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•Multiaxial fatigue life research of the of tungsten-filled polychloroprene rubber.•Experiment utilizing notched specimens and limiting dome test experiments.•Semi-empirical fatigue ...model development considering anisotropy and triaxiality.•Additional fatigue life estimation considering machine learning-based models.•Reliable estimation of the fatigue life for both developed approaches.
In this paper, multiaxial fatigue experiments on a hyperelastic rubber-like material made of polychloroprene rubber (CR) reinforced with tungsten nano-particles have been carried out on notched specimens and hourglass specimens, utilized for limiting dome height fatigue tests. Based on the uniaxial (Choi et al., 2020) and multiaxial fatigue experiments, a semi-empirical ε-N fatigue model is proposed, allows accounting for both material anisotropy and complex stress states, showing an average error of 20.7%. Furthermore, six machine learning models have been employed for the fatigue life prediction and shown that the Deep Neural Network is the most accurate, with an average error equal to 14.3%.
Anodized films of aluminum alloys are composed of an inner thin barrier layer and an outer thick porous layer. A sealing process as a post treatment of anodizing, the porous layer achieves improved ...mechanical and chemical performance as well as decorative color. Nevertheless, dramatically increased hardness could not be achieved using traditional sealing processes. In this study, the sealing of anodized aluminum alloy was carried out by repetition of dipping in a hexavalent chromium oxide solution and heat treatment. The changes in the anodized layer before and after the sealing were analyzed by XRD and SEM. Electrochemical corrosion and wear rate test were also carried out. The hardness, wear resistance and corrosion resistance were compared with traditional sealing methods, such as boiling water and cold nickel fluoride. By heat treatment after dipping in a hexavalent chromium oxide solution, Cr2O3 was formed and filled the pores in the porous layer of the anodized film. Therefore, the hardness of the anodized film was increased with an improvement in wear resistance. In addition, improvement in corrosion resistance was achieved by Cr2O3 sealing.
► Sealing of anodized Al alloy by dipping in a CrO3 solution and heat treatment. ► Cr2O3 was formed during heat treatment. ► Cr2O3 filled the pores in the porous layer of the anodized film. ► The hardness and wear resistance of the anodized film were improved. ► Improvement in corrosion resistance was achieved.
•We fabricate the CuO/resin composite coating layer on aluminum alloy heat sink.•CuO/resin coating considerably improved the surface emissivity.•The LED junction temperature was reduced by CuO/resin ...coated heat sink.•The thermal resistance of heat sink was decreased by CuO/resin composite coating at 200μm thickness.
A composite coating composed of cupric oxide (CuO) and silicon-based resin was applied to an aluminum-alloy heat sink for a light emitting diode (LED) module. The purpose of the composite coating is to improve the heat dissipation performance of heat sink by enhancing thermal radiation emission. The heat dissipation performance was investigated in terms of LED junction temperature and thermal resistance using a thermal transient method. The CuO and silicon-based resin composite coating showed higher emissivity, and the lower junction temperature and thermal resistance of the heat sink was achieved. In addition, a continuous operation test of the LED chip with the heat sink revealed that the surface treated with the CuO composite coating stably dissipated heat without degradation. In conclusion, the composite coating proposed here showed a significant improvement of the heat dissipation performance of the aluminum-alloy heat sink due to the enhanced thermal radiation property.
Fluorescent materials are being used for the optical/fluorescence imaging of living cells and animal models. As such, the development of heavy‐metal‐free, water‐dispersible, and biocompatible imaging ...probes is still important. Carbon nitride (C3N4) is used as a bioimaging probe due to its suitable optical properties, thus enhancing its biocompatibility and dispersibility in aqueous media is required. In this study, we incorporated short‐chain polyethylene glycol (PEG) groups onto a carbon nitride network by the simple N‐alkylation of hexaethylene glycolic mesylate with nucleophilic nitrogen atoms on oxidized carbon nitride (OCN). The PEGylated OCN (PEG‐OCN) was well dispersed in water as nanodots with a lateral dimension of approximately 30 nm and a thickness of 0.5–1.2 nm and showed strong photoluminescence in the visible region. Cell‐viability testing confirmed that these “heavy‐metal‐free” organic nanodots were highly biocompatible and noncytotoxic. In particular, the developed nanodots could provide clear confocal images of RAW 264.7 cells without weakening cell activity and displaying any aggregation in a range of concentrations (25–100 μg mL−1) with bright‐green emission in the cytoplasm.
