Search

Stimuli‐responsive luminescent materials have attracted much research attention due to their wide application potential in various fields. Typically, the family of hydrated double perovskite A2MIIIX5·H2O shows unique emission color transformation between hydrated and dehydrated complexes, highlighting the application potential in advanced anti‐counterfeiting. Herein, two zero‐dimensional perovskites of Cs2YbCl5·H2O and Cs3YbCl6, are reported and broad‐band self‐trapped exciton recombination emission can be realized via external Sb3+ doping. Intriguingly, the Cs2YbCl5·H2O can be transformed to the dehydrated counterpart of Cs3YbCl6 through a facile methanol treatment at room temperature, leading to the emission color transformation from yellow to green. Notably, the green‐emissive Cs3YbCl6:Sb3+ delivers a high photoluminescence quantum yield of 67.3%. Leveraging the advantages of obvious methanol‐induced emission color transformation between Cs2YbCl5·H2O and Cs3YbCl6 at room temperature, Cs2YbCl5·H2O can be used in the field of high‐security‐level anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

The analytical solution of the steady-state seepage field of a circular cofferdam in nonhomogeneous layered soil of finite depth is derived, including the head function, exit hydraulic gradient formula, and seepage flow formula. The head function is obtained by dividing the circular cofferdam seepage field into regions and then using the separated variable method combined with the Sturm–Liouville theory, and the unknown coefficients in the head function are determined by constructing a system of equations through the integral transformation of the Bessel function. Based on the head function, an analytical equation is also given for the exit hydraulic gradient and seepage flow. The accuracy of the proposed analytical solution is verified by a comparison with numerical results as well as with the results of other methods. The proposed analytical solution is a display analytical solution without singularities and can be used as an effective tool for the analysis of circular cofferdam seepage problems. [ABSTRACT FROM AUTHOR]

The development of large‐area transparent organic‐inorganic hybrid metal halide (OIMH) scintillation screens is restricted by the anisotropic single‐crystal growth, numerous grain boundaries in polycrystalline wafers, and inhomogeneous dispersion in perovskite‐polymer composite films. The crystal‐glass phase transition of OIMH materials may provide a promising solution for the above significant challenges. Herein, a new class of transparent amorphous guanidinium‐based manganese bromide glasses, (DPG)2MnBr4 and (DOTG)2MnBr4 (DPG = 1,3‐diphenylguanidinium, DOTG = 1,3‐di‐o‐tolylguanidinium), are synthesized through a low‐temperature melt‐quenching process. The (DOTG)2MnBr4 shows impressive glass‐forming ability because of large viscosity (η) at the melting temperature (Tm) (η(Tm) = 3426 mPa·s) and small fragility index (m = 52.35), which can be a potential glass scintillator. The large‐area (e.g., 13 cm × 13 cm) transparent amorphous (DOTG)2MnBr4 glass scintillator shows high light transmittance of > 80%, a low detection limit of 237.3 nGy s−1 and high X‐ray imaging spatial resolution of 12 lp mm−1. Interestingly, the glass transition temperature of < 40 °C gives (DOTG)2MnBr4 glass unique thermoplastic properties, allowing it to conform to irregularly shaped objects and reduce the distortion in X‐ray imaging. [ABSTRACT FROM AUTHOR]

