bluuebunny/crossref_metadata_2025 huggingface dataset:
Anisotropic epsilon-near-pole (ENP) resonance leads to hyperbolic photonic dispersion in homologous (Bi2)m(Bi2Se3)n topological quantum materials
Authors: Maurya Krishna Chand , Bhui Animesh , Biswas Kanishka , Saha Bivas
Published: July 2021

The hyperbolic iso-frequency surface (dispersion) of photons in materials that arise from extreme dielectric anisotropy is the latest frontier in nanophotonics with potential applications in subwavelength imaging, coherent thermal emission, photonic density of state engineering, negative refraction, thermal hyperconductivity, etc. Most hyperbolic materials utilize nanoscale periodic metal/dielectric multilayers (superlattices) or metallic nanowires embedded inside the dielectric matrix that require expensive growth techniques and possess significant fabrication challenges. Naturally occurring bulk materials that exhibit tunable hyperbolic photonic dispersion in the visible-to-near-IR spectral ranges will, therefore, be highly beneficial for practical applications. Due to the layered structure and extreme anisotropy, a homologous series of (Bi2)m(Bi2Se3)n could serve as a unique class of natural hyperbolic material with tunable properties derived from different stoichiometry. In this Letter, we demonstrate hyperbolic photonic dispersion in a single crystal of weak topological insulator BiSe (m = 1 and n = 2), where a Bi2 layer is inserted between Bi2Se3 (m = 0 and n = 1) quintuple layers in the visible (525–710 nm) and near-UV (210–265 nm) spectral range. The origin of hyperbolic dispersion in homologous (Bi2)m(Bi2Se3)n topological quantum materials arises from their anisotropic epsilon-near-pole resonance corresponding to the interband transitions that lead to different signs of its dielectric permittivity. The tunability of hyperbolic dispersion is further demonstrated by alloying Bi2Se3 with Mn that alters the interband transition positions and expands their hyperbolic spectral regime from 500–1045 to 500–1185 nm.
Ultraviolet waveband vector beams generation assisted by the nonlinear frequency conversion
Authors: Li Hui , Liu Haigang , Yang Yangfeifei , Lu Ruifeng , Chen Xianfeng
Published: July 2021

Vector beams with a nonseparable polarization distribution are almost thoroughly studied from their generation to application in infrared and visible regimes. Until now, the nonlinear generation of ultraviolet vector beams is only focused on the nonlinear optical processes of gas molecules, which seriously impacts its further applications due to the unstable property. Here, we present a study on the generation of ultraviolet vector beams assisted by the nonlinear frequency conversion processes in potassium dihydrogen phosphate crystals. The vectorial properties of the generated ultraviolet waveband vector beams are characterized in both theoretical and experimental environments. The proposed method paves the way for the generation of extreme ultraviolet vector beams with solid-state nonlinear crystal, which is a more compact and stable way compared with the gas nonlinear method. This work also opens a route for photolithographic techniques and laser processing based on ultraviolet waveband vector beams.
Normally-off operations in partially-gate-recessed AlTiO/AlGaN/GaN field-effect transistors based on interface charge engineering
Authors: Nguyen Duong Dai , Isoda Takehiro , Deng Yuchen , Suzuki Toshi-kazu
Published: July 2021

We report normally-off operations in partially-gate-recessed AlxTiyO(AlTiO)/AlGaN/GaN metal-insulator-semiconductor (MIS) field-effect transistors (FETs), where aluminum titanium oxide AlTiO, an alloy of Al2O3 and TiO2, is employed as a gate insulator. Since AlTiO is useful for interface charge engineering owing to a trend that the AlTiO/AlGaN interface fixed charge is suppressed in comparison with Al2O3, we investigated combining the interface charge engineering with a partial gate recess method for AlTiO/AlGaN/GaN MIS-FETs. For AlTiO with a composition of x/(x+y)=0.73, a suppressed positive interface fixed charge at the AlTiO/recessed-AlGaN interface leads to a positive slope in the relation between the threshold voltage and the AlTiO insulator thickness. As a result, we successfully obtained normally-off operations in partially-gate-recessed AlTiO/AlGaN/GaN MIS-FETs with favorable performances, such as a threshold voltage of 1.7 V, an on-resistance of 9.5Ωmm, an output current of 450 mA/mm, a low sub-threshold swing of 65 mV/decade, and a rather high electron mobility of 730cm2/Vs. The results show that the interface charge engineering in combination with partial gate recess is effective for the GaN-based normally-off device technology.
On the modified Poisson–Boltzmann closure for primitive model electrolytes at high concentration
Authors: Outhwaite Christopher W. , Bhuiyan Lutful Bari
Published: July 2021

The modified Poisson–Boltzmann closure is applied to the Kirkwood hierarchy of integral equations to investigate high concentration primitive model electrolytes. Two approximations are considered in the two sphere fluctuation potential problem. The derived damped oscillatory mean electrostatic potentials suggest that this closure should be of use in providing a basis for understanding the large experimental decay lengths found at high electrolyte concentrations.
Coupled spin waves and crystalline electric field levels in candidate multiferroic ErFeO3
Authors: Zic Mark P. , Fuhrman Wesley T. , Wang Kefeng , Ran Sheng , Paglione Johnpierre , Butch Nicholas P.
Published: July 2021

