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We designed novel thermally activated delayed fluorescence (TADF) materials by combining the electron donor 10,10-diphenyl-5,10-dihydrodibenzo[b,e][1,4]azasiline (DDA) with the electron acceptor triphenylphosphine oxide (PO) unit (mDDA-PO and o-mDDA-PO) and compared their characteristics with those of a reference material using 1,3-Bis(N-carbazolyl)benzene (mCP) as an electron donor (mCP-PO) for blue organic light-emitting diodes (OLEDs). Using density functional theory (DFT) and time-dependent DFT calculations, we obtained the electron distributions of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) as well as the energies of the lowest singlet (S1) and lowest triplet (T1) excited states. The calculated energy difference (ΔEST) between the S1 and T1 states of mDDA-PO (0.16 eV) and o-mDDA-PO (0.07 eV) were smaller than that of mCP-PO (0.48 eV). The results showed that o-mDDA-PO is a suitable blue OLED emitter because it has sufficiently small ΔEST values, which is favorable in a reverse-intersystem process crossing from the T1 state to S1 states, as well as an emission wavelength of 446.7 nm.

Many lattice-based cryptographic schemes are constructed based on hard problems on an algebraic structured lattice, such as the short integer solution (SIS) problems. These problems are called ring-SIS (R-SIS) and its generalized version, module-SIS (M-SIS). Generally, it has been considered that problems defined on the module lattice are more difficult than the problems defined on the ideal lattice. However, Koo, No, and Kim showed that R-SIS is more difficult than M-SIS under some norm constraints of R-SIS. However, this reduction has problems in that the rank of the module is limited to about half of the instances of R-SIS, and the comparison is not performed through the same modulus of R-SIS and M-SIS. In this paper, we propose the three reductions. First, we show that R-SIS is more difficult than M-SIS with the same modulus and ring dimension under some constraints of R-SIS. Also, we show that through the reduction from M-SIS to R-SIS with the same modulus, the rank of the module is extended as much as the number of instances of R-SIS from half of the number of instances of R-SIS compared to the previous work. Second, we show that R-SIS is more difficult than M-SIS under some constraints, which is tighter than the M-SIS in the previous work. Finally, we propose that M-SIS with the modulus prime $q^{k}$ is more difficult than M-SIS with the composite modulus $c$ , such that $c$ is divided by $q$ . Through the three reductions, we conclude that R-SIS with the modulus $q$ is more difficult than M-SIS with the composite modulus $c$ .

This study presents a tube-in-tube buckling-restrained brace (BRB) infilled with lightweight and rapid hardening polymer. The proposed BRB consists of a circular or square tube core encased with a tube of similar shape and polymer infill. The tube-in-tube arrangement minimizes the filler material volume and enables the use of rolled steel section as opposed to welded profiles commonly utilized when large BRB axial strength is required, although welded profiles suffer from low assembly accuracy resulting from welding deformation. The infilled polymer has a density of approximately half that of mortar and requires a curing time of 24 h, enabling weight and fabrication time reduction. The stability and inelastic deformation capability of the BRB were investigated through brace and subassembly tests of six circular and four-square full-scale specimens, followed by finite element analysis. The test results show that circular BRB designed with a Pcr/Py ratio of 1.46 exhibited a stable hysteresis up to 1.42% and 1.06% core strain in tension and compression, respectively. Circular and square specimens designed with Pcr/Py ratios ranging from 0.82 to 1.06 exhibited stable hysteresis before failing by global buckling at compressive core stains ranging from 0.86% to 1.09%. The slot weld detail adopted for welding core projection stiffener displayed a stable performance in circular BRB specimens, while it resulted in large plastic strain demand in square BRB specimens, leading to core fracture at tensile core strains ranging from 0.64% to 0.71%.

Novel blue thermally activated delayed fluorescence (TADF) emitters, D1-DPS and D2-DPS, were designed and synthesized. Diphenyl sulfone (DPS) group functioned as a common acceptor, and it combined with each of two different spiro-acridine groups, D1 and D2. The calculated energy differences (ΔEST) of the singlet and triplet excited states of D1-DPS (0.062 eV) and D2-DPS (0.128 eV) had sufficiently small ΔEST values, which is favorable in the thermally activated reverse intersystem crossing (RISC) process from the T1 state to the S1 state. A device doped 10 wt% of D2-DPS with ADN host material, obtained 5.05% of external quantum efficiency with deep-blue emission having CIExy coordinates of (0.152, 0.065). The results showed that these molecules are promising host-free TADF deep-blue emitters by inhibiting concentration quenching.

