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The main focus in electronics field in recent years is transitioning from rigid and performance-focused studies to light-weight, portable, and stretchable materials, that could perform wide variety of tasks without encountering the materials failure barrier due to stiff mechanical properties. Material design requires careful balance between mechanical and electrical properties that ensures functional device even at significant deformations. There has been continuous thrust in developing novel materials to be applied for soft electronics, and majority of the studies have been focused on using polymer blend to leverage the deformability and charge conduction at the same time. This is enabled by functional polymeric ionic liquids (PILs) that has charge conducting and light-responsive properties while having malleability at ambient temperature. The rubbery properties of PIL adds various functionality, such as deformability for soft electronics that conducts either electron or ions, and light-triggered actuations. In this Dissertation, the overall PIL design strategy in polymeric structure, characterization, and applications are laid out to rationalize structure-property relationship and how that results in targeted mechanical, electrical, and light-absorbing properties.

The objective of this research is to develop an environmentally friendly construction material, referred to as the ultralow-binder-content (UBC) composite. Compared to ordinary portland cement, a UBC composite has a much lower binder content, which helps decrease carbon emission, save energy, minimize materials cost, and face the challenge of the declining supply of class F fly ash. In general, the UBC composites use regular aggregates as the filler, such as sand, crushed limestones, and gravels. The binder can be a polymer (e.g., epoxy), a geopolymer, or a combination thereof. For special applications, the filler can be carbon powders. The key step in the processing procedure is the compaction self-assembly (CSA). It takes advantage of a relatively high pressure to compress the filler particles, which promotes the binder dispersion and favorably controls the stoichiometry. In a produced UBC composite, the binder is not continuous, but aggregated at the most critical load-carrying microstructural sites as micro-agglomerations. The CSA operation can be performed quasi-statically or dynamically. For large samples, the compaction can be completed section by section.

Solvent rinse treatments using polar methanol (MeOH) and nonpolar n-hexane have been developed for controlling material concentration gradients along the longitudinal direction of non-fullerene acceptor-based bulk heterojunction (BHJ) films comprised of electron donor polymer, PBDB-T and acceptor, ITIC-m. Before the used solvents (chlorobenzene with 1 vol.% DIO) were completely evaporated, ITIC-m rich domains were formed at the top surface of the BHJ films after they were rinsed with MeOH, as evidenced by water contact angle, atomic force microscopy, time-of-flight secondary ion mass spectroscopy, which led to enhanced electron transport in the conventional structure of organic solar cells (OSCs). In contrast, after rinsing with n-hexane, ITIC-m rich domains were formed at the bottom surface of the films, which improved electron transport in the inverted structure OSCs. The enhanced carrier transports increased the PCEs (11.80% and 11.15%) in both conventional and inverted OSCs by 10.29% and 10.35% compared with control devices. The versatile control of material concentration gradients is determined to be feasible owing to the chemical interaction of the used substrates (glass, PEDOT:PSS, and ZnO) and rinsing solvents.

We report on comparative atom probe tomography investigations of I³/I³â�²-forming Co-12Ti-4Mo-Cr alloys. Moderate additions of Cr (2 and 4 at) reduced the I³/I³â�² lattice misfit and increased the I³â�² volume fraction of a Co-12Ti-4Mo alloy significantly. These microstructural changes were accompanied by changes in the elemental partitioning between I³ and I³â�² and site-occupancy in I³â�². Spatial distribution maps revealed that Mo occupied both Co and Ti sub-lattice sites in I³â�². In agreement with the experimental data, thermodynamic calculations predicted a stronger tendency for Mo to occupy the Co-sites than for Cr and an increase in Cr fraction on the Ti-sites with increasing Cr content. Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of the Microscopy Society of America.

Crack width is a critical factor influencing the behaviour and performance of a roller-compacted concrete pavement (RCCP) because wide cracks can result in water infiltration and poor load transfer, leading to faulting, excessive deflection and further cracking. The crack width may be affected by temperature changes, concrete drying shrinkage and creep, crack spacing and the base material. An empirical equation to predict the crack width has been proposed by the American Association of State Highway and Transportation Officials (Aashto). However, this equation is quite simplified because a uniform strain distribution is assumed along the slab length. In this work, a mechanistic approach to predict the crack width in RCCP was developed using a three-dimensional finite-element model considering a non-linear friction model between the slab and the base. Moreover, the effect of concrete creep on the crack width was incorporated using the effective modulus method. The mechanistic model was validated with crack width data from two full-scale RCCP test sections in South Korea. The mechanistic model showed good agreement with the field data, whereas the Aashto equation tended to over-predict the crack widths. The proposed model is thus helpful to predict the crack width in a concrete pavement slab for given environmental conditions, slab geometry, material properties and base material.

