Enhanced Gas-Sensing Performance of GO/TiO2 Composite by Photocatalysis.

Few studies have investigated the gas-sensing properties of graphene oxide/titanium dioxide (GO/TiO2) composite combined with photocatalytic effect. Room temperature gas-sensing properties of the GO/TiO2 composite were investigated towards various reducing gases. The composite sensor showed an enhanced gas response and a faster recovery time than a pure GO sensor due to the synergistic effect of the hybridization, such as creation of a hetero-junction at the interface and modulation of charge carrier density. However, the issue of long-term stability at room temperature still remains unsolved even after construction of a composite structure. To address this issue, the surface and hetero-junction of the GO/TiO2 composite were engineered via a UV process. A photocatalytic effect of TiO2 induced the reduction of the GO phase in the composite solution. The comparison of gas-sensing properties before and after the UV process clearly showed the transition from n-type to p-type gas-sensing behavior toward reducing gases. This transition revealed that the dominant sensing material is GO, and TiO2 enhanced the gas reaction by providing more reactive sites. With a UV-treated composite sensor, the function of identifying target gas was maintained over a one-month period, showing strong resistance to humidity.

Water soluble sodium sulfate nanorods as a versatile template for the designing of copper sulfide nanotubes.

The present study reports the use of water soluble sodium sulfate (Na2SO4) nanorods as a versatile template for generation of tubular copper sulfide (CuS) nanostructures. The Na2SO4 nanorods were synthesized from ammonium sulfate (NH4)2SO4 and sodium hydroxide (NaOH), under refluxing condition. The shape and morphology control of the Na2SO4 nanorods were studied with respect to nature of surfactant used and reactant mole ratio. While, PVP mole ratio was important to obtain homogeneous nanorods. Uniform and stable nanotubes of CuS were than obtained by the dissolution of the nanorods in water. The use of simple chemicals for synthesis of such nanotube templates opens the prospect for wide scale downstream applications.

Corrigendum: Enhanced electrochemical properties of catalyst by phosphorous addition for direct urea fuel cell.

[This corrects the article DOI: 10.3389/fchem.2020.00777.].

Hierarchical PtCuMnP Nanoalloy for Efficient Hydrogen Evolution and Methanol Oxidation.

The higher amount of Pt usage and its poisoning in methanol oxidation reaction in acidic media is a major setback for methanol fuel cells. Herein, a promising dual application high-performance electrocatalyst has been developed for hydrogen evolution and methanol oxidation. A low Pt-content nanoalloy co-doped with Cu, Mn, and P is synthesized using a modified solvothermal process. Initially, ultrasmall ≈2.9 nm PtCuMnP nanoalloy is prepared on N-doped graphene-oxide support and subsequently, it is characterized using several analytical techniques and examined through electrochemical tests. Electrochemical results show that PtCuMnP/N-rGO has a low overpotential of 6.5 mV at 10 mA cm-2 in 0.3 m H2 SO4 and high mass activity for the hydrogen evolution reaction. For the methanol oxidation reaction, the PtCuMnP/N-rGO electrocatalyst exhibits robust performance. The mass activity of PtCuMnP/N-rGO is 6.790 mA mg-1 Pt , which is 7.43 times higher than that of commercial Pt/C (20% Pt). Moreover, in the chronoamperometry test, PtCuMnP/N-rGO shows exceptionally good stability and retains 72% of the initial current density even after 20,000 cycles. Furthermore, the PtCuMnP/N-rGO electrocatalyst exhibits outstanding performance for hydrogen evolution and methanol oxidation along with excellent anti-poisoning ability. Hence, the developed bifunctional electrocatalyst can be used efficiently for hydrogen evolution and methanol oxidation.

Optimization of LiNiCoMnO2 Cathode Material Synthesis Using Polyvinyl Alcohol Solution Method for Improved Lithium-Ion Batteries.

