bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel mechanocaloric materials for solid-state cooling applications
Authors: Cazorla Claudio
Published: December 2019

Current refrigeration technologies based on compression cycles of greenhouse gases are environmentally threatening and cannot be scaled down to on-chip dimensions. Solid-state cooling is an environmentally friendly and highly scalable technology that may solve most of the problems associated with current refrigerant methods. Solid-state cooling consists of applying external fields (magnetic, electric, and mechanical) on caloric materials, which react thermally as a result of induced phase transformations. From an energy efficiency point of view, mechanocaloric compounds, in which the phase transitions of interest are driven by mechanical stresses, probably represent the most encouraging type of caloric materials. Conventional mechanocaloric materials like shape-memory alloys already display good cooling performances; however, in most cases they also present critical mechanical fatigue and hysteresis problems that limit their applicability. Finding new mechanocaloric materials and mechanisms that are able to overcome those problems, while simultaneously rendering large temperature shifts, is necessary to further advance the field of solid-state cooling. In this article, we review novel families of mechanocaloric materials that in recent years have been shown to be especially promising in the aspects that conventional mechanocaloric materials are not, and that exhibit unconventional but significant caloric effects. We emphasize elastocaloric materials, in which the targeted cooling spans are obtained through uniaxial stresses, since from an applied perspective they appear to be the most accomplished ones. Two different types of mechanocaloric materials emerge as particularly hopeful from our analysis: (1) compounds that exhibit field-induced order-disorder phase transitions involving either ions or molecules (polymers, fast-ion conductors, and plastic crystals), and (2) multiferroics in which the structural parameters are strongly coupled with the polar and/or magnetic degrees of freedom (magnetic alloys and oxide perovskites).
Thermoelectric and galvanomagnetic properties of topologically non-trivial (Co-M)Si semimetals (M = Fe, Ni) at high temperatures
Authors: Antonov A. , Ivanov Yu. , Konstantinov P. , Kuznetsova V. , Novikov S. , Ovchinnikov A. , Pshenay-Severin D. , Burkov A.
Published: December 2019

We present experimental and theoretical results on electronic structure, galvanomagnetic, and thermoelectric properties (Hall coefficient, electrical resistivity, and Seebeck coefficient) of Co1−xMxSi (M=Fe, Ni; x=0–0.1) compounds at temperatures from 80 K to 800 K. CoSi is a long known promising thermoelectric semimetal. Recently, it was shown that CoSi and the CoSi-based alloys belong to the family of materials with a topologically nontrivial electronic structure. We discuss possible connection of the observed dependences of the transport properties on temperature and alloy composition with ab initio electronic structure of the compounds. The electronic structure was calculated using density functional theory, and transport properties were analyzed in constant relaxation time, as well as in more realistic energy-dependent relaxation time approximations.
Light-activated electroforming in ITO/ZnO/p-Si resistive switching devices
Authors: Blázquez O. , Frieiro J. L. , López-Vidrier J. , Guillaume C. , Portier X. , Labbé C. , Hernández S. , Garrido B.
Published: December 2019

We report on light-activated electroforming of ZnO/p-Si heterojunction memristors with transparent indium tin oxide as the top electrode. Light-generated electron-hole pairs in the p-type substrate are separated by the external electric field and electrons are injected into the active ZnO layer. The additional application of voltage pulses allows achieving different resistance states that end up in the realization of the low resistance state (LRS). This process requires much less voltage compared to dark conditions, thus avoiding undesired current overshoots and achieving a self-compliant device. The transport mechanisms governing each resistance state are studied and discussed. An evolution from an electrode-limited to a space charge-limited transport is observed along the electroforming process before reaching the LRS, which is ascribed to the progressive formation of conductive paths that consequently induce the growth of conductive nanofilaments through the ZnO layer.
Wettability of laser-textured copper surface after a water-bath process
Authors: Cheng Hui-Chung , Chang Tien-Li , Lin Chao-Sung , Chen Ping-Hei
Published: December 2019

Although the wettability of ultrafast laser-textured surfaces has been widely studied recently, most studies have only investigated the transition mechanism of surface wettability after laser irradiation with elapsed time. It is already known that the laser-textured copper surface experiences a wettability transition from hydrophilicity to hydrophobicity due to the occurrence of partial deoxidation from CuO to Cu2O. This study investigates the surface wettability change of ultrafast (of the order of picoseconds) laser-textured copper surfaces treated with water baths of 50 °C and 100 °C. The pulse duration of the laser is 7 ps, the wavelength of the laser is 532 nm, and the fluence range is controlled at 1.27–2.97 J/cm2. This simple treatment changes laser-textured surfaces from hydrophobic to hydrophilic ones. Detailed surface chemical analyses revealed that the formation of Cu(OH)2 on top of the copper surfaces was attributed to the change in wettability.
Thickness induced microstructure, electronic structure and optoelectronic properties of Cu2S films deposited by radio frequency magnetron sputtering
Authors: Patel Tvarit A. , Panda Emila
Published: December 2019

