共焦回旋行波管注波互作用研究

共焦回旋行波管是一种采用新型高频结构的回旋器件,它能够工作在相对较高的工作模式,共焦波导通过衍射损耗抑制低阶模式,实现其模式选择特性。与此同时,由于共焦波导场分布的特点,采用共焦波导作为高频结构的回旋行波管的效率会有所降低。本文旨在研究共焦回旋行波管的注波互作用特点,针对共焦波导场分布的特性,在理论上采用特殊的电子注以提高其互作用效率。     

混氢对汽油机循环变动及稀燃极限的影响

为了更好地了解掺入氢气对乙醇燃烧时的作用机理,利用CHEMKIN PRO程序,对稀燃工况下的乙醇/氢气预混层流燃烧进行了化学反应动力学分析,采用一种辨识方法,对不同掺氢体积分数下,掺氢对乙醇燃烧的主要产物和中间产物的化学作用及热/稀释作用进行了区分、研究和讨论.结果表明：氢气的化学作用会促进乙醇消耗和中间组分的生成,并使其反应摩尔分数分布曲线向反应上游移动,增加反应速率;而热/稀释作用会抑制组分的生成,使反应摩尔分数分布曲线向下游移动,减缓反应速率;综合作用会使掺氢后的化学反应提前发生,并对有害污染物甲醛的产生起到抑制作用.

     

Enhanced Photocatalytic Activity of Lead-Free Cs2TeBr6/g-C3N4 Heterojunction Photocatalyst and Its Mechanism

In this study, a new type of lead-free double perovskite Cs₂TeBr₆ combined with metal-free semiconductor g-C₃N₄ heterojunction is constructed and used for photocatalytic CO₂ reduction for the first time. The S-scheme charge transfer mechanism between Cs₂TeBr₆ and g-C₃N₄ is systematically verified by X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR) and in situ Fourier infrared spectroscopy(FT-IR). The formation of S-type heterojunction makes the photocatalyst have higher charge separation ability and highest redox ability. The results show that 5%-CTB/CN heterojunction material has the best photocatalytic reduction effect on CO₂ under visible light irradiation. After 3 h of illumination, the yield of CO and CH₄ are 468.9 µmol g⁻¹ and 61.31 µmol g⁻¹, respectively. The yield of CO is 1.5 times and 32 times that of pure Cs₂TeBr₆ and g-C₃N₄, and the yield of CH₄ is doubled compared with pure Cs₂TeBr₆. However, g-C₃N₄ almost does not produce CH₄, which indicates that the construction of heterojunction helps to further improve the photocatalytic performance of the material. This study provides a new idea for the preparation of Cs₂TeBr₆/g-C₃N₄ heterojunction and its effective interfacial charge separation.     

Anti-Swelling,High-Strength,Anisotropic Conductive Hydrogel with Excellent Biocompatibility for Implantable Electronic Tendon

As hydrogels rapidly advance for diverse technologies, their practical applications as implantable artificial tendon becomes promising, yet challenging. It requires similar anisotropic fibril structures, matching water content, high mechanical strength, good biocompatibility, and stable performance under physiological conditions. Furthermore, the capabilities of real-time joint motion monitoring and implant condition are extremely important for the precise assessment of rehabilitation processes. However, it is challenging to realize all these properties simultaneously. Herein, this work reports an intelligent implantable artificial tendon based on strong and conductive anisotropic hydrogel, by coupling prestretching-induced ordered structure with drying-enabled strengthening. The fiber structure fixed during drying/rehydration produces a dense and stable network with a hierarchically anisotropic structure. The resulting anisotropic hydrogel presents excellent anti-swelling ability (<3%), high tensile strength (3.71 MPa), and toughness (9.86 MJ m⁻³) upon hydration, at a tendon-matching water content of 72.5 wt%. The in vitro and in vivo tests demonstrate its excellent biocompatibility with significant protein resistance. With reliable strain sensing, the hydrogel can act as an intelligent artificial tendon to restore and real-time monitor joint motion in an in vitro model. The SD rats with tendon defects display restored motor function after implantation of the hydrogel as tendon substitutes, facilitating malfunction tissue therapeutics and rehabilitation.     

