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Wearable energy storage system must maintain robust electrochemical performance under severe mechanical and chemical deformations. Here, we demonstrate wearable supercapacitor system assembled with electrodes composed of one-step carbonized plant epidermis and gelatin based hydrogel electrolyte which possesses high electrochemical performance and superior reliability under ambient condition. The carbonized mulberry paper (MP) was used as an electrode to achieve improved volumetric energy density as well as mechanical-chemical reliability (e.g. mechanical toughness and acid resistance). Rationally designed active materials composed of vertically grown WO 3 NRs and reduced graphene oxide (rGO) anchored on MP, were employed for developing organism epidermis based supercapacitor. Such electrode exhibits high volumetric energy and power densities of 30.28 mWh cm−3 and 7.67 W cm−3, retaining the volumetric capacitance of 96.0% even after 110,000 charge-discharge cycles. As the final step, we employed the gelatin based electrolyte with high ionic conductivity to solve evaporation and leakage problems of conventional electrolytes. Organism epidermis based supercapacitor integrated with hydrogel electrolyte showed high electrochemical performance and long-term stability under ambient condition even after exposure to acid, demonstrating its gareat suitability as a large-scale wearable energy storage system. We demonstrate wearable supercapacitor system assembled with electrodes composed of one-step carbonized plant epidermis and gelatin based hydrogel electrolyte which possesses high electrochemical performance and superior reliability under ambient condition. Organism epidermis based supercapacitor integrated with hydrogel electrolyte showed high electrochemical performance and long-term stability under ambient condition even after exposure to acid, demonstrating its great suitability as a large-scale wearable energy storage system. [Display omitted] • We maximized areal and volumetric electrochemical performance (energy & power densities) and mechanical/chemical toughness through carbonized mulberry paper integrated with reduced graphene oxide (rGO) layer. Mulberry fibers inherently show excellent mechanical flexibility and acid resistance, since they have lower portion of lignin cellulose (~40%) compared with conventional paper fiber. However, electrochemically inactive mulberry fiber exhibits still low areal/volumetric energy densities and electrochemical reliability. Thus, we used carbonized mulberry paper as a substrate and electrode in this study, which was maximized for volumetric energy/power densities and mechanical/chemical toughness. • We have designed the plant-root inspired active materials structure with excellent electrochemical reliability and performances. Inspired from plant-root, we synthesized active materials structure by one-step reduction heat treatment, where WO 3 nanorods (NRs) vertically grow within the spaces of rGO and are anchored as strongly as plant-root on the carbonized mulberry fibers. The anchored structure can effectively maintain electrochemical performance and flexibility of carbonized paper by preventing delamination of WO 3 NRs even without protection layer. WO 3 NRs anchored carbonized mulberry paper (thickness 110 µm) with rGO layer exhibits volumetric capacitance retention of 96% for 110,000 cycles. In addition, maximum volumetric energy and power densities were increased to 30.28 mWh cm−3 and 7.67 W cm−3 (improvement of 220%). • Conventional liquid and gel-type electrolyte have critical issues including evaporation under ambient condition and leakage under mechanical bending-twisting deformation. Such problems are main causes of rapid electrochemical performance degradation. In our work, gelatin based hydrogel electrolyte extracted from porcine skin was integrated with electrode, in order to fabricate wearable energy storage system that is capable of operating in ambient conditions. The gelatin based hydrogel electrolyte can retain water contents and high ionic conductivity under ambient condition over 2 weeks. Ionic conductivity maintained 90.3% (228 mS cm−1) after