This study addresses the influence of film thickness on the microstructure, electronic structure, and optoelectronic properties of Cu2S films. To this end, thickening Cu2S films are deposited on the soda lime glass substrate by varying the deposition time (t) from 60 to 420 min at room temperature (303 K) using radio frequency magnetron sputtering, and a range of experimental techniques are then used to characterize these films. Though films deposited at t of 60–360 min are found to have a pure Cu2S phase, an additional Cu1.8S phase is detected for the film deposited at 420 min. The valence state of Cu is found to be +1 in all these films, though the binding energy positions of the core level 2p electrons are found to shift systematically and are correlated to the thickness-induced compositional changes in these films. Sulfur is found to exist in two valence states in all these films: S−2 bound with Cu2S and elemental or nonstoichiometric S−n, the overall S−n/S−2 ratio being found to reduce with increasing film thickness. This microstructural adjustment in the thickening film is found to alter the electronic structure and optoelectronic properties of these films, measured using a wide range of experimental techniques. In the end, the principle behind the microstructure alteration of this thickening film is proposed.
Fabrication and characterization of IrMn/PtMn/PtCr/PtMn antiferromagnets in terms of the role of each layer
Authors: Saito Masamichi , Koike Fumihito
Published: December 2019

Herein, we investigated the exchange couplings in ferromagnet/antiferromagnet film systems of structures CoFe/Pt50Cr50, CoFe/interface-Pt50Mn50/Pt50Cr50, CoFe/interface-Pt50Mn50/Pt50Cr50/backed-Pt50Mn50, and CoFe/Ir20Mn80/interface-Pt50Mn50/Pt50Cr50/backed-Pt50Mn50. These investigations revealed that the backed(b)-PtMn(2.5–3.5 nm), the interface(i)-PtMn(2 nm), and the IrMn(0.8 nm)/i-PtMn(1.2 nm) significantly increased the unidirectional anisotropy constant (Jk) up to 0.67 erg/cm2. The insertion of an ultra-thin IrMn(0.8–1.2 nm) layer at the CoFe interface improved the CoFe hysteresis, i.e. the ratio of exchange bias field (Hex) to coercivity (Hc) was increased. The effects associated with thin b-PtMn, i-PtMn, and IrMn/i-PtMn layers were presumably due to a mismatch between lattice constant and a/c ratio of the PtCr. In other words, the larger lattice constants and lattice deformation during L10 transformation of PtMn may promote a dynamic-stress-induced PtCr ordering-assisting effect, though the PtCr thickness was reduced to 13 nm. The real cause of the effect of ultra-thin IrMn layers has not been properly explained to date. The blocking temperature (Tb) for the CoFe/i-PtMn(2 nm)/PtCr(25 nm)/b-PtMn(3 nm) film was 500 °C. Although the additional insertion of IrMn(0.8 nm) reduced Tb to 410 °C, the Tb and the normalized Hex did not depend on the PtCr thickness, which varied from 13 to 25 nm. Remarkably, an insertion of IrMn(0.8 nm) had no influence on the normalized Hex at temperatures below 300 °C.
Entropy growth and information gain in operating organized systems
Authors: Crevecoeur Guibert U.
Published: December 2019

In the framework of thermodynamics of irreversible processes, patterns of macroscopic evolution of operating organized systems from various fields (engineering, biology, cosmology) are coupled to the increase in their entropy. An extension of Boltzmann’s equation is proposed to characterize the entropy evolution. It is shown that such a “top-down” approach allows us to merge empirical data in a single inclusive model. A method is proposed to quantitatively assess the minimum semantic information gained during the life of the systems. This allows us to compare systems with different types of organization and lifespans. An example of calculation is given for the universe. The method also offers a challenging view to “bottom-up” approaches in progress.
The effect of a finite number of monomers available for aggregation at nucleation and micellization in a fixed volume
Authors: Shchekin A. K. , Koga K. , Volkov N. A.
Published: December 2019

The expressions for the minimal work of aggregate formation as a function of the aggregation number and monomer concentration for a system with a limited number of monomers and a fixed volume have additional terms in comparison with a bulk metastable phase. The role of these terms has been analyzed in the case of droplet homogeneous nucleation and micellization in a nonionic surfactant solution. The appearance of the potential well and direct and reversal aggregation barriers in such systems and their dependence on the system parameters and monomer concentration have been considered and compared.
Terahertz intersubband absorption of GaN/AlGaN step quantum wells grown by MOVPE on Si(111) and Si(110) substrates
Authors: Jollivet A. , Tchernycheva M. , Trinité V. , Frayssinet E. , De Mierry P. , Cordier Y. , Julien F. H.
Published: December 2019

We demonstrate terahertz intersubband absorptions in nitride step quantum wells (SQWs) grown by metal organic vapor phase epitaxy simultaneously on two different substrate orientations [Si(111) and Si(110)]. The structure of the SQWs consists of a 3 nm thick Al0.1Ga0.9N barrier, a 3 nm thick GaN well, and an Al0.05Ga0.95N step barrier with various thicknesses. This structure design has been optimized to approach a flatband potential in the wells to allow for an intersubband absorption in the terahertz frequency range and to maximize the optical dipole moment. Structural characterizations prove the high quality of the samples. Intersubband absorptions at frequencies of 5.6 THz (λ ≈ 54 μm), 7 THz (43 μm), and 8.9 THz (34 μm) are observed at 77 K on both substrate orientations. The observed absorption frequencies are in excellent agreement with calculations accounting for the depolarization shift induced by the electron concentration in the wells.
High temperature properties improvement and microstructure regulation of Sm2Co17-based permanent magnet
Authors: Wang Chao , Yu Nengjun , Zhu Minggang , Fang Yikun , Wang Shuai , Li Wei
Published: December 2019