Porous ceramics have the advantages of low density, low thermal conductivity, and excellent mechanical properties. One of the scalable methods for manufacturing porous ceramics is the replica method, which provides the advantage of high porosity and the critical disadvantage of low mechanical strength. To overcome this shortcoming, mullite (3Al2O3·2SiO2) whiskers, which have excellent thermal stability and high mechanical strength, were introduced in porous ceramic structure. The mullite whiskers were prepared using Al2O3, kaolin, frit, and MoO3 composition. The addition of MoO3 lowered the mullitization temperature, and the mullite whiskers could be grown at 1100–1400 °C. The morphologies and crystal structures of the mullite whiskers with various the annealing temperatures and MoO3 contents were investigated in detail. The mullite whiskers, which contained 20 wt% MoO3 and was annealed at 1300 °C, showed the highest aspect ratio of 137 with the average length of 46.6 μm and average thickness of 0.34 μm. The compressive strength and porosity of the porous ceramic sample with these mullite whiskers were 0.97 MPa and 87.5%, which were also the highest values.

Hexagonal porous optical fiber without a central defect is proposed and numerically analyzed with the finite element method (FEM) for transmitting terahertz (THz) electromagnetic wave pulse. In experiments, the transmission characteristics of polytetrafluoroethylene (PTFE) hexagonal porous optical fibers were measured using a THz time-domain spectroscopy (THz-TDS) system. To precisely estimate the effective material loss (EML), we measured the refractive index and absorption coefficient of PTFE in the THz range to use them in FEM analyses, and the EML of the porous fiber was estimated to be lower than that of a bulk rod as large as by a factor of 2 in the frequency range from 0.1 to 0.33 THz. In experiments, we measured the transmission characteristics of both the porous fibers and the bulk rod, to confirm a significant improvement in THz wave transmission nearly by an order of magnitude in the 6G telecommunication window, showing a better performance than theoretical estimations.

When designing organic semiconductors, side-chain engineering is as important as modifying the conjugated backbone, which has a significant impact on molecular ordering, morphology, and thus electronic device performance. We have developed three dicyanovinyl-end-capped donor-acceptor diketopyrrolopyrrole-based n-type small molecules (C2C9CN, SiC4CN, and EH4PCN) bearing an identical length of alkyl spacer yet different end-functionalized side chains (i.e., alkyl-, siloxane-, and phosphonate-end pendants). The effects of the end-functionalized side chains on the intrinsic molecular properties, microstructure, and charge transport of the small-molecule series were investigated. In comparison with the alkyl-end side chains, incorporating siloxane-end side chains into the backbone facilitates 2D edge-on oriented high intergrain connectivity/crystallinity and compatibility with the substrate surface, whereas the phosphonate-end analogues have an adverse effect on the film-forming quality due to high polarity. Thereby, an organic field-effect transistor fabricated by SiC4CN shows the best electron mobility up to 1.59 × 10-1 cm2 V-1 s-1 along with a high current on/off ratio >105. This study contributes to our understanding of the role of the end-functionalized side chains (e.g., the effects of polarity and bulkiness of the end groups) for the development of high-performance semiconductors.

In this study, utilizing metallocene and organosulfur chelating agent, an innovative synthetic route was developed towards electrochemically activated transition metal sulfides entrapped in pyridinic nitrogen-incorporated carbon nanostructures for superior oxygen evolution reaction (OER). Most importantly, the preferential electrochemical activation process, which consisted of both anodic and cathodic pre-treatment steps, strikingly enhanced OER and long-lasting cyclic stability. The substantial increase in OER electrocatalytic activity of Ni9 S8 /Ni3 S2 -NC and Co9 S8 -NC during the activation process was mainly attributed to the increase of faradaic active site density on the catalytic layer resulting from the reconstruction of catalytic interfaces. It was also found that Fe-based metallocene [ferrocene (Fc)]-incorporation in the Co9 S8 -NC and Ni9 S8 /Ni3 S2 -NC nanostructures significantly boosted the OER activity. Thus, the combined effects of Fc-incorporation and the electrochemical activation process reduced the overpotential to about 115 and 95 mV on the Ni9 S8 /Ni3 S2 -NC and Co9 S8 -NC nanostructures to derive a current density of 10 mA cm-2 , respectively. Notably, Fc-Ni9 S8 /Ni3 S2 -NC electrocatalysts required very small overpotentials of around 222, 244, and 280 mV to acquire the current densities of 10, 20, and 50 mA cm-2 , respectively. This work opens up a new avenue for superior OER electrocatalysts by the utilization of metallocene and the preferential electrochemical activation process.