Glowing brightly: Ultrathin polyethylene glycosylated (PEGylated) oxidized carbon nitride (PEG‐OCN) nanodots have been designed and prepared that can act as a physiologically friendly “heavy‐metal free” bioimaging probe. In particular, the developed nanodots provide clear confocal images of RAW 264.7 cells with bright‐green emission in the cytoplasm (see picture; OMs=mesylate).
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•Plasma electrolytic oxidation and hydrothermal treatment are applied to Mg alloy.•Oil-impregnation and hydrophobizing enhances de-wetting of porous oxide layer.•Oil-impregnated ...hydrophobized nanoporous surface has superior corrosion resistance.•The surface shows durable corrosion resistance and de-wetting property.
Magnesium alloys have been widely employed for structural parts of aircrafts and automobiles to reduce their weight. However, magnesium alloys are easily corroded, thus practical applications always require protective coatings to guarantee satisfactory lifetime. In this study, we applied oil-impregnation and hydrophobizing to traditional plasma electrolytic oxidation (PEO) of magnesium alloy. Nanoporous hydroxide surface structure is fabricated by hydrothermal treatment of PEO-treated Mg alloy, then the self-assembled monolayer of perfluorodecyltrichlorosilane (FDTS) is coated for the hydrophobizing. The immiscible oil impregnation into the PEO-treated oxide layer with hydrothermal treatment and hydrophobizing significantly enhances the corrosion resistance as well as the mobility of water droplet on the surface. In addition, since the oil layer on the nanoporous surface inhibit the direct contact and penetration of corrosive liquid to the oxide layer, the oil-impregnated surface shows less degradation in corrosive liquid with long-term immersion than hydrophobic and superhydrophobic surface without oil-impregnation. These results indicates that oil-impregnated surface of Mg alloy has durable and robust anti-corrosion property.
Cigarette smoking is one of the leading causes of preventable and premature death worldwide. Even worse, many people are generally exposed to passive smoking, which leads to several respiratory ...diseases and related mortalities. Considering, more than 7000 compounds are included in cigarettes, their combustion results intoxicants that have deleterious effects on health. However, there is a lack of research analyzing the effects of smoking and passive smoking on all-cause and disease-specific mortality through its chemical compounds including heavy metals. Thus, this study aimed to evaluate the effect of smoking and passive smoking on all-cause and disease-specific mortality mediated by cadmium, one of the representative smoking-related heavy metals using data from the National Health and Nutrition Examination Survey (NHANES) 1999-2018 in the United States. We found that current smoking and passive smoking was related to increased risk of all-cause, CVD-related, and cancer-related mortality. Notably, passive smoking showed a synergistic effect with smoking status on the risk of mortality. In particular, current smokers with passive smoking had the highest risk of all-cause and disease-specific deaths. In addition, the accumulation of cadmium in the blood due to smoking and passive smoking mediates the increased risk of all-cause mortality. Further studies are needed to monitor and treat cadmium toxicity to improve smoking-related mortality rates.
Rational design and synthesis of advanced electrode materials are considered essential for realizing high-performance lithium-ion batteries for the fast-growing electric vehicle and energy storage ...applications. Herein, a novel and robust core-shell structured ZnO-based composite (denoted as ZnO@C) is prepared via the controlled growth of zeolitic imidazolate frameworks (ZIF–8) on the surface of ZnO nanoparticles followed by thermal treatment under nitrogen atmosphere, and is utilized as a lithium-ion battery anode. The microstructural characterization of the ZnO@C composite reveals that ZnO particles are well-embedded within a highly conductive nitrogen-doped carbon nanolayer. The obtained ZnO@C composite exhibits a high specific capacity of 798 mA h g−1 with an initial charge/discharge efficiency of 81%, good long-term cyclability of over 300 cycles at a high current density of 1 A g−1, and enhanced rate capability up to 2 A g−1 with a LiF-rich solid electrolyte interphase (SEI) formed in the presence of the fluoroethylene carbonate additive. These results suggest that the combination of the multifunctional ZIF–8-derived carbon coating and the use of electrolyte additive as a SEI modifier significantly improves the lithium storage performance of high-capacity metal oxide anodes.
