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Owing to the existence of high-order motion parameters and vertical velocity, severe range-azimuth coupling and two-dimensional spatial variability of the imaging parameters degrade the image quality of high-squint synthetic aperture radar (SAR) mounted on manoeuvring platforms. To accommodate these issues, a novel sub-aperture SAR imaging algorithm based on keystone transform (KT) and azimuth sub-region deramp is proposed. In the range dimension processing, a correction function is constructed based on the scene centre to realise non-spatial-variant range cell migration (RCM) correction and range-azimuth decoupling, and then the residual spatial-variant RCM is removed by the KT. In the azimuth dimension processing, considering the impact of the range distortion on the azimuth modulated phase, accurate analytical formula of the signal in the azimuth time domain is deduced. On this basis, a fast azimuth compression method based on the azimuth sub-region deramp is proposed, and the theoretical effective imaging area is analysed. The theoretical analysis and the simulations show that the proposed imaging algorithm has high computational efficiency and can effectively expand the imaging area of high-squint SAR mounted on manoeuvring platforms.

For the impacting-freezing process of the droplet on cold surfaces, more studies have focused on stationary surfaces, while moving surfaces have received less attention. Here, a three-dimensional numerical model based on the VOF model and the Solidification/Melting model is established to numerically study the impacting-freezing process of the droplet on a lateral moving cold superhydrophobic surface, and focusing on the morphology evolution of the droplet and the initial freezing location. For the lateral moving surface, five different morphology distributions were observed during the impacting-freezing process of the droplet: full rebound, near full rebound, partial rebound, near full adhesion and full adhesion. The initial freezing location of the droplet preferentially appears on the upstream side of the droplet. The freezing on the downstream side of the droplet lags behind that of the upstream side due to the cooling effect of the cold surface, and the lagging effect is strongly influenced by the cold surface temperature. Moreover, the effects of cold surface temperature, supercooling degree and impacting Weber number on the spreading factor during the impacting-freezing process of the droplet are also discussed. The effect of the cold surface temperature on the spreading factor is greater than that of the supercooling degree. And a unified morphology distribution map of rebound and adhesion of the droplet is plotted based on the weighted average temperature and the impacting Weber number, which can show the competitive relationship between droplet impact hydrodynamics and droplet solidification.

A two-dimensional Lattice Boltzmann model was established to study the dynamic physical process of frost growth on a cold flat surface. It is verified that the theoretical results are in good agreement with the experiment data with better accuracy. The frost morphology is explored by showing two-dimension density distribution with different cold surface temperatures. The results also include dynamic characteristics of frost properties such as thickness, deposition weight, volume fraction, density, temperature. According to the results, it is found that the nearer it is from the cold flat plate, the larger of frost crystal volume fraction and density are. The frost surface temperature increases rapidly at the early period of frosting and then increases gradually towards the triple point temperature of the water. The frost internal temperatures rise in a linear tendency with the frost thickness and decrease at the same frost layer location with frost growth. Super-saturation degree of moist air has non-negligible effect on frost growth parameters such as frost thickness, frost crystal deposition mass, frost deposition rate and frost crystal volume fraction.

A droplet can bounce in a short contact time after impacting on superhydrophobic surfaces (SHSs), which is of benefit to the applications like anti-icing, anti-frosting and self-cleaning. In this study, we numerically investigate the fast droplet bouncing induced by asymmetric spreading on the concave SHS with a trapezoidal cross-section and focus on the droplet morphology evolution and contact time variation. A preferential transport at the both sides of the droplet from the inclined part to the flat part will occur because of the concave structure feature. The droplet will exhibit asymmetric spreading behavior. Moreover, the effects of structure parameters and impact velocity on the droplet contact time are explored. Within this concave structure, the droplet contact time is less influenced by the impact velocity and more influenced by the structural parameters. The presence of the tangential momentum can enhance the droplet asymmetric spreading, but it is not always beneficial to the droplet contact time reduction. Therefore, there will be an optimal structure to achieve the minimum droplet contact time. A concave SHS structure with the structure width w = 1–1.2r and the inclination angle of 45° is a more desirable choice, which is expected to reduce the droplet contact time by 40~45%.

