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Photonic devices based on ferroelectric domain engineering in thin film lithium niobate are key components for both classical and quantum information processing. Periodic poling of ridge waveguide can avoid the selective etching effect of lithium niobate, however, the fabrication of high-quality ferroelectric domain is still a challenge. In this work, we optimized the applied electric field distribution, and rectangular inverted domain structure was obtained in the ridge waveguide which is beneficial for efficient nonlinear frequency conversions. Second harmonic confocal microscope, piezoresponse force microscopy, and chemical selective etching were used to characterize the inverted domain in the ridge waveguide. In addition, the performance of nonlinear frequency conversion of the periodically poled nano-waveguide was investigated through second harmonic generation, and the normalized conversion efficiency was measured to be 1,720 % W−1 cm−2, which is close to 60 % that of the theoretical value. The fabrication technique described in this work will pave the way for the development of high-efficiency, low-loss lithium niobate nonlinear photonic devices.

Abstract The paleoenvironment of Jixian carbonate rocks in the Mesoproterozoic Ordos Basin is studied by carbon and oxygen isotope analyses, diagenetic environment analysis, and the restoration of paleosalinity and paleotemperature. The results indicate that the carbonate rocks of the Jixian System have always been in a near-surface environment and have not been deeply buried. The ranges of variation in δ13CPDB and δ18OPDB are relatively narrow, ranging from − 5.75 to 1.41‰ and − 8.88 to − 4.01‰, respectively, which is consistent with the stable tidal flat sedimentary environment during the Mesoproterozoic in the study area. The paleosalinity (Z) values range from 111.7 to 127.1, and the paleotemperature (T) values range from 32.7 to 57.33 °C, indicating a relatively warm paleoclimatic environment during the Mesoproterozoic era in the study area. The analysis shows that in a warm paleoclimatic environment, although carbon and oxygen isotopes, Z, and T have certain fluctuations, their ranges are relatively small, reflecting to some extent the stable tectonic environment of the study area during the Mesoproterozoic era. Comprehensive research shows that the Ordos Basin had a warm climate and a stable tectonic environment in the Mesoproterozoic, which may be a good response to the North China Block's position near the equator and continuous thermal subsidence in the Mesoproterozoic.

According to the bottle neck problem about low size precision and large wall thickness deviation of the single crystal turbine blade, considering the inaccuracy factors of boundary conditions during unidirectional solidification process, the contact element method was used to study the interaction between the blade and the shuttering. Meanwhile, the practice temperature field data,the finite element method with the coupled stress field and temperature field, were used to simulate the unidirectional solidification of the single crystal turbine blade. Based on the analysis result, the stress distributing and blade deformation were qualitatively discussed. The result indicates that the max-residual stress presents at the root air-inlets, and the max-residual stress of root air-inlets is 28.4% higher than that of blade-body. The dynamic change of the temperature and the stress can basically been reflected by the coupled temperature/stress method. It can provide references for modifying process for reducing the cast residual stress, improving dimensional accuracy and dimensional stability in the unidirectional solidification process.

As a kind of artificially structured media, electromagnetic metamaterials (MTMs) have exotic electromagnetic properties that are not found or difficult to achieve in natural materials. This class of metal/dielectric-structured artificial media has attracted great attention during the past two decades and made important breakthroughs. A variety of passive and active devices based on MTMs have been developed rapidly. Especially MTM klystrons, which show very remarkable advantages, including miniaturization, high gain, and high efficiency in the microwave band. MTM extended interaction klystrons creatively combine the advantages of MTMs, extended interaction technology, and klystrons. It provides a new design idea for the development of brand-new klystrons with high performance. In this review paper, we report the recent advances in MTM klystrons including MTM extended interaction oscillator and MTM extended interaction klystron amplifier. Furthermore, the prospects and challenges of MTM klystrons are discussed. Finally, the development trend is concluded.

A new tomato juice concentration technology was presented by CO2 hydrate formation. The CO2 hydrate equilibrium conditions were measured by isochoric pressure search method and tomato juice concentration experiments were carried out in a high-pressure stirred reactor. Moreover, dehydration ratio was defined and CO2 hydrate formation rate constants were calculated with different feed pressure. The effects of feed pressure, temperature, and juice volume on dehydration ratio were investigated. The results show that the tomato juice used in this work nearly has no effect on CO2 hydrate phase equilibrium conditions, but can accelerate CO2 hydrate formation. And the dehydration ratio increased with increasing the feed pressure from 1.81 to 3.95 MPa, the maximum dehydration ratio can reach 63.2% with feed pressure of 3.95 MPa, and the optimum tomato juice volume is 80 mL. These results demonstrated that removal of water with the help of CO2 hydrate is an efficient technology for tomato juice concentration.

Glutamate intercalated Mg–Al layered double hydroxide (LDH) was prepared by co-precipitation and the removal of Pb2+ in the aqueous solution was investigated. The prepared samples were characterized by XRD, FT-IR and SEM. It was shown that glutamate can intercalate into the interlayer space of Mg–Al LDH. The glutamate intercalated Mg–Al LDH can effectively adsorb Pb2+ in the aqueous solution with an adsorption capacity of 68.49 mg g−1. The adsorption of Pb2+ on glutamate intercalated Mg–Al LDH fitted the pseudo-second-order kinetics model and the isotherm can be well defined by Langmuir model.

Based on a great number of laboratory experiments, a new technique has been developed for producing wear resistant ring-hammers. In this technology, lost foam casting with iron sand was combined to make mold; a special alloy was used to inoculate the molten steel, and proper heat treatment was used to further improve mechanical properties of wear resistant ring-hammers. The influence of this new production technology on the microstructure and mechanical properties of wear resistant ring-hammers was studied. Results show that iron sand molding, having the inherent characteristic of sand molding, changes the type of metallic compounds, refines crystal grains and increases the fineness of microstructure. Practical experience verified that the properties of the ring-hammers produced with this new technique are as follows: tensile strength (Rm) 720 MPa, impact toughness (ak) > 210 J•cm-2 and hardness > 200 HB. After water quenching from 1,080℃ (holding for 4 h) and tempering at 320℃ for 3 h, the best wear resistance is obtained, and the wear resistance is 1.6 times higher than that of common high manganese ring-hammers.

Author(s): Shifeng Li [sup.1] [sup.2] , Yingchun Xia [sup.1] [sup.2] , Wei Zhao [sup.1] [sup.2] , Xiaohui Miao [sup.1] [sup.2] , Qiongying Xu [sup.1] [sup.2] Author Affiliations: (1) grid.412260.3, 0000 [...], Previous studies have shown that self-affirmation increases acceptance of a message and motivates health behavior change. The present study investigated whether self-affirmation increases the acceptance of persuasive messages on COVID-19 vaccines and promotes vaccination intention. A total of 144 participants were randomly assigned to the self-affirmation (n = 72) or control (n = 72) groups before reading a persuasive message on COVID-19 vaccines. The results revealed that the self-affirmation group showed significantly higher acceptance of persuasive information on COVID-19 vaccines than the control group. Additionally, the self-affirmation group also showed significantly higher post-experiment vaccination intention than the control group. Mediation analysis indicated that increased acceptance of persuasive information significantly mediated the beneficial effects of self-affirmation on post-experiment vaccination intention. The present study demonstrated that self-affirmation could be an effective strategy for increasing the acceptance of persuasive messages on COVID-19 vaccines and promoting vaccination intention.