two weeks of exposure to ambient condition, and the moisture content was maintained 98.0%. • We further extended organism epidermis based supercapacitor to large-scale application capable of operation in ambient condition. High hydrophilicity of mulberry paper enables the uniform deposition of precursor material for growth of WO 3 , i.e, WO 3 precursor, that is dispersed in the aqueous solution. As a result, GO and WO 3 precursor were uniformly deposited on large-area electrode with 9, 25, 49 cm2 followed by carbonization, resulting in the fabrication of large-scale organism epidermis based supercapacitor. [ABSTRACT FROM AUTHOR]

Background When considering various risk factors such as age, comorbidities, and complications related to the surgical procedure itself, open surgery in degenerative spinal stenosis is likely to cause more complications. Here, we report the surgical procedure and preliminary clinical results of percutaneous endoscopic stenosis lumbar decompression (PESLD) technique using a uniportal-contralateral approach for bilateral decompression of degenerative spinal stenosis. Materials and Methods Electronic medical records of 48 consecutive patients who were treated between January 2016 and August 2016 were reviewed retrospectively. All patient received PESLD through the uniportal–contralateral approach. We analyzed the outcomes using the visual analogue scale, Macnab criteria, Oswestry Disability Index, and complication rate. Results There were 48 cases (15 men, 33 women). Mean age of patients was 62.44 ± 8.68 years. Mean symptom duration was 20.13 ± 16.87 months. Neurogenic intermittent claudication was 550 m on average. Follow-up period was 7.75 ± 2.28 months (range, 5–13 months). Visual analogue scale and Oswestry Disability Index decreased significantly ( P < 0.001) and decreased by 1.073 and 5.795 odds ratio, respectively, in contralateral foraminotomy cases. Macnab outcome grade was good to excellent in 96% of patients. Dural tear occurred in 3 cases (6.25%), and 2 cases (4.17%) required transforaminal lumbar interbody fusion operation after this procedure. Conclusions The preliminary result of this uniportal–contralateral PESLD technique is encouraging (96% demonstrated a good-to-excellent outcome), and the procedure is safe. However, we need long-term follow-up and a more detailed study for more accurate results of this technique. [ABSTRACT FROM AUTHOR]

[Display omitted] • The WO x -incorporated Pt/Al 2 O 3 catalysts were synthesized by sequential impregnation. • DFT calculation confirmed the enhanced catalytic activity of the WO x -incorporated Pt/Al 2 O 3. • The activity of WO x -incorporated Pt/Al 2 O 3 was strongly affected by impregnation sequence. This study focused on the development of catalysts for the dehydrogenation of perhydro-dibenzyltoluene (H 18 -DBT) and perhydro-benzyltoluene (H 12 -BT), which are promising liquid organic hydrogen carriers (LOHCs). The reaction was performed at a low temperature to ensure hydrogen purity and catalyst durability, and the incorporation of WO x into Pt/Al 2 O 3 was investigated to improve the low-temperature activity of the Pt/Al 2 O 3 catalyst. WO x -incorporated Pt/Al 2 O 3 catalysts with superior performance compared to that of the Pt/Al 2 O 3 catalyst were developed by controlling the amount of incorporated WO x and the impregnation sequence of metals during catalyst preparation. TEM, chemisorption, and XPS analyses assisted in confirming the changes in the structure and electron density of the active material in accordance with the impregnation sequence and the amount of incorporated WO x ; moreover, these factors were found to influence the catalyst performance. The electron-donating ability of W was determined according to the impregnation sequence of the metals, and confirmed by XPS analysis and the experimental reaction results. A DFT study on a hypothetical model containing WO x confirmed the donation of electrons from W to Pt, which was consistent with the experimental results. In addition, the H 12 -BT dehydrogenation on the investigated catalyst was kinetically more favorable compared to that on the Pt/Al 2 O 3 catalyst, resulting in an enhancement of the dehydrogenation activity. [ABSTRACT FROM AUTHOR]

