Synergistically Modulating Conductive Filaments in Ion-Based Memristors for Enhanced Analog In-Memory Computing.

Memristors offer a promising solution to address the performance and energy challenges faced by conventional von Neumann computer systems. Yet, stochastic ion migration in conductive filament often leads to an undesired performance tradeoff between memory window, retention, and endurance. Herein, a robust memristor based on oxygen-rich SnO2 nanoflowers switching medium, enabled by seed-mediated wet chemistry, to overcome the ion migration issue for enhanced analog in-memory computing is reported. Notably, the interplay between the oxygen vacancy (Vo) and Ag ions (Ag+ ) in the Ag/SnO2 /p++ -Si memristor can efficiently modulate the formation and abruption of conductive filaments, thereby resulting in a high on/off ratio (>106), long memory retention (10-year extrapolation), and low switching variability (SV = 6.85%). Multiple synaptic functions, such as paired-pulse facilitation, long-term potentiation/depression, and spike-time dependent plasticity, are demonstrated. Finally, facilitated by the symmetric analog weight updating and multiple conductance states, a high image recognition accuracy of ≥ 91.39% is achieved, substantiating its feasibility for analog in-memory computing. This study highlights the significance of synergistically modulating conductive filaments in optimizing performance trade-offs, balancing memory window, retention, and endurance, which demonstrates techniques for regulating ion migration, rendering them a promising approach for enabling cutting-edge neuromorphic applications.

Technology and Integration Roadmap for Optoelectronic Memristor.

Optoelectronic memristors (OMs) have emerged as a promising optoelectronic Neuromorphic computing paradigm, opening up new opportunities for neurosynaptic devices and optoelectronic systems. These OMs possess a range of desirable features including minimal crosstalk, high bandwidth, low power consumption, zero latency, and the ability to replicate crucial neurological functions such as vision and optical memory. By incorporating large-scale parallel synaptic structures, OMs are anticipated to greatly enhance high-performance and low-power in-memory computing, effectively overcoming the limitations of the von Neumann bottleneck. However, progress in this field necessitates a comprehensive understanding of suitable structures and techniques for integrating low-dimensional materials into optoelectronic integrated circuit platforms. This review aims to offer a comprehensive overview of the fundamental performance, mechanisms, design of structures, applications, and integration roadmap of optoelectronic synaptic memristors. By establishing connections between materials, multilayer optoelectronic memristor units, and monolithic optoelectronic integrated circuits, this review seeks to provide insights into emerging technologies and future prospects that are expected to drive innovation and widespread adoption in the near future.

Prepared MW-Immunosensitizers Precisely Release NO to Downregulate HIF-1α Expression and Enhance Immunogenic Cell Death.

Microwave thermotherapy (MWTT) has limited its application in the clinic due to its high rate of metastasis and recurrence after treatment. Nitric oxide (NO) is a gaseous molecule that can address the high metastasis and recurrence rates after MWTT by increasing thermal sensitivity, down-regulating the expression of hypoxia-inducible factor-1 (HIF-1), and inducing the immunogenic cell death (ICD). Therefore, GaMOF-Arg is designed, a gallium-based organic skeleton material derivative loaded with L-arginine (L-Arg), and coupled the mitochondria-targeting drug of triphenylphosphine (TPP) on its surface to obtain GaMOF-Arg-TPP (GAT) MW-immunosensitizers. When GAT MW-immunosensitizers are introduced into mice through the tail vein, reactive oxygen species (ROS) are generated and L-Arg is released under MW action. Then, L-Arg reacts with ROS to generate NO, which not only downregulates HIF-1 expression to improve tumor hypoxia exacerbated by MW, but also enhances immune responses by augment calreticulin (CRT) exposure, high mobility group box 1 (HMGB1) release, and T-cell proliferation to achieve prevention of tumor metastasis and recurrence. In addition, NO can induce mitochondria damage to increase their sensitivity to MWTT. This study provides a unique insight into the use of metal-organic framework MW-immunosensitizers to enhance tumor therapy and offers a new way to treat cancer efficiently.

Organic photodiodes with bias-switchable photomultiplication and photovoltaic modes.

