bluuebunny/crossref_metadata_2025 huggingface dataset:
Mapping of azimuthal B-fields in Z-pinch plasmas using Z-pinch-driven ion deflectometry
Authors: Munzar V. , Klir D. , Cikhardt J. , Kravarik J. , Kubes P. , Malir J. , Novotny J. , Rezac K. , Shishlov A. V. , Kokshenev V. A. , Cherdizov R. K. , Ratakhin N. A.
Published: June 2021

B-field measurements are crucial for the study of high-temperature and high-energy-density plasmas. A successful diagnostic method, ion deflectometry (radiography), is commonly employed to measure MGauss magnetic fields in laser-produced plasmas. It is based on the detection of multi-MeV ions, which are deflected in B-fields and measure their path integral. Until now, protons accelerated via laser–target interactions from a point-like source have been utilized for the study of Z-pinch plasmas. In this paper, we present the results of the first Z-pinch-driven ion deflectometry experiments using MeV deuterium beams accelerated within a hybrid gas-puff Z-pinch plasma on the GIT-12 pulse power generator. In our experimental setup, an inserted fiducial deflectometry grid (D-grid) separates the imploding plasma into two regions of the deuteron source and the studied azimuthal B-fields. The D-grid is backlighted by accelerated ions, and its shadow imprinted into the deuteron beams demonstrates ion deflections. In contrast to the employment of the conventional point-like ion source, in our configuration, the ions are emitted from the extensive and divergent source inside the Z-pinch. Instead of having the point ion source, deflected ions are selected via a point projection by a pinhole camera before their detection. Radial distribution of path-integrated B-fields near the axis (within a 15 mm radius) is obtained by analysis of experimental images (deflectograms). Moreover, we present a 2D topological map of local azimuthal B-fields B(r,z) via numerical retrieval of the experimental deflectogram.
Asymmetric phononic frequency comb in a rhombic micromechanical resonator
Authors: Yang Qiqi , Wang Xuefeng , Huan Ronghua , Xu Liu , Xu Yutao , Jiang Zhuangde , Wei Xueyong
Published: June 2021

As an analog of the optical frequency comb, the phononic frequency comb has been demonstrated in mechanical resonators recently. In this Letter, we generate the frequency comb in a rhombic micro-resonator with stiffness parametrically modulated by low-frequency pumping. Interestingly, this comb exhibits the asymmetry in the amplitude, i.e., the amplitudes of comb fingers on either side of the central comb finger decay with different rates. With a parametrically modulated model, we analyzed in detail the asymmetry in the frequency comb and accurately captured the reason for the asymmetry. Furthermore, the asymmetry of the frequency comb can be adjusted experimentally. These results provide a theoretical basis for manipulating the comb fingers and are expected to open the door for potential applications of the frequency comb.
Apparatus for generation of nanojoule-class water-window high-order harmonics
Authors: Nishimura Kotaro , Fu Yuxi , Suda Akira , Midorikawa Katsumi , Takahashi Eiji J.
Published: June 2021

In our recent study [Fu et al., Commun. Phys. 3(1), 92 (2020)], we have developed an approach for energy-scaling of high-order harmonic generation in the water-window region under a neutral-medium condition. More specifically, we obtained a nanojoule-class water-window soft x-ray harmonic beam under a phase-matching condition. It has been achieved by combining a newly developed terawatt-class mid-infrared femtosecond laser and a loose-focusing geometry for high-order harmonic generation. The generated beam is more than 100 times intense compared to previously reported results. The experimental setup included two key parts: a terawatt mid-infrared femtosecond driving laser [Fu et al., Sci. Rep. 8(1), 7692 (2018)] and a specially designed gas cell. Despite the dramatic drop in the optimal gas pressure for phase-matching due to loose-focusing geometry, it still reached the 1 bar level for helium. Thus, we have designed a double-structured pulsed-gas cell with a differential pumping system, which enabled providing sufficiently high gas pressure. Moreover, it allowed reducing gas consumption significantly. A robust energy-scalable apparatus for high-order harmonic generation developed in this study will enable the generation of over ten-nanojoule water-window attosecond pulses in the near future.
Single photon emission from ODT passivated near-surface GaAs quantum dots
Authors: Cao Xin , Yang Jingzhong , Li Pengji , Zhang Yiteng , Rugeramigabo Eddy P. , Brechtken Benedikt , Haug Rolf J. , Zopf Michael , Ding Fei
Published: June 2021

Epitaxially grown semiconductor quantum dots are promising candidates for pure single photon and polarization-entangled photon pair emission. Excellent optical properties can typically be ensured only if these so-called “artificial atoms” are buried deep inside the semiconductor host material. Quantum dots grown close to the surface are prone to charge carrier fluctuations and trap states on the surface, degrading the brightness, coherence, and stability of the emission. We report on high-purity single photon emission [g(2)(0) = 0.016 ± 0.015] of GaAs/AlGaAs quantum dots that were grown only 20 nm below the surface. Chemical surface passivation with sulfur compounds such as octadecanethiol has been performed on quantum dots with 20, 40, and 98 nm from the surface. The reduction of the density and influence of surface states causes improvements in linewidth and photoluminescence intensity as well as a well-preserved single photon emission. Therefore, the realization of hybrid nanophotonic devices, comprising near-field coupling and high-quality optical properties, comes into reach.
Modulation characteristics of uncooled graphene photodetectors
Authors: Ryzhii V. , Ryzhii M. , Otsuji T. , Leiman V. , Mitin V. , Shur M. S.
Published: June 2021

