Large-Scale Assembly of Peptide-Based Hierarchical Nanostructures and Their Antiferroelectric Properties.

An effective strategy is developed to create peptide-based hierarchical nanostructures through the meniscus-driven self-assembly in a large area and fabricate antiferroelectric devices based on these nanostructures for the first time. The diphenylalanine hierarchical nanostructures (FF-HNs) are self-assembled by vertically pulling a substrate from a diphenylalanine (FF) solution dissolved in a miscible solvent under precisely controlled conditions. Owing to the unique structural properties of FF nanostructures, including high crystallinity and α-helix structures, FF-HNs possess a net electrical dipole moment, which can be switched in an external electric field. The mass production of antiferroelectric devices based on FF-HNs can be successfully achieved by means of this biomimetic assembly technique. The devices show an evident antiferroelectric to ferroelectric transition under dark conditions, while the ferroelectricity is found to be tunable by light. Notably, it is discovered that the modulation of antiferroelectric behaviors of FF-HNs under glutaraldehyde exposure is due to the FF molecules that are transformed into cyclophenylalanine by glutaraldehyde. This work provides a stepping stone toward the mass production of self-assembled hierarchical nanostructures based on biomolecules as well as the mass fabrication of electronic devices based on biomolecular nanostructures for practical applications.

Electroluminescent soft elastomer actuators with adjustable luminance and strain.

We demonstrate a multifunctional soft actuator that exhibits both electroluminescence (EL) and soft actuation with a strain of 85% and a maximum luminance of 300 cd m-2, superior to previous devices with individual functions. This was possible by combining several strategies such as the development of highly conductive, transparent, and stretchable electrodes, incorporation of high-k nanoparticles to increase the electric field applied to the EL particles, and application of AC + DC composite signals to simplify the device structure. We expect this research to contribute to the development of new soft devices that can further enhance human-machine interactions in color displaying actuator applications.

Highly sensitive and flexible strain sensors based on patterned ITO nanoparticle channels.

We demonstrate a highly sensitive and flexible bending strain sensor using tin-doped indium oxide (ITO) nanoparticles (NPs) assembled in line patterns on flexible substrates. By utilizing transparent ITO NPs without any surface modifications, we could produce strain sensors with adjustable gauge factors and optical transparency. We were able to control the dimensional and electrical properties of the sensors, such as channel height and resistance, by controlling the NP assembly speed. Furthermore, we were able to generate controlled gauge factor with values ranging from 18 to 157, which are higher than previous cases using metallic Cr NPs and Au NPs. The alignment of the ITO NPs in parallel lines resulted in low crosstalk between the transverse and longitudinal bending directions. Finally, our sensor showed high optical transmittance, up to ∼93% at 500 nm wavelength, which is desirable for flexible electronic applications.

Carbon and metal nanotube hybrid structures on graphene as efficient electron field emitters.

We report a facile and efficient method for the fabrication of highly-flexible field emission devices by forming tubular hybrid structures based on carbon nanotubes (CNTs) and nickel nanotubes (Ni NTs) on graphene-based flexible substrates. By employing an infiltration process in anodic alumina oxide (AAO) templates followed by Ni electrodeposition, we could fabricate CNT-wrapped Ni NT/graphene hybrid structures. During the electrodeposition process, the CNTs served as Ni nucleation sites, resulting in a large-area array of high aspect-ratio field emitters composed of CNT-wrapped Ni NT hybrid structures. As a proof of concepts, we demonstrate that high-quality flexible field emission devices can be simply fabricated using our method. Remarkably, our proto-type field emission devices exhibited a current density higher by two orders of magnitude compared to other devices fabricated by previous methods, while maintaining its structural integrity in various bending deformations. This novel fabrication strategy can be utilized in various applications such as optoelectronic devices, sensors and energy storage devices.

Acupuncture for acute postoperative pain after back surgery: a systematic review and meta-analysis of randomized controlled trials.

