Regioselective synthesis of flavone derivatives via DMAP-catalyzed cyclization of o-alkynoylphenols

A catalytic amount of DMAP promoted cyclization of o-alkynoylphenols via a 6-endo cyclization mode leading to flavone derivatives in high yields without forming 5-exo cyclized aurone derivatives. Utilizing this method, methoxy substituted flavone and alkyl substituted γ-benzopyranone derivatives were synthesized.     

New strong fibrates with piperidine moiety

New fibrates containing piperidine, 4-hydroxypiperidine, piperidin-3-ene, and piperazine moieties in the structures were synthesized and evaluated. Among the synthesized compounds, 2-[3-[1-(4-fluorobenzoyl)-piperidin-4yl]phenoxyl-2-methylpropanoic acid (9aA: AHL-157) showed very superior activities in decreasing triglyceride, cholesterol, and blood sugar compared to bezafibrate in mice and rats.     

5 + 2] Cycloaddition reaction of 2-vinylaziridines and sulfonyl isocyanates. Synthesis of seven-membered cyclic ureas

The [5 + 2] cycloaddition reaction of 2-vinylaziridines with sulfonyl isocyanates proceeded smoothly under mild conditions, and various cyclic ureas were isolated in high yields. The remarkable solvent effect on the reaction was observed, and the preferential formation of the seven-membered ring occurred when the reaction was carried out in CH(2)Cl(2). The scope and limitation were studied, and the mechanism of this reaction was discussed. This study provides a new and simple method for the synthesis of seven-membered cyclic ureas.     

Stability and the equilibrium selenium vapor pressure of the VSe2 phase

Determination of the homogeneity range of the VSe₂ phase was made. It extends from V_1.01Se₂ to V_1.18Se₂ at 800°C and from V_1.04Se₂ to V_1.10Se₂ at 300°C. The selenium-rich limit of the adjacent monoclinic phase is about V_1.20Se₂ between 700 and 1000°C. The two-phase region between monoclinic and the VSe₂ phases extends from V_1.18Se₂ to V_1.25Se₂ at lower temperatures. Above 700°C, the mixture of two phases becomes a pseudosingle phase of a mixed-layer type. Equilibrium vapor pressures of selenium on the solid V_xSe₂ (x = 1.04–1.28) were measured by a quartz Bourdon gauge between 600 and 1000°C. Activities and other partial molar quantities were evaluated. Stability of the vanadium atoms in the CdI₂-like V_xSe₂ phase was studied. A statistical model was applied for the nonstoichiometric V_xSe₂ with the CdI₂-like structure. Vanadium atoms in the vanadium-rich layers are more stabilized than those in the vanadium-poor layers, and the differences between each stabilizing energy was about 20.0 kcal/mole.     

Soot particles in piston-top pool fires and exhaust at 5 and 15 MPa injection pressure in a gasoline direct-injection engine

This study shows the structure of soot particles sampled directly from wall wetting-induced pool fires formed on the piston top in a spark-ignition direct-injection (SIDI) engine. Of particular interest is its variation with injection pressure considering the current trend of high-pressure DI system development to reduce engine-out particulate emissions. Thermophoretic particle sampling was performed for transmission electron microscope (TEM) imaging, which was post-processed for statistical analysis of key morphology and internal structure parameters. These include the size distribution of soot aggregates and primary particles as well as carbon-layer fringe-to-fringe gap and concentricity. With the fixed engine speed and load conditions, in-flame soot particles are compared to the exhaust particles sampled simultaneously at selected 5 and 15 MPa injection pressures corresponding to low-speed/low-load and high-speed/high-load in practical engine operation. From the TEM images and statistical analysis, it was found that more concentrated and taller pool fire developed for 5-MPa injection leads to smaller soot aggregates composed of smaller soot primary particles due to suppressed soot growth in fuel-rich flames. However, the soot particles formed in 15-MPa injection-induced pool fires are at a more reactive status evidenced by less defined core-shell boundaries and higher fringe separation. The higher soot reactivity results in enhanced soot oxidation, which explains smaller soot aggregates and primary particles found for the 15-MPa injection in the exhaust sample.     

Total Synthesis and Biological Evaluation of Siladenoserinol A and its Analogues

The total synthesis of siladenoserinol A, an inhibitor of the p53–Hdm2 interaction, has been achieved. AuCl₃‐catalyzed hydroalkoxylation of an alkynoate derivative smoothly and regioselectively proceeded to afford a bicycloketal in excellent yield. A glycerophosphocholine moiety was successfully introduced through the Horner–Wadsworth–Emmons reaction using an originally developed phosphonoacetate derivative. Finally, removal of the acid‐labile protecting groups, followed by regioselective sulfamate formation of the serinol moiety afforded the desired siladenoserinol A, and benzoyl and desulfamated analogues were also successfully synthesized. Biological evaluation showed that the sulfamate is essential for biological activity, and modification of the acyl group on the bicycloketal can improve the inhibitory activity against the p53–Hdm2 interaction.     

Improved direct measurement of A(b) and A(c) at the Z(0) pole using a lepton tag

The parity violation parameters A(b) and A(c) of the Zb(b) and Zc(c) couplings have been measured directly, using the polar angle dependence of the polarized cross sections at the Z(0) pole. Bottom and charmed hadrons were tagged via their semileptonic decays. Both the electron and muon analyses take advantage of new multivariate techniques to increase the analyzing power. Based on the 1993-1998 SLD sample of 550,000 Z(0) decays produced with highly polarized electron beams, we measure A(b) = 0.919+/-0.030(stat)+/-0.024(syst), and A(c) = 0.583+/-0.055(stat)+/-0.055(syst).     

Layered superconductors in high magnetic fields

We investigate the possible occurrance of partially depaired states in superconducting intercalated layered systems. Those states are discussed as a possible explanation of the high critical fields found in some of these materials. It is shown that the Chandrasekhar-Clogston limit does not apply to those states mentioned above and that the maximum field compatible with superconductivity is a sensitive function of the shape of the Fermi surface. Mean free path and spin-orbit effects on the partially depaired state are investigated. An experiment is proposed to decide between the partially depaired state and a large spin-orbit scattering rate as possible explanations for the large critical fields.     

Echoic memory of a single pure tone indexed by change-related brain activity

Background  

The rapid detection of sensory change is important to survival. The process should relate closely to memory since it requires that the brain separate a new stimulus from an ongoing background or past event. Given that sensory memory monitors current sensory status and works to pick-up changes in real-time, any change detected by this system should evoke a change-related cortical response. To test this hypothesis, we examined whether the single presentation of a sound is enough to elicit a change-related cortical response, and therefore, shape a memory trace enough to separate a subsequent stimulus.