We report on the modulation characteristics of the uncooled terahertz (THz) and infrared (IR) detectors using uniform graphene layers (GLs) and perforated graphene layers (PGL). Our analysis shows that the PGL detectors could have more than an order of magnitude smaller dark current compared to more conventional GL reversed biased photodetectors operating in the same frequency range. The modulation mechanism for the simulated photodetectors is the variation of the density and effective temperature of the two-dimensional electron–hole plasma with the varying intensity of the THz or IR radiation. Our simulations predict a reasonable modulation depth up to the modulation frequencies of 50 GHz for the impinging radiation frequencies up to the mid-IR range.
Ultrafast x-ray pump x-ray probe transient absorption spectroscopy: A computational study and proposed experiment probing core-valence electronic correlations in solvated complexes
Authors: Liekhus-Schmaltz Chelsea E. , Ho Phay J. , Weakly Robert B. , Aquila Andrew , Schoenlein Robert W. , Khalil Munira , Govind Niranjan
Published: June 2021

Femtosecond x-ray pump–x-ray probe experiments are currently possible at free electron lasers such as the linac coherent light source, which opens new opportunities for studying solvated transition metal complexes. In order to make the most effective use of these kinds of experiments, it is necessary to determine which chemical properties an x-ray probe pulse will measure. We have combined electron cascade calculations and excited-state time-dependent density functional theory calculations to predict the initial state prepared by an x-ray pump and the subsequent x-ray probe spectra at the Fe K-edge in the solvated model transition metal complex, K4FeII(CN)6. We find several key spectral features that report on the ligand-field splitting and the 3p and 3d electron interactions. We then show how these features could be measured in an experiment.
Enhanced carrier injection hotspot effect by direct and simple ITO surface engineering
Authors: Jiang Hui-Hui , Xiao Jing , Huang Hai-Tian , Wu Di , Song Ru-Xin , Xu Rong , Gao Xu , Xu Jian-Long , Duhm Steffen , Chi Li-Feng , Wang Sui-Dong
Published: June 2021

Direct and simple surface engineering of indium tin oxide (ITO) by appropriate Ar plasma treatment was used to induce the carrier injection hotspot effect, similar to reported indirect approaches based on the introduction of additional nanostructures on ITO. Surface characterization analyses and electric field simulations indicate the formation of small-sized and dense injection hotspots on the treated ITO. Efficient electron injection was achieved in both inverted organic light-emitting diodes and corresponding electron-only devices employing the treated ITO as bottom cathode. The present results show that, in addition to the electronic structure, the microscopic morphology at the contacts could also play a critical role in achieving efficient carrier injection in organic electronic/optoelectronic devices.
Multimodal real-time frequency tracking of cantilever arrays in liquid environment for biodetection: Comprehensive setup and performance analysis
Authors: De Pastina Annalisa , Padovani Francesco , Brunetti Giulio , Rotella Chiara , Niosi Fabio , Usov Victor , Hegner Martin
Published: June 2021

We present a nanomechanical platform for real-time quantitative label-free detection of target biomolecules in a liquid environment with mass sensitivity down to few pg. Newly fabricated arrays of up to 18 cantilevers are integrated in a micromachined fluidic chamber, connected to software-controlled fluidic pumps for automated sample injections. We discuss two functionalization approaches to independently sensitize the interface of different cantilevers. A custom piezo-stack actuator and optical readout system enable the measurement of resonance frequencies up to 2 MHz. We implement a new measurement strategy based on a phase-locked loop (PLL), built via in-house developed software. The PLL allows us to track, within the same experiment, the evolution of resonance frequency over time of up to four modes for all the cantilevers in the array. With respect to the previous measurement technique, based on standard frequency sweep, the PLL enhances the estimated detection limit of the device by a factor of 7 (down to 2 pg in 5 min integration time) and the time resolution by more than threefold (below 15 s), being on par with commercial gold-standard techniques. The detection limit and noise of the new setup are investigated via Allan deviation and standard deviation analysis, considering different resonance modes and interface chemistries. As a proof-of-concept, we show the immobilization and label-free in situ detection of live bacterial cells (E. coli), demonstrating qualitative and quantitative agreement in the mechanical response of three different resonance modes.
Ultraviolet-induced oxygen vacancy in SrTiO3 polycrystalline
Authors: Sriondee Manlika , Chirayutthanasak Ooraphan , Nammahachak Nant , Eknapakul Tanachat , Nakajima Hideki , Meevasana Worawat , Ratanaphan Sutatch
Published: June 2021

The influence of ultraviolet (UV)-induced oxygen vacancies on dynamic changes of electrical conductance in a random-oriented SrTiO3 polycrystalline and SrTiO3 single crystals with (100), (110), and (111) surfaces is reported in this study. It was discovered that a large fraction of ultraviolet-induced oxygen vacancies in the SrTiO3 polycrystalline are primarily contributed from grain boundaries, but these oxygen vacancies are less influenced to the reversible conductance changes due to UV irradiation. The dynamic change of electrical conductance in the polycrystalline is similar to what has been observed for the polar (110) and (111) oriented single crystals, offering a potential alternative for multifunctional electronic devices.
Ultrathin and high-efficiency Pancharatnam–Berry phase metalens for millimeter waves
Authors: Moreno-Peñarrubia Alexia , Teniente Jorge , Kuznetsov Sergei , Orazbayev Bakhtiyar , Beruete Miguel
Published: June 2021