• Novel all-carbon fiber-based NO 2 sensor was fabricated for reliable environmental monitoring. Both RGO fiber and CNT fiber were synthesized by wet-spinning process, which is facile and compatible with large-scale production. • Unique sensing architectures of 1D graphene fiber were achieved with nitrogen doping for NO 2 sensors. Highly conductive nitrogen-doped reduced graphene oxide (RGO) fiber was achieved with wrinkled surface morphology. • CNT fibers were firstly demonstrated as heating networks for reversible NO 2 reaction. The CNT fibers with high electrical conductivity and mechanical stability are suitable for heating element to control the operating temperature of sensor. All-carbon fiber-based chemiresistor is fabricated by assembling reduced graphene oxide (RGO) fiber and carbon nanotube (CNT) fiber as reversible NO 2 sensing layer and flexible heater, respectively. Both graphene oxide (GO) and CNT fibers were synthesized by wet-spinning technique facilitating lyotropic nematic liquid crystal (LC) property. Randomly entangled CNT fiber-based heater, which is embedded in one surface of colorless polyimide (cPI) film with thickness of ˜200 μm, exhibits high bending stability and heating property up to 100 °C. Single reduced graphene oxide (RGO) fiber obtained after heat treatment at 900 °C in H 2 /N 2 ambient was integrated on the CNT fiber-embedded cPI heater, thereby establishing a new type of all-carbon fiber sensing platform. As a result, accelerated NO 2 adsorption and desorption kinetics were achieved with RGO fiber at an elevated temperature. In particular, a 9.22-fold enhancement in desorption kinetic (k des = 8.85 × 10–3 s–1) was observed at 100 °C compared with the desorption kinetic (k des = 0.96 × 10–3 s–1) at 50 °C, which was attributed to the effective heating by CNT fiber networks. This work pioneered a research on the use of emerging carbonaceous fibers for potential application in wearable chemical detectors. [ABSTRACT FROM AUTHOR]

Semiconducting metal oxides (SMOs) based gas sensors are inherently hampered by requirement of high working temperature because of their wide bandgaps. Consequently, there are remain challenges to utilize SMOs based gas sensors with regard to continuous gas monitoring platform with low power consumption. To address the inherent limitation, nitridation (i.e., N doping) of WO 3 NFs to WO x N y NFs was herein introduced for realization of low-temperature NO 2 sensing. Importantly, nitridation was conducted at intervals of 50 °C from 400 to 600 °C to adjust the degree of phase transition from semiconducting WO 3 to conductive WON phases. To further optimize the conductivity and improve the sensing characteristics, i.e., reduction of optimal operating temperature and enhancement of sensitivity, WO x N y NFs were functionalized with platinum (Pt) catalytic nanoparticles (NPs) by physical mixing. Pt NPs functionalized WO x N y NFs nitrided at 550 °C exhibited improved normalized resistance change and superior selectivity against C 2 H 5 OH, C 7 H 8 , CH 4 , CO, NH 3 , and NO at 50 °C. The noble metal catalyst–metal oxynitride hybrid system is suggested as an effective NO 2 sensing platform for low-temperature chemical sensor. [ABSTRACT FROM AUTHOR]

In this work, a novel catalytic synthesis and functionalization method using apoferritin is used to fabricate RuO 2 nanoparticles (NPs) loaded WO 3 nanofibers (NFs) for potential diagnosis of diabetes. Catalytic ruthenium (Ru) NPs with very small average diameters of 1.8 ± 0.9 nm were synthesized using apoferritin which is a hollow protein cage, and were easily functionalized on WO 3 NFs by introducing electrospinning solution with W precursor and polyvinylpyrrolidone (PVP). As-spun Ru NPs-loaded W precursor/PVP composite NFs were calcined at 600 °C for 1 h in air atmosphere to achieve RuO 2 -functionalized WO 3 NFs. The small size and uniform distribution of catalytic RuO 2 NPs were well maintained due to hollow nature of apoferritin cages after calcination. The chemo-resistive sensors using RuO 2 -functionalized WO 3 NFs showed significantly enhanced acetone (CH 3 COCH 3 ) sensing response (R air /R gas = 78.61–5 