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The Chang’e-4 (CE-4) probe, which includes a lander and a rover, was successfully landed in Von Kármán crater inside the South Pole-Aitken basin on January 3, 2019. Landing site mapping and topographic analyses have been performed at different scales using orbital, descent and ground data to support mission operations and various scientific investigations. We produced a 0.9 m-resolution seamless digital orthophoto map (DOM) mosaic of the CE-4 landing site region covering 51 km × 30 km using 100 Lunar Reconnaissance Orbiter Camera (LROC) Narrow-Angle Camera (NAC) images. Within an area of 3.2 km × 3.0 km of the the DOM around the lander, more than 11,000 craters with diameter greater than 5 m have been identified and measured. A 0.03 m- resolution DOM, which covers an area of 211 m × 187 m, was generated using descent images, and has been used as one of the base maps for overall rover traverse planning. During surface operations, local DEMs with 0.02 m resolution are routinely produced and topographic analysis have been performed at each waypoint using Navcam images and at some locations using Pancam images, to support waypoint-to-waypoint path planning, science target selection and scientific investigations.

For KDP and 70%-DKDP crystals, knowledge of thermal-stress distribution induced by weak absorption effect is crucial for their applications, especially in high-power laser systems. Based on photo-thermal common-path interferometry (PCI) technique, the correlations of weak absorption effect with different crystal orientations were systematically evaluated at 1064 nm. An obviously anisotropic property is demonstrated, and a similar pattern of z > x > I > II is also represented for KDP and 70%-DKDP crystals. More importantly, crystal uniformity could be reflected by the weak absorption results, indicating that PCI method could be considered as a novel way to identify the crystal quality. Meanwhile, Thermal parameters including thermal expansion and thermal conductivity were obtained. Using the finite-element method (FEM), the temperature gradients and thermal-stresses along z and x-cut samples were distinctly explored, implying that the corresponding distributions are mainly attributed to crystal orientations. Importantly, another fundamental factor is confirmed that the variation of deuterium content could influence the behaviors of temperature gradients and thermal-stresses distributions. Thus, taking advantage of PCI and FEM as a new approach is more conducive to better understanding the mechanism of laser-matter interactions.

Mercury entrapment in a porous material after mercury intrusion porosimetry (MIP) test is widely reported, yet the characterization of the entrapped mercury remains unclear. This study reported an experimental investigation on the entrapped mercury in a porous cement paste with/without surface-conformance control determined by X-ray computed tomography (X-CT). MIP tests were performed under three different maximum intrusion pressures. Results show that the surface-conformance control can substantially depress the first rise of throat size distributions and lower the threshold throat sizes. The entrapped mercury drops can be easily traced by X-CT due to the high mass attenuation coefficient of mercury. Both the entrapped and released mercury drops only occupy the limited volume fraction of the intruded pores. The surface conformance can decrease the mercury volume released from the pores. The findings of this study provide insights in better pore structure characterization of porous cement-based materials.

Short-term wind speed forecasting plays an important role in wind power generation and considerably contributes to decisions regarding control and operations. In order to improve the accuracy of wind speed forecasting, a large number of prediction methods have been proposed. However, existing prediction models ignore the role of data preprocessing and are susceptible to various limitations of the single individual model that can lead to low prediction accuracy. In this study, a developed combined model is proposed, including complete ensemble empirical mode decomposition with adaptive noise—a multi-objective grasshopper optimization algorithm based on a no-negative constraint theory—and several single models, including four neural network models and a linear model, to achieve accurate prediction results. The novel combined model considers the linear and nonlinear characteristics of the sequence, successfully overcomes the limitations of the single model, and obtains accurate and stable prediction results. In order to test the performance of combined model, the wind speed sequence of a wind farm from China is used for experiments and discussions. The results of the experiments and discussions show that the novel combined model has better forecasting performance than traditional prediction models.

