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891.
Michael Quinones Yazhou Zhang Penelope Riascos Huey‐Min Hwang Winfred G. Aker Xiaojia He Ruomei Gao 《Photochemistry and photobiology》2014,90(2):374-379
Many biomolecules contain photoactive reducing agents, such as reduced nicotinamide adenine dinucleotide (NADH) and 6‐thioguanine (6‐TG) incorporated into DNA through drug metabolism. These reducing agents may produce reactive oxygen species under UVA irradiation or act as electron donors in various media. The interactions of C60 fullerenes with biological reductants and light energy, especially via the Type‐I electron‐transfer mechanism, are not fully understood although these factors are often involved in toxicity assessments. The two reductants employed in this work were NADH for aqueous solutions and 6‐TG for organic solvents. Using steady‐state photolysis and electrochemical techniques, we showed that under visible light irradiation, the presence of reducing agents enhanced C60‐mediated Type‐I reactions that generate superoxide anion (O2.?) at the expense of singlet oxygen (1O2) production. The quantum yield of O2.? production upon visible light irradiation of C60 is estimated below 0.2 in dipolar aprotic media, indicating that the majority of triplet C60 deactivate via Type‐II pathway. Upon UVA irradiation, however, both C60 and NADH undergo photochemical reactions to produce O2.?, which could lead to a possible synergistic toxicity effects. C60 photosensitization via Type‐I pathway is not observed in the absence of reducing agents. 相似文献
892.
Ping-Chung Kuo Yue-Chiun Li Tsong-Long Hwang Guo-Hao Ma Mei-Lin Yang E-Jian Lee Tian-Shung Wu 《Tetrahedron letters》2014
Linderaggrine A (1) was characterized from the roots of Lindera aggregata and its chemical structure was established by the spectral analysis and chemical transformation. The chemical preparation of 1 and its isomer 2 provide unambiguous evidences for the structural determination of the naturally isolated compound. In addition, the inhibition of superoxide anion generation and elastase release by human neutrophils in response to FMLP/cytochalasin B of these synthetic products had been examined and among the tested compounds, linderaggrine A (1) displayed significant potential against the superoxide anion generation. 相似文献
893.
TiO2 and Al‐doped TiO2 (ATO) films were grown on Ir substrates by atomic layer deposition using O3 as the oxygen source. With increasing O3 feeding time, the crystalline structure of the TiO2 films was transformed from anatase to rutile. Above an O3 feeding time of 35 s, the films crystallized as only rutile due to the formation of IrO2 layer at the interface. The TiO2 and ATO films showed higher dielectric constants of 78 and 51, respectively. The films on Ir showed superior leakage properties compared to the films on Ru due to the high work‐function of Ir. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
894.
Kwang-seok Hwang Ki-hyun Lee In-ho Kim Jin-Won Lee 《Journal of nanoparticle research》2011,13(10):4979-4986
Removal of nanometer-sized contaminant particles (CPs) from substrates is essential to successful fabrication of nano scale
devices. But the cleaning limit of various current technologies stay around 50 nm. Cryogenic aerosol beam has long been successfully
employed to remove CPs down to 50 nm, and supersonic particle beam using particles smaller than 100 nm lowered the limit of
cleaning down to 20 nm size. In this study, the particle beam technique that uses nanometer-sized bullet particles moving
at supersonic velocity was improved, and successfully employed to remove contaminant particles as small as 10 nm. Ar nano-bullets
of about 20–50 nm were generated by gas-phase nucleation, and growth in a supersonic nozzle: appropriate size and velocity
of the nano-bullets were obtained by optimizing the Ar/He mixture fraction and nozzle contours. Cleaning efficiency >95% was
attained. Nano-bullet velocity was found to be the most important parameter affecting removal of contaminant particles in
the 10-nm size range. 相似文献
895.
T. Hwang C. C. Hwang C. W. Tsai 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(3):785-790
The three-qubit W state, with an important feature that each pair
of it’s qubits has the same and maximum amount of bipartite entanglement,
can be reduced to an entangled 2-qubit system if one of its qubits
is lost. Recently, Xue et al. proposed a three-party quantum secret
sharing (QSS) protocol based on the three-qubit W state [Chinese Phys. 15, 7 (2006)]. Also, Joo
et al. proposed a pair-wise quantum key distribution protocol among
three users based on a special measurement on the three-qubit W state [eprint arXiv:quant-ph/0204003v2 (2002)].
