State Control and the Effects of Foreign Relations on Bilateral Trade

Do states use trade to reward and punish partners? WTO rules and the pressures of globalization restrict states’ capacity to manipulate trade policies, but we argue that governments can link political goals with economic outcomes using less direct avenues of influence over firm behavior. Where governments intervene in markets, politicization of trade is likely to occur. In this paper, we examine one important form of government control: state ownership of firms. Taking China and India as examples, we use bilateral trade data by firm ownership type, as well as measures of bilateral political relations based on diplomatic events and UN voting to estimate the effect of political relations on import and export flows. Our results support the hypothesis that imports controlled by state-owned enterprises (SOEs) exhibit stronger responsiveness to political relations than imports controlled by private enterprises. A more nuanced picture emerges for exports; while India’s exports through SOEs are more responsive to political tensions than its flows through private entities, the opposite is true for China. This research holds broader implications for how we should think about the relationship between political and economic relations going forward, especially as a number of countries with partially state-controlled economies gain strength in the global economy

Structural Spectrum of 2D Materials in Solution: Toward Establishing 2D Assemblies' Digital Factory

The numerous hierarchical architectures of 2D assemblies endow them with a new dimension to realize novel properties. From theoretical perspective, freedoms stem from in plane and out plane mechanical properties of 2D materials separately, which makes 2D materials embrace more than one persistence length giving rise to the diverse morphologies. However, the understanding of 3D architecture formation in 2D assemblies is still in its infancy. In fact, there is even no theoretical classification or reference to help clarify structural difference among numerous experimental obtained 2D assemblies. Based on the theoretical model composed by 2D sheets and Lennard Jones liquids, solution concentration dependence of 2D materials conformation is systematically studied, and a ln K behavior is uncovered that can realize the theoretical conformation prediction of 2D materials. More importantly, the digital production line (solution processing procedure) is set up toward establishing the 2D assemblies' digital factory. The obtained structures may provide a reference to 2D assemblies, which benefits the understanding of the structural difference among different experiments and even help to guide the experimental design of 2D assemblies with targeted architectures and properties

Self-Healing, Highly Sensitive Electronic Sensors Enabled by Metal–Ligand Coordination and Hierarchical Structure Design

Electronic sensors capable of capturing mechanical deformation are highly desirable for the next generation of artificial intelligence products. However, it remains a challenge to prepare self-healing, highly sensitive, and cost-efficient sensors for both tiny and large human motion monitoring. Here, a new kind of self-healing, sensitive, and versatile strain sensors has been developed by combining metal–ligand chemistry with hierarchical structure design. Specifically, a self-healing and nanostructured conductive layer is deposited onto a self-healing elastomer substrate cross-linked by metal–ligand coordinate bonds, forming a hierarchically structured sensor. The resultant sensors exhibit high sensitivity, low detection limit (0.05% strain), remarkable self-healing capability, as well as excellent reproducibility. Notably, the self-healed sensors are still capable to precisely capture not only tiny physiological activities (such as speech, swallowing, and coughing) but also large human motions (finger and neck bending, touching). Moreover, harsh treatments, including bending over 50000 times and mechanical washing, could not influence the sensitivity and stability of the self-healed sensors in human motion monitoring. This proposed strategy via alliance of metal–ligand chemistry and hierarchical structure design represents a general approach to manufacturing self-healing, robust sensors, and other electronic devices

Spirally Structured Conductive Composites for Highly Stretchable, Robust Conductors and Sensors

