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Journal of Nanoscience and Nanotechnology

Ruijiang Liu, Dan Chen, Hongxia Fu, Pingxue Lv, Die Zhang, Yunjie He
A facile sol combustion and gel calcination process has been reported for the preparation of core– shell magnetic Zn0.5Fe₂O₄@SiOnanocomposites. The morphology, chemical composition, structure and magnetic property of as-prepared nanocomposites were investigated by XRD, VSM, BET, SEM, and TEM, and the magnetic Ni0.5Zn0.5Fe₂O₄@SiO₂ nanocomposites were characterized with average size of about 25 nm, saturation magnetization of 90.8 Am²/kg and the specific surface area of 67.1 m2/g. The surface of Ni0...
July 2201: Journal of Nanoscience and Nanotechnology
Sang Chul Jung, Young-Kwon Park, Ho-Young Jung, Sang Chai Kim
The effects of stabilizing agents and the reaction conditions on the synthesis of palladium nanoparticles were examined. Palladium nanoparticles were prepared using palladium (II) chloride (PdCl2) as a precursor and sodium borohydride (NaBH4) as the reducing agent. Polyvinylpyrrolidone, sodium dodecyl sulfate and cetyltrimethylammonium bromide were used as the stabilizing agents. Transmission electron microscopy and X-ray diffraction were used to characterize the prepared palladium nanoparticles. The size of the palladium nanoparticles was dependent on the concentration of the precursor, reaction temperature, and stirring rate...
July 2201: Journal of Nanoscience and Nanotechnology
Seung Mi Lee, Min-Young Kim, Young Heon Kim
We investigated the effects of strain on the electronic structures of InAsxP1-x using quantum mechanical density functional theory calculations. The electronic band gap and electron effective mass decreased with the increase of the uniaxial tensile strain along the [0001] direction of wurtzite InAs0.75P0.25. Therefore, faster electron movements are expected. These theoretical results are in good agreement with the experimental measurements of InAs0.75P0.25 nanowire.
September 1, 2018: Journal of Nanoscience and Nanotechnology
Geon Hyeong Lee, Young Sik Kim
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...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Geon Hyeong Lee, Young Sik Kim
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...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Geon Hyeong Lee, Young Sik Kim
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...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Won-Ho Lee, Jong-Chul Lee
A numerical simulation was developed for magnetic nanoparticles in a liquid dielectric to investigate the AC breakdown voltage of the magnetic nanofluids according to the volume concentration of the magnetic nanoparticles. In prior research, we found that the dielectric breakdown voltage of the transformer oil-based magnetic nanofluids was positively or negatively affected according to the amount of magnetic nanoparticles under a testing condition of dielectric fluids, and the trajectory of the magnetic nanoparticles in a fabricated chip was visualized to verify the related phenomena via measurements and computations...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Youn-Jea Kim, Jong-Chul Lee
A SF6 self-blast switching chamber belongs to a new generation of high-voltage switching devices, which take advantage of the auto-expansion principle and arc rotation to improve the switching performance on thermal and dielectric interruptions. The thermal behaviors between the arc plasma and the electrodes in the device are very complex to understand only through experimental studies. Since the late nineteen-eighties, significant progress has been made in computational methods describing the physical processes occurring in thermal plasmas...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Hong-Seok Jang, Ju-Hee Kim, Xing Shuli, Seung-Young So
Colored concrete uses pigments and white Portland cement (WPC) to perform decorative functions together with structural function. Pigments are used in permanent coloring of concrete with colors different from the natural color of the cement or the aggregates with mixing WPC. In this study, an artificial neural networks study was carried out to predict the color evaluation of black mortar using pigment and carbon black. A data set of a laboratory work, in which a total of 9 mortars were produced, was utilized in the Artificial Neural Networks (ANNs) study...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Karam Cho, Changhwan Shin
Nanoelectromechanical (NEM) relays have been studied for use in low-power logic applications because of their conspicuous features of (i) zero off-state leakage and (ii) abrupt on/off switching behavior in principle. In this study, a lateral NEM relay is analytically modeled. Then, the pull-in/out voltages, which work as turn-on/off voltages for the device, are estimated quantitatively using equations that explain the operational principle of the NEM relay. Exemplary design parameters are proposed to ensure the operation of the NEM relay as a logic device, and its transfer characteristics are analyzed...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Won-Ho Lee, Youn-Jea Kim, Jong-Chul Lee
Metal nanoparticles are used in applications ranging from bio-diagnostics to catalysis due to the expectation to improve attributes or the performance of specific products or processes. The electric arc can be used to produce metal nanoparticles by evaporating the anode and forming the anode vapor. In order to synthesize the nanoparticles of the desired properties, the influence of various input parameters on the growth kinetics has to be fully understood. In this study, we presented two and three dimensional results of numerical simulation of the transferred electric arc taking into account the interaction model between an electric arc and two electrodes...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Yeon-Ho Lee, Hyun-Oh Kim, Youn-Jea Kim