TNFR-associated factors (TRAFs) and receptor-interacting protein kinases (RIPKs) are important immunological linker molecules in mammals and play important roles in the TNFα, TLR and IFN signaling pathways. However, the evolutionary origins of these genes in vertebrates have not previously been described in lampreys. In this study, we searched the genomes of Lampetra japonicum, Lethenteron reissneri, and Petromyzon marinus for genes encoding trafs and ripks and performed homologous sequence alignment, phylogenetic tree, functional domain, conserved motif, gene structure, and synteny analyses to determine their evolutionary relationships. The distribution of the lamprey traf and ripk families and the immune response of the gene families in lampreys stimulated by different pathogens were also demonstrated, suggesting a role of structural changes in expression and functional diversification. Additionally, the dual luciferase reporter gene assay showed that the addition of exogenous immunomodulator (TNFα or IFN) to the overexpression of LjLRIPK1a or LjTRAF3/6 significantly downregulated NF-κB or ISRE activation. LjRIPK1a can significantly enhance caspase-8 activity, and overexpression of LjRIPK1a or LjTRAF3a/6 in HEK293T cells results in cell apoptosis. In summary, this study makes an important contribution to the understanding of the traf and ripk gene families in different vertebrates. Our results also provide new evidence for the evolution of vertebrate TRAFs and RIPKs and their impacts on immune regulation.

We demonstrate that a field-effect transistor (FET) made of few-layer black phosphorus (BP) encapsulated in hexagonal boron nitride (h-BN) in vacuum exhibits a room-temperature hole mobility of 5200 cm2/(Vs), being limited just by the phonon scattering. At cryogenic temperatures, the FET mobility increases up to 45 000 cm2/(Vs), which is five times higher compared to the mobility obtained in earlier reports. The unprecedentedly clean h-BN–BP–h-BN heterostructure exhibits Shubnikov–de Haas oscillations and a quantum Hall effect with Landau level (LL) filling factors down to v = 2 in conventional laboratory magnetic fields. Moreover, carrier density independent effective mass of m* = 0.26 m0 is measured, and a Lande g-factor of g = 2.47 is reported. Furthermore, an indication for a distinct hole transport behavior with up- and down-spin orientations is found.

The navigation, positioning and imaging of blind area (unknown area) has always been one of the research focuses in the field of unmanned and intelligent development. It is known that the choice of the grid where the sub-images are computed is a key point of the fast factorized back projection (FFBP, can be adopted to obtain images with arbitrary trajectories) algorithm. The grid partition of blind area may result in the loss of information in the imaging area due to the unpredictability. The same loss also exists when the angle of existence deviates from the ideal imaging angle. In this paper, a new echo signal processing method for blind area imaging of synthetic aperture radar (SAR) is proposed. It is presented that a method of describing irregular echoes by using generalized array. The definition and operation principle of generalized array are introduced, as well as the relationship between the echo described by generalized array and traditional echo. Finally, the simulation results show that the proposed method is beneficial to imaging processing, and the method has great significance to range migration correction in frequency domain and imaging grid generation of BP algorithm.

A numerical investigation of frost growth on a cold flat surface was presented based on two-dimensional Lattice Boltzmann model. This model has been validated to have less prediction error by past experiments. According to the results, it is shown that average frost density appears different at an increasing rate at different frosting stages. In addition, cold surface temperature has great influence on frost growth parameters such as frost crystal deposition mass, frost deposition rate, and frost crystal volume fraction. It was found that the frost crystal deposition mass, frost crystal volume, and the deposition rate first increase rapidly, then gradually slow down, finally remaining unchanged while the cold surface temperature decreases. The further away from the cold surface, the more sparser the frost layer structure becomes due to the smaller frost crystal volume fraction.

We investigate the re-entrant tetragonal phase in the iron-based superconductor Ba 0 .76 K 0.24 Fe 2 As 2 by DC magnetization and thermoelectrical measurements. The reversible magnetization confirms by a thermodynamic method that the spin alignment in the re-entrant C 4 phase is out-of-plane, in agreement with an itinerant double- Q magnetic order [Allred et al., Nat. Phys. 12 , 493 (2016)]. The Nernst coefficient shows the typical unusually large negative value in the stripe-type spin density wave (SDW) state owing to the Fermi surface reconstruction associated with SDW and nematic order. At the transition into the re-entrant C 4 tetragonal phase it hardly changes, which could indicate that instead of a complete vanishing of the associated charge order, the spin reorientation could trigger a redistribution of the charges to form a secondary charge order, e.g. in form of a chequerboard-like pattern that no longer breaks the rotational C 4 symmetry.