Herein, we present a novel low-temperature polycrystalline silicon (LTPS) thin-film transistor (TFT) pixel circuit for a micro light-emitting diode ( $\mu $ LED) display based on pulse width modulation (PWM). By adopting PWM, we could achieve 10-bit gray levels of $\mu $ LED without wavelength shift, which is a challenge in the realization of $\mu $ LEDs. Furthermore, the proposed circuit compensated for the variation in threshold voltage ( ${V}_{{\text {TH}}}$ ) without an external sensing system. We simulated the error rate of the $\mu $ LED emission time of the proposed pixel circuit depending on the VTH change. We measured the wavelength shift of the $\mu $ LED using the fabricated circuit. This shift in PWM was smaller than that in pulse amplitude modulation (PAM). Consequently, the proposed pixel circuit could overcome screen distortions caused by color shifts of $\mu $ LED displays using PWM techniques.

A port injection engine that supplies hydrogen to the intake manifold or port exhibits a low intake air amount and torque output. The torque output is limited by backfire. In the present study, the performance and efficiency of a port injection-type hydrogen engine using the fuel injector of a natural gas engine is investigated at various engines speeds under wide open throttle conditions and two operation strategies, i.e., limiting nitrogen oxide emission and maximizing the torque. The increase in electrode temperature is reduced by increasing the heat rating number of the spark plug or reducing the ignition energy applied to the spark plug. Even when the ignition energy is reduced, as the minimum ignition energy of hydrogen is very low, it does not eliminate backfire. However, when a cold-type spark plug is used, backfire is effectively suppressed, resulting in an increase in the maximum torque and a decrease in efficiency.

An in-situ analysis of local strain accommodation on transformation induced plasticity (TRIP) aided multi-phase steel was performed with a correlative application of characterization techniques such as digital image correlation (DIC), electron backscatter diffraction (EBSD), and micro-mechanical testing. The local strain on the complex microstructure of the multi-phase steel was measured during a tensile test using an innovative DIC method (which does not employ artificial patterns), in conjunction with a scanning electron microscope. The constituent phases of the examined surface were identified by postprocessing implemented on the EBSD maps. This was further verified by nano-indentation, consequently enabling systematic and quantitative analyses of the strain partitioning between the phases. Soft acicular ferrite accommodated the largest strain with sites of intense strain localization around the hard, neighboring martensite. The retained austenite transformed gradually into martensite because of the applied strain and caused strain localization in the neighboring acicular ferrite. This verified that DIC method proposed in this study enables precise and effective data collection at the interfaces between different phases that could have certainly been blocked by the DIC patterns in the conventional method.

Tungsten as a material exhibits broad and increasingly important applications; however, the characterization of its ductile-to-brittle transition (BDT) is currently limited to large-scale scenarios and destructive testing. In this study, we overcome this challenge by implementing small-scale techniques to provide a comprehensive understanding of the BDT behavior of pure tungsten. In order to predict the failure mode at various temperature ranges, the practical fracture analysis diagram has been proposed to describe the resistance to shear flow and cracking behavior with temperature. High temperature nano-indentation tests have provided the inherent mechanical responses corresponding to the maximum shear stress at various temperatures, which is required for dislocation activities in an atomic scaled activation volume. On one hand, atomistic simulations have provided the temperature dependence of brittle fracture stress, where the atomic bonds break due to intergranular or intragranular fracture. We considered four tungsten specimens having various microstructures prepared using different processing conditions of cold-rolling and post-annealing, and their BDT ranges were inferred using the obtained fracture analysis diagram with the statistical data processing. The fracture analysis diagram of each specimen obtained were compared with the direct observation of fracture responses in macroscopic mechanical tests, which conclusively indicated that the small-scale inherent mechanical properties are greatly relevant to the macroscopic BDT behavior in pure tungsten. Based on the BDT estimations by small-scale characterization, we provided further insights into the factors affecting the BDT behavior of tungsten, focusing on the contributions of different types of dislocations.

Few atom thick, twisted bilayer graphene (tBLG) possesses a rotation angle (θ) dependent van Hove singularity (vHs). Fine-tuning vHs serves a potential method to enhance charge transfer (CT) in surface enhanced Raman spectroscopy. This study shows that tBLG having a specific θ promotes as high as a 1.7 times enhancement of the Raman signals of copper phthalocyanine (CuPc) as compared to that caused by single layer graphene (SLG). The results of a combination of reflection imaging spectroscopy and widefield Raman provide spatial and spectral information about both tBLG with θ ranging from 10.9 to 13.7° and the corresponding vHs. Comparison of Raman spectra of CuPc in presence and absence of tBLG demonstrates that a significant enhancement of certain CuPc vibrational modes occurs when the underlying tBLG possesses a θ = 12.2°, showing as high as 6.8 and 1.7 times enhancements of certain vibrational mode as compared to those of CuPc on bare and SLG substrates, respectively. Theoretical calculations indicate that a match between the energies of vHs of tBLG with those of frontier orbitals of CuPc facilitates CT from the distant SLG to CuPc.