Applying the Pancharatnam–Berry (PB) principle to half-wave plate (HWP) metasurfaces allows the manipulation of wavefronts along with the conversion of the handedness of circularly polarized incident waves by simply rotating the meta-atoms that compose the metasurface. PB metasurfaces (PBM) working in transmission mode with four or more layers have been demonstrated to reach levels of transmission efficiency near 100% but also have resulted in bulky structures. On the other hand, compact tri-layer ultrathin (λ/8) designs have reached levels near 90% but are more challenging than single- or bi-layer structures from a manufacturing viewpoint. Here, we propose a compact ultrathin (<λ/13) transmissive PBM with only two layers (which significantly simplifies the fabrication process) achieving a transmission efficiency level of around 90%, focusing the wavefront of a circularly polarized incident wave and converting its handedness. The metasurface is composed of identical bi-layered H-shaped unit cells (meta-atoms) whose transmission phases are chosen by introducing different rotation angles to each unit cell according to a lens spatial phase profile. The structure is analytically and numerically studied and experimentally measured, verifying an excellent behavior as an HWP PB metalens at 87 GHz.
High-mobility n−-GaN drift layer grown on Si substrates
Authors: Shen Jianfei , Yang Xuelin , Huang Huayang , Liu Danshuo , Cai Zidong , Chen Zhenghao , Ma Cheng , Xu Fujun , Sang Liwen , Wang Xinqiang , Ge Weikun , Shen Bo
Published: June 2021

We have investigated the interaction between carbon impurities and threading dislocations and their impact on the transport properties of GaN grown on Si substrates. The incorporation of carbon impurity was found to be associated with dislocation density, with a linear dependence. It indicates that the carbon may accumulate around the dislocations. The temperature-dependent Hall-effect measurement further confirmed that those carbon-decorated dislocations can act as acceptor-like traps, existing at every c-lattice spacing along a threading dislocation. The acceptor-like traps are important scattering centers and, thus, cannot be neglected. By reducing the density of the carbon-decorated dislocation via introducing a thick dislocation filtering layer to reduce the dislocation-related acceptor-like trap scattering, a record room-temperature electron mobility of 1090 cm2/V s with a carrier concentration of ∼2 × 1016 cm−3 for n--GaN on Si was achieved. Our results provide an effective approach to obtain high-quality n−-GaN on Si for vertical GaN based devices.
The impact of interfacial Si contamination on GaN-on-GaN regrowth for high power vertical devices
Authors: Fu Kai , Fu Houqiang , Deng Xuguang , Su Po-Yi , Liu Hanxiao , Hatch Kevin , Cheng Chi-Yin , Messina Daniel , Meidanshahi Reza Vatan , Peri Prudhvi , Yang Chen , Yang Tsung-Han , Montes Jossue , Zhou Jingan , Qi Xin , Goodnick Stephen M. , Ponce Fernando A. , Smith David J. , Nemanich Robert , Zhao Yuji
Published: June 2021

The development of gallium nitride (GaN) power devices requires a reliable selective-area doping process, which is difficult to achieve because of ongoing challenges associated with the required etch-then-regrow process. The presence of silicon (Si) impurities of unclear physical origin at the GaN regrowth interface has proven to be a major bottleneck. This paper investigates the origin of Si contamination at the epitaxial GaN-on-GaN interface and demonstrates an approach that markedly reduces its impact on device performance. An optimized dry-etching approach combined with UV-ozone and chemical etching is shown to greatly reduce the Si concentration levels at the regrowth interface, and a significant improvement in a reverse leakage current in vertical GaN-based p–n diodes is achieved.
The large photoresponse and high polarization sensitivity of Te-based optoelectronic devices with the adsorbed hydroxide ions
Authors: Gong Le-Le , Xiong Wen , Xie Yi-Qun , Hu Jie , Huang Pu , Wang Fei
Published: June 2021

The large photogalvanic effect photocurrent is desirable in noncentrosymmetric materials, which may promote practical applications in optoelectronic devices. Here, based on the quantum transport simulations, we propose that the maximum photocurrent of recent attractive Te-based optoelectronic devices can be increased close to 20 times by adsorbing hydroxide ions at the two most stable sites (Te-C and Te-T sites) under the irradiation of the linearly polarized light. Moreover, we also analyze the photon energy of electron transition corresponding to the maximum photocurrent by the transmission spectrum of the devices. Additionally, the calculated extinction ratio of the adsorbed devices representing the polarization sensitivity can be reached to the maximum of about 169.7. Therefore, our results provide a feasible method for improving the photoresponse with the high polarization sensitivity of Te-base devices.
Enhancing the optical rotation of chiral molecules using helicity preserving all-dielectric metasurfaces
Authors: Beutel D. , Scott P. , Wegener M. , Rockstuhl C. , Fernandez-Corbaton I.
Published: June 2021

Being able to sense and distinguish the handedness of chiral molecules is crucial for many applications in the life sciences. Here, we explore by theoretical and computational means the ability of achiral and helicity preserving photonic nanostructures to enhance the optical rotation, i.e., the polarization rotation of elliptically polarized light while traversing a solution of chiral molecules. Starting from a helicity preserving isolated dielectric cylinder, we assemble an array thereof, which enhances the optical rotation power by a factor of four, being limited by the inability to enhance the helicity density beyond the near fields attached to the array. To overcome this limitation, we study cavities composed of two arrays of cylinders with the solution of molecules in between. Such cavities enhance the optical rotation power by a factor as large as 270. Our work complements previous research that concentrated on enhancing circular dichroism with similar structures. Measuring and enhancing circular dichroism as well as optical rotation provides more complete information about the molecules under investigation.
Thermodynamic analysis and prediction on the wetting properties of pore array superhydrophobic laser-texturing surfaces
Authors: Hong Xiaozhe , Hu Huixiang , Gao Yan
Published: June 2021