OBJECTIVES: Acupuncture is commonly used as a complimentary treatment for pain management. However, there has been no systematic review summarizing the current evidence concerning the effectiveness of acupuncture for acute postoperative pain after back surgery. This systematic review aimed at evaluating the effectiveness of acupuncture treatment for acute postoperative pain (≤1 week) after back surgery. METHODS: We searched 15 electronic databases without language restrictions. Two reviewers independently assessed studies for eligibility and extracted data, outcomes, and risk of bias. Random effect meta-analyses and subgroup analyses were performed. RESULTS: Five trials, including 3 of high quality, met our inclusion criteria. The meta-analysis showed positive results for acupuncture treatment of pain after surgery in terms of the visual analogue scale (VAS) for pain intensity 24 hours after surgery, when compared to sham acupuncture (standard mean difference -0.67 (-1.04 to -0.31), P = 0.0003), whereas the other meta-analysis did not show a positive effect of acupuncture on 24-hour opiate demands when compared to sham acupuncture (standard mean difference -0.23 (-0.58 to 0.13), P = 0.21). CONCLUSION: Our systematic review finds encouraging but limited evidence for the effectiveness of acupuncture treatment for acute postoperative pain after back surgery. Further rigorously designed clinical trials are required.

Graphene-based materials functionalized with elastin-like polypeptides.

Graphene-based materials commonly require functionalization for biological applications in order to control their physical/colloidal properties and to introduce additional capabilities, such as stimuli-responsiveness and affinity to specific biomolecules. Here, we functionalized CVD-grown graphene and graphene oxide with a genetically engineered elastin-like polypeptide fused to a graphene binding peptide and then showed that the resulting hybrid materials exhibit thermo- and photoresponsive behaviors. Furthermore, we demonstrate that our genetic engineering strategy allows for the facile introduction of bioactivity to reduced graphene oxide. The stimuli-responsiveness and genetic tunability of our graphene-protein nanocomposites are attractive for addressing future biomedical applications.

Observation of localized strains on vertically grown single-walled carbon nanotube forests via polarized Raman spectroscopy.

Vertically grown single-walled carbon nanotube (V-SWCNT) forests, synthesized by water-assisted plasma-enhanced chemical vapor deposition, were studied using polarized micro-Raman spectroscopy. Among three different sections (root, center and end) along the vertical growth direction, the degree of V-SWCNT alignment was highest in the center section. Raman frequency red-shifts up to 7 and 13 cm(-1), for RBM and G-band, respectively, were observed in the center section, with respect to the Raman frequencies measured in the root and the end sections. Raman frequency downshift and concurrent linewidth broadening of the G-band, revealing a localized strain, were also observed in the center section. The existence of a localized strain in the center section of the V-SWCNT was further confirmed by observing a strong polarization anisotropy of up to 8 cm(-1) in the G-band Raman frequency for different polarized Raman scattering configurations at the same probed spot.

Gold-Nanolayer-Derived Zincophilicity Suppressing Metallic Zinc Dendrites and Its Efficacy in Improving Electrochemical Stability of Aqueous Zinc-Ion Batteries.

Herein, an Au-coating layer adjusted on the surface of a Zn metal electrode that effectively suppresses the dendrite growth as well as the mechanisms underlying the dendrite suppression as a result of the zincophilic character of Au is introduced. For the Au-coated Zn metal symmetric cell, uniform deposition of Zn-derived compounds was revealed by operando synchrotron tomography. Microscopic studies demonstrate that the Au-coating layer is induced to form a new Zn-Au alloy during the initial Zn deposition, resulting in stabilized long-term stripping/plating of Zn via the 'embracing effect' that intimately accommodates Zn deposition for further cycles. This property supports the successful operation of symmetrical cells up to 50 mA cm-2 . According to Zn electrodeposition simulation, it is verified that the suppression of dendrite growth is responsible for the electro-conducting Au nanolayer that uniformly distributes the electric field and protects the Zn electrode from corrosion, ultimately promoting uniform Zn growth. The compatibility of the Au-coating layer for full cell configuration is verified using NaV3 O8 as a cathode material over 1 000 cycles. This finding provides a new pathway for the enhancement of the electrochemical performance of ZIBs by suppressing the dendritic growth of Zn by means of a zincophilic Au nanolayer.

A Review of Rechargeable Zinc-Air Batteries: Recent Progress and Future Perspectives.

