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This study presents a novel organocatalytic approach for direct modification of poly(ethylene oxide) (PEO) by attaching functional groups using C-H bond functionalization, yielding functionalized PEO with degradability and molecular delivery capabilities. Direct functionalization of PEO has been a challenging task due to the difficulty in finding versatile polymerization conditions that can accommodate various functional epoxides. The presented method overcomes these limitations and allows for a broad substrate scope including biologically active carboxylic acids such as ibuprofen and glycyrrhetinic acid. The modification process preserves the parent PEO structure throughout the highly reactive radical and oxocarbenium intermediate. The resulting functional PEO contains a degradable acetal unit, making it desirable for molecular delivery applications. Hydrolysis studies confirm the steady release of fragmented PEO and carboxylic acid. The drug-loaded PEO demonstrates cytoprotective activity in RAW264.7 cells stimulated with lipopolysaccharide (LPS). The hydrophobic drug moieties taken up by cells and released via the acid-triggered cleavage of acetal linkages in the acidic environment of endosomes. Crosslinked PEO is also demonstrated with a dicarboxylic acid, which loses its gel architecture upon contact with water. The presented method offers a versatile and efficient way to modify PEO, with potential applications in drug delivery and tissue engineering.

This paper describes a novel method for directly modifying poly(ethylene oxide) (PEO) by attaching functional groups using C-H bond functionalization. While existing methods for PEO modification, such as copolymerization and PEGylation, have limitations, direct functionalization of PEO has been challenging due to the difficulty in finding versatile polymerization conditions that can accommodate various functional epoxides. This study demonstrates a fully organocatalytic approach for direct PEO functionalization with carboxylic acids, resulting in a broad substrate scope that includes aromatic, aliphatic, and biologically active carboxylic acids such as ibuprofen and glycyrrhetinic acid. Importantly, our condition preserves the parent PEO structure throughout the highly reactive radical and oxocarbenium intermediate.

The ability to reduce the friction resistance between water and solid surface is one of the key functions of superhydrophobic surfaces. Reducing the frictional resistance between a solid surface and water is called drag reduction. This function is induced by the air layer formed at interface between the water and a superhydrophobic surface. The sustainability of the air layer is a key factor to induce stable drag reduction effect. Despite the importance of the air layers, only a few studies on the air layer sustainability have been reported. Therefore, in this study, various experiments on the air layer sustainability and drag reduction were carried out under the simulated underwater environment. Superhydrophobic PTFE surfaces with groove patterns having several hundred micrometers were applied in the experiments. As a result, it was possible to optimize groove pattern shape that can effectively maintain the air layer under hydrostatic pressure of 100 kPa. Furthermore, the effect of the groove patterns on the drag reduction was analyzed using water circulation system developed in this work.

Objectives: Uremic pruritus is common in patients with chronic kidney disease (CKD). The retention of uremic solutes is thought to be associated with uremic pruritus. Meanwhile, activation of protease-activated receptor-2 (PAR-2) has been suggested to play an important role in pruritus. The present study was performed to investigate the effects of uremic solutes on the expression of PAR-2 in the skin. Methods: Indoxyl sulfate (IS), p-cresol (PC), and uremic sera from CKD patients were used to stimulate PAR-2 expression in normal human epidermal keratinocytes (NHEKs). Also, NHEKs were additionally pretreated with soybean trypsin inhibitor to evaluate its inhibitory effect on PAR-2 expression. Patterns of cutaneous PAR-2 expression were investigated in skin samples from five CKD patients and CKD mice. Results: In NHEKs, IS, PC, and sera from CKD patients significantly induced PAR-2 mRNA and protein expression. Soybean trypsin inhibitor significantly decreased PAR-2 mRNA and protein expression in NHEKs treated with IS, PC, and CKD sera. NHEKs treated with IS and PC exhibited significant increases in protease activity. Skin from both CKD patients and mice exhibited marked upregulation of PAR-2 expression compared to control skin. Conclusions: Results from the present study suggest that uremic solutes either directly or indirectly affect PAR-2 expression in the skin of CKD subjects, potentially playing an important role in the pathogenesis of uremic pruritus.

