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Search Results: 1 - 10 of 1746 matches for " In Hyuk Jang "
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Spin polarized electron transport near the Si/SiO2 interface
Hyuk-Jae Jang,Ian Appelbaum
Physics , 2009, DOI: 10.1103/PhysRevLett.103.117202
Abstract: Using long-distance lateral devices, spin transport near the interface of Si and its native oxide (SiO2) is studied by spin-valve measurements in an in-plane magnetic field and spin precession measurements in a perpendicular magnetic field at 60K. As electrons are attracted to the interface by an electrostatic gate, we observe shorter average spin transit times and an increase in spin coherence, despite a reduction in total spin polarization. This behavior, which is in contrast to the expected exponential depolarization seen in bulk transport devices, is explained using a transform method to recover the empirical spin transit-time distribution and a simple two-stage drift-diffusion model. We identify strong interface-induced spin depolarization (reducing the spin lifetime by over two orders of magnitude from its bulk transport value) as the consistent cause of these phenomena.
Isolation and identification of alkaloids and anthocyanins from flower and bulb of Lycoris radiata using HPLC and LC-ESI-MS  [PDF]
Jin-Hyuk Chun, In Hyuk Jang, Mariadhas Valan Arasu, Naif Abdullah Al-Dhabi, Veeramuthu Duraipandiyan, Dong-Hoon Lee, Sanghyun Lee, Sun-Ju Kim
Journal of Agricultural Chemistry and Environment (JACEN) , 2013, DOI: 10.4236/jacen.2013.21004
Abstract: Three anthocyanins (cyanidin 3-diglucoside, cyanidin 3-sambubioside and cyanidin 3-glucoside) together with eleven known alkaloids (lycoricidine, hipppeastrine,O-Demethyllycoramin, lycoricidinol, galanthine, lycorine, lycorenine, lycoramine, galanthamine, homolycorine and pretazettine) were identified in the flower and bulb of Lycoris radiata using high-performance liquid chromatography coupled with UV detection and electrospray ionization mass spectrometry. Anthocyanins play a major role in protecting plant’s DNA from the UV spectrum of sunlight and also in attracting insects for the purpose of pollination. Thus, knowledge on the contents and types of anthocyanins of L. radiata will help to evaluate the adaptive evolution of flowers and provide useful information for the ornamental breeding.
Rapid Hydrothermal Synthesis of Zinc Oxide Nanowires by Annealing Methods on Seed Layers
Jang Bo Shim,Hyuk Chang,Sung-O Kim
Journal of Nanomaterials , 2011, DOI: 10.1155/2011/582764
Abstract: Well-aligned zinc oxide (ZnO) nanowire arrays were successfully synthesized on a glass substrate using the rapid microwave heating process. The ZnO seed layers were produced by spinning the precursor solutions onto the substrate. Among coatings, the ZnO seed layers were annealed at 100°C for 5 minutes to ensure particle adhesion to the glass surface in air, nitrogen, and vacuum atmospheres. The annealing treatment of the ZnO seed layer was most important for achieving the high quality of ZnO nanowire arrays as ZnO seed nanoparticles of larger than 30 nm in diameter evolve into ZnO nanowire arrays. Transmission electron microscopy analysis revealed a single-crystalline lattice of the ZnO nanowires. Because of their low power (140 W), low operating temperatures (90°C), easy fabrication (variable microwave sintering system), and low cost (90% cost reduction compared with gas condensation methods), high quality ZnO nanowires created with the rapid microwave heating process show great promise for use in flexible solar cells and flexible display devices.
