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Electrochemical and chemical phase transformations of α-Co(OH)2 into various other cobalt hydroxides were performed, and their structures were characterized to discern the correlation between electrocatalytic activity and crystal structure.

Enhancement of redox-reversibility in electroactive species has been studied because of fundamental interest and their importance for energy storage systems. Various electroactive molecules suffer from redox-irreversible behavior, and this is a critical reason for their exclusion as redox electrolytes in energy storage systems. In this article, we fully demonstrated that ascorbic acid (ASC), which is an abundant but redox-irreversible molecule, can become redox-reversible when it is confined in microporous carbon regimes. From a theoretical perspective, redox-reversibility in an electrochemical reaction coupled with an irreversible chemical process can be greatly enhanced due to kinetic acceleration toward the inverse direction of the chemical reaction by accumulation of products in the nanoconfined regime. However, the kinetic acceleration in a nanoconfined domain shows limitations for enhancing the redox-reversibility, which indicates that stabilization of the species undergoing an irreversible chemical process is another important factor for redox-reversibility enhancement. The origin of nanoporous confinement of ASC and its enhanced redox-reversibility was rationalized by molecular dynamics simulations. We found that ASC-clusters of a fully protonated ASC and its conjugated base formed inside carbon pores, which would be a main driving force for its confinement in microporous carbon networks. Lastly, we demonstrated a prototype energy storage device using redox-reversible ASC in microporous carbon as the half electrode, which shows the feasibility of ASC as a possible redox electrolyte in an aqueous energy storage system.

Lumbar intervertebral disc herniation (LDH) is a clinically symptomatic condition caused by compression of the spinal nerve root by protruded disc material. LDH can be treated with various endoscopic procedures. Recently, trans-sacral epiduroscopic laser decompression (SELD) using epiduroscopy and laser is one of the preferred options for minimally invasive treatment in lumbar disc diseases. Epiduroscopy has been employed because of the smaller diameter of the access portal and the flexible fiber when compared with transforaminal endoscopic lumbar discectomy. It allows treatment of a symptomatic herniated disc that has failed to respond to conservative treatment. SELD showed rapid improvement of back pain and radiculopathy with significant differences in the visual analog scale (VAS) and Oswestry Disability Index (ODI) scores between preoperative and postoperative data in the present study. The advantages of the SELD are direct decompression by laser and targeted mechanical adhesiolysis through direct visualization and very low complication rates. SELD is a safe and effective treatment for lower back and leg pain which arise from a herniated lumbar disc.

This paper proposes a new test method of detecting the presence of impulsive noise based on a complementary cumulative density function (CCDF). Impulsive noise severely degrades performance of communication systems and the conventional Kolmogorov&ndash, Smirnov (K&ndash, S) test may not perform well, because the test does not consider the characteristics of impulsive noise. In order to detect the presence of impulsive noise reliably, the CCDF of measurement samples is analyzed and compared with the CCDF of additive white Gaussian noise to find the difference between those CCDFs. Due to the nature of heavy-tails in impulsive noise, only the maximum difference may not be sufficient for the accurate detection of impulsive noise. Therefore, the proposed method applies the test hypothesis using the weighted sum of all the differences between those CCDFs. Simulation results justify that the proposed test is more robust and provides lower miss detection probability than the K&ndash, S test in the presence of impulsive noise.

Recently, convolutional neural networks (CNNs) achieved remarkable success in various fields, especially computer vision and image processing. However, it is not known what type of CNN architecture is the best fit for the detection or classification of communication signals. In this work, we compare the three of CNN architecture in a burst signal detection task. The three CNN architectures are compared to their detection performance and computational complexity. The 9-layer CNN is shown to achieve a similar performance of 12-layer CNN on overall environments. The performance of the 7-layer CNN model is worse than that of the other two types of CNN architectures, except in terms of the computational complexity at low SNR.

A BiVO

Correction for ‘Chemical and electrochemical synthesis of cobalt hydroxides: selective phase transformation and application to distinct electrocatalytic reactions’ by Joon Yong Park et al., J. Mater. Chem. A, 2022, https://doi.org/10.1039/d2ta02166h.

Azo compounds are self-reactive chemicals that violently produce flammable gases with heat release (i.e., an exothermic reaction). However, the explosion mechanism and ignition probability of azo compounds have not been clearly defined for storage or transportation. In this study, explosion scene analyses and various pyrolysis tests were performed to evaluate the thermal decomposition characteristics and explosion phenomena of azo compounds in a storage facility. The chemical debris collected from a fire scene was determined to be similar to the pyrolyzate of one of the tested azo compounds used by Py-GCMS. The minimum amounts of azo compounds, which could be ignited by self-decomposition heat, were calculated from the results of differential scanning calorimetrys and the heat transfer equation. The results were used to discuss a safety and response strategy for preventing the propagation of an explosion accident, namely a chemical backdraft.

