A high‐performance, transparent, and extremely thin (<15 nm) hydrogen (H2) gas sensor is developed using 2D electron gas (2DEG) at the interface of an Al2O3/TiO2 thin film heterostructure grown by ...atomic layer deposition (ALD), without using an epitaxial layer or a single crystalline substrate. Palladium nanoparticles (≈2 nm in thickness) are used on the surface of the Al2O3/TiO2 thin film heterostructure to detect H2. This extremely thin gas sensor can be fabricated on general substrates such as a quartz, enabling its practical application. Interestingly, the electron density of the Al2O3/TiO2 thin film heterostructure can be tailored using ALD process temperature in contrast to 2DEG at the epitaxial interfaces of the oxide heterostructures such as LaAlO3/SrTiO3. This tunability provides the optimal electron density for H2 detection. The Pd/Al2O3/TiO2 sensor detects H2 gas quickly with a short response time of <30 s at 300 K which outperforms conventional H2 gas sensors, indicating that heating modules are not required for the rapid detection of H2. A wide bandgap (>3.2 eV) with the extremely thin film thickness allows for a transparent sensor (transmittance of 83% in the visible spectrum) and this fabrication scheme enables the development of flexible gas sensors.
A high‐performance, transparent, and extremely thin (≈15 nm) hydrogen (H2) gas sensor is developed using 2D electron gas at the interface of an Al2O3/TiO2 thin film heterostructure. This extremely thin gas sensor can be fabricated on general substrates such as a glass using atomic layer deposition, and this fabrication scheme enables the development of flexible gas sensors.
Sarcopenia is associated with nonalcoholic fatty liver disease (NAFLD). This study investigated whether sarcopenia is associated with significant liver fibrosis in subjects with NAFLD. Data from the ...Korean National Health and Nutrition Examination Surveys 2008‐2011 database were analyzed. NALFD was defined by NAFLD liver fat score, comprehensive NAFLD score, or hepatic steatosis index. Degree of liver fibrosis was assessed by NAFLD fibrosis score (NFS), FIB‐4, and Forns index. Significant liver fibrosis was defined as FIB‐4 ≥2.67 and the highest quartile values of NFS and Forns index. Sarcopenia index (= total appendicular skeletal muscle mass kg/body mass index (kg/m2) was calculated using dual‐energy X‐ray absorptiometry. Using the NAFLD liver fat score, NAFLD was identified in 2761 (28.5%) of 9676 subjects. Of subjects with NAFLD, sarcopenia was identified in 337 (12.2%). Sarcopenia was significantly associated with significant liver fibrosis assessed in fibrosis prediction models (all P < 0.05). In subgroups stratified according to body mass index and homeostasis model assessment of insulin resistance, a significant association between sarcopenia and significant liver fibrosis by NFS was consistently present (odds ratio = 1.76‐2.68 depending on the subgroup, all P < 0.05). Multivariate logistic regression analysis demonstrated an independent association between SI and significant liver fibrosis by NFS after adjusting for other confounders (odds ratio = 0.52‐0.67, all P < 0.01). Other NAFLD (comprehensive NAFLD score, hepatic steatosis index) and fibrosis prediction models (FIB‐4 and Forns index) produced similar results. Conclusion: Sarcopenia is associated with significant liver fibrosis in subjects with NAFLD, and the association is independent of obesity and insulin resistance. (Hepatology 2016;63:776–786)
Abstract
Recent advances in nanomaterials and nano-microfabrication have enabled the development of flexible wearable electronics. However, existing manufacturing methods still rely on a multi-step, ...error-prone complex process that requires a costly cleanroom facility. Here, we report a new class of additive nanomanufacturing of functional materials that enables a wireless, multilayered, seamlessly interconnected, and flexible hybrid electronic system. All-printed electronics, incorporating machine learning, offers multi-class and versatile human-machine interfaces. One of the key technological advancements is the use of a functionalized conductive graphene with enhanced biocompatibility, anti-oxidation, and solderability, which allows a wireless flexible circuit. The high-aspect ratio graphene offers gel-free, high-fidelity recording of muscle activities. The performance of the printed electronics is demonstrated by using real-time control of external systems via electromyograms. Anatomical study with deep learning-embedded electrophysiology mapping allows for an optimal selection of three channels to capture all finger motions with an accuracy of about 99% for seven classes.
