An experimental study on the effects of operational conditions on the formation of ultra fine powders was carried out by a reciprocating friction mill with marble as the specimen. The effects of the working speed, the working pressure and the contact area on the production rate of powder were investigated and the following results were obtained.
(1) The effects of the working speed and the working pressure were not significant for the particle size of the powders produced by this mutual friction and abrasion method. The mean particle size was almost constant around the size of 0.2∼0.3μ.
(2) The production rate of powder was greater when the contact area of specimens was smaller.
(3) It seems that the mechanism of abrasion of marble has analogy with the wearing mechanism of metals in consideration of the relation between the mass of produced powder and the working speed. The details have to be experimentally studied from the mechano-chemical point of view.
(4) The mass of the produced powder varied with the working speed and the working pressure when the contact area was constant, and the maximum mass was obtained at the speed of about 6cm/sec and the pressure of 1.5Kg/cm² in this experiment.
(5) Between the production rate of powder Q and the working pressure P, the relation of Q=cPⁿ was obtained. From the correlation of the index n and the working speed, it seems possible to conjecture the dependence of abrasion mechanisms on the working speed.

抄録全体を表示

新しいペネム系経口抗生物質, ritipenem acoxil (RIPM-AC) について以下の知見を得た。
1.ヒト前立腺液への移行性
本剤400mg投与後1時間の前立線液内のritipenem (活性本体) 濃度は被験した4検体いずれも0.08μg/ml以下 (検出限界) であった。
2.尿路感染症の臨床成績
複雑性尿路感染症のうちUTI基準に合致した17例での効果判定では, 著効11例, 有効4例, 無効2例で総合有効率は88.2%であった。細菌学的効果は除菌率が26株中23株, 88.5%であった。副作用としては胃部不快感が1例で認められた。臨床検査値の異常変動は全例で認められなかった。

抄録全体を表示

モルモットを用いて, 化学物質の光感作性を検討していたところ, 光感作誘発の段階で化学物質を塗布していない部位にUVA照射 (10.2J/cm²) のみで紅斑を示す動物を認めた。これらの動物は数ケ月から1年後においてもUVA照射のみで紅斑反応を示し, UVBに対するMEDの低下を見た。
PLR発生原因追求の結果, 光感作誘導時のFCA (アジュバント) とUVA照射量が主因であり, 化学物質ベンゾカイン (局所麻酔薬) は増強因子として働いていることがわかった。この結果から, FCA 1.2ml, UVA 20.4 J/cm², ベンゾカイン5%エタノールの条件で光感作誘導をかければ高頻度の割合でPLR動物を作製することができた。

抄録全体を表示

An experimental study on the effect of surface roughness on the formation of ultra fine powders was carried out by a rotating friction mill devised to produce submicron powders by mutual friction grinding of two specimens of marble. The following results were obtained.
(1) The surface roughness of the specimen decreased with particle size of carborundums used for final finish of the specimen surface. The specimen surface changed to take a different roughness or undulation just after abrasion, but it reached a constant roughness or undulation as the abrasion approached to a steady state.
(2) By scanning electron microscopy, it was observed that the specimen surface seemed to be melting and the surface layer changed to an amorphous state from a crystalline pre-abrasion state. From the electron diffraction pattern, the similar result was obtained on the surface layer of the produced powder.
(3) The particle size of the produced powder decreased with the surface roughness of specimen. The reason is considered that the cohesion area is smaller when the surface roughness is smaller.
(4) The mass of the produced powder increased as the surface roughness decreased. This tendency arises from the fact that the number of contact point and contact area of the tiny surface protuberance is closely related with surface roughness. It is concluded that the surface roughness of the specimen is an extremely important factor in mutual friction grinding.