We report an inelastic neutron scattering study of candidate multiferroic ErFeO3, a compound that has been previously reported to have three different magnetic states and undergoes signatures of Fe3+−Er3+ cooperative coupling. The spectrum at low energy transfer is dominated by excitations of the Er3+ character, even above the Er3+ antiferromagnetic ordering temperature of 4.5 K. In addition, a crystalline electric field excitation at 6 meV exhibits additional energy splitting upon cooling through 4.5 K with mode-dependent polarization. This indicates different moment directions for these modes, an interesting consequence of Cy ordering of the Er3+ moments.
Boosting alkaline water electrolysis by asymmetric temperature modulation
Authors: Zhu Qinpeng , Yang Peihua , Zhang Tao , Yu Zehua , Liu Kang , Fan Hong Jin
Published: July 2021

Hydrogen production by water electrolysis is a sustainable and promising pathway to store surplus electricity from intermittent renewable energy. In conventional electrolyzers, hydrogen evolution and oxygen evolution reactions at the two electrodes run at the same temperature. In this work, we implement an asymmetric temperature modulation to enhance the water electrolysis rate in an alkaline solution. We revisit the thermodynamics of water electrolysis and determine by both simulations and experiments that the Gibbs free energy change required for alkaline water electrolysis under asymmetric temperature is lower than that under uniform average temperature. With the temperature difference of 40 K (possible for low-grade waste heat), the required voltage of asymmetric configuration decreases by 100 mV at the current density of 10 mA cm−2 compared to the system operated at the same average temperature. Moreover, the thermal efficiency reaches a maximum value of 7% under optimized operating current density. The asymmetric-temperature water electrolysis opens a promising way for utilization of low-grade heat.
Exploring spin symmetry-breaking effects for static field ionization of atoms: Is there an analog to the Coulson–Fischer point in bond dissociation?
Authors: Cunha Leonardo A. , Lee Joonho , Hait Diptarka , McCurdy C. William , Head-Gordon Martin
Published: July 2021

Löwdin’s symmetry dilemma is an ubiquitous issue in approximate quantum chemistry. In the context of Hartree–Fock (HF) theory, the use of Slater determinants with some imposed constraints to preserve symmetries of the exact problem may lead to physically unreasonable potential energy surfaces. On the other hand, lifting these constraints leads to the so-called broken symmetry solutions that usually provide better energetics, at the cost of losing information about good quantum numbers that describe the state of the system. This behavior has previously been extensively studied in the context of bond dissociation. This paper studies the behavior of different classes of HF spin polarized solutions (restricted, unrestricted, and generalized) in the context of ionization by strong static electric fields. We find that, for simple two electron systems, unrestricted Hartree–Fock (UHF) is able to provide a qualitatively good description of states involved during the ionization process (neutral, singly ionized, and doubly ionized states), whereas RHF fails to describe the singly ionized state. For more complex systems, even though UHF is able to capture some of the expected characteristics of the ionized states, it is constrained to a single Ms (diabatic) manifold in the energy surface as a function of field intensity. In this case, a better qualitative picture can be painted by using generalized Hartree–Fock as it is able to explore different spin manifolds and follow the lowest solution due to lack of collinearity constraints on the spin quantization axis.
Crystallization mechanism and switching behavior of In–S–Sb phase change thin films
Authors: Wang Guoxiang , Liu Fen , Lu Yegang , Chen Yimin , Shen Xiang
Published: July 2021

The crystallization mechanism of In2S3-doped Sb thin films is studied in detail to verify the potential application in phase change memory. Here, we observe directly that two different crystallization behaviors can exist in In–S–Sb thin layers by using aberration-corrected scanning transmission electron microscopy. The difference between Sb53.3(In2S3)46.7 and Sb30.9(In2S3)69.1 materials is induced by phase separation. The crystallization mechanism of the Sb53.3(In2S3)46.7 material is related to the formation of the nanocomposite structure with continuous precipitation of Sb nanocrystals. The crystallization characteristic of the Sb30.9(In2S3)69.1 material originates from the diffusion-driven In–S/In–S–Sb interface formation that acts as a “n–p” heterojunction, thereby resulting in the “depletion layer effect” and decreasing the carrier density to 7.42 × 1020 cm−3 at 280 °C. Sb30.9(In2S3)69.1 shows good bipolar-type resistance switching characteristics as the conventional Ge2Sb2Te5. This work provides clear experimental evidence to deepen the understanding of the crystallization mechanism for indium chalcogenides alloyed with Sb films, contributing to the improved control of the phase change behavior to establish high-performance multi-level nonvolatile memory and neuromorphic synaptic systems.
Coupling the first and second attenuation zones in seismic metasurface
Authors: Zeng Yi , Cao Liyun , Zhu Yifan , Wang Yan-Feng , Du Qiu-Jiao , Wang Yue-Sheng , Assouar Badreddine
Published: July 2021