The chemical vulnerability of sulfide solid electrolyte (SE) materials to organic polar solvents complicates the wet-slurry fabrication of sheet-type electrodes and SE films for practical all-solid-state Li batteries (ASLBs). Moreover, the disruption of interfacial Li+ conduction by binders is problematic. This could be relieved by blending with liquid electrolytes but at the expense of the ASLBs’ thermal stability. In this study, a new tactical approach to hybridize sulfide SEs with thermally stable and slurry-fabricable dry polymer electrolyte (DPE)-type binders is reported. Along with their practicability, ester solvents bearing bulky hydrocarbons, such as benzyl acetate, dissolve both polymers and Li salts (e.g., LiTFSI) while undamaging sulfide SEs. The use of the DPE-type binder, NA-LiTFSI (NA: nitrile butadiene rubber-poly(1,4-butylene adipate)), for LiNi0.70Co0.15Mn0.15O2 (NCM) electrodes significantly improves their electrochemical performance at 30 °C. Moreover, NA-LiTFSI is highly functional at 70 °C (from 180 to 200 mA h g−1 and from 84.2 to 91.8% for initial Coulombic efficiency) and applicable for other electrodes, such as graphite (from 265 to 330 mA h g−1) and Li4Ti5O12, which is in stark contrast to the solvate ionic liquid-type binder Li(G3)TFSI. Finally, pouch-type NCM/graphite ASLBs employing electrodes made of NA-LiTFSI binders were also fabricated.

The effect of the material hardening model of the canister on a finite element vertical cask drop simulation is investigated for the strain-based acceptance evaluation. Three different hardening models are considered in this paper: the isotropic hardening model, the strain rate-dependent Johnson-Cook (J-C) hardening model, and the modified J-C model which are believed to be the most accurate. By comparing the results using the modified J-C model, it is found that the use of the J-C model provides similar or larger stresses and strains depending on the magnitudes of the strain and strain rate. The use of the isotropic hardening model always yields larger stresses and strains. For the strain-based acceptance evaluation, the use of the isotropic hardening model can produce highly conservative assessment results. The use of the J-C model, however, produces satisfactory results.

In this study, water-dispersible graphitic carbon nitride (g-C3N4) photocatalysts were successively prepared through the chemically oxidative etching of bulk g-C3N4 that was polymerized thermally in different calcination atmospheres such as air, CO2, and N2. The different calcination atmospheres directly influenced the physicochemical and optical properties of both bulk and water-dispersible g-C3N4, changing the photocatalytic degradation behavior of methylene blue (MB) and tetracycline hydrochloride (TC-HCl) for water-dispersible g-C3N4. The bubble-burst process in the thermal polymerization of thiourea produced defective edges containing C=O groups that preferred substituting the C-NHx groups over bulk g-C3N4. In the oxygen-free N2 atmosphere among the different calcination atmospheres, more C=O functional groups were generated on the defective edges of bulk g-C3N4, resulting in the highest N vacancy of the tri-s-triazine structure. During the successive chemical oxidation, S- or O-containing functional groups were introduced onto water-dispersible g-C3N4. The water-dispersible g-C3N4 photocatalyst from the oxygen-free N2 atmosphere (NTw) contained the most O- and S- functional groups on the g-C3N4 surface. Consequently, NTw exhibited the highest photocatalytic activity in the MB and TC-HCl photodegradation because of its slowest recombination process, which was ascribed to the unique surface properties of NTw such as abundant functional groups on the defective edges and N-deficient property.

