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The bonding performance of CFRP-steel joints between carbon fiber reinforced polymer （CFRP） plate and steel is seriously affected by marine environment. In order to evaluate the bonding strength of CFRP-steel joints exposed to marine environment， a double-lap shear joint on five specinmens with different bonding lengths were corroded for 7 to 21 days in the NaCl solution. The technique of digital image correlation （DIC） was applied to measure the normal strain distribution on the surface of CFRP. Scanning electron microscope （SEM） and energy dispersive spectrometer （EDS） were used to observe microscopic information and monitor element content changes of CFRP surface. The results show that the contents of Na+ and Cl- on the CFRP surface are increased with the increase of corrosion period， which induces charge compensation. Electrolyte penetration into the interface leads to free volume expansion， resulting in a decrease in the interfacial binding strength. The adhesion failure at the interface of adhesive and CFRP is observed in the experiment. The corrosion is aggravated with the increase of time， leading to the decrease of the ultimate load and the ductility. The interface ductility decreases after corroding for 7 to 14 days and the strain softening disappears and exhibits characteristics of the brittle failure after corroding for 21 days. The finite element model was established based on the Fickian theory and bonding-slip constitutive parameters.The diffusion characteristics of seawater between bonding interfaces and the interface typeⅡ delamination process were simulated，and the numenical results are in good agreement with the expermental results.

Propeller propulsion technology plays an important role in aviation field. Composite materials have the characteristics of high specific strength，high specific modulus，high damping，designability and so on. The use of composite material propeller blades can further improve the performance of propeller in terms of mass reduction efficiency，propulsion efficiency，corrosion resistance，noise reduction. Composite material propeller blades have become the general trend. Based on aircraft propeller blades and rotor blades，this paper aims to perform a brief review of the research achievements of aviation composite propeller blades at home and abroad，classifies and expounds the material systems，structural design and molding processes of aviation propellers. The key technical problems and the simulation research on manufacturing process of propeller at home and abroad are summarized. Finally，the future development direction of domestic composite propellers from the aspects of improving the material system，optimizing the structure design，deepening the process research and strengthening the engineering application of numerical simulation technology are concluded.

Type I collagen carboxyl-terminal peptide β (β-CTX) increases in osteoporosis. The study aimed to explore the relationship between serum β-CTX and the risk of osteoporosis as well as sarcopenia in Chinese elderly inpatients. Around 228 patients whose age >65 years were recruited in this cross-sectional study. Dual-energy X-ray scanning was used to access skeletal muscle and bone mass. Serum concentration of β-CTX as well as the prevalence of osteoporosis were significantly higher in low skeletal muscle index (SMI) group than that in the normal SMI group (P < 0.05). Serum β-CTX levels negatively correlated with SMI and bone mass (P < 0.05). Total muscle mass, appendicular skeletal muscle mass, SMI, total bone mass, and bone mass at various sites including the limbs, spine, and pelvis decreased significantly, and the prevalence of low SMI increased with the increase of the quartiles of β-CTX. Higher serum β-CTX had an increased risk of low SMI and osteoporosis (P < 0.05). Summarily, with increasing serum β-CTX levels, both muscle and bone mass decreased in Chinese elderly inpatients. Serum β-CTX was positively associated with the risk of not only osteoporosis but also skeletal muscle loss.

Economic globalization and regional integration are the core motivations of regional cooperation in the 21st century, and the issue of cross-border cooperation has attracted much academic attention. As the largest regional integration organization with the highest level in the world, EU takes the lead in practicing regional integration in the process of economic globalization. Europe's cross-border governance has been paid attention in a long time in economic geography and political geography, and a large number of theoretical and empirical research results have been achieved on issues such as border cooperation model and cross-border governance mechanism. The development experience of EU provides rich theoretical and practical experience for the collaborative governance in the Guangdong-Hong Kong-Macao Greater Bay Area, as the two also involve the collaboration across institutional boundaries and power restructuring. Therefore, the analysis of EU cross-border cooperation is of great significance to promote Guangdong-Hong Kong-Macao coordination. Based on the bibliometric analysis of Citespace, this paper systematically studies the research trends of EU cross-border cooperation from 1993 to 2020. The study finds that: 1) EU cross-border cooperation research mainly focuses on border regional interaction, cross-border cooperation mode, cross-border cooperation field, cross-border cooperation barriers and other issues. The regional integration of Europe has promoted the transformation of border areas from marginal areas to the forefront of development, and gradually formed a cross-border governance model under the superposition of formal institutional arrangements and informal institutional arrangements. The field of cooperation involves economic cooperation, tourism, environmental governance, health and other fields. 2) The development of EU cross-border cooperation benefits from the political interaction and mutual trust between countries, formal and informal institutional coordination, and the expansion and deepening of the scope of cooperation. However, there are still deficiencies in bilateral differences, cross-border accessibility, immigration and security. 3) As the same cross-institutional border region, the practical experience of EU cross-border cooperation has important enlightenment for the collaborative governance in the Guangdong-Hong Kong-Macao Greater Bay Area. Value identity is the basis of cross-institutional cooperation in the Guangdong-Hong Kong-Macao Greater Bay Area. Inclusive and orderly institutional arrangements are conducive to reducing the shielding effect of cooperation boundaries. And the combination of multi-scale cooperation and multi-dimensional governance system will effectively improve the cooperation in border areas.