Semi-infinite elastic metamaterials and metasurfaces on homogeneous elastic half-spaces have attracted significant attention in the past two decades as efficient artificial structures to control and mitigate surface waves. In this research, the first two attenuation zones of an elastic metasurface composed of different arrangements of pillars on a substrate are investigated. First, the lowest frequency attenuation zone (LFAZ) is numerically investigated. Then, the rainbow trapping effect of the second attenuation zone (SAZ) is demonstrated by numerical simulations and experiments. The different characteristics of these two attenuation zones are brought together to connect the lower bound of the SAZ and the upper bound of the LFAZ, allowing to design a seismic metasurface that only uses one kind of artificial structure on a half-space to attenuate Rayleigh waves in the frequency range extending from 5 to 22 Hz.
Temperature enhanced responsivity and speed in an AlGaN/GaN metal-heterostructure-metal photodetector
Authors: Tang Xi , Ji Fengwei , Wang Huan , Jin Zijing , Li Hui , Li Baikui , Wang Jiannong
Published: July 2021

An AlGaN/GaN metal-heterostructure-metal (MHM) ultraviolet (UV) photodetector employing lateral Schottky contacts was fabricated and characterized at different temperatures. As the temperature increased from 25 to 250 °C, the photoresponsivity of the MHM photodetector increased 3.5 times. This was attributed to the spontaneous-polarization-induced spatial separation of the photogenerated electrons and holes and the increased optical absorption at higher temperatures. Meanwhile, the decay time constant of the photocurrent became approximately three orders of magnitude smaller. With the enhanced photoresponsivity and the decreased response time constant, kilohertz optical switching of the MHM photodetector was recorded at 250 °C. The AlGaN/GaN MHM photodetector, sharing the same GaN-on-Si electronics platform, provides an applicable candidate for an all-GaN integrated UV sensing and amplifying system for high-temperature applications.
Explicitly correlated Fock-space coupled-cluster singles and doubles method for (1,1), (0,2), and (2,0) sectors
Authors: Bokhan Denis , Bednyakov Alexander S. , Musiał Monika , Perera Ajith , Trubnikov Dmitrii N.
Published: July 2021

A linearly approximated explicitly correlated coupled-cluster singles and doubles model for the Fock-space coupled-cluster method has been formulated and implemented. An extension of the Fock-space wave operators is introduced in order to treat the short-range correlation effects for excited and doubly electron-attached states. We show that an effective reduction in the number of active virtuals can also be obtained by improving how the short-range correlation is treated. Numerical results to gauge the performance for valence and Rydberg excitation energies, double ionization potentials, and double electron attachment energies of several molecules are obtained. Statistical measures of the errors in excitation energies show that the explicitly correlated results are within 0.1 eV from the complete basis set limit already at the double-ζ level unless the excitation energies are too close to the ionization thresholds. Similar accuracy is seen for the double ionization potentials and double electron attachment energies.
Room temperature cavity electromechanics in the sideband-resolved regime
Authors: Le Anh Tuan , Brieussel A. , Weig E. M.
Published: July 2021

We demonstrate a sideband-resolved cavity electromechanical system operating at room temperature. It consists of a nanomechanical resonator, a strongly pre-stressed silicon nitride string, dielectrically coupled to a three-dimensional microwave cavity made of copper. The electromechanical coupling is characterized by two measurements, the cavity-induced eigenfrequency shift of the mechanical resonator and the optomechanically induced transparency. While the former is dominated by dielectric effects, the latter reveals a clear signature of the dynamical backaction of the cavity field on the resonator. This unlocks the field of cavity electromechanics for room temperature applications.
The relationship between charge and molecular dynamics in viscous acid hydrates
Authors: Ahlmann S. , Münzner P. , Moch K. , Sokolov A. P. , Böhmer R. , Gainaru C.
Published: July 2021

Oscillatory shear rheology has been employed to access the structural rearrangements of deeply supercooled sulfuric acid tetrahydrate (SA4H) and phosphoric acid monohydrate, the latter in protonated (PA1H) and deuterated (PA1D) forms. Their viscoelastic responses are analyzed in relation to their previously investigated electric conductivity. The comparison of the also presently reported dielectric response of deuterated sulfuric acid tetrahydrate (SA4D) and that of its protonated analog SA4H reveals an absence of isotope effects for the charge transport in this hydrate. This finding clearly contrasts with the situation known for PA1H and PA1D. Our analyses also demonstrate that the conductivity relaxation profiles of acid hydrides closely resemble those exhibited by classical ionic electrolytes, even though the charge transport in phosphoric acid hydrates is dominated by proton transfer processes. At variance with this dielectric simplicity, the viscoelastic responses of these materials depend on their structural compositions. While SA4H displays a “simple liquid”-like viscoelastic behavior, the mechanical responses of PA1H and PA1D are more complex, revealing relaxation modes, which are faster than their ubiquitous structural rearrangements. Interestingly, the characteristic rates of these fast mechanical relaxations agree well with the characteristic frequencies of the charge rearrangements probed in the dielectric investigations, suggesting appearance of a proton transfer in mechanical relaxation of phosphoric acid hydrates. These findings open the exciting perspective of exploiting shear rheology to access not only the dynamics of the matrix but also that of the charge carriers in highly viscous decoupled conductors.
Ostwald ripening under temperature gradient: A phase-field study
Authors: Yamada Ryo , Inubushi Haruki , Ohno Munekazu
Published: July 2021

