The role of solution aggregates on the charge transport process of conjugated polymers in electronic devices has gained increasing attention; however, the correlation of the charge carrier mobilities ...between the solution aggregates and the solid‐state films remains elusive. Herein, three polymers, FBDOPV‐2T, FBDOPV‐2F2T, and FBDOPV‐4F2T, are designed and synthesized with distinct aggregation behavior in solution. By combining contact‐free ultrafast terahertz (THz) spectroscopy and field‐effect transistor measurements, we track the charge carrier mobility of the aggregates of these polymers from the solution to the thin‐film state. Remarkably, the mobility of these three polymers is found to follow nearly the same trend (FBDOPV‐2T>FBDOPV‐2F2T≫FBDOPV‐4F2T) in both solutions and thin‐film states. The quantitative mobility correlation indicates that the charge transport properties of solution aggregates play a critical role in determining the thin‐film charge transport properties and final device performance. Our results highlight the importance of investigating and controlling solution aggregation structures towards efficient organic electronic devices.
Different aggregation structures of three BDOPV‐based polymers in solution were obtained via subtle adjustment of the molecular structures. By employing contact‐free ultrafast terahertz (THz) spectroscopy, we directly reveal that the correlation of the charge carrier mobilities between the solution aggregates and the solid‐state films remains highly consistent.
Skin-inspired sensors have great potential applications in wearable and implantable devices to monitor human motions. Robust tissue adhesion, fatigue resistance, and biocompatibility are desired for
...in situ
signal capture and wireless transmission. Inspired by the mussel and zwitterionic adhesion mechanisms, we prepared novel stretchable, self-healing and polydopamine zwitterionic nanocomposite hydrogels that provide reversible and robust adhesion to tissues with a strength up to 19.4 kPa and a strain sensitivity of 4.3. The hydrogel sensors robustly adhere to organs like the heart, liver, and lungs to capture signals for remote monitoring and diagnostics through wireless transmission.
Stretchable, self-healing, and fatigue resistant polyzwitterionic nanocomposite hydrogels with polydopamine robustly adhere to the heart and lungs for
in situ
monitoring of dynamic motions through wireless transmission.
Porous metal–organic frameworks (MOFs) nanostructures constructed from metal ion/ion clusters and organic bridging ligands hold great promise for biomedicine applications. The developing of ...nanoagents achieving accurate diagnosis and improved therapeutic effect is highly desirable. Herein, a new‐style versatile zirconium‐ferriporphyrin metal–organic framework (Zr‐FeP MOF) nanoshuttles is reported using a facile one‐pot hydrothermal method. The Zr‐FeP MOF nanoshuttles enable simultaneously to generate abundant reactive oxygen species including hydroxyl radical (·OH) and singlet oxygen (1O2) under a near‐infrared (NIR) laser irradiation. Significant photothermal effect of Zr‐FeP MOF nanoshuttles with photothermal conversion efficiency high to 33.7% is also demonstrated. Under a single NIR laser irradiation, the Zr‐FeP MOF nanoshuttles loaded with heat shock protein 70 siRNA efficiently suppress the tumor growth both in vitro and in vivo owing to the synergistic effect of photodynamic therapy (PDT) and low‐temperature photothermal therapy (PTT). Meanwhile, it exhibits good photothermal imaging, computed tomography, and photoacoustic imaging tri‐mode tumor‐specific imaging capability for tumor accurate diagnosis. This work contributes to design “all‐in‐one” nanoagents that realize multimodal imaging diagnosis and PDT and low‐temperature PTT synergistic treatments.
A new‐style versatile zirconium‐ferriporphyrin metal–organic framework (Zr‐FeP MOF) nanoshuttles is reported using a facile one‐pot hydrothermal method. The resultant siRNA loaded polyethylene glycol‐modified Zr‐FeP MOF “all‐in‐one” nanoagents have realized photoacoustic imaging, photothermal imaging, and computed tomography imaging for multimodal imaging diagnosis and photodynamic therapy/low‐temperature photothermal therapy for synergistic treatments.
•We systematically reviewed the process, problems, measures and prospects of land system reform in China.•China's rural reform originated from its rural land system reform, and even the latter leads ...and promotes to the former to a certain extent.•China's land system reform can be roughly divided into five stages since 1949, and is now entering a period of deepening reform.•Land system reform can promote optimal allocation of resources, revitalize rural economy and coordinate human-land relationship.