Superhydrophobic surfaces fabricated by laser irradiation on various materials have been reported recently to show excellent wetting properties. However, there are only limited works regarding the theoretical analysis and prediction of the wetting properties of different surface structures, especially the widely used pore array laser-texturing surfaces, whose fabrication process is simple and time-saving. Here we propose a two-dimensional thermodynamic structure model based on the actual pore array laser-texturing surfaces, and four wetting states are defined in our model. By minimizing the Gibbs free energy, equilibrium contact angle and contact angle hysteresis representing wetting properties are calculated, and the effects of defined parameters (intrinsic contact angle θY, pore space b, and pore depth H) on wetting properties are analyzed in detail to find out the critical transition conditions among different wetting states. Besides, actual pore array laser-texturing surfaces are fabricated for further validation, and the wetting properties in measurement are found to be in good agreement with those in prediction, indicating that our model is credible and can be used to guide the design of the pore array superhydrophobic laser-texturing surfaces.
Discrete gas-kinetic scheme-based arbitrary Lagrangian–Eulerian method for moving boundary problems
Authors: Zhan Ningyu , Chen Rongqian , You Yancheng
Published: June 2021

In this work, a discrete gas-kinetic scheme (DGKS) based on the arbitrary Lagrangian–Eulerian (ALE) method is proposed for the simulation of moving boundary problems. The governing equations are the ALE-based Navier–Stokes equations, which are discretized using the finite volume method. Starting from a circular function-based Boltzmann equation, a grid motion term is introduced to obtain the Boltzmann equation in ALE form. Based on the moment relations and Chapman–Enskog analysis, the moment of particle velocity and distribution function are summed to obtain the fluxes. The DGKS expression in the ALE framework can then be derived. In this method, the flux at the cell interface can be calculated from the local solution of the Boltzmann equation, which is physically realistic and makes the algorithm more stable. As DGKS is based on a multidimensional particle velocity model, it is not necessary to use approximate values for the reconstruction process. In addition, DGKS can simultaneously handle inviscid and viscous fluxes when simulating viscous flow problems, resulting in a higher degree of consistency. Finally, several moving boundary examples are simulated to validate the ALE-DGKS method. The results show the algorithm was observed to achieve second-order accuracy and can solve moving boundary problems effectively.
Suppression of vortex-induced vibration of a cactus-inspired cylinder near a free surface
Authors: Wang Wei , Mao Zhaoyong , Song Baowei , Tian Wenlong
Published: June 2021

Bionic ribs inspired by those of a cactus are adopted in order to suppress the vortex-induced vibration (VIV) responses of cylinders located near free surfaces. The VIV responses of cactus-inspired cylinders located near free surface are investigated numerically. The range of the Reynolds number is 8.0 × 103 ≤ Re ≤ 5.6 × 104, and the range of the Froude number is 0.08 ≤ Fr ≤ 0.56. The distance between the cylinder and the free surface is 2D (D is diameter of the cylinder), and the cactus-inspired ribs with height ratios (Ks/D, where Ks is the height of the ribs) include 0.0 (M1), 0.025 (M2), 0.05 (M3), and 0.1 (M4). The VIV response of a smooth cylinder (M0) far from a free surface is used as a reference. Different ribs with height ratios have different effects on the VIV responses of cylinders located near free surfaces. The suppression effect of the bionic ribs on the VIV response is largest when Ks/D = 0.1 (M4). The maximum cross-flow amplitude ratio, the maximum in-line amplitude ratio, and the maximum mean drag coefficient of the cactus-inspired cylinder (M4) are 53.57%, 53.13%, and 49.21% lower than that of the smooth cylinder (M1). The cactus-inspired cylinders are easier to desynchronize from the lock-in region. The free surface causes the vortex phase transition to happen earlier. The free surface has a better suppression effect on VIV response in the high Froude number range. When the rib height ratio is small (M2, Ks/D = 0.025), the free surface enhances the VIV response. However, the VIV response is mainly affected by the ribs when the rib height ratio exceeds a certain value (Ks/D ≥ 0.05). When the cactus-inspired rib with height ratio increases, the critical Reynolds number of the vortex phase transition decreases. The free surface and the cactus-inspired ribs are conducive to dissipation of wakes and lead to decreases in the wake turbulence intensity. Because the cactus-inspired ribs can cause the separation line to develop away from the cylinder wall and effectively control the wake intensity, the VIV response of the cactus-inspired cylinder is suppressed effectively. For the cactus-inspired cylinder, galloping responses can be avoided in high-Reynolds-number range, and boundary-layer separation occurs at the top of the ribs. Unlike the boundary-layer separation process of the smooth cylinder (M1), the ribs of the cactus-inspired cylinder destroy the boundary layer, causing smaller vortices to be produced.
Main modes of runaway electron generation during a breakdown of high-pressure gases in an inhomogeneous electric field
Authors: Sorokin Dmitry A. , Beloplotov Dmitry V. , Tarasenko Victor F. , Baksht Evgeni Kh.
Published: June 2021