LuGdVO3 was obtained by annealing the LuGdVO4 crystal at 1500 °C under vacuum condition. The X-ray fluorescence analysis method was used to measure the concentrations of Lu and Gd elements in LuGdVO4. The XRD result indicated that LuGdVO3 was the orthorhombic structure with space group Pbnm. The Raman spectrum of LuGdVO3 was investigated at room temperature. The chemical states and local symmetry of the LuGdVO3 crystal have been determined by XPS and XANES. It was found that the presence of different chemical forms of V evolved with annealing treatment, and the VO6 unit in the LuGdVO3 crystal was distorted octahedron. During the annealing process at high temperature under vacuum condition LuGdVO4 can be gradually translated to LuGdVO3 with decreasing lattice oxygen in the crystal lattice. Keywords: Lu0.5Gd0.5VO3 crystal, Annealing, XPS, XANES

An innovative stiffened circular hollow section (CHS) X-joint is introduced herein, which has been used in offshore long-span transmission towers due to its higher bearing capacity in comparison with traditional CHS X-joint. A total of 15 specimens are employed for the experimental study to gain insight into its mechanical characteristics. Corresponding finite element (FE) analysis is thus conducted. The numerical results are compared with that by tests, and a good agreement is found, which verifies the validity of the setup in the finite element modelling and analysis. By using the settings, a total of 480 joints are numerically modelled and corresponding load-displacement curves and ultimate bearing capacities are obtained by FE analysis. Parametric sensitive study results show that the bearing capacities of corresponding unstiffened X-joint and chord rings could be used for predicting the strength of stiffened X-joints. The predicted results are shown to be in good agreement with that from numerical and experimental studies, and the equations proposed for prediction are applicable for a wide range of joint parameters. In this survey, the stiffened joint is observed to provide strength enhancement up to 811% in comparison with the traditional unstiffened X-joint, which proves that the stiffening method employed herein is capable of improving the bearing capacity greatly.

Second-order nonlinear optics (NLO) is the foundation of frequency conversion for the generation of coherent light at frequencies where lasers have no emissions or operate poorly. The prerequisite for NLO materials is noncentrosymmetric symmetry that can generate an effectively non-counterbalanced spontaneous electronic polarization. Here, we propose that this material restriction can be broadened by controlling the electron distribution with a local internal electrostatic field (IEF), and we demonstrate artificially created and manipulated second harmonic generation (SHG) in a centrosymmetric optical material, a superimposed Co2+- and Mo6+-doped BiVO4 thin film with 2/m point group symmetry, where a homojunction producing tunable effective polarization is formed. The SHG was characterized and tuned by IEF. This work breaks the structural symmetry constraint on NLO materials. Besides, the phase-matching-like condition was realized for the further improvement of the efficient frequency conversion. Because polarization is also a prerequisite for many other functions besides SHG, we believe that this work should provide some inspiration for the further development of optoelectronic, photonic, and electronic materials.

Ultra high toughness cementitious composites suitable for spraying (sprayed UHTCCs) is characterized by strain-hardening property under direct tensile stress with tight crack-control ability. It has a great potential in the application of repairing and retrofitting cracked or corroded concrete structures. The utilization efficiency of sprayed UHTCC is significantly affected by the integrity of the repair or strengthening system, which depends on the interfacial bonding behavior between the sprayed UHTCC and concrete substrate. A Type L934 orthogonal experiment and scanning electron microscope (SEM) observation were performed to investigate the bond behavior between sprayed UHTCC and concrete substrate, where three factors, namely sprayed direction, surface roughness of concrete substrate, and application of primer, were taken into consideration with three test levels for each of the former two factors and two levels for the other factor provided. The results demonstrated that the spraying direction had a significant influence on the bond splitting tensile strength and a quite significant influence on the interfacial shear strength between sprayed UHTCC and concrete substrate, and the surface roughness of concrete substrate had significant influence on the interfacial shear strength but not much significant influence on the bond splitting tensile strength. It had little influence on the bond behavior between sprayed UHTCC and concrete substrate whether a thin layer of primer, which contained the same matrix of sprayed UHTCC without polyvinyl alcohol (PVA) fibers, was adopted or not.

TeO–B2O3–BaO glasses with different compositions were prepared by the conventional melt-quenching technique. The spectral properties of Tm3+/Ho3+ co-doped TeO–B2O3–BaO glasses with different doping concentrations were studied. In order to analyze the spectroscopic properties in detail, the Judd–Ofelt intensity parameters, spontaneous radiative probabilities, branching ratios, absorption and emission cross-sections, and gain coefficient spectra were calculated using Judd–Ofelt and McCumber theory based on the absorption and emission spectra. Meanwhile, the optimal doping concentration was determined as Tm2O3: 1.0 mol% and Ho2O3: 1.0 mol%. The results show that Tm3+/Ho3+ co-doped TeO–B2O3–BaO glass is an ideal mid-infrared laser gain medium.

