Stable Bismuth-Doped Lead Halide Perovskite Core-Shell Nanocrystals by Surface Segregation Effect.

Lead halide perovskite nanocrystals (NCs) exhibit excellent optoelectronic performance, however, the broad application is limited by their poor stability. Herein, a strategy for stable core-shell structured bismuth-doped lead halide perovskite NCs is reported. The stable core-shell perovskite NCs are prepared based on heterovalent substitutions and surface segregation effect. Core-shell features are revealed through advanced characterization and structure analyses. Meanwhile, the transfer of carriers between the core and the shell is observed by ultrafast transient absorption spectroscopy. The core-shell structured perovskite NCs exhibit outstanding structure stability and retain 97% of the original photocatalytic efficiency after cycle experiments under moisture ambient and light irradiation. Such a core-shell structure constructs gradient energy levels. These findings are expected to facilitate the development of stable lead halide perovskite devices.

Percutaneous Transhepatic Papillary Balloon Dilation versus Endoscopic Retrograde Cholangiopancreatography for Common Bile Duct Stones: A Multicenter Prospective Study.

Background Endoscopic retrograde cholangiopancreatography (ERCP) is recommended by major guidelines for the removal of common bile duct (CBD) stones but is technically challenging in patients with low cardiopulmonary reserve and anatomic abnormalities of the upper gastrointestinal (GI) tract. Purpose To compare percutaneous transhepatic papillary balloon dilation (PTPBD) with ERCP for CBD stone removal. Materials and Methods Participants with one to three CBD stones (largest stone ≤30 mm) and without intrahepatic bile duct or gallbladder stones were eligible for this prospective cohort study. PTPBD was recommended in participants with low cardiopulmonary reserve or definitive anatomic abnormalities of the upper GI tract. Otherwise, both procedures were offered without preference. Follow-up, including abdominal CT, was conducted at 1-week and 1-, 3- and 6-month follow-up, and every 6 months thereafter. US and MR cholangiopancreatography were conducted if recurrence could not be confirmed with CT. Technical success rate was the primary outcome. Results A total of 531 participants were analyzed: there were 360 undergoing PTPBD (median age, 76 years; interquartile range [IQR], 64-82 years; 163 men) and 171 undergoing ERCP (median age, 66 years; IQR, 57-74 years; 94 men). The technical success rate was 99% (355 of 360) in the PTPBD group and 98% (167 of 171) in the ERCP group (relative risk, 1.02; P = .12). The incidence of overall complications was 4% (13 of 360) for PTPBD and 8% (13 of 171) for ERCP (relative risk, 0.27; 95% CI: 0.12, 0.61; P < .001). The PTPBD group showed a longer fluoroscopy time and a higher radiation exposure, with adjusted differences of 28.7 minutes (95% CI: 22.2, 35.2) and 384.3 mGy (95% CI: 296.5, 472), respectively. A propensity score-matching analysis (n = 123 per group) indicated that PTPBD had a slightly higher technical success rate and significantly fewer complications. Conclusion When compared with endoscopic retrograde cholangiopancreatography, percutaneous transhepatic papillary balloon dilation has a similar technical success rate and fewer perioperative complications but a higher radiation exposure. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by van Sonnenberg and Mueller in this issue.

Synthesis of monodisperse water-stable surface Pb-rich CsPbCl3 nanocrystals for efficient photocatalytic CO2 reduction.

Surface Pb-rich lead halide (CsPbCl3) perovskite nanocrystals (NCs) with high stability and monodispersity in water have been synthesized using a general and convenient liquid-solid interpenetration (LSI) method. In this process, water molecules permeate into the solid CsPbCl3 NC layers and slowly dissolve the Cs+ and Cl- ions on the surface of CsPbCl3 NCs. The Cs+ and Cl- ions in water inhibit the decomposition rate of CsPbCl3 NCs, inducing surface Pb-rich layers. The surface Pb-rich structure increases the photoluminescence (PL) lifetimes and improves the photocatalytic performances of lead halide perovskite NCs. Under simulated solar irradiation, the largest rate of CO2 photoreduction from surface Pb-rich Ni-doped CsPbCl3 NCs reaches up to 169.37 µmol g-1 h-1. This study provides an effective general strategy to design stable lead halide perovskite quantum dots (QDs) for their wide applications.

