Design and fabrication of a superhydrophobic glass surface with micro-network of nanopillars

The wetting property of a superhydrophobic glass surface with a micro-network of nanopillars fabricated from colloidal lithography and plasma etching is investigated in this paper. The micro-network distribution of nanospheres can be modulated by diluting the nanosphere concentration and controlling the spin rate. The micro-network of nanospheres spun on the glass surface serves as a mask for nanopillars during the plasma etching process. After the fabrication, the nano-structured surface is treated with fluoroalkylsilane self-assembled monolayers to obtain superhydrophobicity. Among several spin rates, the minimum colloidal network area density from a 100 nm polystyrene nanosphere solution diluted to 0.026% was found at a spin rate of 4000 rpm. The sample with the lowest network area density shows a good quality of superhydrophobicity, having the highest water contact angle and the lowest sliding angle among samples with other network area densities. In particular, samples with a micro-network of pillars also showed mechanical robustness against finger rubbing. To assess the superhydrophobic behavior in-depth, a size-dependent contact angle equation is proposed for use with a high contact angle (>135°) and with a Bo (Bond number) ? 1. Furmidge's sliding angle equation is also modified; it is derived considering a static contact angle to simplify the prediction of the sliding angle. The contact and sliding angle measurements from samples with a micro-network of nanopillars show good agreement with the proposed equations.     

Calix[4]bis(thiacrown): assembly of an endocyclic disilver(I) complex and exocyclic 3D copper(I) coordination polymers

Calix[4]bis(thiacrown-5) (L) with 1,3-alternating conformation was employed as a strong dinucleating ligand for the soft metal ions AgI and CuI. The reaction of L with AgPF6 afforded a discrete endo-coordinated disilver(I) complex 1, [Ag2L](PF6)2. In contrast, mixed products (2a + 2b) consisting of 3D networks were obtained from the reaction of L and CuI; 2b linked with a Cu4I4 cubane unit was shown to generate photoluminescence, while 2a linked with a Cu2I2 rhomboid unit does not.     

A rapid and sensitive liquid chromatography/positive ion tandem mass spectrometry method for the determination of cimetropium in human plasma by liquid-liquid extraction

We have developed and validated a simple detection system with high-performance liquid chromatography (HPLC) with positive ion electrospray ionization tandem mass spectrometry (ESI-MS/MS) for determining cimetropium levels in human plasma using scopolamine butyl bromide as an internal standard (I.S.). The acquisition was performed in the multiple reaction monitoring (MRM) mode, by monitoring the transitions: m/z 357.9 > 103.1 for cimetropium and m/z 359.9 > 103.1 for butyl-scopolamine. The method involves a simple single-step liquid-liquid extraction with dichloromethane. The analyte was chromatographed on an YMC C18 reversed-phase chromatographic column by isocratic elution with 10 mM ammonium formate buffer-methanol (19:81, v/v; adjusted to pH 4.0 with formic acid). The results were linear over the studied range (0.2-100 ng ml(-1)), with r2 = 1.0000, and the total analysis time for each run was 2 min. Intra- and interassay precisions were 0.70-8.54% and 1.08-4.85%, respectively, and intra- and interassay accuracies were 97.56-108.23% and 97.48-103.91%, respectively. The lower limit of quantification (LLOQ) was 0.2 ng ml(-1). At this concentration, mean intra- and interassay precisions were 8.54% and 4.85%, respectively, and mean intra- and interassay accuracies were 97.56% and 98.91%, respectively. The mean recovery ranged from 62.71 +/- 4.06 to 64.23 +/- 2.32%. Cimetropium was found to be stable in plasma samples under typical storage and processing conditions. The devised assay was successfully applied to a pharmacokinetic study of cimetropium bromide administered as a single oral dose (150 mg) to healthy volunteers.     

Defect-free polymer multilayers prepared via chemoselective immobilization

In this paper, we investigated electrochemical properties of polymer multilayers on gold substrates using impedance spectroscopy. The multilayer was prepared by chemoselective ligation between aldehyde- and oxyamine-functionalized polymers via a layer-by-layer approach. The impedance spectra in a buffer solution in the absence of redox species revealed the formation of highly impermeable and defect-free films. The dielectric thickness of the polymer film, which is proportional to the reciprocal of capacitance, linearly increased as the number of deposition layer increased. The defect area of the polymer multilayer was obtained using the faradaic impedance with redox species. The surface coverage of eight polymer layers was determined to be 99.99%. Thus, the layer-by-layer deposition via chemoselective ligation offers a new way to prepare a highly insulating and defect-free polymer layer with finely tunable capacitance as a function of the number of deposition layers.     

