Search

The development of highly stable and efficient oxide-based red phosphors is urgently required for next-generation lighting devices. Herein, we report the micro/crystal structures and luminescent properties of single-phase Eu2(WO4)3 and Eu3+-doped WO3-Eu2(WO4)3 composite phosphors prepared by a one-step conventional solid-state reaction method in air atmosphere. As increasing Eu contents in the mixtures of WO3 and Eu2O3, the intensities of the X-ray diffraction peaks of Eu2(WO4)3 increased while that of WO3 decreased. The photoluminescence intensity of the synthesized phosphors increased with increase in the Eu content when calcined at 900 °C, while it degraded at a higher temperature. Red-emitting single-phase Eu2(WO4)3 powders were successfully obtained when the WO3 and Eu2O3 powders were calcined in the ratio of 3:1. The intensity of the red emission spectra of the Eu2(WO4)3 phosphor was higher than those of the 6, 12, and 24 at.% Eu-added WO3 composites at excitation wavelengths of 394 and 465 nm. On the other hand, the intensity of emission from the single-phase phosphor was lower than that of the Eu-doped WO3-Eu2(WO4)3 composites under excitation of UV light at 254 nm. Thus, we propose two prospective phosphors for application as red phosphors at various wavelengths.

Ribosomal protein S3 (rpS3), a member of 40S small ribosomal subunit, is a multifunctional protein with various extra-ribosomal functions including DNA repair endonuclease activity and is secreted from cancer cells. Therefore, antibodies with high specificity against rpS3 protein could be useful cancer biomarkers. In this study, polyclonal antibody (pAb) and monoclonal antibodies (mAbs) were raised against rpS3 protein and epitope mapping was performed for each antibody; the amino acid residues of rpS3 were scanned from amino acid 185 to 243 through peptide scanning to reveal the epitopes of each mAb. Results showed that pAb R2 has an epitope from amino acid 203 to 230, mAb M7 has an epitope from amino acid 213 to 221, and mAb M8 has an epitope from amino acid 197 to 219. Taken together, novel mAbs and pAb against rpS3 were raised and mapped against rpS3 with different specific epitopes.

DNA double-strand breaks (DSBs) are one of the most serious types of DNA damage. However, multiple repair pathways are present in cells to ensure rapid and appropriate repair of DSBs. Pathway selection depends on several factors including cell type, cell cycle phase, and damage severity. Ribosomal protein S3 (rpS3), a component of the 40S small ribosomal subunit, is a multi-functional protein primarily involved in protein synthesis. rpS3 is also involved in the mediation of various extra-ribosomal pathways, including DNA damage processing and the stress response. Here, we report that rpS3 is a novel negative regulator of non-homologous end joining (NHEJ)-mediated repair of DSBs. We found that rpS3 interacts with the Ku heterodimers of the DNA-dependent protein kinase (DNA-PK) complex and slows down NHEJ ligation reactions, ultimately triggering p53-dependent cell death following treatment with high-dose ionizing radiation. After DSB formation, DNA-PK phosphorylates rpS3, which consequently reduces the binding of rpS3 to the Ku complex. We hypothesized that rpS3 may play a role in DSB repair by repressing NHEJ, while inducing other repair pathways, and by initiating DSB-induced cell death in response to severe DNA damage.

Translation is a costly, but inevitable, cell maintenance process. To reduce unnecessary ATP consumption in cells, a fine-tuning mechanism is needed for both ribosome biogenesis and translation. Previous studies have suggested that the ribosome functions as a hub for many cellular signals such as ribotoxic stress response, mammalian target of rapamycin (mTOR), and ribosomal S6 kinase (RSK) signaling. Therefore, we investigated the relationship between ribosomes and mitogen-activated protein kinase (MAPK) activation under ribotoxic stress conditions and found that the activation of c-Jun N-terminal kinases (JNKs) was suppressed by ribosomal protein knockdown but that of p38 was not. In addition, we found that JNK activation is driven by the association of inactive JNK in the 80S monosomes rather than the polysomes. Overall, these data suggest that the activation of JNKs by ribotoxic stress is attributable to 80S monosomes. These 80S monosomes are active ribosomes that are ready to initiate protein translation, rather than polysomes that are already acting ribosomes involved in translation elongation. [BMB Reports 2019; 52(8): 502-507]

The experimental observation of the transformation of nanosized SAC (Sn3.0Ag0.5Cu) into bulk-sized SAC during the melting process involving a large melting-point depression, using DSC (differential scanning calorimetry) and the reflow test is documented. They manufactured the nanosized SAC in dielectric benzyl alcohol using the modified direct-current arc method. The nanoparticles were spherical in shape with a size distribution of 5–10 nm. Using DSC, the endothermic peaks were continuously measured twice without changing the nanosized SAC. During the initial measurement, they observed peaks at 133, 162 and 217°C. However, in the second cycle, they observed only one peak at 217°C, which indicates the SAC nanoparticles have been completely melted and changed into bulk-sized SAC in the first cycle. They first conducted a reflow test of the SAC nanoparticles suspended in benzyl alcohol including flux on a printed circuit board and a hot plate which are 170°C. It was observed that SAC nanoparticles were transformed into bulk-sized SAC during the melting process at 170°C in less than 3 min. After the melting process, they also observed the formation of thin-layer geometry of SAC with 100 nm and intermetallic Cu6Sn5 between the SAC thin layer and a copper plate on PCB.

