Low Energy Effective Action for Dilatonic Braneworld —A Formalism for Inflationary Braneworld—

We derive the low energy effective action for the dilatonic braneworld. In the case of the single-brane model, we find the effective theory is described by the Einstein-scalar theory coupled to the dark radiation. Remarkably, the dark radiation is not conserved in general due to a coupling to the bulk scalar field. The effective action incorporating Kaluza-Klein (KK) corrections is obtained and the role of the AdS/CFT correspondence in the dilatonic braneworld is revealed. In particular, it is shown that CFT matter would not be confined to the braneworld in the presence of the bulk scalar field. The relation between our analysis and the geometrical projection method is also clarified. In the case of the two-brane model, the effective theory reduces to a scalar-tensor theory with a non-trivial coupling between the radion and the bulk scalar field.     

Biomimetic reactions of some macrocyclic diterpenes

Some macrocyclic diterpenes derived from euphohelioscopin A and euphornin have been stereoselectively converted into the jatropholane- and daphnane-type compounds and the known tricyclic compound which has been treated with phCOCl - pyridine to afford euphohelionone, the new type of diterpene isolated from euphorbia helioscopia L.     

Effect of pressure on the conductivities of HCl and KCl in water at 0°C

The electrical conductivities of hydrochloric acid and potassium chloride in water have been measured in the concentration range of 3×10 ^–4 –10 ^–3 moles-dm ^–3 at 0°C up to 3500 bar. The limiting molar conductance (₀) for HCl increases with increasing pressure, while ₀(KCl) has a maximum around 1700 bar. The excess conductance of hydrogen ion [ ₀ ^E =₀(HCl)–₀(KCl)] increases with increasing pressure. Its pressure dependence indicates that the reorientation of water molecules, which is the rate-determining step in the proton jump, becomes faster at higher pressure. This anomaly is attributed to the distortion with pressure of the hydrogen bonds in water.     

Electrical conductivity of Th3P4-type EnLn2S4

Electrical conductivity measurements of Th₃P₄-type EuLn₂S₄ (Ln = LaGd) compounds have been made as functions of temperature and sulfur vapor pressure. These compounds are all p-type semiconductors, and their conductivities at room temperature have almost the same values for the specimens from EuLa₂S₄ to EuNd₂S₄ but increase on going from EnNd₂S₄ to EuGd₂S₄. In addition, the conductivity of EuGd₂S₄ is sensitive to sulfur vapor pressure and obeys the relationship . The mechanism of electrical transport in these compounds is discussed.     

A new family of pi-conjugated delocalized biradicals: Electronic structures of 1,4-bis(2,5-diphenylimidazol-4-ylidene)cyclohexa-2,5-diene

A new family of pi-conjugated delocalized biradical compound is developed. The solution of 1,4-bis(2,5-diphenylimidazol-4-ylidene)cyclohexa-2,5-diene shows the ESR signal consisting of a moderately broad unresolved line, Delta H(pp) approximately 1 mT, at room temperature. The presence of the thermal equilibrium between a triplet biradical state and a singlet state is confirmed by the ESR measurements, and the spin concentration is determined as 7.90 x 10(21) spin/mol at 300 K. The spin concentration can also be controlled by modifying the molecular planarity. Moreover, the unrestricted DFT/B3LYP calculations suggest the biradical character of the singlet ground state, and the modulation of the energy gap between the singlet state and the triplet state is investigated from the theoretical point of view. Controlling the equilibrium between a diamagnetic state and a paramagnetic state will provide significant progress in the field of biradical chemistry, and the materials with the biradical character in a ground state will lead to a novel development of molecular-based organic magnets.     

Some studies on the solid solutions in the systems Sr2Nb2O7Eu2Nb2O7 and Sr2Ta2O7Eu2Ta2O7

Preparation of new solid solutions containing divalent europium have been tried in the systems Eu₂Nb₂O₇Sr₂Nb₂O₇ and Eu₂Ta₂O₇Sr₂Ta₂O₇. These solid solutions described as Eu_2xSr_2(1?x)M₂O₇ (M = Nb and Ta) exist in a pure orthorhombic phase in a limited region of x from 0 to about 0.5. The compounds with compositions close to Eu₂M₂O₇ exist but techniques have not been found to prepare them in pure form.     

An efficient synthetic method for macrocyclic ketones by intramolecular alkylation of protected cyanohydrins,and its application to the syntheses of muscone and exaltone

A simple synthetic method for macrocyclic ketones based on intramolecular alkylation of carbanion, generated from protected cyanohydrin is reported. Subsequent mild treatment with acid and base of the cyclized products leads to macrocyclic ketones in high yields. The reaction is rapid and irreversible, and hence required short reaction time. The method was successfully applied to the syntheses of cyclohexadecanone and trans-2-cyclopentadecenone as a precursor of (±)-muscone and exaltone.     

Application of palladium catalyses to a simple synthesis of (±)-pyrethrolone

By sequential application of three palladium catalyzed reactions, namely, palladium catalyzed telomerization of butadiene with phenol, oxidation of terminal olefin of the telomer to methyl ketone, and palladium catalyzed elimination of phenol, an E and Z mixture of 5,7-octadien-2-one was prepared in a high yield. This compound was converted to an E and Z mixture of pyrethrolone. The Z form of pyrethrolone was separated from the E isomer by selective adduct formation of the latter with tetracyanoethylene.     

Photochemical dimerization of p-benzoquinone methyl derivatives in crystals

Photochemical dimerization of p-benzoquinone and its methyl derivatives in crystals is discussed assuming that the reactivity is parallel with the stabilization energy of the transient complex. The calculation is carried out by taking both the terms of electronic structure of the monomer molecule and the intermolecular arrangement in the monomer crystal into consideration. Concerning the ability of photodimerization, the result obtained is qualitatively satisfactory. However, such an agreement with experiment cannot be obtained if either the electronic term or the geometrical term is ignored.

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Zusammenfassung Die photochemische Dimerisierung von p-Benzochinon und seines Methylderivates im Kristallzustand wird diskutiert; dabei wird angenommen, daß die Reaktivität parallel zur Stabilisierungsenergie des Übergangskomplexes ist. Die Berechnung wird so durchgeführt, daß sowohl die Elektronenstruktur des monomeren Moleküls als auch die Lage der Moleküle im Kristall des Monomeren berücksichtigt wird. Die Ergebnisse bezüglich der Fähigkeit zur Photodimerisierung sind qualitativ zufriedenstellend. Eine derartige Übereinstimmung mit dem Experiment kann jedoch nicht erhalten werden, wenn entweder der elektronische Beitrag oder der geometrische Beitrag vernachlässigt werden.

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Résumé La dimérisation photochimique de la p-benzoquinone et de ses dérivés méthylés dans les cristaux est discutée en supposant que la réactivité évolue parallèlement à l'énergie de stabilisation du complexe de transition. Le calcul est effectué en tenant compte de la structure électronique du monomère et de l'arrangement intermoléculaire dans le cristal du monomère. Le résultat obtenu est satisfaisant qualitativement en ce qui concerne la facilité de photodimérisation. Cependant, un tel accord avec l'expérience ne pourrait être obtenu si l'un des deux termes électronique ou géométrique était négligé.