Ernzerhof (HSE) hybrid functional approximations based on the density functional theory (DFT) method were applied to investigate the electronic band structures of SnTe. First principles calculations indicate that Ag substitution in SnTe could effectively modify the valence band structures and decrease the energy separation between valence bands, ΔEVBL-Σ, which will enhance the Seebeck coefficient. All the fabricated Ag doped SnTe samples show the same crystal structure as cubic SnTe. Compared to the pure SnTe sample, the Ag doped ones exhibit greatly enhanced thermoelectric performance, especially at high temperatures, with the highest figure-of-merit of around 1.35 achieved at 900 K, by concurrent optimization of the electrical and thermal transport properties.

Laser damage threshold (LDT) is critical for optical devices in high-intensity laser applications. Understanding the influence mechanism of a high-intensity laser on optical materials is principal for improving the materials’ LDTs. Here, the LDT of La3Ga5.5Nb0.5O14 (LGN) crystals, the most promising nonlinear optical material for mid-infrared optical parametric chirped-pulse amplification (OPCPA), were studied, and its laser damage mechanism was elucidated. Oxygen vacancies in different ligands have important and distinct effects on LDTs and introduce defect levels, playing primary roles in the reduction of LDTs by the absorption of electrons in the conduction bands. The formation of F-centers also decreases LDTs via two-photon absorption. In addition, the linear absorption of free electrons in the conduction bands contributes more than the two-photon absorption, induced by the defect level, in the nanosecond laser damage process. By annealing in optimized conditions, the 0% laser damage probability of the LGN crystals was measured up to 13.1 J/cm2, which is a 24% improvement compared with that of the as-grown sample, and the highest of the mid-infrared nonlinear optical crystals. The results can not only lead to further improvements in the laser amplification properties in OPCPA systems but also inspire further studies on the application of optical materials in high-intensity lasers.

Combined model theory has been widely used to forecast the time series problems that are often nonlinear, nonstationary and irregular. Current forecasting models based on combined models theory could adapt to some time series data and overcome some disadvantages of the single models. However, in previous studies, most forecasting models have just focused on improving the accuracy or stability. Nevertheless, for an effective forecasting model, considering only one criterion or rule (stability or accuracy) is insufficient. In this paper, a novel forecasting system, called non-dominated sorting genetic algorithm III combined system with three objective functions, was proposed and successfully employed to solve the predicament of electricity load forecasting which demands to obtain both high accuracy and strong stability as an example. Both stability and accuracy of our proposed combined system are superior to the model compared which showed in the experiment results.

Large-scale ground source heat pump systems (GSHPs) are increasingly used for space heating and cooling. In comparison to small-scale GSHPs, large GSHPs are often coupled with hundreds of borehole heat exchangers (BHE), which are more susceptible to significant ground temperature changes due to the intense thermal interactions between the BHE. In this study, we developed a new model to optimize the operation of large-scale GSHPs to mitigate the underground heat/cold accumulation. The Daxing Airport GSHP system, containing 10497 BHE, making it the largest GSHP system in the world, was selected as the target for performance optimization. Four key parameters were optimized, including the cooling/heating starting sequence, operation continuity, thermal load variability, and partition mode. Our results revealed that extreme cold accumulation mainly exists between the BHE arrays, rather than inside a single array. We recommend that spacing of adjacent BHE arrays should be greater. Meanwhile, an operational sequence of cooling, with intermittent operation and constant thermal load, is also suggested. In comparison, the partition mode only lowers the thermal anomaly inside the BHE array. Our findings imply that for large-scale GSHPs, the distance between BHE arrays is the most critical factor impacting performance, which differs from small-scale GSHPs.

In recent years, incorporating external knowledge for response generation in open-domain conversation systems has attracted great interest. To improve the relevancy of retrieved knowledge, we propose a neural entity linking (NEL) approach. Different from formal documents, such as news, conversational utterances are informal and multi-turn, which makes it more challenging to disambiguate the entities. Therefore, we present a context-aware named entity recognition model (NER) and entity resolution (ER) model to utilize dialogue context information. We conduct NEL experiments on three open-domain conversation datasets and validate that incorporating context information improves the performance of NER and ER models. The end-to-end NEL approach outperforms the baseline by 62.8% relatively in F1 metric. Furthermore, we verify that using external knowledge based on NEL benefits the neural response generation model.

