Comparison of regional cerebral blood flow in Parkinson's disease with depression and major depression

Diagnosis of depression in Parkinson's disease (PD) patients is complicated due to the overlapping symptoms of the two disorders. We investigated regional cerebral blood flow (rCBF) in patients with only major depression (MD) and PD patients with (PDMD) and without MD (PDNMD) using ^99mTc hexamethylpropyleneamine oxime single photon emission computed tomography (HMPAO‐SPECT). A total of 103 patients (38 PDMD, 46 PDNMD, and 19 MD patients) underwent brain HMPAO‐SPECT scans. Voxel‐wise whole‐brain analysis was conducted to compare rCBF of the PDMD group with that of the PDNMD and MD groups. The scores of the Geriatric Depression Scale (GDS) and Neuropsychiatric Inventory (NPI) were significantly higher in the PDMD group than in the PDNMD group. The PDMD group showed significant hypoperfusion in the subcallosal cortex than the PDNMD group. The MD group showed significant hypoperfusion in the brainstem and inferomedial frontal region compared with the PDMD group. Our findings suggest that dysfunction of the inferomedial frontal cortex may be involved in the pathogenesis of depression in PD patients.     

Interface Control of Ferroelectricity in an SrRuO3/BaTiO3/SrRuO3 Capacitor and its Critical Thickness

The atomic‐scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure during growth plays an important role in controlling the interfacial terminations of SrRuO₃/BaTiO₃/SrRuO₃ (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high (around 150 mTorr), usually exhibits a mixture of RuO₂–BaO and SrO–TiO₂ terminations. By reducing , the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO–TiO₂ termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells.     

Exceptional High‐Performance of Pt‐Based Bimetallic Catalysts for Exclusive Detection of Exhaled Biomarkers

Achieving an improved understanding of catalyst properties, with ability to predict new catalytic materials, is key to overcoming the inherent limitations of metal oxide based gas sensors associated with rather low sensitivity and selectivity, particularly under highly humid conditions. This study introduces newly designed bimetallic nanoparticles (NPs) employing bimetallic Pt‐based NPs (PtM, where M = Pd, Rh, and Ni) via a protein encapsulating route supported on mesoporous WO₃ nanofibers. These structures demonstrate unprecedented sensing performance for detecting target biomarkers (even at p.p.b. levels) in highly humid exhaled breath. Sensor arrays are further employed to enable pattern recognition capable of discriminating between simulated biomarkers and controlled breath. The results provide a new class of multicomponent catalytic materials, demonstrating potential for achieving reliable breath analysis sensing.     

Brain‐Inspired Photonic Neuromorphic Devices using Photodynamic Amorphous Oxide Semiconductors and their Persistent Photoconductivity

The combination of a neuromorphic architecture and photonic computing may open up a new era for computational systems owing to the possibility of attaining high bandwidths and the low‐computation‐power requirements. Here, the demonstration of photonic neuromorphic devices based on amorphous oxide semiconductors (AOSs) that mimic major synaptic functions, such as short‐term memory/long‐term memory, spike‐timing‐dependent plasticity, and neural facilitation, is reported. The synaptic functions are successfully emulated using the inherent persistent photoconductivity (PPC) characteristic of AOSs. Systematic analysis of the dynamics of photogenerated carriers for various AOSs is carried out to understand the fundamental mechanisms underlying the photoinduced carrier‐generation and relaxation behaviors, and to search for a proper channel material for photonic neuromorphic devices. It is found that the activation energy for the neutralization of ionized oxygen vacancies has a significant influence on the photocarrier‐generation and time‐variant recovery behaviors of AOSs, affecting the PPC behavior.     

Atomic-Scale Metal–Insulator Transition in SrRuO3 Ultrathin Films Triggered by Surface Termination Conversion

The metal–insulator transition (MIT) in transition-metal-oxide is fertile ground for exploring intriguing physics and potential device applications. Here, an atomic-scale MIT triggered by surface termination conversion in SrRuO₃ ultrathin films is reported. Uniform and effective termination engineering at the SrRuO₃(001) surface can be realized via a self-limiting water-leaching process. As the surface termination converts from SrO to RuO₂, a highly insulating and nonferromagnetic phase emerges within the topmost SrRuO₃ monolayer. Such a spatially confined MIT is corroborated by systematic characterizations on electrical transport, magnetism, and scanning tunneling spectroscopy. Density functional theory calculations and X-ray linear dichroism further suggest that the surface termination conversion breaks the local octahedral symmetry of the crystal field. The resultant modulation in 4d orbital occupancy stabilizes a nonferromagnetic insulating surface state. This work introduces a new paradigm to stimulate and tune exotic functionalities of oxide heterostructures with atomic precision.     

