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41.
Y. Nakamura Ichiro Tanaka N. Takeuchi S. Koshiba H. Sakaki 《Journal of Electronic Materials》1998,27(11):1240-1243
We studied morphology of GaAs surfaces and the transport properties of two-dimensional electron gas (2DEG) on vicinal (111)B
planes. Multi-atomic steps (MASs) are found on the vicinal (111)B facet grown by molecular beam epitaxy, which will affect
electron transport on the facet. We also studied how the morphology of GaAs epilayers on vicinal (111)B substrates depends
on growth conditions, especially on the As4 flux. The uniformity of MASs on the substrates have been improved and smooth surfaces were obtained when the GaAs was grown
with high As4 flux, providing step periodicity of 20 nm. The channel resistance of the 2DEG perpendicular to the MASs is reduced drastically
with this smooth morphology. These findings are valuable not only for fabricating quantum devices on the (111)B facets but
also those on the vicinal (111)B substrates. 相似文献
42.
Yukihisa Tanaka Jiro Hirano Tadashi Funada 《Journal of the American Oil Chemists' Society》1992,69(12):1210-1214
In an attempt to concentrate the content of DHA (docosahexaenoic acid) in a glyceride mixture containing triglyceride, diglyceride
and monoglyceride, fish oil was hydrolyzed with six kinds of microbial lipase. After the hydrolysis, free fatty acid was removed
and fatty acid components of the glyceride mixtures were analyzed. When the hydrolysis withCandida cylindracea lipase was 70% complete, the DHA content in the glyceride mixture was three times more than that in the original fish oil.
The EPA (eicosapentaenoic acid) content became almost 70% of the original fish oil. Hydrolysis with other lipases did not
result in an increase in the DHA content in the glyceride mixtures. Hydrolysis of DHA-rich tuna oil (DHA content is about
25%) withCandida cylindracea lipase resulted in 53% DHA in the glyceride mixture. The EPA content, however, remained close to that of the original tuna
oil. In this report, the acyl chain specificity of lipases is evaluated in terms of hydrolysis resistant value (HRV). HRV
is the ratio between the DHA contents in the glyceride mixture of hydrolyzed oil and original oil. HRV clearly indicates differences
in hydrolysis between DHA and other fatty acids (e.g., saturated and monoenoic acids). 相似文献
43.
Ogi H. Nakamura N. Sato K. Hirao M. Uda S. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2003,50(5):553-560
This paper presents advanced techniques to determine all independent elastic-stiffness coefficients C/sub ij/, the associated internal friction Q/sub ij//sup -1/, and piezoelectric coefficients e/sub ij/ of monocrystal langasite (La/sub 3/Ga/sub 5/SiO/sub 14/) using a single rectangular parallelepiped specimen. Langasite's crystal structure belongs to the trigonal system with point group 32, and thus possesses six independent C/sub ij/, two e/sub ij/, and two dielectric coefficients /spl epsiv//sub ij/. All of the elastic and piezoelectric coefficients affect the mechanical resonance frequencies of the solid specimen, and measuring them very accurately permits one to determine the C/sub ij/ and e/sub ij/ with known density, dimensions, and e/sub ij/. We developed a piezoelectric tripod to support the specimen upward and measured the free-vibration resonance frequencies with minimum load from its own weight. This weak and stable acoustic coupling ensures accuracy of the frequency measurement better than 10/sup -5/, enough to determine the coefficients reliably. Our C/sub ij/ fall in the range of results measured with previous (conventional) methods. Our e/sub 11/ is smaller than the reported values by 1.2-13%, and e/sub 14/ is larger by 44-97%. For the internal friction measurement, we used a solenoid coil to vibrate the specimen without any contact. The longitudinal-wave internal friction considerably exceeds the shear-wave internal friction, which can be explained by phonon-phonon interactions. 相似文献
44.
Immunoassay method for the determination of immunoglobulin G using bacterial magnetic particles. 总被引:7,自引:0,他引:7
We have developed a novel immunoassay method using bacterial magnetic particles for the determination of immunoglobulin G (IgG). Fluorescein isothiocyanate (FITC) conjugated anti IgG-bacterial magnetic particles were prepared. The fluorescence quenching caused by agglutination of FITC-anti IgG antibody-bacterial magnetic particle conjugates was measured by using a fluorescence spectrophotometer. The aggregates based on specific immunoreaction were separated by a gelatin solution. The aggregation of bacterial magnetic particle conjugates was enhanced by application of a magnetic field. The relative fluorescence intensity correlated linearly with a concentration of IgG in the range 0.5-100 ng/mL. 相似文献
45.