抄録全体を表示

A test mill of rotating disc type was devised to make clear the grinding mechanism in an attrition-and-friction mill. The friction force and the surface roughness of the friction surface were measured, and the production rate and the size distribution of fine particles with respect to load, sliding velocity, and sliding distance were investigated in relation with them. The inorganic matrials such as dolomite earthernware and chalk were used. The experimental variables and ranges were as follows: load; 1.04-23.2N, sliding velocity; 0.22-2.1m/sec.
The following experimental results are obtained:
1) The kinetic friction coefficient μk is increased in a small degree with the increase of applied load, but it is independent of the sliding velocity Furthermore, the fluctuation of friction force has a close relation with the production rate of fine Particles.
2) From the observation of scanning electron micrographs, the fracture surface of brittle fracture is confirmed in the friction surface.
3) The applied load has more significant influence on the average surface roughness of the friction surface than other factors such as sliding velocity and sliding distance.
4) The relationship between the production rate of fine particles Q and the value of PV can be formulated as follows:
Q=k₁(PV)
where the constant k₁ is considered to be an index for easiness of grinding of material, and its value is 0.31mg/J for dolomite earthenware and 0.9mg/J for chalk.
5) The median particle size measured with the electron microscope is about 0.7±0.1μm for dolomite earthenware, and the shape' of particles is an ellipsoid of which the ratio of major radius to minor radius is 1.9.
6) The grinding energy applied to unit volume of produced fine particles and specific fracture-suface energy for dolomite earthenware are estimated to be 2.19±0.39×10³MJ/m³, 200J/m², respectively.

抄録全体を表示

An experimental study on the production of fine powders was carried out by an agitating mill devised to produce ultra-fine powders by the mutual friction of sample powders of gypsum. The following results were obtained:
(1) Powders of micron order could definitely be produced by this method and there was only a few percent of submicron powders produced, but it was proved that the production of ultra-fine powders was possible by this method.
(2) The size distribution curves of the produced powders shifted toward smaller particle size with grinding time and the rotating velocity.
(3) The relationship between the specific surface area produced and grinding energy conformed to the final finness limit theory proposed by T. Tanaka.
(4) The specific surface area produced increased with the rotating velocity of the impeller and finally approached a constant value.
(5) When the rotating velocity of the impeller was under 3620 1/min, the specific surface area produced was scarcely affected by the mass of fed sample powders, but at over 4800 1/min it increased as the mass increased.
(6) The specific surface area produced increased with the ratio of the fed sample volume to the agitating vessel volume and finally approached a constant value.
(7) The relationship between the specific surface area produced and various factors was obtained by dimensional analysis.

抄録全体を表示

平塚市民病院において1992年と1993年の2年間に, 入院患者より分離されたmethicillin-resistant Stapkylococcus aureus (MRSA) について疫学的検討をしたので, その成績を検討する.
被検体は各科領域で入院中に分離された起炎菌と思われる株を30株ずつ選択して用いた.1992年と1993年との比較をすると, 抗生剤に対する感受性試験では, MINOとIPMのMIC80が3-13μg/mlから25μg/ml, 25μg/mlから200μg/mlと著明に低下した.また, VCMやABKなどMRSAに有用とされている薬剤も1～2管抗菌活性の低下がみられた.コアグラーゼ型別では, 1993年には全部II型に変化した.エンテロトキシン型別では, B/C型のbi-typeが検出される割合が増加した.toxic shock syndrometoxin-1 (TSST-1) 産生能では, 産生株24, 非産生株6から被検体30全株が産生株となった.Plasmid DNA profileは多種の型が見られるようになった.同一株の検出された場所, 時期, 患者の相互関係は殆ど認められなかった.
僅か1年の問に薬剤感受性, トキシン産生能や型別, plasmid DNA profileの著明な変化が認められた結果より, MRSAに対抗すべき抗菌剤には改めて慎重な配慮が必要であることが示唆された.更にその発生には院内感染と表現するより院内汚染といった傾向が伺われ, 予防については再検討する必要があると思われた.

抄録全体を表示