We designed novel thermally activated delayed fluorescence (TADF) materials with benzofuro[2,3-b]pyridine (BFP) as an electron acceptor and spiro[acridine-9,9'-fluorene] (D1) and spiro[acridine-9,9'-xanthene] (D2) as electron donors (BFP-D1 and BFP-D2) and compared their characteristics with those of a reference material using 9-phenylcarbazole (pCz) as an electron donor (BFP-pCz) for blue organic light-emitting diodes (OLEDs). Using density functional theory (DFT) and time-dependent DFT calculations, we obtained the electron distributions of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), and the energies of the lowest singlet (S1) and lowest triplet (T1) excited states. The calculated difference in energy (ΔEST) between the S1 and T1 states of BFP-D1 (0.06 eV) and BFP-D2 (0.07 eV) was smaller than that of BFP-pCz (0.89 eV). The results showed that BFP-D2 is a suitable blue OLED emitter because it has sufficiently small ΔEST values, which is favorable in a reverse-intersystem process crossing from the T1 state to S1 states, as well as an emission wavelength of 465.9 nm.

We designed novel thermally activated delayed fluorescence (TADF) host molecules for blue electrophosphorescence by combining the electron donor 1,3-Bis(N-carbazolyl)benzene (mCP) unit and the electron acceptor diphenylphosphine oxide-4-(triphenylsilyl) phenyl (TSPO1) unit in a single molecule based on density functional theory. We obtained the energies of the first singlet (S1) and the first triplet (T1) excited states of the TADF materials by performing density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations to the ground state using dependence on charge transfer amounts for the optimal Hartree-Fock percentage in the exchange-correlation of TD-DFT. Using DFT and TD-DFT calculations, the large separation between the HOMO and LUMO caused a small difference in energy (ΔEST) between the S1 and T1 states. The host molecules retained high triplet energy and showed great potential for use in blue phosphorescent organic light-emitting diodes. The results showed that these molecules are promising TADF host materials because they have a low barrier to hole and electron injection, balanced charge transport for both holes and electrons, and small ΔEST.

Novel thermally activated delayed fluorescence (TADF) emitters were designed with diphenylsulfone (DPS) as an electron acceptor and carbazole derivatives as electron donors and their electr...

In this study, the changes in the microstructural characteristics and mechanical properties of A356 alloys as a function of Mn content and cast thickness were evaluated using structural analysis and tensile tests. Five different A356+x%Mn alloys were prepared by casting in molds of different thicknesses followed by solid solution treatment at 813 K for 195 min and aging treatment at 423 K for 120 min. It was confirmed that the secondary dendrite arm spacing (SDAS) increased with increasing thickness of the cast sample, whilst, for a given thickness, the addition of small amounts of Mn resulted in a decrease of the SDAS. Mn contents of 0.05-0.15% resulted in ~7-9% improvements in the spheroid ratio of the primary Si particles compared to that of the commercial A356 alloy. Further, the spheroid ratio of the primary Si particles obtained in the thin cast samples were higher than that obtained in the thick cast samples. In particular, the addition of small amounts of Mn was also effective in suppressing the formation of the needle-like beta Al-Fe-Si intermetallic compound. The yield and tensile strengths of the thinner cast samples were higher than those of the thicker cast samples. Finally, Mn contents of 0.05-0.15% resulted in enhanced yield and tensile strengths, but Mn content ≥0.1% resulted in decreased elongation.