We fabricate high-mobility p-type few-layer WSe_{2} field-effect transistors and surprisingly observe a series of quantum Hall (QH) states following an unconventional sequence predominated by odd-integer states under a moderate strength magnetic field. By tilting the magnetic field, we discover Landau level crossing effects at ultralow coincident angles, revealing that the Zeeman energy is about 3 times as large as the cyclotron energy near the valence band top at the Γ valley. This result implies the significant roles played by the exchange interactions in p-type few-layer WSe_{2}, in which itinerant or QH ferromagnetism likely occurs. Evidently, the Γ valley of few-layer WSe_{2} offers a unique platform with unusually heavy hole carriers and a substantially enhanced g factor for exploring strongly correlated phenomena.

We report measurements of the specific heat and electrical resistivity of $\mathrm{C}{\mathrm{a}}_{3}{(\mathrm{I}{\mathrm{r}}_{0.91}\mathrm{C}{\mathrm{o}}_{0.09})}_{4}\mathrm{S}{\mathrm{n}}_{13}$ in comparison to $\mathrm{C}{\mathrm{a}}_{3}\mathrm{I}{\mathrm{r}}_{4}\mathrm{S}{\mathrm{n}}_{13}$. The Co substitution was chosen to suppress the structural anomaly ${T}^{*}=38\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ reported in $\mathrm{C}{\mathrm{a}}_{3}\mathrm{I}{\mathrm{r}}_{4}\mathrm{S}{\mathrm{n}}_{13}$. While the superconducting transition temperature of $\mathrm{C}{\mathrm{a}}_{3}{(\mathrm{I}{\mathrm{r}}_{0.91}\mathrm{C}{\mathrm{o}}_{0.09})}_{4}\mathrm{S}{\mathrm{n}}_{13}$ is slightly higher than in the stoichiometric parent compound $\mathrm{C}{\mathrm{a}}_{3}\mathrm{I}{\mathrm{r}}_{4}\mathrm{S}{\mathrm{n}}_{13}$, and it displays a stronger superconducting coupling strength, the absence of a structural phase transition allows us to determine the spectral distribution of phonon states and its relation to superconductivity. The phonon density of states $F$(\ensuremath{\omega}) and the spectral electron-phonon scattering function ${{a}_{tr}}^{2}F(\ensuremath{\omega})$ are determined by deconvolution of the specific heat and electrical resistivity, respectively. A dominant mode appears in both histograms at $\ensuremath{\hbar}\ensuremath{\omega}=12\phantom{\rule{0.16em}{0ex}}\mathrm{meV}$, which indicates that this phonon mode is responsible for the superconductivity in $\mathrm{C}{\mathrm{a}}_{3}{(\mathrm{I}{\mathrm{r}}_{0.91}\mathrm{C}{\mathrm{o}}_{0.09})}_{4}\mathrm{S}{\mathrm{n}}_{13}$. The data suggest that superconductivity in this material class can be conclusively explained within a conventional strong -coupling phonon-mediated scenario.

