Search

Bacteria‐mediated tumor therapy (BMTT) has been known for decades; however, its clinical use is inhibited by its association with infections. To address this issue, a spiky, bacterium‐like metal–organic framework (MOF), which can replicate the functional responses of BMTT without its adverse side‐effects, is proposed. MOFs are synthesized in a solvothermal reaction of aluminum sulfate, ruthenium chloride hydrate, and 2‐aminoterephthalic acid; they have a spherical morphology or many nanospikes on their surfaces, depending on the reaction temperature. Both spherical and spiky MOFs can function as photothermal agents, converting absorbed optical energy into local heat. Owing to their higher surface area of interaction, spiky MOFs are more easily phagocytosed by macrophages than are spherical MOFs, strengthening their immune responses. Moreover, when injected intratumorally, spiky MOFs reside significantly longer than spherical ones, enabling their use in repeated photothermal treatments. The combination of in situ vaccination with intratumorally injected bacterium‐like MOFs under exposure to an near‐infrared laser and the immune checkpoint blockade of systemically administered αPD‐1 is evaluated in tumor‐bearing mice. The results indicate that the checkpoint blockade acts synergistically with in situ vaccination to provide diverse antitumor functions of BMTT, destroying a primary tumor and suppressing tumor recurrence and metastasis. [ABSTRACT FROM AUTHOR]

Manipulation of electron beam irradiation using TEM determines the selective region with a particular size and depth to conduct the subsequent process for nanopore formation. • Recording the effect of e-beam irradiation on Mo 5 O 14 nanowires by in situ TEM. • Manipulating e-beam to define the anticipated region and the size of nanoporosity. • Atom removal and crystallinity degradation resulting in structural transformation. • The formation of nanopores due to the numerous broken bonds in crystalline Mo 5 O 14. • Revealing the mechanism of selective nanopore formation in nanoscale modification. The Mo 5 O 14 -type structure is representative of the MoO-based catalyst in the selective oxidation process. Single-crystalline Mo 5 O 14 nanowires can be synthesized in a controlled manner by chemical vapor deposition (CVD). A nanowire catalyst with a porous structure combines the advantages of both nanoparticles and nanowires, leading to a substantial increase in the specific surface area. Therefore, we aim to manipulate the e-beam irradiation process on Mo 5 O 14 nanowires to induce the nanoporous structures in selected regions. In situ transmission electron microscopy (TEM) enabled us to visualize the structural transformation through gradual e-beam irradiation. The e-beam irradiation process removes oxygen atoms and renders the internal structure unstable. After the irradiated region is exposed to air, atoms tend to escape to decrease the internal energy. This results in the formation of nanopores because of the irradiation effect. By nanoscale modification method, the irradiated region is controlled by the electron beam size, which determines the nanopore distribution in the selected region. The study is beneficial for increasing the surface area of Mo 5 O 14 -type catalysts with variable nanopore densities and for modifying nanomaterials using a convenient method. [ABSTRACT FROM AUTHOR]

The atomic scale Silicidation of Ni-Si System by In-situ TEM Investigation could be divide into three steps. At the first step (250 °C), Ni would diffuse into Si substrate to synthesize triangular Ni 2 Si. Afterwards, continuous NiSi thin films would be synthesized at 400 °C. At last, trapezoid NiSi would react with Si to form NiSi 2 at third step (600 °C). Furthermore, the electric electrical properties of Ni-Si system were identified by four-point probe measurements; the resistivities of NiSi, Ni 2 Si and NiSi 2 were 14.13 µΩ∙cm, 22.80 µΩ∙cm and 37.77 µΩ∙cm, respectively. • The diffusion behaviour of Ni-Si system was investigated through in situ HRTEM. • Ni 2 Si and NiSi were diffusion controlled and NiSi 2 was nucleation controlled. • The resistivities of NiSi, Ni 2 Si and NiSi 2 were 14.1, 22.8, and 37.7 µΩ∙cm, respectively. • The diffusion rate could be calculated by in-situ TEM observation. • This work provides a novel method to obtain low resistivity silicide for IC devices. Nickel silicide has many advantages, such as low resistivity and low formation temperature; therefore, it has been widely used in the fields of solar cells, transistors and complementary metal-oxidesemiconductor (CMOS) devices. To obtain high-quality nickel-silicide thin film, solid-state reaction is a convenient and efficient fabrication method. For better understanding of the dynamic formation mechanism, we used in-situ transmission electron microscopy (TEM) to record the diffusion behavior during the heating process. In this work, three-steps annealing process to synthesize different nickel silicides corresponding to the various formation temperatures were investigated systematically. At 250 °C, the product of the first-step annealing was inverted-triangle Ni 2 Si, embedded in the Si substrate. Then, well-distributed NiSi thin film was synthesized, having the lowest resistivity among Ni-Si system at 400 °C. Finally, NiSi 2 , a Si-rich product, would form during the third-step annealing at 600 °C. NiSi 2 product and Si substrate have small lattice mismatch; thus, the epitaxial relationship would be observed. We provide the evidence of diffusion behaviors and structural identification of Ni-Si system. Furthermore, these results are beneficial for the formation of specific nickel silicides, which is expected to optimize the fabrication of microelectronics. [ABSTRACT FROM AUTHOR]