•Dialdehyde methylcellulose (DAMC) was synthesized from MC via periodate oxidation.•Dual-crosslinked DAMC copolymer hydrogels were obtained using chitosan oligomer.•Mechanical and self-healing ...properties of composite hydrogels were improved.•Composite hydrogels have a great potential for cosmetic applications.
Self-healing, thermo-responsive hydrogels have received increasing attention for tissue engineering, drug delivery, and cosmetic applications. Here, a thermo-responsive hydrogel with self-healing properties was prepared from methylcellulose (MC) and a water-soluble chitosan oligomer (CHI-O). First, dialdehyde methylcellulose (DAMC) derivative was synthesized from MC via periodate oxidation, and its rheological behavior was investigated according to the degree of oxidation. Next, dual-crosslinked DAMC/CHI-O copolymer hydrogels were obtained via Schiff base formation between the aldehyde group of DAMC and the amino group of CHI-O. These hydrogels were chemically linked by imine bonds and physically linked through hydrophobic interactions originating from MC. Based on rheological and compression tests, the gelation rate, mechanical properties, and self-healing properties of the copolymer hydrogels are compared with those of the MC hydrogel. Finally, the release of model compounds (adenosine and l-ascorbic acid) from the DAMC/CHI-O copolymer hydrogel was studied as a preliminary test for cosmetic applications.
Abstract
Excessive ethanol in breath can be an indicator of alcoholism and a biomarker of liver disease. Herein, we present a novel porous aluminum anodic oxide (AAO)‐based chemi‐capacitive sensor ...that can detect ppb‐levels of ethanol gas at room temperature. The oxalic acid‐based porous AAO is an amorphous material contaminated with Al(OH)
3
and C
2
O
4
2−
ions (anion‐contamination), which react with adsorbed ethanol gas. The optimal resonance frequency of ethanol was determined to be 500 Hz, and the response to 200 ppm ethanol at this frequency was 1.56%. Especially, the limit of detection of ppb‐level (16.49 ppb) was obtained. The detection range, reliability, and selectivity of the sensor, as well as its surface properties were comprehensively investigated. The proposed sensor is promising for the detection of liver disease as well as for commercial breath ethanol analyzers.
Additional surgeries for implantable biomedical devices are inevitable to replace discharged batteries, but repeated surgeries can be a risk to patients, causing bleeding, inflammation, and ...infection. Therefore, developing self‐powered implantable devices is essential to reduce the patient's physical/psychological pain and financial burden. Although wireless communication plays a critical role in implantable biomedical devices that contain the function of data transmitting, it has never been integrated with in vivo piezoelectric self‐powered system due to its high‐level power consumption (microwatt‐scale). Here, wireless communication, which is essential for a ubiquitous healthcare system, is successfully driven with in vivo energy harvesting enabled by high‐performance single‐crystalline (1 − x)Pb(Mg1/3Nb2/3)O3−(x)Pb(Zr,Ti)O3 (PMN‐PZT). The PMN‐PZT energy harvester generates an open‐circuit voltage of 17.8 V and a short‐circuit current of 1.74 µA from porcine heartbeats, which are greater by a factor of 4.45 and 17.5 than those of previously reported in vivo piezoelectric energy harvesting. The energy harvester exhibits excellent biocompatibility, which implies the possibility for applying the device to biomedical applications.
In vivo self‐powered wireless transmission using a flexible single‐crystalline piezoelectric energy harvester is demonstrated. The high‐performance energy harvester generates an output voltage of 17.8 V and a current of 1.75 µA from the contraction and relaxation motion of porcine heart. The energy from in vivo physiological motion enables self‐powered wireless transmission, thus realizing practical application in the ubiquitous healthcare system.
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•Highly porous SnO2-CuO nanocomposite hollow nanofibers were synthesized for use as a high-performance H2S gas sensor.•SnO2-CuO nanotubes were formed by electrospinning with mixed ...solutions by the Kirkendall effect.•CuO nanoparticles were homogeneously distributed within a SnO2 tubular shape.•A high response of 1395 (Ra/Rg) and a very fast response time of 5.27 s toward 5 ppm H2S gas at 200 °C.•These materials are highly promising candidates for gas sensing due to increased surface area and p-n junctions.