Cast iron is primarily used in buried piping to transport water in the fire protection system of nuclear power plants, ductile cast iron is generally used for domestic nuclear power plants. In general, the fluid used as fire-extinguishing water in such fire protection systems is tap water, and corrosion inhibitors are not currently added. In this study, the synergistic effect of an adsorption barrier (monoethanolamine) and oxidized film in an environment with a corrosion inhibitor (tungstate) is examined, and the corresponding passivation properties are presented. An immersion corrosion test and electrochemical test in tap water to which only tungstate was added showed suppression of corrosion compared to molybdate at the same concentration. The polarization resistance value of a passivation film in tap water mixed with monoethanolamine and tungstate showed better results than that of the molybdate control. A surface analysis in mixed addition tap water also demonstrated that oxygen ions were sufficiently distributed, including at some spheroidized graphite sites, when tungstate was added compared to molybdate. In addition, the amount of tungsten ions adsorbed on the surface was larger than that of molybdenum ions, and it was confirmed that tungsten ions were evenly distributed over the entire surface.

Conventional slit dampers are widely used for the purpose of seismic retrofitting, however, the structure of these dampers is susceptible to fractures, due to stress concentration at the ends of the strips in the event of large earthquakes. To address this issue, a novel radius-cut coke-shaped strip damper featuring improved ductility is proposed herein. This damper was developed based on the moment distribution over the strip when both its ends were constrained. The height-to-width ratio of the strip was increased to induce bending rather than shear deformation, and the reduced beam section method was employed. A radius-cut section was used to intentionally focus the stress to induce the plastic hinge. This reduced the fracture fragility of the specimen, resulting in an increased inelastic deformation capacity. Cyclic loading tests were conducted to verify damping performance against earthquakes. Experiments and finite element analyses proved that the coke-shaped damper exhibits improved ductility. The final fracture occurred in the radius-cut section after sufficient energy dissipation during cyclic loading. The results also indicated further improvements in strength due to the membrane effect under cyclic loading, caused by the tensile resistance of the strip due to its constrained ends.

We designed novel thermally activated delayed fluorescence (TADF) materials by combining the electron donors spiro[acridine-9,9′-fluorene] (D1) and 9,9-diphenyl acridan (PAC) with the electron acceptor phenoxaphosphine (OPO) unit (2D1-OPO and 2PAC-OPO) and used those property to compare it with that of the reference material using dimethylacridan (Ac) as an electron donor (Ac-OPO) for blue organic light-emitting diodes (OLEDs). To calculate electron distribution of highest occupied molecular orbitals (HOMO), lowest occupied molecular orbital (LUMO), lowest singlet (S1) energy and lowest triplet (T1) excitation states, density functional theory (DFT) and time-dependent DFT calculation have been used. The calculated energy difference (ΔEST) between the S1 and T1 states of 2D1-OPO (0.125 eV) and 2PAC-OPO (0.153 eV) were as small as that of Ac-OPO (0.127 eV). The results showed that 2D1-OPO is a good candidate for blue OLED emitter because it has an emission wavelength of 441.0 nm as well as a sufficiently small ΔEST value and large oscillator intensity value.

Novel thermally activated delayed fluorescence (TADF) host materials for blue electrophosphores-cence were designed by combining the electron acceptor dibenzothiophene (DBT) unit and the electron donor acridine derivatives into a single molecular unit by density functional theory (DFT). Depending on the optimal charge transfer, DFT and time-dependent DFT (TD-DFT) calculations for the ground state were performed to obtain the energy of the singlet (S1) and triplet (T1) excited states of the TADF material for Hartree-Fock percentage of TD-DFT. The sufficiently large separation between the HOMO and LUMO resulted in a small difference in energy (ΔEST) between the S1 and T1 states using DFT and TD-DFT calculations. The host molecules retained high triplet energy and showed great potential for use in blue organic light-emitting diodes (OLED). The results showed that these molecules are a good TADF host materials because they have a low barrier to hole and electron injection with a balanced charge transporting property for both holes and electrons, and a small ΔEST.

We designed a novel thermally activated delayed fluorescence (TADF) host molecules for blue elec-trophosphorescence by combining the electron acceptor benzimidazole (BI) unit and the electron donor acridine derivatives into a single molecular unit based on density functional theory (DFT). We obtained the energies of the first singlet (S1) and the first triplet (T1) excited states of the TADF materials by performing DFT and time-dependent DFT (TD-DFT) calculations on the ground state using dependence on charge transfer amounts for the optimal Hartree–Fock percentage in the exchange-correlation of TD-DFT. The DFT and TD-DFT calculations showed that the large separation between the highest occupied molecular orbital and the lowest unoccupied molecular orbital caused a small difference in energy (ΔEST) between the S1 and T1 states. The host molecules retained a high triplet energy and demonstrated a great potential for use in blue phosphorescent organic light-emitting diodes. The results showed that these molecules are promising host materials for TADF OLEDs because they have a low barrier to hole and electron injection, a balanced charge transport for both holes and electrons, and a small ΔEST.

