Evidence and mechanisms of filling polymerization by plasma-induced graft polymerization

Using a plasma-induced graft polymerization technique, which is well known as a surface modification method, the grafted polymer was formed in pores of the porous material. This study examined the filling mechanism. Five thin porous films were sandwiched together, and employed as the substrate. The substrate was treated by plasma, and the change in surface tension and radical formation was measured for each sheet after the sheet was separated. The only surface on which surface-tension change was detected, was that of the sheet directly exposed to the plasma. Although plasma treatment made polymer radicals primarily on the outer surface of the sheet, the treatment also formed a few radicals inside the sheets. The radicals inside the sheets reacted with methylacrylate and grafted polymer formed in the pores. The location of grafted polymer depended on the balance between monomer diffusivity and reactivity. The grafting rate depended on which monomer solvent was used for the polymerization. Thus, the grafted membrane morphology could be controlled by varying the grating solvent composition. © 1996 John Wiley & Sons, Inc.     

Integrating over quiver variety and BPS/CFT correspondence

Letters in Mathematical Physics - We show the vertex operator formalism for the quiver gauge theory partition function and the qq-character of the highest weight module on quiver, both associated...     

Determination of ammonium in river water and sewage samples by capillary zone electrophoresis with direct UV detection

We developed capillary zone electrophoresis (CZE) with direct UV detection for determination of ammonium in environmental water samples. Ammonium in the samples was partly converted into ammonia in the alkaline background electrolyte (BGE) during migration and was detected by molecular absorption of ammonia at 190 nm in approximately 7 min. The limit of detection (LOD) for ammonium was 0.24 mg/l (as nitrogen) at a signal-to-noise ratio of three. The respective values of the relative standard deviation (RSD) of peak area, peak height, and migration time for ammonium were 2.1, 1.8, and 0.46%. Major alkali and alkaline earth metal ions coexisting in the samples did not interfere with ammonium determination by the proposed method. The proposed method determined ammonium in surface water and sewage samples. The results were compared to those obtained using ion chromatography (IC).     

Inclusion Complex Formation of Thiacalix[4]arene and Xe in Aqueous Solution Studied by Hyperpolarized 129Xe NMR

The inclusion complex formation of 4-sulfothiacalix[4]arene sodium salt (STCAS) and Xe has been investigated by using hyperpolarized ¹²⁹Xe NMR spectroscopy. Our new continuous-flow type hyperpolarizing system has advantageous capabilities that can supply hyperpolarized gases continuously and directly to a sample solution in a NMR tube. Consequently saturated Xe concentration in the aqueous solution of STCAS is maintained during the NMR experiment, and ¹²⁹Xe NMR spectra can be obtained in remarkably short time. STCAS concentration dependence of ¹²⁹Xe chemical shift has been analyzed in an elaborated way by a computer method as well as a simple graphic method that we have proposed. The association constant K:13.6±0.8 M⁻¹ at 25 °C was obtained, and further analysis of the temperature dependence has successfully given thermodynamic parameters of enthalpy (ΔH) and entropy (ΔS) for the inclusion complex formation: ΔH = −11.9±1.9 kJ mol⁻¹ and ΔS = −17.4±5.8 JK⁻¹ mol⁻¹. The energetic aspects of complex formation are discussed from the size effect and from the molecular theory of standard entropy, and a release of definite number of water molecules from STCAS cavity is suggested in the inclusion complex formation with Xe.     

Non-Darcian effects on conjugate natural convection between horizontal concentric cylinders filled with a porous medium

An analysis is presented of steady conjugate free convection between two horizontal concentric cylinders filled with a fluid-saturated porous medium; the innermost cylinder surface is maintained at a high temperature and the outermost cylinder surface at a lower one. The velocity-pressure-gradient relation is taken to be nonlinear, with departure from the linear Darcy situation measured by a parameter F₀. The investigation is based on the numerical solution, by a finite-difference method, of the full momentum and energy equations. The streamline and isotherm patterns as well as the local and mean Nusselt numbers are plotted for several physical parameters to show some of the flow and heat transfer characteristics. It is found that all parameters play an important role in the flow and heat transfer characteristics. The model can be applied to a variety of engineering problems.     

Characterization of Si-added aluminum oxide (AlSiO) films for power devices

Synthesis of Si-added aluminum oxide (AlSiO) films is attempted as an insulating film with both a wide bandgap and a high dielectric constant. Electrical characteristics of AlSiO films are investigated. Leakage current of the AlO film is suppressed by Si addition and is minimized with Si composition ratio of 12%. Capacitance versus voltage (C-V) measurements are carried out for Au/AlSiO/Si MIS structure. Both flat band shift and hysteresis of the C-V characteristics are suppressed by Si addition. A low leakage current is demonstrated for Au/AlSiO/n-SiC MIS structure.     

Novel family of low molecular weight hydrogelators based on L-lysine derivatives

New L-lysine derivatives with a positively charged terminal can gel water below 1 wt%; particularly, 1a and 2a form a hydrogel at 0.3 wt% corresponding to approximately 12,300 and 12,500 waters/gelator molecule, respectively.