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•ZnO@C composite was synthesized via growth and thermal decomposition of ZIF–8.•ZIF–8-derived carbon coating leads to volume-change mitigation and high conductivity.•LiF-rich SEI film formed by FEC provides enhanced interfacial/structural stability.•This composite demonstrates better lithium storage performance than pure ZnO.
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•The effects of NaCl on thermodynamic and kinetic CO2 selectivity were investigated.•The presence of NaCl enhanced thermodynamic CO2 selectivity in CO2 + N2 hydrate.•The conversion ...into CO2 + N2 hydrate was lower in the NaCl solution system.•The kinetic CO2 selectivity in the hydrate phase was more pronounced in the NaCl solution system.
The importance of carbon capture and storage (CCS) has recently been emphasized owing to the ever-increasing global warming. Direct CO2 sequestration in marine sediments is an attractive option for CO2 storage, and some amount of injected CO2 can be stored in the form of solid gas hydrates. In this study, the effects of NaCl on the hydrate phase equilibria, thermodynamic and kinetic CO2 selectivity, and time-dependent growth behaviors of CO2 + N2 hydrates were experimentally investigated to elucidate their implications for hydrate-based CO2 sequestration. The presence of NaCl shifted the equilibrium conditions of CO2 + N2 hydrates to the higher-pressure or lower-temperature region, whereas it increased thermodynamic CO2 selectivity at a specified temperature and pressure, which was also confirmed by the pressure-composition diagram. As revealed by powder X-ray diffraction analysis, the conversion into CO2 + N2 hydrate was lower in the saline water system because of the lower initial driving force and gradual salt enrichment in the residual solution during hydrate growth. In situ Raman spectroscopic measurements demonstrated that CO2 was kinetically selective at the early stage of CO2 + N2 hydrate formation and that kinetic CO2 selectivity was more noticeable in the saline water system. The overall results provide an in-depth understanding of the role of salts in CO2 + N2 hydrate formation and thus offer valuable insights into hydrate-based CO2 storage and geological CO2 sequestration.
•Present an automated framework for assessing dynamic characteristics of building structures with a conjunction of marker-free vision approach.•Formulate an algorithm for deriving lateral stiffness ...from displacement data by reconstructing the equation of motion.•Employ image convex hull optimization method to realize marker-free vision-based displacement sensor (MVDS).•Validate the propose framework in numerical and experimental ways.•Show distinct aspects of the proposed framework monitoring dynamic characteristics exceeding the Nyquist frequency of sensors.
Vision-based displacement sensors (VDSs) are drawing attention as next-generation methods for monitoring buildings due to easy installation, however, there is a further need to develop integrated techniques both to obtain displacement at desired positions and to assess dynamic characteristics with high-precision. This study aimed to develop an automated framework to assess the dynamic characteristics of buildings through the derivation of lateral stiffness using a marker-free vision-based displacement sensor (MVDS). The MVDS utilizes image convex hull optimization to measure displacement at user-defined positions without ancillary markers. Then, the dynamic characteristics were estimated from eigenvalue analysis by reconstructing the equation of motion based on lateral stiffness derived through linear regression in load-displacement curves using the measured displacement data. From numerical simulation and shake table test, the results showed that the proposed framework enables monitoring of the dynamic characteristics where frequency domain exceeded the Nyquist frequency of the sensor compared to FFT-based analysis.
As a candidate for a rapid detection of biomaterials, terahertz (THz) spectroscopy system can be considered with some advantage in non-destructive, label-free, and non-contact manner. Because ...protein-ligand binding energy is in the THz range, especially, most important conformational information in molecular interactions can be captured by THz electromagnetic wave. Based on the THz time-domain spectroscopy system, THz nano-metamaterial sensing chips were prepared for great enhancing of detection sensitivity. A metamaterial sensing chip was designed for increasing of absorption cross section of the target sample, related to the transmitted THz near field enhancement via the composition of metamaterial. The measured THz optical properties were then analyzed in terms of refractive index and absorption coefficient, and compared with simulation results. Also, virus quantification regarding various concentrations of the viruses was performed, showing a clear linearity. The proposed sensitive and selective THz detection method can provide abundant information of detected biomaterials to help deep understanding of fundamental optical characteristics of them, suggesting rapid diagnosis way especially useful for such dangerous and time-sensitive target biomaterials.
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