ACS Earth and Space Chemistry最新文献

The catalytic activities displayed by single-atom catalysts (SACs) depend on the coordination structure. SACs supported on carbon materials often adopt saturated coordination structures with uneven distributions because they require high-temperature conditions during synthesis. Herein, bisnitrogen-chelated Co SACs that are coordinatively unsaturated are prepared by integrating a Co complex into a conjugated microporous polymer (CMP-CoN₂). Compared with saturated analogues, i.e., tetranitrogen-chelated Co SACs (denoted as CMP-CoN₄), CMP-CoN₂ exhibits higher electrocatalytic activity in polysulfide conversions due to an enhanced hybridization between the 3d orbitals of the Co atoms and the 3p orbitals of the S atoms in the polysulfide. As a result, sulfur cathodes prepared with CoN₂ deliver outstanding performance metrics, including a high specific capacity (1393 mA h g^–1 at 0.1 C), a superior rate capacity (673.2 mA h g^–1 at 6 C), and a low capacity decay rate (of only 0.045% per cycle at 2 C over 1000 cycles). They also outperform sulfur cathodes that contain CMP-CoN₄ or CMPs that are devoid of Co SACs. This work reveals how the catalytic activity displayed by SACs is affected by their coordination structures, and the rules that underpin the structure–activity relationship may be extended to designing electrocatalysts for use in other applications.

Heterostructures, composed of semiconducting transition-metal dichalcogenides (TMDC) and magnetic van-der-Waals materials, offer exciting prospects for the manipulation of the TMDC valley properties via proximity interaction with the magnetic material. We show that the atomic proximity of monolayer MoSe₂ and the antiferromagnetic van-der-Waals crystal CrSBr leads to an unexpected breaking of time-reversal symmetry, with originally perpendicular spin directions in both materials. The observed effect can be traced back to a proximity-induced exchange interaction via first-principles calculations. The resulting spin splitting in MoSe₂ is determined experimentally and theoretically to be on the order of a few meV. Moreover, we find a more than 2 orders of magnitude longer valley lifetime of spin-polarized charge carriers in the heterostructure, as compared to monolayer MoSe₂/SiO₂, driven by a Mott transition in the type-III band-aligned heterostructure.

High-dielectric-constant (high-k) insulators are indispensable components to integrate semiconductors into metal-oxide-semiconductor field-effect transistors with sub-10 nm channel length, where the equivalent oxide thickness (EOT) of high-k insulator needs to be decreased to subnanometer scale. The traditional insulators, including Al₂O₃, SiO₂, and HfO₂, fit well with the existing silicon industry but suffer from serious degeneration of insulating properties, such as large leakage currents caused by high-density borders and interface traps, when their thicknesses are reduced to a few nanometers. Here, we synthesize a high-quality nonlayered ultrathin α-CaCr₂O₄ crystal down to unit-cell thickness (∼1.2 nm) by an elements slow-supply chemical vapor deposition (CVD) method. The unit-cell-thick α-CaCr₂O₄ crystals show a super high dielectric constant of 87.34, which is over 20 times higher than that of well-known layered insulator h-BN and corresponds to an EOT below 1 nm. Furthermore, it has a high breaking strength (39 GPa) and excellent stability. This strategy can also be used to fabricate other ultrathin ternary oxides, such as high-k ultrathin FeNb₂O₆ crystals, demonstrating the universality of the CVD method.

Thromboembolic stroke constitutes the majority of brain strokes, resulting in elevated mortality and morbidity rates, as well as significant societal and economic burdens. Although intravenous thrombolysis serves as the standard clinical treatment, its narrow therapeutic window and the inflammatory response induced by tissue plasminogen activator (tPA) administration limit its efficacy. In the initial stages of stroke, the abrupt cessation of blood flow leads to an energy metabolism disorder, marked by a substantial decrease in adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH) levels, causing irreversible damage to neural cells. In this study, we introduce a neutrophil-mimetic, microalgae-derived upconversion photosynthetic nanosystem designed for targeted treatment of thromboembolic stroke. This system features upconversion nanoparticles coated with a thylakoid membrane and wrapped in an activated neutrophil membrane, further decorated with ROS-responsive thrombolytic tPA on its surface. The neutrophil-mimetic design facilitates high targeting specificity and accumulation at the thrombus site after intravenous administration. Upon exposure to elevated levels of reactive oxygen species (ROS) at the thrombus location, the nanosystem promptly demonstrated potent thrombolytic efficacy through the surface-modified tPA. Furthermore, near-infrared II (NIR-II) laser irradiation activated the generation of ATP and NADPH, which inhibited inflammatory cell infiltration, platelet activation, oxidative stress, and neuronal injury. This constructed nanoplatform not only showcases exceptional targeting efficiency at the stroke site and controllable release of the thrombolytic agent but also facilitates ATP/NADPH-mediated thrombolytic, anti-inflammatory, antioxidative stress, and neuroprotective effects. Additionally, it offers valuable insights into the potential therapeutic applications of microalgae-based derivatives in managing thromboembolic stroke.

