Dual‐responsive supramolecular inclusion complexes of block copolymer poly(ethylene glycol)‐block‐poly[(2‐dimethylamino)ethyl methacrylate] with α‐cyclodextrin

A new class of temperature and pH dual‐responsive and injectable supramolecular hydrogel was developed, which was formed from block copolymer poly(ethylene glycol)‐block‐poly[(2‐dimethylamino)ethyl methacrylate] (PEG‐b‐PDMAEMA) and α‐cyclodextrin (α‐CD) inclusion complexes (ICs). The PEG‐b‐PDMAEMA diblock copolymers with different ratio of ethylene glycol (EG) to (2‐dimethylamino)ethyl methacrylate (DMAEMA) (102:46 and 102:96, respectively) were prepared by atom transfer radical polymerization (ATRP). ¹H NMR measurement indicated that the ratio of EG unit to α‐CD in the resulted ICs was higher than 2:1. Thermal analysis showed that thermal stability of ICs was improved. The rheology studies showed that the hydrogels were temperature and pH sensitive. Moreover, the hydrogels were thixotropic and reversible. The self‐assembly morphologies of the ICs in different pH and ionic strength environment were studied by transmission electron microscopy. The formed biocompatible micelles have potential applications as biomedical and stimulus‐responsive material. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2143–2153, 2010     

Breathing Pores on Command: Redox‐Responsive Spongy Membranes from Poly(ferrocenylsilane)s

Redox‐responsive porous membranes can be readily formed by electrostatic complexation between redox active poly(ferrocenylsilane) PFS‐based poly(ionic liquid)s and organic acids. Redox‐induced changes on this membrane demonstrated reversible switching between more open and more closed porous structures. By taking advantage of the structure changes in the oxidized and reduced states, the porous membrane exhibits reversible permeability control and shows great potential in gated filtration, catalysis, and controlled release.     

Robust output feedback time optimal decomposed controllers for linear systems via moving horizon estimation

This paper studies the robust output feedback time optimal control (TOC) problem for linear discrete-time systems with state and input constraints. Bounded state disturbances are assumed. The moving horizon estimation (MHE) technique combined with a Luenberger observer is used to design a state estimator with which the state estimation error converges to and remains in some disturbance invariant set. A novel approach is proposed to reduce the computational complexity of TOC, in which the terminal controller comprises several predetermined local linear feedback laws, resulting in a large terminal set. Starting from this relatively large terminal set, a large domain of attraction of the proposed TOC controller can be obtained by using a short horizon, which consequently leads to a low on-line computational effort. A correction term, the output of the observer subtracted from the output of the plant and then multiplied by a design matrix, is added to the TOC controller, which aims at further correcting estimates of the state based on the present estimation error. Furthermore, by formulating a suitable cost function, as time evolves the TOC controller reaches the desired controller to obtain a good asymptotical behavior. A case study is used to illustrate the proposed approach.     

Large Magnetocaloric Effect in a Dense and Stable Inorganic–Organic Hybrid Cobridged by In Situ Generated Sulfate and Oxalate

A dense and stable inorganic‐organic hybrid with distorted cubic [Gd₄O₄] units as building blocks bridged by in situ generated sulfate and oxalate was synthesized. Magnetic measurements indicate that the title complex features a ?ΔS_m^max=51.49 J kg^?1 K^?1, which is among the highest values reported so far.     

One-dimensional alkylate-bridged Würster's blue-based diradical dications

By using weakly coordinating anions we succeeded in the stabilization and isolation of two Würster's blue-based diradicaloid dications with saturated spacers. Their geometries and electronic structures were investigated by various experiments in conjunction with DFT calculations. Both one-dimensional alkylate-bridged dications show considerable diradical character with spacer-dependent singlet-triplet energy gaps. One of them displays a much enhanced diradical character and could basically be viewed as a pure diradical with degeneracy of singlet and triplet states.     

Hexylene- and octylene-bridged polysilsesquioxane hybrid crystals self-assembled by dimeric building blocks with ring structures

We report the synthesis of novel polysilsesquioxane hybrid crystals prepared from two precursors with hexylene- and octylene-bridged groups. Both crystals are composed of bimolecular rings (18- and 22-membered, respectively) formed by one-step condensation of two hydrolyzed monomers. The hydrogen bonds between silanol groups and the weak van der Waal's interactions between alkyl chains link the large rings as building blocks together into self-assembled, three-dimensional molecular crystalline structures. The precise control of the sol-gel process is considered to be the crucial factor in fabricating flexible long alkyl chains into an ordered stacking. These contributions extend the understanding of the sol-gel chemistry of polysilsesquioxanes.     

Determination of Armillarisin A in Rat Plasma by SPE and LC-MS-MS

A rapid, sensitive and convenient ultra-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the determination of armillarisin A in rat plasma. Following hydrophilic–lipophilic balance solid-phase extraction, armillarisin A and propylparaben (internal standard) were separated using a gradient elution program on a C₁₈ column and detected by mass spectrometry in the negative ion mode with the multiple reaction monitoring mode. The total chromatographic running time was short (1.8 min). The method was linear over the concentration range of 0.5–250.00 ng mL^?1 for armillarisin A. The lower limit of quantification of armillarisin A was 0.5 ng mL^?1, using as little as 100 μL plasma. The intra-day and inter-day relative standard deviations were less than 15% and the relative errors were all within 10%. The extraction recovery for armillarisin A was approximately 100%, and no absolute matrix effect was observed. Finally, the method was successfully applied to a preclinical pharmacokinetic study of armillarisin A in four rats following an intravenous administration.     

Novel application of 1-/2-phenyl substituted 9,10-anthraquinones in solid electrochromic devices

1-/2-phenyl substituted 9,10-anthraquinones were synthesized via Suzuki coupling reactions of 1-/2-iodo-9,10-anthraquinones with benzeneboronic acid. They are efficient and reversible electrochromic materials and their solid electrochromic devices were prepared. When reduced, the device color of 1-phenyl-9,10-anthraquinone shifts from yellow to claret while that of 2-phenyl-9,10-anthraquinone switches from yellow-green to a dark blue-purple. Their different characteristics and behaviors in electrochromic devices are only determined by the different substituted positions of the phenyl group. They are potentially to be widely applied in commercial application for the excellent behaviors plus the inexpensive starting materials and short synthetic routes.     

Extracting uniaxial anisotropy of ferromagnetic layer in exchange-biased system

Effective anisotropy of the ferromagnetic pinned layer of ferro(FM)-antiferromagnetic (AF)-coupled NiFe(FM)/FeMn(AF) exchange-biased system was investigated in a broad frequency range (100 MHz-5 GHz) using a complex permeability spectrum. The exchange bias and effective uniaxial anisotropy fields of the thin film have been computed theoretically using the Landau-Lifschitz-Gilbert (LLG) equation. From the measurements, uniaxial anisotropy of the pinned FM layer has been extracted to understand the nature of the exchange bias in the system. It is found that the uniaxial anisotropy field of NiFe layer when exchange biased with the AF layer increases from 5 to 15 Oe at different external magnetic fields.