The world has witnessed unimaginable damage from the coronavirus disease-19 (COVID-19) pandemic. Because the pandemic is growing rapidly, it is important to consider diverse treatment options to effectively treat people worldwide. Since the immune system is at the hub of the infection, it is essential to regulate the dynamic balance in order to prevent the overexaggerated immune responses that subsequently result in multiorgan damage. The use of stem cells as treatment options has gained tremendous momentum in the past decade. The revolutionary measures in science have brought to the world mesenchymal stem cells (MSCs) and MSC-derived exosomes (MSC-Exo) as therapeutic opportunities for various diseases. The MSCs and MSCExos have immunomodulatory functions; they can be used as therapy to strike a balance in the immune cells of patients with COVID-19. In this review, we discuss the basics of the cytokine storm in COVID-19, MSCs, and MSC-derived exosomes and the potential and stem-cell-based ongoing clinical trials for COVID-19. [BMB Reports 2020; 53(8): 400-412].

The shape of a projectile greatly affects its velocity when fired from a coil gun. A magnetic field is generated when the capacitor is discharged and current flows through a solenoid coil, and the magnitude of the resulting magnetic force depends on the projectile shape. A projectile has different amounts of drag depending on its shape. We analyzed the magnetic force and drag coefficient of a coil gun projectile according to its shape. The shape of the projectile was optimally designed to obtain high magnetic force and a small drag coefficient. ANSYS CFD was used to analyze the drag coefficient, and the electromagnetic simulation program Maxwell was used to analyze the magnetic force. The projectile design was optimized carried out using the commercial PIDO tool PIAnO. The optimal projectile was fabricated, and an experiment was conducted to measure the final velocity and verify the performance.

To investigate the effects of Brassicaceae cover crops on clover cyst nematode, Heterodera trifolii, 10 cultivars consisting of six of oil radish and four of white mustard were planted in the nematode infected field at Jeongseon city. Two months after planting, the cover crops were plow down and incorporated into the soil using rotavator, decomposed for 1 month, then transplanted kimchi-cabbages. After 70 days, the density of eggs inside of the cyst and the number of females in the soil were examined. As a result, the reproduction rates of eggs in each plots of Adios and Anaconda cultivars, which were 0.04 and 0.02, respectively, were greatly reduced. The number of females in the plots of above two cultivars showed means at 2.5 and 3.5 per 300 cm3 soil, which were lower than those of other plots. In addition, fresh weights of three plants in the two plots, which were 7.67 and 7.35 kg, were significantly higher than that of the control plot. Collectively, these results suggest that the two cultivars of Brassicaceae cover crops, Adios and Anaconda, could be used for reducing the cyst nematode density.

The relationship between the process condition of wire-drawing and the microstructural evolution during the subsequent annealing was investigated for the production of high-purity copper wires. Three wire-drawing process conditions were considered according to the reduction in the area per pass and the die angle, and their effects on the evolution of the grain structure and texture during annealing were investigated. Strain distributions, calculated using the finite element method, showed that the shear strain near the wire surface varies according to the process condition. The electron backscatter diffraction results indicate that the location on the cross-section of the wire, where secondary recrystallization initiates during annealing, is closely related to the shear strain during wire-drawing. Meanwhile, the effect of shear deformation on the grain structure and texture after primary recrystallization is insignificant. Drawing process conditions with a small reduction in the area per pass and die angle resulted in a relatively small shear strain and gave rise to the onset of secondary recrystallization at the central region of the wires. In contrast, the condition with a large reduction in the area per pass and die angle led to a high shear strain and the onset of secondary recrystallization at the peripheral region of the wire. The observed primary and secondary recrystallization behavior during annealing was explained from the viewpoint of dynamic material phenomena and inhomogeneity in the local recrystallization texture, regulated by the extent of shear deformation during wire-drawing.

Invar alloy possesses a uniquely low coefficient of thermal expansion, making it an ideal material for fine metal masks. To manufacture fine metal masks, Invar alloys are often cold-rolled, during which residual stress develops. Heat treatment is an effective means to control residual stress that develops within Invar sheets after cold rolling, but the treatment should be carried out with care. In this article, a comprehensive study on the effect of heat treatment on the residual stress, microstructure, and mechanical properties of a cold-rolled Invar sheet is reported. We show that while both recovery and recrystallization are effective means of reducing residual stress, substantial microstructural changes and, therefore, notable changes in mechanical properties and residual stress, occur after recrystallization. Moreover, residual stress release due to recrystallization can be affected by microstructure and texture prior to heat treatment as these factors play a significant role in recrystallization.

Recently, as the demands to improve automotive fuel efficiency grow, several attempts are being conducted on the development of lightweight automotive components using magnesium (Mg) alloy sheets having the highest specific strength among metal materials. In a window regulator module which is a switchgear that raises and lowers the automotive side window pane, the weight of the rail accounts for about 40 % of the total weight, while the production cost of the rail is about 10 % of the total cost, that is the weight reduction effect is higher than the cost burden. Therefore, the application of Mg alloy sheets to the window regulator rails is more likely to be commercialized. The aim of this study is to investigate the warm forming behavior of Mg alloy sheets in the manufacturing of window regulator rails at the temperature range from 150 to 250 °C. AZ31B Mg alloy sheets with a thickness of 1.4 mm were used, and their mechanical properties were evaluated at the warm temperature range. The warm forming behavior was predicted by the finite element simulation. Based on the simulation results, the Mg alloy window regulator rail was successfully manufactured without fracture using the warm forming.