Enhanced electrical percolation due to interconnection of three-dimensional pentacene islands in thin films on low surface energy polyimide gate dielectrics

The role of lateral interconnections between three-dimensional pentacene islands on low surface energy polyimide gate dielectrics was investigated by the measurement of the surface coverage dependence of the charge mobility and the use of conducting-probe atomic force microscopy (CP-AFM). From the correlation between the electrical characteristics and the morphological evolution of the three-dimensionally grown pentacene films-based field-effect transistors, we found that during film growth, the formation of interconnections between the three-dimensional pentacene islands that are isolated at the early stage contributes significantly to the enhancement process of charge mobility. The CP-AFM current mapping images of the pentacene films also indicate that the lateral interconnections play an important role in the formation of good electrical percolation pathways between the three-dimensional pentacene islands.     

One-pot synthetic route to polymer-silica assembled capsule encased with nonionic drug molecule

A novel combinational drug delivery system, in which drug molecules could be dually encapsulated by soft (polymer) and hard (inorganic) vehicles has been successfully prepared via a simple one-pot synthesis; its improved chemotherapeutic efficacy has been verified through in vitro experiments.     

Characterization and epitope mapping of two monoclonal antibodies against human CD99

CD99 plays a critical role in the diapedesis of monocytes, T cell differentiation, and the transport of MHC molecules. Engagement of CD99 by agonistic monoclonal antibodies has been reported to trigger multifactorial events including T cell activation as well as cell-cell adhesion during hematopoietic cell differentiation. In this study, to identify the functional domains participating in the cellular events, we mapped the epitopes of CD99, which are recognized by two agonistic CD99 monoclonal antibodies, DN16 and YG32. Using recombinant fusion proteins of GST with whole or parts of CD99, we found that both antibodies interact with CD99 molecules independently of sugar moieties. DN16 mAb detected a linear epitope located in the amino terminal region of CD99 while YG32 mAb bound another linear epitope in the center of the extracellular domain. To confirm that the identified epitopes of CD99 are actually recognized by the two mAbs, we showed the presence of physical interaction between the mAbs and the fusion proteins or synthetic peptides containing the corresponding epitopes using surface plasmon resonance analyses. The dissociation constants of DN16 and YG32 mAbs for the antigen were calculated as 1.27 x 10(-7) and 7.08 x 10(-9) M, respectively. These studies will help understand the functional domains and the subsequent signaling mechanism of CD99.     

Photoluminescence of Cd1-xMnxS (x < or = 0.3) nanowires

Cd1-xMnxS (x = 0.1-0.3) nanowires were synthesized by using the chemical vapor deposition method. They all consist of a single-crystalline wurtzite CdS structure with a [010] or [011] growth direction. The X-ray diffraction pattern reveals the contraction of the lattice constants due to the incorporation of Mn. The Mn2+ emission at approximately 2.15 eV, originating from the d-d (4T1 --> 6A1) transition, appears below 50-80 K. Its decay time is in the range of 0.55-1 ms, showing a decrease with increasing Mn content. The Mn doping reduces significantly the decay time of band-edge emission from 590 ps to 20-30 ps. Upon applying magnetic field (up to 7 T), the Mn2+ emission is suppressed and donor-acceptor pair emission becomes dominant, suggesting the energy transfer from the band electrons to the Mn2+ ions.     

Imidazole-based excited-state intramolecular proton-transfer materials: synthesis and amplified spontaneous emission from a large single crystal

We have synthesized a novel class of imidazole-based excited-state intramolecular proton-transfer (ESIPT) materials, i.e., hydroxy-substituted tetraphenylimidazole (HPI) and its derivative HPI-Ac, which formed large single crystals exhibiting intense blue fluorescence and amplified spontaneous emission (ASE). Transparent, clear, and well-defined fluorescent single crystals of HPI-Ac as large as 20 mm x 25 mm x 5 mm were easily grown from its dilute solution. From the X-ray crystallographic analysis and semiempirical molecular orbital calculation, it was deduced that the four phenyl groups substituted into the imidazole ring of HPI and HPI-Ac allowed the crystals free from concentration quenching of fluorescence by limiting the excessive tight-stacking responsible for intermolecular vibrational coupling and relevant nonradiative relaxation. Fluorescence spectral narrowing and efficient ASE were observed in the HPI-Ac single crystal even at low excitation levels attributed to the intrinsic four-level ESIPT photocycle.