The technologies of 3D vertical architecture have made a major breakthrough in establishing high‐density memory structures. Combined with an array structure, a 3D high‐density vertical resistive random access memory (VRRAM) cross‐point array is demonstrated to efficiently increase the device density. Though electrochemical migration (ECM) resistive random access (RRAM) has the advantage of low power consumption, the stability of the operating voltage requires further improvements due to filament expansions and deterioration. In this work, 3D‐VRRAM arrays are designed. Two‐layered RRAM cells, with one inert and one active sidewall electrode stacked at a cross‐point, are constructed, where the thin film sidewall electrode in the VRRAM structure is beneficial for confining the expansions of the conducting filaments. Thus, the top cell (Pt/ZnO/Pt) and the bottom cell (Ag/ZnO/Pt) in the VRRAM structure, which are switched by different mechanisms, can be analyzed at the same time. The oxygen vacancy filaments in the Pt/ZnO/Pt cell and Ag filaments in the Ag/ZnO/Pt cell are verified. The 40 nm thickness sidewall electrode restricts the filament size to nanoscale, which demonstrates the stability of the operating voltages. Additionally, the 0.3 V operating voltage of Ag/ZnO/Pt ECM VRRAM demonstrates the potential of low power consumption of VRRAM arrays in future applications. [ABSTRACT FROM AUTHOR]

Resistive random‐access memory (ReRAM) is one of the most promising types of nonvolatile memory because it has several important advantages, for example, a simple metal‐insulator‐metal structure, fast operating speed, high endurance, high retention, and low energy consumption. However, the reliability of ReRAM nanodevices is not persistent, and the complete switching mechanism is not fully understood. In this study, a unique 1D Ni/NiO/HfO2 core/multishell ReRAM nanodevice is designed and fabricated. The different properties, including the electrical characteristics, surface morphology, and elemental distribution, are systematically investigated. The Ni/NiO/HfO2 heterostructure nanowire ReRAM device exhibits excellent electrical characteristics and resistive switching properties. It is remarkable that the endurance could be maintained up to 200 cycles, which is extremely good for a 1D ReRAM device. Additionally, a focused‐ion beam technique is used to prepare samples for subsequent transmission electron microscopic (TEM) observation. From the TEM analysis, the position of the conducting filaments is verified and the elemental composition of the conducting filaments is confirmed. The migration of hafnium ions forms the conducting filaments between the HfO2 layer and Ni core, resulting in the switching characteristic. The study enriches the understanding of the mechanism and provides a design to enhance the resistive switching properties of ReRAM nanodevices. A Ni/NiO/HfO2 core/multishell nanowire ReRAM device could improve the endurance and reliability of one‐dimensional nanodevices. Electrical measurements exhibit excellent resistive switching properties, and the endurance is maintained up to 200 cycles. From HRTEM and STEM images, the structure is identified as being composed of conducting filaments, showing that the conducting filaments are composed of crystalline Hf. [ABSTRACT FROM AUTHOR]

A significant grain rotation in < 111 >-oriented nanotwinned Cu film under tensile test at room temperature is reported. After rotation, the dislocation network in low angle tilt-type boundaries increases the strain energy, which provides the driving force for recrystallization in a subsequent annealing, resulting in the formation of millimeter size grains. [ABSTRACT FROM AUTHOR]