ppm), which was 7.4 times higher than the response (R air /R gas = 10.61–5 ppm) of pristine WO 3 NFs at highly humid atmosphere (95% RH). In addition, the RuO 2 -functionalized WO 3 NFs showed outstanding selectivity toward acetone gas in comparison with other gases such as hydrogen sulfide (H 2 S), toluene (C 6 H 5 CH 3 ), ethanol (C 2 H 5 OH), pentane (C 5 H 12 ), ammonia (NH 3 ), hydrogen (H 2 ), and water vapor (H 2 O) at 5 ppm. These results represent potential feasibility for the detection of acetone in exhaled breath for diagnosis of diabetes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A nonlinear broadband piezoelectric energy harvester with a coupled beam array is proposed, which combines multi-resonance, coupling effect, and structural nonlinearity to broaden operational bandwidth and improve energy harvesting efficiency. • The coupling effect is numerically analyzed between two beams. • The energy harvesting performance of the harvester is compared with a non-coupled multi-resonance harvester constructed by individually separated beams, to show its superiority. • An energy harvesting demonstration on a sensor claims that the harvester can generate useful power for IoT devices. • Vehicle engine test verifies that the harvester can be applied in unstable conditions where varying frequencies exist. A conventional energy harvester usually has narrow operational bandwidth, which makes it difficult to harvest energy with varying frequencies in the actual field. Herein, a nonlinear piezoelectric energy harvester with a coupled beam array is designed to broaden bandwidth and improve energy harvesting performance. The proposed harvester consists of a base, two elastic supports, and four piezoelectric beams with different natural frequencies. Due to the coupling effect caused by the two elastic supports, the four piezoelectric beams have large output voltages not only at their own natural frequencies, but also at the natural frequencies of other beams. Meanwhile, the two elastic supports enable the four piezoelectric beams to become nonlinear beams, which also contributes to operational bandwidth broadening. Next, the equivalent mass-spring-damping model and governing equations of the harvester are obtained, based on the lumped-parameter method. A strong coupling is found to occur when the equivalent stiffness of the elastic support is small. Subsequently, a fabricated prototype and an experiment platform are utilized to measure the energy harvesting performance of the harvester. Under 1 g up-sweep excitation, the average output power of the harvester from 40 Hz to 80 Hz is 144.2 % higher and the bandwidth is 93.3 % wider than those of the non-coupled multi-resonance harvester, which houses four beams separately. Finally, actual applicability of the proposed energy harvester is evaluated by operating a Bluetooth location tracking Internet of Things (IoT) device without a battery. Besides, the fabricated prototype is applied to the vehicle engine where the frequencies of vibration sources change rapidly with time and velocity. The field test argues that the harvester can be used in unstable or varying conditions, where a typical vibration energy harvester may not work efficiently, due to its limited operational bandwidth. [ABSTRACT FROM AUTHOR]

In this work, catalytic Rh 2 O 3 -functionalized WO 3 nanofibers (NFs) were synthesized via an electrospinning route and used as a highly selective acetone-sensing layer for potential diagnosis of diabetes. Catalytic rhodium nanoparticles (Rh NPs) with average diameters of 5.0 ± 0.52 nm, which were synthesized by the polyol process, were dispersed in water with W precursor and poly(vinylpyrrolidone) (PVP) for electrospinning. As-spun Rh NP-loaded W precursor/PVP composite NFs were calcined at 600 °C for 1 h in air atmosphere to achieve Rh 2 O 3 -decorated WO 3 NFs. Microstructure evolution and chemical composition of Rh 2 O 3 -decorated WO 3 NFs as a function of Rh-loading amounts, i.e., 0.01 wt%, 0.05 wt%, 0.10 wt%, and 0.15 wt%, were examined using energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM). The mean size (30 nm) of the WO 3 crystallites in Rh 2 O 3 -decorated WO 3 NFs was much smaller