Jung Suk Kim,1,* Fakhar ud Din,2,* Sang Min Lee,1,* Dong Shik Kim,1 Mi Ran Woo,1 Seunghyun Cheon,1 Sang Hun Ji,1 Jong Oh Kim,3 Yu Seok Youn,4 Kyung Taek Oh,5 Soo-Jeong Lim,6 Sung Giu Jin,7 Han-Gon Choi1 1College of Pharmacy, Hanyang University, Ansan, South Korea; 2Department of Pharmacy, Quaid-I-Azam University, Islamabad, Pakistan; 3College of Pharmacy, Yeungnam University, Gyongsan, South Korea; 4School of Pharmacy, Sungkyunkwan University, Suwon, South Korea; 5College of Pharmacy, Chung-Ang University, Seoul, South Korea; 6Department of Bioscience and biotechnology, Sejong University, Seoul, South Korea; 7Department of Pharmaceutical Engineering, Dankook University, Cheonan, South Korea*These authors contributed equally to this workCorrespondence: Sung Giu Jin; Han-Gon Choi Tel +82 41-550-3558; +82 31-400-5802Fax +82 41-559-7945; +82 31-400-5958Email sklover777@dankook.ac.kr; hangon@hanyang.ac.krBackground: The purpose of this study was to screen various drug delivery systems for improving the aqueous solubility and oral bioavailability of sildenafil. Three representative techniques, solid self-nanoemulsifying drug delivery systems (SNEDDS), amorphous microspheres and crystalline microspheres, were compared.Methods: Both microspheres systems contained sildenafil:Labrasol:PVP at a weight ratio of 1:1:6. The amorphous microspheres were manufactured using ethanol, while crystalline microspheres were generated using distilled water. Liquid SNEDDS was composed of sildenafil:Labrasol:Transcutol HP:Captex 300 in the ratio of 1:70:15:15 (w:w:w:w). The solidification process in SNEDDS was performed using HDK N20 Pharma as a solid carrier.Results: The amorphous microspheres appeared spherical with significantly decreased particle size compared to the drug powder. The crystalline microspheres exhibited a rough surface with no major particle-size difference compared with sildenafil powder, indicating that the hydrophilic excipients adhered to the sildenafil crystal. Solid SNEDDS presented a smooth surface, assuming that the oily liquid was adsorbed to the porous solid carrier. According to the physicochemical evaluation, the crystalline state maintained in crystalline microspheres, whereas the crystal state changed to amorphous state in other formulations. Amorphous microspheres, crystalline microspheres and solid SNEDDS produced about 79, 55, 82-fold increased solubility, compared to drug powder. Moreover, the prepared formulations provided a higher dissolution rate (%) and plasma concentration than did the drug powder (performance order; solid SNEDDS ≥ amorphous microspheres ≥ crystalline microspheres > drug powder). Among the formulations, solid SNEDDS demonstrated the highest improvement in oral bioavailability (AUC; 1508.78 ± 343.95 h·ng/mL).Conclusion: Therefore, solid SNEDDS could be recommended as an oral dosage form for enhancing the oral bioavailability of sildenafil.Keywords: sildenafil, amorphous microspheres, crystalline microspheres, solid self-nanoemulsifying drug delivery system, aqueous microenvironment, oral bioavailability

Purpose Recently, high-precision radiotherapy systems have been developed by integrating computerized tomography or magnetic resonance imaging to enhance the precision of radiotherapy. For integration with additional imaging systems in a limited space, miniaturization and weight reduction of the linear accelerator (linac) system have become important. The aim of this work is to develop a compact medical linac based on 9.3 GHz X-band RF technology instead of the S-band RF technology typically used in the radiotherapy field. Methods The accelerating tube was designed by 3D finite-difference time-domain and particle-in-cell simulations because the frequency variation resulting from the structural parameters and processing errors is relatively sensitive to the operating performance of the X-band linac. Through the 3D simulation of the electric field distribution and beam dynamics process, we designed an accelerating tube to efficiently accelerate the electron beam and used a magnetron as the RF source to miniaturize the entire linac. In addition, a side-coupled structure was adopted to design a compact linac to reduce the RF power loss. To verify the performance of the linac, we developed a beam diagnostic system to analyze the electron beam characteristics and a quality assurance (QA) experimental environment including 3D lateral water phantoms to analyze the primary performance parameters (energy, dose rate, flatness, symmetry, and penumbra) The QA process was based on the standard protocols AAPM TG-51, 106, 142 and IAEA TRS-398. Results The X-band linac has high shunt impedance and electric field strength. Therefore, even though the length of the accelerating tube is 37 cm, the linac could accelerate an electron beam to more than 6 MeV and produce a beam current of more than 90 mA. The transmission ratio is measured to be approximately 30% ~ 40% when the electron gun operates in the constant emission region. The percent depth dose ratio at the measured depths of 10 and 20 cm was approximately 0.572, so we verified that the photon beam energy was matched to approximately 6 MV. The maximum dose rate was measured as 820 cGy/min when the source-to-skin distance was 80 cm. The symmetry was smaller than the QA standard and the flatness had a higher than standard value due to the flattening filter-free beam characteristics. In the case of the penumbra, it was not sufficiently steep compared to commercial equipment, but it could be compensated by improving additional devices such as multileaf collimator and jaw. Conclusions A 9.3 GHz X-band medical linac was developed for high-precision radiotherapy. Since a more precise design and machining process are required for X-band RF technology, this linac was developed by performing a 3D simulation and ultraprecision machining. The X-band linac has a short length and a compact volume, but it can generate a validated therapeutic beam. Therefore, it has more flexibility to be coupled with imaging systems such as CT or MRI and can reduce the bore size of the gantry. In addition, the weight reduction can improve the mechanical stiffness of the unit and reduce the mechanical load.