Using our recently proposed method, we have identified three modes of runaway electron generation. This method is based on the recording of a dynamic displacement current using a current collector. It makes it possible to unambiguously interpret the dynamics of ionization processes occurring at the stage of formation of a high-voltage nanosecond discharge in a strongly inhomogeneous electric field and dense gaseous media. Simultaneous and separate recording by the current collector of a runaway electron beam current and the dynamic displacement current as well as the recording of discharge characteristics and high-speed framing of plasma glow at the breakdown stage made it possible to interpret the runaway electron generation modes in terms of the rate of ionization processes. It has been shown how the reduced electric field strength, the gas kind, the design and material of a high-voltage cathode with a small radius of curvature, the amplitude and rise time of a voltage pulse as well as the delay in the onset of the explosive emission process at the cathode affect the implementation of one or another generation mode.
Solid-state electrochemical redox control of the optoelectronic properties for SrFeOx thin films
Authors: Yang Qian , Cho Hai Jun , Jeen Hyoungjeen , Ohta Hiromichi
Published: June 2021

By utilizing redox reactions, the physical properties of several transition metal oxides can be drastically changed, which is useful for developing multifunctional memory devices. Strontium iron oxide (SrFeOx), which exhibits a clear phase transition from antiferromagnetic insulator (x = 2.5) to helimagnetic metal (x = 3), is a good candidate for the active material in multifunctional memory devices. However, practical applications using previous demonstrations of redox reactions in SrFeOx are limited by the use of a liquid electrolyte due to the leakage problem. Here, we demonstrate solid-state electrochemical redox reaction in SrFeOx using a yttria-stabilized zirconia (YSZ) single-crystal substrate as the solid electrolyte. We fabricated the SrFeO2.5 film on the YSZ substrate and the applied electric current using Au electrodes. The phase gradually changed from SrFeO2.5 to SrFeO2.5+x and SrFeO3−x. The color of the film changed from yellowish-transparent to dark brown. Although the as-grown SrFeO2.5 film showed high resistivity (ρ > 101 Ω cm), the ρ dramatically decreased (∼10−2 Ω cm) with increasing the applied charge density. Simultaneously, the thermopower greatly decreased from ∼+200 to ∼−10 μV K−1. The present results would provide a design concept for future SrFeOx-based solid-state multifunctional memory devices.
Cultivating Confidence and Professionalism
Authors: Grimes Alisa , Schrode Nicole , Stober Rebecca , Wachowski Shannon
Published: June 2021

This chapter discusses the need for teachers to serve in formal leadership roles at all levels. In the process, professionalism is discussed as it pertains to the field of education. To expand their influence, teachers must also gain confidence and leadership skills. Steps to gaining these attributes are discussed, as well as how teachers can overcome imposter syndrome or other feelings of inadequacy preventing them from stepping into leadership roles. The chapter ends with a brief discussion about creating and maintaining work–life balance, along with tools to address teacher burnout. Discussion questions are provided to encourage further reflection or for use within a professional book study.
Influence of antral follicle count on in vitro embryo production, sexual precocity and conception rate of Senepol cattle
Authors: Fagundes Faria Ana Cláudia , Faria de Moraes Giovanna , Silva Pereira Leticia , Ribeiro Cunha Rodrigo , dos Santos Ricarda Maria
Published: June 2021

Context There are contradictory results concerning the relationship between antral follicle count (AFC) and reproductive traits for different breeds of cattle. Understanding this relationship could be useful to selecting animals for breeding. Aims We evaluated the effects of AFC on parameters related to in vitro embryo production (IVP), and the influence of AFC on sexual precocity and conception rate at first fixed timed artificial insemination (FTAI) of Senepol females. Methods Ovarian ultrasound was performed to count antral follicles, and females were classified as low AFC (≤22 follicles), intermediate AFC (23–36 follicles) or high AFC (>36 follicles). Expt 1 evaluated the influence of AFC on IVP, with data from 146 adult cows that were submitted to follicular aspiration. Expt 2 evaluated the influence of AFC on heifer sexual precocity, determined by the presence of a corpus luteum (n = 608), and on conception rate at first FTAI (n = 143). Key results High AFC cows had a greater (P < 0.0001) number of viable oocytes and cleaved embryos and a higher average number of embryos than low AFC cows (38.28 vs 9.92, 38.28 vs 7.75 and 9.34 vs 2.41, respectively). However, the conversion rate (total viable embryos per oocytes) was not affected (P = 0.46) by AFC category. High AFC heifers tended (P = 0.07) to be more sexually precocious than low AFC heifers (16.73% vs 9.47%). An influence of AFC or of AFC category on conception rate at first FTAI was not detected (P = 0.35 and 0.19, respectively). Conclusions Despite greater IVP in high AFC cows, the conversion rate of viable oocytes to IVP was not affected by AFC category. High AFC heifers tended to be more sexually precocious, although AFC did not influence the conception rate at first FTAI. Implications Oocyte quality is probably not influenced by AFC, but selection of animals according to AFC may improve the sexual precocity of the herd.
Transposon-mediated insertional mutagenesis unmasks recessive insecticide resistance in the aphid
Myzus persicae
Authors: Panini Michela , Chiesa Olga , Troczka Bartlomiej J. , Mallott Mark , Manicardi Gian Carlo , Cassanelli Stefano , Cominelli Filippo , Hayward Alex , Mazzoni Emanuele , Bass Chris
Published: June 2021