Nanoengineering Calcium Peroxide-Based Site-Specific Delivery Platform to Efficiently Activate the cGAS-STING Pathway for Cancer Immunotherapy by Amplified Endoplasmic Reticulum Stress

Currently, the understanding of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway's involvement in efficient immunotherapy mainly revolves around the role of mitochondria or nucleus modulation. Nonetheless, the role of endoplasmic reticulum (ER) stress in activating the cGAS-STING mechanism to boost immunity against tumors remains essentially unexplored. Herein, novel findings demonstrating that ER stress can be used as a strategy for stimulating the cGAS-STING pathway, thereby augmenting the immune response against cancer, are presented. To accomplish this objective, ER-targeting p-methylbenzene sulfonamide-tailored IR780 (p-780) is synthesized and it is loaded into CaO₂ nanoparticles, which are further functionalized with distearoyl phosphoethanolamine-polyethylene glycol（DSPE-PEG）-biotin to form PEG/CaO₂@p-780 NPs. The disruption of calcium homeostasis, coupled with the heightened levels of reactive oxygen species (ROS) mediated by p-780, along with hyperpyrexia, collectively contributes to the amplification of endoplasmic reticulum (ER) stress. This cascade of events effectively triggers the cGAS-STING pathway and, in parallel, facilitates the degradation of the programmed cell death 1 ligand 1 (PD-L1) protein. In addition, oxygen released through CaO₂ decomposition is expected to promote p-780–mediated phototherapy, while reversing the immunosuppressive tumor microenvironment associated with hypoxia. Furthermore, DSPE-PEG-biotin facilitates tumor site-specific drug delivery through active targeting mediated by the biotin receptor. Collectively, PEG/CaO₂@p-780 nanoparticles successfully activate systemic antitumor immunity by enhancing ER stress.     

Two-dimensional ferromagnetic materials and related van der Waals heterostructures: a first-principle study

Since the successful fabrication of two-dimensional (2D) ferromagnetic (FM) monolayer CrI₃ and Cr₂Ge₂Te₆, 2D FM materials are becoming an exciting research topic in condensed matter physics and materials fields, as they provide a good platform to explore the fundamental physical properties of magnetic materials under 2D limit. In this review, we summarize the theoretical research progress of intrinsic 2D FM materials and related van der Waals heterostructures (vdWHs) including their electronic structures, magnetism, Curie temperature, valley polarization, and band alignment. Moreover, we also summarize recent researches on the methods that used to regulate the above properties of 2D FM materials and vdWHs, such as defects, doping, strain, electric field and interlayer coupling. These studies show that 2D FM materials have broad application prospects in spintronics and valleytronics. However, there are still many problems waiting to be solved on the way to practical application.     

基于自适应调制技术的MIMO UWB无线通信系统的研究

在对多输入多输出(MIMO)技术和超宽带(UWB)无线通信研究的基础上提出了一种基于自适应调制技术的时变多进制MIMO UWB系统。通过采用奇异值分解理论和速率分阶的方法对系统性能进行了分析,推导出了速率离散分阶情况下的功率和速率的分配公式,提出了相邻时隙平均功率控制(JTAPC)算法,并且对系统的性能进行了仿真。研究结果表明,功率控制算法的使用很大程度上提高了采用速率分阶的系统的性能,并且降低了系统实现的复杂度。     

基于基库的多实化视图增量维护算法

基于基库的多实化视图维护将基库集作为多个实化视图的辅助视图集保存在集成端。当信息源发生变化时,基库随着更新,同时触发多实化视图的更新与维护。在保存基库的情况下,多实化视图的维护无需访问信息源就可完成,是多实化视图的自维护方式。     

Biomimetic Modification of Water-Borne Polymer Coating with Carnauba Wax for Controlled Release of Urea

Benefitting from the special structure of the leaf cuticle layer, plants have natural hydrophobicity and anti-fouling abilities. Inspired by the leaf surface structure, a biomimetic modification strategy was raised to improve the surface hydrophobicity of polyacrylate coating for controlled release fertilizer. Double-layer (polyacrylate and carnauba wax) coated fertilizer was obtained after biomimetic modification. The quality of controlled release fertilizer modified with the carnauba wax was greatly enhanced, and the coating material was effectively saved. The surface appearance of polyacrylate-coated fertilizer was improved for the surface blemish was repaired by the loaded carnauba wax. The characterizations by Fourier transform infrared spectroscopy indicated that the hydrogen bonds were formed between the water-based polyacrylate membrane and the carnauba wax layers. By optimizing the content of polyacrylate and carnauba wax, the release duration of the fertilizer was effectively prolonged, which was improved from 1 month to more than 2 months after the biomimetic modification. Therefore, biological wax as an environmentally-friendly natural material that has showed a broad potential in the application of coated controlled release fertilizer.