Tailored synthesis of circular polyolefins
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Colloidal clusters as models for circular microswimmers
Circular swimmers, particles that propel in circular trajectories, are gaining traction due to their potential for novel collective behaviors. However, synthetic active particles capable of controlled circular propulsion remain scarce. We present a facile experimental strategy to fabricate synthetic swimmers using chemically cross-linked Janus colloid clusters, driven by induced charge electrophoresis. By quantifying the propulsion dynamics of active clusters, we demonstrate that cluster geometry dictates orbit diameter, angular velocity, and chirality. Through statistical analysis of clusters, we identify compact clusters as promising candidates for tunable circular propulsion. To scale up fabrication, we employ capillary-assisted assembly for achieving monodisperse clusters. Our validation of the kinetic model for active trimers and tetramers suggests that clustering as a strategy for circular propulsion extends to Janus colloids propelled by different mechanisms. Our findings establish Janus clusters as versatile systems for controlled circular propulsion, enabling new experimental studies on the collective behavior of circular microswimmers.
Flash Joule heating for synthesis, upcycling and remediation
Electric heating methods are being developed and used to electrify industrial applications and lower their carbon emissions. Direct Joule resistive heating is an energy-efficient electric heating technique that has been widely tested at the bench scale and could replace some energy-intensive and carbon-intensive processes. In this Review, we discuss the use of flash Joule heating (FJH) in processes that are traditionally energy-intensive or carbon-intensive. FJH uses pulse current discharge to rapidly heat materials directly to a desired temperature; it has high-temperature capabilities (>3,000 °C), fast heating and cooling rates (>102 °C s−1), short duration (milliseconds to seconds) and high energy efficiency (~100%). Carbon materials and metastable inorganic materials can be synthesized using FJH from virgin materials and waste feedstocks. FJH is also applied in resource recovery (such as from e-waste) and waste upcycling. An emerging application is in environmental remediation, where FJH can be used to rapidly degrade perfluoroalkyl and polyfluoroalkyl substances and to remove or immobilize heavy metals in soil and solid wastes. Life-cycle and technoeconomic analyses suggest that FJH can reduce energy consumption and carbon emissions and be cost-efficient compared with existing methods. Bringing FJH to industrially relevant scales requires further equipment and engineering development.
Anion vacancies activate N2 to ammonia on Ba–Si orthosilicate oxynitride-hydride
Anion vacancies on metal oxide surfaces have been studied as either active sites or promoting sites in various chemical reactions involving oxidation/reduction processes. However, oxide materials rarely work effectively as catalysts in the absence of transition metal sites. Here we report a Ba–Si orthosilicate oxynitride–hydride as a transition-metal-free catalyst for efficient ammonia synthesis via an anion-vacancy–mediated mechanism. The facile desorption of H− and N3− anions plus the flexibility of the crystal structure can accommodate a high density of electrons at vacancy sites, where N2 can be captured and directly activated to ammonia through hydrogenation processes. The ammonia synthesis rates reach 40.1 mmol g−1 h−1 at 300 °C by loading ruthenium nanoparticles. Although not found to dissociate N2, Ru instead facilitates the formation of anion vacancies at the Ru–support interface. This demonstrates a new route for anion-vacancy–mediated heterogeneous catalysis.
Enantioselective synthesis of chiroplasmonic helicoidal nanoparticles by nanoconfinement in chiral dielectric shells
Helicoid metal nanoparticles with intrinsic chirality have unveiled tailorable properties and unlocked many chirality-related applications across various fields. Nevertheless, the existing strategies for enantioselective synthesis of helicoid metal nanoparticles have been predominantly limited to gold. Here, we demonstrate a robust and versatile strategy for the enantioselective synthesis of helicoid nanoparticles beyond gold, leveraging chiral nanoconfinement provided by chiral SiO2 or nanoshells. The chiral nanoconfinement strategy enables the decoupling of ligand-directed crystal growth from chiral induction, allowing for the independent tuning of these two critical aspects. As a result, this approach can not only facilitate the replication of chiral shapes from the chiral nanoshells but also allow the generation of alternative chiral shapes. By employing this approach, we demonstrate the enantioselective synthesis of helicoid Pt, Au@Pt, Au@Pd, Au@Ag, and Au@Cu nanoparticles. The chiroplasmonic properties of Pt- and Pd-based chiral nanoparticles have been discovered, and the inversion of chiroplasmonic properties of Ag-based chiral nanoparticles via facet control has been documented and theoretically explained. The chiral nanoconfinement strategy enriches the toolbox for creating chiral nanoparticles and supports their exploration in diverse applications.
Reprogramming of fatty acid metabolism: a hidden force regulating the occurrence and progression of cholangiocarcinoma
Cholangiocarcinoma (CCA) is a malignant tumor that originates from the bile duct epithelium and with a poor outcome due to lack of effective early diagnostic methods. Surgical resection is the preferred method for cure, but treatment options are limited for advanced diseases, such as distant metastatic or locally progressive tumors. Therefore, it is urgent to explore other new treatment methods. As modern living standards rise, the acceptance of high-fat, high-protein, and high-carbohydrate diets is growing among the public, and the resulting metabolic abnormalities are intimately linked to the initiation and spread of tumors. Metabolic reprogramming is a key mechanism in the process of tumor development and progression and is closely related to cancer cell proliferation, metastasis and drug resistance. Fatty acid (FA) metabolism, an integral component of cancer cell metabolism, can provide an energy source for cancer cells and participate in cell signaling, the regulation of the immune response and the maintenance of homeostasis of the internal environment, which are closely linked to the development and progression of CCA. Therefore, a better understanding of FA metabolism may provide promising strategies for early diagnosis, prognostic assessment and targeted therapy for CCA patients. In this paper, we review the effects of FA metabolism on CCA development and progression, summarize related mechanisms and the existing clinical applications of targeted lipid metabolism in CCA, and explore new targets for CCA metabolic therapy.
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