Highly porous SnO2-CuO hollow nanofiber mats were synthesized by electrospinning combined with thermal processing for high performance H2S gas sensing applications. The porous morphology generated in the one-dimensional (1-D) nanocomposite led to an improvement in surface-to-adsorbate molecule interactions. Our novel concept lies in fabrication of SnO2-CuO with a 1-D highly porous structure by electrospinning coupled with generation of hollow nanostructures drawing on nanofiber-to-nanotube transformation affected by Kirkendall effect during thermal processing. The fibrous structure was synthesized by electrospinning with mixed solution of Sn and Cu precursors, which then underwent heat treatment under various temperature conditions. The hollow structures were generated based on the different diffusion rates between SnO2-CuO and Sn/Cu. The SnO2-CuO nanotubes have low operating temperatures and high H2S sensing performance. The increased surface area for detecting H2S resulted in great enhancement of the response (Ra/Rg = 1395) and a very fast response time of 5.27 s with a stable recovery time to a low concentration of H2S to 5 ppm at 200 °C. The porous SnO2-CuO hollow nanofiber gas sensor proved to be a promising candidate for gas sensor systems due to increased surface area with metal oxide catalyst. The mechanisms involved in enhancement of gas response and extended applications are also discussed.
Neuropathic pain (NP) is a complex, debilitating, chronic pain state, heterogeneous in nature and caused by a lesion or disease affecting the somatosensory system. Its pathogenesis involves a wide ...range of molecular pathways. NP treatment is extremely challenging, due to its complex underlying disease mechanisms. Current pharmacological and nonpharmacological approaches can provide long-lasting pain relief to a limited percentage of patients and lack safe and effective treatment options. Therefore, scientists are focusing on the introduction of novel treatment approaches, such as stem cell therapy. A growing number of reports have highlighted the potential of stem cells for treating NP. In this review, we briefly introduce NP, current pharmacological and nonpharmacological treatments, and preclinical studies of stem cells to treat NP. In addition, we summarize stem cell mechanisms—including neuromodulation in treating NP. Literature searches were conducted using PubMed to provide an overview of the neuroprotective effects of stem cells with particular emphasis on recent translational research regarding stem cell-based treatment of NP, highlighting its potential as a novel therapeutic approach.
Abstract
In recent times, electronics have been increasingly minimized, and hence, heat dissipation has become essential. Owing to its high thermal conductivity and superior electrical insulation, ...hexagonal‐boron nitride (h‐BN) has been regarded as an appropriate ceramic material to increase the thermal conductivity of polymer nanocomposites for effective heat dissipation. However, the poor through‐plane thermal conductivity of h‐BN severely restricts its practical uses, and it is favorable for heat to radiates in the in‐plane direction. In this study, densified spherical h‐BN (sph‐BN) microspheres, composed of as‐synthesized nano‐sized h‐BN (nano‐BN), were manufactured by a spray‐drying process with variations in organic and/or inorganic binders followed by sintering. After incorporating various sph‐BN particles as fillers into polydimethylsiloxane (PDMS), the through‐plane thermal conductivity of composites embedded with sph‐BN, assisted by a sodium silicate binder, enhanced the highest through‐plane and in‐plane thermal conductivities. The composites exhibited high thermal isotropy (through‐plane thermal conductivity/in‐plane thermal conductivity: ) of 0.77. The out‐of‐plane thermal conductivity of the composites was remarkably enhanced by over 2000% compared with pristine PDMS, which can be attributed to the synergy combined with the synthesis of the densified spherical BN initiated by nano‐BN, sintering, and the application of inorganic binders. This study proposes a simple method to prepare polymer composites with h‐BN that exhibit high through‐plane thermal conductivity and are promising materials for heat removal in electronics.
Abstract The antimicrobial effects of silver (Ag) ion or salts are well known, but the effects of Ag nanoparticles on microorganisms and antimicrobial mechanism have not been revealed clearly. Stable ...Ag nanoparticles were prepared and their shape and size distribution characterized by particle characterizer and transmission electron microscopic study. The antimicrobial activity of Ag nanoparticles was investigated against yeast, Escherichia coli , and Staphylococcus aureus . In these tests, Muller Hinton agar plates were used and Ag nanoparticles of various concentrations were supplemented in liquid systems. As results, yeast and E. coli were inhibited at the low concentration of Ag nanoparticles, whereas the growth-inhibitory effects on S. aureus were mild. The free-radical generation effect of Ag nanoparticles on microbial growth inhibition was investigated by electron spin resonance spectroscopy. These results suggest that Ag nanoparticles can be used as effective growth inhibitors in various microorganisms, making them applicable to diverse medical devices and antimicrobial control systems.
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