Metal halide perovskites are promising photovoltaic materials, but they still have some issues that need to be solved. Hysteresis is a phenomenon that strongly is correlated with ion migration; thus, a fast, easy, and low-temperature method for measuring ion migration is required. Through selective blocking, ion migration can be measured separately, apart from electron migration. In this study, ion migration in metal halide perovskites was measured using a vertical device. At different temperatures, ionic activation energies were obtained for a range of perovskite compositions such as MAPbI3, FAPbI3, CsPbI3, and MAPbBr3. By comparing the measured ionic activation energies with the theoretical values, we conclude that among other possibilities, I− is the migrating ion in MAPbI3, FAPbI3, CsPbI3, and Br− is the migrating in MAPbBr3.

Alkaline earth (AE) metals are irreplaceable ingredients in the synthesis of AE metal-based antiperovskite oxides, and it can be achieved by a chemical reduction of a stable AE metal compound. In this study, hydrogen and carbothermal reduction of BaO and BaCO3 were employed, and we here report an undesirable side reaction creating barium hydroxide (Ba(OH)2) as the product of the reaction with the small amount of water in ultra-high purity inert gas used in the reduction processes. Such side reaction pathways and products are hardly identifiable in a high-temperature reaction; yet, systematic investigations on phase evolutions using X-ray diffraction, IR spectroscopy, and thermogravimetric analysis enabled the detection of Ba(OH)2·xH2O. Unintentional creation of alkaline earth metal oxides in intermediate and subsequent hydration even under a negligible amount of H2O may lead to an unexpected loss of alkaline earth metal element and, consequently, its deficiency in a desired final product.

Nitrogen oxides (NOx; NO and NO2) are major air pollutants and can cause harmful effects on the human body. Electron Beam Flue Gas Treatment (EBFGT) is a technology that generates electrons with an energy of 0.5–1 MeV using electron accelerators and effectively processes exhaust gases. In this study, NOx was removed using an electron beam accelerator with spraying additives (NaOH and NH4OH). NO and NO2 were 100% and more than 94% removed, respectively, at an electron beam absorbed dose of 20 kGy and an additive concentration of 0.02 M (mol/L). In most cases, NOx was removed better with lower initial NOx concentrations and higher electron beam absorbed doses. As the irradiation strength (mA) of the electron beam increases, the probability of electron impact on the material accordingly rises, which may lead to increase removal efficiency. The results of the present study show that the continuous electron beam process using additives achieved more effective removal efficiency than either individual process (wet-scrubbing or EB irradiation only).

Diverse methods have been developed for the synthesis of active nanocatalysts involving various heterogeneous catalytic reactions. Thus far, numerous trial-and-error runs have been done to find the effective and practical ways. In the present work, the All-In-One (AIO) reactor system with a well-designed synthesis program, now in pilot stage, was first exploited as a reliable synthesis tool to find the optimum conditions for the production of Ni nanocatalysts. Using an activated charcoal support, active Ni nanoparticles of 7.8–11.8 nm (labeled A001–A007 in the program) were produced. These were achieved using a melt-impregnation process, which was controlled by variations in the applied gas (N2 and H2) and temperature (400 °C, 450 °C, and 500 °C) used as critical factors in the calcination step. Based on the optimization of the reaction sequence, each Ni nanocatalyst could be prepared within 5 h and 22 min. In particular, the optimum Ni nanocatalyst (A006) with the smallest particle size (7.8 nm), prepared under H2 flow at 400 °C, exhibits the highest catalytic activity (0.748 mmol4-NP·gcat-1·s-1) among the Ni catalysts for 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP). This activity is much higher than that of conventional supported Ni nanocatalysts (0.551 mmol4-NP·gcat-1·s-1) produced using the wetness method.

Chestnut fruit shell and ground coffee waste were evaluated as filler raw materials for plywood adhesive. A phenol-formaldehyde (PF) resin was formulated in the laboratory for plywood manufacture. Specification characteristics were determined on the PF resin, including nonvolatile solids, gel time, viscosity, etc. The laboratory synthesized PF resin was mixed with extender, filler and NaOH. Plywoods were uniformly made with the PF resin mixture and tested for tension shear strength after aging method, modulus of rupture (MOR) and thickness swell according to the procedures of the Korean Standard KS F 3101 and KS F 3114. All plywood made with each filler type showed good physical and mechanical strength properties. The performance test results indicated that the chestnut fruit shell and ground coffee waste would be suitable as filler for plywood adhesive.

