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排序方式: 共有181条查询结果,搜索用时 31 毫秒
91.
Byong Sun Chun Jae Youn Hwang Jang Roh Rhee Taewan Kim Shin Saito Satoru Yoshimura Masakiyo Tsunoda Migaku Takahashi Young Keun Kim 《Journal of magnetism and magnetic materials》2006
Magnetic tunnel junctions (MTJs) comprising amorphous Co70.5Fe4.5Si15B10, possessing low saturation magnetization of 560 emu/cm3, as a free layer have been investigated. The switching behaviours were confirmed for the micrometer-sized elements experimentally, using the scanning magneto-optical Kerr effect (scanning MOKE). A micromagnetic modelling study was also carried out for the submicrometer-sized elements. By using either a CoFeSiB single or a synthetic antiferromagnetic free-layer structure, the magnetization switching field became much lower than conventionally used CoFe free layered MTJs. 相似文献
92.
In this paper, we provide an analytic valuation method for European-type contingent claims written on multiple assets in a stochastic market environment. We employ a two-state Markov regime-switching volatility in order to reflect stochastically changing market conditions. The method is developed by exploiting the probability density of the occupation time for which the underlying asset processes are in a certain regime during a time period. In order to show its usefulness, we derive analytic valuation formulas for quanto options and exchange options with two underlying assets, as examples. 相似文献
93.
Hee Jun Kim Jai Woong Seo Min Hyung Lee Dong Seok Shin Hyeong Baik Kim Hyeongjin Cho Byoung Se Lee Dae Yoon Chi 《Tetrahedron》2012,68(21):3942-3947
A convenient and mild synthetic method of synthesizing benzofuran from various 2-(cyanomethyl)phenyl carbonyl compounds under reduced oxygen conditions is reported. Nine C-2 substituted benzofurans were synthesized at 52–89%. 相似文献
94.
In the present paper, we establish the stability and the superstability of a functional inequality corresponding to the functional equation fn(xyx) = ∑i+j+k=n fi(x)fj (y)fk(x). In addition, we take account of the problem of Jacobson radical ranges for such functional inequality. 相似文献
95.
Wang LC Jang HY Roh Y Lynch V Schultz AJ Wang X Krische MJ 《Journal of the American Chemical Society》2002,124(32):9448-9453
In the presence of phenylsilane and 5 mol % cobalt(II) bis(2,2,6,6-tetramethylheptane-3,5-dionate), aryl-substituted monoenone monoaldehydes and bis(enones) undergo reductive cyclization to afford syn-aldol and anti-Michael products, respectively. For both aldol and Michael cycloreductions, five- and six-membered ring formation occurs in good yield with high levels of diastereoselectivity. Cycloreduction of monoenone monoaldehyde 1a in the presence of d(3)-phenylsilane reveals incorporation of a single deuterium at the enone beta-position as an equimolar mixture of epimers, inferring rapid isomerization of the kinetically formed cobalt enolate prior to cyclization. The deuterated product was characterized by single-crystal neutron diffraction analysis. For bis(enone) substrates, modulation of the silane source enables partitioning of the competitive Michael cycloreduction and [2 + 2] cycloaddition manifolds. A study of para-substituted acetophenone-derived bis(enones) reveals that substrate electronic features also direct partitioning of cycloreduction and cycloaddition manifolds. Further mechanistic insight is obtained through examination of the effects of enone geometry on product stereochemistry and electrochemical studies involving cathodic reduction of bis(enone) substrates. The collective experiments reveal competitive enone reduction pathways. Enone hydrometalation produces metallo-enolates en route to aldol and Michael cycloreduction products, that is, products derived from coupling at the alpha-position of the enone. Electron-transfer-mediated enone reduction produces metallo-oxy-pi-allyls en route to [2 + 2] cycloadducts and, under Ni catalysis, homoaldol cycloreduction products, that is, products derived from coupling at the beta-position of the enone. The convergent outcome of the metal-catalyzed and electrochemically induced transformations suggests the proposed oxy-pi-allyl intermediates embody character consistent with the mesomeric metal-complexed anion radicals. 相似文献
96.
[reaction: see text] OsO(4) was simply immobilized onto resins such as Amberlite XAD-4 or XAD-7 bearing residual vinyl groups. The resulting osmylated resins are air-stable, nonvolatile, and much easier to handle than their homogeneous counterpart (OsO(4)). Moreover, the resin-bound OsO(4) exhibited excellent catalytic activity in the asymmetric dihydroxylation of olefins and was easily recovered and reused in five consecutive reactions without any significant decrease in product yield. Turnover time, however, was significantly increased for the fourth and fifth reactions. 相似文献
97.
