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Ultra‐broadband near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) have great application prospects in research and industrial fields. However, simultaneously achieving highly efficient and ultra‐broad NIR emission in phosphor material remains a challenge. Herein, an ultra‐broadband NIR emission in the range of 800–1200 nm with ultra‐high emission efficiency of up to 64.2% is first achieved by substituting the Sc3+ site in Cs2NaScCl6 perovskite single‐crystal with a Cr3+ ion. By combining the experimental results with first‐principles calculations, an efficient charge transfer sensitization process from host to Cr3+ is found to be the fundamental reason for the ultra‐high NIR emission efficiency. Benefiting from the excellent efficiency and superior chemical resistance to heat and UV radiation, an ultra‐broadband NIR pc‐LED made of this phosphor demonstrates great potential in biomedical imaging, nondestructive testing, and night‐vision devices. [ABSTRACT FROM AUTHOR]

Exciton localization is an approach for preparing highly luminescent semiconductors. However, realizing strongly localized excitonic recombination in low‐dimensional materials such as two‐dimensional (2D) perovskites remains challenging. Herein, we first propose a simple and efficient Sn2+ vacancy (VSn) tuning strategy to enhance excitonic localization in 2D (OA)2SnI4 (OA=octylammonium) perovskite nanosheets (PNSs), increasing their photoluminescence quantum yield (PLQY) to ≈64 %, which is among the highest values reported for tin iodide perovskites. Combining experimental with first‐principles calculation results, we confirm that the significantly increased PLQY of (OA)2SnI4 PNSs is primarily due to self‐trapped excitons with highly localized energy states induced by VSn. Moreover, this universal strategy can be applied for improving other 2D Sn‐based perovskites, thereby paving a new way to fabricate diverse 2D lead‐free perovskites with desirable PL properties. [ABSTRACT FROM AUTHOR]

Exciton localization is an approach for preparing highly luminescent semiconductors. However, realizing strongly localized excitonic recombination in low‐dimensional materials such as two‐dimensional (2D) perovskites remains challenging. Herein, we first propose a simple and efficient Sn2+ vacancy (VSn) tuning strategy to enhance excitonic localization in 2D (OA)2SnI4 (OA=octylammonium) perovskite nanosheets (PNSs), increasing their photoluminescence quantum yield (PLQY) to ≈64 %, which is among the highest values reported for tin iodide perovskites. Combining experimental with first‐principles calculation results, we confirm that the significantly increased PLQY of (OA)2SnI4 PNSs is primarily due to self‐trapped excitons with highly localized energy states induced by VSn. Moreover, this universal strategy can be applied for improving other 2D Sn‐based perovskites, thereby paving a new way to fabricate diverse 2D lead‐free perovskites with desirable PL properties. [ABSTRACT FROM AUTHOR]

There were increasing concerns on the possibility and suitability of using elevators for high-rise building evacuation because, through the improvement of the elevator system, the self-evacuation ability of age people is promoted as much as possible in the process of an emergency evacuation. The combined evacuation using both elevators and stairs was put into discussion. However, there was no empirical evidence and numerical simulation on emergency evacuation using both elevators and staircases for aging people in high-rise nursing homes. Therefore, using one case study, this paper simulated the emergency evacuation in a high-rise nursing home using variables such as the distribution of the elderly with different physical conditions, the proportion of the elderly in different physical conditions, the number of the elderly, the number of floors, the number of elevators used, and the priority of the elevator floor. By simulating the evacuation process in various scenarios, the general distribution strategy of high-rise nursing home and the optimal use of the elevator-stair combination during the emergency evacuation were developed. Results show that the elevator-stair combination of evacuation is more effective than using elevators or stairs alone. Increasing the number and speed of elevators can reduce evacuation time. Categorizing elderly people on each floor according to their physical conditions could reduce the evacuation time than randomly distributing them. [ABSTRACT FROM AUTHOR]