An asymmetric A-π-D-π-A’ organic dye (dye1) combining a red D − π−A dye (D35) and a blue D − π−A’ dye (DB) on each side of a triphenylamine (TPA) was designed, and a theoretical study was c...

A novel carbazole-based organic dye with heteroleptic dual electron acceptors (cyanoacrylic acid and thieno[3,4-b]pyrazine acid) on each side of a quinoxaline was designed, and its electronic and optical properties were investigated theoretically for dye-sensitized solar cells (DSSCs). To gain insight into the factors responsible for photovoltaic efficiency, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations of these dyes were performed. The absorption spectrum of the dyes showed different forms because of the different energy levels of the molecular orbital (MO) of each dye and the intramolecular energy transfer (EnT). Considering the overall properties, the asymmetric organic dye containing the heteroleptic dual acceptors showed a competitive conversion efficiency, greater red-shift, broader absorption spectra, and higher molar extinction coefficient compared to a single acceptor in the conversion efficiency of the DSSCs. These results indicate that heteroleptic dual acceptors produces good photovoltaic properties for DSSC.

In this study, phenoxazine (PXZ)-based dye sensitizers with triphenylamine (TPA) as a dual-electron donor and thiophen and benzothiadiazole (BTD) or 4,7-diethynylbenzo[c][1,2,5]thiadiazole (DEBT) as an electron acceptor (dye1, dye2, and dye3) were designed and investigated. dye3 can significantly stabilize the lowest unoccupied molecular orbital (LUMO) energy level of an organic dye. We used density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations to better understand the factors responsible for the photovoltaic performance. The absorption spectrum of the dyes showed different forms because of the different energy levels of the molecular orbital (MO) of each dye and the intramolecular energy transfer (EnT). Among the three dyes, dye3 showed greater red-shift, broader absorption spectra, and higher molar extinction coefficient. These results indicate that adding a withdrawing unit and π-conjugation to a dye can result in good photovoltaic properties for dye-sensitized solar cells (DSSCs).

Novel thermally activated delayed fluorescence (TADF) materials with benzofuro[2,3-b]pyridine (BFPd) as an electron acceptor and carbazole derivatives [carbazole (Cz), 1,3,6,8-tetramethyl-9H-carbazole (tmCz), and 9'H-9,3':6',9''-tercarbazole (terCz)] as electron donors are designed, and their electronic and optical properties are investigated theoretically for a deep blue organic light-emitting diode (OLED). We obtain the energies of the first singlet (S1) and first triplet (T1) excited states of TADF materials by performing density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations on the ground state by using the dependence on charge transfer amounts for the optimal Hartree-Fock percentage in the exchange-correlation of TD-DFT. We show that terCz-BFPd would be a suitable blue OLED emitter because it has sufficiently small ΔEST value (0.048 eV), which is favorable for a reverse intersystem crossing process from the T1 to S1 states and an emission wavelength of 432.8 nm with sufficiently large oscillator strength (F) value.

Visible-near-infrared (VIS-NIR) spectroscopy is a fast and non-destructive method for analyzing materials. However, most commercial VIS-NIR spectrometers are inappropriate for use in various locations such as in homes or offices because of their size and cost. In this paper, we classified eight food powders using a portable VIS-NIR spectrometer with a wavelength range of 450–1,000 nm. We developed three machine learning models using the spectral data for the eight food powders. The proposed three machine learning models (random forest, k-nearest neighbors, and support vector machine) achieved an accuracy of 87%, 98%, and 100%, respectively. Our experimental results showed that the support vector machine model is the most suitable for classifying non-linear spectral data. We demonstrated the potential of material analysis using a portable VIS-NIR spectrometer.

Novel thermally activated delayed fluorescence (TADF) materials (PCD-TRZ and PCCD-TRZ) with 9,9-dimethyl-9,10-dihydroacridine derivatives (PCD and PCCD) as electron donors and a triphenyl-triazine ...

