The aggregation‐induced electrochemiluminescence (AIECL) of carboranyl carbazoles in aqueous media was investigated for the first time. Quantum yields, morphologies, and particle sizes were observed ...to determine the electrochemiluminescence (ECL) performance of these aggregated organic dots (ODs). All compounds exhibit much higher ECL stability and intensity than the carborane‐free compound, demonstrating the essential role of the carboranyl motif. Moreover, the results of cyclic voltammetry (CV) suggest that oxidation/reduction reactions take place at the carboranyl motif. The excited states of ODs were proposed to be generated by the mechanism of surface state transitions. More importantly, these compounds show a reductive–oxidative mechanism in contrast to other organic materials that show oxidative–reductive mechanisms. Our experiments and data have established the relation between AIE organic structures and ECL properties that has a strong potential for biological and diagnostic applications.
Carborane‐based AIEgens: The reductive–oxidative aggregation‐induced electrochemiluminescence (AIECL) of carboranyl carbazoles in air‐saturated aqueous media was investigated. Mechanistic studies indicate that the carboranyl motif plays vital role in the high ECL intensity and stability of the aggregates.
Androgens are functionally required for the normal growth of the prostate gland and in prostate tumor development and progression. Epithelial-mesenchymal-transition (EMT) is an important process ...during normal development and in cancer cell metastasis induced by factors within the microenvironment, such as transforming growth factor-β (TGF-β). This study examined the ability of androgens to influence EMT of prostate cancer epithelial cells. The EMT pattern was evaluated on the basis of expression of the epithelial markers E-cadherin/β-catenin, and the mesenchymal markers N-cadherin, as well as cytoskeleton reorganization in response to 5α-dihydrotestosterone (DHT; 1 nM) and/or TGF-β (5 ng/ml). Overexpressing and silencing approaches to regulate androgen receptor (AR) expression were conducted to determine the involvement of AR in EMT in the presence or absence of an AR antagonist. Our results demonstrate that androgens induce the EMT pattern in prostate tumor epithelial cell with Snail activation and lead to significant changes in prostate cancer cell migration and invasion potential. Expression levels of AR inversely correlated with androgen-mediated EMT in prostate tumor epithelial cells, pointing to a low AR content required for the EMT phenotype. These findings indicate the ability of androgens to induce EMT by potentially bypassing the functional involvement of TGF-β, thus contributing to metastatic behavior of prostate cancer cells.--Zhum, M.-L., Kyprianou, N. Role of androgens and the androgen receptor in epithelial-mesenchymal transition and invasion of prostate cancer cells.
The emergence of the rising alliance between aggregation‐induced emission (AIE) and electrochemiluminescence (ECL) is defined as aggregation‐induced electrochemiluminescence (AIECL). The booming ...science of AIE has proved to be not only distinguished in luminescent materials but could also inject new possibility into ECL analysis. Especially in the aqueous phase and solid state for hydrophobic materials, AIE helps ECL circumvent the dilemma between substantial emission intensity and biocompatible media. The wide range of analytes makes ECL an overwhelmingly interesting analytical technique. Therefore, AIECL has gained potential in clinical diagnostics, environmental assays, and biomarker detections. This review will focus on introduction of the novel concept of AIECL, current applied luminophores, and related applications developed in recent years.
Coupling AIE and ECL: This Minireview highlights the recent advances in principles, mechanisms, luminophore structures, and applications of aggregation‐induced electrochemiluminescence (AIECL) in order to promote rapid development of this area.
Electrochemical CO2 reduction reaction (CO2RR) is a promising approach to convert CO2 to carbon‐neutral fuels using external electric powers. Here, the Bi2S3‐Bi2O3 nanosheets possessing substantial ...interface being exposed between the connection of Bi2S3 and Bi2O3 are prepared and subsequently demonstrate to improve CO2RR performance. The electrocatalyst shows formate Faradaic efficiency (FE) of over 90% in a wide potential window. A high partial current density of about 200 mA cm−2 at −1.1 V and an ultralow onset potential with formate FE of 90% are achieved in a flow cell. The excellent electrocatalytic activity is attributed to the fast‐interfacial charge transfer induced by the electronic interaction at the interface, the increased number of active sites, and the improved CO2 adsorption ability. These collectively contribute to the faster reaction kinetics and improved selectivity and consequently, guarantee the superb CO2RR performance. This study provides an appealing strategy for the rational design of electrocatalysts to enhance catalytic performance by improving the charge transfer ability through constructing a functional heterostructure, which enables interface engineering toward more efficient CO2RR.