The birefringent crystals capable of modulating the polarization of lights are of the current research interests. Although many oxide crystals have been discovered and widely used in UV and visible regions, the birefringent crystals in the infrared (IR) region are still rare. Herein, two new chalcogenides, K

We reported a high repetition rate diode-pumped alexandrite femtosecond laser using a simple linear cavity. Laser emission spectrum was as broad as ∼20 nm by inserting a 0.5-mm-thick quartz birefringent plate as a spectral modulation component. Pulse duration as short as few-cycle 36 fs with the repetition rates of 2.48 GHz was measured at pump power of 17 W. To the best of our knowledge, this is the shortest pulse duration achieved in the alexandrite lasers.

A new noncentrosymmetric (NCS)

A new borate fluoride, Li3CaB2O5F, has been synthesized. It features a sandwich-like structure with the adjacent [Li3OF]∞ and [CaO]∞ layers connected by the weak Li-O bonds and the [B2O5] dimers. Interestingly, Li3CaB2O5F has large ionic conductivity, which is attributed to the diverse and wide Li-ion diffusion pathways.

Polymorphic α- and β-BaTi(IO

Introduction of Pb

Two new halogen-rich ortho-borates, Ba

Copper has been incorporated into Ni-Fe alloys to form a series of ternary NiFeCu alloy catalysts with molar ratio of Cu/Fe varying from 0 to 1.5, which were tested in dry reforming of methane (DRM) at 923 K and atmospheric pressure with a CH4 /CO2 ratio of 1. XRD, TPR-H2 and FE-TEM measurements confirm the formation of Ni-Fe-Cu alloys with particle size of 5.0-5.7 nm. The Ni3 Fe1 Cu1 -Mgx Aly Oz (2.6 wt% Cu) shows the highest carbon resistance with only 5.0 % carbon by thermogravimetric analysis. Importantly, XPS analyses complemented with XAFS demonstrate that doping an appropriate quantity of Cu to form stable trimetallic alloy enhances the interaction between Ni and Fe, thus inhibiting Fe segregation and reducing carbon deposition. However, doping excessive Cu (3.9 wt%) weakens the Ni-Fe bond, preventing Fe from providing labile oxygen to Ni sites, which is unfavorable for carbon elimination.

IR nonlinear-optical (NLO) crystal is the important device in IR laser technology. Nevertheless, the application of most IR NLO crystals in high-power lasers is always limited by the low laser damage threshold (LDT), which is mainly caused by the narrow optical band gap (

We identified eight nonlinear crystals enabling THz emission from quadratic phase-matched Difference-Frequency-Generation: YCOB, BNA, LBO, CSP, AGS, CdSe, ZnO and GaP. For all these crystals, we performed Time-Domain Spectroscopy in the same conditions to determine their absorption spectra in polarized light as well as their principal refractive indices as a function of wavelength in the 0.5-2.0 THz range. By combining previous data with the Sellmeier equations valid in their visible and infrared transparency ranges, we calculated the coherence length of Difference-Frequency-Generation associated to all possible configurations of polarization and found interesting and complementary phase-matching conditions in the eight studied crystals.

Balancing the wide band gap, large second harmonic generation (SHG) response, and moderate birefringence are significant but addressable challenges for designing nonlinear optical (NLO) materials. Based on the band-gap engineering in perovskite solar cell materials, we have successfully synthesized a new fluorotellurite, BaF