We investigated the effect of heteroleptic dual electron acceptor as a photosensitizer for the dye-sensitized solar cells (DSSCs). Novel tribranched organic dyes were designed with heteroleptic dua...

During the synthesis of Bi2Ge3O9 ceramics using Bi2O3 + 3GeO2 powders, the Bi4Ge3O12 phase was formed at low temperature (≤800 °C). Bi4Ge3O12 preferentially adopted GeO2-excess phase, and this phase was consistently present in the sintered Bi2Ge3O9 ceramic as a secondary phase. Therefore, Bi4Ge3O12 powder was first calcined and subsequently reacted with GeO2 powder to obtain the pure Bi2Ge3O9 ceramic through the following reaction: 1/2Bi4Ge3O12 + 3/2GeO2 → Bi2Ge3O9. Formation of the Bi2Ge3O9 phase was initiated at temperature of 850 °C. The pure Bi2Ge3O9 ceramic sintered at 875 °C for 8 h had a dense microstructure with an average grain size of 2.7 μm. Furthermore, the pure Bi2Ge3O9 ceramic exhibited promising microwave dielectric properties for the advanced ceramic substrate: er = 9.7, Q × f = 48,573 GHz and τf = −29.5 ppm/°C.

Dense Bi 4 Ge 3 O 12 ceramics sintered at 850 °C had a relative permittivity ( e r ) of 15.7, temperature coefficient of resonant frequency ( τ f ) of −24.2 ppm/°C, and quality factor ( Q × f ) of 28,361 GHz. However, because of the existence of Bi 12 GeO 20 as a secondary phase, the microwave dielectric properties of Bi 4 Ge 3 O 12 would be degraded. Therefore, to avoid the formation of the Bi 12 GeO 20 secondary phase, Bi 2 O 3 -deficient Bi 4- x Ge 3 O 12-1.5 x ceramics with 0.1≤ x ≤0.6 were sintered at 850 °C. A single phase of Bi 3.6 Ge 3 O 11.4 ( x =0.4) ceramic sintered at 850 °C for 5 h without any secondary phase exhibited suitable microwave dielectric properties for a ceramic substrate: e r =14.9, τ f =−9.5 ppm/°C, and Q × f =53,277 GHz.

To suppress stress corrosion-cracking, compressive residual stresses, such as shot peening, laser peening, water jet peening, ultrasonic peening, and ultrasonic nanocrystal surface modification (UNSM) are utilized. However, among the numerous techniques, there is little research about the corrosion effect of detailed conditions, such as static load or amplitude in UNSM. A study on UNSM among various techniques of adding compressive residual stress to Alloy 600 was conducted. The focus of this study was on the effect of the static load in UNSM on the corrosion properties of Alloy 600. Microstructure analysis was conducted using an optical microscope (OM), a scanning electron microscope (SEM), and electron backscattering diffraction (EBSD), while compressive residual stress was measured using a nano-indentation technique. A cyclic polarization test and the AC (Alternating Current)-impedance measurement were both used to analyze the corrosion properties. An increase in static load under critical static load enhanced the grain boundary diffusion, consequently strengthened the passive film, and facilitated the surface diffusion, thereby improving the passivation of Alloy 600. However, higher static loads over the critical value can lead to an increase in the friction between the striking tip and the surface, thereby creating an overlapped wave, which reduces the corrosion properties.

We designed novel thermally activated delayed fluorescence (TADF) host molecules for blue electrophosphorescence by combining electron donor acridine derivatives and the electron acceptor 3,4,5-triphenyl-1,2,4-triazole (TPT) unit into a single molecule based on density functional theory (DFT). We obtain the energies of the first singlet (S1) and first triplet (T1) excited states of TADF materials by performing DFT and time-dependent DFT (TD-DFT) calculations on the ground state using dependence on charge transfer amounts for the optimal Hartree-Fock percentage in the exchange-correlation of TD-DFT. The host molecules retained high triplet energy and showed great potential for use in blue phosphorescent organic light-emitting diodes. The results showed that these molecules are promising TADF host materials because they have a low barrier to hole and electron injection, a balanced charge transport for both holes and electrons, and a small energy difference (ΔEST) between the S1 and T1 states.