Significance

The ability to control damaging plant pests and vectors of animal disease is threatened by the emergence of insecticide resistance. Developing effective strategies to prevent, slow, or overcome resistance requires an understanding of the underlying genetic mechanisms. Here, we present an example of the evolution of insecticide resistance arising from transposable element–mediated disruption of a dominant insecticide-susceptible allele, resulting in expression of a recessive resistance allele and potent resistance. Our findings demonstrate how the adaptive potential of transposable elements can be revealed by environmental and genetic perturbation and that this can have profound and unexpected impacts on resistance. They also illustrate how combinations of mutations that individually confer no fitness benefit can interact to provide strong context-dependent fitness benefits.
Copper binding by a unique family of metalloproteins is dependent on kynurenine formation
Authors: Manesis Anastasia C. , Jodts Richard J. , Hoffman Brian M. , Rosenzweig Amy C.
Published: June 2021

Significance

Copper is particularly important in the metabolism of methanotrophs, methane-consuming bacteria that have potential applications in converting methane, a greenhouse gas, to useful fuels and chemicals. How methanotrophs and other bacteria acquire and distribute copper, which is toxic in excess, is not well understood. Here we identify and characterize a previously unknown copper-binding protein implicated in methanotroph copper homeostasis. This protein, MbnP, binds copper with an unusual coordination sphere that includes kynurenine, a tryptophan oxidation product that is produced in vivo by a partner protein, MbnH. MbnP is the founding member of a widespread protein family with potentially broad roles in microbial copper homeostasis.
Petrographic carbon in ancient sediments constrains Proterozoic Era atmospheric oxygen levels
Authors: Canfield Don E. , van Zuilen Mark A. , Nabhan Sami , Bjerrum Christian J. , Zhang Shuichang , Wang Huajian , Wang Xiaomei
Published: June 2021

Significance

Earth progressed from an oxygen-free planet at birth to the well-oxygenated planet we have today. Life enabled Earth’s oxygenation through the evolution of cyanobacteria, and the subsequent history of oxygen enabled further developments in the evolution of eukaryotic life; mammals, for example, need relatively high oxygen levels to breathe. The relationship between oxygen and life, however, is hampered by uncertainties in the history of oxygen concentrations, particularly during the middle of the Proterozoic Eon when eukaryote ecosystems were first emerging. We explore ancient organic matter cycling through Raman spectrographic analysis of nine geologic formations spanning 1 billion years of Proterozoic time. Our results, when combined with modeling, show that emerging eukaryote ecosystems were not limited by oxygen concentrations.
Identifying the origin of local flexibility in a carbohydrate polymer
Authors: Anggara Kelvin , Zhu Yuntao , Fittolani Giulio , Yu Yang , Tyrikos-Ergas Theodore , Delbianco Martina , Rauschenbach Stephan , Abb Sabine , Seeberger Peter H. , Kern Klaus
Published: June 2021

Significance

The monomer sequence dictates the structure and properties of natural polymers. Such a structure–property relationship is well known for polypeptides and polynucleotides but not for polysaccharides, the most abundant biopolymers on Earth. Here, we establish the structure–property relationship for a polysaccharide at the atomic level by determining molecular flexibility of carbohydrate chains with defined sequences. The chain flexibility can be engineered one linkage at a time by chemical substitution and conformation change, highlighting how the primary and secondary structures of a carbohydrate dictate its flexibility—a critical observable in the de novo design of carbohydrate materials. Our approach can be extended to establish the structure–property relationship at the atomic level of any molecule that can be electrosprayed.
On and off controls within dynein–dynactin on native cargoes
Authors: Sanghavi Paulomi , Kumar Pankaj , Roy Ankit , Madhusudhan M. S. , Mallik Roop
Published: June 2021

Significance

The dynein–dynactin nanomotor is required for vastly diverse cellular functions, including cell division and cargo transport. Why dynactin interacts separately with the dynein motor and with microtubules is poorly understood and controversial. Here we directly interrogate the function of native dynein–dynactin teams on single phagosomes extracted from cells after disrupting the above interactions in a targeted manner ex vivo. Perturbing the dynactin–dynein interaction reduces dynein’s on rate to microtubules. However, perturbing the dynactin–microtubule interaction increases dynein’s off rate markedly when dynein generates force against an optical trap. Our results therefore ascribe separable functions to different components within the dynein–dynactin machine and provide mechanistic insight into dynein–dynactin dysfunction.
Fusarium oxysporum f.sp. vasinfectum (Fusarium wilt).
Authors: Isakeit Thomas
Published: June 2021

F. oxysporum f.sp. vasinfectum causes significant crop losses in several of the main cotton-producing countries. The disease is widespread in the USA, the former Soviet Union (Menlikiev, 1962) and China. In Africa, Tanzania is the worst affected country (Hillocks, 1981). Although losses nationally may not be great, estimated for instance at 0.2% for the whole of the USA in 1989 (Blasingame, 1990), losses are much greater in localized areas and for individual farmers in areas where the disease is endemic. The presence of a pathogen in a field can exclude the planting of a variety with desirable agronomic characteristics (.e.g. yield) if it is susceptible to the pathogen.
Nugget formation analysis of Al/Steel clinch-resistance hybrid spot welding
Authors: Zhao Dewang , Ren Daxin , Song Gang , Zhao Kunmin , Zhang Zhaodong
Published: June 2021

