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101.
The effects of adding A–B diblock copolymer to a polymer blend (A/B) on phase‐separation kinetics and morphology have been investigated in a fixed shallow‐quench condition (ΔT = 1.5 °C) by in situ time‐resolved light scattering and phase‐contrast optical microscopy. A shear‐quench technique was used in this study instead of a conventional temperature‐quench method. Mixtures of nearly monodisperse low relative‐molecular masses of polybutadiene (Mw = 2.8 kg/mol), polystyrene (Mw = 2.6 kg/mol), and a near‐symmetric butadiene–styrene diblock copolymer (Mw = 6.3 kg/mol) as an interfacial modifier were studied. We observed that the addition of the diblock copolymer could either retard or accelerate the phase‐separation kinetics depending on the concentration of the diblock copolymer in the homopolymer blends. In contrast to the conventional temperature quench, we observed complex phase‐separation kinetics in the intermediate and late stages of phase separation by the shear‐quench technique. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 819–830, 2001 相似文献
102.
Passivation treatment on indium-doped Hg0.8Cd0.2Te epitaxial layers grown on p-Cd0.96Zn0.04Te substrates by molecular beam epitaxy has been performed in order to improve the surface stability of the Hg0.8Cd0.2Te layers. Room-temperature capacitance–voltage measurements clearly revealed metal-insulator–semiconductor (MIS) behavior for the Al/ZnS/passivated Hg0.8Cd0.2Te layer/Cd0.96Zn0.04Te diodes. The fast state density and the fixed charge density of the Al/ZnS/passivated Hg0.8Cd0.2Te/Cd0.96Zn0.04Te diode with a sulfur-treated Hg0.8Cd0.2Te layer were smaller than those with a chemically oxidized Hg0.8Cd0.2Te layer. The interface state density at the ZnS/sulfur-treated Hg0.8Cd0.2Te interface were low at 1011 eV−1 cm−2 at the middle of the Hg0.8Cd0.2Te energy gap. These results indicate that the Hg0.8Cd0.2Te epilayer is significantly passivated by sulfur treatment and that the passivated Hg0.8Cd0.2Te layers can be used for Hg1−xCdxTe-based MIS diodes and MIS field-effect transistors. 相似文献
103.
Soon Moon Park Seung Ho Jeon Taikyue Ree 《Journal of polymer science. Part A, Polymer chemistry》1989,27(12):4109-4117
Interpolymer complex formation between poly(L -proline) (PLP) with helical structure and poly(methacrylic acid) (PMAA) with random-coil structure through hydrogen bonding in aqueous medium has been studied by several experimental techniques, e.g., viscometry, turbidimetry, potentiometry, conductometry, scanning electron microscopy, and x-ray diffraction methods. The decreases in reduced viscosity of the solution on addition of an increasing quantity of PLP to a constant amount of PMAA reveals the formation of a complex between PLP and PMAA. The minimum in reduced viscosity at a unit-mole ratio [PLP]/[PMAA] = 1.0 suggests a 1 : 1 complex formation. A distinct change in the curves for turbidity, pH, and conductance versus [PLP]/[PMAA] supports this conclusion. A scanning electron micrograph for the 1 : 1 PLP–PMAA complexes shows that the PLP/PMAA complex has the shape of entangled long fibers. An x-ray diffraction pattern for the PLP/PMAA complexes gives no diffraction patterns which appear in pure PLP, indicating the destruction of the helical structure of PLP due to the interpolymer complexation. Mixtures of PMAA with poly(γ-hydroxy-L -proline) (PHLP) which has a similar conformation as PLP, but involves intra- or intermolecular hydrogen bonds, has also been investigated by vicometry measurements. The reduced viscosity of a solution of the mixed polymers increases with increasing [PHLP], indicating no complex formation. All the results reveal that the magnitude and the nature of the forces acting in the polymers play an important role in interpolymer complexation. 相似文献
104.
Sul Lee Sunho Jeong Dongjo Kim Sookhyun Hwang Minhyon Jeon Jooho Moon 《Superlattices and Microstructures》2008
Nanocrystalline zinc oxide (ZnO) particles with controlled shapes and sizes were prepared at 180 °C by a simple polyol method. The amount of water and the method of addition played an important role in determining the characteristics of the synthesized particles. Rod-shaped ZnO particles with major axis lengths of ∼114 nm were obtained by heating the precursor solution, while equiaxial particles with average diameters of ∼24 nm were prepared by injecting water into hot precursor solution. Increasing the amount of water added to the precursor solution enlarged the aspect ratio of the rod-shaped particles and increased the particle size of the equiaxial particles due to enhanced hydrolysis and condensation of the Zn ion complex. 相似文献
105.