Novel thermally activated delayed fluorescence (TADF) materials with 9,9-dimethyl-9H-thioxanthene 10,10-dioxide (SB) as an electron acceptor and andspiro[acridine-9,9'-fluorene] (D1) and spiro[acridine-9,9'-xanthene] (D2) as electron donors (2D1-SB and 2D2-SB) and their characteristics were compared with those of a reference material using 9,9-dimethylacridin (DMAC) as an electron donor (2DMAC-SB) for blue organic light-emitting diodes (OLEDs). We obtain the energies of the first singlet (S1) and first triplet (T1) excited states of TADF materials by performing density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations on the ground state using the dependence on charge transfer amounts for the optimal Hartree-Fock percentage in the exchange-correlation of TD-DFT. We show that 2D2-SB would be a suitable blue OLED emitter because it has sufficiently small value (0.064 eV) of energy difference (ΔEST) between the S1 and T1 states, which is favorable for a reverse inter system crossing process from the T1 to S1 states and an emission wavelength of 439.5 nm with sufficiently large oscillator strength (F) value.

Biologic augmentation for rotator cuff repair is a challenging treatment in patients with chronic large, massive, and irreparable rotator cuff injuries. Particularly, the use of an extracellular matrix (ECM) patch such as dermal tissue offered improved biomechanical properties in previous studies. Cytokines induce cell chemotaxis, proliferation, matrix synthesis, and cell differentiation. Moreover, osteoinductive growth factors such as bone morphogenetic protein-2 (BMP-2) affect the formation of new bone and fibrocartilage in lesions. However, the effects of using a dermal patch in combination with BMP-2 have not been evaluated to date, although many researchers have recognized the importance thereof. In this study, rhBMP-2-coated dermal patch (1 cm × 2 cm) isolated from human cadaveric donor was inserted in a rabbit model of chronic rotator cuff injury for in vivo evaluation. Bone mineral density and biomechanical strength were tested and histological and histomorphometric analyses were performed. The results showed that insertion of an rhBMP-2-coated acellular dermal patch not only significantly ameliorated new bone formation, it also improved biomechanical properties such as ultimate tensile strength. Thus, the use of this combination may improve the chronic rotator cuff injury-healing rate and clinical outcomes after rotator cuff repair. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1840-1846, 2017.

Many industries need the universal standard or technique to obtain the identical CCT regardless of specimen geometries. This study aimed to determine an appropriate applied torque to the cylindrical specimen defining the apparatus and the procedure to measure the temperature of initiating crevice corrosion in tubular shape products such as pipes, tubes and round rods etc; the test method also proved applicable to the plate type specimen. A series of experiments for CCT measurements with the plate type and cylindrical stainless steel specimens of various diameters with different microstructures (austenitic and duplex) and PRENs were conducted to determine the relationship among geometries on CCT. Thus, the apparatus that could measure the CCT of stainless steels with both plate and cylindrical geometries was newly designed. The use of the apparatus facilitated the same CCT value for both geometries only if the specimens were made of the same alloy. The applied torque can be calculated for various diameters of the cylindrical specimens using the following relation; Applied torque, Nm = -0.0012D 2 + 0.019D + 2.4463 (D; the diameter of cylindrical specimen, mm). However, upwards of 35 mm diameter cylindrical specimens require 1.58Nm, which is the same torque for the plate type specimen; in addition, this test method cannot be used for cylindrical specimens of less than 15 mm diameter.

Bi12GeO20 ceramics sintered at 800°C had dense microstructures, with an average grain size of 1.5 μm, a relative permittivity (er) of 36.97, temperature coefficient of resonance frequency (τf) of −32.803 ppm/°C, and quality factor (Q × f) of 3137 GHz. The Bi12-xGeO20-1.5x ceramics were well sintered at both 800°C and 825°C, with average grain sizes exceeding 100 μm for x ≤ 1.0. However, the grain size decreased for x > 1.0 because of the Bi4Ge3O12 secondary phase that formed at the grain boundaries. Bi12-xGeO20-1.5x (x ≤ 1.0) ceramics showed increased Q × f values of >10 000 GHz, although the er and τf values were similar to those of Bi12GeO20 ceramics. The increased Q × f value resulted from the increased grain size. In particular, the Bi11.6GeO19.4 ceramic sintered at 825°C for 3 h showed good microwave dielectric properties of er = 37.81, τf = −33.839 ppm/°C, and Q × f = 14 455 GHz.