The growing need for lithium-ion batteries, fueled by the widespread use of electric vehicles (EVs) and portable electronic devices, requires high energy density and safety. The cathode material Li1-x(NiyCozMn1-y-z)O2 (NCM) shows promise, but attaining high efficiency necessitates optimization of both composition and manufacturing methods. Polycrystalline LiNiCoMnO2 powders were synthesized and assessed in this investigation using a polyvinyl alcohol (PVA) solution method. The study examined different synthesis conditions, such as the PVA to metal ions ratio and the molecular weight of PVA, to assess their influence on powder characteristics. Electrochemical analysis indicated that cathode materials synthesized with a relatively high quantity of PVA with a molecular weight of 98,000 exhibited the highest discharge capacity of 170.34 mAh/g and a high lithium-ion diffusion coefficient of 1.19 × 10-9 cm2/s. Moreover, decreasing the PVA content, irrespective of its molecular weight, led to the production of powders with reduced surface areas and increased pore sizes. The adjustments of PVA during synthesis resulted in pre-sintering observed during the synthesis process, which had an impact on the long-term stability of batteries. The electrodes produced from the synthesized powders had a positive impact on the insertion and extraction of Li+ ions, thereby improving the electrochemical performance of the batteries. This study reveals that cathode materials synthesized with a high quantity of PVA with a molecular weight of 98,000 exhibited the highest discharge capacity of 170.34 mAh/g and a high lithium-ion diffusion coefficient of 1.19 × 10-9 cm2/s. The findings underscore the significance of optimizing methods for synthesizing PVA-based materials to enhance the electrochemical properties of NCM cathode materials, contributing to the advancement of lithium-ion battery technology. The findings underscore the significance of optimizing methods for synthesizing PVA-based materials and their influence on the electrochemical properties of NCM cathode materials. This contributes to the continuous progress in lithium-ion battery technology.

Development of A 14.8-MEV Mono-Energetic Neutron Field in Korea Research Institute of Standards and Science.

A standard irradiation field for 14.8-MeV neutrons is under development for mono-energetic neutron standards research in the Korea Research Institute of Standards and Science, Republic of Korea. We developed a target chamber with the associated alpha particle (AAP) system for 14.8-MeV mono-energetic neutrons by a T(d,n)4He reaction. We designed the target chamber and the AAP detector system using a two-body kinematic calculation. We conducted simulations of the T(d,n)4He reaction on a tritiated target to determine a specification of the target and the AAP detector. This paper will discuss the simulation and calculation results for the associated particle system design.

Frontal peripheral osteomas: a retrospective study.

BACKGROUND: Osteomas are benign, slow-growing bone tumors that can be classified as central, peripheral, or extraskeletal. Central osteomas arise from the endosteum, peripheral osteomas from the periosteum, and extraskeletal osteomas within the muscle. Frontal peripheral osteomas are mainly encountered in plastic surgery. In this study, we retrospectively analyzed the clinical data of patients with frontal peripheral osteomas. METHODS: We retrospectively reviewed the medical records of patients who visited our hospital with frontal peripheral osteomas between January 2014 and June 2022. We analyzed the following variables: age, sex, tumor type (sessile or pedunculated), single or multiple, size, history of head trauma, operation, and recurrence. RESULTS: A total of 39 patients and 41 osteomas were analyzed, of which 29 osteomas (71%) were sessile and 12 osteomas (29%) were pedunculated. The size of the osteomas ranged from 4 to 30 mm, with an average size of 10 mm. The age of patients ranged from 4 to 78 years with a mean age of 52 years. There were seven men (18%) and 32 women (82%), and the man-to-woman ratio was 1:4.6. Two patients (5%) had multiple masses, with two osteomas in each, while only two patients (5%) had a history of head trauma. Twenty-nine patients (74%) underwent ostectomy by a direct approach, and none of the patients experienced recurrence. CONCLUSION: The epidemiologic data of our study will help plastic surgeons encounter frontal peripheral osteomas in the field to provide proper management for their patients.

Enhanced Thermal Stability and Conductivity of FeF3 Using Ni-Coated Carbon Composites: Application as High-Temperature Cathodes in Thermal Batteries.

Cathode active materials and conductive additives for thermal batteries operating at high temperatures have attracted research interest, with a particular focus on compounds offering high thermal stability. Recently, FeF3 has been proposed as a candidate for high-voltage cathode materials; however, its commercialization is hindered by its low conductivity. In this study, conductive additives, such as Ni-coated carbon composites (multi-walled carbon nanotubes (MWCNTs) and carbon black (CB)), were utilized to enhance the thermal stability and conductivity of FeF3. The incorporation of metal-carbon conductive additives in the FeF3 composite increased the thermal stability by more than 10 wt.% and ensured high capacity upon conductivity enhancement. The FeF3@Ni/MWCB 15 wt.% composite containing 30 wt.% Ni exhibited a discharge capacity of ∼86% of the theoretical capacity of 712 mAh/g. The use of Ni-coated carbon-based conductive additives will allow the application of FeF3 as an effective high-temperature cathode material for thermal batteries.