Ostwald ripening under a temperature gradient in binary model alloys is investigated using a quantitative phase-field model. The simulations show that a cube of average radius of a second-phase particle is proportional to time, and the particle size distribution shows self-similarity in a steady state, as with a uniform temperature field. It is found that the growth rate of particles under a temperature gradient is faster than that in the isothermal case, and the steady-state particle size distribution depends on the magnitude of the temperature gradient. Furthermore, the second-phase particles migrate from low temperature regions to high temperature regions when a non-uniform temperature field is applied. The migration velocity of particles, averaged over the whole system, increases with the magnitude of the temperature gradient. On the other hand, the velocity of each particle is not relevant to particle size. Hence, the particle migration is entirely ascribed to the diffusion flux driven by the concentration gradient originating from the temperature dependence of solute solubility.
The influence of gas volume fractions on deformation and volumetric efficiency of twin-screw multiphase pump based on fluid–thermal–structure coupling numerical calculation
Authors: Zhang Xuejing , Yang Junhu , Ma Chong , Han Wei , Wei Deqiang , Lan Ting
Published: July 2021

The twin-screw multiphase pump shows a significant phenomenon of fluid–thermal–structure physics field coupling. The method of studying dynamics, thermodynamic characteristics, and deformation of the screw pump is biased from the actual boundary conditions without considering multi-field coupling. To enhance the calculation accuracy of the twin-screw pump integrated deformation field and further determine the clearances between rotors and pump liner, the fluid–thermal–structure coupling calculation is completed by ANSYS WORKBENCH. The calculation results of the leakage rate are verified by experiments. The moving reference frame dynamic mesh method is used in the fluid domain numerical simulation, and the non-equilibrium wall function method is used to solve the boundary layer. The rotor and pump liner deformations and their influences on volumetric efficiency are studied under different gas volume fractions. The optimal installation clearances are proposed to reduce the leakage flow rate and prevent the rotor from sticking due to large deformation. The results show that the calculated results of the leakage rate are in good agreement with the experimental values, and the average deviation is less than 4%. The research program effectively ensures the calculation accuracy and efficiency of the whole model and provides an important basis for the optimal design of the twin-screw pump.
Hybrid BaTiO3/SiNx/AlGaN/GaN lateral Schottky barrier diodes with low turn-on and high breakdown performance
Authors: Rahman Mohammad Wahidur , Chandrasekar Hareesh , Razzak Towhidur , Lee Hyunsoo , Rajan Siddharth
Published: July 2021

In this Letter, we demonstrate hybrid GaN lateral Schottky barrier diodes with enhanced breakdown characteristics and a low turn-on voltage. These diodes incorporate a lateral Schottky barrier in combination with a high permittivity material beneath the field plate, enabling high average breakdown fields and a low turn-on voltage. Average electric fields up to 2.38 MV/cm were achieved for devices with an anode–cathode spacing of 4 μm, while maintaining with a turn-on voltage of 0.48 V. In contrast, SiNx/AlGaN/GaN control lateral Schottky diodes displayed an average breakdown field of ∼0.7 MV/cm for devices with similar dimensions with a turn-on voltage of 0.46 V. The use of a high-permittivity dielectric can more effectively utilize the high breakdown fields in wide bandgap materials by proper management of the electric field. This demonstration provides an innovative way to integrate high-permittivity materials with GaN lateral devices for improved breakdown and resistance characteristics.
Magnetoelectric coupling in micropatterned BaTiO3/CoFe2O4 epitaxial thin film structures: Augmentation and site-dependency
Authors: Kim Donghoon , Rossell Marta D. , Campanini Marco , Erni Rolf , Puigmartí-Luis Josep , Chen Xiang-Zhong , Pané Salvador
Published: July 2021

The prominent magnetoelectric (ME) effect in ME composites usually originates from an interfacial strain-mediated coupling between ferroelectric and ferromagnetic components. While ME composite bilayer thin films have been proposed for microdevice applications, the ME coupling is usually diminished because of the substrate clamping effect. Here, we apply simple CMOS/MEMS compatible top-down fabrication techniques to ferroelectric BaTiO3 (BTO) and ferromagnetic CoFe2O4 (CFO) bilayer epitaxial thin films to control the substrate clamping. We found augmented ME coupling in micro-patterned bilayer thin films compared to the as-deposited films due to the reduced substrate clamping. In addition, a site-dependent ME coupling within the microstructure was observed. Larger ME coupling was obtained near the edge of the microstructure, and site-dependent ferroelectric imprints were observed on the micropattern. This can be attributed to the non-uniform substrate clamping across the film, and the strain gradient developed in the BTO layer due to the magnetostriction of CFO. Our findings provide additional insights to the design of micro- and nanoscale devices based on 2–2 ME composite thin films.
Highly conductive graphite matrix/copper composites by a pressureless infiltration method
Authors: Wei Wenfu , Li Xiaobo , Yang Zefeng , Huang Zhanglin , Zuo Haozi , Liao Qianhua , Xie Wenhan , Yin Guofeng , Wu Guangning
Published: July 2021

Graphite matrix/copper composites have found significant potential uses in numerous areas. Until now, a high ambient gas pressure has to be applied to overcome the non-wettability between the copper melt and graphite matrix, which has restricted the technological and economic efficiencies, as well as the composite performance. In this paper, we have proposed a pressureless infiltration strategy to realize the preparation of highly conductive graphite matrix/copper composites. A tungsten carbide network is first in situ constructed in the graphite matrix, transforming the capillary force from the resistance mode to the impetus mode. Results show that the contact angle of graphite/copper decreased from 138.5° to 23° due to the constructed tungsten carbide network. The composites exhibit good interfacial bonding, and the electrical conductivity reaches 15.1 × 105 S/m, far higher than the requirement of the industry standard.
Modeling non-linear dielectric susceptibilities of supercooled molecular liquids
Authors: Speck Thomas
Published: July 2021