Stretchable heaters are mechanically and biomedically advantageous because they are more flexible than the conventional microheaters. To determine the way that a heater can be used appropriately in a wide range of application fields, studies on the mechanical and thermal characteristics regarding various film configurations are underway. In this study, the mechanical characteristics of conical-frustum-patterned stretchable heaters with various configurations with upper-radius (R1), bottom-radius (R2), and height (h) aspect ratios were numerically investigated when tensile forces and bending moments were applied to the film of heater...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Jae Hwa Seo, Young Jun Yoon, In Man Kang
The Ge/GaAs-based heterojunction gate-all-around (GAA) arch-shaped tunneling field-effect transistor (A-TFET) have been designed and optimized using technology computer-aided design (TCAD) simulations. In our previous work, the silicon-based A-TFET was designed and demonstrated. However, to progress the electrical characteristics of A-TFET, the III-V compound heterojunction structures which has enhanced electrical properties must be adopted. Thus, the germanium with gallium arsenide (Ge/GaAs) is considered as key materials of A-TFET...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Jiwon Kim, Hyeongwan Oh, Bo Jin, Rock-Hyun Baek, Jeong-Soo Lee
The analog figure-of-merits (FOMs) of conventional inversion-mode (IM) and junctionless (JL) NanoWire Field Effect Transistor (NWFET) have been investigated, considering the gate Work-Function Variability (WFV) and Random Discrete Dopant (RDD) using 3-dimensional (3D) TCAD simulation. While the JL-NWFET shows higher immune to WFV on analog FOMs, it can be easily affected by RDD due to higher channel doping level. On the other hand, the IM-NWFET shows stronger correlation between transconductance (gm) and gate capacitance (Cgg), leading to similar variation in cut-off frequency (ft) even though it shows larger gm and Cgg variation compared to JL-NWFET...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Bo Gyeong Kim, Jae Hwa Seo, Young Jun Yoon, Min Su Cho, Eunseon Yu, Jung-Hee Lee, Seongjae Cho, In Man Kang
In this study, one-transistor dynamic random-access memory (1T-DRAM) based on a symmetric double-gate Si junctionless transistor is proposed using technology computer-aided design simulation. The proposed device uses double gates that play different roles in realizing 1T-DRAM operation. Gate 1 is used as a switching node, and Gate 2 is used as a storage node. By controlling the different two gate workfunctions, a potential barrier is adjusted to store hole effectively. The operation characteristics were investigated regarding four different memory operation states to write "1", write "0", read, and hold...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Min-Woo Kwon, Myung-Hyun Baek, Sungmin Hwang, Sungjun Kim, Byung-Gook Park
We designed the CMOS analog integrate and fire (I&F) neuron circuit can drive resistive synaptic device. The neuron circuit consists of a current mirror for spatial integration, a capacitor for temporal integration, asymmetric negative and positive pulse generation part, a refractory part, and finally a back-propagation pulse generation part for learning of the synaptic devices. The resistive synaptic devices were fabricated using HfOx switching layer by atomic layer deposition (ALD). The resistive synaptic device had gradual set and reset characteristics and the conductance was adjusted by spike-timing-dependent-plasticity (STDP) learning rule...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Taejin Jang, Myung-Hyun Baek, Hyungjin Kim, Byung-Gook Park
In this paper, we demonstrate the characteristics of the floating body effect of poly-silicon with grain boundary by SENTAURUS™ TCAD simulation. As drain voltage increases, impact ionization occurs at the drain-channel junction. And these holes created by impact ionization are deposited on the bottom of the body to change the threshold voltage. This feature, the kink effect, is also observed in fully depleted silicon on insulator because grain boundary of the poly-silicon serve as a storage to trap the holes...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Faraz Najam, Yun Seop Yu
Corner-effect existing in L-shaped tunnel field-effect-transistor (LTFET) was investigated using numerical simulations and band diagram analysis. It was found that the corner-effect is caused by the convergence of electric field in the sharp source corner present in an LTFET, thereby increasing the electric field in the sharp source corner region. It was found that in the corner-effect region tunneling starts early, as a function of applied bias, as compared to the rest of the channel not affected by corner-effect...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Han Pill Song, Ji Yeon Jang, So Hyeon Bae, Seong Bong Choi, Byung Jo Yu, Moon Il Kim
Cerium oxide nanoparticles, also called nanoceria, have recently gained much attention as oxidase-mimicking nanozymes that catalyze the oxidation of chromogenic substrates for color generation without the addition of H2O2. Herein, we have developed a unique colorimetric biosensor for thrombin in human blood plasma, which relies on thrombin-binding aptamer (TBA)-mediated inhibition of the oxidase activity of nanoceria and its restoration by very selective interactions of TBA with target thrombin. In this system, nanoceria were first incubated with TBA, resulting in quick reduction of the oxidase activity of nanoceria via the adsorption of single-stranded (ss)DNA-type TBA on nanoceria...
September 1, 2018: Journal of Nanoscience and Nanotechnology
Young-Jun Lee, Jong-Gyu Kim, Joo-Hyung Kim, Jaesook Yun, Won Jun Jang
The detection and monitoring of colorless and odorless chemical warfare agents (CWAs) has become important due to the increasing threat of terrorist activities. To enhance the sensitivity and selectivity of CWAs a number of sensing materials have been developed, including the widely used polyvinylidene fluoride (PVDF). However, PVDF is limited by its low sensitivity and selectivity for many CWAs. In this study, polyhedral oligomeric silsesquioxane (POSS) was used as a sensing material for dimethyl methylphosphonate (DMMP) a simulant of sarin nerve gas...
September 1, 2018: Journal of Nanoscience and Nanotechnology
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