Flexible and stretchable electronics are highly desirable for next generation devices. However, stretchability and conductivity are fundamentally difficult to combine for conventional conductive composites, which restricts their widespread applications especially as stretchable electronics. Here, we innovatively develop a new class of highly stretchable and robust conductive composites via a simple and scalable structural approach. Briefly, carbon nanotubes are spray-coated onto a self-adhesive rubber film, followed by rolling up the film completely to create a spirally layered structure within the composites. This unique spirally layered structure breaks the typical trade-off between stretchability and conductivity of traditional conductive composites and, more importantly, restrains the generation and propagation of mechanical microcracks in the conductive layer under strain. Benefiting from such structure-induced advantages, the spirally layered composites exhibit high stretchability and flexibility, good conductive stability, and excellent robustness, enabling the composites to serve as highly stretchable conductors (up to 300% strain), versatile sensors for monitoring both subtle and large human activities, and functional threads for wearable electronics. This novel and efficient methodology provides a new design philosophy for manufacturing not only stretchable conductors and sensors but also other stretchable electronics, such as transistors, generators, artificial muscles, etc

Dialysis-Free and in Situ Doping Synthesis of Polypyrrole@Cellulose Nanowhiskers Nanohybrid for Preparation of Conductive Nanocomposites with Enhanced Properties

The separation of cellulose nanowhiskers (CNs) from hydrolysis acid and the harmless disposal of the residual hydrolysis acid are two main obstacles that hinder the large-scale production of CNs and CNs based nanocomposites. In this work, the hydrolysis products of CNs without further separation were used as the starting materials for preparation of a CNs supported polypyrrole (PPy@CNs) nanohybrid. During this one-pot synthesis process, the residual hydrolysis acid acted as a doping agent for the synthesized PPy, endowing PPy@CNs nanohybrid with electrical conductivity. Interestingly, the PPy@CNs nanohybrid could be easily isolated from the polymerization products due to the decreased surface charge. Meanwhile, the PPy@CNs nanohybrid showed good suspension stability in alkaline natural rubber (NR) latex, which facilitated the construction of continuous PPy@CNs conductive network in the NR matrix. This PPy@CNs filled NR nanocomposite showed significant improvement in electrical conductivity and mechanical properties when compared with neat PPy/NR composites, and exhibited similar performance to that of PPy@CNs-0 (CNs was isolated by dialysis and virgin doping agent was used) filled NR nanocomposites. The straightforwardness and sustainability of this dialysis-free and in situ doping synthesis of the PPy@CNs nanohybrid should significantly facilitate the scalable fabrication and application of CNs based conductive nanocomposites with high performance

Spirally Structured Conductive Composites for Highly Stretchable, Robust Conductors and Sensors

Flexible and stretchable electronics are highly desirable for next generation devices. However, stretchability and conductivity are fundamentally difficult to combine for conventional conductive composites, which restricts their widespread applications especially as stretchable electronics. Here, we innovatively develop a new class of highly stretchable and robust conductive composites via a simple and scalable structural approach. Briefly, carbon nanotubes are spray-coated onto a self-adhesive rubber film, followed by rolling up the film completely to create a spirally layered structure within the composites. This unique spirally layered structure breaks the typical trade-off between stretchability and conductivity of traditional conductive composites and, more importantly, restrains the generation and propagation of mechanical microcracks in the conductive layer under strain. Benefiting from such structure-induced advantages, the spirally layered composites exhibit high stretchability and flexibility, good conductive stability, and excellent robustness, enabling the composites to serve as highly stretchable conductors (up to 300% strain), versatile sensors for monitoring both subtle and large human activities, and functional threads for wearable electronics. This novel and efficient methodology provides a new design philosophy for manufacturing not only stretchable conductors and sensors but also other stretchable electronics, such as transistors, generators, artificial muscles, etc

Highly Sensitive, Stretchable, and Wash-Durable Strain Sensor Based on Ultrathin Conductive Layer@Polyurethane Yarn for Tiny Motion Monitoring

