New concept bioceramics composed of octacalcium phosphate (OCP) and dicarboxylic acid-intercalated OCP via hydrothermal hot-pressing

Octacalcium phosphate (OCP) and adipic acid-intercalated complexed OCP (Adi-OCP) were synthesized. Moreover, we made ceramic bodies out of them through a hydrothermal hot-pressing (HHP) method. Characteristic features of both the powder and ceramics were investigated by the X-ray diffraction method (XRD). Surface morphology of the ceramics was observed by scanning electron microscopy (SEM). Density, compressive strength and pore size distribution of the ceramics were measured. Crystalline structure of the newly developed OCP ceramics had no phase transformation from the starting materials. Moreover, the newly developed OCP ceramics had good mechanical properties only through the HHP treatment with a temperature as low as 110 °C. In order to evaluate bioactivity, the ceramics were immersed in simulating body fluid (SBF). It was predicted that OCP and Adi-OCP had better bioactivity than that of conventional HAp ceramics.     

Spectroelectrochemical Investigations of the Spreading of 4-Pentadecyl Pyridine onto the Au(111) Electrode

The adsorption of 4-pentadecyl-pyridine (C15-4-Py) onto the Au(111) electrode was investigated with the help of electrochemical and spectroscopic techniques. Electrochemical studies demonstrated that a film of C15-4-Py spreads onto the metal surface at potentials close to the potential of zero charge (pzc) and desorbs from the electrode surface at potentials which are sufficiently negative. The character of C15–4-Py adsorption resembles adsorption of pyridine molecules at the Au(111) electrode, indicating that the film properties are to a large extent determined by the interaction between the pyridine moiety and the metal surface. Addition of 25 mol%) of 10-decyl-9-[2-(4-pyridyl)ethyl]anthracene(DPEA), a dye molecule, to the C15–4-Py film only slightly modified its properties but allowed the use of spectroscopic methods to study the film properties. Fluorescence spectroscopy and light scattering experiments were employed to study the potential-induced desorption and adsorption of the surfactant molecules. Using spectroelectrochemical techniques we have demonstrated that the desorption of the film and its readsorption involves the formation of micelles in the subsurface region and spreading of the micelles onto the electrode surface. A general mechanism of spreading of insoluble surfactants onto electrode surfaces has been proposed.     

Synthesis of polymer gel with chiral helical cavity by molecular imprinting using bifunctional vinyl monomers

The molecular imprinting method was applied for synthesizing gels with a chiral helical cavity using various bifunctional vinyl monomers, such as α-(benzyloxymethyl)acrylic acid derivatives as a monomer, and one-handed helical (+)-poly(diphenyl-2-pyridylmethyl methacrylate) as a template. The chiral gels were almost quantitatively prepared after removal of the template polymer by hydrolysis of the ester groups. The obtained gels exhibited chiral resolution powers toward various racemates, such as trans-stilbene oxide and Tröger's base, and the substituents on the phenyl group of the monomer significantly affected the recognition ability. The observed separation factors were higher than those of the gels prepared from the mono-functional vinyl monomer, methacrylic acid.     

Dual-color operation of a laser diode under current and temperature control

We describe a novel method that operates a laser diode with dual colors. Our system requires no external optical parts but does require current and temperature control. We can use either a single color on a time-sharing basis or dual colors simultaneously. The difference between the wavelengths is -0.6 nm, which is as much as 10 times that generated by current control alone. Temporal stability of the generated two wavelengths and the response time of the wavelength change were confirmed through a number of experiments.     

Silicone-containing polymer blend electrolyte membranes for fuel cell applications

Polymer electrolyte membranes are developed from blends of chemically durable silicone-containing epoxy (Si-Epoxy) and proton conducting sulfonic polyimide (SPI). A charge-transfer (CT) complex is formed between electron-donating dihydroxynaphthalene units in Si-Epoxy, and electron-accepting naphthalenediimide units in SPI, as confirmed via X-ray diffraction and visible spectroscopy. The blend membranes show comparable mechanical strength to Nafion 211, but the elongation to break is much lower, indicating better resistance to deformation under strain stress, attributed to CT complex formation. The chemical durability of the blend membranes was much higher than pure SPI according to Fenton's test, also attributed to CT complex formation. Meanwhile, the proton conductivity is dependent on the sulfonic acid content of the SPI, which in turn affects the fuel cell performance. The maximum proton conductivity was measured to be 23.1 mS cm⁻¹ at 80°C and 90 %RH for a 1:1 blend, and the membranes were successfully incorporated into PEFCs.     

