on Si
Authors: Guo Xuhan , He An , Su Yikai
Published: October 2019

Due to the indirect bandgap nature, the widely used silicon CMOS is very inefficient at light emitting. The integration of silicon lasers is deemed as the ‘Mount Everest’ for the full take-up of Si photonics. The major challenge has been the materials dissimilarity caused impaired device performance. We present a brief overview of the recent advances of integrated III–V laser on Si. We will then focus on the heterogeneous direct/adhesive bonding enabling methods and associated light coupling structures. A selected review of recent representative novel heterogeneously integrated Si lasers for emerging applications like spectroscopy, sensing, metrology and microwave photonics will be presented, including DFB laser array, ultra-dense comb lasers and nanolasers. Finally, the challenges and opportunities of heterogeneous integration approach are discussed.
III–V compound materials and lasers on silicon
Authors: Yang Wenyu , Li Yajie , Meng Fangyuan , Yu Hongyan , Wang Mengqi , Wang Pengfei , Luo Guangzhen , Zhou Xuliang , Pan Jiaoqing
Published: October 2019

Silicon-based photonic integration has attracted the interest of semiconductor scientists because it has high luminous efficiency and electron mobility. Breakthroughs have been made in silicon-based integrated lasers over the past few decades. Here we review three main methods of integration of III–V materials on Si, namely direct growth, bonding, and selective-area hetero-epitaxy. The III–V materials we introduced mainly include materials such as GaAs and InP. The lasers are mainly lasers of related communication bands. We also introduced the advantages and challenges of the three methods.
Dynamics of InAs/GaAs quantum dot lasers epitaxially grown on Ge or Si substrate
Authors: Wang Cheng , Zhou Yueguang
Published: October 2019

Growing semiconductor laser sources on silicon is a crucial but challenging technology for developing photonic integrated circuits (PICs). InAs/GaAs quantum dot (Qdot) lasers have successfully circumvented the mismatch problem between III–V materials and Ge or Si, and have demonstrated efficient laser emission. In this paper, we review dynamical characteristics of Qdot lasers epitaxially grown on Ge or Si, in comparison with those of Qdot lasers on native GaAs substrate. We discuss properties of linewidth broadening factor, laser noise and its sensitivity to optical feedback, intensity modulation, as well as mode locking operation. The investigation of these dynamical characteristics is beneficial for guiding the design of PICs in optical communications and optical computations.
Synthesis, characterization, fabrication and application of electrospun nanofiber polymer composite: a potential bio-material for black mold rot (Aspergillus niger) of onions (Allium cepa L.)
Authors: De La Rama EM , Lavarias J , Monserate J
Published: October 2019

Nanomaterial is widely researched because of its enormous potential. In this study, the anti-fungal activity of electrospun nanofiber polymer composites infused with malunggay extracts (ME) was investigated. Cellulose acetate (CA) from abaca fiber, nano silica (nSiO2) from rice husks, and nano copper oxide nCuO from cavendish banana peel were synthesized, characterized and used as stabilizing agent. Electrospun nanofiber polymer composites infused with malunggay extracts was successfully fabricated. The inhibitory effects of the fabricated nanofiber were determined using different concentrations of ME. Results showed that 100 % concentration of malunggay extract (ME) mixed with 50 mg of nSiO2 and 50 mg of nCuO) had a presence of small crystal-like structures that indicates the successful infusion of the bio-materials. The nanofibers showed inhibitory effect against A. niger both in in vitro and in vivo. It displayed the highest zone of inhibition, lowest weight loss and disease severity index which is comparable to the fungicide. This study confirms the antifungal potential of the Electrospun nanofiber polymer composites infused with malunggay extracts on the test fungi and suggests the possibility of employing them in food preservation were spoilage is mainly caused by A. niger.
On the Role of Plasmonic Nanoparticles on the Photocatalytic of TiO2 Nanoparticles for Visible-Light Photoreduction of Bicarbonate
Authors: Khalil Munawar , Mulyanto Muhammad Fariz , Gunlazuardi Jarnuzi
Published: October 2019

The potential application of anatase titanium dioxide (TiO2) nanoparticles for solar fuel generation has been recently attracting many attentions due to its excellent chemical stability. Nevertheless, the fast charge recombination during photoexcitation process may often reduce the photocatalytic activity. This work presents the role of plasmonic Au nanoparticles on enhancing the photocatalytic activity of TiO2 nanoparticles for a visible-light-driven conversion of bicarbonate to formate. Here, two types of nano-sized Au and TiO2 heterostructures, i.e., Au-TiO2 Janus nanostructures and core-shell Au@TiO2 nanostructures were successfully prepared and characterized using UV-Vis and HR-TEM. Results demonstrated that Au-TiO2 Janus nanostructures had a superior photocatalytic activity compared to TiO2 nanoparticles and core-shell Au@TiO2 nanostructures. This photocatalytic enhancement is believed due to the presence of surface plasmon resonance (SPR) phenomenon in Au nanoparticles that provides a Fermi energy level, which could prevent the charge recombination process during photoexcitation.
Mechanical properties and morphology of electrospun mats made of poly (ω-pentadecalactone)
Authors: Pavlova E R , Nifant’ev I E , Minyaev M E , Bagrov D V , Klinov D V
Published: October 2019

Electrospinning of biodegradable poly(ω-pentadecalactone) (PPDL) is poorly investigated. In the present work, PPDL homopolymers of different molecular weight were synthesized by ring-opening polymerization of ωPDL, and then electrospun. Mixtures of PPDL with hexafluoro-2-propanol (HFIP) and with HFIP-chloroform blend were used for electrospinning. Since PPDL is poorly soluble in HFIP at high concentrations, the PPDL-HFIP mixture was turbid and its electrospinning led to heterogeneous mats. Addition of 30% of chloroform to the PPDL-HFIP mixture turned it into a transparent solution. After electrospinning, the PPDL-HFIP-chloroform mixtures yielded mats, which consisted of flat and round fibers with a wrinkled surface. The flat fibers (ribbons) were observed more frequently when the PPDL sample with the highest molecular weight was electrospun. All the obtained electrospun mats demonstrated high elongation at break (from 150% to 350%). In our future research, these mats will be examined as biomaterials.