It is well known that the high temperature magnetic properties of traditional Sm2Co17-based magnets can be further improved through adjustment of chemical composition and technique process. The Hcj of Sm(CobalFe0.1Cu0.09Zr0.03)z (z=7.0-7.3) magnets fluctuate over a large range at the variation of Sm content, and Sm(CobalFe0.1Cu0.09Zr0.03)7.2 magnet shows excellent magnetic properties as (BH)max of 22.5 MGOe, Hcj of 28.3 kOe and Br of 9.65 kG at room temperature respectively. Meantime through optimization of solid solution conditions, the Sm(CobalFe0.1Cu0.09Zr0.03)7.2 magnets possess excellent magnetic properties as Br=7.22 kG, Hcj=7.6 kOe, (BH)max=11.6 MGOe at 500 °C. The β (temperature coefficient of coercivity from room temperature to 500°C) can be optimized to +0.1113%/°C from −0.134%/°C as quenching temperature increases from 420 °C to 830 °C, but Hcj deteriorates to 1.4 kOe from 28 kOe. Distribution of Cu content in cell boundaries for Sm(CobalFe0.1Cu0.09Zr0.03)7.2 quenched at 420 °C and 830 °C was analyzed using TEM-EDS, the result indicates that distribution of Cu is the main reason to give rise to the variation of Hcj and β.
Effect of capping layer material on thermal tolerance of magnetic tunnel junctions with MgO/CoFeB-based free layer/MgO/capping layers
Authors: Honjo H. , Nguyen T. V. A. , Yasuhira M. , Niwa M. , Ikeda S. , Sato H. , Endoh T.
Published: December 2019

We investigate the effect of the capping layer on the thermal tolerance of magnetic tunnel junctions (MTJs) with free layer of MgO/CoFeB/spacer layer/CoFeB/MgO/capping layers (CoFeB, Ru, or Ta). We observe the largest perpendicular magnetic anisotropy energy density for the free layer with CoFeB capping layer using Ta spacer after annealing at 400°C for 1 h. Energy-dispersive X-ray (EDX) line analysis along film normal direction reveals the absorption of oxygen in MgO by Ta in the stack with Ta capping layer and Ru diffusion into CoFeB free layer in the stack with Ru capping layer, which could cause the reduction of perpendicular magnetic anisotropy. We also evaluate annealing temperature dependence of magnetic properties for the MTJ stacks with different spacer layer. We again observe the largest perpendicular magnetic anisotropy energy density for the MTJ stack using the CoFeB capping layer. The present study reveals that CoFeB capping layer is effective for achieving improved robustness against annealing.
Synthesis and electromagnetic wave absorption properties of FeCoNi(Si0.6Al0.2B0.2) high-entropy nanocrystalline alloy powders
Authors: Li Yanhui , Shang Shurui , Zhang Wei
Published: December 2019

FeCoNi(Si0.6Al0.2B0.2) high entropy alloy powders with flaky shapes of 14.7–17.6 μm in mean particle size and 8.2–14.9 in aspect ratio have been prepared by melt-spun and subsequent ball-milling for 10–50 h. The powders possess a mixing structure of BCC nanocrystalline and amorphous phases with average grain sizes of 6–20 nm. The powders exhibit soft magnetic characteristic with saturation magnetization of 78.6–88.1 emu/g. The powders/paraffin (mass ratio = 3:2) composites have high permeability, matchable permittivity, and excellent electromagnetic wave absorption properties in X- and Ku-bands. The composites with thicknesses of 1.2−2.0 mm possess minimum reflection losses (RL) of -38.1 to -44.1 dB with effective absorption bandwidths (RL<10 dB) of 2.5−3.8 GHz.
Quantum criticality and entropy transfer in spin chains and planes—Pyridine oxide copper salts
Authors: Trinh Jennifer , Schaller Daniel , LaBarre Patrick G. , Schlenker Kevin , Miller Joel S. , Ramirez Arthur P.
Published: December 2019

We present magnetic field-dependent specific heat (C) data for [Cu(pyO)6](NO3)2 (pyO = pyridine oxide) (CPN), a molecular salt shown to be quasi-1D, and for a quasi-2D analogue, [Cu(pyO)6](BF4)2 (CPB). For CPN, a sharp feature indicating 3D ordering is observed at 0.16K in zero-field. As the field, H, is increased, the ordering temperature first increases, as expected for quasi-1D antiferromagnets, before decreasing rapidly for H above 3T. The field also transfers the entropy of short-range ordering (SRO) in the spin chains into the 3D ordering peak. At our lowest accessible temperature, T ∼ 0.096K, C/T exhibits an enhanced peak at the critical field. Qualitatively similar behavior is found in CPB. These results demonstrate a potentially powerful new materials route to study quantum phase transitions.
Synthesis of Nd-Fe-B/Fe hybrid micro-magnets
Authors: Akdogan N. G. , Akdogan O.
Published: December 2019