The heterostructured Bi2S3‐Bi2O3 nanosheets with substantial amount of interface are designed, which demonstrate the enhanced CO2 electroreduction performance. The fast‐interfacial charge transfer induced by the electronic interaction at the interface, together with the increased number of active sites and the improved CO2 adsorption ability, collectively contribute to the improved electrocatalytic performance.
The Chang'E‐3 lunar penetrating radar (LPR) observations at 500 MHz reveal four major stratigraphic zones from the surface to a depth of ~20 m along the survey line: a layered reworked zone (<1 m), ...an ejecta layer (~2–6 m), a paleoregolith layer (~4–11 m), and the underlying mare basalts. The reworked zone has two to five distinct layers and consists of surface regolith. The paleoregolith buried by the ejecta from a 500 m crater is relatively homogenous and contains only a few rocks. Population of buried rocks increases with depth to ~2 m at first, and then decreases with depth, representing a balance between initial deposition of the ejecta and later turnover of the regolith. Combining with the surface age, the LPR observations indicate a mean accumulation rate of about 5–10 m/Gyr for the surface regolith, which is at least 4–8 times larger than previous estimation.
Key Points
Chang'E‐3 high‐frequency lunar penetrating radar observations are presented
Four major stratigraphic zones at the Chang'E‐3 landing site are observed
Regolith accumulation rate is at least 4–8 times higher than previous estimation
As the largest container and resource of metals, sediment has a special role in the fate of metals. Factors influencing bioavailability of heavy metals in sediment have never been comprehensively ...considered and the sediment properties still fail to understand and even controversial. In this review, the mechanisms of sediment properties such as acid-volatile sulfides (AVS), organic matter, texture (clay, silt or sand) and geology, organism behaviors as well as those influencing the bioavailability of metals were analyzed. Under anoxic condition, AVS mainly reduce the solubility and toxicity of metals, while organic matters, Fe–Mn oxides, clay or silt can stabilize heavy metals in elevated oxidative–reductive potential (ORP). Other factors including the variation of pH, redox potential, aging as well as nutrition and the behavior of benthic organism in sediment also largely alter metals mobility and distribution. These factors are often inter-related, and various toxicity assessment methods used to evaluate the bioavailability of trace metals have been also discussed. Additionally, we expect that some novel synthetic materials like polysulfides, nano-materials, provide the substantial amendments for metals pollution in sediment.
•The influencing mechanisms of sediment geochemical properties on heavy metals bioavailability were analyzed.•AVS stabilize heavy metals in anoxic state but OM and Fe-Mn oxides immobilize metals under aerobic condition.•Considering the sediment geochemical properties is needed when establish the model of bioavailability.
Quantum anomalous Hall goes intrinsicQuantum anomalous Hall effect—the appearance of quantized Hall conductance at zero magnetic field—has been observed in thin films of the topological insulator ...Bi2Se3 doped with magnetic atoms. The doping, however, introduces inhomogeneity, reducing the temperature at which the effect occurs. Two groups have now observed quantum anomalous Hall effect in intrinsically magnetic materials (see the Perspective by Wakefield and Checkelsky). Serlin et al. did so in twisted bilayer graphene aligned to hexagonal boron nitride, where the effect enabled the switching of magnetization with tiny currents. In a complementary work, Deng et al. observed quantum anomalous Hall effect in the antiferromagnetic layered topological insulator MnBi2Te4.Science, this issue p. 900, p. 895; see also p. 848In a magnetic topological insulator, nontrivial band topology combines with magnetic order to produce exotic states of matter, such as quantum anomalous Hall (QAH) insulators and axion insulators. In this work, we probe quantum transport in MnBi2Te4 thin flakes—a topological insulator with intrinsic magnetic order. In this layered van der Waals crystal, the ferromagnetic layers couple antiparallel to each other; atomically thin MnBi2Te4, however, becomes ferromagnetic when the sample has an odd number of septuple layers. We observe a zero-field QAH effect in a five–septuple-layer specimen at 1.4 kelvin, and an external magnetic field further raises the quantization temperature to 6.5 kelvin by aligning all layers ferromagnetically. The results establish MnBi2Te4 as an ideal arena for further exploring various topological phenomena with a spontaneously broken time-reversal symmetry.