To analyze the trends in molecular interaction between bovine α-LA (BLA) and oleic acid, we investigated the effects of pH and protein conformation on oleate binding to BLA and compared the order-of-magnitude differences in binding behavior. Both isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) were used. For the ITC experiments, a solution of holo- or apo-BLA was titrated with sodium oleate at pH 4.0 and 10.0 to look for protein surface charge effects. In the SPR experiments, BLA was immobilized on the chip surface and sodium oleate solutions at various pHs (4.0, 5.5, 7.0, 8.5 and 10.0) were injected. Binding stoichiometry of ca. 5.2 molecules of oleate per unit molecule of BLA was observed. apo-BLA at a lower pH (lower than the pI of α-LA) yielded stronger binding avidity and affinity, which indicated that electrostatic interactions between the basic residues and the negatively charged carboxyl groups may play a major role in the complexation, in addition to hydrophobic interactions. The complexes formed at pH 4.0 and 5.5 were relatively unstable and rapidly dissociated when exposed to pH 7.0. In summary, we propose that the complexation can be regarded as a very weak (or, transient) and multivalent binding, requiring both electrostatic and hydrophobic interactions, probably in series and also in a dynamic equilibrium.

We developed a rapid quantification method of Pu, Am, and Cm in low- and intermediate-level radioactive waste using TRU resin, alpha spectrometry, and thermal ionization mass spectrometry for radioactive waste disposal. In particular, we focused on the optimization of sample preparation methods for alpha spectrometry and mass spectrometry to reduce the analysis time. The optimized method used Am and Pu stripping solutions for micro-coprecipitation and showed good recovery and alpha spectrum resolution for alpha counting. In addition, appropriate selection of Pu elution solution decreased the sample preparation time for thermal ionization mass spectrometry measurements.

The resistivity, breakdown strength, and formation of space charges are very important factors for insulation design of HVDC cable. It is known that a nano-sized metal-oxide inorganic filler reduces the formation of space charges in the polymer nanocomposite. Electrical conduction of cross-linked polyethylene(XLPE) nanocomposite insulating material is investigated in this paper. The conduction currents of two kinds of XLPE nanocomposites and XLPE without nano-filler were measured at temperature of 303 ~ 363 K under the applied electric fields of 10 ~ 50 kV/mm. The current of the nanocomposite specimen is smaller than that of XLPE specimen without nano-filler. The conduction mechanism may be explained in terms of Schottky emission and multi-core model.

Ion transport properties of block copolymers with lamellar morphologies, which contain ionic liquids (ILs), were investigated. By varying the type of anion in the ILs, dissimilar substructures of lamellar microdomains were identified using different elastic scattering techniques. By decoupling the segmental motion of polymer chains from conductivity, a wide range of normalized conductivities from 0.03 to 0.6 (theoretical value of 1) were determined, depending on the type of IL. The highest conductivity was achieved when ILs were confined within ionic domains with a sharp interface, owing to the creation of less tortuous ion conduction pathways. In contrast, a high degree of intermixing of ionic and nonionic domains at the interface, because of IL incorporation, revealed a reduction by 1 order of magnitude in the conductivity. This work presents fascinating experimental insights into confinement- and interface-driven modulation of ion transport properties for polymer electrolytes and presents the future pr...

The initial growth of Co thin films during plasma-enhanced atomic layer deposition (PE-ALD) is investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), and synchrotron radiation X-ray reflectivity (SR-XRR). For the PE-ALD of Co, CoCp2 and NH3 plasma were used as precursor and reactant, respectively. From XRR simulation, the growth rate at the initial stage of growth did not linearly increase with growth cycles, showing deviation from ideal ALD growth. The low density of PE-ALD-produced Co film up to 100 cycles is observed from XRR and confirmed by AFM and SEM results. The growth behavior of Co is explained by island growth under substrate-inhibited growth mode.

The structural properties of normal-type spinel ZnCr 2 Se 4 have been studied as a function of temperature by means of X-ray diffraction using synchrotron radiation. It is found that a structural phase transition from cubic to orthorhombic symmetry occurs at 22.5 K (T c ). It is also found that, below T c , Se ions are cooperatively displaced in a pseudo-tetragonal (001) plane. Since the Cr 3+ ion has no orbital angular momentum, a CrSe 6 octahedron is not distorted by a crystal field produced by surrounding Se 2- anions. It is interpreted that the pseudo-tetragonal displacements of Se ions are induced by magnetostriction among Cr 3+ ions in CrSe 2 chains, in which Cr ions share two Se 2- with each other along (110).