There is an overgrowing interest in the synthesis of high performance micro magnets due to their wide application areas in MEMS, microfluidics, and micro-robotics. In addition, they possess great potential to become a model system for the development of next-generation hard magnets. In this study, NdFeB/Fe hybrid micro-magnets have been synthesized by a photolithography technique. NdFeB micro and Fe nano powders in the form of nano-thin flakes have been synthesized by one step surfactant assisted planetary ball milling. The fabricated nano-thin flakes with different lateral sizes have been obtained by varying the milling time. Room temperature coercivities of up to 3.1 kOe for NdFeB has been achieved after milling for 8 h. Photoresist and powders of NdFeB and Fe have been mixed at various powder-to-resist ratios. SU-8 has been chosen as the photoresist due to its resistance to chemicals and its suitability to be utilized in MEMS technology. Micro islands of SU-8/NdFeB/Fe have been prepared according to the manufacturer’s recommendations for pure SU-8. The hybrid micromagnets in pillar form have been successfully produced. The evolution of magnetic, structural and microstructural properties of these micro magnets will be reported. Successful fabrication of hybrid micro-magnets using the methodology prescribed in this work can pave the way for the development of next-generation MEMS.
Compensating inhomogeneous potential fields using two orthogonal spatially modulated laser beams
Authors: Gong Dongmei , Sun Zhendong , Wang Ying , Zhou Shuyu
Published: December 2019

The inhomogeneous potential residual field is the main impediment that prevents atomic samples from reaching sub-nanokelvin temperatures in deep cooling experiments. In this study, we propose a method to reduce the potential inhomogeneity using a pair of perpendicular spatially modulated laser beams. Two 2D distributions have been calculated by decomposing the required 3D compensation field and generated by employing Fourier optical systems. The proposed approach can be used to experimentally investigate Efimov physics in ultracold K-Rb mixtures.
Decoration of plasmonic Mg nanoparticles by partial galvanic replacement
Authors: Asselin Jérémie , Boukouvala Christina , Wu Yuchen , Hopper Elizabeth R. , Collins Sean M. , Biggins John S. , Ringe Emilie
Published: December 2019

Plasmonic structures have attracted much interest in science and engineering disciplines, exploring a myriad of potential applications owing to their strong light-matter interactions. Recently, the plasmonic concentration of energy in subwavelength volumes has been used to initiate chemical reactions, for instance by combining plasmonic materials with catalytic metals. In this work, we demonstrate that plasmonic nanoparticles of earth-abundant Mg can undergo galvanic replacement in a nonaqueous solvent to produce decorated structures. This method yields bimetallic architectures where partially oxidized 200–300 nm Mg nanoplates and nanorods support many smaller Au, Ag, Pd, or Fe nanoparticles, with potential for a stepwise process introducing multiple decoration compositions on a single Mg particle. We investigated this mechanism by electron-beam imaging and local composition mapping with energy-dispersive X-ray spectroscopy as well as, at the ensemble level, by inductively coupled plasma mass spectrometry. High-resolution scanning transmission electron microscopy further supported the bimetallic nature of the particles and provided details of the interface geometry, which includes a Mg oxide separation layer between Mg and the other metal. Depending on the composition of the metallic decorations, strong plasmonic optical signals characteristic of plasmon resonances were observed in the bulk with ultraviolet-visible spectrometry and at the single particle level with darkfield scattering. These novel bimetallic and multimetallic designs open up an exciting array of applications where one or multiple plasmonic structures could interact in the near-field of earth-abundant Mg and couple with catalytic nanoparticles for applications in sensing and plasmon-assisted catalysis.
Experimental dynamics of Newtonian non-elastic and viscoelastic droplets impacting immiscible liquid surface
Authors: Mohammad Karim Alireza
Published: December 2019

The dynamics of Newtonian nonelastic and viscoelastic droplets that impact an immiscible liquid surface were experimentally studied using high speed visualization techniques. The impact mechanisms of nonelastic droplets differed from those of viscoelastic droplets. The azimuthal instability seen along the rim bordering the nonelastic droplets was not observed during the impacting of viscoelastic droplets. The azimuthal instability is attributed to the Saffman–Taylor instability because of the viscosity discontinuity across the interface, and to the Rayleigh–Taylor and Richtmyer–Meshkov instabilities because of the density difference at the interface. The effects of the physical parameters, in terms of the Weber number, We, on the growth of the azimuthal instability were studied. The analysis revealed that the growth of the azimuthal instability increased the inertial force of the droplet upon impact. Moreover, surface tension-driven instability, known as the Plateau–Rayleigh instability, was also observed from impact of the nonelastic droplet, which was distinct from the viscoelastic droplets. The stabilizing role of the elasticity in the droplet impact was investigated using the elastocapillary number, Ec. For nonelastic droplets, the elastocapillary number is negligible, hence any disturbance could grow further and destabilize the liquid. However, for viscoelastic liquids, the Ec is significant due to the presence of elasticity, which prevents the growth of any disturbances in the liquid.
Quantum paraelectricity to dipolar glass transition in Sc doped BaFe12O19 single crystals
Authors: Yin L. H. , Zhang R. R. , Yang J. , Tong P. , Song W. H. , Dai J. M. , Zhu X. B. , Sun Y. P.
Published: December 2019

We report a quantum paraelectric (QP) to dipolar glass (DG) phase transition induced by Sc substitution in ferrimagnetic hexaferrite BaFe12−xScxO19 (0≤x≤2.4) single crystals. The DG behavior is revealed via anisotropic dielectric spectroscopy, polarization, and specific heat measurements. The phase evolution from QP to DG (0.5≤x≤1.2) and finally to the nonpolar state (x≥ 2.4) with increasing x is found to be due to the competition between the enhanced polar instability by lattice volume expansion and disordered/frustrated dipole-dipole interaction induced by the partial replacement of Sc3+ for Fe3+ in the bipyramids. Our results suggest further experimental clues to realize possible multiferroicity with strong displacive ferroelectricity in BaFe12O19 and other magnetic materials.
Thickness-dependent ultrafast nonlinear absorption properties of PtSe2 films with both semiconducting and semimetallic phases
Authors: Zhao Xin , Liu Fang , Liu Dongqi , Yan Xiao-Qing , Huo Changfu , Hui Wangwei , Xie Junfang , Ye Qing , Guo Chengcheng , Yao Yang , Liu Zhi-Bo , Tian Jian-Guo
Published: December 2019

