Achieving Long-Lived Charge Separated State through Ultrafast Interfacial Hole Transfer in Redox Sites-Isolated CdS Nanorods for Enhanced Photocatalysis.

As opposed to natural photosynthesis, a significant challenge in a semiconductor-based photocatalyst is the limited hole extraction efficiency, which adversely affects solar-to-fuel efficiency. Recent studies have demonstrated that photocatalysts featuring spatially isolated dual catalytic oxidation/reduction sites can yield enhanced hole extraction efficiencies. However, the decay dynamics of excited states in such photocatalysts have not been explored. Here a ternary barbell-shaped CdS/MoS2/Cu2S heterostructure is prepared, comprising CdS nanorods (NRs) interfaced with MoS2 nanosheets at both ends and Cu2S nanoparticles on the sidewall. By using transient absorption (TA) spectra, highly efficient charge separation within the CdS/MoS2/Cu2S heterostructure are identified. This is achieved through directed electron transfer to the MoS2 tips at a rate constant of >8.3 × 109 s-1 and rapid hole transfer to the Cu2S nanoparticles on the sidewall at a rate of >6.1 × 1010 s-1, leading to an exceptional overall charge transfer constant of 2.3 × 1011 s-1 in CdS/MoS2/Cu2S. The enhanced hole transfer efficiency results in a remarkably prolonged charge-separated state, facilitating efficient electron accumulation within the MoS2 tips. Consequently, the ternary CdS/MoS2/Cu2S heterostructure demonstrates a 22-fold enhancement in visible-light-driven H2 generation compare to pure CdS nanorods. This work highlights the significance of efficient hole extraction in enhancing the solar-to-H2 performance of semiconductor-based heterostructure.

Efficient and stable emission of warm-white light from lead-free halide double perovskites.

Lighting accounts for one-fifth of global electricity consumption1. Single materials with efficient and stable white-light emission are ideal for lighting applications, but photon emission covering the entire visible spectrum is difficult to achieve using a single material. Metal halide perovskites have outstanding emission properties2,3; however, the best-performing materials of this type contain lead and have unsatisfactory stability. Here we report a lead-free double perovskite that exhibits efficient and stable white-light emission via self-trapped excitons that originate from the Jahn-Teller distortion of the AgCl6 octahedron in the excited state. By alloying sodium cations into Cs2AgInCl6, we break the dark transition (the inversion-symmetry-induced parity-forbidden transition) by manipulating the parity of the wavefunction of the self-trapped exciton and reduce the electronic dimensionality of the semiconductor4. This leads to an increase in photoluminescence efficiency by three orders of magnitude compared to pure Cs2AgInCl6. The optimally alloyed Cs2(Ag0.60Na0.40)InCl6 with 0.04 per cent bismuth doping emits warm-white light with 86 ± 5 per cent quantum efficiency and works for over 1,000 hours. We anticipate that these results will stimulate research on single-emitter-based white-light-emitting phosphors and diodes for next-generation lighting and display technologies.

Effect of irisin on the expression of osteoclast-related genes in cementoblasts.

BACKGROUND AND OBJECTIVES: Cementoblasts can communicate with osteoclasts by synthesis and secretion of cytokines, such as RANKL, OPG, and M-CSF. Previously, we reported that irisin promotes the differentiation of cementoblasts, while the effect of irisin on cementoblast-mediated osteoclastogenesis remains inconclusive. This study aimed to explore the effect of irisin on the expression of osteoclastogenesis-related cytokines in cementoblasts. MATERIAL AND METHODS: An immortalized murine cementoblast cell line OCCM-30 was used. Immunofluorescence and Western Blot were performed to identify the expression of irisin receptor integrin alphaV and the activation of its downstream signals in OCCM-30 cells. Cells were treated with irisin (100 ng/ml) for various time lengths ranging from 0 to 72 hours, and then qRT-PCR was used to detect the expression of osteoclastogenesis-related genes, including RANKL, IL-6, M-CSF, OPG, Wnt5A, Sema3A. Cells were also incubated with irisin in a series of concentrations (0-200 ng/ml) for 24 hours, and then qRT-PCR and ELISA were performed to examine the above osteoclastogenesis-related cytokines. RESULTS: Irisin receptor integrin alphaV was expressed in OCCM-30 cells and its downstream signaling pathways were markedly activated by irisin. Both qRT-PCR and ELISA results revealed that RANKL and IL-6 were up-regulated by irisin while M-CSF, OPG, Wnt5A, Sema3A remained unaffected. CONCLUSIONS: OCCM-30 cells were responsive to the stimulation of irisin. The expression of RANKL and IL-6 was significantly enhanced by irisin, suggesting a possible promotive effect on cementoblast-mediated osteoclastogenesis.

