Specific adenine alkylation by pyrrole-imidazole CBI conjugates

We examined DNA alkylation by pyrrole (Py)-imidazole (Im) hairpin polyamides, which possess 1,2,9,9a-tetrahydrocyclopropa[1,2-c]benz[1,2-e]indol-4-one (CBI) or cyclopropapyrroloindole (CPI) as DNA alkylating moieties. High-resolution denaturing gel electrophoresis revealed that alkylation by CBI conjugates 2 and 4 occurred specifically at adenines (A) in matched sequences, whereas CPI conjugates 1 and 3 alkylated both A and guanines (G) in matched sequences. The origin of the different reactivity of CBI and CPI conjugates is discussed in relation to the electrophilicity of the cyclopropane moiety. The high selectivity of the CBI conjugate gives additional sequence specificity relative to CPI conjugates that would be useful for the biological applications.     

The effect of gas injection on a thermal argon plasma flow in a water-cooled tube

The effect of gas injection on an atmospheric thermal argon plasma flow in a water-cooled tube was investigated experimentally and numerically. The injection gas is argon, helium, or nitrogen. The static pressure with helium injection increases greatly because of its high thermal conductivity, while little increase occurs for nitrogen injection because of the dissociation. The increasing rate of the static pressure depends on the ratio of the momentum term to the viscosity term. The heat flux to the tube wall with gas injection changes less than that without injection. The numerical results showed variations similar to the experimental ones.     

Novel A-seco-rearranged lanostane triterpenoids from Abies sachalinensis

From the needles of Abies sachalinensis, novel rearranged lanostane type triterpenes, 1-4, were isolated along with a known triterpene (5). The structures of the new compounds, 1-4, were elucidated to be 3,4-seco-8-(14-->13R)abeo-17,13-friedo-9beta-lanosta-4(28),7,14(30),22Z,24-pentaen-26,23-olide-3-oic acid, methyl 3,4-seco-8-(14-->13R)abeo-17,13-friedo-9beta-lanosta-4(28),7,14(30),22Z,24-penten-26,23-olide-3-oate, 3,4-seco-8(14-->13R)abeo-17,13-friedo-9beta-lanosta-4(28),7,14,22Z,24-pentaene-26,23-olide-3-oic acid and methyl 3,4-seco-8(14-->13R)abeo-17,13-friedo-9beta-lanosta-4(28),7,14,22Z,24-pentaene-26,23-olide-3-oate, respectively, by means of spectral experiments, especially two dimensional NMR spectroscopy, such as 1H-detected multiple quantum coherence (HMQC), 1H-detected heteronuclear multiple bond connectivity (HMBC) and 1H-1H-correlation spectroscopy (COSY) experiments. These new compounds have novel structures containing A-seco, rearranged spiro structure and a gamma-lactone conjugated with a diene. Some of these compounds showed potent antibacterial activity against gram positive bacteria.     

GalnAsP-InP double-heterostructure lasers

GaInAsP-InP double-heterostructure lasers which are the most promising optical sources for the long wavelength region have been investigated. In the crystal growth, it was found that the liquidus and solidus isotherms are affected by the orientation of InP source and substrate crystals in the liquid phase epitaxial growth of GaInAsP alloys. The unit cell of the GaInAsP epitaxial layer is tetragonally deformed due to the interface lattice misfit such that the lattice constant parallel to the wafer surface is invariant across the interfaces in the GaInAsP-InP wafers. Two kinds of stripe lasers, planar stripe and buried lasers, have been fabricated by use of GaInAsP cap layer for good p-type contact. The planar stripe lasers of 10,15 and 20 m wide stripe operated in fundamental-transverse mode with 20–30% differential external efficiencies per facet. The 15 m wide stripe laser showed good mode characteristics to operate in a fundamental-transverse mode up to the cw output power of 22 mW per facet and in a single longitudinal mode over a wide range of currents. The buried stripe laser operated in a fundamental-transverse mode with the threshold current as low as 30 mA by making the stripe width narrower than 2 (m. The laser succeeded in cw operation at 100 °C because of its low threshold current and low thermal resistance.The authors would like to thank K. Noda, N. Kuroyanagi and Y. Furukawa for their encouragement. Thanks are also due to H. Kano for permission to use his results of buried stripe lasers prior to publication, and S. Ando for his technical assistance.     