Yong-Weon Jeon Young-Hyun Jun Suki Kim 《Electronics letters》2000,36(11):940-942
A new column redundancy scheme is presented that can minimise the die area overhead by repair circuits and also achieve fast access speed in high density dynamic random access memories (DRAMs) with wide data widths. The proposed scheme has a large redundancy-area-unit (RAU) which operates a flexible column redundancy scheme that consecutively shifts RDQ (redundant I/O) to neighbouring MDQ (main I/O) without any speed penalty. By using the proposed mapping fuse algorithm. The number of fuses required to store the fail bit address can be reduced, and the chip area reduced. 相似文献
106.
Data integration into the existing cellular voice systems is an attractive approach since it can reduce an initial implementation cost of the data network and can provide voice/data integrated services. In this paper, we propose a data transmission scheme for code-division multiple-access (CDMA) cellular voice systems. The CDMA systems under consideration include IS-95 digital cellular systems using the 800-900-MHz band and J-STD-008 personal communications systems using the 1.8-2.0-GHz band. The proposed protocol and control schemes are designed for real systems based on IS-95 rather than conceptual systems and require no modifications to the existing voice mobile stations (MSs). Using computer simulation, the performance of voice and data users is evaluated. As a result, we show that the proposed scheme well meets our design goals, which are that the data transmission scheme should not only provide a good data performance, but also have little effect on the voice performance 相似文献
107.
M.K. Kim J. Baik C. Jeon I. Song J.H. Nam H.-N. Hwang C.C. Hwang S.H. Woo C.-Y. Park J.R. Ahn 《Surface science》2010,604(19-20):1598-1602
A peptide reaction of glycine on an amine-terminated Si(100) surface was investigated using C 1s, N 1s, O 1s, and Si 2p core-level spectroscopy, where the amine-terminated Si(100) surface was prepared using NH3. In-situ thermal treatments at a mild temperature of 50 °C after the adsorption of glycine on a room-temperature amine-terminated Si(100) surface induced the peptide reaction between the carboxyl group of glycine and the amine group of the surface. This suggests that the amine-terminated Si(100) surface can be an excellent template for constructing a junction between a biomaterial and a Si surface using a dry process. 相似文献
108.
Widely publicized reports of fresh MBAs getting multiple job offers with six-figure annual salaries leave a long-lasting general impression about the high quality of selected business schools. While such spectacular achievement in job placement rightly deserves recognition, one should not lose sight of the resources expended in order to accomplish this result. In this study, we employ a measure of Pareto-Koopmans global efficiency to evaluate the efficiency levels of the MBA programs in Business Week’s top-rated list. We compute input- and output-oriented radial and non-radial efficiency measures for comparison. Among three tier groups, the schools from a higher tier group on average are more efficient than those from lower tiers, although variations in efficiency levels do occur within the same tier, which exist over different measures of efficiency. 相似文献
109.
Wha Sook Jeon Dong Geon Jeong 《Communications Letters, IEEE》2000,4(2):46-48
This paper suggests a NAK-based selective repeat (SR) scheme for reliable data transmission in the future land-mobile communications systems supporting multimedia services. The proposed scheme is an improved version of the automatic repeat request defined in IS-707. We analyze the proposed SR under the assumption of a two-states Markov channel. The numerical results show that drastic performance improvement can be achieved at the cost of minor increase in complexity 相似文献
110.
Jong Hun Kim Kyosun Kim Seok Hee Jeon Jong Tae Park 《Microelectronics Reliability》2005,45(9-11):1455
This paper describes a mechanism of failures in W-plug vias due to the keyhole generation, and presents the process conditions which enhance the reliability of W-plug vias. For a high aspect ratio via-hole, one of the limiting factors in the reliability of the W-plug is the generation of the keyholes. We have investigated the sensitivities of corresponding technologies and conditions to the generation of the keyholes during the plug process. They include deposition technologies of TiN and deposition conditions of W. Based on the SEM observation and the electromigration failure test, the process conditions of TiN and W have been optimized. 相似文献