A clinch-resistance hybrid spot welding method was presented to join Al and steel. The nugget formation was analysed via microstructure observation and numerical simulation. A cup section nugget was formed, and the melting zone was mainly formed at the nugget edge with a thin layer of interfacial intermetallic compounds. Numerical simulation results showed that peak contact stress on the steel/Al contact surface was located at the connection between the punch tip and die tips. Aa remarkable amount of heat was first generated at the nugget edge and then transferred to the centre, but the temperature at the edge was relatively low. Compared with traditional spot welding, a unique distribution of heat occurred during the welding process.
Recovery during and after a simulated multi‐day tennis tournament: Combining active recovery, stretching, cold‐water immersion, and massage interventions
Authors: Wiewelhove Thimo , Szwajca Sebastian , Busch Maximilian , Döweling Alexander , Volk Nicola Reiner , Schneider Christoph , Meyer Tim , Kellmann Michael , Pfeiffer Mark , Ferrauti Alexander
Published: June 2021

The aim of this study was to investigate the effects of a mixed‐method recovery intervention (MMR) consisting of active recovery, stretching, cold‐water immersion, and massage on physical, technical, physiological, and perceptual recovery during and after a five‐day simulated tennis tournament. Nine competitive male tennis players (age, 24.6±4.2 years) with national ranking positions (German Tennis Federation) and Universal Tennis Ratings between approximately 11–13 participated in two singles tennis tournaments, which were separated by a three‐month washout period. During the tournaments, participants played five two‐and‐a‐half‐hour competitive singles tennis match on five consecutive days. For the assignment to one of two groups, athletes were matched into homogeneous pairs according to their ranking. Then, within each pair, the players were randomly assigned to one of two groups. The first group performed MMR during the first tournament, whereas the other group used passive recovery (PAS). During the second tournament, recovery conditions were interchanged. Measures of physical and technical performance as well as physiological and perceptual responses (heart rate, blood lactate concentration, perceived exertion) were recorded during match‐play sessions. Furthermore, muscle soreness, perceived recovery state, blood markers, countermovement jump height (CMJ), and repeated sprint ability (RSA) were determined before, during, and after the five‐day tournament periods. Results showed significant changes over time (P < 0.05) in muscle soreness, perceived recovery state, creatine kinase, c‐reactive protein, insulin‐like growth factor 1, and countermovement jump height. However, no significant differences or recovery strategy x time interactions were noted either for tennis‐specific performance (e.g. number of total points won) or any other of the measured parameters between MMR and PAS (P > 0.05). In conclusion, the repeated use of MMR during and after a five‐day tennis tournament did not affect match performance, match load, or recovery from repeated days of tennis match play.
The molecular and epigenetic mechanisms of innate lymphoid cell (ILC) memory and its relevance for asthma
Authors: Verma Mukesh , Michalec Lidia , Sripada Anand , McKay Jerome , Sirohi Kapil , Verma Divya , Sheth Dipa , Martin Richard , Dyjack Nathan , Seibold Max A. , Knapp Jennifer R. , Tu Ting-Hui , O’Connor Brian P. , Gorska Magdalena M. , Alam Rafeul
Published: June 2021

Repetitive exposure of Rag1−/− mice to the Alternaria allergen extract generated a form of memory that elicited an asthma-like response upon a subthreshold recall challenge 3–15 wk later. This memory was associated with lung ICOS+ST2+ ILC2s. Genetic, pharmacologic, and antibody-mediated inhibition and adoptive transfer established an essential role for ILC2s in memory-driven asthma. ATAC-seq demonstrated a distinct epigenetic landscape of memory ILC2s and identified Bach2 and AP1 (JunD and Fosl2) motifs as major drivers of altered gene accessibility. scRNA-seq, gene knockout, and signaling studies suggest that repetitive allergenic stress induces a gene repression program involving Nr4a2, Zeb1, Bach2, and JunD and a preparedness program involving Fhl2, FosB, Stat6, Srebf2, and MPP7 in memory ILC2s. A mutually regulated balance between these two programs establishes and maintains memory. The preparedness program (e.g., Fhl2) can be activated with a subthreshold cognate stimulation, which down-regulates repressors and activates effector pathways to elicit the memory-driven phenotype.
Fabrication of 15NV− centers in diamond using a deterministic single ion implanter
Authors: Groot-Berning Karin , Jacob Georg , Osterkamp Christian , Jelezko Fedor , Schmidt-Kaler Ferdinand
Published: June 2021

Nitrogen vacancy (NV) centers in diamond are a platform for several important quantum technologies, including sensing, communication and elementary quantum processors. In this letter we demonstrate the creation of NV centers by implantation using a deterministic single ion source. For this we sympathetically laser-cool single

N

2

+

15

molecular ions in a Paul trap and extract them at an energy of 5.9 keV. Subsequently the ions are focused with a lateral resolution of 121(35) nm and are implanted into a diamond substrate without any spatial filtering by apertures or masks. After high-temperature annealing, we detect the NV centers in a confocal microscope and determine a conversion efficiency of about 0.6%. The 15NV centers are characterized by optically detected magnetic resonance on the hyperfine transition and coherence time.
Roadmap on bio-nano-photonics
Authors: Herkert Ediz , Slesiona Nicole , Recchia Martina Elisena , Deckert Thomas , Garcia-Parajo Maria F , Fantuzzi Eric Michele , Pruccoli Andrea , Ragupathy Imaiyan Chitra , Gudavičius Dominykas , Rigneault Hervé , Majer Jan , Zumbusch Andreas , Munger Eleanor , Brasselet Sophie , Jones Arwyn T , Watson Peter , Boppart Stephen A , Singh Vikramdeep , Borkar Saurabh , Quintela Rodriguez Frank E , Langbein Wolfgang , Petropoulos Vasilis , van Hulst Niek F , Maiuri Margherita , Cerullo Giulio , Brida Daniele , Troiani Filippo , Rozzi Carlo Andrea , Molinari Elisa , Vengris Mikas , Borri Paola
Published: June 2021