FeF3/(Acetylene Black and Multi-Walled Carbon Nanotube) Composite for Cathode Active Material of Thermal Battery through Formation of Conductive Network Channels.

Considerable research is being conducted on the use of FeF3 as a cathode replacement for FeS2 in thermal batteries. However, FeF3 alone is inefficient as a cathode active material because of its low electrical conductivity due to its wide bandgap (5.96 eV). Herein, acetylene black and multi-walled carbon nanotubes (MWCNTs) were combined with FeF3, and the ratio was optimized. When acetylene black and MWCNTs were added separately to FeF3, the electrical conductivity increased, but the mechanical strength decreased. When acetylene black and MWCNTs were both added to FeF3, the FeF3/M1AB4 sample (with 1 wt.% MWCNTs and 4% AB) afforded a discharge capacity of approximately 74% of the theoretical capacity (712 mAh/g) of FeF3. Considering the electrical conductivity and mechanical strength, this composition was confirmed to be the most suitable.

Anion Exchange Membranes for Fuel Cell Application: A Review.

The fuel cell industry is the most promising industry in terms of the advancement of clean and safe technologies for sustainable energy generation. The polymer electrolyte membrane fuel cell is divided into two parts: anion exchange membrane fuel cells (AEMFCs) and proton exchange membrane fuel cells (PEMFCs). In the case of PEMFCs, high-power density was secured and research and development for commercialization have made significant progress. However, there are technical limitations and high-cost issues for the use of precious metal catalysts including Pt, the durability of catalysts, bipolar plates, and membranes, and the use of hydrogen to ensure system stability. On the contrary, AEMFCs have been used as low-platinum or non-platinum catalysts and have a low activation energy of oxygen reduction reaction, so many studies have been conducted to find alternatives to overcome the problems of PEMFCs in the last decade. At the core of ensuring the power density of AEMFCs is the anion exchange membrane (AEM) which is less durable and less conductive than the cation exchange membrane. AEMFCs are a promising technology that can solve the high-cost problem of PEMFCs that have reached technological saturation and overcome technical limitations. This review focuses on the various aspects of AEMs for AEMFCs application.

Electrospun Poly(Styrene-Co-Vinylbenzyl Chloride-Co-Acrylonitrile) Nanofiber Mat as an Anion Exchange Membrane for Fuel Cell Applications.

A nanofiber mat of styrene-co-vinylbenzyl chloride-co-acrylonitrile copolymer as an anion exchange membrane (AEM) was synthesized via the electrospinning of organic reaction mixtures. The synthesized membranes were characterized using FT-IR spectroscopy for structural analysis. The AEM demonstrated a high ionic conductivity mainly due to the phase segregation in the membrane structure, as analyzed by transmission electron microscopy (TEM). The membrane properties such as water uptake, swelling ratio, and ion exchange capacity, as well as ionic conductivity, varied with the chemical composition. With the molar ratio of styrene, vinylbenzyl chloride, and acrylonitrile at 3:5:2, the highest ionic conductivity of 0.214 S cm-1 at 80 °C was observed. Additionally, the AEM retained 94% of original conductivity after 72 h of soaking in 1 M KOH solution.

Shear behavior of single cast-in anchor simulating characteristics of bridge bearing anchor.

A bridge bearing anchor transmits various loads of a superstructure to a substructure. Most anchors are generally designed without consideration of characteristics such as concrete pedestal, grout bedding, and anchor socket. This study investigated the shear behavior of anchors in accordance with the edge distance, embedment depth, compressive strength of concrete, and height of the concrete pedestal in order to simulate the practical characteristics of the bridge bearing anchors. The actual shear capacity of the anchor differs from the shear strengths calculated by the ACI 318 and EN 1992-4; especially, the importance of the embedment depth is underestimated in these codes. An increase in the height of the concrete pedestal has a negative effect on the shear capacity because of the stress concentration. The grout is fractured prior to the occurrence of local damages in concrete, resulting in a secondary moment. As a result, the effect of the level arm is observed. An equation, which can predict the relative cracking degree of concrete, is proposed by analyzing the displacement of grout and concrete. High strain occurs in the stirrups close to the anchor, and the behavior of the strain is more influenced by the embedment depth than the edge distance. The comparison of obtained and analytically evaluated failure loads by calculations according to EN 1992-4, Schmid model and Sharma model was conducted to consider the effect of supplementary reinforcement. Finally, the design equation of concrete breakout strength is modified to predict the more precise shear resistance of a bridge bearing anchor.