This study aims to propose a novel quantum key distribution protocol
(QKDP) for arbitrary two communications based on the dense coding
and the special measurement of three-qubit W state with the X basis
and the Z basis. 相似文献
896.
Hyung-Joon Cho Poong-Gok Hwang Dongwoon Jung 《Journal of Physics and Chemistry of Solids》2011,72(12):1462-1466
TiO2 hollow nanospheres were prepared using silicon oxide as a template. N-doped titanium oxide hollow spheres, TiO2−xNx were synthesized by reacting TiO2 hollow spheres with thiourea at 500 °C. XRD and XPS data showed that oxygen was successfully substituted by nitrogen through the nitrogen-doping reaction, and finally N-doped TiO2 hollow spheres were formed. The N-doped TiO2 hollow spheres showed new absorption shoulder in visible light region so that they were expected to exhibit photocatalytic activity in the visible light. The photocatalytic activity of N-doped TiO2 hollow spheres under visible light was similar to that of normal spherical TiO2−xNx in spite of the structural difference. 相似文献
897.
Pototschnig M Chassagneux Y Hwang J Zumofen G Renn A Sandoghdar V 《Physical review letters》2011,107(6):063001
We employ heterodyne interferometry to investigate the effect of a single organic molecule on the phase of a propagating laser beam. We report on the first phase-contrast images of individual molecules and demonstrate a single-molecule electro-optical phase switch by applying a voltage to the microelectrodes embedded in the sample. Our results may find applications in single-molecule holography, fast optical coherent signal processing, and single-emitter quantum operations. 相似文献
898.
Ishida Y Kanto H Kikkawa A Taguchi Y Ito Y Ota Y Okazaki K Malaeb W Mulazzi M Okawa M Watanabe S Chen CT Kim M Bell C Kozuka Y Hwang HY Tokura Y Shin S 《Physical review letters》2011,107(7):077601
Circular dichroism in the angular distribution of photoelectrons from SrTiO(3):Nb and Cu(x)Bi(2)Se(3) is investigated by 7-eV laser angle-resolved photoemission spectroscopy. In addition to the well-known node that occurs in the circular dichroism pattern when the incidence plane matches the mirror plane of the crystal, we show that another type of node occurs when the mirror plane of the crystal is vertical to the incidence plane and the electronic state is two-dimensional. The flower-shaped circular dichroism patterns in the angular distribution occurring around the Fermi level of SrTiO(3):Nb and around the Dirac point of Cu(x)Bi(2)Se(3) are explained on equal footings. We point out that the penetration depth of the topological states of Cu(x)Bi(2)Se(3) depends on momentum. 相似文献
899.
Hae-geun Jee Jin-Hee Han Han-Na Hwang Young Dok Kim Chan-Cuk Hwang 《Surface science》2011,605(7-8):649-653
Adsorption and desorption of fullerene on a single layer of graphene grown on SiC(0001) were investigated by photoemission spectroscopy (PES). No significant change in the band structure of graphene was observed after fullerene deposition on the graphene layer under vacuum conditions, and subsequent exposure to the air. After annealing the fullerene layer at 275 °C in a vacuum, complete desorption of fullerene was observed without any resulting damage to the graphene structure. The desorption temperature of fullerene was significantly higher than that of pentacene, indicating that fullerene layers show higher stability than pentacene as protection layers of graphene-based devices. 相似文献
900.
Cho WB Kim JW Lee HW Bae S Hong BH Choi SY Baek IH Kim K Yeom DI Rotermund F 《Optics letters》2011,36(20):4089-4091
High-quality monolayer graphene as large as 1.2×1.2?cm2 was synthesized by chemical vapor deposition and used as a transmitting saturable absorber for efficient passive mode-locking of a femtosecond bulk solid-state laser. The monolayer graphene mode-locked Cr:forsterite laser was tunable around 1.25?μm and delivered sub-100?fs pulses with output powers up to 230?mW. The nonlinear optical characteristics of the monolayer graphene saturable absorber and the mode-locked operation were then compared with the case of the bilayer graphene saturable absorber. 相似文献