The limited sensitivity of photovoltaic-type photodiodes makes it indispensable to use pre-amplifier circuits for effectively extracting electrical signals, especially when detecting dim light. Additionally, the photomultiplication photodiodes with light amplification function suffer from potential damages caused by high power consumption under strong light. In this work, by adopting the synergy strategy of thermal-induced interfacial structural traps and blocking layers, we develop a dual-mode visible-near infrared organic photodiode with bias-switchable photomultiplication and photovoltaic operating modes, exhibiting high specific detectivity (~1012 Jones) and fast response speed (0.05/3.03 ms for photomultiplication-mode; 8.64/11.14 µs for photovoltaic-mode). The device also delivers disparate external quantum efficiency in two optional operating modes, showing potential in simultaneously detecting dim and strong light ranging from ~10-9 to 10-1 W cm-2. The general strategy and working mechanism are validated in different organic layers. This work offers an attractive option to develop bias-switchable multi-mode organic photodetectors for various application scenarios.

Stabilizing Non-Fullerene Organic Photodiodes through Interface Engineering Enabled by a Tin Ion-Chelated Polymer.

The recent emergence of non-fullerene acceptors (NFAs) has energized the field of organic photodiodes (OPDs) and made major breakthroughs in their critical photoelectric characteristics. Yet, stabilizing inverted NF-OPDs remains challenging because of the intrinsic degradation induced by improper interfaces. Herein, a tin ion-chelated polyethyleneimine ethoxylated (denoted as PEIE-Sn) is proposed as a generic cathode interfacial layer (CIL) of NF-OPDs. The chelation between tin ions and nitrogen/oxygen atoms in PEIE-Sn contributes to the interface compatibility with efficient NFAs. The PEIE-Sn can effectively endow the devices with optimized cascade alignment and reduced interface defects. Consequently, the PEIE-Sn-OPD exhibits properties of anti-environmental interference, suppressed dark current, and accelerated interfacial electron extraction and transmission. As a result, the unencapsulated PEIE-Sn-OPD delivers high specific detection and fast response speed and shows only slight attenuation in photoelectric performance after exposure to air, light, and heat. Its superior performance outperforms the incumbent typical counterparts (ZnO, SnO2 , and PEIE as the CILs) from metrics of both stability and photoelectric characteristics. This finding suggests a promising strategy for stabilizing NF-OPDs by designing appropriate interface layers.

Associations With Virtual Visit Use Among Patients Receiving Radiation Therapy.

Purpose: The objective of this study was to test for patient characteristics associated with virtual versus office visits among radiation oncology patients. Methods and Materials: Using the electronic health record, we extracted encounter data and corresponding patient information for the 6 months before and 6 months of COVID-19-enabled virtual visits (October 1, 2019, to March 22, 2020 vs March 23, 2020, to September 1, 2020) at a National Cancer Institute-Designated Cancer Center. Encounters during COVID-19 were categorized as in-person or virtual visits. We compared patient demographic variables including race, age, sex, marital status, preferred language, insurance status, and tumor type during the pre-COVID-19 period as a baseline versus during the COVID-19 period. Multivariable analyses examined associations between these variables and virtual visit use. Results: We analyzed 4974 total encounters (2287 before COVID-19 and 2687 during COVID-19) for 3960 unique patients. All (100%) pre-COVID-19 encounters were in-person. During COVID-19, 21% of encounters were via virtual visits. There were no differences identified in pre- versus during-COVID-19 patient characteristics. However, we found significant differences in patient characteristics for in-person versus virtual encounters during COVID-19. On multivariable analysis, virtual visit use was less common among patients who were Black versus White (odds ratio [OR], 0.75; 95% CI, 0.57-0.99; P = .044) and not married versus married (OR, 0.76; 95% CI, 0.59-0.98; P = .037). Patients with head and neck (OR, 0.63; 95% CI, 0.41-0.97; P = .034), breast (OR, 0.36; 95% CI, 0.21-0.62; P ≤ .001), gastrointestinal/abdominal (OR, 0.31; 95% CI, 0.15-0.63; P = .001), or hematologic malignancy (OR, 0.20; 95% CI, 0.04-0.95; P = .043) diagnoses were less likely to be scheduled for virtual visits relative to patients with genitourinary malignancy. No Spanish-speaking patients engaged in a virtual visit. We did not identify differences in the insurance status or sex of patients scheduled for virtual visits. Conclusions: We found significant differences in virtual visit use by patient sociodemographic and clinical characteristics. Further investigation into implications of differential virtual visit use including social and structural determinants and subsequent clinical outcomes is indicated.