Simultaneous liquid chromatographic determination of 39 polycyclic aromatic hydrocarbons in indoor and outdoor air and application to a survey on indoor air pollution in Fuji, Japan

An analytical method was established for the simultaneous determination of 39 polycyclic aromatic hydrocarbons (PAHs) in air. The method was applied to a survey of gaseous and particulate PAHs in household indoor air. The survey was performed in 21 houses in the summer of 1999 and in 20 houses in the winter of 1999-2000 in Fuji, Japan. Thirty-eight PAHs were determined in indoor and outdoor air in the summer, and 39 PAHs were determined in indoor and outdoor air in the winter. The concentrations of gaseous PAHs in indoor air tended to be higher than those in outdoor air in the summer and winter. The concentrations of particulate PAHs in indoor air were the same as or lower than those in outdoor air in the summer and winter. PAH profiles, correlations between PAH concentrations, and multiple regression analysis were used to determine the factors affecting the indoor PAH concentrations. These results showed that gaseous PAHs in indoor air were primarily from indoor emission sources, especially during the summer, and that indoor particulate PAH concentrations were significantly influenced by outdoor air pollution.     

Synthesis of isoxazolo[2,3-a]quinoxalines and pyrrolo[1,2-a]quinoxalines by 1,3-dipolar cycloaddition reaction

The isoxazolo[2,3-a]quinoxalines 11a,b and pyrrolo[1,2-a]quinoxalines 12a,b were selectively synthesized from the 2-substituted 6-chloroquinoxaline 4-oxides 10a,b . The pyrrolo[1,2-a]quinoxalines 12a,b were clarified to be produced by the ring transformation of the isoxazolo[2,3-a]quinoxalines 11a,b . The pyrrolo[1,2-a]quinoxalines 14a,b were obtained from both 2,6-dichloroquinoxaline 4-oxide 9 and compounds 12a,b .     

Formation of a new crystalline silicate structure by grafting dialkoxysilyl groups on layered octosilicate

Dialkoxydichlorosilanes ((RO)2SiCl2, R = alkyl) react almost completely with interlayer silanol groups in a layered silicate octosilicate to create a new crystalline silicate structure consisting of new five-membered rings arranged regularly on both sides of the silicate layers. The introduction of dialkoxysilyl groups to the interlamellar region of layered silicates with regular reaction sites provides a new methodology for the design and construction of novel crystalline silicate frameworks by a soft chemical route.     

Synthesis of enantiopure 1,2-diamine attached to cross-linked polystyrene and its application to an insoluble catalyst for asymmetric hydrogenation

A novel enantiopure 1,2-diamine (5) having two phenolic hydroxy groups was attached into chloromethylated polystyrene through benzyl ether linkage, which was used as a chiral ligand of the catalyst in asymmetric hydrogenation of acetophenone.     

Effects of ortho-substituents on reactivities,tacticities, and ceiling temperatures of radical polymerizations of phenyl methacrylates

Radical polymerization and copolymerization of some o-alkylphenyl methacrylates were carried out and the effect of the ortho-substituents on the ability to homopolymerize, on the monomer reactivities, and on the ceiling temperatures of the monomers was studied. The effect of the substituent on tacticities and thermal stabilities of the polymers formed was also discussed. The ability to honiopolymerize and the monomer reactivity were considerably decreased by the introduction of the o-substituent. 2,6-Di-tert-butylphenyl methacrylate formed no methanol-insoluble polymer at 60°C. On the basis of the tacticity determined it was noted that the o-substituted phenyl methacrylates preferred syndiotactic addition in the propagation reaction less than did phenyl methacrylate or methyl methacrylate. The polymers formed from the o-substituted monomers were thermally less stable than poly(phenyl methacrylate), and, consistent with this finding, ceiling temperatures of the o-substituted phenyl methacrylates seemed to be lower than that of phenyl methacrylate. The effects observed were characteristic of the o-substituents conformationally close to the carbon-carbon double bond of the monomer or the carbon carrying the unpaired electron of the polymer radical.     

The molecular structure and chemical reactivities of the condensation products of o-substituted benzylidenacetylacetone with hydrazine dihydrochloride

Reaction of o-nitrobenzylideneacetylacetone ( 1a ) with hydrazine dihydrochloride in methanol gave 4-(α-methoxy-o-nitrobenzyl)-3,5-dimethylpyrazole hydrochloride ( 4a ), whose structure was unambigously confirmed by an X-ray crystallographic analysis, via 4-(o-nitrobenzylidene)-3,5-dimethylisopyrazole ( 2a ). Compound 2a was synthesized by condensation of 1a with hydrazine dihydrochloride in acetonitrile. Analogously the corresponding o-chloro derivatives ( 2b, 4b ) were obtained. These were converted to N-methyl ( 6b ) and N-acetyl ( 7a,b ) derivatives and the behaviors on bromination and pyrolysis were investigated.