Efficiency Control in Iridium Complex-Based Phosphorescent Light-Emitting Diodes
Boucar Diouf,Woo Sik Jeon,Ramchandra Pode,Jang Hyuk Kwon
Advances in Materials Science and Engineering , 2012, DOI: 10.1155/2012/794674
Abstract: Key factors to control the efficiency in iridium doped red and green phosphorescent light emitting diodes (PhOLEDs) are discussed in this review: exciton confinement, charge trapping, dopant concentration and dopant molecular structure. They are not independent from each other but we attempt to present each of them in a situation where its specific effects are predominant. A good efficiency in PhOLEDs requires the triplet energy of host molecules to be sufficiently high to confine the triplet excitons within the emitting layer (EML). Furthermore, triplet excitons must be retained within the EML and should not drift into the nonradiative levels of the electron or hole transport layer (resp., ETL or HTL); this is achieved by carefully choosing the EML’s adjacent layers. We prove how reducing charge trapping results in higher efficiency in PhOLEDs. We show that there is an ideal concentration for a maximum efficiency of PhOLEDs. Finally, we present the effects of molecular structure on the efficiency of PhOLEDs using red iridium complex dopant with different modifications on the ligand to tune its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies. 1. Introduction Achievements in organic light emitting diodes (OLEDs) lead to their integration as displays in several electronic devices and make them serious candidates to replace widely used LCD panels. Extensive research efforts have been made for higher achievements in organic displays both in industrial and academic fields [1–10]. In organic light-emitting devices (OLEDs), injected electrons and holes in the emitter will attract each other to form excitons [11–20]. Spin statistics demonstrate that the ratio between singlet and triplet excitons is one to three. In fluorescent OLEDs only the singlet excitons can generate radiative recombinations, giving a maximum inherent quantum efficiency of 25% [21–23], with no phosphorescent light radiation. On the other hand, triplet emitters can harvest both singlet and triplet radiative recombinations reaching a theoretical internal quantum efficiency of 100% [24–26]. Iridium and platinum complexes present good phosphorescent emission properties [27–29]. Iridium (III) complexes are the most widely used dopants in PhOLEDs because of their higher triplet efficiency [30–35]. PhOLEDs harvest both singlet and triplet emissions, making it possible to reach high efficiency devices. However, their operation and efficient implementation are more complex than for the fluorescent OLEDs. To achieve high efficiency in PhOLEDs, the
Geometric dephasing-limited Hanle effect in long-distance lateral silicon spin transport devices
Biqin Huang,Hyuk-Jae Jang,Ian Appelbaum
Physics , 2008, DOI: 10.1063/1.3006333
Abstract: Evidence of spin precession and dephasing ("Hanle effect") induced by an external magnetic field is the only unequivocal proof of spin-polarized conduction electron transport in semiconductor devices. However, when spin dephasing is very strong, Hanle effect in a uniaxial magnetic field can be impossible to measure. Using a Silicon device with lateral injector-detector separation over 2 millimeters, and geometrically-induced dephasing making spin transport completely incoherent, we show experimentally and theoretically that Hanle effect can still be measured using a two-axis magnetic field.
Non-ohmic spin transport in n-type doped silicon
Hyuk-Jae Jang,Jing Xu,Jing Li,Biqin Huang,Ian Appelbaum
Physics , 2007, DOI: 10.1103/PhysRevB.78.165329
Abstract: We demonstrate the injection and transport of spin-polarized electrons through n-type doped silicon with in-plane spin-valve and perpendicular magnetic field spin precession and dephasing ("Hanle effect") measurements. A voltage applied across the transport layer is used to vary the confinement potential caused by conduction band-bending and control the dominant transport mechanism between drift and diffusion. By modeling transport in this device with a Monte-Carlo scheme, we simulate the observed spin polarization and Hanle features, showing that the average transit time across the short Si transport layer can be controlled over 4 orders of magnitude with applied voltage. As a result, this modeling allows inference of a long electron spin lifetime, despite the short transit length.
High Speed CAN Transmission Scheme Supporting Data Rate of over 100 Mbps
Suwon Kang,Sungmin Han,Seungik Cho,Donghyuk Jang,Hyuk Choi,Ji-Woong Choi
Mathematics , 2015,
Abstract: As the number of electronic components in the car increases, the requirement for the higher data transmission scheme among them is on the sharp rise. Controller area network (CAN) has been widely adopted to support the in-car communications needs but the data rate is far below what other schemes such as Ethernet and optical fibers can offer. A new scheme for enhancing the speed of CAN network has been proposed, where carrier modulated signal is introduced on top of the existing CAN signal whereby the data rate can be enhanced over 100Mbps. The proposed scheme is compatible with the existing CAN network and accordingly enables seamless upgrade of the existing network to support high speed demand using CAN protocol.
