Organic layered crystals with adjustable interlayer distances of 1-naphthylmethylammonium n-alkanoates and isomerism of hydrogen-bond networks by steric dimension

A series of 1-naphthylmethylammonium n-alkanoates from acetate to triacontanoate produce isomorphic layered structures in the crystalline state. The interlayer distances, d-spacings, are proportional to the lengths of the alkyl chains. This is attributed to synergic intermolecular interactions; pi-pi and CH-pi interactions of the naphthalene rings between the cations, hydrophobic interactions of the alkyl chains, and two-dimensional hydrogen-bond networks between the primary ammonium cations and the carboxylate anions. Salts made from carboxylic acids wider than 5.5 A in the cross sections produce another columnar structure with a one-dimensional ladder-type hydrogen-bond network. Steric parameters of the acid components provide an explanation for the isomerism of the hydrogen-bond network.     

Novel cofacial oxidative coupling reaction of phosphinine in the presence of CuI and ClO4-

2,4,6-triphenylphosphinine (TPP) underwent unprecedented cofacial oxidative coupling to form a novel C2-symmetric cage compound, having extremely long C-C bonds.     

Island dynamics in the large-helical-device plasmas

In the Large Helical Device plasma discharges, the size of an externally imposed island with mode number ( n/m = 1/1) decreases substantially when the plasma is collisionless ( nu(*)< approximately 1) and the beta is finite ( > approximately 0.1%) at the island location. For the collisional plasmas with finite beta, on the other hand, the size of the island increases. However, there is a threshold in terms of the vacuum island size below which the island enlargement is not seen.     

Single-photon detector for long-distance fiber-optic quantum key distribution

We have investigated the performance of an InGaAs/InP avalanche photodiode for photon counting at 1550 nm in the temperature range of thermoelectric cooling. A quantum efficiency of 13.7% was obtained at -55 degrees C , while the dark-count probability per gate (?1 ns) was kept as small as 2.4x10(-5) . The developed single-photon detector would yield a 104.4-km fiber-optic quantum key distribution in the ideal condition.     

Conjugate addition of organosiloxanes to alpha,beta-unsaturated carbonyl compounds catalyzed by a cationic rhodium complex

[reaction: see text] A novel, additive-free, and clean conjugate addition reaction of organosiloxanes to alpha,beta-unsaturated carbonyl compounds catalyzed by a cationic rhodium complex in water-containing solvent has been developed. A plausible reaction mechanism involving the additive-free transmetalation step between the rhodium complex and the silicon reagent is proposed.     

Reaction of N,N-dimethylselenocarbamoyl chloride with nucleophiles. Preparation of diselenocarbamates, selenothiocarbamates, and selenoureas

Reactions of N,N-dimethylselenocarbamoyl chloride prepared by using LiAlHSeH with nucleophiles such as lithium alkylselenolate, lithium alkylthiolate, and amines afford the corresponding diselenocarbamates, selenothiocarbamates, and selenoureas. The crystal structure of the Se-phenyl N,N-dimethyldiselenocarbamate was also determined by X-ray diffraction.     

Analysis of single-cell differences by use of an on-chip microculture system and optical trapping

A method is described for continuous observation of isolated single cells that enables genetically identical cells to be compared; it uses an on-chip microculture system and optical tweezers. Photolithography is used to construct microchambers with 5-microm-high walls made of thick photoresist (SU-8) on the surface of a glass slide. These microchambers are connected by a channel through which cells are transported, by means of optical tweezers, from a cultivation microchamber to an analysis microchamber, or from the analysis microchamber to a waste microchamber. The microchambers are covered with a semi-permeable membrane to separate them from nutrient medium circulating through a "cover chamber" above. Differential analysis of isolated direct descendants of single cells showed that this system could be used to compare genetically identical cells under contamination-free conditions. It should thus help in the clarification of heterogeneous phenomena, for example unequal cell division and cell differentiation.