In the quest to decipher the chain of life from molecules to cells, the biological and biophysical questions being asked increasingly demand techniques that are capable of identifying specific biomolecules in their native environment, and can measure biomolecular interactions quantitatively, at the smallest possible scale in space and time, without perturbing the system under observation. The interaction of light with biomolecules offers a wealth of phenomena and tools that can be exploited to drive this progress. This Roadmap is written collectively by prominent researchers and encompasses selected aspects of bio-nano-photonics, spanning from the development of optical micro/nano-spectroscopy technologies for quantitative bioimaging and biosensing to the fundamental understanding of light–matter interaction phenomena with biomolecules at the nanoscale. It will be of interest to a wide cross-disciplinary audience in the physical sciences and life sciences.
The effect of FSP conditions towards microstructure and mechanical properties of the AA6082/AA8011 TIG-welded joint
Authors: Mabuwa Sipokazi , Msomi Velaphi
Published: June 2021

The friction stir processing (FSP) technique was employed on the AA6082-AA8011 TIG-welded joints to investigate the contribution of the processing conditions on the microstructure and mechanical properties of the processed joints. The TIG-welded joints were subjected to the FSP technique under normal and submerged conditions. The tests conducted included microstructural analysis, tensile, Vickers hardness and fracture surface analysis. The microstructural analysis of the normal FSP joints showed the minimum average grain size of 7.83 μm and maximum average of 9.25 μm, while the submerged FSP joints had a range of 6.33 μm to 4.86 μm. All the FSPed joints showed a great grain size refinement compared to the TIG-welded joints which had an average grain size range of 25.71 μm to 21.99 μm. The ultimate tensile strength (UTS) of the joints processed under normal conditions ranged between 87.14 MPa and 88.33 MPa while that of the submerged conditions ranged between 88.79 MPa and 91.56 MPa. The elongation range of the normal FSP joints was 22.71% to 24.28% while 24.08% to 28.81% was obtained from the submerged FSP joints. The TIG-welded joints had a UTS range of 80.27 MPa to 85.36 MPa with an elongation of 21.82% to 23.58% respectively. FSP improved both the tensile strength and the ductility of the joints with the submerged conditions giving best improved results. The fracture surface morphology revealed a ductile failure mode for all the specimens. The TIG-welded joints had a maximum hardness range of 56 HV to 60 HV, while that of the normal and submerged FSP joints ranged between 54 HV and 57 HV, and between 60 HV and 65 HV, respectively. The application of Normal FSP on the TIG welded joints slightly compromised the hardness of the joints under normal conditions but improved under SFSP due to rapid cooling.
Pressure induced mechanical, opto-electronics, and transport properties of ZnHfO3 oxide for solar cell and energy harvesting devices
Authors: Mahmood Asif , Ramay Shahid M , Al-Masry Waheed , Al-Zahrani Ateyah A , Shaikh H M
Published: June 2021

Based on the density functional theory, we systematically investigate the effect of pressure on the mechanical, optoelectronic, and transport properties of ZnHfO3. The pressure has been employed up to 30 GPa in a step-size of 10 GPa. A slight variation in the lattice constant and Bulk modulus have been observed at the applied pressure steps. The electronic properties are significantly tuned by applying pressure. The calculated bandgap values slightly increase with increasing the pressure and its values start to decrease after the critical pressure of 20 GPa. More interestingly, a transition from indirect to direct band has been observed at the critical pressure. This transition of the bandgap is also justified by studying the optical properties like dielectric constant, refraction, and absorption at different pressure. Furthermore, we studied the electronic transport properties in terms of electrical conductivity, thermal conductivity, See-beck coefficient, and power factor at temperature (300–800 K). The calculated lattice thermal conductivities are low while the electrical conductivities and Seebeck coefficients are high at all pressure. Thus, the properties of the ZnHfO3 show high potential for thermoelectric applications.
Equivalence of categories between coefficient systems and systems of idempotents
Authors: Lanard Thomas
Published: June 2021

The consistent systems of idempotents of Meyer and Solleveld allow to construct Serre subcategories of

Rep
R

⁡
(
G
)

\operatorname {Rep}_R(G)

, the category of smooth representations of a

p
p

-adic group

G
G

with coefficients in

R
R

. In particular, they were used to construct level 0 decompositions when

R
=

Z

¯

ℓ

R=\overline {\mathbb {Z}}_{\ell }

,

ℓ
≠
p

\ell \neq p

, by Dat for

G

L

n

GL_{n}

and the author for a more general group. Wang proved in the case of

G

L

n

GL_{n}

that the subcategory associated with a system of idempotents is equivalent to a category of coefficient systems on the Bruhat-Tits building. This result was used by Dat to prove an equivalence between an arbitrary level zero block of

G

L

n

GL_{n}

and a unipotent block of another group. In this paper, we generalize Wang’s equivalence of category to a connected reductive group on a non-archimedean local field.