Stabilizing control, system preventing loss of synchronism fromextension and its actual operating experience

This paper presents a stabilizing control system that was implemented to the power system of Tokyo Electric Power Company and worked successfully, shedding the minimum number of generators and preventing the extension of loss of synchronism to the other generators when a severe fault occurred on May 22, 1992. The stabilizing control system measures voltage and current at the rate of 600 Hz, predicts the change of phase angles of generators and decides the minimum number of generators to be shed for stabilization when instability is predicted and sheds them     

Fast generation shedding equipment based on the observation ofswings of generators

A novel method and recently developed stabilizing equipment to prevent the loss of synchronism of generators in pumped-storage plants due to spreading are presented. The method includes functions to estimate the swing of each generator by using online generator output sampled 600 times per second after an occurrence of a disturbance (such as a fault, faulty equipment, etc). Generator swing 200-300 milliseconds ahead and loss of synchronism between generators in pumped-storage plants and those in thermal and nuclear plants can be predicted 200-300 ms ahead, and the number of generators that must be shed to maintain stability can be decided     

Properties of syndiotactic-rich poly(vinyl alcohol) thin film in water. VII. Elastic behavior of swollen film in water through heating/cooling or cooling/heating cycles

The thermoelastic behavior for highly swollen films of syndiotactic-rich poly(vinyl alcohol) (s-PVA) was ascertained under loads in water through heating/cooling or cooling/heating cycles (in the range of 25–70°C). The s-PVA films kept at the high temperature of 70°C behaved as a perfect elastomer through the cooling/heating cycle and had very low Young's modulus, 2–3.5 × 10⁶ dyn/cm². When highly swollen s-PVA films were kept at lower temperatures below about 50°C for a long time, microcrystals were formed or propagated in the s-PVA films and plastic deformation occurred in addition to elastic deformation through heating process. The microcrystalline growth and propagation at lower temperatures were supported by an increase in Young's modulus and a decrease in the molecular weight between junctions.     

Association between ligand-induced conformational changes of integrin IIbbeta3 and IIbbeta3-mediated intracellular Ca2+ signaling

Platelet IIbbeta3 is a prototypic integrin and plays a critical role in platelet aggregation. Occupancy of IIbbeta3 with multivalent RGD ligands, such as fibrinogen, induces both expression of ligand-induced binding sites (LIBS) and IIbbeta3 clustering, which are thought to be necessary for outside-in signaling. However, the association between LIBS expression and outside-in signaling remains elusive. In this study, we used various IIbbeta3-specific peptidomimetic compounds as a monovalent ligand instead of fibrinogen and examined the association between LIBS expression and outside-in signaling such as IIbbeta3-mediated intracellular Ca2+ signaling. Using a set of monoclonal antibodies (MoAbs) against LIBS, we showed that antagonists can be divided into two groups. In group I, antagonists can induce LIBS on both IIb and beta3 subunits. In group II, antagonists can induce LIBS on the IIb subunit, but not on the beta3 subunit. Inhibition studies suggested that group I and group II antagonists interact with distinct but mutually exclusive sites on IIbbeta3. Neither group I nor group II antagonist increased intracellular Ca2+ concentrations ([Ca2+]i) in nonactivated platelets. All antagonists at nanomolar concentrations abolished the increase in [Ca2+]i in 0.03 U/mL thrombin-stimulated platelets, which is dependent on both fibrinogen-binding to IIbbeta3 and platelet-aggregation. However, only group I antagonists at higher concentrations dose-dependently augmented the [Ca2+]i increase, which is due to aggregation-independent thromboxane A2 production. This increase in [Ca2+]i was not observed in thrombasthenic platelets, which express no detectable IIbbeta3. Thus, only the group I antagonists, albeit a monovalent ligand, can initiate IIbbeta3-mediated intracellular Ca2+ signaling in the presence of thrombin stimulation. Our findings strongly suggest the association between beta3 LIBS expression and IIbbeta3-mediated intracellular Ca2+ signaling in platelets.     

Enhanced expression of PAI-1 in visceral fat: possible contributor to vascular disease in obesity

The presence of obesity increases the risk of thrombotic vascular diseases. The role of fat accumulation and its effect on plasminogen activator inhibitor-1 (PAI-1) levels was investigated in humans and animals. Plasma PAI-1 levels were closely correlated with visceral fat area but not with subcutaneous fat area in human subjects. PAI-1 mRNA was detected in both types of fat tissue in obese rats but increased only in visceral fat during the development of obesity. These data suggest that an enhanced expression of the PAI-1 gene in visceral fat may increase plasma levels and may have a role in the development of vascular disease in visceral obesity.     

P1 specificity of aqualysin I (a subtilisin-type serine protease) from Thermus aquaticus YT-1, using P1-substituted derivatives of Streptomyces subtilisin inhibitor

Aqualysin I is an alkaline serine protease isolated from Thermus aquaticus YT-1, an extreme thermophile. We have measured the P1-specificity of aqualysin I, using wild-type and five P1-substituted derivatives of Streptomyces subtilisin inhibitor (SSI). SSIs efficiently inhibited the activity of aqualysin I, with low substrate specificity. Charge and hydrophobicity of side chain of the P1 amino acid residue showed no significant effect to the P1-specificity of this enzyme.     

Effect of addition of saccharose on gelation of aqueous poly(vinyl alcohol) solutions

The properties of poly(vinyl alcohol) (PVA) hydrogels containing saccharose were examined. The effect of the addition of saccharose to atactic PVA (α-PVA) gels on their melting temperatures was larger than that for syndiotacticity-rich PVA (s-PVA) gels and the melting temperature was above 100°C for α-PVA gels with saccharose contents of 60 wt %. However, the fusion enthalpy (ΔH) of the α-PVA gels was at most 100 kJ/mol. The release of solvent (water/saccharose) from gels in air decreased with an increase in the saccharose content and the equilibrium was achieved after standing for 20 days for the α-PVA and s-PVA gels with saccharose contents above 40 and 20 wt %, respectively. © 1995 John Wiley & Sons, Inc.     

Orientation of polymer chains in films of syndiotactic-rich poly(vinyl alcohol)

The infrared spectra of the films of syndiotactic-rich poly(vinyl alcohol) (s-PVA) prepared by the casting, frame, and bubble methods were obtained. The band at 705 cm^?1 decreased with the increased inclination of the film plane to the direction of the irradiation of infrared rays and was related to the orientation of the molecules in the adsorbed phases of both sides of film.     

Beta-ray photography of lyophilized animal sections

A new photographic method that images the density distribution of lyophilized animal sections approximately 50 microns in thickness is described. The new method involves sandwiching the animal section between a radiation sensor and a 147Pm planar radiation source. Either conventional photographic film or an imaging plate for radioluminography can be used as the sensor. The method described herein will find promising applications in whole body autoradiography as well as in the study of osteoporosis in experimental animals.