Tripodal oxazoline-based homochiral coordination cages with internal binding sites

Homochiral coordination cages, which have two well-defined internal binding sites for ammonium and organoammonium ions, have been constructed by Pd(II)-mediated self-assembly of preorganized tripodal oxazolines containing pyridine pendant groups.     

Layered double hydroxide as novel antibacterial drug delivery system

The cephalosporin class antibacterial agent, cefazolin, was intercalated into layered double hydroxides (LDHs) in order to improve the drug efficiency as well as to achieve the controlled release property. Cefazolin molecules were incorporated into LDH through conventional ion exchange reaction. X-ray diffraction pattern analyses confirmed that cefazolin molecules were intercalated between the interlayer spaces of LDH. Fourier-transform infrared spectra and high performance liquid chromatographs clearly showed that the drug molecules were stabilized in LDH lattice through electrostatic interaction and released without any changes in their chemical integrity. Antibacterial activity of the cefazolin-LDH nanohybrid was also examined by an in vitro test, such as the minimal inhibitory concentration (MIC) by dilution method. Consequently, the cefazolin-LDH nanohybrid revealed an enhanced antibacterial activity compared to the cefazolin itself not only due to an improvement of chemical stability of cefazolin molecules but also due to a controlled release property.     

Hollow Polydimethylsiloxane Beads with a Porous Structure for Cell Encapsulation

Based on a water‐in‐oil‐in‐water emulsion system, porous and hollow polydimethylsiloxane (PDMS) beads containing cells using a simple fluidic device with three flow channels are fabricated. Poly(ethylene glycol) (PEG) in the PDMS oil phase is served as a porogen for pore development. The feasibility of the porous PDMS beads prepared with different PEG concentrations (10, 20, and 30 wt%) for cell encapsulation in terms of pore size, protein diffusion, and cell proliferation inside the PDMS beads is evaluated. The PDMS beads prepared with PEG 30 wt% are exhibited a highly porous structure and facilitated fast diffusion of protein from the core domain to the outer phase, eventually leading to enhanced cell proliferation. The results clearly indicate that hollow PDMS beads with a porous structure could provide a favorable microenvironment for cell survival due to the large porous structure.

     

What types of investors generate the two-phase phenomenon?

We examine the two-phase phenomenon described by Plerou, Gopikrishnan, and Stanley (2003)  [1] in the KOSPI 200 options market, one of the most liquid options markets in the world. By analysing a unique intraday dataset that contains information about investor type for each trade and quote, we find that the two-phase phenomenon is generated primarily by domestic individual investors, who are generally considered to be uninformed and noisy traders. In contrast, our empirical results indicate that trades by foreign institutions, who are generally considered informed and sophisticated investors, do not exhibit two-phase behaviour.     

Nanoconfined heliconical structure of twist-bend nematic liquid crystal phase

We produced controlled heliconical structures of a twist-bend nematic (N_TB) liquid-crystal (LC) phase in nanoconfinement in a porous anodic aluminium oxide (AAO) film. The structural parameters of the N_TB phase such as conical angle and helical pitch can be modulated by varying the surface energy of the inner surface of the porous AAO film, done by using different self-assembled monolayers (SAMs). The LC molecules tend to be more freely packed, thus forming a larger conical angle, when placed on the tri-deca-fluoro-1,1,2,2-tetrahydrooctyl-trichlorosilane (FOTS)-treated substrate, which has a relatively low surface energy. In contrast, the molecules form a more tightly packed structure, and thus a smaller conical angle, when placed on the 2-(methoxy(polyethyleneoxy)-propyl)trimethoxysilane (PEG 6/9)-treated substrate, which has higher surface energy. This work improves our collective understanding of self-assembled heliconical structures in the N_TB phase.     

Combined system of optical coherence tomography and fluorescence spectroscopy based on double-cladding fiber

We report the development of an all-fiber multimodal system, based on a double-cladding fiber (DCF) and related devices, suitable for simultaneous measurements of optical coherence tomography (OCT) and fluorescence spectroscopy (FS). The DCF together with a DCF coupler and a single-body DCF lens has assisted in the realization of a multimodal but single-unit probe for the combined system. The DCF lens allowed simultaneous focusing of input beams for OCT and FS and also the effective collection of both signal beams from a sample. The DCF coupler could extract the OCT signal via the core channel and the FS signal through the cladding channel. The OCT image and the fluorescence spectra of a plant tissue were then simultaneously measured to validate the performance of the proposed multimodal system.     

Generation and detection of the radical cation and the dication derived from 4,9‐diethyl[1,4]dihydrodithiino[5,6‐f]benzotrithiole and its 5‐oxide

4,9‐Diethyl[1,4]dihydrodithiino[5,6‐f]benzotrithiole (DTBT) gave a radical cation, DTBT(•+), and a dication, DTBT(2+), on treatment with a single‐electron oxidizing reagent. Both compounds showed an ESR signal, whereas the dication, generated by this procedure, was silent for ¹H NMR. Hydrolysis of DTBT(2+) gave DTBT 1‐oxide (DTBT 1‐O) and 2‐oxide (DTBT 2‐O) together with DTBT and a mixture of several dioxides. A singlet‐state dication, DTBT(2+)‐S, which was generated upon treatment of DTBT 5‐oxide (DTBT 5‐O) with concentrated D₂SO₄, was detected by ¹H and ¹³C NMR. After 20 h, the NMR signals disappeared while the solution was active for ESR. The results suggest that (i) a species generated from DTBT by oxidation with the single‐electron oxidizing reagent is a triplet‐state dication, DTBT(2+)‐T, and (ii) DTBT(2+)‐S, initially generated, gradually isomerizes to DTBT(2+)‐T in the solution, and DTBT(2+)‐T forms a partial spin pair. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:394–401, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20445     

Exponential structural relaxation of a high purity silica glass

While most other glasses exhibit non-exponential structural relaxation characteristics even when the change of fictive temperature is small, a high purity silica glass exhibited exponential structural relaxation. This was demonstrated by showing that the non-exponential exponent or β value of the KWW function of the high purity silica glass approaches unity when the change of the fictive temperature approaches zero both from higher and lower temperature sides of the heat-treatment temperature. The non-exponentiality of the structural relaxation of this glass when fictive temperature change is finite is due to the change of relaxation time during the structural relaxation.     

Promoting grain growth in Ni-rich single-crystal cathodes for high-performance lithium-ion batteries through Ce doping

Journal of Solid State Electrochemistry - Preparing a high-performance Ni-rich single-crystal cathode for Li-ion batteries is challenging. This is because calcination must be performed at a high...