Advances in high-precision dielectric spectroscopy have enabled access to non-linear susceptibilities of polar molecular liquids. The observed non-monotonic behavior has been claimed to provide strong support for theories of dynamic arrest based on the thermodynamic amorphous order. Here, we approach this question from the perspective of dynamic facilitation, an alternative view focusing on emergent kinetic constraints underlying the dynamic arrest of a liquid approaching its glass transition. We derive explicit expressions for the frequency-dependent higher-order dielectric susceptibilities exhibiting a non-monotonic shape, the height of which increases as temperature is lowered. We demonstrate excellent agreement with the experimental data for glycerol, challenging the idea that non-linear response functions reveal correlated relaxation in supercooled liquids.
Long-term switching of single photochromic triads based on dithienylcyclopentene and fluorophores at cryogenic temperatures
Authors: Maier Johannes , Weller Tina , Thelakkat Mukundan , Köhler Jürgen
Published: July 2021

Photochromic molecules can be reversibly converted between two bistable forms by light. These systems have been intensively studied for applications as molecular memories, sensing devices, or super-resolution optical microscopy. Here, we study the long-term switching behavior of single photochromic triads under oxygen-free conditions at 10 K. The triads consist of a photochromic unit that is covalently linked to two strong fluorophores that were employed for monitoring the light-induced conversions of the switch via changes in the fluorescence intensity from the fluorophores. As dyes we use either perylene bisimide or boron-dipyrromethen, and as photochromic switch we use dithienylcyclopentene (DCP). Both types of triads showed high fatigue resistance allowing for up to 6000 switching cycles of a single triad corresponding to time durations in the order of 80 min without deterioration. Long-term analysis of the switching cycles reveals that the probability that an intensity change in the emission from the dyes can be assigned to an externally stimulated conversion of the DCP (rather than to stochastic blinking of the dye molecules) amounts to 0.7 ± 0.1 for both types of triads. This number is far too low for optical data storage using single triads and implications concerning the miniaturization of optical memories based on such systems will be discussed. Yet, together with the high fatigue resistance, this number is encouraging for applications in super-resolution optical microscopy on frozen biological samples.
Effects of polymers on the cavitating flow around a cylinder: A large-scale molecular dynamics analysis
Authors: Asano Yuta , Watanabe Hiroshi , Noguchi Hiroshi
Published: July 2021

The cavitation flow of linear-polymer solutions around a cylinder is studied by performing a large-scale molecular dynamics simulation. The addition of polymer chains remarkably suppresses cavitation. The polymers are stretched into a linear shape near the cylinder and entrained in the vortex behind the cylinder. As the polymers stretch, the elongational viscosity increases, which suppresses the vortex formation. Furthermore, the polymers exhibit an entropic elasticity owing to stretching. This elastic energy increases the local temperature, which inhibits the cavitation inception. These effects of polymers result in the dramatic suppression of cavitation.
High photoluminescence from self-assembled Ag2Cl2(dppe)2 clusters through metallophilic interactions
Authors: Bootharaju Megalamane S. , Lee Sanghwa , Deng Guocheng , Chang Hogeun , Baek Woonhyuk , Hyeon Taeghwan
Published: July 2021

Ligand protected metal nanoclusters (NCs) are an emerging class of functional materials with intriguing photophysical and chemical properties. The size and molecular structure play an important role in endowing NCs with characteristic optical and electronic properties. Modulation of these properties through the chemical reactivity of NCs is largely unexplored. Here, we report on the synthesis of self-assembled Ag2Cl2(dppe)2 clusters through the ligand-exchange-induced transformation of [Pt2Ag23Cl7(PPh3)10] NCs [(dppe): 1,2-bis(diphenylphosphino)ethane; (PPh3): triphenylphosphine]. The single crystal x-ray structure reveals that two Ag atoms are bridged by one dppe and two Cl ligands, forming a Ag2Cl2(dppe) cluster, which is subsequently self-assembled through dppe ligands to form [Ag2Cl2(dppe)2]n. Importantly, the Ag2Cl2(dppe)2 cluster assembly exhibits high photoluminescence quantum yield: ∼18%, which is attributed to the metallophilic interactions and rigidification of the ligand shell. We hope that this work will motivate the exploitation of the chemical reactivity of NCs as a new path to attain cluster assemblies endowed with enhanced photophysical properties.
Near-optimal combination of high performance and insensitivity in a shock compressed high explosive single crystal
Authors: Winey J. M. , Toyoda Y. , Gupta Y. M.
Published: July 2021

Achieving the desired combination of superior detonation performance and insensitivity to shock initiation has been a long-standing goal in high explosive (HE) science and technology. Having previously established the shock insensitivity of 1,1-diamino-2,2-dinitroethene (also known as DADNE or FOX-7) single crystals to 20 GPa (extended to 25 GPa in this work), the FOX-7 detonation response was determined through wave profile measurements in ∼250 μm thick single crystals shock compressed to 64 GPa. Quite unexpectedly, FOX-7 demonstrated the classic Chapman–Jouguet (C–J) detonation response—reaction completion in the detonation front (<0.7 ns) at pressures of 44 GPa and higher—not observed in other insensitive high explosives. The experimentally determined C–J pressure (35 GPa), detonation wave velocities and the detonation products equation of state—together with shock insensitivity to 25 GPa—demonstrate that FOX-7 single crystals display a near-optimal combination of high performance and shock insensitivity, not observed in another HE crystal.
The hydrodynamics of an inertial squirmer rod
Authors: Ouyang Zhenyu , Lin Jianzhong
Published: July 2021