Nafion, a perfluoro-sulfonic acid (PFSA)-based polymer, is a promising material that will help realize the commercialization of proton exchange membrane-based fuel cells (PEMFCs) and proton exchange membrane water electrolyzers (PEMWEs). However, Nafion also exhibits reduced mechanical and dimensional stability and increased hydrogen crossover under cell operating conditions in real operational settings, that is, in a hydrated state or in water at 60–80 °C. These factors may negatively affect cell efficiency and durability and thus must be addressed. To overcome these limitations, polyamide-coated Nafion composite membranes were developed for the first time via interfacial polymerization. 3,5-Diaminobenzoic acid (DABA), which contains carboxyl functional groups, was used as a monomer to add hydrophilicity to the membrane, and the coating layer thickness was controlled by adjusting the DABA content. A nanoscale polyamide (PA) layer was coated on the surface of Nafion-212 to fabricate a membrane, PA-c3-Nafion. PA-c3-Nafion was found to show ion conductivity 13.6% higher than that of a pristine Nafion-212 membrane at 80 °C, while providing improved mechanical performance and dimensional stability. In particular, at 95% RH, the hydrogen permeability of PA-c3-Nafion was 16.4% lower than that of Nafion-212 while, in a fully hydrated state, the hydrogen permeability of PA-c3-Nafion was 21.2% lower than that of Nafion-212. The LSV test results also showed that the degree of hydrogen crossover was significantly lower in PA-c3-Nafion than in Nafion-212.

Nano-hydroelectric technology utilizes hydraulic flow through electronically conducting nanomaterials to generate electricity in a simple, renewable, ubiquitous, and environmentally friendly manner. To date, several designs of nano-hydroelectric devices have been devised to maximize the electrokinetic interactions between water molecules and nanomaterials. However, the reported power generation of the state-of-the-art nano-hydroelectric generators is not sufficient for practical use, as tens of thousands of units were required to operate low-power electronics on a mW scale. Here, we utilize titanium carbide (Ti3C2Tx) MXene nanosheets, which have advantageous properties including metal-like conductivity and hydrophilicity, to facilitate the electrokinetic conversion of the transpiration–driven electrokinetic power generator (TEPG) with a remarkably improved energy generation efficiency compared to that of carbon-based TEPG. The Ti3C2Tx MXene-based TEPG delivered a high pseudo-streaming current of 120 μA by the fast capillary flow promoted by MXene sheets coated on cotton fabric. The strong cationic affinity of Ti3C2Tx enables the generator to achieve an output of 0.68 V and 2.73 mA when NaCl solution is applied. Moreover, incorporation of a conducting polymer (i.e., Ti3C2Tx/polyaniline composite) enhanced the ionic diffusivity while maintaining the electrical network of Ti3C2Tx. The optimized Ti3C2Tx/polyaniline composite TEPG generated a maximum voltage of 0.54 V, a current of 8.2 mA, and a specific power density of 30.9 mW cm−3, which was sufficient to successfully charge a commercial Li-ion battery as well as low-power electronics and devices with a volume of 6.72 cm3.

Oxygen reduction reaction, which proceeds at the cathode of a fuel cell, is primarily important as its rate determines the overall performance of the device. However, designing a single-phase material that meets multiple standards (e.g., high activity, stability, thermomechanical characteristics) at once to become an ideal cathode still remains a great challenge. In this regard, the use of multi-phase catalysts, especially those with nanoscale complex domains, may serve as a rational strategy. Here we present Ba0.5Sr0.5Co0.6Fe0.2Zr0.1Y0.1O3-δ (BSCFZY) as a superior biphasic nano-composite cathode, which self-assembles into two discrete cubic perovskites: Co-rich (Ba0.5Sr0.5Co0.7Fe0.2Zr0.07Y0.03O3-δ) and Zr-rich (Ba0.6Sr0.4Co0.3Fe0.2Zr0.4Y0.1O3-δ) phases. The former promotes the electrocatalytic activity while the latter supports the microstructural robustness; thus, the synergic ensemble of Co- and Zr-rich perovskite domains yields an area specific resistance of only ~0.013 Ω cm2 at 650oC, which is far superior to that anticipated from the component phases in isolation. The cooperative interaction found in multi-phase catalyst prepared via simple one-pot synthesis is not only attractive to the SOFCs but also for other kinds of energy conversion and storage devices, such as protonic ceramic electrochemical cells, electrolysers, and membrane chemical reformers.

