Identifying multiquark hadrons from heavy ion collisions

Identifying hadronic molecular states and/or hadrons with multiquark components either with or without exotic quantum numbers is a long-standing challenge in hadronic physics. We suggest that studying the production of these hadrons in relativistic heavy ion collisions offers a promising resolution to this problem as yields of exotic hadrons are expected to be strongly affected by their structures. Using the coalescence model for hadron production, we find that, compared to the case of a nonexotic hadron with normal quark numbers, the yield of an exotic hadron is typically an order of magnitude smaller when it is a compact multiquark state and a factor of 2 or more larger when it is a loosely bound hadronic molecule. We further find that some of the newly proposed heavy exotic states could be produced and realistically measured in these experiments.     

Non-Gaussian fluctuations resulting from power-law trapping in a lipid bilayer

Anomalous diffusion in lipid bilayers is usually attributed to viscoelastic behavior. We compute the scaling exponent of relative fluctuations of the time-averaged mean square displacement in a lipid bilayer, by using a molecular dynamics simulation. According to the continuous time random walk theory, this exponent indicates non-Gaussian behavior caused by a power-law trapping time. Our results provide the first evidence that a lipid bilayer has not only viscoelastic properties but also trapping times distributed according to a power law.     

Artificial photosynthesis by using chloroplasts from spinach adsorbed on a nanocrystalline TiO2 electrode for photovoltaic conversion

Photovoltaic conversion has been achieved by use of chloroplasts (photosynthetic organs) from spinach adsorbed on a nanocrystalline TiO₂ film on an indium tin oxide (ITO) glass electrode (chloroplast/TiO₂ electrode). The shape of the absorption spectrum of the chloroplast/TiO₂ electrode is almost the same that of a dispersion of the chloroplasts. Absorption maxima of the chloroplast/TiO₂ electrode observed at 430, 475, and 670 nm were attributed to carotenoid and chlorophyll molecules, suggesting that chloroplasts have been adsorbed by the nanocrystalline TiO₂ film on the ITO electrode. The photocurrent responses of chloroplast/TiO₂ electrodes were measured by using a solution of 0.1 M tetrabutylammonium hexafluorophosphate in acetonitrile as redox electrolyte in the presence or absence of water and 100 mW cm^?2 irradiation. The photocurrent of the chloroplast/TiO₂ electrode was increased by adding water to the redox electrolyte. The photocurrent responses of chloroplast/TiO₂ electrodes irradiated with monochromatic light (680 nm, the absorption band of photosystem II complexed with evolved oxygen) were measured by use of a solution of 0.1 M tetrabutylammonium hexafluorophosphate in acetonitrile as redox electrolyte in the presence or absence of water. A chloroplast/TiO₂ electrode photocurrent was observed only when the redox electrolyte containing water was used, indicating that the oxygen evolved from water by photosystem II in chloroplasts adsorbed by a nanocrystalline TiO₂ film on an ITO electrode irradiated at 680 nm is reduced to water by the catalytic activity of the platinum electrode. The maximum incident photon-to-current conversion efficiency (IPCE) was 0.8 % on irradiation at 670 nm.     

Mitsunobu Reactions for the Synthesis of Carbocyclic Analogues of Nucleosides: Examination of the Regioselectivity1

In order to provide a general synthetic method for carbocyclic nucleosides, regioselectivities in Mitsunobu reaction of purine, pyrimidin-2-one and their substituted derivatives with a variety of alcohols were examined and found to depend upon both substituents of the bases and kind of the alcohols.     

Genetic basis for the lack of N-glycolylneuraminic acid expression in human tissues and its implication to human evolution

Sialic acid is a family of acidic monosaccharides and consists of over 30 derivatives. Two major derivatives are N-acetylneuraminic acid (NeuAc) and N-glycolylneuraminic acid (NeuGc), and the hydroxylation of CMP-NeuAc is the rate limiting reaction for the production of NeuGc. The hydroxylation was carried out by a complex formed with hydroxylase, cytochrome b5, and NADH-cytochrome b5 reductase. Mouse hydroxylase was purified from the cytosolic fraction of the liver and its cDNA was cloned. Normal human tissues do not contain NeuGc. Human hydroxylase cDNA was also cloned and the sequence revealed that human hydroxylase has 92 bp deletion. The deletion is the cause of defective expression of NeuGc in human. Chimpanzee has intact hydroxylase gene and the 92 bp deletion occurred after the divergence of human ancestor from chimpanzee ancestor. Biochemical and molecular biological studies on the biosynthesis of NeuGc and biological functions of NeuGc are reviewed.     

Insoluble polystyrenes containing amide moieties and N-alkylated nylon-66 as phase transfer catalysts

Insoluble polystrenes containing formamide and acetamide moieties were prepared by free radical terpolymerization of the corresponding vinyl monomers, styrene, and divinylbenzene. These polymers served as phase transfer catalysts for the reaction of n-octyl bromide with potassium thiocyanate in toluene–water system. The activity of these catalysts was affected by some factors such as stirring speed particle size, and degree of crosslinking. The activity also depended strongly on the structure of active site, copolymer composition, and spacer length which cause the difference in the adsorption of potassium ion and in the microenvironment around the active site. Furthermore, nylon-66 was found to display the activity for phase transfer reactions, and the activity was remarkably increased by replacing the amide hydrogen with an alkyl group.     

Studies on pyrazines. 19 . A novel formation of alkenynylpyrazines in palladium-catalyzed reaction of 2-chloropyrazine and its N-oxide with acetylenes

Reaction of 3-chloropyrazine 1 -oxide ( 1 ) with 1-hexyne ( 2a ) in the presence of tetrakis(triphenylphosphine)-palladium(O) and potassium acetate in DMF afforded 3-(1-hexynyl)pyrazine 1 -oxide ( 3a ) and 3-(2-butyl-1-octen-3-ynyl)pyrazine 1-oxide ( 4a ). The novel formation of 4a was elucidated to result from codimerization of 3a with 2a . The details of reaction are discussed on the basis of findings in palladium(O)-catalyzed reaction of other chloroheterocycles.