Cigarette smoking is a major cause of lung cancer. Although tobacco smoking-induced genotoxicity has been well established, there is apparent lack of abundance functional epigenetic effects reported On cigarette smoke-induced lung carcinogenesis. The aim of this study was to determine effects of intratracheal administration of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) utilizing target gene expression DNA methylation patterns in lung tissues of mice following twice weekly for 8 weeks treatment. An unbiased approach where genomic regions was undertaken to assess early methylation changes within mouse pulmonary tissues. A methylated-CpG island recovery assay (MIRA) was performed to map the DNA methylome in lung tissues, with the position of methylated DNA determined using a Genome Analyzer (MIRA-SEQ). Alterations in epigenetic-regulated target genes were confirmed with quantitative reverse transcription-PCR, which revealed 35 differentially hypermethylated genes including Cdkn1C, Hsf4, Hnf1a, Cdx1, and Hoxa5 and 30 differentially hypomethylated genes including Ddx4, Piwi1, Mdm2, and Pce1 in NNK-exposed lung tissue compared with controls. The main pathway of these genes for mediating biological information was analyzed using the Kyoto Encyclopedia of Genes and Genomes database. Among them, Rssf1 and Mdm2 were closely associated with NNK-induced lung carcinogenesis. Taken together, our data provide valuable resources for detecting cigarette smoke-induced lung carcinogenesis.

In this paper, the extrusion process of titanium seamless tubes was studied using several finite element (FE) analyses. First, the finite element result was compared with experimental extrusion data acquired to validate the current analysis. Then, the effect of design parameters of the die shape was numerically analyzed using commercial FE software, Forge NxT, for the metal forming process. Elastic FE analyses were also conducted for dies to analyze the maximum principal stress that affects the early fracture of dies during the extrusion process and the maximum von Mises stress that causes the severe deformation of dies. Consequently, the effect of the corner radius at the exit and land length on the extrusion load and die stress is negligible compared to that of the corner radius at the entrance and die angle. Finally, we suggested a die angle of 60° and a corner radius at the die entrance between 10 and 15 mm as an optimal design for the current extrusion process.

In molten carbonate fuel cell (MCFC) systems, it is known that the shape of corrugated plates has a significant influence on performance, durability, and cost. A corrugated plate with a repeating open trapezoidal-shaped slot supports membrane electrode assembly and provides a gas flow channel. To increase the efficiency of the MCFC, the slot between the corrugated and center plates has a relatively large contact length. However, increasing the contact length of the slot increases the risk of necking or fracture generation at the corner of the slot. Therefore, we focus on the development of forming technology of corrugated plate which has large contact length of slots without any necking or fracture. To this end, numerical simulation was conducted to determine the appropriate process and tool design. In the simulation, to capture shear fracture during the forming process of slots, the normalized Cockroft–Latham ductile fracture model was used. The critical value for slitting and fracture was evaluated by comparing the deformed shapes in the slitting plane obtained from experimental and simulation results. Based on simulation results, a reasonable design concept of the two-stage forming process was suggested to increase the contact length of the slot without necking or fracture. In addition, the experiment results confirmed the validity of the proposed forming process and tool design.

This paper describes a fully integrated 8-channel front-end module (FEM) single chip IC fabricated with 45-nm RFSOI CMOS process technology for 5G mm-Wave application supporting n257/258/261 triple bands. Its silicon area is 4.29mm × 2.76mm which is comprised of high efficiency Doherty topology power amplifier, low noise amplifier, T/Rx switch, MIPI interface controller and so on. To address module assembly area limitation on the mm-wave antenna PCB, an ultra-thin Embedded Die Substrate (EDS) package is adopted and realizes virtually Zero-space integrate the FEM die in the middle of PCB. The average output power of the Tx is 17dBm with 22% PAE at 5.9% EVM and Rx NF is 3.4dB at the 27GHz.