We emphasize the importance of the new design concept for diffusion barriers in high-density memory capacitors. RuTiN and
RuTiO films are proposed as sacrificial oxygen diffusion barriers. They showed much lower sheet resistance up to 800 °C than
various barriers including binary and ternary nitrides, reported by others. The contact resistance for both the Pt/RuTiN/TiSix/n++poly-plug/n+channel layer/Si and the Pt/RuTiO/RuTiN/TiSix/n++poly-plug/n+channel layer/Si contact structures, the most important electrical parameter for the diffusion barrier in the bottom-electrode
structure of capacitors, exhibited values as low as 5 kΩ, even after annealing up to 750 °C. When each RuTiN and TiN film
is inserted as a glue layer between the bottom electrode Pt layer in the CVD–BST simple stack-type structure, the thermal
stability of the RuTiN glue layer is observed to be 150 °C higher than that of the TiN glue layer. Moreover, the capacitance
of the PVD–BST simple stack-type structure with a TiN glue layer initially degrades after annealing at 500 °C, and thereafter
failed completely. In the case of RuTiN and the RuTiO/RuTiN glue layers, however, the capacitance continuously increased up
to 550 °C. These new experimental results accommodate the introduction of the sacrificial design concept of diffusion barriers
against oxygen in high-density memory capacitors.
Received: 6 February 2002 / Accepted: 4 March 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax: +82-31/360-4545, E-mail: dongsoo.yoon@hynix.com 相似文献
98.
Development of SH-SAW sensors for underwater measurement 总被引:3,自引:0,他引:3
We developed SH (shear horizontal) surface acoustic wave (SAW) sensors to detect protein molecules in liquid solutions applying a particular antibody thin film on the delay line of transverse SAW devices. The antibody investigated was human-immuno-globulin G (HigG) to hold the antigens (anti-HigG) in the protein solution to be measured. The sensor showed stable response to the mass loading effects of the anti-HigG molecules with the sensitivity up to 10.8 ng/ml/Hz. 相似文献
99.
Do Van Lam Van-Toan Nguyen Euijin Roh Quang-Tung Ngo Wanuk Choi Jae-Hyun Kim Hyunuk Kim Ho-Suk Choi Seung-Mo Lee 《Particle & Particle Systems Characterization》2021,38(9):2100119
Metal nanoparticles encapsulated in graphitic carbon can show high catalytic efficiency and stability, yet the production method remains improved. Herein, it is demonstrated that a Ni-based metal–organic framework [EG-MOF-74(Ni)] can be rapidly transformed into ultrasmall Ni-nanoparticles with different sizes (4–11 nm) encapsulated in graphitic carbon via the laser-scribing method. The synthesized sample shows the best electrocatalytic performances with excellent stability in alkaline electrolyte for oxygen/hydrogen evolution reactions with overpotentials of 0.35/0.18 V at a current density of 10 mA cm−2 when the Ni particle size is ≈6 nm. This is because of its well-developed micro/mesoporous structure, high electronic transport, and large electrochemical active surface area. An electrolyzer with Ni-nanoparticles encapsulated in the graphitic carbon shows a current density of 10 mA cm−2 at a voltage of 1.6 V, which is comparable to the Pt/C and RuO2 counterparts. The laser-based synthesis can serve as a powerful tool for the size-controlled synthesis of various catalysts out of MOFs. 相似文献
100.
In this study, porous ceramic fibers were prepared by the sol–gel-assisted electro-spinning process using colloidal dispersion of complex fluids for the application of phtotocatalysts. First, polystyrene nanospheres were synthesized by dispersion polymerization as sacrificial templates for porous fibers. Then, the mixture of polyvinylpyrrolidone and the ceramic precursor with the polymeric nanospheres was prepared as the spinning solution and self-organized by electro-spinning, followed by calcination of the electrospun composite fibers. The morphologies of the porous fibers could be controlled according to the size of the templates and the amount of the ceramic precursor. The nano-structure of the pores in the fibrous materials could also be adjusted as open or closed cavities with various potential applications. As a demonstrative application, the macroporous titania fibers could be utilized as photocatalysts for the removal of organic dyes dissolved in water. A better photocatalytic activity of the macroporous fibers with 700-nm pore diameter was observed compared to the result of nonporous titania fibers due to the increased porosity. Collectively, the macroporous ceramic fibers were found to be efficient functional materials to prepare the unique nano-structured materials other than simple nonporous fibers. 相似文献