Effective Singlet Oxygen Generation in Silica-Coated CsPbBr3 Quantum Dots through Energy Transfer for Photocatalysis.

Here, silica-coated CsPbBr3 quantum dots (QDs) were demonstrated to be effective photosensitizers for the generation of singlet oxygen (1 O2 ). The silica encapsulation improved the stability of the perovskite QDs while also preserving an excellent light-harvesting capability in the visible-light region. The appropriate exciton binding energy and dark exciton generation characteristics of perovskite QDs may be responsible for the energy transfer. The high oxidizability of 1 O2 makes the material attractive for application in decomposition of organic dyes such as methyl orange. This work provides new insight for designing excellent perovskite-based photocatalysts.

Highly stable CsPbBr3@SiO2 nanocomposites prepared via confined condensation for use as a luminescent ink.

We have firstly prepared CsPbBr3@SiO2 nanocomposites with a spherical morphology and diameters less than 125 nm via confined condensation into polystyrene. The obtained CsPbBr3@SiO2 exhibits high stability in polar solvents and can be used as a solution-processable luminescent ink.

Brachytherapy with iodine 125 seeds for bone metastases.

OBJECTIVE: To evaluate the treatment safety and efficacy of iodine 125 (I125) seeds implantation in patients with bone metastases and assess the availability of quality of life (QOL) as an index for efficacy evaluation. PATIENTS AND METHODS: The study enrolled 98 patients with 133 bone metastases from July 2010 to January 2016, who had undergone computed tomography-guided brachytherapy with I125 seeds. Brief pain inventory was administered to assess the degree of pain at the preoperative (W0) and postoperative 2 weeks, 4 weeks, 8 weeks, 12 weeks, and 24 weeks (W2, W4, W8, W12, and W24). Drug use, QOL score, and complications were also assessed. RESULTS: Postoperative pain scores were significantly decreased and maintained for a long term. Numerical rating scale score at W0 was 7.3 ± 1.6, which was decreased to 4.5 ± 1.7 (P < 0.01), 3.7 ± 1.3 (P < 0.01), 2.5 ± 1.1 (P < 0.01), 1.9 ± 0.9 (P < 0.01), and 1.3 ± 0.5 (P < 0.01) at W2, W4, W8, W12, and W24, respectively. After standardized transformation, the dose of morphine for patients at W0 was 175.2 ± 24.5 mg, which was decreased to 91.2 ± 21.7 mg (P < 0.01), 89.4 ± 24.6 mg (P < 0.01), 89.4 ± 24.6 mg (P < 0.01), 72.8 ± 14.8 mg (P < 0.01), and 56.7 ± 11.3 mg (P < 0.01) at W2, W4, W8, W12, and W24, respectively. The efficiency reached 65.3%, 85.1%, 91.2%, 95.2%, and 92.7% at postoperative W2, W4, W8, W12, and W24, respectively. QOL score at W0 was 17.4 ± 3.3, which increased to 23.2 ± 4.5 (P < 0.01), 28.6 ± 7.6 (P < 0.01), 43.2 ± 9.1 (P < 0.01), 45.6 ± 10.3 (P < 0.01), and 47.6 ± 9.8 (P < 0.01) at W2, W4, W8, W12, and W24, respectively. CONCLUSION: Brachytherapy with I125 seeds was safe and effective for treating bone metastases, offering a potential alternative to external-beam radiotherapy. QOL could be applied to evaluate the efficacy of I125 seeds implantation for treating bone metastases.

Atomically dispersed Au catalysts supported on CeO2 foam: controllable synthesis and CO oxidation reaction mechanism.