Identification and Determination of Phenolic Compounds in Rapeseed Meals (Brassica napus L.)  [PDF]
Si-Chang Yang, Mariadhas Valan Arasu, Jin-Hyuk Chun, Young-Seok Jang, Yong-Hwa Lee, In Ho Kim, Ki-Taek Lee, Soon-Taek Hong, Sun-Ju Kim
Journal of Agricultural Chemistry and Environment (JACEN) , 2015, DOI: 10.4236/jacen.2015.41002
Abstract: This study aimed in the identification and quantification of phenolic compounds in different four varieties of rapeseeds (Brassica napus L.) using LC-MS and HPLC. LC-MS analysis guided to identify 12 phenolic compounds including sinapine, sinapine(4-O-8')guaiacyl, feruloyl choline(4-O-8') guaiacyl, kaempferol-3-O-sinapoyl-sophoroside-7-O-glucoside, kaempferol-3-O-β-sophoroside, cyclic spermidine-alkaloid, feruloyl choline(5-8')guaiacyl, kaempferol-sinapoyl-trihexoside,1,2-di- O-sinapoyl-gentiobiose, 1,2-di-O-sinapoyl-glucose, feruloyl choline(4-O-8')guaiacyl-di-sinapoyl, and sinapine(4-O-8')guaiacyl-di-sinapoyl, respectively. Total phenolic compounds in rapeseed meals were ranged from 38.50 (2012 “Sunmang”) to 63.95 mg/g dry weight (DW) (2014 Jeju local cultivar). Main phenolic compositions were cyclic spermidine-alkaloid, kaempferol, feruloyl choline, and sinapine. Sinapine was predominant compound among all the samples ranged from 29.74 to 52.24 mg/g DW (mean 79% of total phenolic contents). This study provided the information for the variation of phenolic compounds between the varieties of rapeseeds and the cultivation periods. Furthermore, this information can be developed for bio-energy industry as a reducer of the cost of the bio-energy products.
Prolonged ozone exposure in an allergic airway disease model: Adaptation of airway responsiveness and airway remodeling
An-Soo Jang, Inseon-S Choi, Jae-Hyuk Lee, Chang-Soo Park, Choon-Sik Park
Respiratory Research , 2006, DOI: 10.1186/1465-9921-7-24
Abstract: We exposed BALB/c mice to 2 ppm ozone for 4, 8, and 12 weeks. We measured the enhanced pause (Penh) to methacholine and performed cell differentials in bronchoalveolar lavage fluid. We quantified the levels of IL-4 and IFN-γ in the supernatants of the bronchoalveolar lavage fluids using enzyme immunoassays, and examined the airway architecture under light and electron microscopy.The groups exposed to ozone for 4, 8, and 12 weeks demonstrated decreased Penh at methacholine concentrations of 12.5, 25, and 50 mg/ml, with a dose-response curve to the right of that for the filtered-air group. Neutrophils and eosinophils increased in the group exposed to ozone for 4 weeks compared to those in the filtered-air group. The ratio of IL-4 to INF-γ increased significantly after exposure to ozone for 8 and 12 weeks compared to the ratio for the filtered-air group. The numbers of goblet cells, myofibroblasts, and smooth muscle cells showed time-dependent increases in lung tissue sections from the groups exposed to ozone for 4, 8, and 12 weeks.These findings demonstrate that the increase in AHR associated with the allergic airway does not persist during chronic ozone exposure, indicating that airway remodeling and adaptation following repeated exposure to air pollutants can provide protection against AHR.Asthma is characterized by the presence of a variable airflow limitation, airway hyper-responsiveness (AHR), and airway inflammation [1]. Acute exposure to ozone, which is an important component of the photochemical oxidation products of substrates emitted as air pollution from automobile engines [2], decreases pulmonary function, increases AHR, and induces airway inflammation in dogs [3], guinea pigs [4], and humans [5-7]. Chronic airway inflammation is associated with airway remodeling that includes airway wall thickening as a result of inflammatory and structural changes, such as edema; inflammatory cell infiltration; mucous gland hyperplasia; reticular basement membrane thicke
Ethyl pyruvate attenuates formalin-induced inflammatory nociception by inhibiting neuronal ERK phosphorylation
Min Jung Lee, Minhee Jang, Hyuk-Sang Jung, Sung-Hoon Kim, Ik-Hyun Cho
Molecular Pain , 2012, DOI: 10.1186/1744-8069-8-40
Abstract: EP significantly decreased formalin-induced nociceptive behavior during phase II, the magnitude of paw edema, and the activation of c-Fos in L4-L5 spinal dorsal horn. EP also attenuated the phosphorylation of extracellular signal-regulated kinase (ERK) in the neurons of L4-L5 spinal dorsal horn after formalin injection. Interestingly, the i.t. administration of PD98059, an ERK upstream kinase (MEK) inhibitor, completely blocked the formalin-induced inflammatory nociceptive responses.These results demonstrate that EP may effectively inhibit formalin-induced inflammatory nociception via the inhibition of neuronal ERK phosphorylation in the spinal dorsal horn, indicating its therapeutic potential in suppressing acute inflammatory pain.
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