Programmed Upregulation of HSP70 by Metal-Organic Frameworks Nanoamplifier for Enhanced Microwave Thermal-Immunotherapy.

Thermotherapy can directly kill tumor cells whilst being accompanied by immune-enhancing effects. However, this immune-enhancing effect suffers from insufficient expression of immune response factors (e.g., heat shock protein 70, HSP70), resulting in no patient benefiting due to the recurrence of tumor cells after thermotherapy. Herein, a nanoengineered strategy of programmed upregulating of the immune response factors for amplifying synergistic therapy is explored. Metal-organic frameworks nanoamplifiers (teprenone/nitrocysteine@ZrMOF-NH2 @L-menthol@triphenylphosphine, GGA/CSNO@ZrMOF-NH2 -LM-TPP nanoamplifier, and GCZMT nanoamplifier) achieve excellent microwave (MW) thermal-immunotherapy by programmed induction of HSP70 expression. After intravenous administration, GCZMT nanoamplifiers target the mitochondria, and then release nitric oxide (NO) under MW irradiation. NO inhibits the growth of tumor cells by interfering with the energy supply of cells. Subsequently, under the combination of MW, NO, and GGA, HSP70 expression can be programmed upregulated, which can induce the response of cytotoxic CD4+ T cells and CD8+ T cells, and effectively activate antitumor immunotherapy. Hence, GCZMT nanoamplifier-mediated MW therapy can achieve a satisfactory therapeutic effect with the tumor inhibition of 97%. This research offers a distinctive insight into the exploitation of metal-organic frameworks nanoamplifiers for enhanced tumor therapy, which provides a new approach for highly effective cancer treatment.

Multifunctional Analog Resistance Switching of Si3N4-Based Memristors through Migration of Ag+ Ions and Formation of Si-Dangling Bonds.

With forming-free, self-rectifying, and self-compliant properties, memristors can effectively prevent themselves from experiencing leakage currents and overshoot voltages without any additional circuitry. However, the implementation of all these features in a single memristor remains a challenge. Herein, a multifunctional Si3N4-based memristor with a structure of Ag/a-SiNx/p++-Si has been fabricated, and it was demonstrated, for the first time, that the device exhibits novel analog resistance switching behaviors, such as being forming-free, self-rectifying, and self-compliant, presenting well a coexistence of volatile and nonvolatile performance of resistance switching. The multifunctional analog resistance switching could be attributed to the formation of the Si-dangling bond channel and the migration of Ag+ ions inside the a-SiNx layer. Our current results might provide an insightful understanding of the resistance switching mechanism of Si3N4-based memristors, and the device with a large on/off ratio (>103) and robust retention (>103 s) and endurance (>103 cycles) shows potential for application in crossbar synaptic array devices.

A Modified SiO2-Based Memristor with Reliable Switching and Multifunctional Synaptic Behaviors.

Dielectric SiO2 has possible uses as an active layer for emerging memory due to its high on/off ratio and low operation voltage. However, SiO2-based memory that relies on the conducting filament still has limited endurance and stability. Here, we have constructed a passivated layer of SiO2 using Ag-doped SrTiO3, which serves as a Ag ion reservoir for the control of filament formation. It is demonstrated that the modified memristor presents an excellent endurance switching and could stably be operated in an ambient environment for 20 days without visible degradation. Based on the reliable switching, the synaptic functions such as excitatory postsynaptic current, paired-pulse facilitation, transition from short-term memory to long-term memory, and potentiation/depression have also been implemented. Furthermore, a 7 × 7 pixel array made from memristors has successfully mimicked simple learning and forgetting behavior. The experimental results offer an alternative approach for SiO2-based memristors and a possibility to be applied in neuromorphic computing.

A Monoclinic V1-x-yTixRuyO2 Thin Film with Enhanced Thermal-Sensitive Performance.