Effective Thermal Conductivity of Rice Flour and Whole and Skim Milk Powder

ABSTRACT: The effective thermal conductivity for 3 kinds of powdered food (rice flour, whole milk powder, and skim milk powder) was measured at selected moisture contents, temperatures, and bulk densities. The transient heat probe method using twin probes was used for the determination of the effective thermal conductivity. The effects of moisture content, temperature, and bulk density on the effective thermal conductivity of samples were investigated. The observed values were compared with the values calculated from the thermal conductivity of air and powder, using the 3 kinds of structural model for thermal conductivity, that is, the series, parallel, and random heat transfer models. An improved random heat transfer model, in which a correction term was incorporated in the random heat transfer model, with the term written as a function of moisture content and temperature, was developed.     

Relationship between the gas transport properties and the refractive index in high‐free‐volume fluorine‐containing polyimide membranes

The refractive index and gas transport properties (i.e., permeability, diffusivity, and solubility) in the 2,2′‐bis(3,4‐dicarboxyphenyl) hexafluoropropane dianhydride (6FDA)‐based polyimides were systematically investigated in terms of their polymer fractional free volumes (FFVs). The permeability and diffusion coefficients of the 6FDA‐based polyimide membranes to hydrogen, oxygen, nitrogen, methane, and carbon dioxide were correlated with their FFVs, which were estimated with van Krevelen's group contribution method. Linear correlations were also observed between the gas transport properties and the refractive index of these polyimides. We described FFV as a function of the refractive index based on the Lorentz–Lorenz equation. Linear correlations were observed between their refractive‐index‐based FFVs and the gas permeability, diffusivity, and solubility coefficients of these 6FDA‐based polyimides membranes. However, the FFVs of the 6FDA‐based polyimides calculated from refractive index were 1.16–1.37 times larger than their FFV values. This FFV was dependent on the free‐volume space and optical factors, such as the refractive index and molar refraction, which affected the electronic structure and the interactions between the gas molecules and the polymer segments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

High-Resolution Stimulated Raman Gain Spectroscopy of Parahydrogen Crystals

High-resolution stimulated Raman gain spectroscopy of the Q₁(0) transition of para-H₂ crystals with varying ortho-H₂ concentrations is reported. A crystal containing 0.06% of ortho-H₂ showed a single sharp Raman transition with the width of less than 7 MHz. The Raman signal became broader with increasing concentration of ortho-H₂. At the concentration of 2%, the spectrum splits into a doublet. The components of the doublet have different dependence on the relative polarization of the pump and probe laser radiations. Physical origin of the splitting and the polarization dependence is yet to be understood.PACS numbers: 33.20 Fb, 42.65 Dr, 67.80 −s     

Suppression control of speed variation in an induction motor with fluctuating load by repetitive learning control

Induction motors are robust and inexpensive machines and are used widely for variable speed control because of the recent development of electronic technique. In the case where loads of the motors are compressors, pumps, and so on, the constant V/F control of the induction motors usually is employed because it is difficult to install speed sensors and accurate speed control is not required. In such loads, the rotational speed of the motors fluctuates considerably because the load torque is pulsated. When the frequency of the torque pulsation is close to the resonant frequency of the mechanical system, large vibration and acoustic noise are produced especially in the low-frequency region. This paper proposes a method to suppress the variation of the rotational speed of the V/F controlled induction motor with a fluctuated load by feedforward compensation using a timing sensor of 1 pulse/rev, considering that the load torque varies periodically. The feedforward data by a period for the compensation is obtained by the learning control based on the repetitive control in which the motor speed is controlled by periodically reflecting the past speed error on the present V/F input to the inverter. Effectiveness of the proposed method is confirmed by approximate analysis, simulations and experiments.