In this study, iron carbide (Fe3C) particles were encapsulated in graphitic carbon shells by a facile carbonation process. These core-shell carbides, in which iron carbide is encapsulated in graphene-like layer (Fe3C@C) and nitrogen doped graphene-like layer (Fe3C@C–N) were investigated as oxygen evolution reaction (OER) catalysts to investigate the effect of the carbon shell on catalyst activity and stability. Due to the protective effect of the graphitic carbon shells, the performance of Fe3C@C and Fe3C@C–N were considerably better than the bare Fe3C nanoparticles. The OER activity of Fe3C@C–N is comparable with that of carbon-supported ruthenium oxide (RuO2/C), and this core-shell carbide has a remarkable stability and high turnover frequency under alkaline conditions. To elucidate the real active sites of these core-shell carbides, the role of the Fe3C core, Fe–Nx active sites, and effect of nitrogen doping in the shell were investigated in detail.

Ammonia borane (NH 3 BH 3 ), as a source material for energy generation and hydrogen storage, has attracted growing interest due to its high hydrogen content. We have investigated the synthesis of ammonia borane from diborane (B 2 H 6 ) and ammonia (NH 3 ) utilizing a low-temperature process. From our results, a maximum synthetic yield of 92.2% was obtained, for an ammonia borane complex of 0.35 M. The diammoniate diborane (DADB) was detected in about 5–10 mol% within the solid ammonia borane by solid-state 11 B-NMR analysis. The synthesized solid ammonia borane products were studied to characterize hydrogen release upon thermal dehydrogenation.

This paper proposes two non-uniform quantization schemes and also introduces an implementation system based on Software Defined Radio (SDR) consisting of GNU Radio and Universal Software defined Radio Peripheral (USRP) to sense a spectrum. In cognitive radio (CR) systems, detection and error probability are representative indicators of system performance. These performance indicators are influenced by various variables, among which the energy measurements quantization affected before reporting to the fusion center. In order to minimize performance loss due to the quantization errors, it is important to understand the impact of the number of quantization levels and the quantization intervals on the performance of the overall system. This paper reports a detection and error probability performance of a CR system applied non-uniform quantization schemes consisting of SDR platform.

Nanoparticles of Ni and Ni–Al2O3 were coated on a molten carbonate fuel cell (MCFC) anode by spray method to enlarge the electrochemical reaction sites at triple phase boundaries (TPBs). Both nano Ni coated anode and nano Ni–Al2O3 anode exhibited significant reduction of anode polarization, thanks to smaller charge transfer resistance. The maximum power density of nano Ni coated anode was 159 mW cm−2 at current density of 300 mA cm−2 operating at 600 °C. This is about 7% increase from the standard cell performance tested and compared in the study. Although low performance of nano coated Ni–Al2O3 cell is observed due to electrolyte consumption, the stability of cell performance during operation time is more favorable in MCFCs operation.

Nickel aluminum (Ni–Al) alloy anodes have become the preferred choice in anode material and have received widespread attention in molten carbonate fuel cell (MCFC) research due to their high durability and effectiveness in resisting creep of stack loadings. They are, however, susceptible to hydrogen sulfide (H2S) poisoning, which results in pore compression and rapid reduction of active sites for the electro-catalytic reaction. In this work, iron is introduced into a conventional Ni–Al anode to improve the creep resistance and tolerance to H2S. Anodes containing 30 wt.% Fe have a low creep strain of ca. 3%, but their creep resistance is much better than that of standard anodes. Single cells operated stably over 1000 h with a low voltage loss of ca. 5 mV. When exposed to H2S, the modified anode exhibited excellent recovery from the poisoning effect.

Ni-(3,5) wt.% Al-(3–10) wt.% Cr alloys suitable for use as an anode material for molten carbonate fuel cells (MCFCs) were prepared by a solid-gas-solid diffusion method. The creep resistances and sintering resistances of the prepared Ni–Al–Cr alloy samples evaluated in the creep test system were significantly improved with increasing Al and Cr concentration. The Ni-5 wt.% Al-10 wt.% Cr alloy showed the best creep resistance with a creep strain of 1.7% among as-prepared samples. To determine the electrochemical performance of the Ni–Al–Cr alloy anode, a single cell test was carried out. The cell performances of all the Ni–Al–Cr alloy anodes were above 0.8 V at 150 mA cm−2 for 1000 h of operation. It was also verified that the addition of Cr to Ni–Al enhances the ductility of the alloy and thus reduces micro-crack formation in the Ni–Al–Cr anode during cell operation. Therefore, it can be concluded that the Ni–Al–Cr alloy anode is a good candidate anode material for MCFCs.

