The use of multi-perspective and multi-scalar city networks has gradually developed into a range of critical approaches to understand spatial interactions and linkages. In particular, road linkages represent key characteristics of spatial dependence and distance decay, and are of great significance in depicting spatial relationships at the regional scale. Therefore, based on highway passenger flow data between prefecture-level administrative units, this paper attempted to identify the functional structures and regional impacts of city networks in China, and to further explore the spatial organization patterns of the existing functional regions, aiming to deepen our understanding of city network structures and to provide new cognitive perspectives for ongoing research. The research results lead to four key conclusions. First, city networks that are based on highway flows exhibit strong spatial dependence and hierarchical characteristics, to a large extent spatially coupled with the distributions of major megaregions in China. These phenomena are a reflection of spatial relationships at regional scales as well as core-periphery structure. Second, 19 communities that belong to an important type of spatial configuration are identified through community detection algorithm, and we suggest they are correspondingly urban economic regions within urban China. Their spatial metaphors include the administrative region economy, spatial spillover effects of megaregions, and core-periphery structure. Third, each community possesses a specific city network system and exhibits strong spatial dependence and various spatial organization patterns. Regional patterns have emerged as the result of multi-level, dynamic, and networked characteristics. Fourth, adopting a morphology-based perspective, the regional city network systems can be basically divided into monocentric, dual-nuclei, polycentric, and low-level equilibration spatial structures, while most are developing monocentrically.

Trade facilitation is one of the five main agendas of the Belt and Road Initiative (BRI). Social network analysis has helped understand the complexity of trade networks, but existing studies tend to overlook the fact that not all bilateral trade relations are equally important to a country. To fill this gap in the literature, this paper focuses on the top 2 trade relations networks to illuminate the structure and evolution of B&R trade relations, the relative positions of different countries, and changes in the composition of trade communities (e.g., the community leaders) and the changing patterns of trade between them. We find rich dynamics over time both inter-and intra-communities. The overall international trade networks of B&R countries experienced a leadership change from Russia to China on one hand, some temporary communities experienced emergence, disappearance (e.g. the Kuwait-and Thailand-led communities) or reemergence (e.g. Poland-led community), and a community membership was generally consistent on the other hand. Since the future impacts of China's BRI will depend on the degree of integration of the connected regions, some countries with stable and high centrality indices (e.g. Russia,

An energy-efficient method has been developed to prepare 3-5 nm-wide carboxyl-functionalized cellulose nanofibers (CNFs) from pulp fiber by a simple one-pot swelling followed by esterification process. Tetrabutylammonium acetate (TBAA)/dimethyl sulfoxide (DMSO) binary solvent is used as the swelling agent and the esterification medium admixed with maleic anhydride. All steps are performed at room temperature and no post-mechanical treatment is needed. The highly efficient defibrillation of pulp fiber to CNFs is thought to be due to two factors: 1) swelling in TBAA/DMSO effectively loosens the structure of cellulose supermolecules by breaking the intra- and intermolecular hydrogen bonds between cellulose chains; and 2) the carboxyl groups grafted onto the cellulose molecules by esterification prohibit the reformulation of hydrogen bonds between cellulose chains and therefore stabilize the disperse CNFs with uniform diameter in solution. Other than acid anhydride, no catalyst is added for the esterification, which facilitates the recycling and reuse of the binary solvent. This energy-efficient one-pot method could facilitate the large-scale manufacture of bio-based nanomaterials.

At present, cellulose nanocrystal (CNC) aerogels with high adsorption properties for CO 2 are mostly prepared by the liquid phase method which leads to the problem of modifier loss. In this work, a novel amino CNC aerogel was developed by chemical vapor deposition using 3-(2-aminoethylamino)-propylmethyldimethoxy silane (APS) as the modifier, which improved the utilization ratio of the modifier while ensuring the CO 2 adsorption performance. Herein, the as-prepared APS− CNC aerogel was characterized with elemental and functional groups and thermal, morphological, and structural characteristics by various measurements (X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and Brunauer−Emmet− Teller equation). It exhibited a porous network structure with low specific surface area (29.14 m 2 /g) and excellent thermal stability. Furthermore, the CO 2 adsorption capacity of the CNC aerogel grafted with APS reached 1.5034 mmol/g (25 °C, 1 bar, and pure dry CO 2 atmosphere). Meanwhile, the APS−CNC aerogel showed excellent CO 2 adsorption/desorption recyclability after 10 cycles. The experimental results showed that the CNC aerogel modified by chemical vapor deposition had an important potential role as a biomass CO 2 solid adsorbent.