The bandgap, electrical, and optical properties of PtSe2 depend dramatically on the vertical stacking and fabrication method. Here, we study the nonlinear absorption properties of the PtSe2 films composed of both semiconducting and semimetallic phases in a single film. These PtSe2 films exhibit remarkable thickness-dependent saturable absorption for femtosecond pulses at 400 nm and 800 nm. The saturation intensities decrease with the increase in the film thickness due to the accompanied increase in the semimetallic component and are much smaller than the reported values of PtSe2 synthesized by thermally assisted conversion. The saturable absorption characteristics are confirmed by time-resolved spectroscopies. The nonlinear refractive indexes of these PtSe2 films should be smaller than 1 × 10–12 cm2/W. Our results imply that the optical nonlinearities of PtSe2 could be flexibly tuned by the synthesis method and thickness.
Multivalent interaction of ESCO2 with the replication machinery is required for sister chromatid cohesion in vertebrates
Authors: Bender Dawn , Da Silva Eulália Maria Lima , Chen Jingrong , Poss Annelise , Gawey Lauren , Rulon Zane , Rankin Susannah
Published: December 2019

Significance

The cohesin complex both tethers together sister chromatids following DNA replication and ensures chromosome compaction and proper gene expression throughout interphase by folding chromosomes into loops and domains. How these very different activities of cohesin are controlled is largely unknown. The ESCO2 acetyltransferase modifies the SMC3 subunit of cohesin and is uniquely able to promote cohesion between sister chromatids, while the related ESCO1 acetyltransferase, which has the same catalytic activity, does not. Here we show that ESCO2 interacts with the DNA replication machinery through several highly conserved sequences in its unstructured tail. These interactions ensure that cohesin is modified precisely when sister chromatids are formed. This work provides a model to understand how cohesin activity is entrained to specific contexts.
Multielemental single–atom-thick
A
layers in nanolaminated V
2
(Sn,
A
) C (
A
= Fe, Co, Ni, Mn) for tailoring magnetic properties
Authors: Li Youbing , Lu Jun , Li Mian , Chang Keke , Zha Xianhu , Zhang Yiming , Chen Ke , Persson Per O. Å. , Hultman Lars , Eklund Per , Du Shiyu , Francisco Joseph S. , Chai Zhifang , Huang Zhengren , Huang Qing
Published: December 2019

Significance

M

n+1

AX

n

phases are a family of inherently nanolaminated ternary compounds with hexagonal crystal structure (space group
P

63

/mmc
,
194
). Here, M is vanadium element, and
A
is Fe, Co, Ni, Mn, or their binary/ternary/quaternary mixtures. Due to the elemental flexibility at A site, 15 nanolaminated V
2
(
A
x
Sn
1-x
)C MAX phases are synthesized, including 1 high-entropy MAX phase that all Fe, Co, Ni, Mn, and Sn elements simultaneously occupied A site. Tailoring of individual single–atom-thick layers in nanolaminated MAX phases offers atomic-level control of material properties, such as their distinct magnetic behaviors. The alloying in 2-dimensional A layer of MAX phases provides a unique route to design their crystal structure and to discover unexploited properties, which would develop promising functional materials for microelectronic device.
Does repeat synthesis in materials chemistry obey a power law?
Authors: Agrawal Mayank , Han Rebecca , Herath Dinushka , Sholl David S.
Published: December 2019

Significance

A key goal of much chemistry and materials research is the creation of new chemicals or materials. Understanding how readily the synthesis of a material can be repeated gives important insight into how a material can be adopted by a technical community or used in practical applications. Surprisingly, little is known about how often the synthesis of new materials gets repeated. In this paper, an extensive analysis of published literature for a specific class of materials, metal-organic frameworks, is used to quantitatively address this issue.
Analysis of the self-assembly process of Aspergillus oryzae hydrophobin RolA by Langmuir–Blodgett method
Authors: Terauchi Yuki , Tanaka Takumi , Mitsuishi Masaya , Yabu Hiroshi , Yoshimi Akira , Nantani Kei , Abe Keietsu
Published: December 2019

Hydrophobins are small, amphipathic proteins secreted by filamentous fungi. Hydrophobin RolA, which is produced by Aspergillus oryzae, attaches to solid surfaces, recruits the polyesterase CutL1, and consequently promotes hydrolysis of polyesters. Because this interaction requires the N-terminal, positively charged residue of RolA to be exposed on the solid surface, the orientation of RolA on the solid surface is important for recruitment. However, the process by which RolA forms the self-assembled structure at the interface remains unclear. Using the Langmuir–Blodgett technique, we analyzed the process by which RolA forms a self-assembled structure at the air–water interface and observed the structures on the hydrophobic or hydrophilic SiO2 substrates via atomic force microscopy. We found that RolA formed self-assembled films in two steps during phase transitions. We observed different assembled structures of RolA on hydrophilic and hydrophobic SiO2 substrates.
Activated human astrocyte‐derived extracellular vesicles modulate neuronal uptake, differentiation and firing
Authors: You Yang , Borgmann Kathleen , Edara Venkata Viswanadh , Stacy Satomi , Ghorpade Anuja , Ikezu Tsuneya
Published: December 2019

