5G NTN关键技术研究与演进展望

5G非地面网络（non-terrestrial network,NTN）技术是5G通信系统面向卫星通信和低空通信等新应用场景的重要技术，标志着5G技术应用从陆地通信走向了空间通信。首先分析了5G NTN和地面5G的差异点，包括网络架构、时频同步、HARQ和移动性管理等。进而介绍了3GPP Release 17的5G NTN标准进展及关键技术点与3GPP Release 18的5G NTN增强技术。最后展望了未来空、天、地一体化的技术演进。通过对5G NTN技术研究和标准分析，明确了5G和卫星通信融合的技术路线，并为后续6G空、天、地融合系统研究和设计提供基础。     

Enhancement in lithium storage performances of SiO2/graphene-based nanocomposites prepared by low cost and facile approach

Journal of Materials Science: Materials in Electronics - The new nanocomposites of silicon dioxide/reduced graphene oxide (SiO2/rGO) and silicon dioxide/nitrogen-doped reduced graphene oxide...     

Optical-luminescence properties of ZnO and TiO2 nanopowders obtained by pulsed laser reactive ablation

Journal of Materials Science: Materials in Electronics - The ZnO and TiO2 nanopowders have been prepared by means of the pulsed laser reactive ablation of metallic (Zn, Ti) targets. The Structural,...     

Dielectric performance and conductive mechanism of KNN-based ceramics prepared via sol–gel core–shell process

Journal of Materials Science: Materials in Electronics - 0.95(Li0.02Na0.50K0.48)(Nb0.95Sb0.05)O3–0.05AgTaO3@BaZrO3 (LNKNbSAT@BZ) lead-free ceramics were prepared via a sol–gel...     

Co?N graphene encapsulated cobalt catalyst for H2O2 decomposition under acidic conditions

Hydrogen peroxide (H₂O₂) has been listed as one of the 100 most important chemicals in the world. However, huge amount of residual H₂O₂ is hard to timely decomposed into O₂ and H₂O under acidic condition, easily resulting in explosion hazard. Here, we reported a core–shell structure catalyst, that is graphene with Co N structure encapsulated Co nanoparticles. Co N graphene shell serves as the active site for the H₂O₂ decomposition, and Co core further enhance this decomposition. Benefiting from it, the H₂O₂ decomposition were close to 100% after 6 cycles without pH adjustment, which increased 6 orders of magnitude compared with no catalyst. At the same time, the O₂ generation reached 99.67% in 2 h with little metal leaching, and ·OH has been greatly inhibited to only 0.08%. This work can cleanly remove H₂O₂ with little deep oxidation and protect the process of H₂O₂ utilization to achieve a safer world.     

双酚芴环氧树脂体系热性能和粘接性能研究

环氧树脂是一种性能优异的热固性树脂，在结构胶粘剂和纤维增强复合材料领域应用广泛。但是常见的环氧树脂体系耐热性普遍较差，近年来，航空航天领域对材料的热性能提出了更高的要求，常规的环氧树脂体系已经无法满足耐高温需求。针对该问题，我们设计了一种耐热性较高的双酚芴型环氧树脂体系，并对其热性能和粘接性能进行了研究。在本文中，首先采用流变学方法和DSC研究了其工艺性能，使用DMA和TGA法分析了环氧树脂体系的耐热性能，并通过单搭接剪切试验测试了该环氧体系的粘接性能。结果表明，双酚芴型环氧树脂体系可在180℃固化，固化后的玻璃化转变温度达到190℃，失重5%时的温度为392℃，150℃时的剪切强度为5.8 MPa，展现了优异的耐热性能和粘接性能。     

Annealing of Mineral-Like Host Matrices for High-Level Waste Immobilization

Inorganic Materials - We have studied the effect of annealing on the chemical and physical properties of mineral-like host matrices for immobilization of the rare-earth–actinide fraction from...     

Eco-friendly approach for preparation of hybrid silica aerogel via freeze drying method

Journal of Materials Science - In this paper, an eco-friendly method of producing hybrid silica aerogels by freeze-drying method (FD) is proposed. In the freeze-drying system, deionized water was...     

A medical Chatbot using machine learning and natural language understanding

Multimedia Tools and Applications - For people with busy schedules, travelling to and from a hospital for treatment is considerably time consuming, which leads them to ignore their health problems....