Rhythmic behavior represents one of the most striking and ubiquitous manifestations of functional evolution for a wide class of natural and man-made systems. The emergence of diverse (ar)rhythmic ...dynamics can be well understood by models of coupled dynamical networks, where the interplay between the intrinsic dynamics of a single unit and the coupling functions plays a critical role in shaping a vast repertoire of collective behaviors. Under certain circumstances, all the individual dynamical systems may cease their oscillations totally when coupled, which results in the emergence of oscillation quenching in coupled oscillatory systems. Macroscopic oscillations of coupled dynamical networks can also be gradually weakened and even completely quenched via aging transition. Oscillation reviving, an inverse process of quenching and aging, refers to the restoration of rhythmic activity of coupled dynamical networks from the phenomena of quenching and aging. The study on quenching, aging, and reviving of rhythmic behaviors in coupled dynamical networks has developed into an active and rapidly evolving area of research with a wide variety of applications, where tremendous progresses with vital insights have been witnessed in the last decade. In this review, we endeavour to provide an exhaustive overview on the most important aspects of quenching, aging, and reviving in coupled dynamical networks ranging from theories to experiments and applications. The prevailing knowledge is integrated and pulled together to make the relevant results and methods more generally accessible for researchers in distinct communities of science and technology. Relevant open issues and challenges that deserve of special attentions are highlighted for future study. The present review should stimulate deeper investigations on the collapse and revival of macroscopic rhythmic behaviors, which will enlighten our understanding on evading irreversible failures of coupled dynamical networks and even guide us to identify the precursors of critical transitions. Our work will foster further studies on the physical principles of collective rhythms that robustly emerge in nature and real life.
Quasi‐2D layered organometal halide perovskites have recently emerged as promising candidates for solar cells, because of their intrinsic stability compared to 3D analogs. However, relatively low ...power conversion efficiency (PCE) limits the application of 2D layered perovskites in photovoltaics, due to large energy band gap, high exciton binding energy, and poor interlayer charge transport. Here, efficient and water‐stable quasi‐2D perovskite solar cells with a peak PCE of 18.20% by using 3‐bromobenzylammonium iodide are demonstrated. The unencapsulated devices sustain over 82% of their initial efficiency after 2400 h under relative humidity of ≈40%, and show almost unchanged photovoltaic parameters after immersion into water for 60 s. The robust performance of perovskite solar cells results from the quasi‐2D perovskite films with hydrophobic nature and a high degree of electronic order and high crystallinity, which consists of both ordered large‐bandgap perovskites with the vertical growth in the bottom region and oriented small‐bandgap components in the top region. Moreover, due to the suppressed nonradiative recombination, the unencapsulated photovoltaic devices can work well as light‐emitting diodes (LEDs), exhibiting an external quantum efficiency of 3.85% and a long operational lifetime of ≈96 h at a high current density of 200 mA cm−2 in air.
High‐crystallinity quasi‐2D perovskite films with oriented structure are fabricated by using 3‐bromobenzylammonium iodide, leading to perovskite solar cells with a high efficiency of 18.20%. Moreover, the unencapsulated devices exhibit excellent moisture resistance, retaining 82% of the initial efficiency after 2400 h under ambient conditions. Even after immersion into water for 60 s, the unsealed device shows little decay.
•Single- truck crashes and multi-vehicle truck-related crashes have different influencing factors.•Truck weights have statistically heterogeneous effects on accident severity in both types.•The ...spatial dependency and the time of day effects are statistically significant.
This paper investigates the differences between single-vehicle and multi-vehicle truck crashes in New York City. The random parameter models take into account the time of day effect, the heterogeneous truck weight effect and other influencing factors such as crash characteristics, driver and vehicle characteristics, built environment factors and traffic volume attributes. Based on the results from the co-location quotient analysis, a spatial generalized ordered probit model is further developed to investigate the potential spatial dependency among single-vehicle truck crashes. The sample is drawn from the state maintained incident data, the publicly available Smart Location Data, and the BEST Practices Model (BPM) data from 2008 to 2012. The result shows that there exists a substantial difference between factors influencing single-vehicle and multi-vehicle truck crash severity. It also suggests that heterogeneity does exist in the truck weight, and it behaves differently in single-vehicle and multi-vehicle truck crashes. Furthermore, individual truck crashes are proved to be spatially dependent events for both single and multi-vehicle crashes. Last but not least, significant time of day effects were found for PM and night time slots, crashes that occurred in the afternoons and at nights were less severe in single-vehicle crashes, but more severe in multi-vehicle crashes.
