Microstructure-Based Modeling and Estimation of Mechanical Properties of High-Carbon Steel

Herein, attempts are made to estimate the mechanical properties using microstructure-based finite element (FE) modeling and validate these results with the experimental results. The two high-carbon steel specimens are hot-rolled and air-cooled to develop ferrite–pearlite microstructures. Different characterizations are utilized to observe microstructures as well as Vickers hardness and tensile tests are carried out to determine the mechanical properties. Two high-resolution scanning electron micrographs are chosen for representative volume element-based FE analyses for modeling the mechanical behavior of ferrite–cementite microstructure. Object-oriented finite elements (OOF2) and Abaqus FEA 6.14 software are used to estimate the elastic and elastoplastic behavior assuming plane stress conditions. The correlation between cementite lamellae orientation and the predicted elastoplastic properties is investigated and compared with the experimental results. The influence of image size and mesh size on the predicted true stress–true strain behavior is discussed. The hard and brittle cementite lamellae face maximum stress while the softer ferrite matrix experiences maximum strain. It is found that strain accumulation is maximum at the interfaces of ferrite and cementite. These findings are further validated by the microvoid and crack initiation spots in the fracture surface and subsurface micrographs of broken tensile specimens.     

Reactions of phenolic ester alcohol with aliphatic isocyanates—transcarbamoylation of phenolic to aliphatic urethane: A 13C‐NMR study

Reactions of aliphatic isocyanates with a phenolic ester alcohol (PHEA) were investigated using ¹³C‐NMR spectroscopy. PHEA has two reactive sites: a phenolic  OH group and a secondary aliphatic  OH group. Both  OH groups react with the isocyanate groups. With an organotin catalyst, dibutyltin dilaurate (DBTDL), the aliphatic  OH group reacts first. With a tertiary amine catalyst, 1,4‐diazabicyclo[2.2.2]octane (DABCO), or triphenylphosphine (Ph₃P) or even in the absence of a catalyst at room temperature (RT) the phenolic  OH group reacts first. With the organotin catalyst, the reactions are generally complete in a day at RT. With DABCO or triphenylphosphine or DNNDSA catalysts, the reactions are almost complete only in 3–4 days at RT in ethyl acetate or acetonitrile. Uncatalyzed reactions are slower. With an acid catalyst such as dinonylnaphthalenedisulfonic acid (DNNDSA), both  OH groups react with the isocyanate. When equimolar quantities of PHEA and hexamethylenediisocyanate (HDI) polymerize at RT or reflux in the presence of a catalyst, both  OH groups react, with the phenol reacting slowly. Upon refluxing, the phenolic  OH‐based urethane slowly rearranges (transcarbamoylation) to the aliphatic  OH‐based urethane. DABCO and Ph₃P catalysts effect this rearrangement at a much slower rate than does the acid catalyst. In the presence of a catalytic amount of DBDTL in a refluxing solvent, this rearrangement is complete in 2 h. By refluxing the phenolic–OH‐based urethane in isopropanol, the mechanism of transcarbamoylation was found to be intermolecular. The mechanism is likely to involve deblocking of the phenolic urethane and subsequent reaction of the isocyanate generated, with the aliphatic  OH group. This conclusion was confirmed by differential scanning calorimetry (DSC) experiments. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2212–2228, 2000     

Enhanced U-Net segmentation with ensemble convolutional neural network for automated skin disease classification

Knowledge and Information Systems - In recent years, skin-related problems induce psychological problems and also injure physical health, particularly if the patient’s face was disfigured or...     

Improved mechanical stability of indium zinc tin oxide based flexible transparent electrode through interlayer treatment

Due to the significant growth of the market for numerous flexible electronic devices, demand for mechanically stable indium zinc tin oxide (IZTO) based flexible transparent electrodes has recently expanded substantially. So, we have attempted to increase the mechanical stability of an IZTO based flexible transparent electrode by forming an ultrathin interlayer of an organic semiconductor polystyrene sulfonate doped polyaniline (PANI:PSS). According to the results of the systematic investigation, the PANI:PSS treated IZTO film can preserve 97.50% of its initial average transmittance (AVT) value (83.07%) after 20,000 bending cycles, but the bare IZTO film can retain only 89.00% of its initial AVT value (86.40%) after the same treatment. Furthermore, the PANI:PSS treatment has benefited in the reduction of IZTO film sheet resistance from 17.38 to 16.91 Ω/sq. Scanning electron microscopy images have indicated that the presence of a PANI:PSS interlayer on the IZTO film prevents the formation of fractures on the inorganic IZTO layer when mechanical stress is applied.     

Surface Reconstruction of Ni–Fe Layered Double Hydroxide Inducing Chloride Ion Blocking Materials for Outstanding Overall Seawater Splitting

Generation of hydrogen fuel via electrochemical water splitting powered by sustainable energy, such as wind or solar energy, is an attractive path toward the future renewable energy landscape. However, current water electrolysis requires desalinated water resources, eventually leading to energy costs and water scarcity. The development of cost-effective electrocatalysts capable of splitting saline water feeds directly can be an evident solution. Herein, a surface reconstructed nickel-iron layered double hydroxide (NF-LDH) is reported as an exceptionally active and durable bifunctional electrocatalyst for saline water splitting without chloride corrosion. The surface reconstructed NF-LDH consists of Ni₃Fe alloy phase interconnected in a 2D network in which an ultrathin (≈2 nm) and low-crystalline NiFe (oxy)hydroxide phase are formed on the surface. The NiFe (oxy)hydroxide phase draws large anodic current densities, satisfying the level of practical application, while the Ni₃Fe alloy phase is simultaneously responsible for the high catalytic activity for cathodic reactions and superior corrosion resistance. The surface reconstructed NF-LDH electrode can be easily fabricated in a large electrode area (up to 25 cm²) and can successfully produce hydrogen fuels from saline water powered by the laboratory-made low-intensity photovoltaic cell.