Zinc-air batteries (ZABs) are gaining attention as an ideal option for various applications requiring high-capacity batteries, such as portable electronics, electric vehicles, and renewable energy storage. ZABs offer advantages such as low environmental impact, enhanced safety compared to Li-ion batteries, and cost-effectiveness due to the abundance of zinc. However, early research faced challenges due to parasitic reactions at the zinc anode and slow oxygen redox kinetics. Recent advancements in restructuring the anode, utilizing alternative electrolytes, and developing bifunctional oxygen catalysts have significantly improved ZABs. Scientists have achieved battery reversibility over thousands of cycles, introduced new electrolytes, and achieved energy efficiency records surpassing 70%. Despite these achievements, there are challenges related to lower power density, shorter lifespan, and air electrode corrosion leading to performance degradation. This review paper discusses different battery configurations, and reaction mechanisms for electrically and mechanically rechargeable ZABs, and proposes remedies to enhance overall battery performance. The paper also explores recent advancements, applications, and the future prospects of electrically/mechanically rechargeable ZABs.

Multilayered nano-prism vertex tips for tip-enhanced Raman spectroscopy and imaging.

We presented a scalable fabrication method for the preparation of multilayered nano-prism vertex (NV)-tips whose dimensions can be controlled for tip-enhanced Raman spectroscopy (TERS). The NV-tip had sharp vertices (diameter ~20 nm) originated from the chemical lift-off process after the angle-grinding process, enabling high resolution imaging. TERS measurements were performed on brilliant cresyl blue (BCB) molecules using a Ag/Au NV-tip, revealing the enhanced field localization at the vertices of the NV-tip. Furthermore, we could observe the polarization effect of the NV-tip. Our NV-tips should be a powerful tool for basic research on TERS experiments and SPM applications.

Apamin attenuated cerulein-induced acute pancreatitis by inhibition of JNK pathway in mice.

BACKGROUND/AIM: We have previously reported that bee venom (BV) has a protective role against acute pancreatitis (AP). However, the effects of apamin, the major compound of BV, on AP have not been determined. The aim of this study was to evaluate the effects of apamin on cerulein-induced AP. METHODS: AP was induced via intraperitoneal injection of supramaximal concentrations of the stable cholecystokinin analogue cerulein (50 µg/kg) every hour for 6 times. In the apamin treatment group, apamin was administered subcutaneously (10, 50, or 100 µg/kg) at both 18 and 1 h before the first cerulein injection. The mice were sacrificed at 6 h after the final cerulein injection. Blood samples were obtained to determine serum amylase and lipase levels, as well as cytokine production. The pancreas and lung were rapidly removed for morphologic and histological examination, myeloperoxidase (MPO) assay, and real-time reverse transcription-polymerase chain reaction. Furthermore, we isolated the pancreatic acinar cells to specify the role of apamin in AP. RESULTS: Pre-treatment with apamin inhibited histological damage, pancreatic weight/body weight ratio, serum level of amylase and lipase, MPO activity, and cytokine production. In addition, apamin treatment significantly inhibited cerulein-induced pancreatic acinar cell death. Furthermore, apamin treatment inhibited the cerulein-induced activation of c-Jun NH2-terminal kinases (JNK). CONCLUSIONS: These results could suggest that apamin could protect against AP by inhibition of JNK activation.

Nanotube-bridged wires with sub-10 nm gaps.

We report a simple but efficient method to synthesize carbon nanotube-bridged wires (NBWs) with gaps as small as 5 nm. In this method, we have combined a strategy for assembling carbon nanotubes (CNTs) inside anodized aluminum oxide pores and the on-wire lithography technique to fabricate CNT-bridged wires with gap sizes deliberately tailored over the 5-600 nm range. As a proof-of-concept demonstration of the utility of this architecture, we have prepared NBW-based chemical and biosensors which exhibit higher analyte sensitivity (lower limits of detection) than those based on planar CNT networks. This observation is attributed to a greater surface-to-volume ratio of CNTs in the NBWs than those in the planar CNT devices. Because of the ease of synthesis and high yield of NBWs, this technique may enable the further incorporation of CNT-based architectures into various nanoelectronic and sensor platforms.

