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91.
Pure hydrogenated amorphous carbon (α-C:H) and nitrogen doped hydrogenated amorphous carbon (α-C:H:N) thin films were prepared using end-Hall (EH) ion beam deposition with a beam energy ranging from 24 eV to 48 eV. The composition, microstructure and mechanical properties of the films were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning probe microscopy (SPM), and nano-scratch tests. The films are uniform and smooth with root mean square roughness values of 0.5-0.8 nm for α-C:H and 0.35 nm for α-C:H:N films. When the ion energy was increased from 24 eV to 48 eV, the fraction of sp3 bonding in the α-C:H films increased from 36% to 55%, the hardness increased from 8 GPa to 12.5 GPa, and the Young's modulus increased from 100 GPa to 130 GPa. In the α-C:H:N films, N/C atomic ratio, the hardness and Young's modulus of the α-C:H:N films are, 0.087, 15 and 145 GPa, respectively. The results indicate that both higher ion energy and a small amount of N doping improve the mechanical properties of the films. The results have demonstrated that smooth and uniform α-C:H and α-C:H:N films with large area and reasonably high hardness and Young's modulus can be synthesized by EH ion source. 相似文献
92.
The steady-shear viscosity, dynamic viscoelasticity, and sedimentation behavior were measured for silica suspensions dispersed
in aqueous solutions of poly(ethylene oxide) (PEO). For suspensions prepared with polymer solutions in which the transient
network is developed by entanglements, the viscosity at a given shear rate decreases, shows a minimum, and then increases
with increasing particle concentration. Because the suspensions are sterically stabilized under the conditions where the particle
surfaces are fully covered with by a thick layer of adsorbed polymer, the viscosity decrease can be attributed to the reduction
of network density in solution. But under the low coverage conditions, the particles are flocculated by bridging and this
leads to a viscosity increase with shear-thinning profiles. The polymer chains with high molecular weights form flexible bridges
between particles. The stress-dependent curve of storage modulus measured by a stress amplitude sweep shows an increase prior
to a drastic drop due to structural breakdown. The increase in elastic responses may arise from the restoring forces of extended
bridges with high deformability. The effect of PEO on the rheological behavior of silica suspensions can be explained by a
combination of concentration reduction of polymer in solution and flocculation by bridging. 相似文献
93.
Keitaro Tanoi Natsuko I. Kobayashi Takayuki Saito Naoko Iwata Atsushi Hirose Yoshimi Ohmae Ren Iwata Hisashi Suzuki Tomoko M. Nakanishi 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):749-751
The time course of Mg uptake and release using intact rice plants and 28Mg as a tracer is presented. Since there is no conventional Mg tracer available, 28Mg was produced via 27Al(α, 3p)28Mg reaction using a cyclotron. Using the purified 28Mg tracer, it was found that the uptake amount of 28Mg by the rice plants increased linearly during 30 min of application. After 28Mg treatment for 90 min, the roots were sequentially washed with iced solution for 120 min. Within about 10 min, almost all of the 28Mg, that was thought to be weakly bound to the apoplast, was washed away. 相似文献
94.
Hidekazu Kumano Satoshi Kimura Michiaki Endo Ikuo Suemune Hirotaka Sasakura Satoru Adachi Shunichi Muto Hai Zhi Song Shinichi Hirose Tatsuya Usuki 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):144
Triggered single-photon generation from InAlAs quantum dot (QD) was demonstrated for the first time. Emitted photon energy coincides with high detection efficiency range of Si single-photon detectors, which is highly suitable for free-space communication. Single-QD spectroscopy and crossed photon correlation measurements unambiguously revealed that several emitting lines observed in a single mesa structure originated from the identical QD, and two temporary competing decay processes associated with neutral states and charged states were identified. Presence of the competing process is also inferred from an analysis of steady-state photoluminescence intensities. Formation process of charged exciton in QD is also discussed. 相似文献
95.
Kenji Hirose Nobuhiko Kobayashi 《Physica E: Low-dimensional Systems and Nanostructures》2005,29(3-4):515
Using the recursion-transfer-matrix (RTM) method combined with nonequilibrium Green's function (NEGF) method, we study the electronic states and current–voltage (I–V) characteristics of junction systems with atomic-scale nanocontacts as a function of the distance between electrodes. We observe a strong nonlinear behavior in the I–V characteristics and correspondingly a gap structure appears in conductance. We find that such a nonlinear behavior emerges when the transport properties change from tunneling to ballistic regimes. 相似文献
96.
