Effect of reaction solvent on the preparation of thermo-responsive stationary phase through a surface initiated atom transfer radical polymerization

Poly(N-isopropylacrylamide) (PIPAAm) brush grafted silica beads, a thermo-responsive chromatographic stationary phase, were prepared through a surface-initiated atom transfer radical polymerization (ATRP) using 2-propanol, N,N-dimethylformamide (DMF), and water as reaction solvents. The rate of grafting PIPAAm on silica bead surfaces was different and found to be dependent on the reactivity of reaction solvent. Temperature-dependent elution profiles of hydrophobic steroids from the prepared-beads-packed columns were found to be different, although the graft amounts of PIPAAm were similar on silica bead surfaces. Especially, prepared beads using 2-propanol exhibited a higher resolution than those using DMF. Calibration curves using glucose and pullulan suggested that beads prepared using DMF prohibited analytes to diffuse into the pores. On the contrary, beads prepared using 2-propanol allowed analytes to diffuse into the pores. The pore diameter of the prepared beads, measured by N(2) adsorption-desorption measurement, suggested that beads using 2-propanol has relatively larger pore diameter than those using DMF. Thus, the reaction solvent in surfaces-initiated ATRP affected the grafting configuration of PIPAAm on porous silica-bead surfaces, leading to the different separation efficiency of stationary phase for bioactive compounds.     

Integrated and diffusion-based micro-injectors for open access cell assays

Currently, most microfluidic devices are fabricated with embedded micro-channels and other elements in a close form with outward connections. Although much functionality has been demonstrated and a large number of applications have been developed, they are not easy for routine operation in biology laboratories where most in vitro cell processing still relies on the use of culture dishes, glass slides, multi-well plates, tubes, pipettes, etc. We report here an open access device which consists of an array of isolated micro-channels plated on a large culture surface, each of them having tiny nozzles for localized drug delivery. In a diffusion dominant regime, steady gradients of molecule concentration could be obtained and varied by changing the flow rate inside the micro-channels. As assay examples, cell staining and drug-induced cell apoptosis were demonstrated, showing fast cell responses in close proximity of the nozzles.     

Photomechanical bending of salicylideneaniline crystals

Platelike microcrystals of N-3,5-di-tert-butylsalicylidene-3-nitroaniline repeatedly bend and straighten upon alternate irradiation with UV and visible light. The mechanism of bending was elucidated by X-ray crystallographic analyses before and after photoirradiation.     

A photochromic ATP analogue driving a motor protein with reversible light-controlled motility: controlling velocity and binding manner of a kinesin-microtubule system in an in vitro motility assay

We synthesized two photochromic ATP analogues (ATP-Azos) featuring azobenzene derivatives tethered at the 2' position of the ribose ring. In the presence of the ATP-Azo tethering p-tert-butylazobenzene, we observed reversible photo-control of the motility, velocity and binding manner, of a kinesin-microtubule system in an in vitro motility assay.     

Composite and Elementary Components in Hadron Resonances

In hadron resonances different structures of hadronic composite (molecule) and elementary (quark-intrinsic) natures may coexist. We sketch discussions based on our previous publications on the origin of hadron resonances (Hyodo et al. Phys. Rev. C 78:025203, 2008) on exotic ${\bar D (B)}$ meson–nucleons as candidates of hadronic composites (Yamaguchi et al. Phys. Rev. D 84:014032, 2011) and on a ₁ for the coexistence/mixing of the two different natures (Nagahiro et al. Phys. Rev. D 83:111504, 2011).     

Spectroscopy of η′ Mesic Nuclei with (p, d) Reaction

We are going to perform an inclusive spectroscopy experiment of η′ mesic nuclei with the ¹²C(p,d) reaction to study in-medium properties of the η′ meson. In nuclear medium, the η′ meson mass may be reduced due to partial restoration of chiral symmetry. In case of sufficiently large mass reduction and small absorption width of η′ at normal nuclear density, peak structures of η′ mesic states in ¹¹C will be observed near the η′ emission threshold even in an inclusive spectrum. The experiment will be carried out at GSI with proton beam supplied by SIS using FRS as a spectrometer. The detail of the experiment is described.     

Synthesis and Mesomorphic Properties of Ferroelectric Liquid Crystals with a Fluorinated Asymmetric Frame (1)

New ferroelectric liquid crystals with a fluorinated asymmetric frame were synthesized utilizing optically active S-(-)-2-fluoroalkanols prepared from R-(+)-1,2-epoxyalkanes with pyridinium poly(hydrogen fluoride), and their mesomorphic and physical properties (phase behavior, spontaneous polarization, response time) were studied. The biphenyl-phenyl derivatives of three-ring systems exhibited enantiotropic chiral smectic C phase in a broad temperature range (108°C-185°C). The phenyl benzoate of two-ring systems exhibited chiral smectic C phase at temperature relatively close to room temperature, and were found to possess the spontaneous polarization larger than 35 nC/cm².     

Fine Tuning of Vesicle Assembly and Properties Using Dual Hydrophilic Triblock Copolypeptides

The design, synthesis, and self‐assembly of the first dual hydrophilic triblock copolypeptide vesicles, ${\rm R}_{m}^{{\rm H}} {\rm E}_{n} {\rm L}_{o} $ and ${\rm K}_{m}^{{\rm P}} {\rm R}_{n}^{{\rm H}} {\rm L}_{o} $ , is reported. Variation of the two distinct hydrophilic domains is used to tune cellular interactions without disrupting the self‐assembled structure. The aqueous self‐assemblies of these triblock copolypeptides in water are characterized using microscopy and DLS. Cell culture studies are used to evaluate cytotoxicity as well as intracellular uptake of the vesicles. The ability of polypeptides to incorporate ordered chain conformations that direct self‐assembly, combined with the facile preparation of functional, multiblock copolypeptide sequences of defined lengths, allow the design of vesicles attractive for development as drug carriers.

     

Structure of the polyion complex between poly(sodium P-styrene sulfonate) and poly(diallyl dimethyl ammonium chloride)

Stoichiometric and nonstoichiometric polyion complex films were prepared from poly(sodium p-styrene sulfonate) and poly(diallyl dimethyl ammonium chloride). X-ray photoelectron spectroscopy revealed that the ionic groups in the complex are more ionized than in each component polymer. Fluorescence measurements showed that the complex had a main emission peak around 300 nm, whereas the peak for its original polyanion occurred at 324 nm. With the monomer and excimer peaks of the phenyl rings taken to be at 294 and 324 nm, respectively, the ratio of excimer to monomer emission intensities increased in proportion to the mole fraction of polyanion in the observed range 0.44–0.59. There was no discontinuity at the stoichiometric composition. Furthermore, the change in peak position shows that the local aggregation of phenyl groups in the polyanion was destroyed by complexation with the polycation through Coulombic forces. These results, together with the visual observation of the transparency of the films, mean that the mixing between polyanion and polycation chains in the polyion complex is on the molecular level and that this polymer alloy is miscible.     

Uniform Rates of Decay in Anisotropic Thermo-Viscoelasticity

We consider the anisotropic and inhomogeneous thermo-viscoelastic equation. We prove that the first and second-order energy decay exponentially as time goes to infinity provided the relaxation function also decays exponentially to zero. While if the relaxation functions decay polynomially to zero, then the energy decays also polynomially. That is, the kernel of the convolution defines the rate of decay of the solution.