Abstract. We previously reported that sphingosine 1-phosphate (S1P) induces inhibition of adenylyl cyclase and activation of phospholipase C via independent G protein-coupled receptors in adult rat hepatocytes. Although S1P activation of phospholipase C and subsequent increase of intracellular Ca 2+ concentration were enhanced during the primary culture of hepatocytes, S1P inhibition of adenylyl cyclase remained unchanged. Here, we addressed whether enhancement of S1P-induced actions is dependent on change of status from the differentiated (G 0 ) phase to proliferating (G 1 / S) phase in hepatocytes. By employing cell-density-dependency of the transition (G 0 -G 1 ) of hepatocytes in primary culture in vitro, it was found that the enhancement of phospholipase C activation by S1P was dependent on cell density and correlated to the G 0 -G 1 transition. The correlation was further confirmed in vivo by 70% hepatectomy as a proliferating hepatocytes model. Northern blot analysis suggested an enhanced expression of S1P 2 receptor in proliferating hepatocytes.

Full instrumentation is made on a medium size boring machine to speed up the experiments and to get more precise data. Penetration rate, torque, thrust and pressure of water supply can be recorded automatically on four channel pen-writing oscillograph. All results are of laboratory studies bored into the rock specimens ranging from hard to soft formations. Diamond bit used is a surface setting core bit, 46mm in size, having 12 carat setting. Rotation speed and volume of water supply are variable as parameter. Main results obtained from these experiments are as follows:1) Penetration rate is almost proportional to thrust and rotation speed of bit 2) Relation between thrust and torque is almost constant for all rocks and this relation does not change by rotation speed.3) Max. penetration rate is proportional to volume of water supply in the case of the rotation speed i constant.4) Max. penetration rate is proportional to square root of rotation speed and the max. thrust corresponding to max. penetration rate is inversely proportional to square root of rotation speed. 5) Penetration rate and max. thrust for each rock can be presumed from the shore hardness, indentation depth and compressive strength of the rock.

The metal core bit is widely applied for boring of the softer rocks.This study was made on such important problems for boring as bit shape,cutting mechanism of cutting edge of bit,interrelation between thrust,rotation speed,penetration rate,torque and bit wear and relations between boring conditions and bit wear.The main results obtained are as follows: 1) max.penetration rate was increased about 3 times compare with ordinary bit by improving the bit shape.2) in the case of rotation speed of bit and water supply is constant,relations between thrust(W), penetration rate(V)and torque(T)is W=a Vn,W=a'Tn' in grinding stage and W=w,+mV, W=w'+m'T in cutting stage,and each coefficient of these formula is almost proportional to wearing width of cutting edge of bit.3) in the case of thrust is constant,the penetration rate is proportional to rotation speed of bit,but torque does not change by rotation speed. 4) if consider the bit wear,the effective boring would be done in lower rotation speed and in higher thrust.Also,it was proved that the relation between thrust,torque and penetration rate would be calculated from the data of the cutting resistance,exactly.

No abstract

A rotary bit penetrates into the rock along a helical path under the action of an axial thrust force and a rotary torque and the action of the cutting tip is one of planing. It seems reasonable to assume, therefore, that a study of the planing action of a tool on rock would reveal much information to rotary drilling or boring.Then, we have studied on the following problems using a rock planing apparatus which is able to measure horizontal and vertical component of cutting resistance of rock: 1) effect of depth of cut, 2) effect of number of free surface, 3) effect of width of cutting tip, 4) effect of wear of cutting tip, etc.