Incorrect depth sense due to focused object distance.

In stereoscopy, stereoscopic depth distortion is a serious problem in terms of determining the correct depth sense. There have been few studies pertaining to the problem in terms of the focused object distance (FOD). In this investigation, we discuss the FOD as one of the factors inducing an incorrect depth sense in using common stereo camera systems and propose a method for compensating the incorrect depth sense, which is strongly related to the process of demagnifying the size of displayed stereo image on the screen. The incorrect depth sense increases when the FOD becomes shortened. Our method illustrates that the depth sense difference between a correct depth sense and an induced depth error is compensated completely. We verified the validation of our concerns by both a theoretical simulation and a practical experiment.

Effect of Co3O4 Nanoparticles on Improving Catalytic Behavior of Pd/Co3O4@MWCNT Composites for Cathodes in Direct Urea Fuel Cells.

Direct urea fuel cells (DUFCs) have recently drawn increased attention as sustainable power generation devices because of their considerable advantages. Nonetheless, the kinetics of the oxidation-reduction reaction, particularly the electrochemical oxidation and oxygen reduction reaction (ORR), in direct urea fuel cells are slow and hence considered to be inefficient. To overcome these disadvantages in DUFCs, Pd nanoparticles loaded onto Co3O4 supported by multi-walled carbon nanotubes (Pd/Co3O4@MWCNT) were employed as a promising cathode catalyst for enhancing the electrocatalytic activity and oxygen reduction reaction at the cathode in DUFCs. Co3O4@MWCNT and Pd/Co3O4@MWCNT were synthesized via a facile two-step hydrothermal process. A Pd/MWCNT catalyst was also prepared and evaluated to study the effect of Co3O4 on the performance of the Pd/Co3O4@MWCNT catalyst. A current density of 13.963 mA cm-2 and a maximum power density of 2.792 mW cm-2 at 20 °C were obtained. Pd/Co3O4@MWCNT is a prospectively effective cathode catalyst for DUFCs. The dilution of Pd with non-precious metal oxides in adequate amounts is economically conducive to highly practical catalysts with promising electrocatalytic activity in fuel cell applications.

Effects of COVID-2019 on plastic surgery emergencies in Korea.

BACKGROUND: To fight the coronavirus disease 2019 (COVID-19) pandemic, many countries have implemented social distancing and lockdowns. We investigated the changes in the trauma patterns of emergency plastic surgeries in the midst of a pandemic. METHODS: A retrospective review of the medical records of all patients treated for emergency plastic surgeries was performed at our hospital in Seoul. We conducted the analysis between March 1 and June 30, 2020, and compared the data obtained with that of the same period in 2019. We also investigated changes in trauma patterns according to the social distancing level from July 2020 to February 2021. RESULTS: There was a total of 800 emergency plastic surgery patients from March to June 2020, which was less than the 981 in the corresponding period in 2019. The proportion of patients aged 7-17 years and ≥ 80 in 2020 showed a significant decrease. In 2020, patients presenting with facial trauma decreased and hand trauma, markedly laceration, increased significantly. In 2020, more injuries happened at home, whereas significantly fewer injuries happened on the streets. In 2020, slipping and sports injury decreased, whereas penetrating injury increased significantly. In the changes observed according to the social distancing level, there were significant differences in age classification, facial open wound, and the mechanism of injury. CONCLUSION: Social distancing has caused a change in emergency plastic surgeries. To ensure safe and appropriate treatment, strict epidemiologic workup and protective equipment are required.

Shielding Effectiveness and Impact Resistance of Concrete Walls Strengthened by High-Strength High-Ductility Concrete.

