Preparation of microporous membranes from cation exchange membranes prepared by the paste method

A microporous membrane is prepared by treating the cation exchange membrane (Fe⁺⁺⁺ form) with an H₂O₂ aqueous solution. The cation exchange membrane is prepared by the paste method: the base membrane is prepared beforehand and then sulfonated. The preparative conditions of the base membrane were studied in connection with the characteristics of the resultant microporous membrane. Furthermore, the availability of the microporous membrane for ultrafiltration was studied by using an aqueous solution of a bovine hemoglobin.     

Computerised defect sizing using ALOK analysis in shrunk-on wheel of turbine rotor

A computerised defect evaluation system using an advanced ultrasonic technique for shrunk-on wheels of a turbine rotor has been developed. The flaw image was reconstructed by a modified ALOK method with attention to the tip diffraction echoes of stress corrosion cracking (SCC). The results of the application of this system to the mock-up wheel with artificial slits and real SCC cracks show that this system is very useful for crack sizing and locating.     

Bounds of Uncertain Interference Between Closely Located Antennas

The uncertainty in the characteristics of two antennas located close together and operating at different frequencies is considered. The formulations of antenna performance indexes on one antenna by admittance parameters are obtained with respect to the load impedance at the feed point of the other antenna. All the antenna performance indexes obtained here are expressed as the ratio of quadratic functions of the load impedance, and exact formulas are derived for the quick calculation of their bounds with respect to the load impedance which is uncertain and changes with frequency.     

Synthetic fluid inclusion logging to measure temperatures and sample fluids in the Kakkonda geothermal field, Japan

Synthetic fluid inclusion logging is a new tool to measure temperatures and sample fluids in high-temperature geothermal wells. Fluid in the microcracks of a crystal can be trapped in inclusions through healing. Fluid inclusions in quartz, for example, can be synthesized easily in geothermal boreholes and can be used as long as the host crystal is stable (e.g. α-quartz is stable up to 573°C). This technique can be applied to high-temperature geothermal wells where conventional temperature measurement methods are not feasible. Cracked crystals of quartz, soaked in silica-saturated solutions in gold or platinum capsules mounted on containers, are placed in a geothermal borehole. Geothermal fluid enters the microcracks in the crystals at the selected sampling depths, and inclusions containing ambient fluid are formed through crack healing. Trapping temperatures of fluid inclusions in quartz are determined by microthermometry using a heating stage with pressure corrections. Other cracked crystals mounted in containers with rupture disks are used for fluid sampling. The first borehole experiment was conducted at WD-1, a deep research hole drilled in the Kakkonda geothermal field, northeast Japan, from September to October 1994 (24 days). Results from the experiment confirmed that temperatures measured from fluid inclusions are consistent with borehole temperatures measured by conventional logging tools.     

Stimulation of fatty acid synthesis by 4β-phorbol-12-myristate-13-acetate in isolated rat hepatocytes

The tumor-promoting agent 4β-phorbol-12-myristate-13-acetate (TPA) is shown to be a potent stimulator of fatty acid synthesis in isolated rat hepatocytes. The maximal effect of TPA is seen at 10⁻⁶ M, and the concentration for half-maximal effect is ca. 10⁻⁸ M. Stimulation of fatty acid synthesis by TPA is shown not to require the presence of extracellular Ca⁺⁺. TPA produces a significant increase in lactate and pyruvate accumulation. The possible involvement of protein kinase C in short-term regulation of fatty acid synthesis in the liver is discussed.     

Effects of Mn,P, and mo on sulfide stress cracking resistance of high strength low alloy steels

Effects of phosphorus, manganese, and molybdenum on sulfide stress cracking (SSC) resistance were investigated by the constant load SSC test for low alloy steels with tempered martensite struc-ture and yield strength of 690 MPa to 820 MPa. The SSC threshold stress begins to decrease with an increase in yield strength at a certain yield strength (an SSC critical strength). The fraction of inter-granular fracture surface begins to increase with an increase in yield strength at the SSC critical strength, while the fracture mode becomes transgranular below this strength. Furthermore, there ex-ists a relationship between an increase in the fraction of intergranular fracture surface and a decrease in the SSC threshold stress. A decrease in phosphorus and manganese content and an increase in molybdenum content make the SSC critical strength higher. These changes in content of chemical elements, therefore, lead to an increase in the SSC threshold stress due to a decrease in the amount of intergranular fracture surface above the SSC critical strength. Below the SSC critical strength, however, the change of the SSC threshold stress is not observed because the fracture mode remains fully transgranular. The SSC critical strength could be represented as a function of a parameter com-posed of manganese and phosphorus contents.     

Structure-activity relationships of spontaneous nitric oxide releasers, FK409 and its derivatives

(+/-)-(E)-4-Ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (FK409) shows both potent in vitro vasorelaxant and antiplatelet activities via nitric oxide (NO) generated spontaneously from the compound. In this study, we measured spontaneous NO-releasing rates of a series of FK409 derivatives, of which chain lengths or substituents were systematically modified, in sodium-phosphate buffer solution at pH 7.4. Furthermore, we studied their in vitro antiplatelet and vasorelaxant effects to evaluate relationships between spontaneous NO-releasing activities of FK409 analogs and their biological activities. FK409 derivatives were found to possess different spontaneous NO-releasing rates and biological activities according to their structural modification. In addition, these studies revealed a close correlation between NO-releasing rates of FK409 derivatives and their in vitro antiplatelet activities in human platelet-rich plasma, whereas the in vitro vasorelaxant activities of these compounds in isolated rat aorta did not correlate with the rates of NO liberation. The vasorelaxant effects were supposed to be affected by the structural properties of FK409 derivatives as well as their NO-releasing abilities.