Comparative studies of glycoprotein Ib in heparin coated and nonheparin coated extracorporeal circulation circuits

Contact between blood and artificial materials has various effects on blood. Impairment of platelet function is an especially important and well known effect, but its precise mechanism is not clearly understood. The authors constructed a circulation model to investigate the effect of extracorporeal circulation on platelet membrane glycoproteins (GPs), especially GP Ib, and to compare the changes in GP Ib in heparin coated (group C) and nonheparin coated (group N) circuits. As determined by flow cytometry, GP Ib in both groups decreased on initiating circulation, but the decrease in group N was significantly larger than that in group C. There was no observed change in GP IIb/IIIa levels in either group. The extent of shear stress induced platelet aggregation significantly decreased during circulation in both groups. Decreases in the extent of shear stress induced platelet aggregation were significantly less with the use of heparin coated circuits. In addition, the amount of GP Ib in the high speed pellet decreased progressively during circulation in both groups. In contrast, the amount of GP Ib in the Triton insoluble (low speed) pellet increased dramatically during circulation. However, expression of GP Ib in the Triton soluble platelet fraction was low in both groups. From the results, it was concluded that the cause of the decrease in platelet function during extracorporeal circulation is attributable to the internalization of GP Ib from the platelet surface inside the platelet. It also can be said that a heparin coated circuit is one effective means of controlling this change.     

High-Temperature Strength of Melt-Infiltrated SiC-Mo(Al,Si)2 Composites

High-temperature fracture behavior of melt-infiltrated SiC-Mo(AI,Si)₂ composites was studied. The composites exhibited moderate strength up to ∼1600°C under a fast loading rate. The softening of the Mo(Al,Si)₂ phase determined dominantly the temperature over which the strength decreased. The composite with finer microstructure revealed a higher level of strength over the whole temperature range. At 1580°C, however, the composites revealed distinct strength degradation at a reduced loading rate.     

Influence of axisymmetric initial deflections on the thermal buckling of truncated conical shells

The thermal buckling of uniformly heated, clamped, truncated conical shells with axisymmetric initial deflections is theoretically studied. The axisymmetric initial deflections are represented by a cosine function. The Donnell-type basic equations governing the finite deformation of conical shells are solved by means of a finite difference procedure. It is found that the effect of axisymmetric initial deflections on the thermal buckling of truncated conical shells is quite significant for the axially constrained case, but negligible for the axially free one except very shallow cones. The thermal buckling of a clamped annular plate with the axisymmetric initial deflection is also examined.     

Developmental changes in mouse placental cells from several stages of pregnancy in vivo and in vitro

Developmental changes in mouse placentae from the 6th to the 18th day of pregnancy were studied in vivo and in vitro. Placental volume increased from the 6th to the 18th day of pregnancy; however, the total number of cells per placenta reached a plateau on the 14th day. Decidual cells were predominant in the placenta on the 6th day. Placentae obtained from the 10th to the 18th day contained decidual cells, trophoblastic (labyrinth and spongiotrophoblast) cells, and trophoblast giant cells. Decidual cells increased in number from the 6th to the 10th but decreased on the 14th day, whereas trophoblastic cells increased linearly until the 14th day. Two types of placental cells were distinguished in vitro: small fibroblast-like cells and large flattened cells containing 2-3 nuclei. The large cells reacted to anti-desmin antibody, indicating their decidual character. The small cells reacting to anti-keratin antibody appeared to be trophoblastic cells. Decidual cells from all days of gestation were nonproliferative, regressing with time in culture. 17 beta-Estradiol (E, 10(-9) and 10(-8) M), progesterone (P, 10(-10), 10(-9), and 10(-8) M), and a combination of E and P (10(-9) M each) stimulated proliferation of the trophoblastic cells only from the 6th and the 10th days. Keoxifene (2 x 10(-7) M), but not tamoxifen, significantly inhibited the E-induced proliferation of the trophoblastic cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Study on Lubricant Depletion Induced by Laser Heating in Thermally Assisted Magnetic Recording Systems: Effect of Lubricant Thickness and Bonding Ratio