High-performance photoconductive channels based on (carbon nanotube)-(CdS nanowire) hybrid nanostructures.

A photoconductive channel based on hybrid nanostructures comprising carbon nanotubes (CNTs) and CdS nanowires is fabricated by a directed assembly strategy and catalyst-assisted chemical vapor deposition (CVD). The photoconductive channels simultaneously exhibit large photocurrent and fast response speed. Furthermore, it can be easily applied to surfaces that are not flat, such as a glass tube. This is a simple but efficient strategy for various optoelectronic applications.

Reply to comment on 'Metallic nanowire-graphene hybrid nanostructures for highly flexible field emission devices'.

In our previous paper (Arif et al 2011 Nanotechnology 22 355709), we developed a method to prepare metallic nanowire-graphene hybrid nanostructures and applied it to the fabrication of flexible field emission devices. For the quantitative analysis of the devices, the basic Fowler-Nordheim model was used. However, as pointed out by Forbes (2012 Nanotechnology 23 288001) the basic Fowler-Nordheim model should be corrected when the quantum confinement effect and the screening effect are considered. Forbes also developed a method that checks quantitatively the consistency between the experimental data and the theoretical assumptions. These discussions should provide an important theoretical framework in the quantitative analysis of our devices as well as large area field emitters in general.

Bias-Modified Schottky Barrier Height-Dependent Graphene/ReSe2 van der Waals Heterostructures for Excellent Photodetector and NO2 Gas Sensing Applications.

Herein, we reported a unique photo device consisting of monolayer graphene and a few-layer rhenium diselenide (ReSe2) heterojunction. The prepared Gr/ReSe2-HS demonstrated an excellent mobility of 380 cm2/Vs, current on/off ratio ~ 104, photoresponsivity (R ~ 74 AW-1 @ 82 mW cm-2), detectivity (D* ~ 1.25 × 1011 Jones), external quantum efficiency (EQE ~ 173%) and rapid photoresponse (rise/fall time ~ 75/3 µs) significantly higher to an individual ReSe2 device (mobility = 36 cm2 V-1s-1, Ion/Ioff ratio = 1.4 × 105-1.8 × 105, R = 11.2 AW-1, D* = 1.02 × 1010, EQE ~ 26.1%, rise/fall time = 2.37/5.03 s). Additionally, gate-bias dependent Schottky barrier height (SBH) estimation for individual ReSe2 (45 meV at Vbg = 40 V) and Gr/ReSe2-HS (9.02 meV at Vbg = 40 V) revealed a low value for the heterostructure, confirming dry transfer technique to be successful in fabricating an interfacial defects-free junction. In addition, HS is fully capable to demonstrate an excellent gas sensing response with rapid response/recovery time (39/126 s for NO2 at 200 ppb) and is operational at room temperature (26.85 °C). The proposed Gr/ReSe2-HS is capable of demonstrating excellent electro-optical, as well as gas sensing, performance simultaneously and, therefore, can be used as a building block to fabricate next-generation photodetectors and gas sensors.

A Wide Bandgap Halide Perovskite Based Self-Powered Blue Photodetector with 84.9% of External Quantum Efficiency.

A self-powered, color-filter-free blue photodetector (PD) based on halide perovskites is reported. A high external quantum efficiency (EQE) of 84.9%, which is the highest reported EQE in blue PDs, is achieved by engineering the A-site monovalent cations of wide-bandgap perovskites. The optimized composition of formamidinium (FA)/methylammonium (MA) increases the heat of formation, yielding a uniform and smooth film. The incorporation of Cs+ ions into the FA/MA composition suppresses the trap density and increases charge-carrier mobility, yielding the highest average EQE of 77.4%, responsivity of 0.280 A W-1 , and detectivity of 5.08 × 1012 Jones under blue light. Furthermore, Cs+ improves durability under repetitive operations and ambient atmosphere. The proposed device exhibits peak responsivity of 0.307 A W-1 , which is higher than that of the commercial InGaN-based blue PD (0.289 A W-1 ). This study will promote the development of next-generation image sensors with vertically stacked perovskite PDs.

Metallic nanowire-graphene hybrid nanostructures for highly flexible field emission devices.