Kinetic Analysis of Transient Intermediates in the Mechanism of Prenyl-Flavin-Dependent Ferulic Acid Decarboxylase.

Ferulic acid decarboxylase catalyzes the decarboxylation of various substituted phenylacrylic acids to their corresponding styrene derivatives and CO2 using the recently discovered cofactor prenylated FMN (prFMN). The mechanism involves an unusual 1,3-dipolar cycloaddition reaction between prFMN and the substrate to generate a cycloadduct capable of undergoing decarboxylation. Using native mass spectrometry, we show the enzyme forms a stable prFMN-styrene cycloadduct that accumulates on the enzyme during turnover. Pre-steady state kinetic analysis of the reaction using ultraviolet-visible stopped-flow spectroscopy reveals a complex pattern of kinetic behavior, best described by a half-of-sites model involving negative cooperativity between the two subunits of the dimeric enzyme. For the reactive site, the cycloadduct of prFMN with phenylacylic acid is formed with a kapp of 131 s-1. This intermediate converts to the prFMN-styrene cycloadduct with a kapp of 75 s-1. Cycloelimination of the prFMN-styrene cycloadduct to generate styrene and free enzyme appears to determine kcat for the overall reaction, which is 11.3 s-1.

Ultrafast and High-Yield Polaronic Exciton Dissociation in Two-Dimensional Perovskites.

Layered two-dimensional (2D) lead halide perovskites are a class of quantum well (QW) materials, holding dramatic potentials for optical and optoelectronic applications. However, the thermally activated exciton dissociation into free carriers in 2D perovskites, a key property that determines their optoelectronic performance, was predicted to be weak due to large exciton binding energy (Eb, about 100-400 meV). Herein, in contrast to the theoretical prediction, we discover an ultrafast (<1.4 ps) and highly efficient (>80%) internal exciton dissociation in (PEA)2(MA)n-1PbnI3n+1 (PEA = C6H5C2H4NH3+, MA = CH3NH3+, n = 2-4) 2D perovskites despite the large Eb. We demonstrate that the exciton dissociation activity in 2D perovskites is significantly promoted because of the formation of exciton-polarons with considerably reduced exciton binding energy (down to a few tens of millielectronvolts) by the polaronic screening effect. This ultrafast and high-yield exciton dissociation limits the photoluminescence of 2D perovskites but on the other hand well explains their exceptional performance in photovoltaic devices. The finding should represent a common exciton property in the 2D hybrid perovskite family and provide a guideline for their rational applications in light emitting and photovoltaics.

Trap-Enabled Long-Distance Carrier Transport in Perovskite Quantum Wells.

Layered two-dimensional (2D) hybrid perovskites are naturally formed multiple quantum well (QW) materials with promising applications in quantum and optoelectronic devices. In principle, the transport of excitons in 2D perovskites is limited by their short lifetime and small mobility to a distance within a few hundred nanometers. Herein, we report an observation of long-distance carrier transport over 2 to 5 µm in 2D perovskites with various well thicknesses. Such a long transport distance is enabled by trap-induced exciton dissociation into long-lived and nonluminescent electron-hole separated state, followed by a trap-mediated charge transport process. This unique property makes 2D perovskites comparable with 3D perovskites and other traditional semiconductor QWs in terms of a carrier transport property and highlights their potential application as an efficient energy/charge-delivery material.

