This paper provides empirical evidence on the role of public health insurance in mitigating adverse outcomes associated with health shocks. Exploiting the rollout of a universal health insurance ...program in rural China, I find that total household income and consumption are fully insured against health shocks even without access to health insurance. Household labor supply is an important insurance mechanism against health shocks. Access to health insurance helps households to maintain investment in children's human capital during negative health shocks, which suggests that one benefit of health insurance could arise from reducing the use of costly smoothing mechanisms.
Motivated by the conflict between travelers’ habitual choice behavior and traffic information search behavior, in this paper, a behavioral experiment under different types of traffic information ...(i.e., per-trip traffic information and en-route traffic information) was designed to obtain data regarding car commuters’ daily route choices. Based on the observed data, participants’ route choices, habit strength, response time, and information search behaviors were analyzed. It is concluded that, in the beginning, the traffic information had a great influence on the habit participants’ route choices, let them think more, and made most of them switch from habit route to the best route (as recommended by traffic information); however, as time went on, the impact of traffic information declined, and several features of habits, such as automatically responding and repeated behavior, would reappear in some participants’ decision-making. Meanwhile, the different way of traffic information search behaviors (i.e., in active performance or in passive reception) could cause different information compliance ratios. These results would help to understand the interrelationship between car commuters’ daily route choice behaviors and traffic information search behaviors in short-term and in long-term, respectively, and provide an interesting starting point for the development of practical traffic information issuing strategies to enhance the impact of traffic information to alleviate traffic congestion during morning commuting.
This paper presents an efficient and compact
Matlab
code to solve three-dimensional topology optimization problems. The 169 lines comprising this code include finite element analysis, sensitivity ...analysis, density filter, optimality criterion optimizer, and display of results. The basic code solves minimum compliance problems. A systematic approach is presented to easily modify the definition of supports and external loads. The paper also includes instructions to define multiple load cases, active and passive elements, continuation strategy, synthesis of compliant mechanisms, and heat conduction problems, as well as the theoretical and numerical elements to implement general non-linear programming strategies such as SQP and MMA. The code is intended for students and newcomers in the topology optimization. The complete code is provided in Appendix
C
and it can be downloaded from
http://top3dapp.com
.
To date, high‐performance organic electrochemical transistors (OECTs) are almost all based on conjugated polymers. Small molecules can be synthesized with high purity without batch‐to‐batch ...variations. However, small molecules require highly crystalline films and good molecular packings to achieve high charge carrier mobilities. Such features make their films unsuitable for ion diffusion or make their molecular packing distorted due to ion diffusion, resulting in poor ion/charge carrier transport properties and slow response speed. Herein, it is proposed to construct small‐molecule‐based supramolecular polymers to address these issues. A molecule, namely TDPP‐RD‐G7 is designed, which exhibits J‐type self‐assembling behaviors and can form supramolecular polymers in solution and conjugated‐polymer‐like networks in solid state. More importantly, the porous supramolecular polymer networks allow fast ion diffusion and greatly increase the device response speeds. As a result, the TDPP‐RD‐G7 exhibits record fast response speeds (τon/τoff) of 10.5/0.32 ms with high figure‐of‐merit (µC*) of 5.88 F cm−1 V−1 s−1 in small‐molecule OECTs. This work reveals the possible reasons that hinder the response speeds in small‐molecule OECTs and demonstrates a new “supramolecular polymer” approach to high‐performance and fast‐response small‐molecule‐based OECTs.
A novel small‐molecule‐based J‐type self‐assembled supramolecular polymer approach is proposed to address the poor device performance and stability issues in small‐molecule‐based OECT materials. It is demonstrated that J‐type aggregation behavior can endow molecules with a “conjugated‐polymer‐like” network, benefit ion injection/diffusion, and enable high OECT performance and fast response.