We report a simple but efficient method to prepare metallic nanowire-graphene (MN-G) hybrid nanostructures at a low temperature and show its application to the fabrication of flexible field emission devices. In this method, a graphene layer was transferred onto an anodic alumina oxide template, and vertically aligned Au nanowires were grown on the graphene surface via electrodeposition method. As a proof of concept, we demonstrated the fabrication of flexible field emission devices, where the MN-G hybrid nanostructures and another graphene layer on PDMS substrates were utilized as a cathode and an anode for highly flexible devices, respectively. Our field emission device exhibited stable and high field emission currents even when bent down to the radius of curvature of 25 mm. This MN-G hybrid nanostructure should prove tremendous flexibility for various applications such as bio-chemical sensors, field emission devices, pressure sensors and battery electrodes.

Hot Electron Tunneling in Pt/LaAlO3/SrTiO3 Heterostructures for Enhanced Photodetection.

LaAlO3/SrTiO3 (LAO/STO) heterostructures, in which a highly mobile two-dimensional electron gas (2DEG) is formed, have great potential for optoelectronic applications. However, the inherently high density of the 2DEG hinders the observation of photo-excitation effects in oxide heterostructures. Herein, a strong photoresponse of the 2DEG in a Pt/LAO/STO heterostructure is achieved by adopting a vertical tunneling configuration. The tunneling of the 2DEG through an ultrathin LAO layer is significantly enhanced by UV light irradiation, showing a maximum photoresponsivity of ∼1.11 × 107%. The strong and reversible photoresponse is attributed to the thermionic emission of photoexcited hot electrons from the oxygen-deficient STO. Notably, the oxygen vacancy defects play a critical role in enhancing the tunneling photocurrent. Our systematic study on the hysteresis behavior and the light power dependency of the tunneling current consistently support the fact that the photoexcited hot electrons from the oxygen vacancies strongly contribute to the tunneling conduction under the UV light. This work offers valuable insights into a novel photodetection mechanism based on the 2DEG as well as into developing ultrathin optoelectronic devices based on the oxide heterostructures.

Association of thyroid autoantibodies with moyamoya-type cerebrovascular disease: a prospective study.

BACKGROUND AND PURPOSE: To investigate the association between thyroid autoantibodies and moyamoya disease (MMD) in patients with an apparent euthyroid state. METHODS: We prospectively studied angiographically diagnosed patients with MMD. We compared demographic profiles, thyroid function test, and thyroid autoantibody status between MMD and control groups. RESULTS: A total of 63 patients with MMD, 71 patients with non-MMD stroke, and 200 healthy control subjects were included. The prevalence of elevated thyroid autoantibodies was higher in the MMD group than in other groups (P<0.01 for MMD versus non-MMD; P<0.001 for MMD versus control subjects). After adjusting for covariates, the elevated thyroid autoantibodies (OR, 4.871; 95% CI, 1.588 to 15.277) and smoking habits (OR, 0.206 for current smoker; 95% CI, 0.054 to 0.786) were independently associated with MMD versus non-MMD stroke. CONCLUSIONS: Elevated thyroid autoantibodies were frequently observed in patients with MMD. The results of the present study suggest that immune aberrancies associated with or underlying thyroid autoimmunity are also playing a role in developing MMD.

Large-scale assembly of highly flexible low-noise devices based on silicon nanowires.

Recently, integrated flexible devices based on silicon nanowires (Si-NWs) have received significant attention as high performance flexible devices. However, most previous assembly methods can generate only specifically-shaped devices and require unconventional facilities, which has been a major hurdle for industrial applications. Herein, we report a simple but very efficient method for assembling Si-NWs into virtually generally-shape patterns on flexible substrates using only conventional microfabrication facilities, allowing us to mass-produce highly flexible low-noise devices. As proof of this method, we demonstrated the fabrication of highly bendable top-gate transistors based on Si-NWs. These devices showed typical n-type semiconductor behaviors, and exhibited a much lower noise level compared to previous flexible devices based on organic conductors or other nanowires. In addition, the gating behaviors and low-noise characteristics of our devices were maintained, even under highly bent conditions.