Excitation-Dependent Emission Color Tuning from an Individual Mn-Doped Perovskite Microcrystal.

Divalent manganese cation (Mn2+) doped perovskite materials are of great interest for their unique optical, magnetic, and electric properties. Herein, we report an excitation-dependent emission color tuning from an individual Mn-doped CsPbCl3 microcrystal (MC) with a wide color tuning range, reversible and continuous color change, and high photostability. We demonstrate that the Mn-doped CsPbCl3 MCs exhibit dual-color emission from both host excitons (blue) and Mn-dopants (orange) through an internal energy transfer (IET) process. By simple change of the laser excitation repetition rate or pulse intensity, the relative emission intensity between exciton (Iexciton) and Mn-dopant (IMn) can be continuously and reversibly tuned from IMn/Itotal (Itotal = IMn + Iexciton) = 0.9-0.8 to 0.1-0.2, corresponding to a color change from orange to blue. Such emission color tuning is enabled by the saturation of Mn-dopant emission at high excitation intensity and a linear dependence of exciton emission with excitation intensity. Transient spectroscopy and temperature-dependent photoluminescence (PL) measurements confirm that the exciton-to-dopant IET in Mn-doped CsPbCl3 MCs is mediated by some shallow trap states, rather than through a direct transfer pathway. Therefore, the saturation of Mn-dopant emission is caused by a bottlenecked energy transfer effect by saturating the mediating trap states at high excitation intensities. The Mn-doped MCs also exhibit a high photostability on the reversible switch of emission color between orange and blue for more than 300 cycles within a continuous operation time of 14 h. In view of the stable and color-switchable emission properties, Mn-doped perovskite MCs may find application in nanophotonic devices using a single MC.

Long-Distance Charge Carrier Funneling in Perovskite Nanowires Enabled by Built-in Halide Gradient.

The excellent charge carrier transportation in organolead halide perovskites is one major contributor to the high performance of many perovskite-based devices. There still exists a possibility for further enhancement of carrier transportation through nanoscale engineering, owing to the versatile wet-chemistry synthesis and processing of perovskites. Here we report the successful synthesis of bromide-gradient CH3NH3PbBrxI3-x single-crystalline nanowires (NWs) by a solid-to-solid ion exchange reaction starting from one end of pure CH3NH3PbI3 NWs, which was confirmed by local photoluminescence (PL) and energy dispersive X-ray spectroscopy (EDS) measurements. Due to the built-in halide gradient, the long-distance carrier transportation was driven by the energy funnel, rather than the spontaneous carrier diffusion. Indeed, local PL kinetics demonstrated effective charge carrier transportation only from the high-bandgap bromide-rich region to the low-bandgap iodine-rich region over a few micrometers. Therefore, these halide gradient NWs might find applications in various optoelectronic devices requiring long-distance and directional delivery of excitation energy.

Adhesion of Blood Clots Can Be Enhanced When Copolymerized with a Macromer That Is Crosslinked by Coagulation Factor XIIIa.

The adhesion of blood clots to blood vessels, such as through the adhesion of fibrin, is essential in hemostasis. While numerous strategies for initiating clot formation and preventing clot lysis are being developed to create improved hemostatic agents, strategies for enhancing clot adhesion have not been widely explored. Here, we show that adhesion of blood clots can be increased by adding a previously characterized synthetic polymer that is crosslinked by coagulation factor XIIIa during clotting. Addition of the polymer to normal plasma increased the adhesive strength of clots by 2-fold. It also recovered the adhesive strength of nonadhesive fibrinogen-deficient whole blood clots from <0.06 kPa to 1.9 ± 0.14 kPa, which is similar to the adhesive strength of a fibrinogen-rich clot (1.8 ± 0.64 kPa). The polymer also enabled plasma clots to remain adhered under fibrinolytic conditions. By demonstrating that the adhesive strength of clots can be increased with a synthetic material, this provides a potential strategy for creating advanced hemostatic materials, such as treatments for fibrinogen deficiency in trauma-induced coagulopathy.