Land system reform (LSR) helps to protect farmers' rights and interests and national food security. China is a country dominated by agriculture but insufficient arable land resources. The contradiction between man and land is prominent. To alleviate the man-land contradiction, the Chinese government has carried out a series of LSRs, especially in the past half century. Extensive and in-depth studies have been done on the process and stage characteristics of China's LSRs, but the systematic analysis on the necessity, problems and key measures to deepen the land system reform is still insufficient. Based on a systematic review of the history of the evolution of China's LSRs, this study firstly analyzed the key issues and new challenges existing in or arising from China's land system, then put forward the necessity of deepening the reform of land system, and discussed specific measures taken to deepen the reform of land system in China at present and finally pointed out the future LSR’s direction. The results show that China's rural LSR has gone through five stages in general since 1949. The key problems existing or arising from the current land system in China include unclear subject of land property right, serious inefficient utilization of land resources, rapid farmland conversion and conflict between farmers’ interests and land system. The dual land system in urban and rural areas has severely restricted the integration of social and economic development in this country. The Chinese government is actively promoting the reforms of rural agricultural land, collective operating construction land and homestead to further remove the dual institutional barriers that hinder the establishment of an integrated land trading market. The vision is good, but there is still a long way to go for China's LSR. The direction of China's rural LSR is to make the property rights relationship clearer, the farmland rights more complete, the transfer transactions more market-oriented and the property rights’ protection more equal. Deepening the rural LSRs is helpful to improve the efficiency of land resource utilization, safeguard the rights and interests of farmers, promote the coordination of human-land relationship, and inject new vitality and momentum into rural revitalization. Cooperative promotion of land resource capitalization reform and household registration system reform is the key area of land system reform in China in the future.
With a certified efficiency as high as 25.2%, perovskite has taken the crown as the highest efficiency thin film solar cell material. Unfortunately, serious instability issues must be resolved before ...perovskite solar cells (PSCs) are commercialized. Aided by theoretical calculation, an appropriate multifunctional molecule, 2,2‐difluoropropanediamide (DFPDA), is selected to ameliorate all the instability issues. Specifically, the carbonyl groups in DFPDA form chemical bonds with Pb2+ and passivate under‐coordinated Pb2+ defects. Consequently, the perovskite crystallization rate is reduced and high‐quality films are produced with fewer defects. The amino groups not only bind with iodide to suppress ion migration but also increase the electron density on the carbonyl groups to further enhance their passivation effect. Furthermore, the fluorine groups in DFPDA form both an effective barrier on the perovskite to improve its moisture stability and a bridge between the perovskite and HTL for effective charge transport. In addition, they show an effective doping effect in the HTL to improve its carrier mobility. With the help of the combined effects of these groups in DFPDA, the PSCs with DFPDA additive achieve a champion efficiency of 22.21% and a substantially improved stability against moisture, heat, and light.
Aided by theoretical calculations, a multifunctional 2,2‐difluoropropanediamide (DFPDA) molecule that bears carbonyl, amino, and fluorine groups is first introduced into the perovskite precursor, serving as a crystal growth mitigator, grain boundaries passivator, and surface protection material. With the help of the combined effects of multifunctional groups in DFPDA, the perovskite cells deliver an efficiency of 22.21% and improved stability.
A
bstract
We study reflected entropy as a mixed state correlation measure in black hole evaporation. As a measure for bipartite mixed states, reflected entropy can be computed between black hole and ...radiation, radiation and radiation, and even black hole and black hole. We compute reflected entropy curves in three different models: 3-side wormhole model, End-of-the-World (EOW) brane model in three dimensions and two-dimensional eternal black hole plus CFT model. For 3-side wormhole model, we find that reflected entropy is dual to island cross section. The reflected entropy between radiation and black hole increases at early time and then decreases to zero, similar to Page curve, but with a later transition time. The reflected entropy between radiation and radiation first increases and then saturates. For the EOW brane model, similar behaviors of reflected entropy are found.
We propose a quantum extremal surface for reflected entropy, which we call quantum extremal cross section. In the eternal black hole plus CFT model, we find a generalized formula for reflected entropy with island cross section as its area term by considering the right half as the canonical purification of the left. Interestingly, the reflected entropy curve between the left black hole and the left radiation is nothing but the Page curve. We also find that reflected entropy between the left black hole and the right black hole decreases and goes to zero at late time. The reflected entropy between radiation and radiation increases at early time and saturates at late time.
•We study the effects of liberal refugee-hosting policies and hosting large numbers of refugees on public goods provision and attitudes towards migration in Uganda from 2001 to 2020.•Uganda’s ...inclusive refugee hosting policies allow refugees to self-settle and have access to local public goods, while also ensuring that host communities benefit from refugee-related aid.•We combine longitudinal geospatial data on refugee settlements, primary and secondary education, healthcare, roads, citizen attitudes, and conflict.•We find that host community parishes that are closer to larger refugee settlements experience substantial positive spillovers, such as improved public school access, greater access to health clinics, more health utilization, and more road density.•While we might expect liberal hosting policies and large numbers of refugees to lead to public backlash, especially among poorer citizens, we find no backlash.