Astrocytes in the central nervous system (CNS) provide supportive neural functions and mediate inflammatory responses from microglia. Increasing evidence supports their critical roles in regulating brain homoeostasis in response to pro‐inflammatory factors such as cytokines and pathogen/damage‐associated molecular pattern molecules in infectious and neurodegenerative diseases. However, the underlying mechanisms of the trans‐cellular communication are still unclear. Extracellular vesicles (EVs) can transfer a large diversity of molecules such as lipids, nucleic acids and proteins for cellular communications. The purpose of this study is to characterize the EVs cargo proteins derived from human primary astrocytes (ADEVs) under both physiological and pathophysiological conditions. ADEVs were isolated from human primary astrocytes after vehicle (CTL) or interleukin‐1β (IL‐1β) pre‐treatment. Label‐free quantitative proteomic profiling revealed a notable up‐regulation of proteins including actin‐associated molecules, integrins and major histocompatibility complex in IL‐1β‐ADEVs compared to CTL‐ADEVs, which were involved in cellular metabolism and organization, cellular communication and inflammatory response. When fluorescently labelled ADEVs were added into primary cultured mouse cortical neurons, we found a significantly increased neuronal uptake of IL‐1β‐ADEVs compared to CTL‐ADEVs. We further confirmed it is likely due to the enrichment of surface proteins in IL‐1β‐ADEVs, as IL‐1β‐ADEVs uptake by neurons was partially suppressed by a specific integrin inhibitor. Additionally, treatment of neurons with IL‐1β‐ADEVs also reduced neurite outgrowth, branching and neuronal firing. These findings provide insight for the molecular mechanism of the ADEVs’ effects on neural uptake, neural differentiation and maturation, and its alteration in inflammatory conditions.
Eco-toxicity of water, soil, and sediment from agricultural areas of Kilombero Valley Ramsar wetlands, Tanzania
Authors: Materu S. F. , Heise S.
Published: December 2019

This study was conducted in the KVRS to; evaluate the seasonal eco-toxicity of water, soil and sediment samples; establish the suitability of using temperate biotest batteries in tropical systems; classify the toxicity of samples using Fuzzy Rules to estimate potential ecological risks. 143 water, sediment, and soil samples were collected during dry and rainy seasons in plantation areas.
Pseudokirchneriella subcapitata
,
Aliivibrio fischeri
and
Arthrobacter globiformis
bioassays were used to assess the toxicity of the samples. Results were categorized and classified into toxicity classes.

Dry season presented a significantly higher mean inhibition of 31% than 5% shown by rainy season samples (p < 0.001) in the bacterial bioassays, indicating a lower concentration of contaminants due to flooding and increased surface runoff. A few sediment samples resulted into 100% inhibition of
A. globiformis
, implying organisms were physiologically inactive upon exposure to contaminants. Seventy-three percent of samples posed little or no toxic potential risk, 25% posed critical risk and 1% posed elevated critical risk, implying the KVRS ecosystem might be at risk if the extensive usage of pesticides in the area is not well managed and monitored. The temperate micro-biotests can be used in tropical systems, but with further research on suitable organisms and standardized methods.
The rigidity and stability of complete 𝑓-minimal hypersurfaces in ℝⁿ×𝕊¹(𝕒)
Authors: Li Xingxiao , Li Juntao
Published: December 2019

In this paper we consider

f
f

-minimal hypersurfaces in the product space

R

n

×

S

1

(
a
)

\mathbb {R}^n \times \mathbb {S}^1(a)

where

(

R

n

,

e

−
f

d
μ
)

(\mathbb {R}^n,e^{-f}d\mu )

is the standard Gaussian space with

d
μ

d\mu

being the standard volume element on

R

n

\mathbb {R}^n

. By introducing a globally defined smooth function

α
\alpha

, we shall derive some interesting differential identities by which we are able to prove several rigidity theorems. We also study the stability properties of some standard examples. As a result, we prove that

R

n

×
{

s
0

}
↪

R

n

×

S

1

(
a
)

\mathbb {R}^n \times \{s_0\} \hookrightarrow \mathbb {R}^n \times \mathbb {S}^1(a)

is the only complete, proper, and stable

f
f

-minimal hypersurface.
Uniform rank gradient, cost, and local-global convergence
Authors: Abért Miklós , Tóth László
Published: December 2019

We analyze the rank gradient of finitely generated groups with respect to sequences of subgroups of finite index that do not necessarily form a chain, by connecting it to the cost of p.m.p. (probability measure preserving) actions. We generalize several results that were only known for chains before. The connection is made by the notion of local-global convergence.