The Bi2O31bM2O5 films (M=V, Nb and Ta) were prepared by a rapid quenching technique using a twin-roller type equipment. Quenched film of pure Bi2O3 partially precipitated a tetragonal phase which differs from well-known β-Bi2O3 in structure. In every (Bi2O3)0.975 (M2O5)0.025 composition (2.5% M2O5), the tetragonal phase was obtained as single phase, and the tetragonality became greater than that of the pure Bi2O3. Beyond this composition, the tetragonality decreased to form δ-phase with a fcc structure with increasing the M2O5 content. The lowest V2O5 content forming a δ-phase was 5%, while a slight tetragonality still remained in the samples containing 10% Nb2O5 and 10% Ta2O5, respectively. From the measurement of the photoconductivities of the quenched films, it was proved that a photoconduction appeared in the tetragonal phase while no photoconductivity was observed in the cubic phase. The characteristic of the photoconduction was that a remarkable decrease in the resistivity was observed when a light of ca. 500 nm in wave length was irradiated on the films. 相似文献
46.
Mitsuhiro Fukuta Tadashi Yanagisawa Hiroaki Iwata Kazutaka Tada 《International Journal of Refrigeration》2002,25(7)
This paper discusses the feasibility of a vapor compression/absorption hybrid refrigeration cycle for energy saving and utilization of waste heat. The cycle employs propane as a natural refrigerant and a refrigeration oil as an absorbent. A prototype of the cycle is constructed, in which a compressor and an absorption unit are combined in series. The performance of the cycle is examined both theoretically and experimentally. Although the solubility of the propane with the oil is not enough as a working pair in the absorption unit, the theoretical calculation shows that the hybrid cycle has a potential to achieve a higher performance in comparison with a simple vapor compression cycle by using the waste heat. In the experiment, the prototype cycle is operated successfully and it is found that an improvement of an absorber is necessary to achieve the good performance close to the theoretical one. The application of an AHE (absorber heat exchanger) can reduce the heat input to a generator. Further examinations on some other combinations of refrigerant/refrigeration oil and additives are desirable. 相似文献
47.
48.
Frequency-shifted feedback (FSF) laser exhibits outstanding features in its oscillation spectrum. We analyze build-up dynamic properties of the FSF laser by means of rate equation and analyze steady-state dynamic properties of the FSF laser by means of Wigner-Ville distribution of intracavity electric field. Furthermore, we analyze instantaneous oscillation frequency at peak spectral intensity and oscillation bandwidth of its spectrum using the formula of instantaneous spectral intensity derived from Wigner-Ville distribution of intracavity electric field. These analytical results are in good agreement with the experimental ones which have been observed by a diode-pumped Nd:YVO4 FSF laser. It becomes clear that the FSF laser supports many frequency components simultaneously even though the gain medium is homogeneously broadened and has a continuously chirped frequency components of comb in which the creation of chirped frequency components are strongly correlated in phase because of a replica of the preceding components. Also, the instantaneous oscillation frequency is closely related to the detuning frequency which depends on the total net gain in the cavity and the gain bandwidth of atomic transition. The oscillation bandwidth is defined as the product of the saturation-broadened bandwidth and the total resonant modes contributing to FSF operation 相似文献
49.
T Kataoka M Wachi J Nakamura S Gayama M Yamasaki K Nagai 《Canadian Metallurgical Quarterly》1993,194(3):1420-1426
In an in vitro assay, the oriC DNA has been shown to bind to the outer membrane fraction only when it is hemimethylated (G.B. Ogden et al., Cell, 54, 127-135,1988). In this report, however, we demonstrated that a significant amount of the oriC DNA was recovered from the cells just before initiation with the oriC DNA being fully methylated. Formation of this preinitiation oriC-membrane complex and following initiation of chromosome replication were strongly inhibited by novobiocin, a DNA gyrase B subunit inhibitor, which reduced the superhelicity of the reporter plasmid in the cells. On the other hand, both reactions proceeded in the presence of nalidixic acid, a DNA gyrase A subunit inhibitor, which did not have the effect of reducing the superhelicity. These results suggest that the negative superhelicity of the DNA is required for preinitiation oriC-membrane complex formation and following initiation event of replication. 相似文献
50.
T. S. Saitoh M. Nakamura T. Gomi 《International journal for numerical methods in engineering》1994,37(11):1793-1805
In this paper, the time–space method (TSM) for multidimensional melting and solidification problems is proposed. In the proposed TSM, the timewise co-ordinate is incorporated into one of the spatial co-ordinates, thereby transforming the usual transient 2-D (or 3-D) problems into steady 3D (or 4-D) boundary-value problems. Since time integration is not necessary, the TSM has a feature that eliminates the so-called numerical instability which has been a great concern in the principal numerical methodologies in the past. That is, no error propagation in the timewise direction occurs in the TSM calculation. The TSM is applicable to almost all transient heat transfer and flow problems. The computer running time will be reduced to only 1/100th–1/1000th of the existing schemes for 2-D or 3-D problems. The sample calculations are presented for a 2-D melting problem in a square cavity and the validity of the present method is examined. 相似文献