Cosmic R-string, R-tube and Vacuum Instability

We show that a cosmic string associated with spontaneous $U(1)_R$ symmetry breaking gives a constraint for supersymmetric model building. In some models, the string can be viewed as a tube-like domain wall with a winding number interpolating a false vacuum and a true vacuum. Such string causes inhomogeneous decay of the false vacuum to the true vacuum via rapid expansion of the radius of the tube and hence its formation would be inconsistent with the present Universe. However, we demonstrate that there exist metastable solutions which do not expand rapidly. Furthermore, when the true vacua are degenerate, the structure inside the tube becomes involved. As an example, we show a "bamboo"-like solution, which suggests a possibility observing an information of true vacua from outside of the tube through the shape and the tension of the tube.Comment: 28 pages, 17 figures, v2: references added, improved arguments in sec 3.5.

Excitonic Aharonov-Bohm Effect in Isotopically Pure 70Ge/Si Type-II Quantum Dots

We report on a magneto-photoluminescence study of isotopically pure 70Ge/Si self-assembled type-II quantum dots. Oscillatory behaviors attributed to the Aharonov-Bohm effect are simultaneously observed for the emission energy and intensity of excitons subject to an increasing magnetic field. When the magnetic flux penetrates through the ring-like trajectory of an electron moving around each quantum dot, the ground state of an exciton experiences a change in its angular momentum. Our results provide the experimental evidence for the phase coherence of a localized electron wave function in group-IV Ge/Si self-assembled quantum structures.Comment: 4 pages, 4 figure

Effect of tricyclic drugs on mitochondrial membrane.

The effects of tricyclic drugs (clomipramine, imipramine, chlorpromazine and promethazine) on isolated liver mitochondria of rats were examined. All the drugs tested accelerated state 4 respiration. Their stimulative potency at concentrations below 100 microM was in the order of chlorpromazine greater than clomipramine greater than imipramine, promethazine. On state 3 respiration, the chlorine containing drugs had an inhibitive effect at high concentrations, while the other drugs seemed to have a slightly stimulative effect. These drugs stimulated latent ATPase activity of mitochondria. Clomipramine and chlorpromazine inhibited 2, 4-dinitrophenol-stimulated ATPase activity in a dose-dependent fashion. Imipramine also inhibited 2, 4-dinitrophenol-stimulated ATPase activity at high concentrations. Promethazine, however, had almost no effect. All the drugs induced potassium release from mitochondrial vesicles, and their potency was in the order of clomipramine greater than chlorpromazine greater than imipramine greater than promethazine. These results suggest that clomipramine, imipramine, chlorpromazine and promethazine cause impediments in both mitochondrial respiration and ion compartmentation, and that the chlorine containing drugs are more toxic than others on the functions of the mitochondrial membrane.</p

Effects of aggregation on methamphetamine toxicity in mice.

Methamphetamine (MA) toxicity in aggregated mice was studied by varying the number of mice and the proportion of MA treated mice kept in the same confined space. The lethality was measured 24 h after intraperitoneal injections of MA at doses ranging from 10 to 100 mg/kg. MA lethality, over a wide dose range (15 to 50 mg/kg), was higher in aggregated mice than in those maintained in isolation. The greater the proportion of MA-treated mice in aggregation was, the higher the MA lethality was. In aggregations of 10 mice, MA was lethal at lower doses than in aggregations of 5 mice. These results indicate that the lethality of MA is influenced by confinement and aggregation.</p

In vitro release of tegafur from a fatty-base suppository and in vivo bioavailability of tegafur.

This study was designed to determine the in vitro release of tegafur from a suppository and the in vivo bioavailability of tegafur in rats. Two different suppository preparations (product A-1 and product A-2) containing 750 mg of tegafur were tested for in vitro release of tegafur by the Muranishi Method (membrane diffusion method) and the partially modified paddle method (permeability through dialysis tubing). When determined by either method, the amount of tegafur released from product A-2 during the whole experimental period was significantly greater than that released from product A-1. When tested by the Muranishi method, however, the difference in the amount released during the first 10-min period was not significant. A greater bioavailability of tegafur after rectal administration was obtained by product A-2 more than product A-1. A significant correlation was observed between the in vitro release and the in vivo bioavailability. The present results indicate that there are considerable differences in physiochemical characteristics between product A-1 and product A-2.</p

Effects of exposure to cigarette smoke on intestinal propulsion in rats.

The effects of acute exposure to cigarette smoke and systemic administration of nicotine on intestinal propulsion were investigated in rats. The propulsive activity was measured as migration of charcoal powder in the intestine. This activity was suppressed by acute exposure (10 min) to cigarette smoke and by nicotine (0.5 mg/kg x 2, s.c.) administration. This intestinal suppression was more marked in the rats given nicotine than in those exposed to cigarette smoke, whereas the plasma concentrations of nicotine in both rats were similar. These results suggest that acute exposure to cigarette smoke and nicotine administration delay gastric emptying and/or suppress intestinal propulsion, and that some components other than nicotine contained in cigarette smoke may attenuate the suppression of intestinal propulsion induced by nicotine.</p

Development of an anilide-type scaffold for the thioester precursor, N-Sulfanylethylcoumarinyl amide (SECmide)

N-Sulfanylethylcoumarinyl amide (SECmide) peptide, which was initially developed for the use in the fluorescence-guided detection of promoters of N–S acyl transfer, was successfully applied to a facile and side reaction-free protocol for N–S acyl-transfer-mediated synthesis of peptide thioesters. Additionally, 4-mercapto benzyl phosphonic acid (MBPA) was proved to be a useful catalyst for the SECmide or N-sulfanylethylanilide (SEAlide)-mediated NCL reaction

Pharmacokinetic Evaluation of Omeprazole Suspension Following Oral Administration in Rats: Effect of Neutralization of Gastric Acid

In order to evaluate a clinical use of omeprazole suspension, we examined the pharmacokinetics of omeprazole after oral administration in rats. Although the administration of omeprazole suspension buffered by NaHCO3 solution did not produce a significant increase in the area under the concentration-time curve (AUC) value compared with non-buffered group, the administration of NaHCO3 buffer immediately after dosing of omeprazole suspension buffered by NaHCO3 caused a significant increase in the AUC value. These results suggest that the NaHCO3 treatment following the administration of omeprazole buffered suspension effectively decreased the degradation of the compound by gastric acid. Therefore, the successive administration of NaHCO3 solution after the omeprazole dosing seems to be a simple and useful method for the administration to patients who cannot receive tablets.</p