Preparing the thermal-sensitive thin films with high temperature coefficient of resistance (TCR) and low resistivity by a highly compatible process is favorable for increasing the sensitivity of microbolometers with small pixels. Here, we report an effective and process-compatible approach for preparing V1-x-yTixRuyO2 thermal-sensitive thin films with monoclinic structure, high TCR, and low resistivity through a reactive sputtering process followed by annealing in oxygen atmosphere at 400 °C. X-ray photoelectron spectroscopy demonstrates that Ti4+ and Ru4+ ions are combined into VO2. X-ray diffraction, Raman spectroscopy, and transmission electron microscopy reveal that V1-x-yTixRuyO2 thin films have a monoclinic lattice structure as undoped VO2. But V1-x-yTixRuyO2 thin films exhibit no-SMT feature from room temperature (RT) to 106 °C due to the pinning effect of high-concentration Ti in monoclinic lattice. Moreover, RT resistivity of the V0.8163Ti0.165Ru0.0187O2 thin film is only one-eighth of undoped VO2 thin film, and its TCR is as high as 3.47%/°C.

Incorporating Human Factors Analysis and Classification System (HFACS) Into Analysis of Reported Near Misses and Incidents in Radiation Oncology.

PURPOSE: Human factors analysis and classification system (HFACS) is a framework for investigation into causation of human errors. We herein assess whether radiation oncology professionals, with brief training, can conduct HFACS on reported near misses or safety incidents (NMSIs) in a reliable (eg, with a high level of agreement) and practical (eg, timely and with user satisfaction) manner. METHODS AND MATERIALS: We adapted a classical HFACS framework by selecting and modifying main headings, subheadings, and nano-codes that were most likely to apply to radiation oncology settings. The final modified HFACS included 3 main headings, 8 subheadings, and 20 nano-codes. The modified HFACS was first tested in a simulated trial on 8 NMSI and was analyzed by 5 to 10 radiation oncology professionals, with 2 endpoints: (1) agreement among participants at the main-heading, subheading, and nano-code level, and (2) time to complete the analysis. We then performed a prospective trial integrating this approach into a weekly NMSI review meeting, with 10 NMSIs analyzed by 8 to 13 radiation oncology professionals with the same endpoints, while also collecting survey data on participants' satisfaction. RESULTS: In the simulated trial, agreement among participants was 85% on the main headings, 73% on the subheadings, and 70% on the nano-codes. Participants needed, on average, 16.4 minutes (standard deviation, 5.7 minutes) to complete an analysis. In the prospective trial, agreement between participants was 81% on the main headings, 75% on the subheadings, and 74% on the nano-codes. Participants needed, on average, 8.3 minutes (standard deviation, 4.7 minutes) to complete an analysis. The average satisfaction with the proposed HFACS approach was 3.9 (standard deviation 1.0) on a scale from 1 to 5. CONCLUSIONS: This study demonstrates that, after relatively brief training, radiation oncology professionals were able to perform HFACS analysis in a reliable and timely manner and with a relatively high level of satisfaction.

A high performance electroformed single-crystallite VO2 threshold switch.

Threshold switches (TSs) are an effective approach for resolving the sneak path problem within a memristor array. VO2 is a promising material for fabricating high-performance TSs. Here we report a single crystal VO2-based TS device with high switching performance. The single crystal monoclinic VO2 channel is obtained by electroforming in a composite vanadium oxide film consisting of VO2, V2O5 and V3O7. The formation mechanism on single crystal VO2 is thoroughly investigated by means of X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The single crystal VO2-based TS device exhibits better switching performance than the polycrystalline monoclinic VO2 counterpart. The TS device based on a single crystal channel with the (2[combining macron]11) orientation exhibits a steep turn-on voltage slope of <0.5 mV dec-1, a fast switching speed of 23 ns, an excellent endurance over 109 cycles, a high Ion/Ioff ratio of 143 and a low sample-to-sample variance. The enhanced switching performance originates from the single crystal feature and specified crystal orientation.

Facile Fabrication of Composite Vanadium Oxide Thin Films with Enhanced Thermochromic Properties.

In general, high-purity monoclinic VO2 (VO2(M)) was considered as a prerequisite for obtaining VO2-based thermochromic coatings with high performance. The coexistence of other vanadium oxides (such as V3O7 and V2O5) in VO2 coatings was regarded as an unfavorable issue. Here, we investigate the microstructures and thermochromic properties of the composite vanadium oxide (CVO) thin films. The results demonstrate that the proper coexistence of high valent vanadium oxides (V3O7 and V2O5) in VO2-based films can remarkably enhance the thermochromic performance of films. The CVO thin films were prepared by a room-temperature sputtering process followed by a modified rapid annealing routine in air. The structural analyses (X-ray diffraction, Raman spectroscopy, and transmission electron microscopy) reveal the coexistence of VO2(M), V3O7(M), and V2O5(O) in CVO thin films. The luminous transmittance (Tlum) and solar modulation ability (ΔTsol) of the CVO thin film obtained by an optimal preparation process are 1.93 and 1.34 times those of the pure polycrystalline VO2 thin film, respectively. Moreover, the CVO thin film exhibits lower semiconductor-to-metal transition temperature (60.8 °C) than the pure VO2(M) thin film (67.9 °C). Furthermore, the fabrication process is well-reproducible, which is highly attractive for the mass production.