The structural phase transitions of the layer compound BaMnF4 were studied by high-resolution X-ray diffraction using synchrotron radiation. The intensities and profiles of two kinds of superlattice reflections having incommensurate reduced wave vectors q 1= (∼ ± 1/5,0,0) p and q 2 =(∼ ± 2/5,1/2,1/2)p, respectively, were measured as a function of temperature from 25 K to 280 K. These temperature dependencies show that incommensurate structural phase transitions of second order occur at 234 K and 244 K. These structural phase transitions are interpreted as successive condensations of a folding-screen-like incommensurate plane-distortion mode and a commensurate anti-ferro-distortive tilting mode of the MnF6 octahedra around the primitive a0 - and b0 -axes, when cooled down. It is also found that there is another structural phase transition at about 45 K related to a precursor structural distortion for the antiferromagnetic transition occurring at about 26 K.

The capacity loss behavior of LiMn 2 O 4 prepared by emulsion drying method was investigated by cycling experiments giving various cutoff discharge voltages. The discharge capacity loss was also quantified depending on the cutoff discharge voltages. LiMn 2 O 4 cathode showed most capacity loss in the high-voltage region in the 4 V range and no capacity loss in the voltage-drop region. Therefore, it could be concluded that the cubic-to-tetragonal phase change caused by the Jahn–Teller distortion is not the main cause of the capacity loss in the 4 V range.

The layer structure of alternating Langmuir−Blodgett (LB) films of cadmium arachidate (CdAA2) and poly(tert-butyl methacrylate) (PtBMA) was investigated by an X-ray reflection and in-plane diffraction study. The LB films were deposited on a silicon wafer surface pretreated hydrophobically by transferring a behenic acid monolayer, and two or four PtBMA layers are inserted between each CdAA2 bilayer. While CdAA2 homo-LB films are known to show gradual deterioration of the transfer ratio as the number of accumulated layers increases, the alternating LB films maintain the transfer ratio near unity up to 32 layers. The layer spacing of the alternating LB films determined from the position of the Bragg diffraction peaks increases linearly by 9.9 A per PtBMA layer. The lateral lattice structure of CdAA2 in alternating LB films maintains its hexagonal packing structure, as found in CdAA2 monolayers, while the multilayer CdAA2 LB film is known to change its structure from hexagonal to orthorhombic lattice. The spa...

The insertion of LiF for an interlayer material between the Al cathode and tris-(8-hydroxyquinoline) aluminum (Alq3) in the organic light-emitting diodes (OLEDs) provides an improved device performance. The highly occupied molecular orbital (HOMO) level lowering in the Alq3 layer induced by a low-coverage LiF deposition results in the reduction of electron injection barrier height. We investigated the electronic structure of the interface between the ultrathin LiF and the Alq3 layer, using synchrotron x-ray photoelectron emission spectroscopy. The results revealed that the major origin of the HOMO level lowering is not the chemical bonding of dissociated fluorine in the Alq3 layer but the band bending caused by charge redistribution driven by work function difference between LiF and Alq3 layer.

We fabricated trench PbZrxTi1-xO3 (PZT) capacitors that can be used in 256Mbit 1T-1C FRAM devices. The capacitor has 0.25mum diameter and 0.4mum depth. Three layers, Ir(20nm)/PZT(60nm)/Ir(20nm), were deposited in SiO2 trench holes by ALD and MOCVD. Both columnar and granular grains were formed on the sidewalls of the trench capacitors, and their relative portion had strong size dependence. The trench capacitors with more columnar PZT grains showed good switching behavior under 2.1V external bias and 19 to 24 muC/cm2 remnant polarization

We have discussed a cross-linked polyethylene (XLPE) nanocomposite insulating material that is able to DC voltage applications. Nanocomposites, which are composed in polymer matrix mixed with nano-fillers, have received considerable attention because of their potential benefits as dielectrics. The nano-sized alumina oxide (Al2O3)/XLPE nanocomposite was prepared, and three kinds of test, such as DC breakdown, DC polarity reversal breakdown, and volume resistivity were performed. By the addition of nano-sized Al2O3 filler, both the DC breakdown strength and the volume resistivity of XLPE were increased. A little homogeneous space charge was observed in Al2O3/XLPE nanocomposite material in the vicinity of electrode through the polarity reversal breakdown test. From these results, it is thought that the addition of Al2O3 nano-filler is effective for the improvement of DC electrical insulating properties of XLPE.

The structural and electrical properties of amorphous BaSm Ti O (BSmT) films on a TiN/SiO /Si substrate deposited using a RF magnetron sputtering method were investigated. The deposition of BSmT films was carried out at 300 C in a mixed oxygen and argon (O : Ar = 1 : 4) atmosphere with a total pressure of 8.0 mTorr. In particular, a 45 nm-thick amorphous BSmT film exhibited a high capacitance density and low dissipation factor of 7.60 fF/µm2 and 1.3%, respectively, with a dielectric constant of 38 at 100 kHz. Its capacitance showed very little change, even in GHz ranges from 1.0 GHz to 6.0 GHz. The quality factor of the BSmT film was as high as 67 at 6 GHz. The leakage current density of the BSmT film was also very low, at approximately 5.11 nA/cm at 2 V; its conduction mechanism was explained by the the Poole-Frenkel emission. The quadratic voltage coefficient of capacitance of the BSmT film was approximately 698 ppm/V , which is higher than the required value (