The hole doped Fe-based superconductors $\mathrm{B}{{\mathrm{a}}_{1}}_{\ensuremath{-}x}{A}_{x}\mathrm{F}{\mathrm{e}}_{2}\mathrm{A}{\mathrm{s}}_{2}$ (where $A=\mathrm{Na}$ or K) show a particularly rich phase diagram. It was observed that an intermediate reentrant tetragonal phase, in which the ${C}_{4}$ fourfold rotational symmetry is restored, forms within the orthorhombic antiferromagnetically ordered stripe-type spin density wave state above the superconducting transition [S. Avci et al., Nat. Commun. 5, 3845 (2014); A. E. B\"ohmer et al., Nat. Commun. 6, 7911 (2015)]. A similar intermediate phase was reported to appear if pressure is applied to underdoped $\mathrm{B}{{\mathrm{a}}_{1}}_{\ensuremath{-}x}{\mathrm{K}}_{x}\mathrm{F}{\mathrm{e}}_{2}\mathrm{A}{\mathrm{s}}_{2}$ [E. Hassinger et al., Phys. Rev. B 86, 140502(R) (2012)]. Here we report data of the electric resistivity, Hall effect, specific heat, and the thermoelectric Nernst and Seebeck coefficients measured on a $\mathrm{B}{\mathrm{a}}_{0.85}{\mathrm{K}}_{0.15}\mathrm{F}{\mathrm{e}}_{2}\mathrm{A}{\mathrm{s}}_{2}$ single crystal under pressure up to 5.5 GPa. The data reveal a coexistence of the intermediate phase with filamentary superconductivity. The Nernst coefficient shows a large signature of nematic order that coincides with the stripe-type spin density wave state up to optimal pressure. In the pressure-induced intermediate phase the nematic order is removed, thus confirming that its nature is a reentrant tetragonal phase.

Microstructure, mechanical properties, and wear resistance of B-bearing high-speed steel (HSS) roll material containing 0.90-1.00% C, 1.3-1.5% B, 0.8-1.5% W, 0.8-1.5% Mo, 4.6-5.0% Cr, 1.0-1.2% V, and 0.15-0.20% Ti were studied by means of the optical microscopy (OM), the scanning electron microscopy (SEM), x-ray diffraction (XRD), hardness, impact toughness, and pin-on-disk abrasion tests. The results showed that as-cast structure of B-bearing HSS consisted of α-Fe-, M23(B,C)6-, M3(B0.7C0.3)-, and M2(B,C)-type borocarbides, a small quantity of retained austenite, and a small amount of TiC. The hardness and impact toughness values of as-cast B-bearing HSS reached 65-67 HRC and 80-85 kJ/cm2, respectively. There were many M23(B,C)6-precipitated phases in the matrix after tempering, and then, with increasing temperature, the amount of precipitated phases increased considerably. Hardness of B-bearing HSS gradually decreased with the increasing tempering temperature, and the change of tempering temperature had no obvious effect on impact toughness. B-bearing HSS tempered at 500 °C has excellent wear resistance, which can be attributed to the effect of boron.

We demonstrate that encapsulation of atomically thin black phosphorus (BP) by hexagonal boron nitride (h-BN) sheets is very effective for minimizing the interface impurities induced during fabrication of BP channel material for quantum transport nanodevices. Highly stable BP nanodevices with ultrahigh mobility and controllable types are realized through depositing appropriate metal electrodes after conducting a selective etching to the BP encapsulation structure. Chromium and titanium are suitable metal electrodes for BP channels to control the transition from a p-type unipolar property to ambipolar characteristic because of different work functions. Record-high mobilities of 6000 $cm^2V^{-1}s^{-1}$ and 8400 $cm^2V^{-1}s^{-1}$ are respectively obtained for electrons and holes at cryogenic temperatures. High-mobility BP devices enable the investigation of quantum oscillations with an indistinguishable Zeeman effect in laboratory magnetic field., Comment: 14 pages, 3 figures

We investigate the importance of superconducting order parameter fluctuations in the 122 family of Fe-based superconductors, using high-resolution specific heat and thermal expansion data of various $\mathrm{B}{\mathrm{a}}_{1\ensuremath{-}x}{\mathrm{K}}_{x}\mathrm{F}{\mathrm{e}}_{2}\mathrm{A}{\mathrm{s}}_{2}$ single crystals covering a large range of the phase diagram from the strongly underdoped to the overdoped regime. By applying scaling relations of the $3d\ensuremath{-}\mathrm{XY}$ and the $3d\ensuremath{-}\text{lowest-Landau-level}\phantom{\rule{0.28em}{0ex}}(3d\ensuremath{-}\mathrm{LLL})$ fluctuation models to data measured in different magnetic fields, we demonstrate that a strong increase of the critical fluctuation regime is responsible for the transition broadening in magnetic fields, which is a direct consequence of a magnetic-field-induced finite-size effect due to a reduction of the effective dimensionality by a decreasing magnetic length scale related to the mean vortex separation and the confinement of quasiparticles in LLL. The fluctuations are stronger in the underdoped and overdoped regimes and appear to be weakest at optimal doping.