Conspectus The development of next-generation lithium-based rechargeable batteries with high energy density, low cost, and improved safety is a great challenge with profound technological ...significance for portable electronics, electric vehicles, and grid-scale energy storage. Specifically, advanced lithium battery chemistries call for a paradigm shift to electrodes with high Li to host ratio based on a conversion or alloying mechanism, where the increased capacity is often accompanied by drastic volumetric changes, significant bond breaking, limited electronic/ionic conductivity, and unstable electrode/electrolyte interphase. Fortunately, the rapid progress of nanotechnology over the past decade has been offering battery researchers effective means to tackle some of the most pressing issues for next-generation battery chemistries. The major applications of nanotechnology in batteries can be summarized as follows: First, by reduction of the dimensions of the electrode materials, the cracking threshold of the material upon lithiation can be overcome, at the same time facilitating electron/ion transport within the electrode. Second, nanotechnology also provides powerful methods to generate various surface-coating and functionalization layers on electrode materials, protecting them from side reactions in the battery environment. Finally, nanotechnology gives people the flexibility to engineer each and every single component within a battery (separator, current collector, etc.), bringing novel functions to batteries that are unachievable by conventional methods. Thus, this Account aims to highlight the crucial role of nanotechnology in advanced battery systems. Because of the limited space, we will mainly assess representative examples of rational nanomaterials design with complexity for silicon and lithium metal anodes, which have shown great promise in constraining their large volume changes and the repeated solid–electrolyte interphase formation during cycling. Noticeably, the roadmap delineating the gradual improvement of silicon anodes with a span of 11 generations of materials designs developed in our group is discussed in order to reflect how nanotechnology could guide battery research step by step toward practical applications. Subsequently, we summarize efforts to construct nanostructured composite sulfur cathodes with improved electronic conductivity and effective soluble species encapsulation for maximizing the utilization of active material, cycle life, and system efficiency. We emphasize carbon-based materials and, importantly, materials with polar surfaces for sulfur entrapment. We then briefly discuss nanomaterials strategies to improve the ionic conductivity of solid polymer electrolytes by means of incorporating high-surface-area and, importantly, high-aspect-ratio secondary-phase fillers for continuous, low-tortuosity ionic transport pathways. Finally, critical innovations that have been brought to the area of grid-scale energy storage and battery safety by nanotechnology are also succinctly reviewed.
Solid polymer electrolytes are light-weight, flexible, and non-flammable and provide a feasible solution to the safety issues facing lithium-ion batteries through the replacement of organic liquid ...electrolytes. Substantial research efforts have been devoted to achieving the next generation of solid-state polymer lithium batteries. Herein, we provide a review of the development of solid polymer electrolytes and provide comprehensive insights into emerging developments. In particular, we discuss the different molecular structures of the solid polymer matrices, including polyether, polyester, polyacrylonitrile, and polysiloxane, and their interfacial compatibility with lithium, as well as the factors that govern the properties of the polymer electrolytes. The discussion aims to give perspective to allow the strategic design of state-of-the-art solid polymer electrolytes, and we hope it will provide clear guidance for the exploration of high-performance lithium batteries.
Abstract
Doping has been widely used to control the charge carrier concentration in organic semiconductors. However, in conjugated polymers, n-doping is often limited by the tradeoff between doping ...efficiency and charge carrier mobilities, since dopants often randomly distribute within polymers, leading to significant structural and energetic disorder. Here, we screen a large number of polymer building block combinations and explore the possibility of designing n-type conjugated polymers with good tolerance to dopant-induced disorder. We show that a carefully designed conjugated polymer with a single dominant planar backbone conformation, high torsional barrier at each dihedral angle, and zigzag backbone curvature is highly dopable and can tolerate dopant-induced disorder. With these features, the designed diketopyrrolopyrrole (DPP)-based polymer can be efficiently n-doped and exhibit high n-type electrical conductivities over 120 S cm
−1
, much higher than the reference polymers with similar chemical structures. This work provides a polymer design concept for highly dopable and highly conductive polymeric semiconductors.