Inherent "soft" ionic lattice nature of halide perovskite quantum dots (QDs), triggered by the weak Pb−X (X=Cl, Br, I) bond, is recognized as the primary culprit for their serious instability. A promising way is to construct exceedingly strong ionic interaction inside the QDs and increase their crystal cohesive energy by substituting the interior X− with highly electronegative F−, however, which is challenging and hitherto remains unreported. Here, a "whole‐body" fluorination strategy is proposed for strengthening the interior bonding architecture of QDs, wherein the F− are uniformly distributed throughout the whole nanocrystal encompassing both the interior lattice and surface, successfully stabilizing their "soft" crystal lattice and passivating surface defects. This approach effectively mitigates their intrinsic instability issues including light‐induced phase segregation. As a result, light‐emitting devices based on these QDs exhibit exceptional efficiency and remarkable stability. [ABSTRACT FROM AUTHOR]

Inherent "soft" ionic lattice nature of halide perovskite quantum dots (QDs), triggered by the weak Pb−X (X=Cl, Br, I) bond, is recognized as the primary culprit for their serious instability. A promising way is to construct exceedingly strong ionic interaction inside the QDs and increase their crystal cohesive energy by substituting the interior X− with highly electronegative F−, however, which is challenging and hitherto remains unreported. Here, a "whole‐body" fluorination strategy is proposed for strengthening the interior bonding architecture of QDs, wherein the F− are uniformly distributed throughout the whole nanocrystal encompassing both the interior lattice and surface, successfully stabilizing their "soft" crystal lattice and passivating surface defects. This approach effectively mitigates their intrinsic instability issues including light‐induced phase segregation. As a result, light‐emitting devices based on these QDs exhibit exceptional efficiency and remarkable stability. [ABSTRACT FROM AUTHOR]

All‐inorganic α‐phase CsPbI3 perovskite with a suitable bandgap and superb optoelectronic properties is transforming the landscape of perovskite photovoltaics, but its long‐term lability associated with "soft" ionic lattice still imposes a great challenge for practical applications. Herein, a unique solid‐solution fluorination strategy is proposed to deliver an "ideal" perovskite matrix of α‐phase CsPbI3 abundant with F ions through interlocking the soft lattice of CsPbI3 with cubic‐phase CsF·3/2HF. Such a sublattice interlocking can not only stabilize the soft lattice of α‐phase CsPbI3 perovskite nanocrystals but also passivate their notorious surface defects, thereby producing a "rigid" solid‐solution‐type perovskite/fluoride CsPbI3/CsF (termed as CsPbI3:F) nanocomposite with excellent long‐term stability and a near‐unity photoluminescence efficiency. Of particular note is that these CsPbI3:F nanocomposites can work well as effective grain boundary anchors to significantly improve the photovoltaic performance of perovskite solar cells because of their F‐rich perovskite lattice, achieving a T80 stability of 1500 h under continuous maximum power point tracking and AM 1.5G illumination without the need for encapsulation. This work paves a new way to deliver perovskite materials with desirable properties for photovoltaics. [ABSTRACT FROM AUTHOR]

In this paper, we consider the complex dynamics of a novel mathematical model for a feedback control system of the gut microbiota, which was proposed by Dong, et al. The main work of the present paper is to study the effect of antibiotics injection on the gut microbiota through some dynamical methods, such as double Hopf bifurcation analysis and so on. We first use DDE-BIFTOOL to find the non-resonant double Hopf bifurcation points of the system, and draw the bifurcation diagram with two bifurcation parameters, τ 1 and τ 2 , i.e., respective measurement delays. Then we study small perturbations of two delay differential equations at these double Hopf bifurcation points, and the method of multiple scales is employed to obtain two common complex amplitude equations. By analyzing the amplitude equations, we can derive the classification and unfolding of these double Hopf bifurcation points. Finally, we verify the results by numerical simulations. We find more complicated dynamic behaviors of the system via analytical method. For example, there exists stable equilibrium, stable periodic solution or even the co-existing stable periodic solutions in respective region. And the numerical simulations are consistent with the analytic results, meanwhile it implies that the MMS is effective and accurate. All complex dynamical phenomena found in the present paper can be very helpful for the researchers to understand the mechanism of the system of gut microbiota. And it is also very significant to microbiology and engineering control. It reveals that the measurement delays can induce the complicated dynamics in this system and to the ends of excellent performance, we should take the proper values of these delays. • Find complicated behaviors in delayed gut microbiota system esp. bi-stability. • Measurement delays can induce complicated dynamics and careful to take values. • Complicated behaviors be very helpful to understand mechanism of gut mocrobiota. [ABSTRACT FROM AUTHOR]