In this study, we have carried out fundamental research on lubricant depletion due to laser heating in thermally assisted magnetic recording. In particular, we investigated the effects of lubricant film thickness and lubricant bonding ratio on lubricant depletion. Conventional lubricants Zdol2000 and Ztetraol2000 were used. The lubricant depletion characteristics due to laser heating were found to depend largely on the lubricant film thickness and material. That is, for films thicker than one monolayer, the lubricant depletion depth increased with the laser-irradiation duration, whereas the thickness of the lubricant after laser irradiation on the diamond-like carbon (DLC) films tended to remain at a constant film thickness of one monolayer. The lubricant depletion width gradually increased as the laser irradiation duration increased. The increasing trends for the lubricant depletion width were quantitatively very similar and almost independent of the initial lubricant film thickness. However, for lubricant films with thicknesses less than one monolayer, the lubricant depletion depth was very small. The lubricant depletion width increased remarkably to several hundred micrometers as the laser irradiation duration increased. The lubricant depletion depth and width were much smaller for Ztetraol2000 than Zdol2000. In addition, the lubricant-bonding ratio was found to greatly affect the lubricant depletion characteristics due to laser heating. In other words, the lubricant depletion depth and width decreased as the bonding ratio increased. The lubricant depletion mechanism involves the evaporation of mobile lubricant molecules when the maximum attained temperature is less than 100 °C. Another suggested lubricant depletion mechanism involves the thermocapillary stress effect, which is induced by the disk surface temperature gradient resulting from the non-uniformity of the laser spot intensity distribution.     

Circular tunnel in a semi-infinite aquifer

The steady gravity flow that is generated by a circular tunnel disturbing the hydrostatic state of a semi-infinite, homogeneous and isotropic aquifer is solved exactly. Many aspects of the flow are found in closed analytical forms such as the water inflow, pressure, leakage and recharging infiltration, which give a complete view of the aquifer in the drained steady state. It is found that the maximum value of the recharging infiltration does not exceed the hydraulic conductivity allowing stating a criteria for recharge intervention to ensure the stability of the aquifer. In addition to the main results, two aspects of the water inflow are treated. These are the necessary modifications that are to be considered in the case of an inclined water table and in the case of a lined tunnel that develops a constant internal pressure. It is also found that under an inclined water table a tunnel may cease to drain on its complete circumferential edge and a limiting condition is stated. Furthermore, the Muskat–Goodman and other water inflow predictions are compared to the exact gravity water inflow.     

Metal-Coated <100>-Cut GaAs Coupled to Tapered Parallel-Plate Waveguide for Cherenkov-Phase-Matched Terahertz Detection: Influence of Crystal Thickness

The influence of crystal thickness of metal-coated <100>-cut GaAs (M-G-M) on Cherenkov-phase-matched terahertz (THz) pulse detection was studied. The M-G-M detectors were utilized in conjunction with a metallic tapered parallel-plate waveguide (TPPWG). Polarization-sensitive measurements were carried out to exemplify the efficacy of GaAs in detecting transverse magnetic (TM)- and transverse electric (TE)-polarized THz waves. The reduction of GaAs’ thickness increased the THz amplitude spectra of the detected TM-polarized THz electro-optic (EO) signal due to enhanced electric field associated with a more tightly-focused and well-concentrated THz radiation on the thinner M-G-M. The higher-fluence THz beam coupled to the thinner M-G-M improved the integrated intensity of the detected THz amplitude spectrum. This trend was not observed for TE-polarized THz waves, wherein the integrated intensities were almost comparable. Nevertheless, good agreement of spectral line shapes of the superposed TM- and TE-polarized THz-EO signals with that of elliptically polarized THz-EO signal demonstrates excellent polarization-resolved detection capabilities of M-G-M via Cherenkov-phase-matched EO sampling technique.