Moiré superstructures arising at twisted 2D interfaces have recently attracted the attention of the scientific community due to exotic quantum states and unique mechanical and tribological behaviors that they exhibit. Here, we predict the emergence of chiral distortions in twisted layered interfaces of finite dimensions. This phenomenon originates in intricate interplay between interfacial interactions and contact boundary constraints. A metric termed the fractional chiral area is introduced to quantify the overall chirality of the moiré superstructure and to characterize its spatial distribution. Despite the equilibrium nature of the discovered energetic and structural chirality effects, they are shown to be manifested in the twisting dynamics of layered interfaces, which demonstrates a continuous transition from stick–slip to smooth rotation with no external trigger.

Nasopharyngeal carcinoma (NPC) is a common malignant tumor of the head and neck, prevalent in regions such as Southern China and Southeast Asia. Radiotherapy serves as the primary clinical treatment for this carcinoma. However, resistance to radiotherapy is a fundamental cause of treatment failure and patient mortality, with the underlying mechanisms yet to be fully elucidated. We identified a recently characterized circular RNA, circADARB1, which is markedly upregulated in NPC tissues and closely associated with poor prognosis and radiotherapy resistance. Both in vitro and in vivo experiments demonstrated that circADARB1 inhibited ferroptosis, thereby inducing radiotherapy resistance in NPC cells. Building on these findings, we synthesized a biomimetic nanomaterial consisting of semiconducting polymer nanoparticles wrapped in cell membranes, designed to deliver both siRNA targeting circADARB1 and iron ions. The application of this nanomaterial not only efficiently suppressed the expression of circADARB1 and boosted intracellular iron concentrations, but also enhanced ferroptosis induced by radiotherapy, improving the radiosensitivity of NPC cells. Furthermore, our study revealed that circADARB1 upregulated the expression of heat shock protein HSP90B1, which repaired misfolded SLC7A11 and GPX4 proteins triggered by radiotherapy, thereby preserving their stability and biological functions. Mechanistically, SLC7A11 facilitated cysteine transportation into cells and glutathione synthesis, while GPX4 employed glutathione to mitigate intracellular lipid peroxidation induced by radiotherapy, shielding cells from oxidative damage and inhibiting ferroptosis, and ultimately leading to radiotherapy resistance in NPC cells. Our investigation elucidates molecular mechanisms with substantial clinical relevance, highlights the promising application prospects of nanotechnology in precision cancer therapy.

Multimodal cancer therapies are often required for progressive cancers due to the high persistence and mortality of the disease and the negative systemic side effects of traditional therapeutic methods. Thus, the development of less invasive modalities for recurring treatment cycles is of clinical significance. Herein, a light-activatable microparticle system was developed for localized, pulsatile delivery of anticancer drugs with simultaneous thermal ablation by applying controlled ON–OFF thermal cycles using near-infrared laser irradiation. The system is composed of poly(caprolactone) microparticles of 200 μm size containing molybdenum disulfide (MoS₂) nanosheets as the photothermal agent and hydrophilic doxorubicin or hydrophobic violacein, as model drugs. Upon irradiation, the nanosheets heat up to ≥50 °C leading to polymer softening and release of the drug. MoS₂ nanosheets exhibit high photothermal conversion efficiency and require low-power laser irradiation. A machine learning algorithm was applied to acquire the optimal laser operation conditions. In a mouse subcutaneous model of 4T1 triple-negative breast cancer, 25 microparticles were intratumorally administered, and after 3-cycle laser treatment, the system conferred synergistic phototherapeutic and chemotherapeutic effects. Our on-demand, pulsatile synergistic treatment resulted in increased median survival up to 39 days post start of treatment compared to untreated mice, with complete eradication of the tumors at the primary site. Such a system is therapeutically relevant for patients in need of recurring cycles of treatment on small tumors, since it provides precise localization and low invasiveness and is not cross-resistant with other treatments.

