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61.
62.
Rubber components of production equipment are a significant source of contamination in the fabrication of VLSI devices and other semiconductor products. One approach to solving this problem is to use a magnetic levitation system for noncontact transfer. The force nonlinearity of magnetic circuits presents a problem, particularly when the gap between the magnets and the levitated vehicle is small. Linearization methods that allow effective control do exist, but in this paper an alternative method not based on linearization is proposed. The design involves magnetic levitation control by 4-point attraction. The experimental results indicate that the idea is an effective one. 相似文献
63.
K Shimizu S Ohtani H Shiono T Fukusima M Sasaki 《Canadian Metallurgical Quarterly》1997,86(1-2):61-68
To isolate DNA for nucleoside analog incorporation studies, many investigators use RNase A to remove RNA from total cellular nucleic acid. We observed persistence of ribonucleotides from RNA in nucleic acid samples treated with RNase A alone. Although incubation of [5-3H]uridine-labeled nucleic acid with 50 microg/ml RNase A decreased tritium by 97%, HPLC analysis of the resulting DNA preparation digested to nucleosides revealed high levels of ribonucleosides. Increasing RNase A 10-fold (500 microg/ml) effected only a 1.7-fold reduction in ribonucleosides. Overall, the level of ribonucleosides was one-fourth that of the deoxynucleosides, primarily due to the high levels of guanosine. It was hypothesized that the ribonucleosides originated from guanosine-rich tracts of RNA since RNase A cuts preferentially 3' to pyrimidine monophosphates and to some extent after AMP. The addition of 0.05 microg/ml RNase T1, which preferentially cleaves RNA 3' to GMP, decreased total ribonucleosides by nearly 20-fold. In conclusion, we have developed a rapid method which removes greater then 99% of cellular RNA from nucleic acid extracts and a reversed-phase HPLC procedure that detects RNA contamination more sensitively than [5-3H]uridine labeling. These methods are useful for the determination of analog incorporation into DNA, especially for agents which incorporate into both DNA and RNA. 相似文献
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66.
Masakazu Katsuno Noboru Ohtani Tatsuo Fujimoto Hirokatsu Yashiro 《Journal of Electronic Materials》2005,34(1):91-95
The effect of off-orientation growth has been investigated in terms of stacking fault formation during physical vapor transport
(PVT) growth of silicon carbide (SiC) single crystals on the (11
0) seed crystal surface. Occurrence of stacking fault formation is largely dependent on the direction of off-orientation,
and basal plane stacking fault density is significantly reduced by growing the crystals on a (11
0) seed crystal off-oriented toward 〈0001〉. The density of the basal plane stacking faults rapidly decreases from 100–150
cm−1 to ∼10 cm−1 as the degree of off-orientation is increased from 0 to 10 deg. The results are interpreted in the framework of microscopic
facet formation during PVT growth, and the introduction of off-orientation of seed crystal is assumed to prevent (01
0) and (10
0) microfacet formation on the (11
0) growing surface through modification of the surface growth kinetics and to suppress the stacking fault formation.
An erratum to this article is available at . 相似文献
67.
Heat generated during dynamic crack propagation in viscoelastic solids was investigated by visible liquid crystal film technique to observe the thermal boundary front emanating from a running crack tip. The crack propagation velocity was also measured by the velocity gauge method. The heat so estimated is correlated with the crack propagation velocity. 相似文献
68.
The temperature dependence of resistivities of gas sensors made of SnO2, Pd-doped SnO2, and ThO2-doped SnO2 with Pd has been investigated in air containing reducing gases such as CO, H2, and C3H8. The curves for ThO2-doped sensors were significantly influenced by the reducing gases as compared to the sensors without ThO2. From these results, it is found that in Pd-doped SnO2 sensors the dopant plays an important role in oxidizing the surface of SnO2 above 170°C, and that the addition of ThO2 to Pd-doped SnO2 enhances the effects of Pd by removing the adsorbed hydroxyl on SnO2. It is also apparent that the interactions between reducing gases in air and SnO2-based sensors depend upon the oxidizing rates of the surface of SnO2, as well as the amounts of the adsorbed hydroxyl on SnO2. 相似文献
69.
The rheology of polystyrene powder beds was examined by two kinds of experiments. From stress relaxation measurements during powder compaction, it was found that relaxation at the shorter times could be attributed to sliding between particles. This is followed by a relaxation attributed to the deformation of the polystyrene particles themselves. From dynamic mechanical measurements, an increase was found in the value of vibrational absorption coefficient (Q?1 value) at a temperature below that of the main relaxation dispersion of bulk polystyrene, attributed to the slipping around tight particle junctions. These phenomena appear characteristic of powder-like materials. 相似文献
70.