Dimethyl Dihydroacridines as Photocatalysts in Organocatalyzed Atom Transfer Radical Polymerization of Acrylate Monomers

Development of photocatalysts (PCs) with diverse properties has been essential in the advancement of organocatalyzed atom transfer radical polymerization (O‐ATRP). Dimethyl dihydroacridines are presented here as a new family of organic PCs, for the first time enabling controlled polymerization of challenging acrylate monomers by O‐ATRP. Structure–property relationships for seven PCs are established, demonstrating tunable photochemical and electrochemical properties, and accessing a strongly oxidizing ²PC^.+ intermediate for efficient deactivation. In O‐ATRP, the combination of PC, implementation of continuous‐flow reactors, and promotion of deactivation through addition of LiBr are critical to producing well‐defined acrylate polymers with dispersities as low as 1.12. The utility of this approach is established through demonstration of the oxygen‐tolerance of the system and application to diverse acrylate monomers, including the synthesis of well‐defined di‐ and triblock copolymers.     

Novel hybrid vesicles co-assembled from a cationic lipid and PAAc-g-mPEG with pH-triggered transmembrane channels for controlled drug release

This work presents an important example of novel hybrid vesicles with pH-triggered transmembrane channels prepared by co-assembly of poly(acrylic acid)-g-poly(monomethoxy ethylene glycol) (PAAc-g-mPEG) with a cationic lipid, didodecyldimethylammonium bromide (DDAB), via electrostatic interaction for effective doxorubicin (DOX) release.     

Spin superstructure and noncoplanar ordering in metallic pyrochlore magnets with degenerate orbitals

We study double-exchange models with itinerant t(2g) electrons in spinel and pyrochlore crystals. In both cases the localized spins form a network of corner-sharing tetrahedra. We show that the strong directional dependence of t(2g) orbitals leads to unusual Fermi surfaces that induce spin superstructures and noncoplanar orderings for a weak coupling between itinerant electrons and localized spins. Implications of our results to ZnV(2)O(4) and Cd(2)Os(2)O(7) are also discussed.     

Mayer function perturbation theory of effective interaction of charged colloids

In this paper, the effective interaction between charged colloids has been studied based on the standard Mayer function perturbation theory. With the formalism developed in this paper, the effective interaction as a function of Mayer functions and the correlation functions of the homogeneous microions is obtained. The asymptotic behaviour of the effective interaction at large distance is analysed in detail. It is found that at large distance the effective interaction is Yukawa like, provided the bare charge is replaced by the renormalised one. Exact expressions for the renormalised charge and the decay length as functions of the short-range part of the Mayer function and that of the correlation function of the homogeneous microions are obtained. With perturbation methods, it is easy to see how the effective interaction at large distance is affected by microion correlations and nonlinearity.     

Design of a wedge plate for polarization-preserving angular shifter

It is shown that by using a wedge plate, the incident direction of light propagation can be rotated as necessary while still preserving beam polarization. The basic conditions of these preservations of polarization are deduced. For numerical demonstration, it is shown that a collimated beam with +45° linear polarization can be guided to any pre-settled direction where the square of ellipse ratio variation in the polarization is less than 0.0001%, while the variation of squared ellipse ratio of a right circular polarization beam is kept under 0.1%.     

Uniqueness and structure of solutions to the Dirichlet problem for an elliptic system

In this paper, we consider the Dirichlet problem for an elliptic system on a ball in R². By investigating the properties for the corresponding linearized equations of solutions, and adopting the Pohozaev identity and Implicit Function Theorem, we show the uniqueness and the structure of solutions.     

Asymptotic behavior of equilibrium states of reaction–diffusion systems with mass conservation

We deal with a stationary problem of a reaction–diffusion system with a conservation law under the Neumann boundary condition. It is shown that the stationary problem turns to be the Euler–Lagrange equation of an energy functional with a mass constraint. When the domain is the finite interval $(0,1)$, we investigate the asymptotic profile of a strictly monotone minimizer of the energy as d, the ratio of the diffusion coefficient of the system, tends to zero. In view of a logarithmic function in the leading term of the potential, we get to a scaling parameter κ satisfying the relation $\epsilon :=\sqrt{d}=\sqrt{\log ?\kappa }/{\kappa }^2$. The main result shows that a sequence of minimizers converges to a Dirac mass multiplied by the total mass and that by a scaling with κ the asymptotic profile exhibits a parabola in the nonvanishing region. We also prove the existence of an unstable monotone solution when the mass is small.     

Reactions of Nadic Anhydride at High Temperatures

The reaction of nadic anhydride(NA) at high temperature under oxygen or oxygen-free conditions was investigated in this report in order to understand the cross-linking behavior of nadic end-capped polyimides. In this study, ¹³C-NMR, mass spectra as well as IR spectroscopy were employed for understanding the reactions involved. In ampule tests, NA was heated after sealing in air or under nitrogen, The dimer, trimer and tetramer of NA were found when heated at 260°C for 30 min. and their possible chemical linkage is shown. More complicated products could be obtained when heating For longer time. The cleavage of double bond was observed when NA was heated at about 340°C and the linkage containing oxygen was found when scaled in air. The molecular weight of product increased in this case.