Central Post-Stroke Pain (CPSP) is a primary sequelae of stroke that can develop in the body part corresponding to the cerebrovascular lesion after stroke, most typically after ischemic stroke but also after hemorrhagic stroke. The pathogenesis of CPSP is currently unknown, and research into its mechanism is ongoing. To summarize current research on the CPSP mechanism and provide guidance for future studies. Use "central post-stroke pain," "stroke AND thalamic pain," "stroke AND neuropathic pain," "post-stroke thalamic pain" as the search term. The search was conducted in the PubMed and China National Knowledge Infrastructure databases, summarizing and classifying the retrieved mechanism studies. The mechanistic studies on CPSP are extensive, and we categorized the included mechanistic studies and summarized them in terms of relevant pathway studies, relevant signals and receptors, relevant neural tissues, and described endoplasmic reticulum stress and other relevant studies, as well as summarized the mechanisms of acupuncture treatment. Studies have shown that the pathogenesis of CPSP involves the entire spinal-thalamo-cortical pathway and that multiple substances in the nervous system are involved in the formation and development of CPSP. Among them, the relevant receptors and signals are the hotspot of research, and the discovery and exploration of different receptors and signals have provided a wide range of therapeutic ideas for CPSP. As a very effective treatment, acupuncture is less studied regarding the analgesic mechanism of CPSP, and further experimental studies are still needed. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF) materials hold great promise as next‐generation efficient emitters due to their theoretical 100% internal quantum efficiency. However, such an intriguing photophysical mechanism is extremely rare in perovskites or their derivatives. Herein, the colloidal synthesis of two‐dimensional CsAgCl2 nanocrystals (NCs) with typical TADF feature is reported first. The TADF mechanism is investigated in detail by combining first‐principles calculations with experimental results, including temperature‐dependent spectral analysis and fs‐transient absorption spectra. A small singlet−triplet state splitting energy (0.082 eV) and a large spatial separation of charge density |Ψ|2 of valence band maximum and conduction band minimum are observed, which are prerequisites for TADF. Moreover, these CsAgCl2 NCs deliver an ultralow X‐ray detection limit of 170.5 nGyair s−1 and a high imaging resolution of 11.5 lp mm−1, much superior to the commercial scintillators. [ABSTRACT FROM AUTHOR]

All-inorganic Pb-free halide perovskites have recently received extensive attention due to their unique structures and optoelectronic properties. However, the realization of pure-blue emitting perovskite nanocrystals (NCs) with satisfactory stability and rational interpretation for their corresponding self-trapped excitons (STEs) emissions remains an arduous task. Herein, a modified hot-injection method is proposed to prepare a new family of zero-dimensional (0D) Cs 3 ZnX 5 (X = Cl, Br) perovskite NCs with pure-blue and sky-blue photoluminescence (PL) emissions. Benefitting from the 0D tetragonal-phase structure, the Cs 3 ZnX 5 NCs possess outstanding long-term stability in ambient air conditions. We employ the experimental results and first-principles calculations to confirm that the blue STEs emission of Cs 3 ZnX 5 NCs is dominated by the halide vacancies (V X) in [ZnX 4 ]2- tetrahedra. Our findings not only provide a simple and valid method to control the synthesis of blue-emitting 0D Zn-based perovskite NCs, but also clarify their underlying PL mechanism. • A new family of zero-dimensional Cs 3 ZnX 5 (X = Cl, Br) perovskite nanocrystals. • Perovskites with stable pure-blue and sky-blue photoluminescence emissions. • Self-trapped excitons luminescence induced by halide vacancies of perovskites. • A universal luminescence mechanism for zero-dimensional Zn-based halide perovskites. [ABSTRACT FROM AUTHOR]