We have investigated the effect of initial microstructures on the change in critical current density (Jc) of Nb-46.5 wt%Ti (NbTi) superconducting material. It is well known that α-Ti phases distributed in NbTi material act as a flux pinning center, resulting in an improvement in critical current density. Therefore, it is crucial to obtain the grain-refined microstructure, which is strongly related with precipitation of uniformly distributed fine α-Ti phases and higher volume faction of α-Ti phases, as α-Ti phases are precipitated at the grain boundaries and triple points during heat treatments. Therefore, in order to characterize the effect of initial microstructure of NbTi on critical current density, different initial microstructures were obtained by applying equal channel angular pressing (ECAP) and hot rolling with different strains. It was revealed experimentally that hot rolling with a higher strain is efficient for obtaining the initial microstructure, which has equiaxed fine grains of β-NbTi with the aid of dynamic recrystallization, and which is helpful for precipitating fine α-Ti phases during intermediate heat treatment. Furthermore, it was confirmed that critical current density can be enhanced by obtaining a smaller α-Ti phase, a higher aspect ratio of α-Ti phase, a higher volume fraction of α-Ti phase and a ribbon-like folded α-Ti phase.

The critical current density (Jc), which is a major performance parameter of low temperature superconducting Nb-46.5 wt%Ti wire, can be improved by uniformly dispersed fine α-Ti precipitates since they serve as a flux pinning center. The high volume fraction of α-Ti precipitates at grain boundary intersections can be achieved by repetitive large deformation and intermediate heat treatments. For this aim, we investigated effect of severe plastic deformation of Nb-46.5 wt%Ti billet on the changes in microstructure and Jc by assigning equal channel angular process (ECAP) followed by groove rolling and drawing. In addition, intermediate heat treatments with different heating condition and holding time after each process were assigned to precipitate the fine α-Ti. It was observed that the curled flow lines like shear bands with the highly dense dislocations were formed after ECAP leading to recrystallization and the high volume fraction of α-Ti after subsequent heat treatment. The additional plastic deformation by groove rolling and drawing increased the volume fraction of the α-Ti and the aspect ratio of its shape. As a result, the critical current density at the lower range of magnetic field was enhanced with increasing the number of ECAP pass.

In this study, the mechanical properties of a high-strength laminated vibration damping steel sheet (LVDSS) with stretch-dominated deformation behavior were characterized and successfully applied to formability prediction. The high-strength LVDSS was fabricated with dual-phase 590 steel sheets as outer skins and polymeric adhesive layer as a core via roll bonding. The uniaxial and biaxial mechanical behaviors were evaluated by performing uniaxial tension and in-plane biaxial tension tests, respectively, while the forming limit was investigated by conducting punched dome tests. Then, based on the experimental data, the mechanical properties of the LVDSS were characterized, viz., the hardening curve, yield function, and forming limit curve. As an example of LVDSS application, a square cup drawing test was conducted and a dashboard prototype was fabricated using an LVDSS, and the deformation and failure behaviors were successfully predicted via a finite element simulation performed by inputting the characterized mechanical properties.

This paper deals with the stability of industrial robot arms with six axes and six degrees of freedom. The robot arm used was IRB120, a product of ABB company, which is used in the real industry, by using the commercial “DAFUL” which is a simulation program that can analyze the dynamic behavior. DAFUL was applied to the robot arm to control the motion by applying the load to the robot arm and then the structural analysis of the robot arm was performed during the analysis time. As a result of the analysis of the robot arm, the stress and displacement acting on the elliptic model and the acting torque and force were analyzed. Based on the analysis results, stability was checked with reference to IRB120 product catalog.

The importance of oil–water separator has increased due to environmental pollution caused by marine accidents. Many studies related to fabrication method of superhydrophobic surface have been conducted because those functional surfaces are an important component used in oil and water separators. However, processes that can be applied to large area and mass production still exist as limitations. In this paper, superhydrophobic surfaces were fabricated on polytetrafluoroethylene (PTFE) surface by hot imprinting. To impart rough surface morphology to PTFE surface, hot imprinting process using an electrical discharge textured (EDT) mold was conducted. It was found that undercut of a discharge crater on the EDT surface induced tensile deformation of PTFE surface during the hot imprinting process resulting in microfibril development. As a result, PTFE surface had rough morphology consisting of replicated EDT surface and microfibril network. Imprinted PTFE sheets showed high water contact angles about 154.3° with low contact angle hysteresis about 1.4°. Additionally, the effects of process temperature and roughness of the EDT mold on microfibril formation were investigated. It was found that microfibril formation is activated when the process temperature reaches glass transition temperature (115 °C) of PTFE. The PTFE sheets for oil–water separation were prepared by hot imprinting and followed by additional drilling process. The optimal hole diameter with respect to efficiency of oil–water separation was determined through experiments and separation of oil and water was effectively conducted.