Microplastics (MPs) are ubiquitous in the environment and pose substantial threats to the water ecosystem. However, the impact of natural aging of MPs on their toxicity has rarely been considered. ...This study found that visible light irradiation with hydrogen peroxide at environmentally relevant concentration for 90 days significantly altered the physicochemical properties and mitigated the toxicity of polyamide (PA) fragments to infantile zebrafish. The size of PA particles was reduced from ∼8.13 to ∼6.37 μm, and nanoparticles were produced with a maximum yield of 5.03%. The end amino groups were volatilized, and abundant oxygen-containing groups (e.g., hydroxyl and carboxyl) and carbon-centered free radicals were generated, improving the hydrophilicity and colloidal stability of degraded MPs. Compared with pristine PA, the depuration of degraded MPs mediated by multixenobiotics resistance was much quicker, leading to markedly lower bioaccumulation in fish and weaker inhibition on musculoskeletal development. By integrating transcriptomics and transgenic zebrafish Tg(lyz:EGFP) tests, differences in macrophages-triggered proinflammatory effects, apoptosis via IL-17 signaling pathway, and antioxidant damages were identified as the underlying mechanisms for the attenuated toxicity of degraded MPs. This work highlights the importance of natural degradation on the toxicity of MPs, which has great implications for risk assessment of MPs.
This study investigates the influence of freeze-thaw (FT) cycles on the (i) microstructure, (ii) soil water characteristics, and (iii) sensitivity of the volumetric strain and mechanical properties ...to moisture content for a compacted clay. The mechanical properties herein include resilient modulus (MR), unconfined compression strength (qu), and reloading modulus (E1%) and stress (Su1%) at 1% strain. Specimens were compacted at optimum moisture content and subjected to different FT cycles (i.e. 0, 1, 3, and 10 cycles). Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) were performed to reveal the evolution of the microstructure during FT cycles. Specimens were then wetted or dried to different suction (s) and degree of saturation (Sr) values to obtain the (i) soil water characteristics using filter paper method and (ii) MR, qu, E1%, and Su1% using cyclic and static triaxial tests. Experimental results demonstrate that FT cycles induce cracks that are tens of microns in dimension, which reduce specimens' water retention capacity and the volumetric strain upon wetting and drying. Mechanical properties also reduce significantly and become less sensitive to the s and Sr after FT cycles. A model was used to predict the variation of the MR, qu, E1% and Su1% with s and Sr for specimens subjected to different FT cycles. An attenuation coefficient χFT was proposed to describe the FT-induced degradation in the qu, E1%, Su1%, and MR. It was found that the χFT for different mechanical properties are consistent. The evolution of their χFT with FT cycles can be described by a uniform empirical equation. The study presented in this paper is useful for the rational understanding and prediction of the hydromechanical behaviors of compacted clay taking account of the influence of FT cycles.
•Freeze-thaw (FT) cycles generate cracks that are tens of microns in dimension.•FT cycles reduce soils' water retention capacity and mechanical properties.•Mechanical properties are less sensitive to moisture changes after FT cycles.•Models were proposed to predict mechanical properties considering FT influences.
This paper constructs a general equilibrium spatial urban model and measures city geometric compactness using the patch‐shape index based on evidence from satellite imagery and basic vector maps of ...China. It adopts the ordinary least squares and instrumental variable approaches to examine the effect of city shape on the urban development of 279 Chinese cities at or above the prefecture level. The empirical results show that there was a significant negative correlation between city shape and economic outcomes. Specifically, every 1 percentage point increase in the patch‐shape index led to a decrease in city‐scale GDP by 0.009 percent, housing prices by 0.044 percent, and wages by 0.024 percent. More compact urban layouts attracted an inflow of households and firms, stimulated city economic growth, and were associated with increased housing prices and wage rates. The paper considers the cities' initial conditions, trends in population changes (expanding, shrinking, and stagnant cities), and geographic factors, and finds that the results are robust. An array of policy implications can be drawn from the research.
The lack of efficient tools to image non-repetitive genes in living cells has limited our ability to explore the functional impact of the spatiotemporal dynamics of such genes. Here, we addressed ...this issue by developing a CRISPR-Tag system using one to four highly active sgRNAs to specifically label protein-coding genes with a high signal-to-noise ratio for visualization by wide-field fluorescence microscopy. Our approach involves assembling a CRISPR-Tag within the intron region of a fluorescent protein and then integrating this cassette to N- or C-terminus of a specific gene, which enables simultaneous real-time imaging of protein and DNA of human protein-coding genes, such as HIST2H2BE, LMNA and HSPA8 in living cells. This CRISPR-Tag system, with a minimal size of ~250 bp DNA tag, represents an easily and broadly applicable technique to study the spatiotemporal organization of genomic elements in living cells.