In particular, we show that for a finitely generated group

Γ
\Gamma

with fixed price

c
c

, every Farber sequence has rank gradient

c
−
1

c-1

. By adapting Lackenby’s trichotomy theorem to this setting, we also show that in a finitely presented amenable group, every sequence of subgroups with index tending to infinity has vanishing rank gradient.
Dynamics of triadin, a muscle-specific triad protein, within sarcoplasmic reticulum subdomains
Authors: Sébastien Muriel , Aubin Perrine , Brocard Jacques , Brocard Julie , Marty Isabelle , Fauré Julien
Published: December 2019

In skeletal muscle, mechanisms allowing the localization of the calcium release complex (CRC) in reticulum–plasma membrane contact points (triads) are unknown. It is shown that the CRC protein T95 has a constant diffusion in reticulum membranes and acquires a long residence time in triad because of its transmembrane domain.
Discontinuous Hamiltonian Monte Carlo for discrete parameters and discontinuous likelihoods
Authors: Nishimura Akihiko , Dunson David B , Lu Jianfeng
Published: December 2019

Hamiltonian Monte Carlo has emerged as a standard tool for posterior computation. In this article we present an extension that can efficiently explore target distributions with discontinuous densities. Our extension in particular enables efficient sampling from ordinal parameters through the embedding of probability mass functions into continuous spaces. We motivate our approach through a theory of discontinuous Hamiltonian dynamics and develop a corresponding numerical solver. The proposed solver is the first of its kind, with a remarkable ability to exactly preserve the Hamiltonian. We apply our algorithm to challenging posterior inference problems to demonstrate its wide applicability and competitive performance.
Effect of multiple episodes of acute kidney injury on mortality: an observational study
Authors: Walker Heather , De Souza Nicosha , Hapca Simona , Witham Miles D , Bell Samira
Published: December 2019

Background

Patients who survive an episode of acute kidney injury (AKI) are more likely to have further episodes of AKI. AKI is associated with increased mortality, with a further increase with recurrent episodes. It is not clear whether this is due to AKI or as a result of other patient characteristics. The aim of this study was to establish whether recurrence of AKI is an independent risk factor for mortality or if excess mortality is explained by other factors.

Methods

This observational cohort study included adult people from the Tayside region of Scotland, with an episode of AKI between 1 January 2009 and 31 December 2009. AKI was defined using the creatinine-based Kidney Disease: Improving Global Outcomes definition. Associations between recurrent AKI and mortality were examined using a Cox proportional hazards model.

Results

Survival was worse in the group identified to have recurrent AKI compared with those with a single episode of AKI [hazard ratio = 1.49, 95% confidence interval (CI) 1.37–1.63; P < 0.001]. After adjustment for comorbidities, stage of reference AKI, sex, age, medicines that predispose to renal impairment or, in the 3 months prior to the reference AKI, deprivation and baseline estimated glomerular filtration rate (eGFR), recurrent AKI was independently associated with an increase in mortality (hazard ratio = 1.25, 95% CI 1.14–1.37; P < 0.001). Increasing stage of reference AKI, age, deprivation, baseline eGFR, male sex, previous myocardial infarction, cerebrovascular disease and diuretic use were all associated with an increased risk of mortality in patients with recurrent AKI.

Conclusions

Recurrent AKI is associated with increased mortality. After adjusting for patient characteristics, the increase in mortality is independently associated with recurrent AKI and is not solely explained by other risk factors.
Differential distribution of N- and O-Glycans and variable expression of sialyl-T antigen on HeLa cells—Revealed by direct fluorescent glycan imaging
Authors: Wu Zhengliang L , Person Anthony D , Zou Yonglong , Burton Andrew J , Singh Ravinder , Burroughs Barbara , Fryxell Dan , Tatge Timothy J , Manning Timothy , Wu Guoping , Swift Karl A D , Kalabokis Vassili
Published: December 2019

Cells are covered with glycans. The expression and distribution of specific glycans on the surface of a cell are important for various cellular functions. Imaging these glycans is essential to aid elucidation of their biological roles. Here, utilizing methods of direct fluorescent glycan imaging, in which fluorescent sialic acids are directly incorporated into substrate glycans via recombinant sialyltranferases, we report the differential distribution of N- and O-glycans and variable expression of sialyl-T antigen on HeLa cells. While the expression of N-glycans tends to be more peripheral at positions where cell–cell interaction occurs, O-glycan expression is more granular but relatively evenly distributed on positive cells. While N-glycans are expressed on all cells, sialyl-T antigen expression exhibits a wide spectrum of variation with some cells being strongly positive and some cells being almost completely negative. The differential distribution of N- and O-glycans on cell surface reflects their distinctive roles in cell biology.
Evaluation of Surgical Caseload Aboard the USNS COMFORT (T-AH 20) During Enduring Promise 2018
Authors: Norris Emily A , Johnson Mark S , Mann Kevan E , Pryor Howard I
Published: December 2019

The USNS COMFORT (T-AH-20) deployed in support of Enduring Promise 2018 (EP-18) for an 11-week humanitarian mission providing care to the residents of four host nations in Central and South America. The COMFORT provides the capability of providing medical, dental, and surgical care in humanitarian aid missions.
Genioglossus motor unit activity in supine and upright postures in obstructive sleep apnea
Authors: Luu Billy L , Saboisky Julian P , McBain Rachel A , Trinder John A , White David P , Taylor Janet L , Gandevia Simon C , Butler Jane E
Published: December 2019