Human Error Bowtie Analysis to Enhance Patient Safety in Radiation Oncology.

PURPOSE: Ensuring safety within RT is of paramount importance. To further support and augment patient safety efforts, the purpose of this research was to test and refine a robust methodology for analyzing human errors that defeat individual controls within RT quality assurance (QA) programs. METHODS: The method proposed for performing Bowtie Analysis (BTA) was based on training and recommendations from practitioners in the field of Human Factors and Ergonomics practice. Multidisciplinary meetings to iteratively develop BTA focused on incorrect site setup instructions was conducted. RESULTS: From November 2015 to February 2017, we had 12 reported incidents related to site setup notes that could have led to site setup errors. Based on this data, we conducted five BTA analyses related to incorrect site setup instructions. None of the individual controls within our QA program designed to check for potential errors with site setup instructions met the level of robustness to be classified as key safeguards or barriers. CONCLUSIONS: The relatively low number of incidents causing patient harm has led us to typically assume that we have sufficient and effective controls in place to prevent serious human errors from leading to severe patient consequences. Based on our BTA, we question how well we truly understand the details of our individual controls. To meet the level of safety achieved by high reliability organizations (HROs), we need to better ensure that our controls are as reliable and robust as we assume.

Room-Temperature Ferromagnetism in TiO2 Nanocrystals Synthesized by the Controlled Hydrolysis Procedure.

TiO2 nanocrystals were prepared by a controlled hydrolysis procedure at room temperature. The effect of V-doping, N-doping and V/N codoping on the lattice parameters and magnetic properties of TiO2 nanocrystals was investigated by means of X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and vibration sample magnetometry. Doping performed at room temperature causes the expansion of lattice parameters. Undoped and doped TiO2 nanocrystals show room-temperature ferromagnetism. A monotonic correlation between saturation magnetization and the ratio of the lattice parameter c to a (c/a) was observed. Saturation magnetization of TiO2 nanocrystals increases with the value of c/a.

Ultrasmooth and thermally stable silver-based thin films with subnanometer roughness by aluminum doping.

Rough surface and poor stability of ultrathin Ag films limit their applications in nanophotonic and optoelectronic devices. Here, we report an approach for fabricating ultrasmooth and thermally stable Ag-based thin films on SiO2/Si substrates by Al-doping. The effect of Al-doping on the surface morphology and stability of ultrathin Ag films at room temperature and elevated temperature was investigated. The 15 nm Al-doped Ag films with an Al atomic concentration of 4% have a root-mean-square roughness as low as 0.4 nm. The smooth surface morphology is maintained even after 300 °C annealing in N2. Al-doping enhances the nuclei density of films. Moreover, a capping layer spontaneously formed over the Al-doped Ag films restrains the surface diffusion and mass transportation of Ag atoms. Therefore, Al-doping induces ultrathin Ag films with highly stable and ultrasmooth surface morphology.

An ultrathin, smooth, and low-loss Al-doped Ag film and its application as a transparent electrode in organic photovoltaics.

An ultrathin, smooth, and low-loss Ag film without a wetting layer is achieved by co-depositing a small amount of Al into Ag. The film can be as thin as 6 nm, with a roughness below 1 nm and excellent mechanical flexibility. Organic photovoltaics that use these thin films as transparent electrode show superior efficiency to their indium tin oxide (ITO) counterparts because of improved photon management.

Facile preparation of micro-mesoporous carbon-doped TiO2 photocatalysts with anatase crystalline walls under template-free condition.

A new low-temperature procedure has been used for preparing micro-mesoporous carbon-doped TiO2 photocatalysts, with anatase pore wall and substitutional carbon occupying oxygen sites, which exhibit outstanding photocatalytic activity under visible light irradiation.