Sensitive Wearable Temperature Sensor with Seamless Monolithic Integration

Accurate temperature field measurement provides critical information in many scientific problems. Herein, a new paradigm for highly sensitive, flexible, negative temperature coefficient (NTC) thermistor-based artificial skin is reported, with the highest temperature sensing ability reported to date among previously reported NTC thermistors. This artificial skin is achieved through the development of a novel monolithic laser-induced reductive sintering scheme and unique monolithic structures. The unique seamless monolithic structure simultaneously integrates two different components (a metal electrode and metal oxide sensing channel) from the same material at ambient pressure, which cannot be achieved by conventional heterogeneous integration through multiple, complex steps of photolithography or vacuum deposition. In addition to superior performance, electronic skin with high temperature sensitivity can be fabricated on heat-sensitive polymer substrates due to the low-temperature requirements of the process. As a proof of concept, temperature-sensitive artificial skin is tested with conformally attachable physiological temperature sensor arrays in the measurement of the temperatures of exhaled breath for the early detection of pathogenic progression in the respiratory system. The proposed highly sensitive flexible temperature sensor and monolithic selective laser reductive sintering are expected to greatly contribute to the development of essential components in various emerging research fields, including soft robotics and healthcare systems.     

2D MXene–TiO2 Core–Shell Nanosheets as a Data-Storage Medium in Memory Devices

MXenes, an emerging class of 2D transition metal carbides and nitrides with the general formula M_n+1X_nT_x (n = 1–4), have potential for application as floating gates in memory devices because of their intrinsic properties of a 2D structure, high density-of-states, and high work function. In this study, a series of MXene–TiO₂ core–shell nanosheets are synthesized by deterministic control of the surface oxidation of MXene. The floating gate (multilayer MXene) and tunneling layer (TiO₂) in a nano-floating-gate transistor memory (NFGTM) device are prepared simultaneously by a facile, low-cost, and water-based process. The memory performance is optimized via adjustment of the thickness of the oxidation layer formed on the MXene surface. The fabricated MXene NFGTMs exhibit excellent nonvolatile memory characteristics, including a large memory window (>35.2 V), high programming/erasing current ratio (≈10⁶), low off-current (<1 pA), long retention (>10⁴ s), and cyclic endurance (300 cycles). Furthermore, synaptic functions, including the excitatory postsynaptic current/inhibitory postsynaptic current, paired-pulse facilitation, and synaptic plasticity (long-term potentiation/depression), are successfully emulated using the MXene NFGTMs. The successful control of MXene oxidation and its application to NFGTMs are expected to inspire the application of MXene as a data-storage medium in future memory devices.     

Epitaxially Strained CeO2/Mn3O4 Nanocrystals as an Enhanced Antioxidant for Radioprotection

Nanomaterials with antioxidant properties are promising for treating reactive oxygen species (ROS)-related diseases. However, maintaining efficacy at low doses to minimize toxicity is a critical for clinical applications. Tuning the surface strain of metallic nanoparticles can enhance catalytic reactivity, which has rarely been demonstrated in metal oxide nanomaterials. Here, it is shown that inducing surface strains of CeO₂/Mn₃O₄ nanocrystals produces highly catalytic antioxidants that can protect tissue-resident stem cells from irradiation-induced ROS damage. Manganese ions deposited on the surface of cerium oxide (CeO₂) nanocrystals form strained layers of manganese oxide (Mn₃O₄) islands, increasing the number of oxygen vacancies. CeO₂/Mn₃O₄ nanocrystals show better catalytic activity than CeO₂ or Mn₃O₄ alone and can protect the regenerative capabilities of intestinal stem cells in an organoid model after a lethal dose of irradiation. A small amount of the nanocrystals prevents acute radiation syndrome and increases the survival rate of mice treated with a lethal dose of total body irradiation.     

Flexible/Stretchable Supercapacitors with Novel Functionality for Wearable Electronics

With the miniaturization of personal wearable electronics, considerable effort has been expended to develop high-performance flexible/stretchable energy storage devices for powering integrated active devices. Supercapacitors can fulfill this role owing to their simple structures, high power density, and cyclic stability. Moreover, a high electrochemical performance can be achieved with flexible/stretchable supercapacitors, whose applications can be expanded through the introduction of additional novel functionalities. Here, recent advances in and future prospects for flexible/stretchable supercapacitors with innate functionalities are covered, including biodegradability, self-healing, shape memory, energy harvesting, and electrochromic and temperature tolerance, which can contribute to reducing e-waste, ensuring device integrity and performance, enabling device self-charging following exposure to surrounding stimuli, displaying the charge status, and maintaining the performance under a wide range of temperatures. Finally, the challenges and perspectives of high-performance all-in-one wearable systems with integrated functional supercapacitors for future practical application are discussed.