Building Warships and Nurturing Technical Talent at the Foochow Navy Yard during the Self-Strengthening Movement

In 1866, after the Opium Wars, the Chinese official Zuo Zongtang established the Foochow Navy Yard, which aimed to facilitate the independent construction of modern warships. French advisers, engineers, teachers, and craftsmen were hired, and a series of French schools for naval construction, drawing, and apprenticeship were set up. Previous studies have nearly exhausted the historical material on the Foochow Navy Yard, but few of them give an exact evaluation on its shipbuilding and educational levels. This paper traces the French sources on the shipbuilding technology and educational system at the Foochow Navy Yard and conducts a comparative study. With the guidance and assistance of foreigners, the Foochow Navy Yard gained the ability to assemble ships and imitate engines, while it remained necessary to import design drawings and structural components. The most outstanding students that the navy yard nurtured may have reached the level of école Polytechnique graduates, but the quality of students was hard to maintain. The backwardness of its conceptualization and the lack of financial and political support also contributed to its decline.

Diselenide as a Dual Functional Mechanophore Capable of Stress Self-Reporting and Self-Strengthening in Polyurethane Elastomers

Unlike biological materials that can sense mechanical force and actively remodel locally,synthetic polymers typically break down under stress.Molecular-level responses to damage with both stress-reporting and self-strengthening functions are significant yet difficult to realize for synthetic polymers.To overcome this challenge,chemo-mechanical coupling into polymers that can simultaneously ameliorate mechanical,optical,or other functional properties of a polymer combined with mechanical treatment will offer a new principle for materials design.Here,we report a kind of elastomer in which destructive forces are channelled into productive and bond-forming reactions by using diselenide(Se–Se)as a mechanophore.Polyurethane has been functionalized with labile Se–Se bonds,whosemechanical activation generates seleno radicals that trigger radical transfer and cross-linking reactions in situ.These reactions are activated efficiently in a mechanical way by compression in bulk materials.The resulting covalent networks possess turn-on mechano-fluorescence and increased moduli,which provide the functions of stress reporting,mechano-healing,and mechano-remodeling for the deformed film.This study not only illuminates themechano-responsive nature of Se–Se bonds in the bulk state but also paves the way for the development of new stress-responsive materials.

The self-strengthening mechanism in the development of a resource-based economy： with a case study

A resource-based economy is an economic system driven by the exploitation of mineral resources and dominated by the energy, mineral and other resource sectors. In resource- rich areas, there is often an investment bias toward the resource sector because of the existence of a threshold for investment in human capital in the manufacturing sector. Once the resource sector is dominant, it has a particular atwaction effect on the economic factors; its expansion and spread have a viscosity effect on industry families;, and the sunk costs and path dependence that emerge as industrialization evolves have a lock-in effect on the role of resources. This may give rise to development path dependence and the trap of resource advantage, resulting in a self-strengthening mechanism in resource-based economies. The key to escaping this trap is to break down the resource sector＇s original self-perpetuating mechanism and path dependence, introduce learning and innovation, adjust mechanisms far the distribution of resource benefits and realize industry coordination and transformational economic development.

Returned Diplomats,French Engineers,and the Qingxi Ironworks:Self-Strengthening and Self-Representation in the Late Qing

This article explores the history of the Qingxi Ironworks in late Qing Guizhou.Instead of focusing on state-centered industrialization or technology transfer and scientific knowledge in Qing mining and coal enterprises,this study focuses on the individual ambitions and identity construction of two returned diplomats——Chen Jitong and Chen Mingyuan—who sought to claim authority over a mining interest in China's southwest interior.By leveraging their knowledge of the West to serve as intermediaries between state and foreign commercial interests,these cosmopolitan yet marginalized elites sought to convert their foreign expertise and avowed commitment to "selCstrengthening" into new forms of social and political capital.An examination of the personal networks and written accounts surrounding their entrepreneurial ventures sheds light on the opportunities and challenges experienced by a generation of "foreign affkirs" experts in repositioning themselves within the transforming Qing polity through participation in industrialization projects.