We present an efficient self-consistent method for approaching quantum transport through atomic-scale structures. Using the recursion-transfer-matrix (RTM) method with a separable form of nonlocal pseudopotentials, scattering waves propagating between metallic electrodes through nano-bridged structures are efficiently calculated on the basis of the density-functional formalism. We performed calculations with this method of the conductance of Al atomic wires with various kinds of single atoms mixed at the contact to one electrode. We found that the transport properties are considerably affected by the bonding nature of the atom at the contact. The conductance is largely determined by the atomic species at the contact and does not change much as the length of the atomic wire increases. 相似文献
97.
The estimation problems for the conventional step-up method (the observed breakdown voltages are not given at all) and the new step-up method (some of the observed breakdown voltages are given) are analyzed when the underlying probability distribution (of breakdown voltage level) is assumed to be gumbel distributions for minima and maxima. The new step-up test method has advantages compared to the conventional method: (1) the confidence intervals of the estimates become smaller and (2) the estimates can be obtained with higher probability. In some case of real step-up breakdown voltage test, a fit of the gumbel distribution to the data case is found to be superior to that of the normal distribution, which suggests the usefulness of the gumbel distribution for the underlying distribution in the step-up breakdown voltage test. 相似文献
98.
Yoshinori Kamiya Yasutoshi Naito Takuji Hirose Keishin Mizoguchi 《Journal of Polymer Science.Polymer Physics》1990,28(8):1297-1308
Sorption of N2, O2, Ar, CH4, CO2, C2H4, and C2H6 in poly (dimethyl siloxane) liquid and rubber and the dilation of the polymers due to sorption of the gases are studied at 25°C under pressures up to 50 atm. In the liquid, the sorption isotherms for low-solubility and high-solubility gases are described by Henry's law and the Flory–Huggins equation, respectively. Gas sorption in the rubber, which contains a 29 wt % silica filler, follows the dual-mode sorption model, though marked hysteresis is observed in the sorption of O2 and CH4. The dilation isotherms increase linearly or exponentially in both polymers with increasing pressure. Considering that gas molecules adsorbed into micropores of the filler particles do not participate in the dilation, partial molar volumes of the dissolved gases in the rubber are determined from data of sorption and dilation. The values are nearly equal to the partial molar volumes in the liquid (48–60 cm3/mol). 相似文献
99.
Two factors were separated from rat liver particulate fraction treated with insulin, one of them having a stimulating effect on low-Km adenosine 3',5' cyclic monophosphate (cAMP) phosphodiesterase activity of crude microsomal fraction (P-2 fraction) and the other having an inhibiting effect on the activity of low-Km cAMP phosphodiesterase solubilized with 0.3% Brij 58 from P-2 fraction. Trypsin and heat treatments had essentially no effect on these two factors. The stimulating factor did not significantly change the apparent Km value of enzyme in P-2 fraction but increased the maximal velocity of the reaction. The inhibiting factor raised the Km value of solubilized enzyme without affecting the maximal velocity of the reaction. The stimulating factor level in diabetic rat was larger than that in normal rat while the inhibiting factor level in diabetic rat was smaller than that in normal rat. Possible participation of both factors in insulin action is discussed. 相似文献
100.
Investigation on the Surface‐Confined Self‐Assembly Stabilized by Hydrogen Bonds of Urea and Amide Groups: Quantitative Analysis of Concentration Dependence of Surface Coverage
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Formation of a hydrogen‐bond network via an amide group is a key driving force for the nucleation–elongation‐type self‐assembly that is often seen in biomolecules and artificial supramolecular assemblies. In this work, rod‐coil‐like aromatic compounds bearing an amide ( 1 a – 3 a ) or urea group ( 1 u – 3 u ) were synthesized, and their self‐assemblies on a 2‐D surface were investigated by scanning tunneling microscopy (STM). According to the quantitative analysis of the concentration dependence of the surface coverage, it was revealed that the strength of the hydrogen bond (i.e., amide or urea) and the number of non‐hydrogen atoms in a molecular component (i.e., size of core and length of alkyl side chain) play a primary role in determining the stabilization energy during nucleation and elongation processes of molecular ordering on the HOPG surface. 相似文献