The current mainstream planar X‐ray imaging techniques face significant challenges for accurately capturing the internal structure of curved objects, since the variable distances between the curved objects and the flat‐panel scintillation screen cannot eliminate the distortion in X‐ray imaging. Though large‐area and transparent curved scintillation screens are much more desirable. Here, organic–inorganic hybrid Mn‐based single crystals ([CH3Ph3P]2MnX4, X = Cl, Br, I) exhibiting high photoluminescence quantum yield (PLQY) and low melting temperature have been employed to prepare transparent glass for X‐ray scintillation imaging application through a low‐temperature melting strategy. The [CH3Ph3P]2MnBr4‐glass shows high PLQY (47.8%), high‐resolution X‐ray imaging performance (12.3 lp mm−1), low limit of detection (25.33 nGy s−1), and impressive X‐ray irradiation stability (102 Gy). Furthermore, high‐contrast X‐ray imaging at a low dose (6.865 µGy per exposure, 14.5 times lower than the chest radiograph) is achieved. Based on the low glass transition temperature (Tg = 53.6 °C) and easy‐shapeable properties of [CH3Ph3P]2MnBr4‐glass scintillator, the large‐area curved scintillation screen with a series of sizes of Φ 2×4 – Φ 8×4 cm2 can be easily fabricated and show high X‐ray imaging quality. These findings provide a paradigm for future research in shapeable X‐ray scintillators, unlocking new possibilities for curved and 3D X‐ray imaging. [ABSTRACT FROM AUTHOR]

Single‐source white‐light emitters are highlighted with stable color and excellent color rendering ability, which can largely simplify the white‐light‐emitting‐diode (WLED) structure. All‐inorganic and lead‐free double perovskites have attracted extensive research interest and provide versatile doping sites to accommodate the extrinsic multi‐valent ions. Herein, the synthesis and tunable emission of Sb3+–Ln3+‐codoped Cs2NaYCl6 single crystals (SCs) is reported. Particularly, bright white‐light emission with a high photoluminescence quantum yield of 80.5% is yielded in 0.5%Sb3+–2%Tb3+–2%Sm3+‐codoped Cs2NaYCl6 SCs. Steady‐state photoluminescence (PL) and time‐resolved PL spectra are employed to reveal the energy transfer from Sb3+‐induced self‐trapped excitons to Ln3+ ions. Temperature‐dependent PL spectra further demonstrate that the fluorescence intensity ratio of band 657 to band 590 nm is highly dependent on the temperature, and the relative sensitivity reaches a maximum of up to 1.59% K−1 at 260 K. Moreover, the WLED based on 0.5%Sb3+‐2%Tb3+‐2%Sm3+‐codoped Cs2NaYCl6 SCs delivers a higher average color rendering index of 87 than 0.5%Sb3+‐0.8%Tb3+‐2.5%Ho3+‐codoped Cs2NaYCl6 (74.6). The outstanding white‐light‐emission performance together with the high temperature dependence of the fluorescence spectra confers Sb3+–Ln3+‐codoped Cs2NaYCl6 with huge application potential in solid‐state lighting and ratiometric optical thermometry. [ABSTRACT FROM AUTHOR]

There are many morphometric studies on Chiari malformation type I (CMI) patients, most of which focus on the posterior cranial fossa (PCF). Less attention has been paid to the atlanto-occipital joint. In this study, we aim to evaluate the morphological characteristics of the atlanto-occipital joint in CMI patients. The cervical CT imaging data of adult patients diagnosed with CMI but without any bony malformation in craniovertebral junction (CVJ) who were treated by the authors between January 2014 and December 2019 were retrospectively analyzed. The equal number of sex and age-matched healthy individuals were included as the control group. The morphometric analysis was performed by measuring the length and depth of the atlanto-occipital joint, and the depth/length ratio was calculated to evaluate the curvature of the joint. A total of 47 patients (15 males and 32 females) were included. The mean age of patients was 47.49 ± 9.01 years (range 19–62 years). The mean depth/length ratio of the atlanto-occipital joint in CMI patients was 0.141 ± 0.065 (range 0.027 − 0.274), which was smaller than that of control individuals (0.228 ± 0.057, range 0.069 − 0.379). And the difference was statistically significant (p <.01). The atlanto-occipital joints in CMI patients are significantly flatter compared with those in healthy controls. This morphological variation could lead to differences of the atlanto-occipital stability between CMI patients and normal population, which may be related to the pathogenesis of CMI. [ABSTRACT FROM AUTHOR]

