So far, the diffusion phenomena in a gas centrifuge has been analyzed solving the governing equations by analytical approximation methods, or by numerical calculation with the finite difference method (FDM). In the present paper, a numerical procedure using the finite element method (FEM) is presented for the estimation of concentration distribution in a gas centrifuge.
First, a variational form is shown for the convection-diffusion equation and its boundary conditions including concentration-, pressure- and thermal-diffusions.
Next, boundary conditions are discussed especially for the ports for feed, product and waste, and accordingly we clarify a necessary condition for boundary conditions adopted in the previous analysis by FDM.
Furthermore, an arbitrary pattern of the internal flow can be expressed by introducing the stream function so that the mass balance in each element is strictly attained.
Computations are made on various types of gas centrifuges by assuming a simple flow pattern. The results of the present method are compared with the FDM proposed by T. Kai and provide a good agreement.

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The amounts of fine coal included in the raw coal to be washed have been, increased by reason of the adoption of mechanical coal mining method in Japan. On the one hand the demands of fine coal have been increased rapidly in the cause of the increase of the electrical power station used the low-grade coal. Therefore, it is the important problem that fine coal is recovered effectively in the coal preparation plant.
The various equipments to be.treated fine coal are classified by their use as follows:(1) separator (flotator and washing table), (2) thickener and classifier (boot of bucket elevator, Bacher tank, settling cone, thickener, wet cyclone and settling tank)(3) dewatering machine (fixed screen, vibrating screen, filter and centrifuge), (4) settling pond.
Many systems of the treatment of fine coal consist of the simple or complicated combination of the aforementioned equipments in the coal preparation plant, but the character of modern system of the treatment of fine coal includes one of the following equipments, that is, flotator, thickener, filter and centrifuge.
Both of flotation and centrifuge have been developed remarkably and adopted in our country. In this paper, therfore, the domestic status of flotation are described, on the one hand the various centrifuges are classified by their constructions and their characteristics are explained respectively.

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The conventional methods for the examination of the osmotic fragility of erythrocytes have inherent disadvantages of poor reproducibility, requirement of a large amount of blood sample and time-cosuming procedure.
Coil planet centrifuge method presented here gave a high reproducibility with a minute amount (1∼3 μl) of blood and required a relatively simple technique.
According to this method, erythrocytes were forced to travel through a long linear density gradient in a fine vinyl tube from physiological saline solution to hypotonic solution at a constant speed. So the erythrocytes were exposed to a gradually decreasing osmotic pressure down to the point where hemolysis occurred, thus the hemoglobin distribution pattern, in other words, the erythrocyte osmotic resistance curve, was observed.
The erythrocytes osmotic resistance curve obtained by our method showed some clinical informations which could not be obtained by the conventional methods.

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ニワトリ精液の洗浄濃縮に有効な密度勾配法の検討を目的として,遠心用担体にPercollを用いて試験した。精液評価は活力,奇形率,精子回収率及び受精率によって行ない,それぞれ前•後の性状変化を観察した。そして次のような結果が得られた。
(1) 多層のPercoll密度勾配でしたところ,精子は密度1.07と1.08の層に集中した。
(2) 2層のPercoll密度勾配で後の精子性状を比較したところ,活力及び奇形率に対しての影響は見られなかった。また精子回収率は平均92.6%であった。
(3) (2)と同様に,受精率について比較したところ,精子数3.4×10⁸あるいは0.9×10⁸のどちらを注入した場合でも,人工授精後,1週間日,2週間日の受精成績にの影響は見られなかった。
以上のことからPercollを用いた密度勾配法は,ニワトリ精液の洗浄•濃縮に応用可能であると思われた。