Limiting Perovskite Solar Cell Performance by Heterogeneous Carrier Extraction.

Although the power conversion efficiency of perovskite solar cells has improved rapidly, a rational path for further improvement remains unclear. The effect of large morphological heterogeneity of polycrystalline perovskite films on their device performance by photoluminescence (PL) microscopy has now been studied. Contrary to the common belief on the deleterious effect of morphological heterogeneity on carrier lifetimes and diffusivities, in neat CH3 NH3 PbI3 (Cl) polycrystalline perovskite films, the local (intra-grain) carrier diffusivities in different grains are all surprisingly high (1.5 to 3.3 cm2 s-1 ; comparable to bulk single-crystals), and the local carrier lifetimes are long (ca. 200 ns) and surprisingly homogenous among grains, and uniform across grain boundary and interior. However, there is a large heterogeneity of carrier extraction efficiency at the perovskite grain-electrode interface. Improving homogeneity at perovskite grain-electrode contacts is thus a promising direction for improving the performance of perovskite thin-film solar cells.

Visualizing Carrier Diffusion in Individual Single-Crystal Organolead Halide Perovskite Nanowires and Nanoplates.

Single-crystal CH3NH3PbX3 (X = I(-), Cl(-), Br(-)) perovskite nanowires (NWs) and nanoplates (NPs), which demonstrate ultracompact sizes and exceptional photophysical properties, offer promises for applications in nanoscale photonics and optoelectronics. However, traditional electronic and transient techniques are limited by the dimensions of the samples, and characterizations of the carrier behavior (diffusion coefficient, charge mobility and diffusion length) in these NWs and NPs are extremely difficult. Herein, we report the direct visualization of the carrier diffusion process in individual single-crystal CH3NH3PbI3 and CH3NH3PbBr3 NWs and NPs using time-resolved and photoluminescence-scanned imaging microscopy. We report the diffusion coefficient (charge motility), which varies significantly between different NWs and NPs, ranging from 1.59 to 2.41 cm(2) s(-1) (56.4 to 93.9 cm(2) V(-1) s(-1)) for CH3NH3PbI3 and 0.50 to 1.44 cm(2) s(-1) (19.4 to 56.1 cm(2) V(-1) s(-1)) for CH3NH3PbBr3 and find this variation is independent of the shape and size of the sample. The average diffusion length is 14.0 ± 5.1 µm for CH3NH3PbI3 and 6.0 ± 1.6 µm for CH3NH3PbBr3. These results provide information that is essential for the practical applications of the single-crystal perovskite NWs and NPs, and the imaging microscopy may also be applicable to other optoelectronic materials.

In vitro selection of DNA aptamers for metastatic breast cancer cell recognition and tissue imaging.

Cancer is a major public health issue, with metastatic cancer accounting for the overwhelming majority of cancer deaths. Early diagnosis and appropriate treatment of metastatic cancer may largely prolong the survival rate and improve the quality of life for patients. In this study, we have identified a panel of DNA aptamers specifically binding to MDA-MB-231 cells derived from metastatic site-pleural effusion, with high affinity after 15 rounds of selections using the cell-based systematic evolution of ligands by exponential enrichment (SELEX) method. The selected aptamers were subjected to flow cytometry and laser confocal fluorescence microscopy to evaluate their binding affinity and selectivity. The aptamer LXL-1 with the highest abundance in the enriched library demonstrated a low K(d) value and excellent selectivity for the recognition of the metastatic breast cancer cells. Tissue imaging results showed that truncated aptamer sequence LXL-1-A was highly specific to the corresponding tumor tissue and displayed 76% detection rate against breast cancer tissue with metastasis in regional lymph nodes. Therefore, on the basis of its excellent targeting properties and functional versatility, LXL-1-A holds great potential to be used as a molecular imaging probe for the detection of breast cancer metastasis. Our result clearly demonstrates that metastatic-cell-based SELEX can be used to generate DNA ligands specifically recognizing metastatic cancer cells, which is of great significance for metastatic cancer diagnosis and treatment.