Summary The biotrophic fungal pathogen Ustilaginoidea virens causes rice false smut, a newly emerging plant disease that has become epidemic worldwide in recent years. The U. virens genome encodes many putative effector proteins that, based on the study of other pathosystems, could play an essential role in fungal virulence. However, few studies have been reported on virulence functions of individual U. virens effectors. Here, we report our identification and characterization of the secreted cysteine‐rich protein SCRE1, which is an essential virulence effector in U. virens. When SCRE1 was heterologously expressed in Magnaporthe oryzae, the protein was secreted and translocated into plant cells during infection. SCRE1 suppresses the immunity‐associated hypersensitive response in the nonhost plant Nicotiana benthamiana. Induced expression of SCRE1 in rice also inhibits pattern‐triggered immunity and enhances disease susceptibility to rice bacterial and fungal pathogens. The immunosuppressive activity is localized to a small peptide region that contains an important ‘cysteine‐proline‐alanine‐arginine‐serine’ motif. Furthermore, the scre1 knockout mutant generated using the CRISPR/Cas9 system is attenuated in U. virens virulence to rice, which is greatly complemented by the full‐length SCRE1 gene. Collectively, this study indicates that the effector SCRE1 is able to inhibit host immunity and is required for full virulence of U. virens., The Ustilaginoidea virens effector SCRE1 can suppress plant immunity and promote disease development in rice and a novel small peptide region is identified to be essential for SCRE1 immunosuppressive ability.

Molecular sieves are of increasing importance in catalysis, the oil industry, and biomedicine. Traditional molecular sieves are generally oxides that inevitably show some absorption in the mid- and far-IR range due to the vibrations of metal-oxygen bonds, which are unfavorable for the in situ observation of the reactions in molecular sieves through IR techniques. In this study, a new metal halide In[Ba3Cl3F6] has been synthesized. It exhibits a quite transparent window from 0.366 to 22 μm and good adsorption and desorption processes.

Discovering new deep-ultraviolet (DUV) nonlinear optical (NLO) materials is currently a great challenge. The reported DUV NLO materials are almost exclusively borates or phosphates. Silicates-the largest constituent of the earth's crust-are excluded owing to their weak second harmonic generation (SHG) response. We report a silicate, Li2 BaSiO4 , with edge-sharing LiO4 -SiO4 tetrahedra that achieves the balance between a short UV absorption edge, below 190 nm, and a large SHG response, 2.8×KDP. The SHG intensity is the largest for silicates without second-order Jahn-Teller cations, and exceeds that of non-isomorphic Li2 SrSiO4 by more than an order of magnitude. As such Li2 BaSiO4 may be seen as a promising DUV-UV NLO material. This research indicates that edge-sharing tetrahedra is a new design parameter for discovering new DUV NLO materials.

Two-dimensional (2D) materials have exotic intrinsic electronic band structures and are considered as revolutionary foundations for novel nanodevices. Band engineering of 2D materials may pave a new avenue to overcome numerous challenges in modern technologies, such as room temperature (RT) photodetection of light with photon energy below their band gaps. Here, we reported the pioneering RT MoS

Using terahertz time-domain spectroscopy, we report the principal values of absorption coefficients and refractive indices as a function of wavelength between 0.5 and 2.0 THz of eight attractive nonlinear crystals: YCOB, BNA, LBO, CSP, AGS, CdSe, ZnO and GaP. From these data, we calculated the coherence length and phase-matching conditions associated to the emission of a THz wave from a second-order difference-frequency generation.

Optical parametric chirped-pulse amplification (OPCPA) can be used to generate ultrafast intense mid-IR lasers, however, the lack of suitable nonlinear optical crystals simultaneously having a wide transmission range, high laser damage threshold, and excellent phase-matching property hinders the development of mid-IR OPCPA. Here, we focus on the La3Nb0.5Ga5.5O14 (LGN) crystal and describe its growth, characterization, and application in mid-IR nonlinear frequency converters. We discuss the optimization of the starting polycrystalline component and temperature field aimed for the growth of large-size LGN crystals with a 60 mm diameter. We then present a detailed characterization of their optical properties, including transmission spectrum, refractive indices, and nonlinear coefficient. Our findings suggest the promising potential of LGN in generating both few-cycle pulses across 3 to 6 µm and terawatt-class OPCPA systems around 5 µm.

This work describes the different steps of the design of a cylindric Optical Parametric Oscillator. It is based on a BBO nonlinear crystal shaped as a partial cylinder to be pumped by a commercial micro-laser at 0.355 μm for an energetic and sub-nanosecond emission continuously tunable between 0.4 μm and 0.9 μm.

