Synthesis of pyrimidine derivatives using N-bis(methylthio)methylenecyanamide

N-Bis(methylthio)methylenecyanamide ( 1 ) was allowed to react with active methylene compounds (methyl cyanoacetate, dimethyl malonate, ethyl acetoacetate, ethyl phenylacetate) in the presence of potassium carbonate or potassium hydroxide in dimethyl sulfoxide followed by the treatment using appropriate a base or an acid to give the corresponding 6-methylthiouracil derivatives in 15–80% yields. These uracil derivatives are found to be useful intermediates for the synthesis of 6-aminouracils and fused pyrimidine derivatives.     

Fabrication of Al nanoparticles and their electrical properties studied by capacitance-voltage measurements

Nanometer-scale Al particles are fabricated and are embedded in a GaAs matrix using molecular beam epitaxial technique. The Al particle is self-assembled on GaAs by supplying an Al molecular beam. The average particle size is found to be 25 nm. The density is 7 × 10¹⁰ cm⁻² when Al of 6.2 × 10¹⁵ atoms/cm² is supplied on (1 0 0)GaAs at a substrate temperature of 300 °C. Clear hysteresis and plateaus in capacitance-voltage (C-V) curves are found in an Al-embedded sample, whereas monotonic increase of capacitance is obtained in a reference sample having an AlAs layer instead of Al. This difference results from trapping of electrons by the Al particles, suggesting that the particles have metallic character.     

Dielectric behaviour of a side-chain-bearing liquid-crystalline polysiloxane

The relaxation of electric field-induced polar orientation in a side-chain-bearing liquid-crystalline polysiloxane was measured by means of thermally stimulated depolarization currents. Different relaxation mechanisms were identified and characterized: the glass transition cooperative relaxation exhibits compensation behaviour. On the other hand, lowerT _g and upperT _g discharges were observed and their molecular nature is discussed.     

Interlaboratory study of DNA extraction from multiple ground samples, multiplex real-time PCR, and multiplex qualitative PCR for individual kernel detection system of genetically modified maize

In many countries, the labeling of grains, feed, and foodstuff is mandatory if the genetically modified (GM) organism content exceeds a certain level of approved GM varieties. We previously developed an individual kernel detection system consisting of grinding individual kernels, DNA extraction from the individually ground kernels, GM detection using multiplex real-time PCR, and GM event detection using multiplex qualitative PCR to analyze the precise commingling level and varieties of GM maize in real sample grains. We performed the interlaboratory study of the DNA extraction with multiple ground samples, multiplex real-time PCR detection, and multiplex qualitative PCR detection to evaluate its applicability, practicality, and ruggedness for the individual kernel detection system of GM maize. DNA extraction with multiple ground samples, multiplex real-time PCR, and multiplex qualitative PCR were evaluated by five laboratories in Japan, and all results from these laboratories were consistent with the expected results in terms of the commingling level and event analysis. Thus, the DNA extraction with multiple ground samples, multiplex real-time PCR, and multiplex qualitative PCR for the individual kernel detection system is applicable and practicable in a laboratory to regulate the commingling level of GM maize grain for GM samples, including stacked GM maize.     

Effective synthesis of diiodinated picene and dibenzo[a,h]anthracene by AuCl-catalyzed double cyclization

6,13-Diiododibenzo[a,h]anthracene and 5,8-diiodopicene were synthesized by AuCl-catalyzed double cyclization. The highly selective reaction yielded a new class of peri-halogenated fused aromatics.     

Dual responsive nanostructured surfaces for biomedical applications

In this paper, we describe the construction and characteristics of thermoresponsive, thin nanostructured films prepared by layer-by-layer sequential assembly of chitosan-graft-NIPAAm and alginate. FTIR and (1)H NMR spectra have confirmed the introduction of NIPAAm moieties onto the chitosan backbone. The LCST of the synthesized copolymer was found to be around 31-33 °C. The formation of the polyelectrolyte multilayers containing the copolymer and alginate was followed in situ by quartz crystal microbalance with dissipation monitoring technique and ex situ by UV-vis measurements. Our results revealed the linear increase of the multilayer film growth and the influence of the presence of salt. Moreover, AFM analysis has confirmed that PNIPAAm is able to reconform upon temperature swaps even when combined with other layers in a polyelectrolyte multilayer, demonstrating that the nanoassemblies are thermoresponsive. Preliminary results showed that, upon reducing culture temperature below PNIPAAm LCST, a gradual detachment of cell sheets from these PNIPAAm-based coatings has occurred.     

Special functions associated with a certain fourth-order differential equation

We develop a theory of “special functions” associated with a certain fourth-order differential operator D_m,n\mathcal{D}_{\mu,\nu} on ℝ depending on two parameters μ,ν. For integers μ,ν≥−1 with μ+ν∈2ℕ₀, this operator extends to a self-adjoint operator on L ²(ℝ₊,x ^μ+ν+1 dx) with discrete spectrum. We find a closed formula for the generating functions of the eigenfunctions, from which we derive basic properties of the eigenfunctions such as orthogonality, completeness, L ²-norms, integral representations, and various recurrence relations.     

Hydroxypropyl chitosan bearing beta-cyclodextrin cavities: synthesis and slow release of its inclusion complex with a model hydrophobic drug

Hydroxypropyl chitosan-graft-carboxymethyl beta-cyclodextrin (HPCH-g-CM beta-CD) was synthesized by grafting CM beta-CD onto HPCH using water soluble 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) as the condensing agent. Due to the presence of hydrophobic beta-CD rings onto the HPCH backbone, this polymer can be used as a matrix for controlled drug release. The adsorption of a hydrophobic model drug, ketoprofen, by HPCH-g-CM beta-CD microparticles (using tripolyphosphate as an ionic crosslinking agent) fitted well in the Langmuir isotherm equation. The drug dissolution profile showed that HPCH-g-CM beta-CD microparticles provided a slower release of the entrapped ketoprofen than chitosan, and the release behavior was influenced by the pH value of the medium. These results suggest that beta-CD grafted with chitosan derivatives may become a potential biodegradable delivery system to control the release of hydrophobic drugs with pH-responsive capability.     

A thermally stimulated discharge currents study of the molecular motions in two polysiloxane side-chain liquid crystalline polymers

The technique of thermally stimulated depolarization currents was used to study the dipolar relaxation mechanisms in two side-chain liquid-crystalline polysiloxanes. The studied polymers have the same mesogenic side-group, but they differ in the number (or density) of side groups attached to the main chain. In both cases three different relaxations were observed: one in the vitreous state, one in the liquid crystalline phase, and the glass transition relaxation. The features of those thermally stimulated discharges are discussed and some suggestions are made concerning the attribution of those discharges at the molecular level. © 1995 John Wiley & Sons, Inc.