Nociceptors, crucial sensory receptors within biological systems, are essential for survival in diverse and potentially hazardous environments. Efforts to replicate nociceptors through advanced electronic devices, such as memristors and neuromorphic transistors, have achieved limited success, capturing basic nociceptive functions while more advanced characteristics like various forms of central sensitization and analgesic effect remain out of reach. Here, we introduce a vertical multigate, multichannel electrolyte-gated transistor (Vm-EGT), designed to mimic nociceptors. Utilizing the hybrid mechanism combining electric-double-layer (EDL) with ion intercalation/deintercalation in EGTs, our approach successfully replicates peripheral sensitization and desensitization characteristics of nociceptors. The intricate multigate and multichannel design of the Vm-EGT enables the emulation of more advanced nociceptive functionalities, including central sensitization and analgesic effect. Furthermore, we demonstrate that by exploiting the inherent current–voltage relationship, the Vm-EGT can simulate these advanced nociceptive features and seamlessly transition between them. Integrating a Vm-EGT with a thermistor and a heating plate, we have developed an artificial thermal nociceptor that closely mirrors the sensory attributes of its biological counterpart. Our approach significantly advances the emulation of nociceptors, providing a basis for the development of sophisticated artificial sensory systems and intelligent robotics.

The practical application of Na-ion cathode materials is currently restricted by their low energy density and sluggish dynamics, while the cation-disordered rocksalt (DRX) structures offer a possible solution to the challenge. In this study, among the 24 candidates containing d⁰ elements, we use mixing temperature as a descriptor to screen the synthesizable Na-excess DRX, and we have identified Na_1.2Mn_0.4Mo_0.4O₂ as the most promising candidate that exhibits a Na percolating fraction of 53%, which is higher than that of Li_1.2Mn_0.4Ti_0.4O₂ (35%) proposed in the previous study due to the larger lattice constant in Na-excess DRX cathodes. More importantly, Na_1.2Mn_0.4Mo_0.4O₂ is predicted to have a capacity of 228 mAh/g with an energy density of 552 Wh/kg derived from percolation theory and cluster-expansion Monte Carlo simulations, which is higher than that of Na_1.3Nb_0.3Mn_0.4O₂ and Na_1.14Mn_0.57Ti_0.29O₂ synthesized recently. For a better understanding, the redox mechanism is explored, which involves Mo⁴⁺/Mo⁶⁺, Mn³⁺/Mn⁴⁺, and O^2–/O^n– (0 < n < 2), indicating the participation of anionic redox. Meanwhile, the Na⁺ diffusion prefers a divacancy mechanism via an o-t-o diffusion channel with a low diffusion barrier of 0.29 eV. This study expands the family of DRX for the cathode of Na-ion batteries with enhanced performance.

Quantum information processing demands efficient quantum light sources (QLS) capable of producing high-fidelity single photons or entangled photon pairs. Single epitaxial quantum dots (QDs) have long been proven to be efficient sources of deterministic single photons; however, their production via molecular-beam epitaxy presents scalability challenges. Conversely, colloidal semiconductor QDs offer scalable solution processing and tunable photoluminescence, but suffer from broader linewidths and unstable emissions. This leads to spectrally inseparable emission from exciton (X) and biexciton (XX) states, complicating the production of single photons and triggered photon pairs. Here, we demonstrate that colloidal semiconductor quantum shells (QSs) achieve significant spectral separation (∼75–80 meV) and long temporal stability of X and XX emissive states, enabling the observation of exciton-biexciton bunching in colloidal QDs. Our low-temperature single-particle measurements show cascaded XX-X emission of single photon pairs for over 200 s, with minimal overlap between X and XX features. The X-XX distinguishability allows for an in-depth theoretical characterization of cross-correlation strength, placing it in perspective with photon pairs of epitaxial counterparts. These findings highlight a strong potential of semiconductor quantum shells for applications in quantum information processing.