Thermally activated delayed fluorescence (TADF) behaviors in metal halide perovskite and perovskite derivatives are rarely reported due to the absence of suitable TADF molecules that can serve as the A‐site cations. Herein, a series of novel donor‐π‐acceptor type of molecules are developed by adopting substituted phosphine and phosphonium as the electron donor and acceptor linked by the polarized π‐spacer. The prepared ((diphenylphosphaneyl)phenyl)diphenylphosphonium‐X (BzDPP‐X, X = counterions: Cl−, Br−, I−, NO3−, CH3COO− etc.) salts show bright emission in the visible range with TADF characteristics due to the strong intramolecular charge transfer (ICT). Benefiting from the spatially separated highest occupied molecular orbital and lowest unoccupied molecular orbital, small singlet‐triplet energy splitting (ΔEST) is obtained, facilitating the reverse intersystem crossing process. It turns out that the emission of BzDPP‐X is dependent on the counter anions, and the counterions help to stabilize the ICT state. Intriguingly, the emission can be tuned by integrating metal‐halide units into the above phosphonium salt. Remarkably, the zinc‐based halide exhibits a higher photoluminescence quantum yield (36.2%) than the pure benzyl(2‐(diphenylphosphaneyl)phenyl)diphenylphosphonium bromide (26.9%). This work exemplifies an easy design concept and a facile synthetic method toward ionic luminescent materials. [ABSTRACT FROM AUTHOR]

As the key component of a hydroelectric power generation system, hydraulic turbine plays a decisive role in the overall performance of the system. There are many sandy rivers in the world, and turbines working in these rivers are seriously damaged. Therefore, the research of flow in sandy water has great theoretical significance and practical value. Based on the specific hydrological conditions of a hydropower station, the solid–liquid two-phase flow in the whole flow passage of a Francis turbine with splitter blades in sandy water was numerically studied. A geometric model of the whole flow passage of the Francis turbine was established on the basis of given design parameters. The solid–liquid two-phase turbulent flows in Francis turbine runner under three different loads were numerically analyzed by using this model. The three different loads are as follows: Condition 1: single unit with 1/4 load, Condition 2: single unit with 1/2 load, and Condition 3: single unit with full load. The distributions of pressure and sand concentration on the leading side and the suction side of the runner blades, as well as the velocity vector distribution of water and sand on the horizontal section of the runner, were obtained under different load conditions. Therefore, the damages to various flow passage components by sand can be qualitatively predicated under various conditions. To guarantee the safety and stability of the unit, the adverse conditions shall be avoided, which can provide certain reference for plant operation.

Background: To investigate the perioperative peripheral blood levels of CD4+CD25+ regulatory T cells, programed cell death 1 (PD-1), and lymphocyte activation gene 3 (LAG-3) in patients with advanced Siewert type II adenocarcinoma of esophagogastric junction (AEG). Methods: Patients (n = 102) with advanced Siewert type II AEG underwent open total gastrectomy/proximal gastrectomy with a transhiatal resection of the distal esophagus and lymphadenectomy of the lower mediastinum and the abdominal D2 compartment. Flow cytometry was used to detect CD4+CD25+ T cells, PD-1 and LAG-3 expression on both CD4+ and CD8+ T cells in the peripheral blood of the Siewert type II AEG patients prior to surgery and on postoperative day (POD) 1, 3, 7, and 9. Results: The proportion of CD4+CD25+ T cells rapidly decreased on POD 1, then gradually increased and peaked at POD 7. The proportion of CD4+PD-1+ T cells significantly increased after surgery, reaching a maximum on POD 1, and remained significantly elevated on POD 3 compared to the preoperative day. The proportion of CD8+ PD-1+ and CD4+LAG-3+ T cells gradually increased after surgery and reached a peak at POD 7. The change in proportion of CD8+LAG-3+ T cells in the peripheral venous blood lymphocytes after surgery was not statistically significant. Conclusion: The change in the CD4+PD-1+ T lymphocyte ratio may likely reflect the cellular immunity status of the perioperative period. [ABSTRACT FROM AUTHOR]