A Self-Strengthening Epidermis-Like Smart Coating Enabled by Dynamic Iron Sequestration

Living organisms rely on materials sequestration from the environment to strengthen their bodies.Such constant activity provides necessary supplies for critical biological functions,which is difficult by man-made structures due to the lack of a dynamic sequestration mechanism.In this study,it is shown that an epidermis-like smart coating can respond to changes in salinity to allow a spontaneous and progressive strengthening when supported by steel as a sustained iron source.The self-strengthening is enabled by reaction-coupled diffusion,which makes possible the dynamic sequestration of iron from the in situ rusted steel,partially mimicking the iron accumulation process in a mussel.The emergence of iron-phenolic coordination bonds continuously improves modulus,hardness,and adhesion,achieving a strengthening efficiency comparable to mussel byssus.Interestingly,the bilayer design ensures long-term self-healing performance even during strengthening and a mechanically robust anticorrosion coating with an autonomic protection mechanism and gradually enhanced barrier properties during prolonged service.Our results provide a new venue for the design of stimuli-responsive smart materials characteristic of an open biological system and may serve as the basis for creating highly intelligent devices with sophisticated functionality.

Cement-inspired readily fabricated water-strengthened polymeric materials

Polymeric materials have penetrated all aspects of society and play an irreplaceable role.However,there is an inherent contradiction between their mechanical properties and processing behavior.Here,inspired by cement,a crucial construction material renowned for its excellent fabricating behavior and self-strengthening properties,we have developed dynamic crosslinked poly(oxime-urethane)(CPOU).The synthesized CPOU showed good self-healing ability and 3D printability owing to the dynamic dissociation and re-association of oxime-carbamate bonds.Simple objects printed through the fused deposition modeling technique were able to be readily assembled into complex architectures through intrinsic self-healing.Furthermore,the self-strengthening of CPOU was successfully realized through multiple-step tandem reactions.The dissociation of dynamic oxime-carbamate bonds produced–NCO groups,which reacted with the surrounding water to form polar urea bonds in the polymer network,leading to an increase in the tensile strength of CPOU from 11.95 to 19.37 MPa.This work not only develops the polymers with combined self-healing,facile fabricating,and self-strengthening properties but also provides a new molecular strategy to modulate the properties of polymers,which could be potentially applied in diverse areas.

Tensile Properties and Deformation Behaviors of a New Aluminum Alloy for High Pressure Die Casting

Effects of natural aging and test temperature on the tensile behaviors have been studied for a highperformance cast aluminum alloy Al–10Si–1.2Cu–0.7Mn. Based on self-strengthening mechanism and spheroidization microstructures, the alloy tested at room temperature（RT） exhibits higher 0.2% proof stress（YS） of 206 MPa, ultimate tensile strength（UTS） of 331 MPa and elongation of 10%. Increasing aging time improves the YS and UTS and reduces the ductility of the alloy. Further increasing aging time beyond72 h does not signi？cantly increase the tensile strengths. Increasing test temperature significantly decreases the tensile strengths and increases the ductility of the alloy. The UTS of the alloy can be estimated by using the hardness. The Portevin–Le Chatelier effect occurs at RT due to the interactions between solid solution atoms and dislocations. Similar behaviors occurring at 250℃ are attributed to dynamic strain aging mechanism. Increasing aging time leads to decrease in the strain-hardening exponent（n） value and increase in the strain-hardening coeficient（k） value. Increasing test temperature apparently decreases the n and k values. Eutectic phase particles cracking and debonding determine the fracture mechanism of the alloy. Final failure of the alloy mainly depends on the global instability（high temperature, necking） and local instability（RT, shearing）. Different tensile behaviors of the alloy are mainly attributed to different matrix strengths, phase particle strengths and damage rate.

Corrupted Infrastructure： Imperialism and Environmental Sovereignty in Shanghai, 1873-1911

The introduction of Western science in order to change physical and operational aspects of Shanghai＇s Huangpu River had been debated by Qing and Western officials since almost the beginning of its history as a Treaty Port. At stake in those debates was the perception of the river＇s proper use： as a natural barrier for military defense, or as a conduit for global trade. After the Western powers unified to militarily suppress the Boxer Uprising in 1900, they attained their long-awaited goal of the right to transform the river for global trade as part of Article 11 of the Boxer Protocol： the Junpuju （or Huangpu Conservancy Board） was created and authorized by the central government to make the Huangpu River navigable for shipping vessels. Although the Junpuju continued the ethos of earlier extra-bureaucratic organizations established during the Self-Strengthening Movement, after 1901 the organization bore the authority of the central government. During the era of the New Policies, Qing officials were intent on revising the original terms of river conservancy so that they would be more favorable to Chinese sovereignty. At the same time, imperialist rivalries among the Western powers ruptured the apparent unity of the earlier alliance during the suppression of the Boxer Uprising. Before long, Western corruption in the Huangpu River dredging was brought to the attention of Qing officials, who deftly used it to recover Qing control over certain parts of the body of the river.