Generally, indirect assessment of external corrosion of pipe has been undertaken as a 2 step process using a close interval potential survey (CIPS) performed to determine the level of cathodic polarization and a direct current voltage gradient (DCVG) survey to determine the location of coating defects on the pipes buried in the soil. Usually, two techniques are used separately, but there are several advantages to undertaking a combined CIPS and DCVG survey. However, since detection conditions depend upon the experience skill of the experts, the reliability to detect the coating flaw on pipes buried in the soil was low level. This work focused on the deduction of detection voltage to get 100% reliabilty of coating flaw detection on pipes buried in the soil. Test bed with 3 layered pipelines was constructed, and cathodic protection system was real-time monitored. The material of buried pipe was one kind of ‘polyken coated steel pipe’. The burial depths of pipes were from 1 to 3 meters and coating flaws on the pipes were intentionally formed. The effect of applied voltage on the detection reliability of coating flaw on buried pipe in soil was elucidated. The applied voltage to detect the coating flaws is dependent upon the amount of buried pipes and soil condition etc. The detection potential to get 100 % detection reliability can be calculated using the newly proposed equation. (This work was supported by the Nuclear Power Core Technology Development Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20171520000350))

We have designed and characterized an injectable, electrostatically bonded, in situ–forming hydrogel system consisting of a cationic polyelectrolyte [(methoxy)polyethylene glycol-b-(poly(e-caprolactone)-ran-poly(L-lactic acid)] (MP) copolymer derivatized with an amine group (MP-NH2) and anionic BMP2. To the best of our knowledge, there have been hardly any studies that have investigated electrostatically bonded, in situ–forming hydrogel systems consisting of MP-NH2 and BMP2, with respect to how they promote in vivo osteogenic differentiation of human turbinate mesenchymal stem cells (hTMSCs). Injectable formulations almost immediately formed an electrostatically loaded hydrogel depot containing BMP2, upon injection into mice. The hydrogel features and stability of BMP2 inside the hydrogel were significantly affected by the electrostatic attraction between BMP2 and MP-NH2. Additionally, the time BMP2 spent inside the hydrogel depot was prolonged in vivo, as evidenced by in vivo near-infrared fluorescence imaging. Biocompatibility was demonstrated by the fact that hTMSCs survived in vivo, even after 8 weeks and even though relatively few macrophages were in the hydrogel depot. The osteogenic capacity of the electrostatically loaded hydrogel implants containing BMP2 was higher than that of a hydrogel that was simply loaded with BMP2, as evidenced by Alizarin Red S, von Kossa, and hematoxylin and eosin staining as well as osteonectin, osteopontin, osteocalcin, and type 1α collagen mRNA expression. The results confirmed that our injectable, in situ–forming hydrogel system, electrostatically loaded with BMP2, can enhance in vivo osteogenic differentiation of hTMSCs.

Novel thermally activated delayed fluorescence (TADF) materials with pyridine (Pd), pyrimidine (Pm), and triazine (Trz) as electron acceptors and carbazole (Cz) as an electron donor (TmCzPd, TmCzPm, and TmCzTrz) were designed, and the effect of the number of nitrogen (N) atoms with acceptor units was investigated by comparing their electronic and optical properties for blue organic light-emitting diodes (OLEDs). Using density functional theory (DFT) and time-dependent DFT calculations, we obtained the electron distributions of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), and the energies of the lowest singlet (S1)and lowest triplet (T1) excited states. The calculated energy difference (ΔEST) between the S1 and T1 states of TmCzPm (0.200 eV) and TmCzTrz (0.186 eV) were smaller than that of TmCzPd (0.395 eV). We show that TmCzPm would be a suitable blue OLED emitter because it has sufficiently small ΔEST values, which is favorable for a reverse intersystem crossing process from the T1 to S1 states, and an emission wavelength of 473.1 nm with sufficiently large oscillator strength for fluorescence.