Noble metal nanoparticles are promising catalysts in electrochemical reactions, while understanding the relationship between the structure and reactivity of the particles is important to achieve ...higher efficiency of electrocatalysis, and promote the development of single‐molecule electrochemistry. Electrogenerated chemiluminescence (ECL) was employed to image the catalytic oxidation of luminophore at single Au, Pt, and Au‐Pt Janus nanoparticles. Compared to the monometal nanoparticles, the Janus particle structure exhibited enhanced ECL intensity and stability, indicating better catalytic efficiency. On the basis of the experimental results and digital simulation, it was concluded that a concentration difference arose at the asymmetric bimetallic interface according to different heterogeneous electron‐transfer rate constants at Au and Pt. The fluid slip around the Janus particle enhanced local redox reactions and protected the particle surface from passivation.
Electrocatalytic oxidation of a luminophore at single Au, Pt, and Au‐Pt Janus nanoparticles was studied using electrogenerated chemiluminescence (ECL) microscopy. Compared to the monometal nanoparticles, the Janus particle structure exhibited enhanced ECL intensity and stability, indicating better catalytic efficiency.
China's Chang’e‐5 (CE‐5) has returned 1.731 kg lunar samples from a young mare unit on December 2020. Here, the authors used a spatially resolved numerical model, which considers both impact mixing ...and volcanic effusion, to estimate the evolving distribution of components over the landing region. Using this model, the age composition of surface scooped and sub‐surface drilled CE‐5 samples and their sources were traced back. The proposed model predicts that local mare material predominates in both surface and sub‐surface samples and the nonlocal mare component is ∼1%. There is ∼40% of nonmare component. The composition of both nonmare components in the surface and sub‐surface samples are similar: Abundant components are basin‐sourced melts, where the Imbrium melt are ∼ 25% among all the melt. The ejecta of Sharp B, Harding, Copernicus, and Aristarchus crater that possess different compositions of basin‐sourced melt may have significantly altered the material composition of the landing surface.
Plain Language Summary
Lunar samples provide the ground‐truth reference to reveal the Moon's evolutional history. China's Chang’e‐5 mission is the first lunar exploration program that returned samples since the Luna 24 mission in 1976. Although the sampling site is a young mare basalt, the long‐term impact gardening and multiple volcanic episodes make the composition of the surface material complicated, impeding the interpretation of samples. Here, the authors conduct a numerical simulation that can trace the evolving distribution of different components on the Moon to predict the material composition on the CE‐5 landing region. We found that the local mare material should predominate in both the surface and sub‐surface samples (accounting for 60%). We expect ∼40% nonmare component. The nonmare component should contain abundant impact‐produced melt from the South Pole‐Aitken, Serenitatis, and Imbrium basin. Besides, at the CE‐5 sampling site, the mixture of ejecta from Sharp B, Harding, Copernicus, and Aristarchus crater that have different compositions of basin‐sourced melt cannot be neglected. These predictions can provide useful information for analyzing the provenance of the CE‐5 samples.
Key Points
A numerical model is applied to trace the evolving distribution of components over the Chang’e‐5 landing region
The local mare component should account for ∼60% in the samples
The samples could contain abundant Imbrium melt
• Brassinosteroids have been implicated in the differentiation of vascular cell types in herbaceous plants, but their roles during secondary growth and wood formation are not well defined.
• Here we ...pharmacologically and genetically manipulated brassinosteroid levels in poplar trees and assayed the effects on secondary growth and wood formation, and on gene expression within stems.
• Elevated brassinosteroid levels resulted in increases in secondary growth and tension wood formation, while inhibition of brassinosteroid synthesis resulted in decreased growth and secondary vascular differentiation. Analysis of gene expression showed that brassinosteroid action is positively associated with genes involved in cell differentiation and cell-wall biosynthesis.
• The results presented here show that brassinosteroids play a foundational role in the regulation of secondary growth and wood formation, in part through the regulation of cell differentiation and secondary cell wall biosynthesis.
PDF