Facile Construction of a Double-Heterojunction Perovskite Quantum Dot System for Efficient Photocatalytic Cr6+ Reduction.

Based on their excellent stability, high carrier mobility, and wide photoresponse range, composites formed by embedding perovskite quantum dots (PQDs) into metal-organic frameworks (PQDs@MOF) show great development potential in the field of photocatalysis, including the toxic hexavalent chromium (Cr6+) degradation, CO2 reduction, H2 production, etc. However, the rapid recombination of photogenerated carriers is still a major obstacle to the improvement of photocatalytic performance, and the internal mechanism of photocatalysis is still unclear. In this work, we construct a novel double heterojunction photocatalyst by encapsulating CsPbBr3 PQDs in Zr-based metal-organic frameworks (UiO-67) and loading additional hole-acceptor pentylenetetrazol (PTZ). Spontaneous photoinduced charge-transfer and separation between interfaces are confirmed by time-resolved photoluminescence and transient absorption spectroscopy. Furthermore, compared with pure UiO-67, the photoactivity of CsPbBr3 PQDs@UiO-67@PTZ increased 3-fold due to the long-lived charge-separated state. Our findings provide a new guideline for the design of PQDs@MOF-based photocatalysts with long-lived photogenerated carriers and outstanding photocatalytic activity.

Traditional Chinese herbal formulas modulate gut microbiome and improve insomnia in patients with distinct syndrome types: insights from an interventional clinical study.

Background: Traditional Chinese medicine (TCM) comprising herbal formulas has been used for millennia to treat various diseases, such as insomnia, based on distinct syndrome types. Although TCM has been proposed to be effective in insomnia through gut microbiota modulation in animal models, human studies remain limited. Therefore, this study employs machine learning and integrative network techniques to elucidate the role of the gut microbiome in the efficacies of two TCM formulas - center-supplementing and qi-boosting decoction (CSQBD) and spleen-tonifying and yin heat-clearing decoction (STYHCD) - in treating insomnia patients diagnosed with spleen qi deficiency and spleen qi deficiency with stomach heat. Methods: Sixty-three insomnia patients with these two specific TCM syndromes were enrolled and treated with CSQBD or STYHCD for 4 weeks. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index (ISI) every 2 weeks. In addition, variations in gut microbiota were evaluated through 16S rRNA gene sequencing. Stress and inflammatory markers were measured pre- and post-treatment. Results: At baseline, patients exhibiting only spleen qi deficiency showed slightly lesser severe insomnia, lower IFN-α levels, and higher cortisol levels than those with spleen qi deficiency with stomach heat. Both TCM syndromes displayed distinct gut microbiome profiles despite baseline adjustment of PSQI, ISI, and IFN-α scores. The nested stratified 10-fold cross-validated random forest classifier showed that patients with spleen qi deficiency had a higher abundance of Bifidobacterium longum than those with spleen qi deficiency with stomach heat, negatively associated with plasma IFN-α concentration. Both CSQBD and STYHCD treatments significantly improved sleep quality within 2 weeks, which lasted throughout the study. Moreover, the gut microbiome and inflammatory markers were significantly altered post-treatment. The longitudinal integrative network analysis revealed interconnections between sleep quality, gut microbes, such as Phascolarctobacterium and Ruminococcaceae, and inflammatory markers. Conclusion: This study reveals distinct microbiome profiles associated with different TCM syndrome types and underscores the link between the gut microbiome and efficacies of Chinese herbal formulas in improving insomnia. These findings deepen our understanding of the gut-brain axis in relation to insomnia and pave the way for precision treatment approaches leveraging TCM herbal remedies.

Imaging the Moisture-Induced Degradation Process of 2D Organolead Halide Perovskites.