This study investigated whether a change in posture affected the activity of the upper-airway dilator muscle genioglossus in participants with and without obstructive sleep apnea (OSA). During wakefulness, a monopolar needle electrode was used to record single motor unit activity in genioglossus in supine and upright positions to alter the gravitational load that causes narrowing of the upper airway. Activity from 472 motor units was recorded during quiet breathing in 17 males, nine of whom had OSA. The mean number of motor units for each participant was 11.8 (SD 3.4) in the upright and 16.0 (SD 4.2) in the supine posture. For respiratory-modulated motor units, there were no significant differences in discharge frequencies between healthy controls and participants with OSA. Within each breath, genioglossus activity increased through the recruitment of phasic motor units and an increase in firing rate, with an overall increase of ~6 Hz (50%) across both postures and participant groups. However, the supine posture did not lead to compensatory increases in the peak discharge frequencies of inspiratory and expiratory motor units, despite the increase in gravitational load on the upper airway. Posture also had no significant effect on the discharge frequency of motor units that showed no respiratory modulation during quiet breathing. We postulate that, in wakefulness, any increase in genioglossus activity to compensate for the gravitational effects on the upper airway is achieved primarily through the recruitment of additional motor units in both healthy controls and participants with OSA.
Morphological and Molecular Identification of Seedborne Fungi in Squash (Cucurbita maxima, Cucurbita moschata)
Authors: Moumni Marwa , Allagui Mohamed Bechir , Mancini Valeria , Murolo Sergio , Tarchoun Neji , Romanazzi Gianfranco
Published: December 2019

Squash is one of the most important crops of tropical and temperate regions, and it can be affected by several fungal pathogens. Most of these pathogens infect the seeds, which become an efficient vehicle to disperse seedborne pathogens over long distances, with consequent severe crop losses. The main objective of this study was the identification of the principal seedborne fungi in seeds extracted from 66 samples of asymptomatic and symptomatic squash fruit (Cucurbita maxima, Cucurbita moschata) collected in two countries, Tunisia and Italy. The symptoms of fruit decay were identified and classified according to lesion size. Following the blotter test, 14 fungal species were detected from the seeds. Seedborne fungi were identified in all fruit samples tested, including asymptomatic fruit. The most frequent fungi from Tunisian seeds were Alternaria alternata (25.1%), followed by Stagonosporopsis cucurbitacearum (24.6%), Fusarium solani (16.6%), Rhizopus stolonifer (13.3%), F. fujikuroi (7.8%), Albifimbria verrucaria (3.3%), and Stemphylium vesicarium (2.3%). For the fruits from Italy, the most frequently identified fungal species in seed samples were Alternaria alternata (40.0%), followed by F. fujikuroi (20.8%), Stemphylium vesicarium (3.0%), and Curvularia spicifera (2.1%). Morphological identification was confirmed by molecular diagnosis using the available species-specific primers. Furthermore, specific primers were designed to identify Albifimbria verrucaria, Paramyrothecium roridum, and Stemphylium vesicarium. Application of seed-health testing methods, including such conventional and molecular diagnostic tools, will help to improve seed quality and crop yields.
Genetic Diversity ofColletotrichumspp. Causing Strawberry Anthracnose in Zhejiang, China
Authors: Chen X. Y. , Dai D. J. , Zhao S. F. , Shen Y. , Wang H. D. , Zhang C. Q.
Published: December 2019

Anthracnose is a serious fungal disease that primarily infects strawberry roots and stolons during development. Here, 91 isolates from different areas of Zhejiang province, China, were collected. Morphological characteristics were analyzed, and a phylogenetic analysis based on multiple genes (actin, internal transcribed spacer, calmodulin, glyceraldehyde-3-phosphate dehydrogenase, and chitin synthase) was performed. We found that all of the Colletotrichum species causing strawberry anthracnose belonged to the Colletotrichum gloeosporioides complex. Among them, we identified 48 isolates of C. fructicola, 21 isolates of C. siamense, 13 isolates of C. gloeosporioides, and 9 isolates of C. aenigma. C. siamense was distributed in the central and eastern regions of Zhejiang province (Hangzhou, Jinhua, Shaoxing, Ningbo, and Taizhou). This is the first report of C. siamense causing strawberry anthracnose in Zhejiang province. C. fructicola was the most dominant species causing strawberry anthracnose in Zhejiang province. We identified the four species causing strawberry anthracnose in Zhejiang province, which will improve our understanding of the strawberry anthracnose epidemic and will benefit the development of future control measures.
Peanut Yield Loss in the Presence of Defoliation Caused by Late or Early Leaf Spot
Authors: Anco Daniel J. , Thomas James S. , Jordan David L. , Shew Barbara B. , Monfort W. Scott , Mehl Hillary L. , Small Ian M. , Wright David L. , Tillman Barry L. , Dufault Nicholas S. , Hagan Austin K. , Campbell H. Lee
Published: December 2019

Late and early leaf spot, respectively caused by Nothopassalora personata and Passalora arachidicola, are damaging diseases of peanut (Arachis hypogaea) capable of defoliating canopies and reducing yield. Although one of these diseases may be more predominant in a given area, both are important on a global scale. To assist informed management decisions and quantify relationships between end-of-season defoliation and yield loss, meta-analyses were conducted over 140 datasets meeting established criteria. Slopes of proportion yield loss with increasing defoliation were estimated separately for Virginia and runner market type cultivars. Yield loss for Virginia types was described by an exponential function over the range of defoliation levels, with a loss increase of 1.2 to 2.2% relative to current loss levels per additional percent defoliation. Results for runner market type cultivars showed yield loss to linearly increase 2.2 to 2.8% per 10% increase in defoliation for levels up to approximately 95% defoliation, after which the rate of yield loss was exponential. Defoliation thresholds to prevent economic yield loss for Virginia and runner types were estimated at 40 and 50%, respectively. Although numerous factors remain important in mitigating overall yield losses, the integration of these findings should aid recommendations about digging under varying defoliation intensities and peanut maturities to assist in minimizing yield losses.