The natural environments of microorganisms are generally composed of two or more phases. Microbial cells themselves are so small that the even distribution of molecules or ions is not fixed owing to thermal fluctuation. A large amount of microorganisms live at air-water, air-solid or water-solid interfaces. It was shown how a variety of microorganisms come to stay on the surfase of river bed stones. Soil is the most important habitat which accommodates a great variety of bacteria, fungi and protozoa. Multiphase microstructure of soil aggregate is considered to be essential to support the lives of these organisms.

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Ultrapure water is used in the final rinse stage of silicon wafer cleaning for ULSI fabrication. Recently, advanced ultrapure water production systems have been developed. They can supply ultrapure water in which any impurities are reduced to an extremely low level. Dissolved oxygen also has been reduced to ppb level for native oxide free processing. Further, Cr₂O₂ stainless steel piping has been also developed for continuous ozone injection sterilization in ultrapure water systems. In addition, it is becoming possible to develop perfectly controlled ultrapure water technolgies such as ozone-added-ultrapure-water rising for the removal of organic from wafer surfaces and boiling-ultrapure-water treatment for the realization of H-terminated wafer surfaces.

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We investigated the characteristics of an air-lift pump system for conveying coarse particles consisting of different sizes and densities. Based on a momentum equation, we proposed a method to correlate discharged flow rates of both particles and water with a supplied air flow rate. To confirm the validity of the proposed correlation, experiments were carried out with an air-lift pump system, whose upriser was a pipe of 40 mmID and 7.86m long. The experimental conditions were as follows: The submergence ratio was 0.8; two sorts of ceramic spheres were used at a time chosen from three whose diameter and density were (6.0mm 2540kg/m³), (9.9mm, 2540kg/m³) and (9.6mm, 3630kg/mm³); the mass flow rate of the mixed particles was set constant at 0.10, 0.20 or 0.30kg/s, respectively. The experimental data is presented, and comparisons between the data and the calculations are made in this report.

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前回「沸騰二相流」その英語句として考えられるboiling two-phase flowなる語が、歴史的に数奇な意味あいを持っていること、また実際この語句が一部のみの調査ではあるが、英文誌にみられないことなどについて述べた。今回はその続きとして沸騰流の分類に関連する基本的語句についてふれる。
沸騰の分類として伝熱工学資料 [1] にはA: 液体温度によりサブクール沸騰と飽和沸騰、B: 液体の流動状況によりプール沸騰と強制対流沸騰の二つの面から分類してある。このほか、C: 沸騰の機構により核沸騰と蒸発、およびD: 沸騰が生じている場の幾何形状により内部沸騰と外部沸騰とに分類することもできる。
以下にはこれらに基づいて記述する。なお沸騰に関する用語は数多いが、ここでは「沸騰二相流」という語句の周辺の用語にとどめる。

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