A novel quinoxaline-based organic dye with heteroleptic dual electron donors (phenoxazine and carbazole) on each side of a quinoxaline was designed, and its electronic and optical properties were investigated theoretically for applications to dye-sensitized solar cells (DSSCs). To understand the factors influencing the photovoltaic efficiency, density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations of these dyes were performed. The absorption spectrum of the dyes showed different forms because of the different energy levels of the molecular orbital (MO) of each dye and the intramolecular charge-transfer (ICT) characteristics. The asymmetric organic dye with the heteroleptic dual donor showed competitive conversion efficiency, greater red-shift, broader absorption spectra, and higher molar extinction coefficient compared to dyes with homoleptic dual donors. These results indicate that adding a withdrawing unit and heteroleptic donor produces good photovoltaic properties for DSSCs.

Novel thermally activated delayed fluorescence (TADF) materials including 10H-phenoxaborin (PXB) as an electron acceptor and carbazole derivatives [carbazole (Cz), 1-methyl-carbazole (1-m-Cz), and 3,6-bis(3,6-diphenylcarbazolyl)carbazole (BDPCC)] as electron donors (Cz-PXB, 1-m-Cz-PXB, and BDPCC-PXB) were designed and investigated theoretically for deep blue organic light-emitting diode (OLED). Using density functional theory (DFT) and time-dependent DFT calculations, we obtained the electron distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and the energy of the lowest singlet (S1) and the lowest triplet (T1) excited states. Values for the calculated energy difference between the S1 state and the T1 state (ΔEST) of 1-m-Cz-PXB (0.158 eV) and BDPCC-PXB (0.058 eV) were smaller than for Cz-PXB (0.265 eV). Both materials had sufficiently small ΔEST values, which is favorable for a reverse intersystem crossing process (RISC) from the T1 to the S1 states. 1-m-Cz-PXB (0.1067) and BDPCC-PXB (0.0857) also have larger oscillator strengths (F) than reference material DMAC-PXB (0.0001). Our results showed that 1-m-Cz-PXB and BDPCC-PXB would have highly efficient TADF properties in terms of a small-enough energy difference (ΔEST) between the S1 state and the T1 state and a large F for the OLED.

In this study, the influence of the processing parameters, such as the synthesis temperature and the lithium sources on the structure, particle size, morphology and ionic conductivity of Li1+xTi2−xAlx(PO4)3 (LTAPO) was investigated. LiNO3, LiCl, and Li acetate were employed as lithium sources for investigating the effects of Li sources on the properties of the solid electrolyte. The morphologies and the particle size distribution of the prepared LTAPO samples were analyzed by using scanning electron microscopy (SEM) and a laser particle size analyzer. Their crystallinities were measured by means of X-ray diffraction (XRD). An increase in the synthesis temperature caused a pronounced growth in the particle size without any impurities, especially at temperatures above 700 °C. In addition, LiCl lithium sources showed the highest particles size. The effect of the processing parameters on the ionic conductivity of the prepared LTAPO was investigated by using electrochemical impedance spectroscopy (EIS). The ionic conductivities of the LTAPO prepared by using an optimized synthesis temperature with different lithium sources were 8.36 × 10−4, 5.73 × 10−4, and 7.18 × 10−4 S/cm for C-LTAPO, A-LTAPO, and N-LTAPO, respectively. The properties of the ceramic solid electrolyte were shown to be affected by the choice of the synthesis temperature and the Li source material.

This study presents a very short pyramidal horn antenna for monitoring the radiation characteristics of mobile base-station (BS) antennas operating in the long-term evolution (LTE)/cellular band. The proposed short pyramidal horn is integrated with metal strips/rods to overcome deficiencies of the shortened horn, especially in its front-to-back (F/B) ratio. The proposed short horn antenna improves the average F/B ratio by at least 8 dB in the frequency range from 690-960 MHz by controlling the edge diffraction. The total length of the antenna, including a waveguide flange, is only approximately 0.6 λ at 800 MHz. The proposed antenna also retains good characteristics such as a monotonically increasing gain, wide bandwidth, and a good purity of polarisation. The proposed antenna can replace the dipole antenna as a reference gain antenna for both indoor and outdoor measurement systems below the L-band.