Coherent phonon generation and detection in ultrathin SrTiO3 grown directly on silicon

Time‐resolved two color pump‐probe polarization spectroscopy was performed at room temperature on SrTiO₃ films grown directly on Si with film thickness varying from 2 nm to 7.8 nm. An E‐symmetry mode with a characteristic frequency of 0.2 THz is impulsively generated and measured in these coherently strained tetragonal phase SrTiO₃ thin films. A superimposed exponentially decaying signal observed indicates the possible relaxational hopping of Ti ion between double potential wells. The dependence of the coherent phonon signal on pump and probe laser polarization helps to identify the symmetry of the phonon modes.     

多孔材料塑性极限载荷及其破坏模式分析

运用塑性力学中的机动极限分析理论，研究韧性基体多孔材料的塑性极限承载能力和破坏模式。以多孔材料的细观结构为研究对象，将细观力学中的均匀化理论引入到塑性极限分析中，并结合有限元技术，建立细观结构极限载荷的一般计算格式，并提出相应的求解算法。数值算例表明：细观孔洞对材料的宏观强度影响明显；在单向拉伸作用下，孔洞呈现膨胀扩大规律；多孔材料破坏源于基体塑性区的贯通。     

极限下限分析的正交基无单元Galerkin法

基于极限分析的下限定理,建立了用正交基无单元Galerkin法进行理想弹塑性结构极 限分析的整套求解算法．下限分析所需的虚拟弹性应力场可由正交基无单元Galerkin法直接 得到,所需的自平衡应力场由一组带有待定系数的自平衡应力场基矢量的线性组合进行模 拟．这些自平衡应力场基矢量可由弹塑性增量分析中的平衡迭代得到．通过对自平衡应力场 子空间的不断修正,整个问题的求解将化为一系列非线性数学规划子问题,并通过复合形法 进行求解．算例表明该方法有效地克服了维数障碍问题,使计算效率得到了充分的提高,是 切实可行的．     

A Near-Infrared Light-Responsive ROS Cascade Nanoplatform for Synergistic Therapy Potentiating Antitumor Immune Responses

Tumor occurrence is closely related to the unlimited proliferation and the evasion of the immune surveillance. However, it remains a challenge to kill tumor cells and simultaneously activate antitumor immunity upon spatially localized external stimuli. Herein, a robust tumor synergistic therapeutic nanoplatform is designed in combination with dual photosensitizers-loaded upconversion nanoparticles (UCNPs) and ferric-tannic acid (FeTA) nanocomplex. Dual photosensitizers-loaded UCNPs can induce photodynamic therapy (PDT) effect by generation of cytotoxic reactive oxygen species (ROS) on demand under near-infrared (NIR) light irradiation. FeTA can robustly respond to acidic tumor microenvironment to produce Fe²⁺ and subsequently induce chemodynamic therapy (CDT) by reacting with H₂O₂ in the tumor microenvironment. More importantly, the CDT/PDT synergy can not only exhibit significant antitumor ability but also induce ROS cascade to evoke immunogenic cell death. It increases tumor immunogenicity and promotes immune cell infiltration at tumor sites allowing further introduction of systemic immunotherapy responsiveness to inhibit the primary and distant tumor growth. This study provides a potential tumor microenvironment-responsive nanoplatform for imaging-guided diagnosis and combined CDT/PDT with improved immunotherapy responses and an external NIR-light control of photoactivation.     

The Self-Adaptive Nanosystem for Implant-Related Infections Theranostics via Phase-Change Driven Anti-Biofilm and the Enhancement of Immune Memory

Implant-related infections (IRIs), characterized by the formation of bacterial biofilms and immunosuppressive microenvironment, are a common but tricky clinical issue. In this study, a self-adaptive theranostics nanosystem is designed based on phase change material (PCM) for IRIs therapy, which can monitor the severity of infection in real time and automatically provide the most appropriate treatment on demand. The nanosystem called CaAlg/LOD/POD@MNO/FAs (CLPM) is made of the fatty acids (FAs) core with dissolved minocycline (MNO) and the calcium alginate (CaAlg) shell with an immobilized lactate oxidase/pyruvate oxidase (LOD/POD) enzyme-linked system. When the level of infection is mild (wound temperature < 39 °C), the CLPMs perform a bacteriostatic function by slowly releasing MNO from the solid-phase FAs core. When the infection deteriorates (wound temperature > 39 °C), the solid-to-liquid phase change of FAs not only enables a rapid release of MNO but also disrupts the mechanical strength of the biofilm skeleton doped with CLPM, performing a bactericidal function. In addition, CLPM can reduce the accumulation of bacteria-derived lactate to address lactate-induced immunosuppression and enhance immune memory response, thereby inhibiting infection recurrence.     

Photoinduced Contact Evolution and Junction Rearrangement in Two-Dimensional van der Waals Heterostructure

Devices based on 2DMs van der Waals (vdW) heterostructures always compose of multiple contacts. Due to the instability of nanoscale 2DMs and interfaces, these contacts can be affected by the operation-induced photo or thermal effect. They can trigger the evolution of junctions and rearrange the junctions across a device, which are detrimental for applications. Herein, vdW heterostructure of indium selenide (InSe) and black phosphorus (BP) on Au electrodes are investigated to reveal the contact evolution and its relation to device performance. During operation, light irradiation changes the I–V characteristics from symmetry to strong rectification. Photocurrent mapping and Kelvin-probe force microscopy (KPFM) reveal triple junctions in this heterostructure, i.e., Au-InSe junction, InSe homojunction, and InSe-BP heterojunction. The variation of I–V characteristics of vdW heterostructure is ascribed to the evolution of Au-InSe junction from quasi-ohmic junction with a near-zero work function difference (Δφ) to a strong Schottky junction (Δφ = ≈0.27 eV). The stabilized device demonstrates distinguished time-domain response at individual junctions and overall device, indicating the evolution of contacts and the consequent opposite junction directions degrade the overall device performance. This research emphasizes the importance of dealing with heterogeneous contacts and junction directions in designing vdW heterostructure photodetectors.     

Reply to Correspondence on “Structural Insight into the Catalytic Mechanism of the Endoperoxide Synthase FtmOx1′′

The high-resolution X-ray crystal structure of the ternary complex FtmOx1 ⋅ 2OG ⋅ fumitremorgin B and the catalytic mechanism were recently reported by us (DOI 10.1002/anie.202112063 ). In their Correspondence, Zhang, Costello, Liu et al. criticize our work in several aspects. Herein, we address these questions one by one. These structural clarifications and new computational results further support the CarC-like mechanistic model.