Large arrivals of refugees raise concerns about potential tensions with host communities, particularly if refugees are viewed as an out-group competing for limited material resources and crowding out public services. To address these concerns, calls have increased to allocate humanitarian aid in ways that also benefit host communities. This study tests whether the increased presence of refugees, when coupled with humanitarian aid, improves public service delivery for host communities and dampens potential social conflict. We study this question in Uganda, one of the largest and most inclusive refugee-hosting countries. The data combines geospatial information on refugee settlements with original longitudinal data on primary and secondary schools, road density, health clinics, and health utilization. We report two key findings. First, even after the 2014 arrival of over 1 million South Sudanese refugees, host communities with greater refugee presence experienced substantial improvements in local development. Second, using public opinion data, we find no evidence that refugee presence has been associated with more negative (or positive) attitudes towards migrants or migration policy.
Microplastic polystyrene foam has been found widely in the environment and is readily transported by wind or water. Beached and virgin foams of size 0.45–1 mm were prepared as sorbents to study ...oxytetracycline sorption. Enhanced adsorption were found in the beached foams compared to the virgin foams, corresponding to the higher specific surface area, micropore area and the degree of oxidation of the former. The Freundlich Kf value was 894 ± 84 ((mg kg−1) (mg L−1)1/n) for oxytetracycline adsorption on the beached foams, approximately twice as high as on the virgin foams. Effects of solution pH on adsorption to the beached foams were more pronounced to the virgin foams. Maximum adsorption occurred at pH 5 at which electrostatic repulsion between the microplastic surface and the oxytetracycline zwitterion was minimal, indicating that electrostatic interaction may have regulated adsorption. Moreover, H-bonding and multivalent cationic bridging mechanisms may also have affected the adsorption of oxytetracycline to the beached foams as reflected by the ionic effects. Adsorption was promoted more in the presence of humic acid than of fulvic acid, perhaps owing to π-π conjugation between the humic acid and the microplastic surface which led to enhanced electrostatic attraction for oxytetracycline. This study suggests that weathered polystyrene foams may act as carriers of antibiotics in the environment and their potential risks to ecosystem and human health merit further investigation.
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•Beached microplastics had greater hydrophilic functional groups on its surface.•Beached and virgin foams had different adsorption mechanism for oxytetracycline.•Oxytetracylcine had maximal sorption to the beached microplastics as zwitterion.•More promotion of oxytetracylcine sorption affected by humic acid than fulvic acid.
Beached polystyrene foams had enhanced affinity for oxytetracycline adsorption owing to their oxidized surfaces.
High conductivity, large mechanical strength, and elongation are important parameters for soft electronic applications. However, it is difficult to find a material with balanced electronic and ...mechanical performance. Here, a simple method is developed to introduce ion‐rich pores into strong hydrogel matrix and fabricate a novel ionic conductive hydrogel with a high level of electronic and mechanical properties. The proposed ionic conductive hydrogel is achieved by physically cross‐linking the tough biocompatible polyvinyl alcohol (PVA) gel as the matrix and embedding hydroxypropyl cellulose (HPC) biopolymer fibers inside matrix followed by salt solution soaking. The wrinkle and dense structure induced by salting in PVA matrix provides large stress (1.3 MPa) and strain (975%). The well‐distributed porous structure as well as ion migration–facilitated ion‐rich environment generated by embedded HPC fibers dramatically enhances ionic conductivity (up to 3.4 S m−1, at f = 1 MHz). The conductive hybrid hydrogel can work as an artificial nerve in a 3D printed robotic hand, allowing passing of stable and tunable electrical signals and full recovery under robotic hand finger movements. This natural rubber‐like ionic conductive hydrogel has a promising application in artificial flexible electronics.
A simple method to introduce ion‐rich pores into a strong hydrogel matrix and fabricate a novel ionic conductive hydrogel with a high‐level performance of both electronic and mechanical properties is developed, which has great potential for stretchable electronics and artificial tissue applications.
The Chinese government has grown increasingly invested in ecology in recent years. This paper discusses eco-efficiency using data envelopment analysis on 48 cities in Bohai Rim with special focus on ...the role of industrial structure upgrades. Based on the values from a super undesirable slack-based model, this study investigates eco-efficiency from temporal and spatial perspectives to reveal gaps among Bohai cities but an overall improvement in regional eco-efficiency. Moreover, this study adopts the Global and Local Moran's I to identify positive spatial autocorrelations and shows that most cites in Bohai Rim have high-high, low-low aggregation characteristics. Plus, the economic effects of per capita GDP, industrial structure upgrades on eco-efficiency are determined according to a spatial Durbin model. There appear to be negative spillover effects of industrial structure upgrades on surrounding cities, which reflects an industry transfer phenomenon related to eco-efficiency.
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•Undesirable super slack based measure is exploited to measure eco-efficiency.•There is an increasing polarized regional disparity in eco-efficiency in Bohai Rim.•Local improvement can be obtained in eco-efficiency under the influence of industry structure upgrading.•As a consequence of industrial transfer, negative effects arise in eco-efficiency for the surrounding cities.
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