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Article  |  2021-11-30

Preparation and Characterization of High-Strength Geopolymer Based on BH-1 Lunar Soil Simulant with Low Alkali Content

The construction of a lunar base and habitation on the Moon has always been on researchers’ minds. Building materials used in in situ lunar resources are of great significance for saving expensive space freight. In this study, a new type of lunar soil simulant named Beihang (BH)-1 was developed. The chemical mineral composition and microstructure of BH-1 closely resemble those of real lunar soil, as verified by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and reflectance spectra. This research also synthesized a geopolymer based on BH-1 cured at simulated lunar atmospheric conditions. We also investigated the effect of supplementing aluminum (Al) sources on the enhancement of geopolymer strength based on BH-1. The rheological behavior of alkali-activated BH-1 pastes was determined for workability. XRF, XRD, Fourier transform infrared spectroscopy, SEM coupled with energy dispersive spectroscopy, and 27Al magic angle spinning-nuclear magnetic resonance were used to characterize resulting geopolymers. Rheological test findings showed that the rheology of BH-1 pastes fits the Herschel–Bulkley model, and they behaved like a shear-thinning fluid. The results showed that the 28-day compressive strength of the BH-1 geopolymer was improved by up to 100.8%. Meanwhile, the weight of additives required to produce per unit strength decreased, significantly reducing the mass of materials transported from the Earth for the construction of lunar infrastructure and saving space transportation costs. Microscopic analyses showed that the mechanism to improve the mechanical properties of the BH-1 geopolymer by adding an additional Al source enhances the replacement of silicon atoms by Al atoms in the silicon–oxygen group and generates a more complete and dense amorphous gel structure.

Siqi Zhou ,   Chenghong Lu   et al.

Article  |  2021-11-30

Mars Helicopter Exceeds Expectations

Mitch Leslie  

Article  |  2021-11-26

Development Strategy of the New-Generation Effectiveness-Oriented Earth-Observation System

China has established three series of remote sensing satellite systems for land, ocean, and atmosphere through the establishment of a high-resolution Earth observation system and the implementation of national civil space infrastructure planning. However, the current systems in China neglect data application and data services while emphasizing satellite engineering. Considering the future requirements of Earth observation for high quality, high benefit, and high efficiency, we adopt an effectiveness analysis method to study the Earth observation systems. We clarify the global development trends of Earth observation satellite systems and summarize the current status in China. Based on this, we analyze the demand and challenges for an effectiveness-oriented Earth-observation system and propose the development goals, components, and key tasks of the new-generation Earth-observation system that features system effectiveness. To improve the application service system and capabilities of China’s remote sensing satellites and to transform the orientation from business services to system effectiveness, it is necessary to build a space–ground integrated perception backbone network as well as management and data transmission tool networks based on top-level design with the High Resolution Earth Eye Program as the core, and implement major application demonstration projects. Moreover, national spectral data sources, quantitative application databases, and industrial ecology cloud platforms need to be strengthened, thereby transforming satellite engineering toward satellite application engineering and constructing a complete national civil space infrastructure.

Zhao Wenbo ,   Li Shuai   et al.

Article  |  2021-11-22

Strategic Planning of Global Innovation and Industry Highland in Guangdong–Hong Kong–Macao Greater Bay Area from a Medium- and Long-Term Perspective

As the construction of Guangdong–Hong Kong–Macao Greater Bay Area enters a new stage, it is necessary to further improve technological innovation and emerging industries of this area and promote its global influence to support the high-quality development of China’s industries. In this study, we analyze the role of this area in the national economic development and explore the development status of technological innovation and emerging industries in this area. Moreover, we propose strategic goals and key tasks for the medium- and long-term development under the unique institutional framework of “one country, two systems”. The Guangdong–Hong Kong–Macao Greater Bay Area can be built to be a global innovation and industry highland that is open, integrated, and sustainable via four steps by 2050, and a borderless Greater Bay Area can be constructed orderly through integrated technological innovation. The key tasks that we proposed include: (1) strengthening the construction of an international technological innovation center, (2) improving the ability of science and technology to support industrial development, (3) cultivating world-class clusters of emerging industries, (4) creating a gathering place for outstanding professionals in China and abroad, (5) deepening the integration of finance and technology, (6) establishing a diversified investment coordination mechanism for scientific innovation, and (7) exploring an innovation and industrial factor flow mechanism.

Wang Yingjun ,   Zeng Zhimin   et al.

Article  |  2021-11-22

Building a New Electric Power System Based on New Energy Sources

Building a new electric power system that is based on new energy sources is an important direction for power system transformation and upgrading in China, and it is critical for peaking carbon emissions and achieving carbon neutrality. In this study, we analyze the changes and challenges that are brought by power system transformation and elaborate on the connotation and building principles of a new electric power system. Moreover, we categorize the development of the new system into stages and propose development suggestions for each stage considering the technical features of the system and the new energy access scale. The new electric power system proposed in this study can satisfy the increasing demand for clean power as it primarily uses new energy sources and it has the features of high safety, openness, and adaptability. Building the new electric power system should follow the technical evolution law and characteristics of power systems; it should further exploit the potentials of mature technologies and current power systems. Meanwhile, emerging technologies should be researched and developed.

Shu Yinbiao ,   Chen Guoping   et al.

Article  |  2021-11-19

Surface-tailoring chlorine resistant materials and strategies for polyamide thin film composite reverse osmosis membranes

Polyamide thin film composite membranes have dominated current reverse osmosis market on account of their excellent separation performances compared to the integrally skinned counterparts. Despite their very promising separation performance, chlorine-induced degradation resulted from the susceptibility of polyamide toward chlorine attack has been regarded as the Achilles’s heel of polyamide thin film composite. The free chlorine species present during chlorine treatment can impair membrane performance through chlorination and depolymerization of the polyamide selective layer. From material point of view, a chemically stable membrane is crucial for the sustainable application of membrane separation process as it warrants a longer membrane lifespan and reduces the cost involved in membrane replacement. Various strategies, particularly those involved membrane material optimization and surface modifications, have been established to address this issue. This review discusses membrane degradation by free chlorine attack and its correlation with the surface chemistry of polyamide. The advancement in the development of chlorine resistant polyamide thin film composite membranes is reviewed based on the state-of-the-art surface modifications and tailoring approaches which include the in situ and post-fabrication membrane modifications using a broad range of functional materials. The challenges and future directions in this field are also highlighted.

 

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