Antioxidant ortho-benzoyloxyphenyl acetic acid ester,vaccihein A,from the fruit of rabbiteye blueberry (Vaccinium ashei)

A new ortho-benzoyloxyphenyl acetic acid ester, called vaccihein A (1), was isolated from the fruit of rabbiteye blueberry (Vaccinium ashei). The chemical structure was determined on the basis of spectroscopic data. Compound 1 had antioxidative activity using the ferric thiocyanate method. In addition, 1 showed a scavenging effect on the stable free radical 1,1-diphenyl-2-picrylhydrazyl.     

Electron and ion transfer through multilayers of gold nanoclusters covered by self-assembled monolayers of alkylthiols with various functional groups

The electrochemical characteristics of various kinds of multilayers of gold nanoclusters (GNCs) were investigated. Two types of gold nanoclusters, one covered by self-assembled monolayers (SAMs) of mercaptoundecanoic acid (MUA), hexanethiol (C6SH), and ferrocenylhexanethiol (FcC6SH), MHF-GNC, and the other with MUA and C6SH, MH-GNC, were used. The multilayers were constructed on a Au(111) surface based on a carboxylate/metal cation (Cu++)/carboxylate or carboxylate/cationic polymer (poly(allylamine hydrochloride):PAH)/carboxylate electrostatic interaction. While the multilayers constructed by the former method were stable only in nonaqueous solutions, those constructed by the latter method were stable even in aqueous solutions. Electrochemical measurements of the multilayers of MHF-GNCs showed a pair of waves corresponding to the redox of the ferrocene group around 350-480 mV and the charge of these peaks, i.e., the amount of adsorbed GNC, increased linearly with the construction cycle up to 6 cycles in the former and to 18 cycles in the latter. A rather reversible redox response of the ferrocene moiety was observed even at the gold electrodes with five GNC layers of two different sequences in which MHF-GNC exists as the layer closest to the gold electrode, ie., the first layer, or as the outermost layer with MH-GNC in the other layers. These results show the facile transfer of electrons and ions through the multilayers of the SAM-covered GNCs and electron transfer between the ferrocene moiety and the Au(111) electrode takes place through the GNC cores by hopping.     

Observation of light propagation by holography with a picosecond pulsed laser

We demonstrate the propagation of a light pulse undergoing refraction and total refraction inside a glass block as well as diffraction at a grating. Observation of a frameless, continuous motion picture of the light propagation is possible by recording of hologram with a picosecond pulsed laser. It is shown that the direction of the pulse changes as a result of refraction, the pulse's speed decreases inside a glass block, and the pulse travels a zigzag path by total refraction. The pulse fronts of the diffracted light propagating parallel to the grating surface are also demonstrated.     

DNA strand exchange stimulated by spontaneous complex formation with cationic comb-type copolymer

Cationic comb-type copolymers (CCCs) composed of a polycation backbone and water-soluble side chains accelerate by 4-5 orders the DNA strand exchange reaction (SER) between double helical DNA and its homologous single-strand DNA. The accelerating effect is considered due to alleviation of counterion association during transitional intermediate formation in sequential displacement pathway. CCCs stabilize not only matured hybrids but also the nucleation complex to accelerate hybridization.     

Anionic polymerization of methyl methacrylate initiated with lithium diphenylamide (Ph2NLi) in the presence of divalent transition metal halide

Anionic polymerization of methyl methacrylate (MMA) in the presence of divalent transition metal halide (MX₂ = FeBr₂, MnCl₂, CoCl₂, NiBr₂) was investigated. Initiating systems with various combinations of MX₂, lithium diphenylamide (Ph₂NLi), and organolithium (RLi, where R = nBu, Me) were effective to giving a high yield of poly(methyl methacrylate)s (PMMAs) at ?78 °C in toluene. The tacticity of the resulting PMMAs was highly dependent on the combination of the reagents used for the generation of the initiating systems within a syndiotactic (rr = 59%) to isotactic (mm = 65%) range. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 31–37, 2004     

Plasma erosion opening switch using laser-produced plasma

In order to construct a practical inductive energy storage pulsed power generator, an opening switch which can repeatedly conduct a large current and then rapidly interrupt this current is necessary. Though the plasma erosion opening switch (PEOS) can interrupt a large current rapidly, the effective number of switch operations is limited because of the decrease of the carbon sprayed on the insulator with each shot. A PEOS using a laser-produced plasma, which can possibly be operated for hundreds of thousands of shots without maintenance, is proposed, and its operation as an opening switch is confirmed experimentally     

Amine-salt-controlled, catalytic asymmetric conjugate addition of various amines and asymmetric protonation

The combined use of chiral Pd complex 2 and amine salt enabled completely regulated release of free nucleophilic amine. Under these conditions, an efficient catalytic asymmetric conjugate addition of various amines was achieved to afford beta-amino acid derivatives in high chemical yields with up to 98% ee. Furthermore, a highly enantioselective protonation in 1,4-addition of amine was also developed. [reaction: see text]     

Resonant heating of a cluster plasma by intense laser light

The heating of a single argon (Ar) cluster by a strong laser field is studied using an electrostatic particle-in-cell code for a range of intensities and cluster sizes. Heating is dominated by a nonlinear resonant absorption process involving energetic electrons transiting through the cluster. This process gives rise to a threshold in field strength for strong absorption and controls the dielectric properties of the cluster.     

Characteristics of coated copper wire specimens using high frequency ultrasonic complex vibration welding equipments

Welding characteristic of thin coated copper wires were studied using 40, 60, 100 kHz ultrasonic complex vibration welding equipments with elliptical to circular vibration locus. The complex vibration systems consisted of a longitudinal-torsional vibration converter and a driving longitudinal vibration system. Polyurethane coated copper wires of 0.036 mm outer diameter and copper plates of 0.3 mm thickness and the other dimension wires were used as welding specimens. The copper wire part is completely welded on the copper substrate and the insulated coating material is driven from welded area to outsides of the wire specimens by high frequency complex vibration.