Following the fourth Industrial Revolution, electronic and data-based technology is becoming increasingly developed. However, current research on enhancing electromagnetic interference (EMI) shielding and the physical protection performance of structures incorporating these technologies is insufficient. Therefore, in this study aiming for the improvement of EMI shielding and structural performance of structures, twelve concrete walls were fabricated and tested to determine their shielding effectiveness and drop-weight impact resistance. Concrete walls strengthened by three thickness types of high-strength, high-ductility concrete (HSDC) have been considered. The test results showed that the shielding effectiveness with strengthening thickness increased by approximately 35.6-46.2%. Specimens strengthened by more than 40% and 10% of the strengthening area ratio of single- and double-layer, respectively, exhibited more than 20 dB of shielding effectiveness. Moreover, the relationship between the damaged area ratio and shielding effectiveness was evaluated by means of the drop-weight impact test. The structural performance and EMI shielding effectiveness improved as the HSDC thickness increased.

Mechanical and Electrical Characteristics of Lightweight Aggregate Concrete Reinforced with Steel Fibers.

There is increased interest in applying electromagnetic (EM) shielding to prevent EM interference, which destroys electronic circuits. The EM shielding's performance is closely related to the electrical conductivity and can be improved by incorporating conductive materials. The weight of a structure can be reduced by incorporating lightweight aggregates and replacing the steel rebars with CFRP rebars. In this study, the effects of lightweight coarse aggregate and CFRP rebars on the mechanical and electrical characteristics of concrete were investigated, considering the steel fibers' incorporation. The lightweight coarse aggregates decreased the density and strength of concrete and increased the electrical conductivity of the concrete, owing to its metallic contents. The steel fibers further increased the electrical conductivity of the lightweight aggregate concrete. These components improved the EM shielding performance, and the steel fibers showed the best performance by increasing shielding effectiveness by at least 23 dB. The CFRP rebars behaved similarly to steel rebars because of their carbon fiber content. When no steel fiber was mixed, the shielding effectiveness increased by approximately 2.8 times with reduced spacing of CFRP rebars. This study demonstrates that lightweight aggregate concrete reinforced with steel fibers exhibits superior mechanical and electrical characteristics for concrete and construction industries.

Evaluation on the Microstructure and Durability of High-Strength Concrete Containing Electric Arc Furnace Oxidizing Slag.

The application of electric arc furnace oxidizing slag (EAS) in high strength concrete (HSC) as the cementitious material is investigated in this study. The microstructure and mechanical properties of HSC with four different replacement ratios of EAS were evaluated and HSC with two replacement ratios of ground granulated blast furnace slag (GBS) was used for performance comparison. The results show that the HSC with EAS replacement ratios smaller than 15% undergo similar hydration processes and result in a similar final product when compared with those of NC-NN. Increases in EAS replacement ratio cause a reduction in Ca(OH)2 content; this, in turn, leads to an increase in porosity and a reduction in compressive strength. In terms of shrinkage behavior under free conditions, mixtures with increasing replacement ratios of cementitious materials saw increasing shrinkage, with the HSC containing EAS being similar to the other specimens. The mixtures containing EAS saw a quite gradual decrease in their freezing and thawing resistance properties as the number of freeze-thaw cycles they underwent increased. However, the efficacy of HSC with less than 15% of EAS is similar to GBS; hence, EAS could replace cement in concrete for certain applications, which would lead to more environmental benefits.

Building-Information-Modeling Based Approach to Simulate Strategic Location of Shelter in Place and Its Strengthening Method.

It is important to consider establishing a shelter in place (SIP) using existing facilities to prepare for unpredictable and no-notice disasters. In this study, we evaluate the building-information-modeling (BIM)-based approach to simulate the strategic location of SIP and its strengthening method. BIM software was used to model a light rail station and analyze the elements of the facility that can affect the evacuation time to reach the SIP. The purpose of this study was to understand the effects of structural standards on the design of SIPs using a direct simulation. The differences between domestic and overseas standards were analyzed. An analysis was carried out to evaluate whether national specifications are satisfactory. As the proposed evacuation method is based on a rational human behavior analysis through a direct simulation, it was going to be a safer and faster route of evacuation in the case of physical terror attack situations for existing infrastructure, Furthermore, the SIP design is considered where reinforcement of the SIP structure is necessary. Three types of reinforcing were considered. Here, the use of high-strength, high-ductility concrete proved to be an effective method to improve the impact resistance of reinforced concrete walls and recommended for strengthening reinforced concrete members.