The demand for economical and efficient data processing has led to a surge of interest in neuromorphic computing based on emerging two-dimensional (2D) materials in recent years. As a rising van der Waals (vdW) p-type Weyl semiconductor with many intriguing properties, tellurium (Te) has been widely used in advanced electronics/optoelectronics. However, its application in floating gate (FG) memory devices for information processing has never been explored. Herein, an electronic/optoelectronic FG memory device enabled by Te-based 2D vdW heterostructure for multimodal reservoir computing (RC) is reported. When subjected to intense electrical/optical stimuli, the device exhibits impressive nonvolatile electronic memory behaviors including ≈10
Two-dimensional (2D) tellurium (Te) is emerging as a promising p-type candidate for constructing complementary metal-oxide-semiconductor (CMOS) architectures. However, its small bandgap leads to a high leakage current and a low on/off current ratio. Although alloying Te with selenium (Se) can tune its bandgap, thermally evaporated SexTe1–x thin films often suffer from grain boundaries and high-density defects. Herein, we introduce a precursor-confined chemical vapor deposition (CVD) method for synthesizing single-crystalline SexTe1–x alloy nanosheets. These nanosheets, with tunable compositions, are ideal for high-performance field-effect transistors (FETs) and 2D inverters. The preformation of Se–Te frameworks in our developed CVD method plays a critical role in the growth of SexTe1–x nanosheets with high crystallinity. Optimizing the Se composition resulted in a Se0.30Te0.70 nanosheet-based p-type FET with a large on/off current ratio of 4 × 105 and a room-temperature hole mobility of 120 cm2·V–1·s–1, being eight times higher than thermally evaporated SexTe1–x with similar composition and thickness. Moreover, we successfully fabricated an inverter based on p-type Se0.30Te0.70 and n-type MoS2 nanosheets, demonstrating a typical voltage transfer curve with a gain of 30 at an operation voltage of Vdd = 3 V.
Abstract The viscosity of shear thickening fluid (STF) changes significantly with low concentrations of additives. However, existing research has suggested that there has not been any consistent enhancement mechanism of additives. The possible reason for this research gap is that existing research has focused on the effect of the shape and content of additives on shear thickening (ST) performance, whereas the friction characteristics of additives on ST performance have not been considered. Accordingly, nanoparticle‐enhanced STF with various friction characteristics of ZnO was synthesized in this study to investigate the enhancement mechanism of additives. The aspect ratio of ZnO with different shapes was obtained through SEM analysis. The friction characteristics of ZnO were examined. Lastly, the rheological behavior of reinforced STFs was evaluated. The results indicated that ST performance was enhanced compared with that of neat STF, which was significantly dependent on the friction characteristics of ZnO.
The booming market of portable and wearable electronics has aroused the requests for advanced flexible self-powered energy systems featuring both excellent performance and high safety. Herein, we report a safe, flexible, self-powered wristband system by integrating high-performance zinc-ion batteries (ZIBs) with perovskite solar cells (PSCs). ZIBs were first fabricated on the basis of a defective MnO2–x nanosheet-grown carbon cloth (MnO2–x@CC), which was obtained via the simple lithium treatment of the MnO2 nanosheets to slightly expand the interlayer spacing and generate rich oxygen vacancies. When used as a ZIB cathode, the MnO2–x@CC with a ultrahigh mass loading (up to 25.5 mg cm–2) exhibits a much enhanced specific capacity (3.63 mAh cm–2 at current density of 3.93 mA cm–2), rate performance, and long cycle stability (no obvious degradation after 5000 cycles) than those of the MnO2@CC. Importantly, the MnO2–x@CC-based quasi-solid-state ZIB not only achieves excellent flexibility and an ultrahigh energy density of 5.11 mWh cm–2 (59.42 mWh cm–3) but also presents a high safety under a wide temperature range and various severe conditions. More importantly, the flexible ZIBs can be integrated with flexible PSCs to construct a safe, self-powered wristband, which is able to harvest light energy and power a commercial smart bracelet. This work sheds light on the development of high-performance ZIB cathodes and thus offers a good strategy to construct wearable self-powered energy systems for wearable electronics.
A novel Non-Isolated-Pentagon-Rule (non-IPR) isomer of thorium-based endohedral mono-metallofullerenes (mono-EMFs), Th@C1(17418)-C76, was successfully synthesized and characterized using MALDI-TOF mass spectroscopy, single-crystal X-ray diffraction, UV-vis-NIR spectroscopy, and Raman spectroscopy. The molecular structure of this non-IPR isomer was determined unambiguously as Th@C1(17418)-C76 using a single-crystal X-ray diffraction analysis. The crystallographic results further revealed that the optimal Th site resided at the intersection of two adjacent pentagons, similar to that of U@C1(17418)-C76. Additionally, the UV-vis-NIR spectra of Th@C1(17418)-C76 exhibited distinct differences compared to the previously reported U@C1(17418)-C76, highlighting the distinctive electronic structure of actinium-based endohedral metallofullerenes (EMFs). The Raman spectrum of Th@C1(17418)-C76 exhibited similarities to that previously reported for thorium-based EMFs, indicating the analogous strong metal–cage interactions of thorium-based EMFs.