In this work, SrI2 and SrI2:Eu5% single crystals with size of O10 × 60 mm3 and O10 × 30 mm3 were successfully grown by edge-defined film-fed growth (EFG) method. In the crystal growth process, the crack and turbidity of the crystal were solved by designing a temperature field, thereby optimizing crystal quality and obtaining crack-free crystals. X-ray diffraction analysis was performed on the grown crystals, and the optical properties of these crystals have been investigated at room temperature. Under the excitation of ultraviolet (UV) light, the crystals exhibit a single luminescence peak centered at 435 nm (λex = 350 nm), and the photoluminescence (PL) decay time is 0.594 μs. In addition, the designed temperature field also provides a reference value for other crystals grown by EFG method.

Potassium tantalate niobate KTa1-xNbxO3 (KTN) single crystals with different x values (x = 0, 0.25, 0.37 and 0.45) were grown by a top-seeded growth solution method in a KTa1-xNbxO3 solid-solution system. The crystalline structure, optical and dielectric properties were investigated experimentally using X-ray diffraction, spectrophotometer and LCR meter, respectively. The compositions were measured by electron probe microanalysis. The band gap energy was calculated based on the optical transmittance spectra. The XRD results indicated that the single crystals exhibited cubic structure (x ≤ 0.37) and tetragonal phase (x = 0.45) at room temperature. The absorption properties demonstrated that the absorption coefficients and the band gap energy decreased with the increasing Nb component. The dielectric results indicated that the Curie point increased depending on the increasing Nb component.

A high quality Er 3+ /Yb 3+ :Lu 0.5 Gd 0.5 VO 4 crystal with dimensions of 20 × 24 × 28 mm 3 has been grown successfully by the Czochralski method. The concentrations of Er 3+ and Yb 3+ in the Er 3+ /Yb 3+ : Lu 0.5 Gd 0.5 VO 4 crystal were calculated to be about 0.95 mol% and 1.68 mol%, respectively. The XRD pattern of the crystal confirmed that it is isostructural with pure GdVO 4 and LuVO 4 single crystals. The thermal properties of the crystal were studied by analyzing specific heat, thermal expansion coefficients and thermal diffusivity. The spectroscopic characterizations of the crystal, including the polarized absorption spectra and fluorescence spectra were recorded at room temperature. Spectral parameters such as the intensity parameters ( Ω 2 , Ω 4 and Ω 6 ), oscillator strengths, radiative transition probability and radiative lifetime of Er 3+ were calculated by Judd-Ofelt theory. All the results suggest that Er 3+ /Yb 3+ : Lu 0.5 Gd 0.5 VO 4 crystals can be an excellent candidate laser material.

Pr3+-doped LaMgAl11O19 (LMA) crystals have been successfully grown by the Czochralski method with different concentrations ranging from 0.5 to 10.0 mol%. Crystalline quality and the phonon energy were determined by X-ray diffraction and Raman measurements. Spectroscopic parameters based on absorption spectra were systematically calculated using the modified Judd-Ofelt theory. The fluorescence results indicate a large dependence on the factor of doping concentration. The 3P0→3F2 transition red laser channel has the largest emission cross section at 10.7 × 10−20 cm2 for 5.0 mol% Pr:LMA. The fluorescence lifetime of the 3P0 energy level is determined to be 32.6 μs at room temperature with a quantum efficiency of 82.9% for a 5.0 mol% Pr3+-doped sample. The overall spectral properties confirm that Pr:LMA is a promising candidate for visible laser operation.

Summary Bowman–Birk trypsin inhibitors (BBIs) play important roles in animal and plant immunity, but how these protease inhibitors are involved in the immune system remains unclear. Here, we show that the rice (Oryza sativa) BBI protein APIP4 is a common target of a fungal effector and an NLR receptor for innate immunity. APIP4 exhibited trypsin inhibitor activity in vitro and in vivo. Knockout of APIP4 in rice enhanced susceptibility, and overexpression of APIP4 increased resistance to the fungal pathogen Magnaporthe oryzae. The M. oryzae effector AvrPiz‐t interacted with APIP4 and suppressed APIP4 trypsin inhibitor activity. By contrast, the rice NLR protein Piz‐t interacted with APIP4, enhancing APIP4 transcript and protein levels, and protease inhibitor activity. Our findings reveal a novel host defence mechanism in which a host protease inhibitor targeted by a fungal pathogen is protected by an NLR receptor.