The hydrodynamic behavior of a two-dimensional elongated micro-swimmer (squirmer rod) in a bulk fluid is studied numerically with an immersed boundary-lattice Boltzmann method. The swimming Reynolds numbers, the number of the squirmers (squirmer is a self-propelled model to assemble the elongated micro-swimmer), and the relative distance between two adjacent squirmers' centers are, respectively, set being 0.05 ≤ Res ≤ 5, 2 ≤ i ≤ 8, and 0.75d ≤ s ≤ 1.5d (d is the diameter of the squirmer) to investigate the swimming speed, the power expenditure, and the hydrodynamic efficiency of the micro-swimmer. The results show that the swimming speed of the puller rod (a type of elongated micro-swimmers propelled from the front) increases monotonically with enhancing i. The pusher rod (a type of elongated micro-swimmers propelled from the rear) with more pushers i swims faster at Res ≤ 0.1, whereas it swims slower at Res > 0.1. The speed of the pusher rod increases monotonously with the decrease in the distance s, whereas a non-monotonous variation is found for the puller rod. Meanwhile, the more i or smaller s for the puller and pusher rods, the more power P they expend, and no appreciable distinction is found for their P at 0.05 ≤ Res ≤ 1. By continuing to increase Res (Res > 1), P increases monotonically for both the puller and pusher rods, and it is more appreciably for the pusher rods. Finally, the hydrodynamic efficiency η of the pusher rods increases monotonically with the translational Reynolds number ReU, in contrast to that of the puller rods, which decreases (ReU ≤ 1) and then increases (ReU > 1) with ReU. For the pusher rods at ReU > 1, the increasing ratio of η is proportional to ReU0.7. The higher η is found for the squirmer rods with smaller i or greater s.
Pickering emulsions: structure, properties and the use as colloidosomes and stimuli-sensitive emulsions
Authors: Koroleva M. Yu. , Yurtov E. V.
Published: July 2021

Pickering emulsions are emulsions that are stabilized by solid micro- and nanoparticles. These emulsions are in most demand for applications where the use of surfactants is restricted. The review addresses stabilization of Pickering emulsions. The attention is focused on the flocculation, coalescence, sedimentation and Ostwald ripening processes taking place in these emulsions. The structures formed by particles in the emulsion dispersion medium and in thin interlayers between the dispersed phase droplets are analyzed. Methods for preparing colloidosomes, that is, microcapsules of assembled particles, from Pickering emulsions are considered. Colloidosomes are promising for the encapsulation and prolonged release of active substances. Conversely, Pickering stimuli-responsive emulsions provide intense release of encapsulated substances upon the change in the environmental parameters. This can be used not only in medicine and pharmacology, but also in sensors, food industry, paint and varnish industry, petroleum production, etc.
 The bibliography includes 340 references
Nuclear–follower foraging behaviour between Western Australian common octopus and brown-spotted wrasse
Authors: Somaweera Ruchira , Somaweera Rehan
Published: July 2021

A common feeding association among reef fishes involves nuclear and follower species, where the former disturbs the bottom, during which the latter opportunistically feeds on items exposed. Here, we report such interactions between Western Australian common octopuses (Octopus (cf) tetricus) and brown-spotted wrasse (Notolabrus parilus) observed on eight occasions while snorkeling at four temperate-water reefs along the coast of Perth in Western Australia. We compare the interactions observed to other octopus-fish nuclear–follower associations known. In general, these interactions usually benefit the follower species and could play a significant role on reef trophodynamics.
Negative effects of nitrogen override positive effects of phosphorus on grassland legumes worldwide
Authors: Tognetti Pedro M. , Prober Suzanne M. , Báez Selene , Chaneton Enrique J. , Firn Jennifer , Risch Anita C. , Schuetz Martin , Simonsen Anna K. , Yahdjian Laura , Borer Elizabeth T. , Seabloom Eric W. , Arnillas Carlos Alberto , Bakker Jonathan D. , Brown Cynthia S. , Cadotte Marc W. , Caldeira Maria C. , Daleo Pedro , Dwyer John M. , Fay Philip A. , Gherardi Laureano A. , Hagenah Nicole , Hautier Yann , Komatsu Kimberly J. , McCulley Rebecca L. , Price Jodi N. , Standish Rachel J. , Stevens Carly J. , Wragg Peter D. , Sankaran Mahesh
Published: July 2021

Significance

Predicting the effects of anthropogenic nutrient enrichment on plant communities is critical for managing implications for biodiversity and ecosystem services. Plant functional types that fix atmospheric nitrogen (e.g., legumes) may be at particular risk of nutrient-driven global decline, yet global-scale evidence is lacking. Using an experiment in 45 grasslands across six continents, we showed that legume cover, richness, and biomass declined substantially with nitrogen additions. Although legumes benefited from phosphorus, potassium, and other nutrients, these nutrients did not ameliorate nitrogen-induced legume decline. Given global trends in anthropogenic nutrient enrichment, our results indicate the potential for global decline in grassland legumes, with likely consequences for biodiversity, food webs, soil health, and genetic improvement of protein-rich plant species for food production.
A platform utilizing
Drosophila
ovulation for nonhormonal contraceptive screening
Authors: Jiang Kewa , Zhang Jiyang , Huang Yuping , Wang Yingzheng , Xiao Shuo , Hadden M. Kyle , Woodruff Teresa K. , Sun Jianjun
Published: July 2021