The lack of stable p-type van der Waals (vdW) semiconductors with high hole mobility severely impedes the step of low-dimensional materials entering the industrial circle. Although p-type black phosphorus (bP) and tellurium (Te) have shown promising hole mobilities, the instability under ambient conditions of bP and relatively low hole mobility of Te remain as daunting issues. Here we report the growth of high-quality Te nanobelts on atomically flat hexagonal boron nitride (h-BN) for high-performance p-type field-effect transistors (FETs). Importantly, the Te-based FET exhibits an ultrahigh hole mobility up to 1370 cm2 V-1 s-1 at room temperature, that may lay the foundation for the future high-performance p-type 2D FET and metal-oxide-semiconductor (p-MOS) inverter. The vdW h-BN dielectric substrate not only provides an ultra-flat surface without dangling bonds for growth of high-quality Te nanobelts, but also reduces the scattering centers at the interface between the channel material and the dielectric layer, thus resulting in the ultrahigh hole mobility .
Although 2D materials are widely explored for data storage and neuromorphic computing, the construction of 2D material-based memory devices with optoelectronic responsivity in the short-wave infrared (SWIR) region for in-sensor reservoir computing (RC) at the optical communication band still remains a big challenge. In this work, an electronic/optoelectronic memory device enabled by tellurium-based 2D van der Waals (vdW) heterostructure is reported, where the ferroelectric CuInP2 S6 and tellurium channel endow this device with both the long-term potentiation/depression by voltage pulses and short-term potentiation by 1550 nm laser pulses (a typical wavelength in the conventional fiber optical communication band). Leveraging the rich dynamics, a fully memristive in-sensor RC system that can simultaneously sense, decode, and learn messages transmitted by optical fibers is demonstrated. The reported 2D vdW heterostructure-based memory featuring both the long-term and short-term memory behaviors using electrical and optical pulses in SWIR region has not only complemented the wide spectrum of applications of 2D materials family in electronics/optoelectronics but also paves the way for future smart signal processing systems at the edge.
BACKGROUND More than 6 million children in the United States have asthma and greater than 20% are clinically obese. Youth with asthma and obesity are susceptible to poor health outcomes, including greater asthma symptoms severity and hospitalizations, reduced physical activity, and poorer quality of life. Mobile health technologies can increase access to chronic disease self-management interventions and family members can be powerful influencers given their substantial direct and indirect control over a child’s behavior and home environment. OBJECTIVE The Mobile Childhood and Asthma Management Program (mCHAMP) is based on the in-person CHAMP behavioral family intervention pilot trial of school-age children with asthma and obesity. In the current study, we translated the CHAMP content into digital content and conducted summative testing to measure usability, learnability, and efficiency of the mCHAMP application (app). METHODS Overall, we applied a sequential mixed-methods approach. The mCHAMP app targeted adult caregivers of children living with asthma and obesity between the ages of 6 and 12 years old. A Consumer-centered Participatory Design framework was used to guide identifying user requirements and conducting summative usability testing. While the mCHAMP app is primarily caregiver facing it is intended to connect caregivers to registered nurse (RN) interventionists. Therefore, we sought feedback from RNs as key stakeholders. RESULTS Caregivers (n=10) were female (100%), mostly African American (80%), and half had an annual household income <$25,000; most of their children (60%) were in the 99th BMI percentile. Post-Study e-Health Usability Questionnaire scores indicated high overall satisfaction, usefulness, and quality of the mCHAMP app. Most caregivers (n=7) were able to complete all 15 tasks across the six modules with two or fewer hints. The average total time to complete all tasks was 17 minutes (SD=3.9, Range=11.4–24.1). Most caregivers wanted information in static form but also preferred alternatives (e.g., audio and/or video) to support flexibility with consuming the content. Caregivers expressed the need for more child facing content as well as tailored decision support related to diet and exercise. RNs (n=5) strongly endorsed their role and use of the mCHAMP app to promote self-management among caregivers of children with obesity and asthma. They noted the importance of integrating the mCHAMP app to a local electronic health record and existing workflows. CONCLUSIONS Caregivers expressed a desire for an intervention that was easy to use and could integrate into their busy family lives. We met this expectation based on the usability, learnability, and efficiency results of our testing. The mCHAMP app has the potential to increase self-management for parents and pediatric asthma patients with multimorbidity which could improve patient and health system outcomes. The use of mCHAMP may also enable novel clinical outcomes studies based on patient reported data from the app. INTERNATIONAL REGISTERED REPORT RR2-10.2196/13549
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