CO oxidation is a typical heterogeneous catalytic reaction. Development of active and stable low-temperature CO oxidation catalysts has been one of the hot topics in the field of catalysis. In this work, we explored the catalytic application of a series of Au catalysts supported on CeO2 foam using a modified deposition-precipitation method for CO oxidation. Among them, the catalyst with 1.1% Au loading content showed the highest catalytic activity, leading to the CO total conversion at 20 °C. Based on the strategy of stepwise reduction of Au loading content, we finally obtained the atomically monodisperse Au/CeO2 catalyst with high stability and strong resistance to elevated temperature, on which in situ DRIFTS analysis and DFT study were further performed to study the possible reactive site. Our results implied that the Au atoms on the CeO2 foam are the more stable sites for CO adsorption on the catalysts.

Room-Temperature Synthesis of Mn-Doped Cesium Lead Halide Quantum Dots with High Mn Substitution Ratio.

Here we report the room-temperature, atmospheric synthesis of Mn-doped cesium lead halide (CsPbX3) perovskite quantum dots (QDs). The synthesis is performed without any sort of protection, and the dual-color emission mechanism is revealed by density functional theory. The Mn concentration reaches a maximum atomic percentage of 37.73 at%, which is significantly higher in comparison to those achieved in earlier reports via high temperature hot injection method. The optical properties of as-prepared nanocrystals (NCs) remain consistent even after several months. Therefore, red-orange LEDs were fabricated by coating the composite of PS and as-prepared QDs onto ultraviolet LED chips. Additionally, the present approach may open up new methods for doping other ions in CsPbX3 QDs under room temperature, the capability of which is essential for applications such as memristors and other devices.

Perovskite quantum dots encapsulated in electrospun fiber membranes as multifunctional supersensitive sensors for biomolecules, metal ions and pH.

CsPbBr3 perovskite quantum dots (CPBQDs) have exhibited excellent optical properties, which implies their potential as an appealing candidate for fluorescence resonance energy transfer (FRET) based detection. In this work, in order to enhance the subsurface concentration of CPBQDs, which is important for the efficiency of FRET detection, a nanoscale polymethyl methacrylate (PMMA) fiber membrane (d≈ 400 nm) encapsulated with CPBQDs (CPBQDs/PMMA FM) is fabricated using an electrospinning method. The CPBQD/PMMA FM possesses comparable optical properties to CPBQDs, high quantum yields (88%) and a narrow half-peak width (∼14 nm). The sensing of trypsin is realized via the cleavage of peptide CF6 (Cys-Pro-Arg-Gly-R6G) and an extremely low detection limit of 0.1 µg mL-1 has been reached. Besides, owing to the high efficiency FRET process between the CPBQD/PMMA FM and cyclam-Cu2+, an unprecedented detection limit of Cu2+ has been pushed to 10-15 M. Furthermore, the pH value can be confirmed by the membrane in 10 ppb hydrazide R6G ethanol solution. The excellent optical characteristics of CPBQDs, high CPBQD subsurface concentration of the CPBQD/PMMA FM and robust durability of the PMMA coating all contribute to the outstanding sensitivity and stable detection performance of the CPBQD/PMMA FM.

CsPbBr3 Perovskite Quantum Dots-Based Monolithic Electrospun Fiber Membrane as an Ultrastable and Ultrasensitive Fluorescent Sensor in Aqueous Medium.

Perovskite quantum dots with excellent optical properties and robust durability stand as an appealing and desirable candidate for fluorescence resonance energy transfer (FRET) based fluorescence detection, a powerful technique featuring excellent accuracy and convenience. In this work, a monolithic superhydrophobic polystyrene fiber membrane with CsPbBr3 perovskite quantum dots encapsulated within (CPBQDs/PS FM) was prepared via one-step electrospinning. Coupling CPBQDs with PS matrix, this CPBQDs/PS FM composite exhibits high quantum yields (∼91%), narrow half-peak width (∼16 nm), nearly 100% fluorescence retention after being exposed to water for 10 days and 79.80% fluorescence retention after 365 nm UV-light (1 mW/cm2) illumination for 60 h. Thanks to the outstanding optical property of CPBQDs, an ultralow detection limit of 0.01 ppm was obtained for Rhodamine 6G (R6G) detection, with the FRET efficiency calculated to be 18.80% in 1 ppm R6G aqueous solution. Electrospun as well-designed fiber membranes, CPBQDs/PS FM composite also possesses good tailorability and recyclability, showing exciting potential for future implementation into practical applications.