Titanium dioxide (TiO2) nanotube arrays are grown in a mixed electrolyte by anodizing process. The anodic nanotubes for N-doping were calcinated at 773 K in a tube furnace with a mixture of NH3 and Ar gas. The photocatalytic activity of N-doped TiO2 nanotubes was carried out in a water-splitting reaction under UV and visible light irradiation. Various characterization techniques (Scanning electron microscopy, X-ray diffractometry, X-ray photo-electron spectroscopy, etc.) are used to study the surface morphology, phase of structure, and binding energy.

The durability of PEM fuel cells as a function of different humid conditions and MEA degradation were investigated by on/off cyclic operation. The maximum numbers of cycles determined by cycle at 10% of cell voltage loss were 1980, 1650, 1100, 520, and 320 cycles at relative humidity (RH) of 1000, 80, 50, 30, and 10%, respectively. The increases of ohmic resistance were observed at the high humid conditions of RH 100 and 80%. On the other hand, the charge transfer resistance increased at low humid conditions of RH 50, 30, and 10%. The losses of electrochemical surface area were obtained about 21% and 7% under RH 50 and 30% after the on/off cyclic operations, respectively. The thickness of electrode was reduced in the both anode and cathode layer, indicating that carbon corrosion occurred during on/off cycling. At cathode layer, the growth and migration platinum particles into polymer electrolyte were detected by XRD and TEM analyses.

The durability of PEMFCs is one of the most important issues for application in automotive vehicles with a repeated start-up and shut-down system. The understanding of degradation phenomena such as causes, mechanisms and influence of working condition is essential to improving the performance and lifetime of PEMFC. We conducted on/off cyclic operation in a single cell configuration with ultra purity nitrogen gas to investigate the physical degradation of membrane electrode assembly (MEA). After on/off cycle operation for 100,000 cycles under different humid condition, the characteristics of the MEAs were examined by in situ and ex situ analyses techniques. The physical degradation of MEA by on/off cycling led to a change in the membrane-electrode interfacial structure, which is mainly attributed to the loss of cell performance.

TiO2 nanotube arrays were grown on Ti foil in mixed electrolyte by the anodizing process. TiO2 nanotube arrays were immersed in the TiCl4 solution to improve the photocurrent by enhanced charge transfer between TiO2 and dye molecules on the activity surface. Internal resistance of dye-sensitized solar cells (DSSC) was measured by impedance spectroscopy measurements. Backside illuminated DSSC with TiCl4-treated TiO2 nanotubes exhibited a conversion efficiency of 1.45% and showed improved electron transfer.

The ternary system SiO2-P2O5-ZrO2 electrolyte and phosphotungstic acid (PWA) doped SiO2-P2O5-ZrO2 electrolyte were prepared for intermediate temperature fuel cell by using sol-gel technique. These silica-based proton conductors were confirmed to be non-crystalline structure without phase separation and good thermal stability by XRD and TG/DTA analysis. The doped PWA was found to be stabilized within the silica matrix and to enhance the proton conductivity. The proton conductivities of SiO2-P2O5-ZrO2 and SiO2-P2O5-ZrO2-PWA electrolytes showed 3.3×10−5 and 1.8×10−3 S/cm at 90 °C, respectively, and the cell performance of SiO2-P2O5-ZrO2-PWA electrolyte was obtained as 0.02–0.25 mA/cm2 at 300 °C under humid condition.

The multicomponent proton conducting ceramics SiO 2 ―TiO 2 ―ZrO 2 ―P 2 O 5 (STZP) and SiO 2 ―TiO 2 ―ZrO 2 ―P 2 O 5 ―Bi 2 O 3 with three different compositions (STZPBi3, STZPBi10, and STZPBi15) were synthesized via a wet chemical route. These prepared materials showed good thermal stability up to around 900°C by TG/DTA analyses. Introduction of optimum quantity of bismuth as a sintering aid into the samples contributed to enhance the densification of microstructure, which is essential for the utilization of proton conducting ceramics in fuel cells operated at elevated temperature. The proton conductivity of STZP was 3.6×10 ―5 Slcm at 80°C and that of STZPBi10 was 4.6×10 ―3 Slcm at 180°C. The fuel cell performances using STZP and STZPBi10 were implemented at 80°C and up to 230°C, respectively. The maximum power density was 0.03 mW/cm 2 at 80°C for the STZP sample and 2.5 mW/cm 2 at 150°C for the STZPBi10 sample under wet hydrogen and dry oxygen. The reduction of CO poisoning on platinum catalyst was demonstrated in fuel cell operating at temperatures of 180 ° C, 200 ° C, and I 230°C.

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