Strain sensors play an important role in the next generation of artificially intelligent products. However, it is difficult to achieve a good balance between the desirable performance and the easy-to-produce requirement of strain sensors. In this work, we proposed a simple, cost-efficient, and large-area compliant strategy for fabricating highly sensitive strain sensor by coating a polyurethane (PU) yarn with an ultrathin, elastic, and robust conductive polymer composite (CPC) layer consisting of carbon black and natural rubber. This CPC@PU yarn strain sensor exhibited high sensitivity with a gauge factor of 39 and detection limit of 0.1% strain. The elasticity and robustness of the CPC layer endowed the sensor with good reproducibility over 10 000 cycles and excellent wash- and corrosion-resistance. We confirmed the applicability of our strain sensor in monitoring tiny human motions. The results indicated that tiny normal physiological activities (including pronunciation, pulse, expression, swallowing, coughing, etc.) could be monitored using this CPC@PU sensor in real time. In particular, the pronunciation could be well parsed from the recorded delicate speech patterns, and the emotions of laughing and crying could be detected and distinguished using this sensor. Moreover, this CPC@PU strain-sensitive yarn could be woven into textiles to produce functional electronic fabrics. The high sensitivity and washing durability of this CPC@PU yarn strain sensor, together with its low-cost, simplicity, and environmental friendliness in fabrication, open up new opportunities for cost-efficient fabrication of high performance strain sensing devices

Flame Retardant, Heat Insulating Cellulose Aerogels from Waste Cotton Fabrics by in Situ Formation of Magnesium Hydroxide Nanoparticles in Cellulose Gel Nanostructures

Cellulose aerogels with low density, high mechanical strength, and low thermal conductivity are promising candidates for environmentally friendly heat insulating materials. The application of cellulose aerogels as heat insulators in building and domestic appliances, however, is hampered by their highly flammable characteristics. In this work, flame retardant cellulose aerogels were fabricated from waste cotton fabrics by in situ synthesis of magnesium hydroxide nanoparticles (MH NPs) in cellulose gel nanostructures, followed by freeze-drying. Our results demonstrated that the three-dimensionally nanoporous cellulose gel prepared from the NaOH/urea solution could serve as scaffold/template for the nonagglomerated growth of MH NPs. The prepared hybridized cellulose aerogels showed excellent flame retardancy, which could extinguish within 40 s. Meanwhile, the thermal conductivity of the composite aerogel increased moderately from 0.056 to 0.081 W m^–1 k^–1 as the specific surface area decreased slightly from 38.8 to 37.6 cm² g^–1, which indicated that the excellent heat insulating performance of cellulose aerogel was maintained. Because the concepts of the process are simple and biomass wastes are sustainable and readily available at low cost, the present approach is suitable for industrial scale production and has great potential in the future of green building materials

Highly Sensitive, Stretchable, and Wash-Durable Strain Sensor Based on Ultrathin Conductive Layer@Polyurethane Yarn for Tiny Motion Monitoring

Strain sensors play an important role in the next generation of artificially intelligent products. However, it is difficult to achieve a good balance between the desirable performance and the easy-to-produce requirement of strain sensors. In this work, we proposed a simple, cost-efficient, and large-area compliant strategy for fabricating highly sensitive strain sensor by coating a polyurethane (PU) yarn with an ultrathin, elastic, and robust conductive polymer composite (CPC) layer consisting of carbon black and natural rubber. This CPC@PU yarn strain sensor exhibited high sensitivity with a gauge factor of 39 and detection limit of 0.1% strain. The elasticity and robustness of the CPC layer endowed the sensor with good reproducibility over 10 000 cycles and excellent wash- and corrosion-resistance. We confirmed the applicability of our strain sensor in monitoring tiny human motions. The results indicated that tiny normal physiological activities (including pronunciation, pulse, expression, swallowing, coughing, etc.) could be monitored using this CPC@PU sensor in real time. In particular, the pronunciation could be well parsed from the recorded delicate speech patterns, and the emotions of laughing and crying could be detected and distinguished using this sensor. Moreover, this CPC@PU strain-sensitive yarn could be woven into textiles to produce functional electronic fabrics. The high sensitivity and washing durability of this CPC@PU yarn strain sensor, together with its low-cost, simplicity, and environmental friendliness in fabrication, open up new opportunities for cost-efficient fabrication of high performance strain sensing devices