A novel synthesis of 8-arylaminotheophyllines

A novel synthesis of 8-arylaminotheophyllines ( 8a-e ) by the reaction of 5-arylazo-6-ethoxy-methyleneamino-1,3-dimethyluracils ( 2a-e ) or 5-arylazo-1,3-dimethyl-6-dimethylaminomethylene-aminouracils ( 3a-e ) with sodium dithionite in formic acid is described.     

On some variational problems for 2-dimensional Hermitian metrics

Summary Let (M, J, g) be a compact complex 2-dimensional Hermitian manifold with the Kähler form , and the torsion 1-form defined by d = . In this note we obtain the Euler-Lagrange equations for the variational functionals defined by ² and d², whereg runs in the space of all the Hermitian metrics onM. In the first case, the extremals are precisely the Kähler metrics [Gd]. In the second case, we also write down a formula for the second variation.Communicated by J. Szenthe     

VACUUM-ULTRAVIOLET PHOTOACOUSTIC SPECTROSCOPY OF BIOLOGICAL MATERIALS USING SYNCHROTRON RADIATION AS A LIGHT SOURCE

Abstract— Photoacoustic measurements of biological materials such as DNA, lysozyme, squalene and yeast cells were performed for the first time in the vacuum-UV region above 150 nm using the gas-microphone technique and synchrotron radiation as a light source. The samples studied were in a form of thin film supported on a self-supporting collodion film. The results obtained for the phase of the photoacoustic signal were found consistent with the predictions from the simple one-dimensional theory. The signal amplitudes obtained as a function of the incident wavelength were interpreted as giving the absorptance (the fraction of the incident photon energy dissipated in the sample) spectrum.     

Superhydrophobic and lipophobic properties of self-organized honeycomb and pincushion structures

This report describes the simple preparation of superhydrophobic and lipophobic surfaces by self-organization. Microporous polymer films of a fluorinated polymer with hexagonally arranged pores were prepared by casting from solution under humid conditions. Hexagonally packed water microdroplets were formed by evaporative cooling on the surface of the casting solution. After solvent evaporation, a honeycomb-patterned polymer film was formed with the water droplet array acting as a template; the water droplets themselves evaporated soon after the solvent. Two porous polymer layers were stacked vertically, separated by pillars at the hexagon vertexes. After peeling off the top layer using adhesive tape, a pincushion-like structure was obtained. Here, we show that superhydrophobic behavior was achieved, with the maximum contact angle, 170 degrees, observed using these pincushion structures. Theoretical calculations fit the experimental results well. The lipophobic properties of the films are also discussed.     

Stretching of single DNA molecules complexed with restriction endonuclease by Langmuir-Blodgett method

We have proposed a new technique for stretching single double-stranded DNA molecules on solid substrates by the Langmuir–Blodgett (LB) method. The polyion complex monolayer of a cationic amphiphile and DNA molecules formed at the air–water interface was transferred on a clean glass substrate. Vertical lifting up of the glass substrate provided the transferred monolayer consisting the stretched individual DNA molecules aligned parallel to the lifting direction on the glass. The DNA molecules complexed with the restriction endonuclease (EcoRI) were employed for stretching by using this method. Fluorescence images of the transferred monolayer showed that the EcoRI-binding DNA molecules could be stretched and immobilized on the glass substrate. A specific sequence of DNA recognized by EcoRI was detected as spatial positions of the stretched DNA molecules.     

The Bott obstruction to the existence of nice polarizations

In this note, we prove and discuss the following theorem: if the symplectic or almost symplectic manifoldM admits a nice polarizationF with dim , we must have Chern ^q M=0 and Pont ^q M=0, forq>2n–k, and, in particular, the Euler class ofM vanishes.     

Geometric quantization on presymplectic manifolds

In this paper, we discuss the possibilities of adapting geometric quantization to presymplectic manifolds, i.e., differentiable manifoldsM ^2n+k (k>0) endowed with a closed 2-form ω of rank2n. We show that such an adaptation is possible in various manners, and that, as a general idea, it reduces the quantization onM to quantization on the symplectic quotientM/V, whereV is the foliation defined by the annihilator of ω.     

Asymmetry of Monomer Unit Arrangements in Multicomponent Polymers

The concept of “flux” is proposed for quantitatively describing the manner in which the relative concentrations of three chain ends remain at a steady state in a terpolymerization. The flux is a measure of the net rate of transition from one chain end to another. If a terpolymerization remains at a steady state with respect to the relative concentrations of the three chain ends, then the flux must be either zero or some finite number which is independent of the choice of chain ends used to calculate it. It is a necessary and sufficient condition for Ham's concept of sequence reversibility to be true that the flux be zero. The flux calculated for many systems using reactivity ratio data is quite near zero. However, the calculations necessarily share the imprecision of reactivity ratio data. Ter-polymer sequence distribution data, if available, could be used in a proposed method of calculating flux.     

Rare direct imidation of aromatic metallacycle by reaction of CpCo(dithiolene) complex with N-halosuccinimide

The aromatic [CpCo(S₂C₂(R)(H))] (R = Ph, Me, 9-phenanthryl, H) complexes reacted with N-halosuccinimides (NXS; X = Cl, Br, I) in carbon tetrachloride at room temperature to undergo the N-succinimide substitution reaction on the dithiolene ring, but no halogenated dithiolene complex was obtained. The imidation products [CpCo(S₂C₂(R)(N-sccinimide))] were yielded up to 64% where X = I and R = 9-phenanthryl. The reaction of [CpCo(S₂C₂(Ph)(H))] with N-bromophthalimide (NBP) also gave the imidation product [CpCo(S₂C₂(Ph)(N-phthalimide))]. This is the rare direct imidation reaction to an aromatic metallacycle by NXS. The reaction of [CpCo(S₂C₂H₂)] (R = H) with NIS afforded the double imidation product. One by-product in this reaction was the dithiolene-dithiolene homo-coupling product [CpCo(S₂C₂(R))]₂ (R = Ph, Me, 9-phenanthryl). The microwave-enhanced (MW) reactions were attempted in the carbon tetrachloride solution. Although the solution temperature increased up to only 43 °C by MW irradiation, the imidation reaction worked with short reaction time.     

Copolymerization with depropagation. III. Composition and sequence distribution from probability considerations

Elementary probability considerations have been used to derive completely general equations which describe both the sequence distributions and compositions to be expected for copolymerizations which follow kinetic models having complete reversibility for all propagation steps. It is shown that previously derived composition equations for both reversible and irreversible systems are special cases of the general equations derived herein.