Optical physical unclonable functions (PUFs) have been proven to be one of the most effective anti‐counterfeiting strategies. However, optical PUFs endowed with flexibility and biocompatibility have ...not been developed, limiting their application scenarios. Herein, biocompatible and flexible optical PUF labels are developed by randomly embedding microdiamonds in silk fibroin films. The PUF labels can be conformally attached onto the surface of complex shaped objects, providing the desired protection against fake and interior products. In this system, silk fibroin films serve as a flexible and biocompatible substrate, while the Raman signal of the microdiamonds serves as response of the excitation. The extremely high stability and random distribution of the microdiamonds ensure the performance of PUFs, and the maximum encoding capability of 210000 is finally realized. The cytotoxicity analysis results also verify the biosafety of the PUF system. In addition, the as‐prepared PUF labels are attached onto the surface of polyethylene material, and human skin, and even have been implanted under chicken skin tissue, promising their practical applications.
Flexible and biocompatible physical unclonable function labels are designed and demonstrated by using microdiamonds as the response of the excitation and silk fibroin films as a flexible and biocompatible substrate, which have been applied for protection against fake objects with complex shapes.
Reactive oxygen species (ROS) are generated in the body and related to many pathophysiological processes. Hence, detection of ROS is indispensable in understanding, diagnosis, and treatment of many ...diseases. Here, near‐infrared (NIR) chemiluminescent (CL) carbon nanodots (CDs) are fabricated for the first time and their CL quantum yield can reach 9.98 × 10−3 einstein mol−1, which is the highest value ever reported for CDs until now. Nanointegration of NIR CDs and peroxalate (P‐CDs) through the bridging effect of amphiphilic triblock copolymer can serve as turn‐on probes for the detection and imaging of hydrogen peroxide (H2O2). Considering high efficiency and large penetration depth of NIR photons, the P‐CDs are employed in bioimaging H2O2 in vitro and in vivo, and the detection limit can reach 5 × 10−9 m, among the best reported of CDs‐based sensors. Moreover, imaging of inflammatory H2O2 in a mouse model of peritonitis is achieved by employing the P‐CDs as sensors. The results may provide a clue for the diagnosis and treatment of inflammation or cancers employing CL CDs as sensors.
NIR carbon nanodots (CDs) with efficient chemiluminescence are developed. Nanointegration of NIR CDs and peroxalate can serve as turn‐on probes for bioimaging of exogenous and endogenous H2O2 in vitro and in vivo with the detection limit is 5 × 10−9 m. Bioimaging inflammatory H2O2 in a mouse model of peritonitis is achieved.
Here, a pair of A1–D–A2–D–A1 unfused ring core‐based nonfullerene small molecule acceptors (NF‐SMAs), BO2FIDT‐4Cl and BT2FIDT‐4Cl is synthesized, which possess the same terminals (A1) and ...indacenodithiophene unit (D), coupling with different fluorinated electron‐deficient central unit (difluorobenzoxadiazole or difluorobenzothiadiazole) (A2). BT2FIDT‐4Cl exhibits a slightly smaller optical bandgap of 1.56 eV, upshifted highest occupied molecular orbital energy levels, much higher electron mobility, and slightly enhanced molecular packing order in neat thin films than that of BO2FIDT‐4Cl. The polymer solar cells (PSCs) based on BT2FIDT‐4Cl:PM7 yield the best power conversion efficiency (PCE) of 12.5% with a Voc of 0.97 V, which is higher than that of BO2FIDT‐4Cl‐based devices (PCE of 10.4%). The results demonstrate that the subtle modification of A2 unit would result in lower trap‐assisted recombination, more favorable morphology features, and more balanced electron and hole mobility in the PM7:BT2FIDT‐4Cl blend films. It is worth mentioning that the PCE of 12.5% is the highest value in nonfused ring NF‐SMA‐based binary PSCs with high Voc over 0.90 V. These results suggest that appropriate modulation of the quinoid electron‐deficient central unit is an effective approach to construct highly efficient unfused ring NF‐SMAs to boost PCE and Voc simultaneously.
An effective intramolecular locking strategy is designed by introducing the central electron‐deficient quinoid to unfused ring A1–D–A2–D–A1‐type nonfullerene small molecule acceptors (NF‐SMAs). The polymer solar cells (PSCs) based on BT2FIDT‐4Cl with difluorobenzothiadiazole central unit show a power conversion efficiency (PCE) of 12.5% with Voc of near 1 V. This is the best result for nonfused ring NF‐SMAs with electron‐deficient A2 unit in binary PSCs.
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