than that (60 nm) of the WO 3 crystallites in pristine WO 3 NFs. The Rh 2 O 3 -decorated WO 3 NFs showed outstanding acetone (CH 3 COCH 3 ) sensing response ( R air / R gas = 41.2 to 5 ppm), which was 4.6 times higher than the response ( R air / R gas = 9.0 to 5 ppm) of pristine WO 3 NFs at highly humid atmosphere (95% RH). In addition, superior acetone cross-sensitivity of the Rh 2 O 3 -decorated WO 3 NFs was observed in other interfering gases such as pentane ( n -C 5 H 12 ), ammonia (NH 3 ), toluene (C 6 H 5 CH 3 ), carbon monoxide (CO), and ethanol (C 2 H 5 OH) at 5 ppm. These results are highly promising for the accurate and selective detection of acetone in exhaled breath for potential diagnosis of diabetes. [ABSTRACT FROM AUTHOR]

In this work, highly porous WO 3 nanotubes (NTs) were synthesized by facile layer-by-layer (LbL) self-assembly on polymeric nanofiber (NF) templates followed by calcination. Polymeric NFs using poly(methyl methacrylate) (PMMA) were prepared by electrospinning as sacrificial templates. Then, ionic polymers were coated on PMMA to modify the surface charge of PMMA NFs. Catalyst-loaded WO 3 NTs were synthesized by self-assembly of tungsten precursor and catalytic precursor on the surface of the polymeric PMMA NFs followed by calcination at 500 °C for 1 h. Gas sensing performances were evaluated in highly humid atmosphere (90% RH) using pristine WO 3 NTs, Pt-loaded WO 3 NTs (Pt-WO 3 NTs), and Pd-loaded WO 3 NTs (Pd-WO 3 NTs). Pristine WO 3 NTs exhibited a high NO response ( R gas / R air = 63.59 at 5 ppm) at 350 °C and cross-selectivity toward toluene ( R air / R gas = 1.05 at 5 ppm). On the other hand, Pt-WO 3 NTs and Pd-WO 3 NTs exhibited a high toluene response ( R air / R gas = 2.24 for the Pt-WO 3 NTs and R air / R gas = 2.35 for the Pd-WO 3 NTs at 5 ppm) at 400 °C and a negligible NO response ( R gas / R air = 1.25 for the Pt-WO 3 NTs and R gas / R air = 1.04 for the Pd-WO 3 NTs at 5 ppm) at 400 °C. These results demonstrated that LbL synthesis is a highly promising method for producing hollow semiconductor metal oxide NTs functionalized with various catalysts, which leads to potential application in exhaled breath analysis for asthma and lung cancer diagnosis. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple but powerful solution to overcome the chronic bottleneck of the nanocatalyst delivery on oxide support: the carbothermal shock driven nanocatalyst formation on carbon nanofibers (CNFs) with small sizes and fine distribution can be delivered to oxide structures of choice while retaining high uniformity. • Fabrication of catalyst delivered porous oxide structures: the asymmetric sputtering of oxide on CNFs can induce the formation of openly porous hemi-tubular structures with tunable porosity and thickness. A simple subsequent calcination results in the transfer of catalysts from the CNF template to the porous oxide structures. • Superior hydrogen sulfide sensing properties: Uniform distribution of Pt nanoparticles on SnO 2 hemitubes showed superior H 2 S sensing performances (Response Rair/Rgas > 1500 at 5 ppm H 2 S) compared to state-of-the-art H 2 S sensors. To achieve powerful gas sensors oxide semiconductor chemiresistors, the uniform functionalization of nanocatalysts on the desired metal oxides is considered as a key strategy. However, still, it is challenging to achieve the nanocatalysts decoration on desired oxides without deterioration of target materials. In this study, thermal-shock (rapid joule-heating method) was applied to uniformly decorate Pt nanoparticles (NPs) on the surface of carbon nanofibers (CNFs) to achieve the uniform distribution of Pt NPs on one-dimensional structures. And then, SnO 2 was physically deposited on the Pt NPs loaded CNFs and continuous heat-treatment was conducted to transfer the Pt NPs to desired SnO 2 porous hemitubes. Thanks to the well-distributed Pt NPs on porous SnO 2 hollow structures, the Pt laoded SnO 2 hemitubes showed an exceptional sensitivity (R air /R gas = 1500 at 5 ppm) in H 2 S. Also, it showed high selectivity for H 2 S and high stability even under continuous gas exposure, confirming its potential as an effective H 2 S sensor. [ABSTRACT FROM AUTHOR]