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101.
The inhibition effect of polyvinylprrolidone (PVP) during dealloying on the formation of nanoporous Cu from a Ti60Cu40 amorphous alloy in hydrofluoric acids (HF) was investigated. A bicontinuous nanoporous Cu structure formed on Ti60Cu40 after dealloying. The pore size of nanoporous Cu formed in HF solution was 71 nm, but this decreased to 12 nm and 11 nm after dealloying for the same period of dealloying time of 43.2 ks when 0.01 M and 0.03 M PVP, respectively, was added into the 0.03 M HF base solution. The surface diffusivity was estimated to decrease from 2.5 × 10−18 m2 s−1 in 0.03 M HF solution to 1.84 × 10−21 m2 s−1 when 0.01 M PVP was added, and to 1.42 × 10−21 m2 s−1 when 0.03 M PVP was added. More PVP macromolecules were adsorbed onto the nanoporous Cu surface in the 0.03 M HF solution with the addition of 0.03 M PVP than when 0.01 M PVP was added to the solution, which resulted in the formation of smaller nanopores. The suppressed diffusion of Cu adatoms due to the PVP macromolecule resulted in the formation of finer Cu ligaments than that formed in 0.03 M HF solution. This long chain organic molecule was shown to act as a diffusion barrier for the diffusion of metal adatoms during dealloying and to elaborate the nanoporous structure. 相似文献
102.
Takahiko Hara 《Sequential Analysis》2013,32(2):115-124
The paper deals with two kinds of location-slippage testing problems.The alternative hypothesis says that there is a single slippage in one kind of problems,and that there are multiple slippages in the other kind. In a location slippage model, by using Robbins' inequality, Robbins-Lai's invariant confidence sequences for slippage are constructed for both of the problems and sequential slippage tests using those confidence sequences are proposed. 相似文献
103.
Lossless broadband microwave active inductors for general-purpose use in microwave circuits are proposed, and their characteristics are discussed. These active inductors are composed of a common-source cascode FET and a feedback FET, and operate in a wide frequency range with very low series resistance. Their low-loss characteristics are demonstrated by simulation and experimental results. A maximum Q factor of 65 is obtained. Theoretically, it can reach infinity. The inductance value can be controlled by an external voltage control 相似文献
104.
The transformation-defective mutant of Rous sarcoma virus (RSV), tdPH2010, has a gag p19 (matrix; MA) protein which migrates on SDS-polyacrylamide gels faster than that of the parental (tsNY68) as well as other wild-type strains of RSV. To study the molecular basis of this altered migration pattern and its biological significance, the nucleotide sequence of the p19 region of tdPH2010 was determined. Comparison of the nucleotide sequence of tdPH2010 with that of the Schmidt-Ruppin A strain of RSV revealed a point mutation at nucleotide 755 (G to A), resulting in an amino-acid substitution at residue 126 of p19 (Glu to Lys). Acidic-methanol esterification of free carboxyl groups suppressed the difference in electrophoretic mobility of p19 between tdPH2010 and the wild-type virus. Recombinant virus constructs having the mutated gag region of tdPH2010 produced a p19 with the same electrophoretic mobility as the p19 of tdPH2010. We concluded that the point mutation caused the altered electrophoretic behavior of p19 of tdPH2010. The mutation had no effect on the growth of infected cells. 相似文献
105.
Overview of multicarrier CDMA 总被引:43,自引:0,他引:43
The authors present an overview of new multiple access schemes based on a combination of code division and multicarrier techniques, such as multicarrier code-division multiple access (MC-CDMA), multicarrier direct sequence CDMA (multicarrier DS-CDMA), and multitone CDMA (MT-CDMA) 相似文献
106.
The purpose is to realize miniaturized and broadband function blocks with very simple configurations for multifunction monolithic microwave circuits. FET-sized combiners and dividers, in phase and out of phase, based on a novel line-unified-FET (LUFET) concept are described and demonstrated. Some effective extensions such as extended combiner LUFETs, magic T LUFETs, and phase inverter LUFETs are also described. The extension of the basic combiner and divider LUFETs allows the realization of various circuit functions in a very small area. The area of fabricated LUFETs is between 0.1 and 0.3 mm2, and the operating frequency bandwidth approaches 20 GHz. The LUFET mitigates the size and complexity problems considerably and expands the application of combiners and dividers to various multifunction microwave monolithic integrated circuits (MMICs) 相似文献
107.
One of the primary candidates for the liner/etch stop layer in damascene process is silicon nitride (Si3N4). However, silicon nitride has a high dielectric constant of 7.0. To reduce the effective dielectric constant in Copper (Cu) damascene structure, dielectric SiC:H (prepared by plasma enhanced chemical vapor deposition (PECVD) using trimethylsilane source) as the Cu diffusion barrier was studied. The dielectric constant of SiC:H used is 4.2. A systematic study was made on the properties of liner material and electro-chemically plated (ECP) Cu to enhance the adhesion strength in Cu/low-dielectric constant (k) multilevel interconnects. Though the effects of as Si3N4 the liner have been much studied in the past, less is known about the relation between adhesion strength of ECP Cu layer and physical vapor deposited (PVD) Cu seeds, with seed thickness below 1000 Å. The annealing of Cu seed layer was carried out at 200 °C in N2 ambient for 30 min was carried out to study the impact on adhesion strength and the microstructure evolution on the adhesion between ECP Cu and its barrier layer. In the study, our claim that SiC:H barrier/etch stop layer is essential for replacing conventional Si3N4 layer in enhancing adhesion strength and interfacial bonding between Cu/dielectric interconnects. 相似文献
108.
109.
X.G. Peralta I. Brener W.J. Padilla E.W. Young A.J. Hoffman M.J. Cich R.D. Averitt M.C. Wanke J.B. Wright H.-T. Chen J.F. O’Hara A.J. Taylor J. Waldman W.D. Goodhue J. Li J. Reno 《Metamaterials》2010,4(2-3):83-88
We have designed, fabricated and measured electrically-driven active metamaterials which operate as external modulators for TeraHertz Quantum Cascade Lasers. The modulation is achieved by applying a voltage to the metamaterial layer which actively displaces carriers from the n-doped layer causing changes in damping and frequency location of the lowest metamaterial response. We demonstrate their operation at 2.4 and 2.8 TeraHertz and obtain a maximum modulation depth of ~60% with a large degree of modulation linearity. 相似文献
110.
Nanoparticles were prepared by the thermosensitive aggregation of the elastin model polypeptide, (GVGVP)251, and gamma-ray crosslinking. Three different heating processes, “slow heating,” “fast heating,” and “heat shock,” were used
for the aggregation of the peptide, followed by gamma-ray crosslinking. Only the “heat shock” process successfully yielded
stable nanoparticles with diameters of less than ca. 150 nm and a narrow size distribution. Circular dichroism (CD) spectrometry
showed that this polypeptide formed a type-II β-turn structure when the temperature was increased to above the cloudy point
in the case of the “heat shock” process; suggesting that this structure might contribute to stable nanoparticle formation
by gamma-rays. CD spectrometry also suggested that this structure would be affected during the formation of stable crosslinked
particles. 相似文献