The rapid development of non-fullerene acceptors (NFAs) with strong near-infrared absorption has led to remarkably enhanced short-circuit current density (Jsc) values in organic solar cells (OSCs). NFAs based on the benzotriazole (Bz) fused-ring π-core have great potential in delivering both high Jsc and decent open-circuit voltage values due to their strong intramolecular charge transfer with reasonably low energy loss. In this work, we have designed and synthesized a series of Bz-based NFAs, PN6SBO-4F, AN6SBO-4F and EHN6SEH-4F, via regiospecific N-alkyl engineering based on the high-performance NFA mBzS-4F that was reported previously. The molecular packing of mBzS-4F, AN6SBO-4F, and EHN6SEH-4F single crystals was analyzed using X-ray crystallography in order to provide a comprehensive understanding of the correlation between the molecular structure, the charge-transporting properties, and the solar cell performance. Compared with the typical honeycomb single-crystal structure of Y6 derivatives, these NFAs exhibit distinctly different molecular packing patterns. The strong interactions of terminal indanone groups in mBzS-4F and the J-aggregate-like packing in EHN6SEH-4F lead to the formation of ordered 3D networks in single-crystals with channels for efficient charge transport. Consequently, OSCs based on mBzS-4F and EHN6SEH-4F show efficient photon-to-current conversions, achieving the highest power conversion efficiency of 17.48% with a Jsc of 28.83 mA cm−2.

We investigated the effect of the thickness of superconducting layer on the competition between ferromagnetism and superconductivity. The epitaxial bilayer systems consisting of GdBa2Cu3O7-x (GdBCO) with varying thickness and La0.7Sr0.3MnO3 (LSMO) were grown on (001) SrTiO3 (STO) substrate. From the spectroscopic measurements, we observed an existence of a possible structural coupling between the GdBCO and the LSMO layers. The structural coupling is found to depend on the GdBCO thickness and to induce different types of strain on both layers, leading to the competition between the ferromagnetic and the superconducting orders. With respect to the flux pinning, an additional pinning contribution besides magnetic pinning induced by LSMO is emerged by the structural coupling, which is attributed to local atomic disorder. Controlling the thickness of GdBCO modifies the structural coupling and consequently, the degree of additional pinning contribution aroused by disorder on the CuO2 plane can be adjusted. An appropriate structure with a certain thickness amplifies the hybrid effect of magnetic pinning and additional pinning, resulting in an enhancement of the critical current density at high magnetic fields. Our findings suggest a possibility of controlling complex flux pinning through an optimization of structural coupling between the GdBCO and the LSMO layers.

We report a miniaturized, minimally invasive high-density neural recording interface that occupies only a 1.53 mm2 footprint for hybrid integration of a flexible probe and a 256-channel integrated circuit chip. To achieve such a compact form factor, we developed a custom flip-chip bonding technique using anisotropic conductive film and analog circuit-under-pad in a tiny pitch of 75 m. To enhance signal-to-noise ratios, we applied a reference-replica topology that can provide the matched input impedance for signal and reference paths in low-noise aimpliers (LNAs). The analog front-end (AFE) consists of LNAs, buffers, programmable gain amplifiers, 10b ADCs, a reference generator, a digital controller, and serial-peripheral interfaces (SPIs). The AFE consumes 51.92 W from 1.2 V and 1.8 V supplies in an area of 0.0161 mm2 per channel, implemented in a 180 nm CMOS process. The AFE shows > 60 dB mid-band CMRR, 6.32 Vrms input-referred noise from 0.5 Hz to 10 kHz, and 48 M input impedance at 1 kHz. The fabricated AFE chip was directly flip-chip bonded with a 256-channel flexible polyimide neural probe and assembled in a tiny head-stage PCB. Full functionalities of the fabricated 256-channel interface were validated in both in vitro and in vivo experiments, demonstrating the presented hybrid neural recording interface is suitable for various neuroscience studies in the quest of large scale, miniaturized recording systems.

Cement-based piezoresistive composites have attracted significant attention as smart construction materials for embedding self-sensing capability in concrete infrastructure. Although a number of studies have been conducted using multi-walled carbon nanotubes (MWCNTs) as a functional filler for self-sensing cement-based composites, studies addressing the influence of the internal moisture state on the electrical properties are relatively scant. In this study, we aim to experimentally investigate the effect of internal moisture state on the electrical resistivity of cement-based composites containing MWCNTs as an electrically conductive medium to raise a need for calibration of self-sensing data considering the internal moisture state. To this end, the moisture dependence of electrical resistivity in under-percolated cement-based composites was mainly evaluated, along with other material properties such as strength, shrinkage, and flowability. Results revealed that the electrical resistivity increased almost linearly as the internal relative humidity (IRH) decreased, and the increase was more pronounced below the percolation threshold. In addition, it was found that the strength gained by the microfiller effect of MWCNTs was significantly reduced particularly in under-percolated mixtures, leading to overall strength reductions. Furthermore, this study showed that the more the MWCNT was added, the smaller the flowability was obtained due to the increased viscosity of the mixture. The findings of this study are expected to provide pivotal information for accurate and reliable interpretations of self-sensing data generated by MWCNT-embedded cement-based composites.