Significance

Due to undesirable side effects and other risk factors of current hormonal contraceptives, the world has increasing demand for novel nonsteroidal contraceptives. Unfortunately, the development of nonsteroidal contraceptives for women is completely stalled due to little investment from big pharmaceutical companies in this field and lack of effective screening platforms. In this manuscript, we describe a phenotypic screening platform utilizing a
Drosophila
ovulation assay to identify lead compounds that can efficiently inhibit follicle rupture, a final step of releasing mature oocytes during ovulation. In addition, we demonstrate that lead compounds identified from
Drosophila
ovulation could inhibit follicle rupture in mice and have great potential to become nonsteroidal contraceptives for women.
An effective and efficient model of the near-field hydrodynamic interactions for active suspensions of bacteria
Authors: Zhang Bokai , Leishangthem Premkumar , Ding Yang , Xu Xinliang
Published: July 2021

Significance

Active suspensions of microswimmers demonstrate novel emergent behaviors (self-organizations, active turbulence, etc.) on macroscopic length scales. For such systems with, minimally, thousands of microswimmers, direct numerical simulations of the hydrodynamic interactions are computationally infeasible, and reduced models are needed. We demonstrated that existing models are not satisfactory in describing the hydrodynamic interactions for microswimmers in close proximity with even qualitatively erroneous predictions, indicating a pressing need for an adequate model. We propose a model that is both physically effective and computationally efficient in describing such hydrodynamics. The main novelty of our model is the description of hydrodynamic interactions through a resistance tensor, as opposed to an effective steric interaction in existing models.
Thirty-five years later: Long-term effects of the Matlab maternal and child health/family planning program on older women’s well-being
Authors: Barham Tania , Champion Brachel , Foster Andrew D. , Hamadani Jena D. , Jochem Warren C. , Kagy Gisella , Kuhn Randall , Menken Jane , Razzaque Abdur , Root Elisabeth Dowling , Turner Patrick S.
Published: July 2021

Significance

Few studies have addressed links between family planning programs and long-term benefits for women’s health and economic outcomes, especially in societies where old-age support and women’s status are tied to childbearing and where smaller families may carry negative consequences for women. We analyzed the maternal and child health/family planning (MCH/FP) program, a highly effective intervention introduced in the rural Matlab subdistrict of Bangladesh in 1977 with a subsequent 12-y differential in service access. We found significant differences in lifetime contraceptive behavior and completed fertility among women born 1938−1973. We found few effects on later health or economic outcomes except for an association of MCH/FP with poorer overall health and poorer metabolic health among women born 1950−1961.
Spiny and soft-rayed fin domains in acanthomorph fish are established through a BMP-gremlin-shhsignaling network
Authors: Höch Rebekka , Schneider Ralf F. , Kickuth Alison , Meyer Axel , Woltering Joost M.
Published: July 2021

Significance

The “spiny fin,” comprising the anterior part of the dorsal and anal fins, is an evolutionary novelty that contributed to the success of the spiny-rayed fishes. This domain contains heavily ossified spines that serve as defense mechanism and differ from the posterior flexible soft rays. We show that the partitioning of the median fins into spines and soft rays is established through canonical developmental mechanisms responsible for the anterior–posterior patterning of appendages. Furthermore, the coloration of the anal fin in males appears to be genetically linked to soft-ray identity. Comparative analysis including nonacanthomorph fins indicates that the convergent evolution of fin spines across fishes likely involved the repeated exaptation of a deeply conserved developmental program from the anterior fin.
Hydrogel–mesh composite for wound closure
Authors: Gao Yang , Han Xiuyuan , Chen Jiaojiao , Pan Yudong , Yang Meng , Lu Linhe , Yang Jian , Suo Zhigang , Lu Tongqing
Published: July 2021

Significance

Many surgeries require surgical mesh to be attached firmly at target areas to strengthen tissues, support organs, or repair wounds. Common methods of attachment include sutures, staples, and spiral tacks, but they damage tissues and prolong surgeries. Adhesion has been considered a promising alternative method to attach surgical meshes to tissues, but existing approaches of adhesion are too weak for most applications. Here, we develop composites of hydrogels and surgical meshes that can adhere to tissues firmly and stably. We demonstrate the applications of the hydrogel–mesh composites to wound closure, especially on tissues under high pressure or great tension.
VLM catecholaminergic neurons control tumor growth by regulating CD8
+
T cells
Authors: Zhang Ze , Li Yehua , Lv Xueyuan , Zhao Linlin , Wang Xiaodong
Published: July 2021