Cereal trade is essential for economic and commercial cooperation among countries along the “Belt and Road” (BRI). It helps ensure food security and contributes to building a community of interests and destinies for the BRI countries. Based on the UN Comtrade database, this study, using a network analysis approach, investigates the structural characteristics and spatiotemporal dynamics of cereal trade networks among the “Belt and Road” countries. Results show that: (1) The cereal trade among the BRI countries has formed well-connected and complex trade networks, and the “Belt and Road” initiative has significantly promoted cereal trade networks among the BRI countries. (2) The backbone structures of cereal trade networks along the BRI are in geographical proximity. India, Russia, and Ukraine are the most important trading partners and absolute core nodes in the trade networks, influencing the entire cereal trade networks. (3) The BRI cereal trade networks exhibit significant core-periphery structures, with considerable power asymmetries between the countries reflecting food supply and demand differences. In general, the BRI cereal trade networks have developed from relatively diversified to polarized. Supply chains in the cereal trade network are dominated by a few large countries and are fragile, with weak resilience and low resistance to risk. Therefore, governments should continue to strengthen regional cooperation, optimize cereal trade network structure, enhance their reserve capacity, and build a stronger system to guarantee food security and prevent risk. All these measures will support the food security of the “Belt and Road” countries.

The formaldehyde‐free resin impregnated paper is expected to be applied to interior decoration materials and furniture. This is not only conducive to the development of indoor environment toward green and environmental protection, but also beneficial to people's health. In this work, the formaldehyde‐free resin (waterborne polyurethane and waterborne acrylic acid) mixed with cellulose nanocrystal (CNC) were separately coated on a raw decorative paper by a dipping method to obtain formaldehyde‐free impregnated paper with outstanding surface bound strength and abrasion resistance. The surface bound strength and abrasion resistance were tested by means of universal ability test machine and abrasion tester. The results showed that waterborne polyurethane and waterborne acrylic acid enhanced by CNC had excellent dispersion, and the bonding properties of formaldehyde‐free impregnated paper were improved by 41.3 and 33.3%, respectively. Meanwhile, the abrasion resistance of formaldehyde‐free impregnated paper was improved by the crystal effect of CNC. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48931.

Although there is a need to determine the spatial accessibility of cities in China, the limitations in available data and methods hinder research in this area. The main objective of this study was to quantify the accessibility of cities in China. We developed a comprehensive analytical method to quantify spatial accessibility at a spatial resolution of one kilometer by integrating both land surface conditions and transport networks. The results show that the spatial patterns of accessibility of Chinese cities at the prefecture level and above are characterized by significant spatial heterogeneity, consistent with the patterns in physical geography, population density, and economic activities. The results improve our understanding of deficiencies in the accessibility of cities in China and provide a foundation for transportation infrastructure planning.

The idea of megaregions, which focuses on polycentricity, competitiveness, and integration attracts much attention in research and policy. China has used megaregions as a normative governance framework that leverages polycentric regional development for balancing economic competitiveness and spatial development. This paper explores to what extent these megaregions actually reveal polycentric versus monocentric structures. The analysis demonstrates a divergence between the morphological and functional organization of China’s megaregions. Five types of megaregions are identified as per the relationships between the morphological and functional dimensions. Functionally, the Pearl River Delta, Shandong Peninsula, and Yangtze River Delta are among the most polycentric megaregions. The majority of others, even where morphologically polycentric, do not exhibit high degrees of functional polycentricity. The study demonstrates a problematic nature of megaregions as a governance agenda for regional polycentricity. It argues that if China genuinely wants to achieve greater levels of polycentricity and spatial cohesion, differentiated policies should be implemented for megaregions.