A novel and sensitive method for the selective determination of Cr(VI) and non-chromatographic speciation of Cr(VI) and Cr(III) was developed based on chemical vapor generation (CVG) in KBH4-acid ...system for sample introduction into an inductively coupled plasma mass spectrometer (ICP-MS) for detection. The CVG of Cr(VI), rather than Cr(III), was found to be remarkably enhanced in the presence of sodium diethylaminodithioformate (DDTC). After the oxidation of Cr(III) to Cr(VI) by KMnO4, the quantitation of Cr(III) could be obtained based on the difference between the concentration of total chromium and that of Cr(VI). Parameters affecting the CVG reaction and determination of Cr(VI) were evaluated in detail, including the concentrations of DDTC, hydrochloric acid and KBH4, the sample flow rate, as well as the length of reaction and transferring tubing. Under optimal conditions, the CVG efficiency and the limit of detection (LOD) of Cr(VI) were found to be 28% and 0.2 ng mL−1, respectively. The relative standard deviations for seven replicate measurements of 20 ng mL−1 of Cr(Ⅵ) was 1.8%. Furthermore, with excess DDTC (100 μg mL−1) added to the test solutions, possible interferences from Cu2+ (up to 400 ng mL−1) could be eliminated. The proposed method was thus successfully applied to the determination of Cr(VI) in three real water samples and one certified reference water sample, as well as two simulated water samples of Cr(VI) and Cr(III), all with satisfactory results. The possible reasons were discussed for the varied degrees of enhancement between Cr(III) and Cr(VI).
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•Trace chromium was determined by chemical vapor generation-ICPMS.•Chemical vapor generation efficiency of Cr(VI) was selectively enhanced with DDTC.•Non-chromatographic speciation analysis of Cr(III) and Cr(VI) can be realized via oxidation of Cr(III) to Cr(VI) by KMnO4.•It was used for quantitation of Cr(VI) and speciation analysis of Cr(VI)/Cr(III) in water samples.
Efficiency roll-off is a major issue for most types of light-emitting diodes (LEDs), and its origins remain controversial. Here we present investigations of the efficiency roll-off in perovskite LEDs ...based on two-dimensional layered perovskites. By simultaneously measuring electroluminescence and photoluminescence on a working device, supported by transient photoluminescence decay measurements, we conclude that the efficiency roll-off in perovskite LEDs is mainly due to luminescence quenching which is likely caused by non-radiative Auger recombination. This detrimental effect can be suppressed by increasing the width of quantum wells, which can be easily realized in the layered perovskites by tuning the ratio of large and small organic cations in the precursor solution. This approach leads to the realization of a perovskite LED with a record external quantum efficiency of 12.7%, and the efficiency remains to be high, at approximately 10%, under a high current density of 500 mA cm
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This paper reports a facile and scalable process to achieve high performance red perovskite light‐emitting diodes (LEDs) by introducing inorganic Cs into multiple quantum well (MQW) perovskites. The ...MQW structure facilitates the formation of cubic CsPbI3 perovskites at low temperature, enabling the Cs‐based QWs to provide pure and stable red electroluminescence. The versatile synthesis of MQW perovskites provides freedom to control the crystallinity and morphology of the emission layer. It is demonstrated that the inclusion of chloride can further improve the crystallization and consequently the optical properties of the Cs‐based MQW perovskites, inducing a low turn‐on voltage of 2.0 V, a maximum external quantum efficiency of 3.7%, a luminance of ≈440 cd m−2 at 4.0 V. These results suggest that the Cs‐based MQW LED is among the best performing red perovskite LEDs. Moreover, the LED device demonstrates a record lifetime of over 5 h under a constant current density of 10 mA cm−2. This work suggests that the MQW perovskites is a promising platform for achieving high performance visible‐range electroluminescence emission through high‐throughput processing methods, which is attractive for low‐cost lighting and display applications.
High performance red perovskite light‐emitting diodes (LEDs) are achieved by introducing cesium in multiple‐quantum‐well perovskites. The device exhibits a low turn‐on voltage of 2.0 V, a peak external quantum efficiency of 3.7%, a maximum luminance of 440 cd m−2, and lifetime of 5 h under 10 mA cm−2 constant current density, presenting one of the best performing red perovskite LEDs.
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