Formation of a symmetric vortex configuration in a pure electron plasma trapped with a penning trap

In the formation of vortical crystal structures of electrons, the distribution of background electrons works as a “cooler” of randomly moving, intense vortices. We examine the supporting effect of background electrons to forming crystal structures from the perspective of a reduction of the vortices’ random motion.     

A New Concept for an Alkaline Developable Positive‐Tone Resist: Molecular Resist Utilizing Acid Catalyzed Isomerization from Oxabenzonorbornadiene to Naphthol

A novel positive‐tone molecular resist possessing oxabenzonorbornadiene moiety was developed for electron‐beam (EB) lithography. The synthesized resist material showed relatively high glass transition temperature and readily formed uniform amorphous films on a silicon wafer. The sensitivity of an EB resist was ca. 8 µC · cm⁻² and line and space patterns of 200 nm could be fabricated. The promising feature of the resist materials is that no outgassed products from base matrixes are theoretically produced under the exposure and post‐exposure bake procedure.

     

Asymmetric cyclopolymerization of N‐tert‐butyl‐N‐allylacrylamide in the presence of β‐cyclodextrin

The radical polymerization of N‐tert‐butyl‐N‐allylacrylamide (t‐BAA) was carried out in a dimethyl sulfoxide/H₂O mixture in the presence of β‐cyclodextrin (β‐CD). The polymerization proceeded with the complete cyclization of the t‐BAA unit and yielded optically active poly(t‐BAA). The IR spectrum of the obtained polymer showed that the cyclic structure in the polymer was a five‐membered ring. The optical activity of poly(t‐BAA) increased with an increasing molar ratio of β‐CD to the t‐BAA monomer. The interaction of β‐CD with t‐BAA was confirmed by ¹H NMR and ¹³C NMR analyses of the polymerization system. It is suggested that interaction of the t‐BAA monomer with the hydrophobic cavity of β‐CD plays an important role in the asymmetric cyclopolymerization of t‐BAA. The radical copolymerization of t‐BAA with styrene (St), methyl methacrylate, ethyl methacrylate, or benzyl methacrylate (BMA) also produced optically active copolymers with a cyclic structure from the t‐BAA unit. St and BMA carrying a phenyl group were predicted to compete with t‐BAA for interaction with β‐CD in the copolymerization system. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2098–2105, 2000     

Novel Molecular Resist Based on a First Generation Dendrimer Possessing Furan Rings

Summary: A novel chemically amplified negative‐tone molecular resist for electron‐beam (EB) lithography was developed. The base matrix had six furan rings as a reactive functional group at its terminal. The resist containing the matrix, a crosslinker and a photoacid generator worked well as a negative‐tone resist with high sensitivity (3 µC · cm⁻²). Line and space patterns (1:2) of 200 nm could be fabricated.

SEM image of negative‐tone line and space patterns for the resist film formulated with G1‐dendrimer 5 .     

Development and characterization of a DNA solar dosimeter

In this paper, we report the development and characterization of a solar ultraviolet (UV) dosimetry system that can be used as a film badge for radiation monitoring. DNA molecules are coated on a thin nylon membrane as a UV dosimeter. The membrane is sealed in a polyethylene filter envelope with silica gel to keep the humidity low. After exposure to UV or solar light, induced DNA damage is measured by an immunochemical reaction. The intensity of color developed during the immunological reaction can be correlated linearly with the irradiated UV dose delivered by an Oriel solar simulator within a limited dose range. We observe no effects of temperature on the level of damage induction. The membrane is proficient for measuring DNA damage for more than 21 days when stored at either 37 or 4°C. The induced damage remains stable on the membrane for at least 22 days at both 37 and 4°C. In addition to these indoor experiments, we report measurements of solar UV dose in outdoor experiments.     

Structural Analysis and Inclusion Mechanism of Native and Permethylated α‐Cyclodextrin‐Based Rotaxanes Containing Alkylene Axles

Native α‐cyclodextrin‐ (α‐CD) and permethylated α‐CD (PMeCD)‐based rotaxanes with various short alkylene chains as axles can be synthesized through a urea end‐capping method. Native α‐CD tends to form [3]‐ or [5]pseudorotaxanes and not [2]‐ or [4]pseudorotaxanes, which indicates that the coupled CDs act as a single fragment. End‐capping reactions of the pseudorotaxanes with C18 and C24 axle lengths do not occur because the axle termini are covered by the densely stacked CDs. The number of PMeCDs on the pseudorotaxane is flexible and mainly depends on the axle length. Peracetylated α‐CD (PAcCD)‐based rotaxanes are synthesized through O‐acetylation of the α‐CD‐based rotaxanes without any decomposition of the rotaxanated structures. The structures of PMeCD‐based [3]‐ and [4]rotaxanes, and the molecular dynamics calculations on [3]pseudorotaxanes, indicate that the tail face of PMeCDs is regularly directed toward the axle termini. On the basis of the results obtained, it can be concluded that the directions and numbers of CDs in rotaxanes containing short alkylene chains depend on 1) the interactions between CDs, 2) the length of the alkylene axle, and 3) the interactions between the axle end and tail face of the CD.     

Classification of bifurcation diagrams for elliptic equations with exponential growth in a ball

Annali di Matematica Pura ed Applicata (1923 -) - Let $$B\subset \mathbb {R}^N$$ , $$N\ge 3$$ , be the unit ball. We study the global bifurcation diagram of the solutions of $$\begin{aligned}...