Two-dimensional (2D) and quasi-2D Ruddlesden-Popper (RP) phase organolead halide perovskites are promising materials for both photovoltaic and optoelectronic devices. Although they are known to be more stable when exposed to moisture than their 3D counterpart, chemical degradation of these materials under moisture, which not only leads to a significant drop in device performance but also leads to lead leakage, yet remains one of the most serious hurdles for their practical applications. To gain insight into the degradation mechanism of 2D/quasi-2D perovskites under moisture conditions, the degradation pathway of 2D/quasi-2D (PEA)2(MA) n-1PbnI3n+1 (PEA = C6H5C2H4NH3 +, MA = CH3NH3 +, and n is the number of perovskite layers between adjacent organic spacer layers) perovskite single crystals (SCs) and thin film are explored. We observe the degradation process by mapping the photoluminescence of the 2D perovskites and demonstrate that the larger-n phases all directly degrade into the relative stable n = 1 phase and MAI and PbI2, which is a mechanism different from that in previous reports and further confirmed in the 2D perovskite thin film. This degradation process is also found to be independent of the boundary and morphology of the SCs. This discovery provides a new perspective for understanding the chemical degradation of the 2D perovskite materials and may inspire new solutions for improving their moisture stability.

Interfering HMGB3 release from cancer-associated fibroblasts by miR-200b represses chemoresistance and epithelial-mesenchymal transition of gastric cancer cells.

Background: Cancer-associated fibroblasts (CAFs) are vital components of gastric cancer (GC) microenvironments, which impact the aggressive characteristics of GC cells. The objective of this study is to evaluate the influence of High Mobility Group Box (HMGB) on CAF-related GC. Methods: The tissues of 10 GC patients who underwent surgery the Sanya Central Hospital of Hainan Province from July 2018 to July 2019 were collected for the clinical study. Moreover, the GC cell lines, including MGC-803, AGS, and SGC-7901, were used in vitro experiment. We investigated the molecular mechanism of the miR-200b/HMGB3 axis in affecting the chemoresistance and epithelial-mesenchymal transition (EMT) of GC cells induced by CAFs. Cell transfection, Cell Counting Kit-8 (CCK-8), Transwell assay, western blot, enzyme-linked immunosorbent assay (ELISA), and other experiments were employed. Results: We found that miR-200b was down-regulated, yet HMGB3 was up-regulated in CAF-related GC. The CAFs markedly promoted cisplatin (CDDP) resistance, proliferation, invasion, migration, and EMT of GC cells. Gain-assay of miR-200b demonstrated that miR-200b inhibited the HMGB3 release from CAFs. In-vivo experiments confirmed that the growth and EMT of GC cells co-cultured with CAF-miR-200b were significantly reduced. Furthermore, CAFs enhanced the activation of ERK, JNK, and the Wnt/ß-catenin pathways, and those pathways, as well as the malignant behaviors of GC cells, were obviously attenuated by miR-200b or HMGB3 silencing. Conclusions: Collectively, HMGB3 derived from CAFs is negatively regulated by miR-200b and promotes the malignant behaviors of GC cells.

A Computationally Constructed lncRNA-Associated Competing Triplet Network in Clear Cell Renal Cell Carcinoma.