Significance

We have discovered that the ventrolateral medulla (VLM) catecholaminergic (CA) neurons, a group of neurons that control mouse stress response, are activated in tumor-bearing mice, and the neuronal activity promotes tumor growth in multiple syngeneic and spontaneous mouse tumor models. The tumor-promoting effect of these VLM CA neurons is mediated by cytotoxic T cells. These findings establish an interaction between a tumor and a group of neurons in the mouse brain that influences tumorigenesis and tumor growth by modulating adaptive immunity.
Rapid diagnosis and tumor margin assessment during pancreatic cancer surgery with the MasSpec Pen technology
Authors: King Mary E. , Zhang Jialing , Lin John Q. , Garza Kyana Y. , DeHoog Rachel J. , Feider Clara L. , Bensussan Alena , Sans Marta , Krieger Anna , Badal Sunil , Keating Michael F. , Woody Spencer , Dhingra Sadhna , Yu Wendong , Pirko Christopher , Brahmbhatt Kirtan A. , Van Buren George , Fisher William E. , Suliburk James , Eberlin Livia S.
Published: July 2021

Significance

Surgical removal of pancreatic cancer remains the only option for a cure. To verify the extent of tumor removal, surgeons rely on pathologic evaluation of frozen sections of surgical margins. However, this process can be challenging, time consuming, and subjective. Here, we used the MasSpec Pen to rapidly distinguish pancreatic cancer from healthy pancreatic and bile duct tissues by generating classification models based on the molecular signatures acquired from tissue. We evaluated this technology in an operating room during pancreatic surgeries and used these classification models to predict on data obtained in vivo and ex vivo with high performance. Our results suggest that the MasSpec Pen platform has the potential to improve and expedite margin evaluation during pancreatic cancer surgery.
Biotransformation modulates the penetration of metallic nanomaterials across an artificial blood–brain barrier model
Authors: Guo Zhiling , Zhang Peng , Chakraborty Swaroop , Chetwynd Andrew J , Abdolahpur Monikh Fazel , Stark Christopher , Ali-Boucetta Hanene , Wilson Sandra , Lynch Iseult , Valsami-Jones Eugenia
Published: July 2021

Significance

Although the brain is protected by a tight physiological guardian named the blood–brain barrier (BBB), deposition of engineered nanomaterials (ENMs) in the brain and consequent neurotoxicity has been reported. To date, it is still unclear whether and how ENMs enter the brain by crossing the BBB. In this study, we found that metallic ENMs transform in the BBB as affected by their shape, size, and intrinsic solubility, which in turn modulates their transport form, efficiency, and pathways through the BBB and, consequently, their neurotoxicity. The library of quantitative data on the chemical transformations presented here will support in silico modeling and prediction of the neurotoxicity of NMs and facilitate the tailored design of safe NMs.
Let-7b-5p in vesicles secreted by human airway cells reduces biofilm formation and increases antibiotic sensitivity of
P. aeruginosa
Authors: Koeppen Katja , Nymon Amanda , Barnaby Roxanna , Bashor Laura , Li Zhongyou , Hampton Thomas H. , Liefeld Amanda E. , Kolling Fred W. , LaCroix Ian S. , Gerber Scott A. , Hogan Deborah A. , Kasetty Swetha , Nadell Carey D. , Stanton Bruce A.
Published: July 2021

Significance

Pseudomonas aeruginosa
is one of the leading causes of hospital-acquired infections worldwide primarily due to its ability to develop antibiotic-resistant biofilms. This report describes a mechanism whereby human airway epithelial cells (AECs) increase the ability of antibiotics to kill
P. aeruginosa
and reduce the formation of drug-resistant biofilms. We demonstrate that human AECs secrete extracellular vesicles containing the microRNA let-7b-5p, that the vesicles deliver let-7b-5p to
P. aeruginosa
, and that let-7b-5p decreases biofilm formation and increases the ability of beta-lactam antibiotics to reduce biofilm formation by down-regulating key antibiotic-resistance and biofilm genes. A combination of let-7b, which is in clinical trials as an anti-inflammatory agent, and beta-lactam antibiotics may help combat antibiotic-resistant
P. aeruginosa
infections.
Understanding Opioid Overdose Risk and Response Preparedness among People who use Cocaine and other Drugs: Mixed-Methods Findings from a Large, Multi-City Study
Authors: Hughto Jaclyn M. W. , Gordon Lily K. , Stopka Thomas J. , Case Patricia , Palacios Wilson R. , Tapper Abigail , Green Traci C.
Published: July 2021

Background: Fatal overdoses involving cocaine (powdered or crack) and fentanyl have increased nationally and in Massachusetts. It is unclear how overdose risk and preparedness to respond to an overdose differs by patterns of cocaine and opioid use. Methods: From 2017 to 2019, we conducted a nine-community mixed-methods study of Massachusetts residents who use drugs. Using survey data from 465 participants with past-month cocaine and/or opioid use, we examined global differences ( p < 0.05) in overdose risk and response preparedness by patterns of cocaine and opioid use. Qualitative interviews ( n = 172) contextualized survey findings. Results: The majority of the sample (66%) used cocaine and opioids in the past month; 18.9% used opioids alone; 9.2% used cocaine and had no opioid use history; and 6.2% used cocaine and had an opioid use history. Relative to those with a current/past history of opioid use, significantly fewer of those with no opioid use history were aware of fentanyl in the drug supply, carried naloxone, and had received naloxone training. Qualitative interviews documented how people who use cocaine and have no history of opioid use are largely unprepared to recognize and respond to an overdose. Conclusions: Public health efforts are needed to increase fentanyl awareness and overdose prevention preparedness among people primarily using cocaine.