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　我が国のウラン濃縮施設のうち核燃料サイクル開発機構 人形峠環境技術センターでは、ウラン濃縮の技術開発を終了し、廃止措置の検討が行われる一方で、日本原燃(_(株)_)六ヶ所商業プラントにおいても既設機への更新が計画されている。これらに伴って発生する多数の使用済み機は、放射性廃棄物低減化及び資源の有効利用を図りながら適切に処理・処分することが望まれる。　放射性廃棄物の大幅な低減を目指して、ＤＰ機を用いた除染試験を実施した。機には、長期間、六フッ化ウランガスと接することにより部品表層にウラン化合物が付着或いは浸透している。このウラン化合物を取り除くため、機の主要部品について、希硫酸（5wt%）による化学除染を行った結果、ウラン濃度は、0.1Bq/g程度まで低下した。

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塗料の製造を対象とした範囲の酸化チタン顔料の懸濁液について, 顔料粒子の径が5μ以上のものを除去することによる粒度管理および能率向上の目的で遠心力による分級を行なった。
適当な条件の酸化チタン顔料の懸濁液を使用することにより, 得られる分級結果は理論的計算値とほぼ一致することが認められた。適当な懸濁液の条件は, 分散媒の粘度が低く, 懸濁液のもつ構造粘性の程度が少なく, 構造粘性の回復の時間が長いことである。このような系に対しては, 円筒コンベヤ形機は適しているものの一つであり, 沈降粒子は自動的に機外に除去することができる。

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We observed in vitro experiment that lead increased osmotic resistance of normal human erythrocytes and decreased mean corpuscular volume and intracellular potassium. Though the mechanism of the increased osmotic resistance of erythrocytes caused by lead has not yet been completely clarified, the following hypothesis could be accepted. Lead cause leakage of water from erythrocytes, which means that more water can enter the cell before hemolysis occurs. But, there has been no report of direct measurement of the intracellular water content of of erythrocytes treated with lead. This paper tried to clarify the relationship between intracellular water and osmotic resistance of lead treated erythrocytes in vitro experiment. The results were: 0.05 μmol/ml of lead increases osmotic resistance, trapped water content and plasma water content of normal human blood and decreases intracellular water content after incubation for 2 hours at 37°C.

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福島原発事故のために放出された放射性物質により汚染された土壌や海水、災害廃棄物などの除染が問題となっている。放射性セシウム濃度が8,000Bq/kg以下であれば、一般廃棄物最終処分場に埋立可能である。そのため焼却残渣からのセシウム溶出特性を把握し、より効率的にセシウムを回収することができれば、一般廃棄物として埋立可能となり、効果的に除染を行える。本研究では、放射性セシウムに汚染された災害廃棄物の焼却により発生する焼却残渣の減容化および除染の高効率化を目的とした。放射性セシウムを含んだ飛灰（6431Bq/kg)を対象に、大型機を用いたセシウムの溶出特性の調査、溶出量試験（JIS K 0058-1）との比較、実験結果の妥当性の検討を行った。結果、溶出量試験に比べて試験の方が高濃度のセシウム含有溶液を抽出できることが示唆された。また、今回の実験結果の妥当性を示すことができた。

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With a view to ensuring more logical application to the cascade theory of centrifuges, the separative factor N'(1-N)/N(1-N'), currently adopted in such studies, is replaced by a "separative coefficient", defined by α=N'/N (N being the mole fraction of ²³⁵U). Using this coefficient, equations expressing the distributions of flow and of isotope concentration are obtained from the material balance relations. Several other equations, applicable to the ideal cascade, giving the separative power and expressing the value function are also derived.
These equations are then utilized in the consideration of control problems, such as the influence of loss and cut, and the treatment of reflux and of product withdrawal from stages other than the top. Simulation of an actual cascade for uranium isotope separation by centrifugation is undertaken with use made of the Monte Carlo method, assuming that losses, cuts, separative coefficients and the feed flow are normally distributed with certain mean values and variances. he mean values of the separative coefficients are assumed to satisfy the equations for a single centrifuge (separative coefficients being functions of flow). The influence of fluctuations in time is taken into account.
The analysis proves that provided the separating units work as prescribed by theory, operation of the centrifuge cascade should not be difficult, since no necessity is indicated for strict control, while at the same time product concentration could be adjusted to a certain extent, and moreover the cascade would not be sensitively affected by losses.

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