Long noncoding RNAs (lncRNAs) are revealed to be involved in the tumorigenesis and progression of human malignancies mediated by microRNA (miRNA) via the competing endogenous RNA (ceRNA) mechanism, a newly proposed "RNA language." However, the lncRNA-associated competing triplet (lncACT) network among ceRNA transcripts in clear cell renal cell carcinoma (ccRCC) is currently lacking. We carried out differential expression analysis to identify aberrantly expressed lncRNAs, miRNAs, and mRNAs by analyzing the RNA-seq data of 420 ccRCC tissues and 71 noncancerous kidney tissues obtained from The Cancer Genome Atlas (TCGA). Then, a ccRCC-specific ceRNA network was built using computational algorithms, including miRcode, TargetScan, miRanda, and miRTarBase. In total, 1491 dysregulated lncRNAs were found between normal renal tissues and ccRCC (fold change > 4 and false discovery rate < 0.01). A ceRNA network that comprised of 46 DElncRNAs, 11 DEmiRNAs, and 55 DEmRNAs was established by integrating the lncRNA/miRNA and miRNA/mRNA interactions into lncACTs. Several lncRNAs were identified to be significantly associated with clinical features of ccRCC patients. Notably, four key lncRNAs (TCL6, HOTTIP, HULC, and PCGEM1) were tightly correlated with both patients' clinical characteristics and overall survival (log-rank P < 0.05), indicating their potential important roles in ccRCC. HOTTIP may be a potential prognostic and therapeutic molecular marker for ccRCC patients. Collectively, our results provide a comprehensive view of the lncRNA-associated ceRNA regulatory network for a better understanding of the mechanisms and prognosis biomarkers for ccRCC.

A split Bregman method solving optimal reactive power dispatch for a doubly-fed induction generator-based wind farm.

This paper proposes an optimal reactive power control method to maximize wind farm revenue and minimize the total electrical losses of a doubly-fed induction generator (DFIG)-based wind farm. Specifically, the split Bregman method is used to solve the optimal control problem in a distributed manner. That is, the optimization problem is decomposed into sub-problems by the optimal distributed control strategy, and each sub-problem is solved independently in each local controller through the parallel method, which reduces the calculating burden and improves the information privacy. Thus, when a fault occurs, the proposed distributed control strategy can overcome the system fault and improve the reliability and security of the system. Furthermore, an economic financial model of annual revenue is contributed to examine the income impact with or without certified emission reduction (CER) by the clean development mechanism (CDM). Compared with the dual ascent (DA) method, sequential quadratic programming (SQP) method and the proportional dispatch method (PDM), the annual revenue (AR) of the wind farm using the proposed split Bregman method is the highest. Simulation results demonstrate that this method has promising performance in both optimization quality and computational efficiency.

Efficient External Energy Transfer from Mn-Doped Perovskite Nanocrystals.

Doping with a transition metal is an effective way to tune the optical properties of semiconductor nanocrystals (NCs). The excitation of transition-metal dopants in NCs is through an internal energy transfer from a host exciton, by which the short-lived exciton energy can be "stored" at the dopant for a significantly longer lifetime. Herein, using Mn-doped CsPbCl3 perovskite NCs as an example, we report that the long-lived excited state at Mn dopants can be efficiently extracted from the NCs through an external energy transfer (EET) to rhodamine B (RhB) molecules adsorbed on the NC surface. The EET process leads to a delayed RhB emission. The EET rate is found to increase from 0.16 to 1.42 ms-1 as the number of RhB molecules adsorbed per NC increases from 1 to 8.9, leading to energy extraction efficiency up to 71%. This work suggests the potential of Mn-doped perovskite NCs for applications in photon energy conversion and biological imaging.

Defect-Induced Inhomogeneous Phase Transition in 2D Perovskite Single Crystals at Low Temperatures.

The temperature-induced phase transition in two-dimensional (2D) layered perovskites was recently found to be incomplete even if the temperature dropped to tens of kelvin. However, its intrinsic cause still remains unclear, and the information on the phase transition in individual single crystals (SCs) is also limited. Herein, we study the phase transition process in individual (n-C4H9NH3)2PbI4 SCs using a home-built photoluminescence (PL)-scanned image microscope. At 83 K, the phase transition is indeed incomplete, leading to the coexistence and inhomogeneous distributions of room-temperature and low-temperature phases. We map the distribution of phase transition degree on individual SCs at 83 K, which exhibits a strong positive (negative) correlation with the distribution of local defects (PL lifetimes) at 293 K, indicating that the phase transition is enhanced by initial defects. Our findings might provide new insight into the phase transition of (n-C4H9NH3)2PbI4 crystals, which is of potential value for applications based on 2D layered perovskites.